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AS04 - Atmospheric Chemistry in Highly Polluted Environments: Emissions, Fate, and Impacts
Thursday, June 07, 2018 | 325B | 11:00-12:30
AS04-D4-AM2-325B-001 (AS04-A017)
Top-Down Estimate of Black Carbon Emissions for City Cluster Using Ground Observations: A Case Study in Southern Jiangsu, China
Yu ZHAO1#+, Xuefen ZHAO1, Dong CHEN1, Jie ZHANG2
1 Nanjing University, China, 2 Jiangsu Provincial Academy of Environmental Science, China
#Corresponding author: +Presenter

We combined chemistry transport model (CTM), multiple regression model and available ground observation, to derive top-down estimate of black carbon (BC) emissions and to reduce deviations between simulations and observations for southern Jiangsu city cluster, a typical developed and polluted region in eastern China. Scaled from a high-resolution emission inventory for 2012 based on changes in activity levels, BC emissions in southern Jiangsu were calculated at 27.0 Gg /yr for 2015 (JS-prior). The annual mean concentration of BC at Xianlin Campus of Nanjing University (NJU, a suburban site) was simulated at 3.4 μg/m3, 11% lower than the observed 3.8 μg/m3. It was 3.9 μg/m3 at Jiangsu Provincial Academy of Environmental Science (PAES, an urban site), 56% higher than the observed 2.5 μg/m3. Constrained with the top-down method, BC emissions were 13.4 Gg/yr (JS-posterior), 50% smaller than JS-prior, and stronger seasonal variation were found. Biases between simulations and observations were reduced for most months at two sites when JS-posterior was applied. In particular, at PAES, the simulated annual mean was elevated to 3.1 μg/m3 and the annual normalized mean error (NME) decreased by 24.8%. The effects of numbers and spatial representativeness of observation sites on top-down estimation were further quantified. Best CTM performance was obtained when observation of both sites were used, with their difference in spatial functions considered. Given the limited BC concentration data in the area, therefore, more measurements with better spatiotemporal coverage were recommended for constraining BC emissions effectively. Moreover, top-down estimates derived from JS-prior and the Multi-resolution Emission Inventory for China (MEIC) were compared to test the sensitivity of the method to initial emission input. The differences in emission levels, spatial distributions and CTM performances were largely reduced after constraining, implying that the impacts of initial inventories were limited on top-down estimate.

AS04-D4-AM2-325B-002 (AS04-A060)
Air Quality Impact of Shipping Emissions and Deca Design in China
Huan LIU#+, Zhaofeng LV
Tsinghua University, China
#Corresponding author: +Presenter

With the fast development of seaborne trade and relatively more efforts to reduce other sources in China, shipping emissions contribute more and more significantly to air pollution. In this study, the air quality model CMAQ (Community Multiscale Air Quality) was applied to quantify the impact of shipping emissions within 200 nautical miles (Nm) of the Chinese coast on the annual and seasonal concentrations of PM2.5 and ozone for the base year 2015 in China. The results showed that shipping emissions increase the annual PM2.5 and ozone concentrations in eastern China were 0.5~7 μg/m3 and -2~8 μg/m3 respectively, and its annual contribution rates to PM2.5 were 0.3%~8.2% at core coastal cities, among which greater influence in YRD (Yangtze River Delta) and PRD (Pearl River Delta). The MD (Maximum Distance between coastline and areas impacted by ship emissions on PM2.5 concentration which is larger than a specific threshold) of △Cannual,PM2.5>0.1 μg/m3, △Cannual,PM2.5>0.5 μg/m3 and △Cannual,PM2.5>1 μg/m3, was 955.9 km, 512.7 km and 347.4 km. In addition, since the sea breeze can carry ship pollutants to inland areas, the average frequency of △Cdaily,PM2.5 >5 μg/m3 on coastal cities in conditions of sea breeze reached 80%. In winter, the emissions from shipping sector decrease the PM2.5 and ozone concentrations in BTH (Beijing-Tianjin-Hebei), probably due to wind directions, NH3-rich conditions and VOCs-limited regime. To identify an efficient DECA (Domestic Emission Control Area) spatial scope, we used a tracer-based technique in a source-oriented CMAQ to determine the shipping emissions from different specific areas on PM2.5 concentrations in coastal cities. The results suggested that the DECA should be designed within Bohai Rim, 12nm in PRD from the coast, 50nm in YRD from the coast, which was enough to control the influence of shipping emissions on PM2.5 in inland areas in China.

AS04-D4-AM2-325B-003 (AS04-A020)
Impacts of Injection Height of Industrial Emissions on Recent SO2 Trend over China
Yang YANG1#+, Hailong WANG2, Steven SMITH2, Philip RASCH2
1 Nanjing University of Information Science and Technology, China, 2 Pacific Northwest National Laboratory, United States
#Corresponding author: +Presenter

China has suffered from severe haze in recent years, which is a major public health concern. Sulfur dioxide (SO2) emitted from power plants and industrial facilities forms sulfate aerosols, a major contributor to aerosol pollution in China. Accurate SO2 emissions trends from China are important for air quality prediction and pollution mitigation, as well as the assessment of climate forcing. Based on satellite observations, a recent study (Li et al., 2017) reported a 75% reduction of SO2 emissions in China during the past decade, a deeper reduction than seen in bottom-up inventories. We examine here a potential reason for this discrepancy. While inventories agree that power plant emissions have decreased, emissions from other industrial sectors have not decreased nearly as much. The more dispersed emissions from the industrial sector are less likely to be injected into the atmosphere at high elevations. While this may render these emissions less visible in satellite retrievals, the injection height of these emissions is not known. In this study, using the sulfur tagging capability implemented in an aerosol-climate model, we quantify the trend of SO2 and sulfate over China over the 21st century to date from a bottom-up perspective and examine the impact of uncertainties in injection height trend and vertical profiles. The model results will be compared with satellite retrievals to identify and attempt to resolve major discrepancies.

AS04-D4-AM2-325B-004 (AS04-A041)
An Inventory of Air Pollutions from Road Transport in Thailand: Status and Trend During the Past Decade
National Institute for Environmental Studies, Japan
#Corresponding author: +Presenter

Energy consumption, a major anthropogenic source of GHG emissions and pollutants contribute to climate change problem. Transport activity, a main economic development driver, is the largest fuel consumer in Thailand. This study attends to investigate the air pollution situation from road transport activity in Thailand. An inventory of 6 vehicle exhaust emissions, including ozone precursors (NOx, CO), particulate matter (PM10), and greenhouse gases (CO2, CH4, N2O) during the year 2000 to 2016 is developed based on the actual activity data, input parameter to GAINS model. The study found through the past two-decade road transport activity contributes average annual emissions about 492.8 Tg NOx, 992.1 Tg CO, 37.5 Tg PM10, 55,265 Tg CO2, 2.2 Tg N2O, and 29.5 Tg CH4 and with the uncertainty in the emission estimation based on probability density function as ±57.2% for NOx, ±51.9% for CO, ±31.5% for PM10, ±14.2% for CO2, ±15.9% for CH4, and ±16.6% for N2O. According to the trend of emissions found NOx, CO2, and CH4, has an upward trend at average annual rate 1%, 6%, and 2% respectively, inversely for CO and PM10 at the reduction rate 3% and 2% respectively, whereas fluctuate in narrow range for N2O emission. According to this inventory identifies that NOx, PM10, and CO2, mainly emitted from heavy duty vehicle with diesel-fueled, N2O and CO largely come from light duty car with gasoline-fueled, CH4 major contributed from heavy duty vehicle with compress natural gas (CNG) – fueled which overwhelmed from light duty car with gasoline-fuel and motorcycle.

AS04-D4-AM2-325B-005 (AS04-A049)
Changes in Ammonia Agricultural Emissions and Their Impact on Surface PM2.5 Pollution in China During 2005-2015
Youfan CHEN#+, Lin ZHANG, Yuanhong ZHAO
Peking University, China
#Corresponding author: +Presenter

Increasing human activities have led to more and more ammonia (NH3) emitted into atmosphere, causing negative consequences on natural ecosystems and global environment. Due to its intensive agriculture activities, China is one of the largest NH3 emitting countries contributing about 57% of the global NH3 emissions. Recent AIRS satellite observations suggested that NH3 concentrations over China are increasing at a rate of 0.08 ppbv (2.3%) a-1. Here we will present our bottom-up Chinese NH3 agricultural emissions over 2005-2015 at 1/2°x 2/3°horizontal resolution and use the GEOS-Chem chemical transport model to simulate their impact on surface PM2.5 pollution. Our estimates of NH3 agricultural emissions include detailed information on 18 main crops’ fertilizer application practices and accounts for meteorological modulation of NH3 emission factors over China. We find that total emission of NH3 in China increased from 12.1 Tg NH3 a-1 in 2005 to 13.3 Tg NH3 a-1 in 2012, and then remained stable during 2013-2015 with emissions of 13.1 Tg NH3 a-1. Although nitrogen fertilizer application kept growing in the past 10 years in China, the fertilizer-induced NH3 emissions were almost unchanged because of replacement of Ammonium Bicarbonate by Urea and compound fertilizer. We find that NH3 emissions alone cannot explain the satellite observed increasing trends in the NH3 concentration over China. We will also discuss how the NH3 agricultural emission changes, combined with changes in SO2 and NOx emissions over 2005-2015 affect the surface PM2.5 concentration over China.

AS04 - Atmospheric Chemistry in Highly Polluted Environments: Emissions, Fate, and Impacts
Thursday, June 07, 2018 | 325B | 13:30-15:30
AS04-D4-PM1-325B-006 (AS04-A010)
Unique Air Chemistry over the Dead Sea
Menachem LURIA#+
The Hebrew University of Jerusalem, Israel
#Corresponding author: +Presenter

The Dead Sea in Israel is the deepest site in the world. Its shoreline is more than 400 meters below sea level, the length of the water body is about 100 km (south to north) and its width is nearly 10 km. Mountain ridges that are nearly 1 km above the water, limit the air flow from east to west and vice versa and the only ventilation is along the narrow north-south axis. The salinity of Dead Sea water is ten times greater than that of ocean water, and the content of bromine is much higher than that found in the oceans.

The discovery of ozone depletion over the sea during the 1990’s was a great puzzle. It decreased from background levels to a few ppb. The common mechanism for ozone decrease is titration with freshly emitted nitrogen oxide. However, NOx levels at that location were extremely low. A follow up study revealed that the levels of bromine oxide (BrO) were higher than any levels previously reported. While BrO was known to catalytically cause ozone depletion over Antarctica, the environment at the Dead Sea is quite different, with temperature often above 40oC during the summer. A mechanism is proposed to explain this occurrence.

Another unique phenomenon relates to the mercury chemistry over the Sea. The atmospheric concentration of elemental mercury (EM) over non-polluted areas is relatively constant at ~2ng/m3 with very little diurnal and/or seasonal changes. Over the Dead Sea it was found that EM shows significant diurnal changes. During the daytime its level decreases to below 1 ng/m3 and at night it increases to above 3 ng/m3. The decrease in EM correlates with a parallel elevation of reactive gaseous mercury (RGM), as well as an increase in the concentration of BrO.

AS04-D4-PM1-325B-007 (AS04-A047)
Fundamental Importance of Nitrogen Isotopic Fractionation During Particulate Nitrate Formation: Theoretical Calculation, Field Validation and Application in Apportioning NOx Sources
Yanlin ZHANG#+
Nanjing University of Information Science, China
#Corresponding author: +Presenter

Current application of stable isotopes in atmospheric particulate nitrate (pNO3-) to partition NOx (=NO+NO2) source contributions generally presupposes that nitrogen isotopic fractionation during the conversion of NOx to NO3- is minor. Here we report that the δ15N and δ18O values  of fresh pNO3- in fine particles (PM2.5) collected through biomass burning experiment are  and , respectively, with δ15N-pNO3- values much higher than the isotopic source signature of NOx from biomass burning (1.04±4.13‰). The large difference between δ15N-NOx and δ15N-pNO3- can be perfectly explained by the N isotopic fractionation values (ԑN) due to the gas-particle conversion, which were quantified through a newly-developed computational quantum chemistry (CQC) module. As an application of isotope-based source apportionment, δ15N-pNO3- values (10.93±3.32‰, n=43) of ambient pNO3- were determined at an urban site with intense traffic in Eastern China. Our results show that almost all NOx derived from coal combustion without the consideration of isotopic fractionation. After incorporating the CQC-calculated ԑN values  into a Bayesian isotope mixing model, results reveal that the contribution proportions of coal combustion and road traffic to urban NOx are 32±11% and 68±11%, respectively, which agree well with a regional bottom-up emission inventory of NOx. Moreover, the variation pattern of OH contribution toambient pNO3- formation calculated by the CQC module is also consistent with that simulated by WRF-Chem. A reanalysis of reported δ15N-pNO3- data in China suggests that NOx emissions from coal combustion were substantively overestimated (>54±31% on average) nationwide without the consideration of isotopic fractionation.

AS04-D4-PM1-325B-008 (AS04-A070)
Change in Submicron Particle Composition and Characteristics due to Large Amount of Firecrackers Burning
Neeraj RASTOGI#+, Atinderpal SINGH, Rangu SATISH
Physical Research Laboratory, India
#Corresponding author: +Presenter

High concentrations of air pollutants have profound impacts on air quality and human health, as well as on climate through directly and indirectly affecting Earth’s radiation budget and hydrological cycle. Highly polluted environment can be result of several long-term and/or short term emission sources, atmospheric processes, and meteorological conditions over a given region. This study presents changes in concentrations, composition and characteristics of non-refractory particulate matter smaller than 1 µm in aerodynamic diameter (NR-PM1), and black carbon (BC) during Diwali festival (October 19th, 2017). Diwali is the biggest festival of India where people do lighting everywhere using earthen lamps and candles, and burn huge amount of firecrackers, which are short-term big source of fine particles and their precursors. Online measurements (1 min integration time) of organics, SO42-, NO3-, NH4+, Cl- were performed using high-resolution time of flight aerosol mass spectrometer (HR-ToF-AMS) and that of BC with seven wavelength aethalometer over a big urban city (Ahmedabad). Sharp increase (8 to 10 times higher) in concentrations of all the measured species was observed on the evening of Diwali that persisted overnight likely due to formation of secondary inorganic aerosol. Aerosol neutralization ratio (ANR, defined as the molar ratio of NH4+ to sum of SO42-, NO3- and Cl-), an indicative of aerosol acidity, reduced to as low as 0.1 on Diwali night, which has several implications. Such acidic aerosol can affect the properties of various chemical species e.g., solubility of metals emitting from firecrackers, formation of secondary particles etc. Further, variations in H:C and O:C ratios before, during and after Diwali suggests fresh emissions of primary organics during Diwali night, and highly oxidized secondary organic formation on next day. BC370/BC880 ratios during Diwali suggest that emissions from biomass burning type sources were contributing more than that from fossil fuel burning to carbonaceous aerosol.

AS04-D4-PM1-325B-009 (AS04-A076)
Fate of Pollution Emitted During the 2015 Indonesian Fire Season
Mijeong PARK#+, Helen WORDEN, Louisa EMMONS, Simone TILMES, Benjamin GAUBERT
National Center for Atmospheric Research, United States
#Corresponding author: +Presenter

The El Niño-driven fire season in Indonesia, 2015, is recorded to have the most severe fire emissions since NASA’s Earth Observation System (EOS) satellites started making observations of tropospheric pollutants from space. Carbon monoxide (CO), one of the major pollutants emitted during the fire season, has direct impacts on chemistry in the troposphere as a precursor to ozone O3 and carbon dioxide (CO2) and through interactions with the hydroxyl radical (OH) that increase the lifetime of methane (CH4). The relatively long chemical lifetime of CO (weeks to months) enables long-range transport as well as vertical transport into the upper troposphere and lower stratosphere (UTLS) region. In this study, measurements of CO from the Terra/MOPITT (Measurement of Pollution in the Troposphere) and Aura/MLS (Microwave Limb Sounder) are used to characterize the global impact of high CO emitted during the 2015 Indonesian fire season. The MOPITT and MLS instruments together provide a powerful tool for exploring global distributions of CO with overlap in the UTLS region. Simulations of CO from the Community Atmosphere Model with Chemistry (CAM-chem) are used to better understand transport pathways of CO from the surface into the lower stratosphere. We find that high concentrations of CO from the September-October 2015 Indonesian fires persisted in the UTLS throughout 2016, much longer than previous years with significant fire emissions.

AS04-D4-PM1-325B-010 (AS04-A008)
Long-Term Influence of Aerosols on Tropospheric NO2 Retrieval over China Based on OMI and TropOMI Sensors
Mengyao LIU1+, Jintai LIN1#, K. Folkert BOERSMA2, Gaia PINARDI3, Yang WANG4, Julien CHIMOT5, Thomas WAGNER4, Pinhua XIE6, Henk ESKES7, Van Roozendael MICHEL3, Francois HENDRICK3
1 Peking University, China, 2 Royal Netherlands Meteorological Institute, Netherlands, 3 Royal Belgian Institute for Space Aeronomy, Belgium, 4 Max Planck Institute for Chemistry, Germany, 5 Delft University of Technology, Netherlands, 6 Chinese Academy of Sciences, China, 7 Royal Dutch Meteorological Institute, Netherlands
#Corresponding author: +Presenter

Satellite-retrieved vertical column densities (VCD) of tropospheric nitrogen dioxide (NO2) are important for emission estimate, trend analysis and air quality evaluation. Aerosols have a strong influence on satellite NO2 retrieval, especially over China and many other regions with high aerosol loadings. However, most current-generation retrieval productsdo not explicitly account for aerosol optical effects that vary greatly with space and time. Here we present an improved retrieval of NO2 VCD over China, Peking University OMI NO2 Product (POMINO v1.1), that explicitly accounts for aerosol influences. In POMINO v1.1, the daily aerosol information for NO2 retrieval is based on GEOS-Chem simulations constrained by MODIS/Aqua monthly AOD and CALIOP/CALIPSO monthly climatological aerosol extinction profiles. Comparisons with ground-based MAX-DOAS NO2 measurements indicated that the explicit aerosol treatment in POMINO v1.1 greatly improves the day-to-day variation of NO2 VCD, with a small bias, especially on polluted (hazy) days. We further apply our algorithm to the newly launched TropOMI to study the influence of aerosols on higher-resolution retrieval of tropospheric NO2 VCD over China.

Based on POMINO v1.1, we evaluate for the first time the impact of aerosols on retrieved NO2 trends and interannual variability since 2005, a critical use of satellite data for environmental assessment. We examine the aerosol influences over different regions of China, considering their different economic development patterns, aerosol characteristics, atmospheric states and surface features. Overall, we find significant aerosol influences at various spatial scales.

AS04 - Atmospheric Chemistry in Highly Polluted Environments: Emissions, Fate, and Impacts
Thursday, June 07, 2018 | 325B | 16:00-18:00
AS04-D4-PM2-325B-011 (AS04-A062)
Enhanced Effectiveness of NOx Control from Simultaneous Reductions of VOC and NH3 for Reducing Air Pollution in Beijing-Tianjin-Hebei Region, China
Jia XING#+, Dian DING
Tsinghua University, China
#Corresponding author: +Presenter

As one common precursor for both PM2.5 and O3 pollution, NOx gains great attention because its controls can be beneficial for reducing both PM2.5 and O3. However, the effectiveness of NOx controls for reducing PM2.5 and O3 are largely influenced by the ambient levels of NH3 and VOC, exhibiting strong nonlinearities characterized as NH3-limited/-poor and NOx-/VOC-limited conditions, respectively. Quantification of such nonlinearities is prerequisite to making suitable policy decisions but limitations of existing methods were recognized. In this study, a new method was developed by fitting multiple simulations of a chemical transport model with a set of polynomial functions (denoted as pf-RSM) to quantify responses of ambient PM2.5 and O3 concentrations to changes in precursor emissions. An advantage of the pf-RSM method is that the nonlinearity in PM2.5 and O3 responses to precursor emission changes can be characterized by quantitative indicators, including (1) peak ratio (denoted as PR) representing VOC-limited or NOx-limited condition, (2) suggested reduction ratio of VOC to NOx (denoted as VNr) to avoid increasing O3 under VOC-limited condition, (3) flex ratio (denoted as FR) representing NH3-poor or NH3-rich condition, and (4) enhanced benefits in PM2.5 reductions from simultaneous reduction of NH3 with the same reduction rate of NOx. A case study in Beijing-Tianjin-Hebei region suggested that at urban area the NOx emission reduction rate need be greater than 20 %–60 % to pass the transition from VOC-limited to NOx-limited. A simultaneous VOC control can avoid increasing O3 during the transition. Enhanced benefits in PM2.5 reductions from simultaneous reduction of NH3 were estimated to be 0.04–0.15 µg m-3 PM2.5 per 1 % reduction of NH3 along with NOx. Thus, simultaneously reducing NH3 and VOC emission along with NOx reduction is recommended to assure the control effectiveness of PM2.5 and O3.

AS04-D4-PM2-325B-012 (AS04-A001)
Re-Examine the APEC Blue in Beijing 2014
Ting WANG#+, Pucai WANG
Chinese Academy of Sciences, China
#Corresponding author: +Presenter

APEC blue was coined to describe the impact of short-term curbs on air pollution during the Asian-Pacific Economic Cooperation (APEC) Summit organized in Beijing in November 2014 and has been a hot topic among both general public and scientific sector in China. The consensus that gaseous agents NO2 and SO2 are greatly reduced in response to the control and restriction strategies implemented during the Summit period is shared by earlier literature. However, the re-examination of APEC blue conducted in the present study comes to a more contrasted conclusion. The remarkable drop in NO2 abundances is confirmed in terms of both surface concentration and vertical column, whereas corresponding SO2 changes are found to be marginal and not statistically significant, indicating that the decline of SO2 was more tied to natural or random variability rather than externally forced. To explain the contrasted responses of NO2 and SO2 during the APEC summit, short-term variations of these species are further placed in the context of a longer term perspective, which reveals a striking contrast in the pathways of the secular tendency in NO2 and SO2 emissions and corresponding measured abundances of both pollutants. On the one hand, NO2 emissions exhibit a sharp rise by 30%-50% from 2006-2010 to 2011-2014; on the other hand, SO2 emissions have undergone a gradual decrease in the last decade and have currently returned to their pre-2000 level. Therefore, short-term control measures are expected to be more effective in reducing the levels of NO2 than SO2.

AS04-D4-PM2-325B-013 (AS04-A053)
Modeling Studies of Haze in China: Emissions, Processes, Transport, and its Climatic Effect
Xiaoyan MA1#+, Tong SHA2
1 Nanjing University of Information Science , China, 2 Nanjing University of Information Science & Technology, China
#Corresponding author: +Presenter

Frequent haze event has become a serious problem in China. In order to improve our understanding of the processes that control the formation and fate of haze events, we conducted a number of numerical studies based on WRF-Chem model simulations. The impact of emission on the simulated air pollutants are firstly explored, by employing different emission inventories such as INTEX-B, MEIC, as well as GlobEmission, which is either from bottom-up or up-bottom approaches. The resulted air pollutants over the heavy polluted regions in China are discussed. Focusing on a heavy haze event occurred in East China, we explored the physical and chemical processes by comparing the modelled with observed air pollutants, attempting to attribute the possible reasons of the discrepancies between the simulations and observations, including local chemical formation and long range transport. Finally, the impact of air pollutants on radiation and atmospheric stability is discussed.

AS04-D4-PM2-325B-014 (AS04-A059)
More VOC Controls are Needed in Fighting Increasing Summer Ozone in China
Qi YING1#+, Peng WANG2, Hongliang ZHANG3, Jianlin HU4
1 Texas A and M University, United States, 2 Texas A&M University, United States, 3 Louisiana State University, United States, 4 Nanjing University of Information Science & Technology, China
#Corresponding author: +Presenter

Previous emission controls of NOx and VOCs in China were mainly aimed at reducing concentrations of airborne particulate matter (PM). In recent years, a steadily increase of ozone concentrations in many urban areas are observed by ground and satellite instruments. A complete source apportionment study of ozone is needed so that future emission control measures can be designed to benefit both ozone and PM reductions. In this study, an improved ozone source apportionment technique was developed. In contrast to traditional methods that divide ozone formation into NOx and VOC-limited regimes, the improved approach included a new transition regime, in which ozone formation is sensitive to both NOx and VOC emissions. The improved method is implemented into a modified version of the Community Multiscale Air Quality (CMAQ) model to assess the contributions to ozone due to residential, industrial, coal combustion, transportation and biogenic sources in the entire China. A significant fraction of the ozone is formed in the newly defined transition regime. Thus, more contributions of VOC sources to ozone formation is predicted in areas where traditionally considered as strictly NOx-limited. This suggests that more stringent VOC controls need to be implemented in these areas.

AS04-D4-PM2-325B-015 (AS04-A023)
Design of Ambient Air Quality Monitoring Stations Based on Human Health Aspects
Indian Institute of Technology Madras, India
#Corresponding author: +Presenter

Impact of highly polluted environment on human health is a widespread problem in all countries. Air quality index is one among the many parameters that captures the relationship between concentration of atmospheric pollutants and the related health effects. The air quality index that is calculated by the concerned authority has to be reported to the metropolitan areas of population more than 3,50,000, according to the document submitted by US EPA in May 2016 regarding daily air quality. The overall objective of placing an ambient air quality monitoring station is to measure the pollutants exceeding the standards. In this research paper, Air Quality Index method is adopted to design the ambient air quality monitoring stations to account for health impacts of air contaminants, effective sampling of pollutants and the population. Kriging method is used to get the spatial variations of air quality index with respect to criteria pollutants like particulate matter(PM) of size less than 10 micron and 2.5 micron, sulphur dioxide(SO2) and nitrogen dioxide (NO2) for Delhi city, India. Out of all criteria pollutants, it is found that the effect of particulate matter of size less than 10 micron(PM10) is relatively more on the design of ambient air quality monitoring stations and overall 35 stations are required for the entire city. In addition to that, people with respiratory or cardio-vascular diseases are found to be at higher risk due to air pollution.

AS04-D4-PM2-325B-016 (AS04-A011)
Study of the PM2.5 Growth Processes in Two Key Regions of China
Jinjin SUN1, Mingjie LIANG1, Jianlin HU1#+, Jingyi LI1, Qi YING2, Hongliang ZHANG3
1 Nanjing University of Information Science & Technology, China, 2 Texas A and M University, United States, 3 Louisiana State University, United States
#Corresponding author: +Presenter

Regional atmospheric environment pollution problems have become increasingly prominent in China in recent years, due to large amount of air pollutant emissions with the rapid economic development, the rapid growth of energy consumption and intensified urbanization. Specifically, the regions of Beijing-Tianjin-Hebei (BTH) and the Yangtze River Delta (YRD) are among the most economically developed and populated areas in China but also these regions are suffering extremely heavy air pollution. Fine particulate matter (PM2.5) is a major environmental problem in these two regions and greatly affects public health. A few case studies observed that PM2.5 could grow quickly in the two regions. The factors and processes that affect the growth processes still remain unclear.

In this study, we analyze the dynamic accumulation of PM2.5 using hourly concentration in the two regions. We focus on the PM2.5 growth processes from 35 to 150 µg/m3. We analyze all the growth processes in four years of 2013-2016 in 19 cities in the BTH and 21 cities in the YRD region. PM2.5 rising rates (PMRR) and dynamic growth duration (T) are calculated to illustrate the characteristics of the growth processes.

The results show that Beijing and Nanjing had 148 and 75 PM2.5 growth processes, respectively, during 2013-2016. The 4-year average PMRR in Beijing and Nanjing, is 5.28 µg/(m3.h), and 3.75 µg/(m3.h), respectively. Clear difference is observed between cities in BTH and YRD. Further analysis of the growth rates, associated meteorological conditions, chemical components of PM2.5 will be performed to investigate the controlling factors for different growth processes in different cities and regions.

AS04-D4-PM2-325B-017 (AS04-A075)
Long-Term Trends and Sptaial Variations of the PM2.5-Induced Premature Deaths in South and Southeast Asia During 1999-2014
Yusheng SHI#+
Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, China
#Corresponding author: +Presenter

Fine particulate matter (PM2.5) poses a potential threat to human health, including premature mortality under long-term exposure. Based on a long-term series of high-resolution (0.01° × 0.01°) satellite-retrieved PM2.5 concentrations, this study estimated the premature mortality attributable to PM2.5 in South and Southeast Asia (SSEA) from 1999 to 2014. Then, the long-term trends and spatial characteristics of PM2.5-induced premature deaths (1999–2014) were analyzed using trend analyses and standard deviation ellipses. The results show that PM2.5 concentrations increased in most areas of SSEA from 1999 to 2014 and exceeded the World Health Organization average annual limit of primary PM2.5 standards. Bangladesh, Pakistan and India experienced average PM2.5 values higher than the total average for SSEA. From 1999 to 2014, the entirety of SSEA exhibited an increased rate of 0.02 μg/m3/year on average. Bangladesh and Myanmar witnessed greater incremental rates of PM2.5 than India. The proportion of areas with PM2.5 concentrations exceeding 35 μg/m3 increased consistently, and the areas with PM2.5 concentrations below 15 μg/m3 decreased continuously. The estimated number of PM2.5-induced average annual premature deaths in SSEA was 1,447,000. The numbers increased from 1,179,400 in 1999 to 1,724,900 in 2014, with a growth rate of 38% and net increase of 545,500. Stroke and ischemic heart disease were the two principal contributors, accounting for 39% and 35% of the total, respectively. High values were concentrated in North India, Bangladesh, East Pakistan, and some metropolitan areas of Southeast Asia. An estimated 991,600 deaths in India was quantified (i.e., ~69% of the total premature deaths in SSEA). The long-term trends (1999–2014) of PM2.5-related premature mortality exhibited consistent incremental tendencies in all countries except Sri Lanka. The findings of this study suggest that strict controls of PM2.5 concentrations in SSEA are urgently required.

AS04 - Atmospheric Chemistry in Highly Polluted Environments: Emissions, Fate, and Impacts
Friday, June 08, 2018 | 325B | 08:30-10:30
AS04-D5-AM1-325B-018 (AS04-A067)
Aerosol-Boundary Layer Interaction and its Impact to Haze Pollution: Multi-Year Observational Evidences in North China
Xin HUANG#+, Aijun DING
Nanjing University, China
#Corresponding author: +Presenter

Atmospheric aerosols has been found to influence the development of planetary boundary layer (PBL) and hence enhance haze pollution in megacities. Previous works on aerosol-boundary layer interactions were mainly based on model simulation for short-term cases, so far there is a lack of multi-year observational evidences. In this study, based on multi-year radiosonde measurements, global reanalysis meteorological data together with ground-based measurement data, we give comprehensive observational evidences to demonstrate that aerosol-PBL feedback plays important role in enhancing haze pollution. We found that a significant heating existed in upper-PBL and free troposphere, with maximum air temperature change about 0.75 degree in average around 800-850 hPa, and a substantial dimming in the lower-PBL with the averaged air temperature reduction up to -2.75 degree during haze pollution episodes. A diagnose method based on Eulerian forward simulation together with backward trajectory calculation demonstrate that the upper-PBL heating was mainly induced by absorption aerosols. An index of the upper-PBL heating and lower-PBL dimming, named as HD-index, could well characterize the aerosol-PBL interactions and its impact on surface fine particle concentration during heavy pollution events.

AS04-D5-AM1-325B-019 (AS04-A048)
Aerosol Radiation Feedback Aggravates Heavy Haze in the North China Plain
Jiarui WU+, Guohui LI#, Junji CAO
Chinese Academy of Sciences, China
#Corresponding author: +Presenter

Atmospheric aerosols or fine particulate matters (PM2.5) scatter or absorb a fraction of the incoming solar radiation to cool or warm the atmosphere, decreasing surface temperature and altering atmospheric stability to further affect the dispersion of air pollutants in the planetary boundary layer (PBL). In the present study, simulations during persistent and heavy haze pollution episodes from 04 to 27 December 2015 in the North China Plain (NCP) have been performed using the WRF-CHEM model to comprehensively quantify contributions of the aerosol radiation feedback (ARF) to near-surface PM2.5mass concentrations. The WRF-CHEM model generally performs well in simulating the temporal variations and spatial distributions of air pollutants concentrations compared to observations at ambient monitoring sites in NCP. The simulated diurnal variations of aerosol species are also well consistent with the measurements in Beijing. Sensitivity studies have revealed that elevated levels of PM2.5concentrations during heavy haze episodes attenuate the incoming solar radiation down to the surface, cooling the temperature of the low-level atmosphere to suppress development of PBL and hinder the PM2.5 dispersion in the vertical direction and consequently perturbing wind fields. During the PBL height (PBLH) peak time, the PBLH generally decreases linearly with the increase of the PM2.5 concentration due to the ARF. Furthermore, when the near-surface PM2.5 concentration is less than around 75 μg m-3, the ARF generally reduces the PM2.5 concentration due to the resultant perturbation of wind fields. However, when the near-surface PM2.5 mass concentration increases from around 75 to several hundred μg m-3, the ARF enhances the PM2.5 contribution by up to 25% in NCP.

AS04-D5-AM1-325B-021 (AS04-A014)
Characteristics of Solar Radiation of China's Three Major Economic Regions and its Relationship with O3 and PM2.5 in the Past 10 Years
Xuejiao DENG#+
China Meteorological Administration, China
#Corresponding author: +Presenter

Based on the daily radiation datasets from 2007 to 2016 from the ground meteorological observation stations and the daily observation data from 2014 to 2016 from China’s air quality online monitoring platform, the paper analyzes the annual and seasonal variations of global solar radiation(GSR) in recent 10 years and the monthly variation of GSR, the maximum 8 hour average ozone(O3_8h_max) and fine particles(PM2.5) in recent 3 years in Beijing-Tianjin-Hebei(BTH),the Yangtze River Delta(YRD) and the Pearl River Delta(PRD). The relationship among  PM2.5,O3_8h_max and GSR by the classification statistics of different factors and intensity grades are discussed. The results show that:(1)GSR in BTH has increased significantly in recent 10 years, Spring GSR in BTH and summer GSR in PRD have increased significantly meanwhile.(2)The annual frequency of PM2.5 pollution process in the three major economic regions has been decreasing year by year, and decreasing from north to south. The annual frequency of O3 pollution process has decreased first and then increased temporally, which in BTH is more than in YRD and PRD spatially.(3)The correlation coefficients between O3_8h_max and GSR in the three economic regions are all above 0.71, and which means a strong positive correlation.(4)The linear fitting effect of O3_8h_max and PM2.5 under different GSR in the three economic regions is generally bad, and only shows a better positive correlation when GSR is more than  22MJ*m-2 in BTH and PRD. The linear fitting effect of O3_8h_max and GSR under different PM2.5 concentrations in the three economic regions is good, reflecting a strong positive correlation. The goodness of fit reaches maximum and the correlation coefficient improves significantly when PM2.5 concentration is more than 75 μg*m-3.The tendency of the line fitting increases with the increase of PM2.5 interval.

AS04-D5-AM1-325B-022 (AS04-A054)
Characteristics of Black-Carbon Containing Particles: Comparisons Between Very Clean and Highly Polluted Environments
Xinlei GE#+, Junfeng WANG
Nanjing University of Information Science & Technology, China
#Corresponding author: +Presenter

Refractory black carbon (rBC) aerosol is a very important climate forcer, and its impacts are greatly influenced by the species associated with rBC cores. However, relevant knowledge is lacking due to scarcity of surface observations. Here we present highly time-resolved measurement results of rBC and its coating species at a high altitude remote site in central TP (4730 m a.s.l), and in urban Beijing, China, respectively, by using an Aerodyne soot particle aerosol mass spectrometer (SP-AMS), which exclusively measured rBC-containing particles only. Such two cases represent the very clean and highly polluted environments. We found that the rBC over TP was overall thickly coated with an average mass ratio of coating to rBC (RBC) of ~7.7, and the coating species were predominantly secondary in nature, mainly produced by photochemical reactions. Interestingly, we found that the thickly coated rBC was less oxygenated than the thinly coated rBC, mainly due to the influence of a transported biomass burning organic aerosol (BBOA). This BBOA was relatively fresh but able to form very thick coating on rBC. On the other hand, rBC-containing particles in urban Beijing were overall associated with thinner coating, and the organic coating had diverse sources including both primary and secondary origins. We also discussed the light absorption enhancement due to the coating under these two cases.

AS04 - Atmospheric Chemistry in Highly Polluted Environments: Emissions, Fate, and Impacts
Friday, June 08, 2018 | 325B | 11:00-12:30
AS04-D5-AM2-325B-023 (AS04-A021)
Distribution and Sources of Air Pollutants in the North China Plain Based on On-Road Mobile Measurements
Tong ZHU1#+, Yi ZHU1, Junxia WANG1, Yingru LI1, Yiqun HAN1, Jiping ZHANG2, Jun LIU3
1 Peking University, China, 2 Institute of Atmospheric Physics, China, 3 International Institute for Applied Systems Analysis, China
#Corresponding author: +Presenter

The North China Plain (NCP) has been experiencing severe air pollution problems with rapid economic growth and urbanisation. Many field and model studies have examined the distribution of air pollutants in the NCP, but convincing results have not been achieved mainly due to a lack of direct measurements of pollutants over large areas. Here, we employed a mobile laboratory to observe the main air pollutants in a large part of the NCP from June 11 to July 15, 2013. High median concentrations of sulphur dioxide (SO2) (12 ppb), nitrogen oxides (NOx) (NO+NO2; 452 ppb), carbon monoxide (CO) (956 ppb), black carbon (BC; 5.5 μg m-3) and ultrafine particles (28350 cm-3) were measured. Most of the high values, i.e., 95 percentile concentrations, were distributed near large cities, suggesting the influence of local emissions. In addition, we analysed the regional transport of SO2 and CO, relatively long-lived pollutants, based on our mobile observations together with wind field and satellite data analyses. Our results suggested that, for border areas of the NCP, wind from outside would have a diluting effect on pollutants, while south winds would bring in pollutants accumulated during transport through other parts of the NCP. For the central NCP, the concentrations of pollutants were likely to remain at high levels, partly due to the influence of regional transport by prevalent south–north winds over the NCP and partly by local emissions.

AS04-D5-AM2-325B-024 (AS04-A016)
Global Sources of Ozone over China in the Context of Globalizing Air Pollution
Jintai LIN#+, Yingying YAN, Ruijing NI, Lulu CHEN
Peking University, China
#Corresponding author: +Presenter

China is known as a key source region of tropospheric ozone, and its ambient ozone concentration has been growing rapidly over the past few years. Yet much less unknown is the global sources of ozone over China through complex inter-regional linkage via atmospheric and socioeconomic mechanisms. As ozone and precursors can be transported in the atmosphere over long distances, regional ozone is linked to emissions worldwide. Furthermore, the globalization of economy and trade allows products consumed in one region to be produced in other regions, which implicitly leads to substantial geographical shift in emissions. This is a particularly important emission driver for China, the “world factory”. The coupling of atmospheric transport and economic trade requires re-thinking of the sources of regional ozone pollution, which also requires advanced atmospheric modeling, measurement, economic-emission analysis under an interdisciplinary framework. This paper will demonstrate that, due to the effect of atmospheric transport and economic trade, ozone over China is attributable to emissions, economic production and consumption worldwide. Our results call for much improved global cooperation to effectively mitigate regional pollution.

AS04-D5-AM2-325B-025 (AS04-A029)
Probable Source Region and Associated Health Risk due to PM2.5 in Indian Cities
Shovan SAHU1+, Hao GUO2, Hongliang ZHANG2, Jianlin HU3, Qi YING4, Sri H. KOTA1#
1 Indian Institute of Technology Guwahati, India, 2 Louisiana State University, United States, 3 Nanjing University of Information Science & Technology, China, 4 Texas A and M University, United States
#Corresponding author: +Presenter

The current study intends to identify potential source region of high PM2.5 concentration and associated health risk using 72-hr air mass back trajectories analysis during 2015-2016 in eight Indian cities viz. Delhi, Lucknow, Patna, Kolkata, Mumbai, Hyderabad, Chennai and Bangalore, covering different parts of the country. Health risk associated with a trajectory was estimated using integrated risk function. Polar plots and k-means clustering was used to identify probable source region for each city in different seasons. Analysis indicates that apart from Delhi, local source control could result in significant reductions in PM2.5 in India. Risk of Stroke was highest followed by lung cancer, chronic obstructive pulmonary disease and ischemic heart disease in all the cities. PM2.5 concentration and health risk in Delhi and Lucknow (54.53% and 65.62% respectively) was primarily contributed from Uttar Pradesh, Punjab and Haryana. Similarly, Uttar Pradesh and Bihar (61.17%), West Bengal and Indian Ocean (49.45%) were the major contributors in Patna and Kolkata, respectively. Indian Ocean contributed significantly to elevated levels of PM2.5 in western and southern cities, Mumbai (61.72%), Chennai (79.51%), Hyderabad (38.55%) and Bangalore (60.61%). Significant contribution of neighbouring countries towards elevated PM2.5 concentrations in northern and eastern India was observed during winter and post-monsoon. In winter, risk due to stroke from Pakistan to Delhi, Nepal and Pakistan to Lucknow and Patna, and Bangladesh to Kolkata was greater than 2.12.

Poster Presentations

  AS04-D1-EVE-P-027 (AS04-A005)
Constraining East Asian CO2 Emissions with GOSAT Retrievals: Methods and Policy Implications
Changsub SHIM#+
Korea Environment Institute, South Korea
#Corresponding author: +Presenter

The world largest CO2 emissions are from East Asia. However, there are large uncertainties in COemissions, mainly because of imperfections in bottom-up emissions statistics and a lack of observations for validating emission fluxes, particularly over China. Here we tried to constrain East Asian CO2 emissions with GOSAT retrievals applying 4-Dvar GEOS-Chem and its adjoint model. We applied the inversion to only the cold season in 2009 (Nov. and Dec.) since the summer monsoon and greater transboundary impacts in spring and fall greatly reduced the GOSAT retrievals. Based on our results, the a posteriori COemissions over East Asia (mainly China, Korea and Japan) higher by 10 – 50%, particularly mid-eastern China shows intensively higher in a posteriori emissions, where the Chinese government is recently focusing on mitigating the air pollutants. In another hand, a posteriori emissions from Southern China over lower 10 – 25%.

A posteriori emissions in South Korea and some cites in Japan are higher by 25~50%, which is also higher than the emission estimates by the mass-balance approach. These estimates will be refined by testing the cost function reduction depending on the relevant optimization parameters and uncertainties. This study will help understand the quantitative information on anthropogenic CO2 emissions over East Asia and will give policy implications for the mitigation targets

  AS04-D1-EVE-P-028 (AS04-A006)
Analysis of Regional Contribution to PM2.5 in Busan, Korea Using CAMx PAST - May 2017 Case Study -
Woo-Sik JUNG1#+, W. G. DO2
1 Inje University, South Korea, 2 Busan Metropolitan City Institute of Health and Environment, South Korea
#Corresponding author: +Presenter

The main sources of PM2.5 were initially internal industrial facilities or automobiles, but because Korea is located below China, pollutants emitted from the eastern region of China have also been identified as having a significant impact. As such, PM2.5 has been produced by various sources through complex processes, and effective reduction measures can be established only by determining the contribution rate of constituents by region. In this study, a three-dimensional, numerical air quality model, the Comprehensive Air Quality Model with Extensions (CAMx), was coupled with Particulate Matter Source Apportionment Technology (PSAT) to analyze region and source category contributions to PM2.5 content and related chemical components. This research took place in Busan, Korea, during May 2017 with a goal of setting reduction measure priorities. PM2.5 concentration in Busan was 26 μg/m3 in 2015, 27 in 2016, and showed an increasing trend of exceeding NAAQS (below 25μg/m3). This study also used a WRF-CAMx modeling system, which produced results in agreement with the observations completed, confirming reliability. Major PM2.5 components included sulfate (23.6%), followed by nitrate (12.7%) and ammonium (12.4%), so more than 40% of PM2.5 content in Busan was generated by secondary reactions. Contributions to PM2.5 content in Busan from foreign sources including China represented 46.0%, which was similar to that of domestic sources, 50.6%. This implies it would be difficult to reduce the PM2.5 in Busan only by managing sources in Korea. These results indicate it is necessary to control not only direct sources but also precursors of secondary reactions to reduce PM2.5. It is also necessary to take diplomatic measures to manage emission sources both at home and abroad.

This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education(2017R1D1A3B03036152).

  AS04-D1-EVE-P-029 (AS04-A012)
Modeling Study of Sensitivity of Surface Ozone and Fine Particulate Matter to Meteorology in China
Zhihao SHI1, Jianlin HU1#+, Jingyi LI1, Qi YING2, Hongliang ZHANG3
1 Nanjing University of Information Science & Technology, China, 2 Texas A and M University, United States, 3 Louisiana State University, United States
#Corresponding author: +Presenter

China has been suffering from severe regional atmospheric environment pollution problems, characterized by high concentrations of surface ozone (O3) and fine particulate matter (PM2.5). Severe air pollution problems have caused damages to public health, decreased ambient air quality, and caused changes in climate. Meteorological conditions play very important roles in the formation of O3 and PM2.5 pollution. This study aims to analyze how sensitive the O3 and PM2.5 concentrations in different regions of China are to the changes in different meteorological parameters. In this study, air quality model CMAQ is used to simulate the air quality in China in January and July of 2013. We perturb seven major meteorological parameters, i.e., wind speed, wind direction, temperature, humidity, boundary layer height, precipitation, and cloud cover, and then simulate the changes in O3 and PM2.5 concentrations. The results indicate that different meteorological parameters have distinct impacts on O3 and PM2.5 concentrations in China. Temperature has the greatest impact on O3 concentrations, and positively correlated with daily maximum 8 hour average O3, except in Guangzhou and Xi’an. Humidity has relatively small impact on O3. Regionally, the O3 concentrations in July will increase with the temperature in most regions of China, but the O3 concentrations will decrease with the temperature in Southwest and Northeast part of China. Temperature increase in July will decrease the concentrations of nitrate and ammonium PM2.5. Wind speed, boundary layer height and humidity also have important effects on PM2.5. Further analysis will identify the key meteorological parameters that have significant impacts on the extreme O3 and PM2.5 concentrations in China and the results will have important implications for the impacts of climate change on the air quality in China.

  AS04-D1-EVE-P-030 (AS04-A019)
Study of the Relationship Between Aerosols Diffusion and Sedimentation Characteristics by Using Scanning LIDAR and Micro-Sensors
Chih-Wei CHIANG#+, Hong-Wei CHIANG, Huann-Ming CHOU, Tien-Ying CHUNG, Wen-Ching LIN
Kun Shan University, Taiwan
#Corresponding author: +Presenter

In recent years, people pay more and more attention of aerosols, especially PM2.5, due to the aerosols not only infect the respiratory tract, but also endanger the physical. The aerosols are mainly produced from industrial waste gas, vehicles, agricultural waste burning, sea salt and dust etc., caused the deterioration of air quality and formation of complex relationship with atmospheric condition. The objective of this paper is to make an attempt for understanding the spatial distribution of aerosols and distinguishing correlations between aerosols, atmospheric conditions and air quality by using scanning Lidar, air quality monitoring sensors and artificial particle generator. In addition, the theoretical model also be discussed. Details will be presented in the upcoming symposium.

  AS04-D1-EVE-P-031 (AS04-A024)
Source Apportionment and Health Risks of Polycyclic Aromatic Hydrocarbons (PAHs) in China
Fenglin HAN1, Jie ZHANG2, Jianlin HU3, Qi YING4, Hongliang ZHANG1#+
1 Louisiana State University, United States, 2 Texas A&M University, United States, 3 Nanjing University of Information Science & Technology, China, 4 Texas A and M University, United States
#Corresponding author: +Presenter

Polycyclic aromatic hydrocarbons (PAHs) in the atmosphere are of significant concern due to their high toxicity and adverse health effects. China is the largest contributor of global PAHs but limited PAHs measurements are insufficient to gain a complete understanding of ambient PAH levels. This study simulates the concentrations of PAHs in China and identifies the major emission sources. Annual anthropogenic emissions of CO, NOx, SO2, non-methane volatile organic compounds (NMVOC), PM2.5, PM10, EC and OC with a spatial resolution of 0.1° × 0.1° were downloaded from Emissions Database for Global Atmospheric Research (EDGAR) version 4.3. Representative profiles for each EDGAR source category were taken from the SPECIATE 4.3 database. Biogenic emissions were generated using the Model for Emissions of Gases and Aerosols from Nature (MEGAN) v2.1. Open biomass burning emissions were generated from the Fire Inventory from NCAR (FINN). PAH emissions of 16 priority PAH species directly associated with health risks were generated from the global high-resolution PKU-FUEL-2007 inventory. The estimated emissions were then applied to simulate ambient concentrations of PAHs in China for January, April, July and October 2013 using the Community Multiscale Air Quality (CMAQ) model (v5.0.1). Through the formation, transport and deposition of PAHs species, the concentrations of PAHs species in gas phase and particulate phase were obtained. The spatial and temporal variations were analyzed and contributions of both local and regional major sources were quantified. This study provides important information for the prevention and treatment of PAHs in China.

  AS04-D1-EVE-P-032 (AS04-A025)
Dome Effect of Black Carbon and its Key Influencing Factors: A One-Dimensional Modelling Study
Zilin WANG#+, Xin HUANG, Aijun DING
Nanjing University, China
#Corresponding author: +Presenter

Black carbon (BC) has been identified to play a critical role in aerosol-planet boundary layer (PBL) interaction and further deterioration of near-surface air pollution in megacities, which has been named as its “dome effect”. However, the impacts of key factors that influence this effect, such as the vertical distribution and aging processes of BC, and also the underlying land surface, have not been quantitatively explored yet. Here, based on available in-situ measurements of meteorology and atmospheric aerosols together with the meteorology-chemistry online coupled model, WRF-Chem, we conduct a set of parallel simulations to quantify the roles of these factors in influencing the BC’s dome effect and surface haze pollution, and discuss the main implications of the results to air pollution mitigation in China. We found that the impact of BC on PBL is very sensitive to the altitude of aerosol layer. The upper level BC, especially those near the capping inversion, is more essential in suppressing the PBL height and weakening the turbulence mixing. The dome effect of BC tends to be significantly intensified as BC aerosol mixed with scattering aerosols during winter haze events, resulting in a decrease of PBL height by more than 25%. In addition, the dome effect is more substantial (up to 15%) in rural areas than that in the urban areas with the same BC loading, indicating an unexpected regional impact of such kind of effect to air quality in countryside. This study suggests that China’s regional air pollution would greatly benefit from BC emission reductions, especially those from the elevated sources from the chimneys and also the domestic combustions in rural areas, through weakening the aerosol-boundary layer interactions that triggered by BC.

  AS04-D1-EVE-P-033 (AS04-A026)
Characterization of Ambient Air Pollution and Health Burden of Fine Particulate Matter in Nanjing
Dongyang NIE#+, Mindong CHEN, Xinlei GE, Yun WU
Nanjing University of Information Science & Technology, China
#Corresponding author: +Presenter

With the rapid industrialization and urbanization, Nanjing faced with exceptionally serious air problem, and the adverse health effects due to air pollution has become a matter of public concern. In this study, the hourly and daily concentrations of air pollutants and meteorological data in Nanjing from March, 2014 to February, 2017 were used to analyse the temporal characterization and the relationship between them. Then the integrated exposure-response (IER) model was applied to assess the mortality and years of life lost (YLL) due to PM2.5. The mortality benefits were estimated in the scenarios when meeting the World Health Organization (WHO) Air Quality Guidelines (AQG) and three interim targets (ITs). The results showed that the pollutants decreased during the study period, expect for CO and O3. The concentrations of pollutants varied in years and seasons can be explained by the emissions, chemical reactions and meteorological conditions. The attributable fractions (AF) of PM2.5 for chronic obstructive pulmonary disease (COPD), lung cancer (LC), ischemic heart disease (IHD), and Stroke are 23% (CI95 12−32%), 29% (CI95 11−40%), 30% (CI95 21−48%), 46% (CI95 17−57%) and 20% (CI9510−29%), 24% (CI95 8−35%), 28% (CI95 19−44%), 43% (CI95 15−55%),in 2014 and 2015, respectively. The total deaths in Nanjing due to PM2.5 are 12055 and 10771 in 2014 and 2015, respectively. Long-term exposure to PM2.5 contributed to 98802.2 and 90399.4 years lost in 2014, 2015, respectively. The males and older people are under the high health risk. When the PM2.5 concentrations meeting the AQG (10 μg/m3), about 80% of the premature deaths will be avoided, indicating much higher health benefits could be achieved if Nanjing adopted more stringent guidelines.

  AS04-D1-EVE-P-034 (AS04-A027)
Characteristic Analysis of Precipitation and Wet Removal of Aerosols in Chengdu
Chao WANG1#+, Tiangui XIAO1, Luo QIN2, Libin WU2, Xiaohang WEN1, Ding CHEN1
1 Chengdu University of Information Technology, China, 2 Wenjiang Meteorological Bureau, China
#Corresponding author: +Presenter

The wet removal of precipitation is an important sink of atmospheric aerosol. To studying the characteristics of precipitation and its impact on particle in Chengdu, the data of precipitation and particle concentration were used, and shows that: the yearly average of precipitation in Chengdu is 872.14mm, and had an increasing trend; the distribution of daily precipitation was concentrated at 0.1-3.0mm, the precipitation in a year was uneven distributed, the maximum value in JUL and the minimum in JAN, and the characteristics were fitted well by Lorenz curve; The daily variations of precipitation were remarkable, it`s more in daytime than night , and its characteristics can be fitted well by the polynomial curve; the purification efficiency to PM10, PM2.5 is 32.5%、29.7% respective, in spring is more efficiency than autumn > summer > winter; The characteristics of the impact on the particulates by Precipitation were fitted well by the power exponents, Lorenz curve, polynomial and logarithmic curve.

Acknowledgements: This study was supported by National Natural Science Foundation ofChina Fund Project (91337215,41575066), Wenjiang District Science and technology project(WJKJXM),Study on the control mechanism of fog and haze in Sichuan province-2015.

  AS04-D1-EVE-P-035 (AS04-A030)
Estimating Ground Level PM2.5 Concentrations and Associated Health Risk Using Aerosol Optical Depth and Meteorological Parameters in Indian Cities
Shovan SAHU1+, Venkatesh CHEJARLA1, Hao GUO2, Rishikesh BHARTI1, Hongliang ZHANG2, Jianlin HU3, Qi YING4, Sri H. KOTA1#
1 Indian Institute of Technology Guwahati, India, 2 Louisiana State University, United States, 3 Nanjing University of Information Science & Technology, China, 4 Texas A and M University, United States
#Corresponding author: +Presenter

The study estimates health risk due to PM2.5 using Aerosol Optical Depth (AOD) and Angstrom Exponent (AE) measured by Moderate-resolution Imaging Spectroradiometer (MODIS) data and meteorological parameters from Weather Research Forecasting (WRF) model. Four different models were used to predict ground based PM2.5 concentrations at eight Indian cities, which represent different parts of the country, i.e. Delhi and Lucknow in the north, Patna and Kolkata in the east, Bangalore, Chennai and Hyderabad in the south and Mumbai in the west. Model-1 uses linear regression technique to calculate PM2.5 from AOD data. Models 2 and 3 use generalized additive model (GAM) with meteorological parameters viz. wind speed (WS), temperature, relative humidity (RH) and mixing layer height (HPBL) in addition to AOD as independent variables. While model 2 assumes Poisson distribution of the input parameters, model 3 uses normal distribution. Model 4 is similar to models 2 and 3 but developed in GIS environment to predict spatial variations of PM2.5. Models using meteorological parameters as independent variables showed better performance. Integrated risk function was used to estimate health risk due to predicted PM2.5 concentrations in entire India.

  AS04-D1-EVE-P-036 (AS04-A035)
Guided Sampling for Volatile Organic Compounds During Biomass Burning Events in Indochina
Chang-Feng OU-YANG1#+, Chih-Chung CHANG2, Jia-Lin WANG1, Si-Chee TSAY3, Sheng-Hsiang WANG1, Gang-Jei FAN1, Kai-Hsien CHI4, Somporn CHANTARA5, Neng-Huei LIN1
1 National Central University, Taiwan, 2 Academia Sinica, Taiwan, 3 NASA Goddard Space Flight Center, United States, 4 National Yang-Ming University, Taiwan, 5 Chiang Mai University, Thailand
#Corresponding author: +Presenter

Biomass burning (BB) in Indochina is believed to be a major source of air pollutants during springtime, which can perturb the air composition and quality in the East Asia region and even in the globe scale. This study investigates the characteristics of VOCs released in the highly polluted source region near the border between Thailand and Myanmar. Twenty-six whole air samples were collected using guided sampling technique with carbon monoxide (CO) served as the trigger agent to capture significant BB plumes at Doi Ang Khang (DAK, 19.93°N, 99.05°E, 1536 m a.s.l.) in March, 2014. The threshold was set at 1 ppmv of CO. Three samples were collected manually after the campaign and considered as background value in this season without BB influences. The air samples were subsequently analyzed in-lab by gas chromatography/mass spectrometry/flame ionization detection (GC/MS/FID) and cavity ring-down spectrometry (CRDS) for VOCs and greenhouse gases, respectively. Modified combustion efficiency (MCE) was calculated for each sample to assess its relationship between VOCs. However, most VOCs does not response to MCE except for ketones which showed an anti-correlation with MCE, implying that ketones were produced preferably in smoldering condition. To post a contrast to the BB VOCs, 24 roadside samples collected in Taipei (TPE, within 24.95 – 25.11°N, 121.45 – 121.65°E) in April 2014 were used. Although the average concentration of total VOCs measured at DAK (69.0 ppbv) was only ~62% of the TPE samples (110.6 ppbv), significant contribution from ketones (~16.7%) was found in the BB samples compared to those collected in urban traffic environment (~5.7%), revealing a possible pathway to produce oxygen-rich species. Ethyne was found to exhibit good correlation with CO (R2 = 0.82) with a mean ethyne/CO of 3.95 ppbv/ppmv, indicating a distinct emission signature of BB in the Indochinese region.

  AS04-D1-EVE-P-037 (AS04-A036)
Urban Heat Island Affected by Fine Particles in Nanjing, China
Hao WU#+, Tijian WANG
Nanjing University, China
#Corresponding author: +Presenter

Atmospheric aerosol particles (especially particles with aerodynamic diameters equal to or less than 2.5 μm, called PM2.5) can affect the surface energy balance and atmospheric heating rates and thus may impact the intensity of urban heat islands. In this paper, the effect of fine particles on the urban heat island intensity in Nanjing (a mega city near Shanghai)was investigated via the analysis of observational data and numerical modelling. The observations showed that higher PM2.5 concentrations over the urban area corresponded to lower urban heat island (UHI) intensities, especially during the day. Under heavily polluted conditions, the UHI intensity was reduced by up to 1 K. The numerical simulation results confirmed the weakening of the UHI intensity due to PM2.5 via the higher PM2.5 concentrations present in the urban region than those in the suburban areas. PM2.5 had extinction effects on the heat island and had an apparent difference in different seasons.The effects of the fine particles on the UHI reduction were limited to the lowest 500–1000 m. The daily range of the surface air temperature was also reduced by up to 1.1 K due to the particles’ radiative effects. In summary, PM2.5 noticeably impacts UHI intensity, which should be considered in future studies on air pollution and urban climates.

  AS04-D1-EVE-P-038 (AS04-A039)
Regional Severe Particle Pollution and Associated Synoptic Weather Patterns over Yangtze River Delta, China
Lei SHU+, Tijian WANG#, Min XIE
Nanjing University, China
#Corresponding author: +Presenter

Regional air pollution is significantly associated with dominant weather systems. In this study, the relationship between particle pollution over Yangtze River Delta (YRD) and weather patterns is investigated. Firstly, pollution characteristics of particles are studied using surface monitoring data (PM2.5 and PM10) in 16 cities and Terra/MODIS aerosol optical depth (AOD) products from December 2013 to November 2014. The results show that YRD suffers from heavy particle loading, with an annual mean AOD of 0.71. Higher particle levels are found in Jiangsu Province, with highest PM2.5 (79 μg/m3) and PM10 (130 μg/m3) in Nanjing. High PM2.5/PM10 ratios also indicate PM2.5 fraction is overwhelmingly dominant in PM10. Secondly, synoptic weather classification is conducted using the sums-of-squares technique, and five typical synoptic patterns are objectively identified. Finally, synthetic analysis of meteorological fields and backward trajectories are applied to further clarify how these patterns impact particle pollution. It shows that the relative position of YRD to the anti-cyclonic system exerts significant impacts on the air quality of YRD. When located at the rear of the East Asian trough, YRD is notably influenced by polluted air from northern and southern regions. Significant downward motion results in stable weather conditions, thereby hindering the diffusion of pollutants. This pattern is regarded to be responsible for most large-scale regional PM2.5 (70.4%) and PM10 (78.3%) pollution episodes, with regional mean PM2.5 (75.9±49.9 μg/m3), PM10 (116.5±66.9 μg/m3) and AOD (0.74) in YRD. Strong wind and clean marine air masses play crucial roles in the mitigation of pollution in YRD. Especially when affected by cyclonic systems or oceanic circulation, the air in YRD has a smaller chance of being polluted. The establishment of potential links between different levels of particle pollution and predominant synoptic patterns can provide insight into formulating pollution control and mitigation strategies.

  AS04-D1-EVE-P-039 (AS04-A040)
Regional Source Apportionment of PM2.5 in North India Using a Source-Oriented Regional Air Quality Model
Hao GUO1+, Shovan SAHU2, Sri H. KOTA2, Jianlin HU3, Qi YING4, Wenye DENG5, Hongliang ZHANG1#
1 Louisiana State University, United States, 2 Indian Institute of Technology Guwahati, India, 3 Nanjing University of Information Science & Technology, China, 4 Texas A and M University, United States, 5 Xinjiang Academy of Environmental Protection Science, China
#Corresponding author: +Presenter

North India has been suffered from high concentration of particulate matter (PM) in past decades especially at its capital, Delhi. In this study, a source-oriented Community Multi-scale Air Quality (CMAQ) model was applied to determine contributions of different regions to PM2.5 concentrations in Delhi and North India. Emissions from 9 source regions including Delhi, Haryana & Rajasthan, U. Pradesh & Uttarkhand, H. Prad & Punjab, Central India, West India, South India, East & Northeast India, and Outside India were tracked simultaneously in 2015. The results show four cities in North India have a high concentration of PM2.5 with more than 70% of local sources, Central India and West India contribute to ~20%. Time series of daily regional contributions in four cities at North India also indicate stronger and more frequent inter-regional transport in winter than in summer.

Transport of primary PM and secondary inorganic aerosol from other regions to Delhi is also analyzed. About 80% of PM2.5 is from local sources in Delhi and adjacent states contribute ~ 30 μg/m3 to total PM2.5. This study determines the contributions of regional transport to total PM2.5 in Delhi and North India, and provides valuable information for designing effective control strategies.

  AS04-D1-EVE-P-040 (AS04-A042)
Effects of Climate Change and Emission Scenarios on Air Pollution in Louisiana
Hao GUO+, Hongliang ZHANG#
Louisiana State University, United States
#Corresponding author: +Presenter

With the potential growth of industries and population in Louisiana, increase of air pollutants emissions is expected and will result in high pollution levels in future in addition to climate change. This study investigates the effects of emission and climate change on concentrations of ozone and particulate matter (PM) in 2050 using the Community Multi-scale Air Quality (CMAQ) model. The current meteorology will be generated using Weather Research and Forecasting (WRF) model version 3.7.1 and the future meteorology will be generated using the same model under the Representative Concentration Pathways (RCP) 4.5, 6.0 and 8.5 emission scenario. The future emission scenarios will be developed based on the projection of US emission inventory in 2011 with proper factors to reflect the growth of industry and population and control strategies. The difference in spatial and temporal variations of air pollutants between 2011 and 2050 will be analyzed and the contributions of emission change and climate change will be quantified.

  AS04-D1-EVE-P-041 (AS04-A043)
Analysis of Air Qualities Using OMI Satellite and Aircraft Measurements over Korea
Hyeong-Ahn KWON1#+, Rokjin J. PARK1, Gonzalo GONZÁLEZ ABAD2, Christopher MILLER3, Kelly CHANCE2
1 Seoul National University, South Korea, 2 Harvard-Smithsonian Center for Astrophysics, United States, 3 Harvard University, United States
#Corresponding author: +Presenter

A Geostationary Environment Monitoring Spectrometer (GEMS) is planned to be launched by the Ministry of Environment in South Korea in 2019. Its finer spatial and temporal resolutions than those of sun-synchronous satellites enable us to monitor transboundary transports, hourly variations, and an increment or decrement of air pollutant emissions in East Asia. In this study, as a preparation for GEMS we examine OMI formaldehyde (HCHO) column measurements in Korea for 2005-2016 during which the values have increased by ~0.52E+15 molecules cm-2 per year for 2005-2011 and then have fluctuated since 2012. OMI glyoxal (CHOCHO) column densities also show weak positive trends over the period. The measurements of VOC oxidation products largely show a consistent trend with that of anthropogenic VOC emissions. However, nitrogen dioxide (NO2) column densities do not follow NOx emission trends over South Korea. In order to identify emission changes for 2005-2016 and the discrepancy between satellite observations and emissions, we conduct temporal oversampling of satellite data, which make fine spatial resolutions with a few km. Oversampled HCHO vertical columns for 2012-2016 are significantly higher than those for 2005-2011 over some regions, where local anthropogenic VOCs have increased. An analysis using oversampled HCHO, NO2, and CHOCHO helps us diagnose the dependency of O3 production on VOCs versus NOx. Finally, we also focus our analysis on aircraft observations for the KORUS-AQ campaign in May-June 2016 and examine similarities and differences with analysis using satellite data.

  AS04-D1-EVE-P-042 (AS04-A044)
Simulation of Atmospheric Transport of Hazardous Chemicals from Tianjin Explosion Accident with Flexpart
Hyuckjae LEE+, Myong-In LEE#, Chang-Keun SONG
Ulsan National Institute of Science and Technology, South Korea
#Corresponding author: +Presenter

On the August 12, 2015 at Tianjin Harbor, violent explosions and massive fires covered the warehouses and huge amount of hazardous chemicals were released into the atmosphere. Tons of hazardous chemicals were supposedly transported to the Korean peninsula, but the actual concentration level was detected under the minimum detectable amount. The simulation is conducted with FLEXible PARTicle dispersion model (FLEXPART) which is suitable for modeling framework for atmospheric dispersion of air pollutants. It simulates inconstant particle dispersions and turbulent wind fluctuations within three dimensional characteristics of plumes. We simulated for the Tianjin explosion case to determine potential pathways of substance plumes which is not exactly known. In this experiment, NCEP CFSv2 meteorological data is used and the simulated emission species are sodium cyanide(NaCN) and Potassium nitrate(KNO3). Horizontal resolution is 0.1º x 0.1º. The simulation period is from 23:30, 12 August 2015 to 24th August. We also consider that the concentration (x) represents the product of the atmospheric dilution (D.F) from the source to the receptor and the emission rate(Q). It can be assessing and estimating how hazardous chemicals are diluted during atmospheric dispersion from the starting location. As a result of simulation, chemical plumes were reaching to the Korean peninsula however highly diluted (1018~1019times) after the accident. We also find that total amounts of deposition are depending on molecular weight. For further study, we validate simulation results with observations of major pollutants (mainly NaCN, KNO3) by satellite datasets.

  AS04-D1-EVE-P-043 (AS04-A045)
Spatiotemporal Variability of Chemicals and Sources of Ambient Fine Particles in Korea
Jongbae HEO#+, Seung-Muk YI
Seoul National University, South Korea
#Corresponding author: +Presenter

There has been considerable progress in understanding the specific components and sources of ambient fine particles (PM2.5) responsible for observed human health effects. However, estimating true population health risk of PM2.5 exposure in urban environments is difficult due to considerable uncertantiy regarding the spatial variability of the components and sources within urban settings. This study was designed to evaulate spatial and temporal variations of the components and sources in Korea.

Twenty four hour integrated PM2.5 samples were collected on one in three day intervals from January 2013 through December 2016 at six of PM2.5 supersites in Korea (four urban sites, and two background sites). The PM2.5 samples were analyzed for major chemical components including organic carbon, elemental carbon, ions, and trace elements and the results were used in a positive matrix factorizaiton model to estimate source contributions to PM2.5 mass. Ten sources, including secondary sulfate, secondary nitrate, mobile, coal combustion, oil combustion, industry, biomass burning, roadway emission, soil, and sea salt, were identified across the sampling sites. Secondary inorganic aerosol (i.e. secondary sulfate and nitrate) was a major sources contributing to approximately 40% of the total PM2.5 mass and showed relatively homogeneous temporal trends in daily source contribution over the study area. Mobile and roadway emission sources showed samll spatial variability of daily contribution, whereas other sources (i.e. biomass burning, industry, oil combustion, and soil) showed large spatial variations in contributions.

The spatial and temporal characteristics of each of PM2.5 chemcals and sources were examined using summary statistics, correlation analysis, and coefficient of variation, as well as divergence analysis. The detailed results from the analyses will be discussed in the presentation.

  AS04-D1-EVE-P-044 (AS04-A051)
Heavy Haze Formation During Wintertime in the Guanzhong Basin, China: A Case Study
Xia LI1,2+, Guohui LI3#, Junji CAO3
1 Institute of Earth Environment,Chinese Academy of Sciences, China, 2 University of Chinese Academy of Sciences, China, 3 Chinese Academy of Sciences, China
#Corresponding author: +Presenter

The acceleration of industrialization and urbanization during the past several decades has seriously deteriorated the air quality in the Guanzhong Basin (GZB), Northwestern China. Although stringent emission control strategies have been implemented recently, heavy haze with high levels of fine particulate matters (PM2.5) frequently engulfs GZB, especially during wintertime. In the present study, persistent haze pollution episodes from 4 to 22 December 2016 in GZB are simulated using the WRF-CHEM model to investigate the heavy haze formation. The WRF-CHEM model reasonably well replicates the evolution of haze events and well reproduces the spatial distributions and temporal variations of the air pollutants mass concentrations against observations at monitoring sites in GZB. The diurnal variations of aerosol species are also in good agreement with the measurements in Xi’an and Xianyang. Organic and nitrate aerosols have constituted two major components of the PM2.5 in GZB. The sensitivity simulations indicate that besides the local emissions, the transboundary transport of non-GZB emissions also plays an important role in the heavy haze formation. During heavy haze pollution episodes, the prevailing easterly and/or northeasterly winds bring the air pollutants originated from Shanxi and Henan Province to GZB, contributing up to 30% of the near-surface PM2.5 concentrations. Our results suggest that the cooperative emission mitigation strategies with neighboring provinces are beneficial to the improvement of the air quality in GZB.

  AS04-D1-EVE-P-045 (AS04-A056)
Applying the Water Mist Washing Technology to Improve the Loss of Semi-Volatile Species of the in Situ Aerosol Composition Measurement
Yu-Chieh CHEN+, Shih-Yu CHANG#
Chung Shan Medical University, Taiwan
#Corresponding author: +Presenter

The in situ aerosol composition measurement with steam jet collecting system got on the laboratory experiments, indicated volatility losses from the hot droplets. Based on a number of inter-comparisons, the NH4+ concentration of the steam jet collecting system was underestimated by 15 ± 3% (Ma 2004). Takegawa et al. (2005) found that the NH4+ loss was evaluated by supplying pure NH4NO3 particles into the steam jet collecting system equipped with ion chromatography and was found to be 20%. In this study, the in situ air composition measuring equipment-2100 (ACME-2100) applied the water mist washing technology was developed for reducing the volatility losses, which can provide online measurements of concentrations of inorganic soluble gaseous and aerosol species.

The performance of ACME-2100 is evaluated by comparing with the traditional filter method. In the traditional filter method, aerosols were firstly collected on the filter by the PQ-200 sampler. Filters were extracted in deionized water and the extract analyzed for inorganic soluble ions. Comparing the concentrations of SO42-, NO3-, and NH4+ simultaneously measured by two method, the slops and intercepts of SO42-, NO3-, and NH4+ were respectively 1.03 and -0.33 mg m-3, 0.9 and 0.17 mg m-3, 1.13 and -1.95 mg m-3. The correlation values of SO42-, NO3-, and NH4+ were 0.91, 0.95, and 0.89. In general, there was a good agreement between the ACME-2100 and the filter measurements. Furthermore, according to the simultaneous measurement of the ACME-2100 and the steam jet collecting system, the NH4+/SO42- molar ratio was used to evaluate volatility loss of ammonium between two systems. The average NH4+/SO42- molar ratio of the steam jet collecting system and the ACME-2100 were 0.70 and 1.01, respectively. The discrepancy may be related with the volatility losses due to the hot droplets.

The primary results indicated that the ACME-2100 could supply reliable particulate sulfate, nitrate, and ammonium continuous data in field measurement without the underestimation of volatile components. And the ACME-2100 is proved useful in intensive and long-term observation for a wide range of pollution situations.

  AS04-D1-EVE-P-046 (AS04-A057)
The Investigation of Three-Dimensional Characteristics of Inorganic Soluble Ions in an Urban Micro-Environment
Yu-Chieh CHEN1+, Chih-Chung CHANG2, Wei-Nai CHEN2, Yu-Chen TSAI1, Lien-En HUANG1, Ya-Pang JHUANG1, Shih-Yu CHANG1#
1 Chung Shan Medical University, Taiwan, 2 Academia Sinica, Taiwan
#Corresponding author: +Presenter

In recent years, the development of unmanned aerial vehicles (UAVs) has become increasingly mature. The published studies indicated that there are great differences and variability in the research on the aerosol mass concentration, number concentration, size distribution, trace gases, optical characteristics and mixed transport mechanism of airflow at different vertical altitudes near the ground surface. However, no studies have been conducted on the measurement of the vertical distribution of the chemical species of the atmospheric aerosols in this micro-environment.

The measurement of the vertical distribution of the aerosol chemical species by UAV is limited by the short hovering time of the UAV. The concentration of the aerosol samples collected by the traditional filter method in a solution after extraction is often below the detection limit. In this study, a UAV and portable aerosol-sampling equipment were integrated into a platform. This novel technique can measure the vertical distribution of the aerosol chemical species in the near-surface micro-atmosphere. It is applied to research areas such as the assessment of the boundary layer height, the impact of turbulence and inversion temperature at different altitudes on the diffusion and transmission of air pollutants, and the physicochemical reaction mechanisms of an aerosol above and below the boundary layer.

The results of time-height measurements in this study show that in most cases, the ion species of the aerosol in the upper sky were higher than the value measured at 0 m above the ground surface. In some time periods, there was a turning point of the concentration value at different heights. Below the boundary layer, thermal turbulence increases the horizontal wind speed, which enhances the diffusion of air pollutants. The concentrations of total soluble inorganic ions in PM2.5 were decreased as the boundary layer height development. The stable atmospheric environment with low wind speed, observed above the boundary layer, was benefit to the formation and accumulation of secondary aerosols. The time series and vertical distribution of NH4+ concentration was similar to that of NO3- concentration, which indicated NH4NO3 was the one of major aerosol compositions in Taichung urban area.

  AS04-D1-EVE-P-047 (AS04-A058)
Seasonal Changes in Surface Ozone over South Korea
Hyun-Chae JUNG+, Byung-Kwon MOON#
Chonbuk National University, South Korea
#Corresponding author: +Presenter

Gradually increasing surface ozone (O3) concentrations in South Korea are a cause of public environmental concern. We examined changes in the timing of annual maximum South Korean O3 levels by fitting a sine function to data from 54 air-quality monitoring sites over a 10-year period (2005-2014). At 23 sites, annual peak concentrations appeared earlier in the year (E-sites), while at the other 31 they appeared later (L-sites). We attribute these differences to seasonal O3 changes: E-sites show a larger increase in O3 level in the spring than in the summer, while L-sites show a larger increase in the summer than in the spring. Furthermore, these shifts are significantly larger in magnitude than those reported for Europe and North America. We also examined one possible reason for these seasonal differences: the relationship between O3 and precursors such as NO2. The O3 increase in spring for the E-sites was associated with a decrease in NO2, likely related to a reduction in NOx titration. In contrast, L-sites were associated with relatively higher NO2 concentrations in springtime with more loss of O3 via NOx titration, leading to a shift in the seasonal cycle toward the end of the year. We suggest that shifts in the South Korean O3 seasonal cycle are due to changes in springtime NO2 levels; this should be tested further by modeling studies.


This research was supported by the Korea Ministry of Environment (MOE) as “Climate Change Correspondence Program.”

  AS04-D1-EVE-P-048 (AS04-A061)
Reassessing Ozone Incremental Reactivity Scales Using VOC Data from China
Qi YING1#+, Yuan CHEN2, Jianlin HU3, Hongliang ZHANG4
1 Texas A and M University, United States, 2 Texas A&M University, United States, 3 Nanjing University of Information Science & Technology, China, 4 Louisiana State University, United States
#Corresponding author: +Presenter

Ozone incremental reactivity (IR) scales for a large number of volatile organic compounds (VOCs) have been developed in the 1990s as a measure of the capability of these VOCs in producing tropospheric ozone. Emissions control measures for various VOCs are based on the emission rates of these VOCs and their ozone IR. These reactivity scales have been widely applied in many different areas for a time span of nearly three decades. However, the IR scales were determined in a photochemical box model with a base mixture of VOCs, which were meant to represent typical VOC concentrations in urban areas. While the photochemical box model used in the simulations have been updated frequently, the base VOC mixture remains unchanged, representing urban conditions in typical US cities 30 years ago. In this study, we apply a regional photochemical model with detailed representation of many VOCs to estimate the VOC mixture in major Chinese cities and use these predicted VOC concentrations as the base VOC mixture to calculate maximum incremental reactivity (MIR) scales of 54 major primary VOC species. We revealed that while the average MIR from the cities are generally similar to the ones developed using the old US mixture, there are significant variations in the IR values among different cities, suggesting that it is necessary to account for VOC base mixture differences when applying MIR values. As the model predicted VOC values can have large uncertainties, more field measurements for VOCs are needed in China to reduce the uncertainty in MIR calculations.

  AS04-D1-EVE-P-049 (AS04-A063)
Investigation on the Nonlinear Response of Air Pollution to Percursor Emissions Under Heavy Pollution Condition
Jia XING#+, Dian DING
Tsinghua University, China
#Corresponding author: +Presenter

Tropospheric ozone (O3) and fine particulate matter (PM2.5) are two major air pollutants that exert significant effects on human health and the global climate. Understanding of the relationship between the responses of O3 and PM2.5 to precursor emission changes is a prerequisite for making suitable policy decisions. Both O3 and PM2.5 exhibits strong nonlinear responsiveness to reduction in their precursor emissions, manifested as the volatile organic compound (VOC)-limited or NOx-limited O3 chemistry and NH3-rich or NH3-poor PM chemistry. This presents a difficult challenge for policy design. In this study, we investigated the responsive behavior of O3 and PM2.5 concentrations to precursor emissions, which are represented by a polynomial family of functions. The polynomial functions developed in this study will be applied in all grid cells across the simulated domain and all days across the simulated periods for both clean and polluted period. The response function will investigated under different pollution levels for both Oand PM2.5 in China.

  AS04-D1-EVE-P-050 (AS04-A065)
Characteristics of Carcinogenic Hazard Air Pollutants Emitted from Waste Energy Power Plants in South Korea
Yumi KIM#+
Korea Environment Institute, South Korea
#Corresponding author: +Presenter

In South Korea, the Solid Refuse Fuel (SRF) defined in Act on the Promotion of Saving and Recycling of Resources can be used as a fuel to expand recycling of resources. In the case of Biomass-Solid Refuse Fuel (BIO-SRF), which is one of the SRFs, it is classified as renewable energy in Act on the Promotion of the Development, Use and Diffusion of New and Renewable Energy. Large-scale power generation companies that have to consider Renewable Energy Portfolio Standards have started to plan a power plant that uses BIO-SRF to increase the ratio of renewable energy. However, there is growing concern over uncertainties in BIO-SRF emissions and the growing use of BIO-SRF in the absence of adequate management of hazard air pollutions (HAPs). In this study, we analyzed the current situation in major cities and industrial complexes for carcinogenic HAPs (e.g., benzene, benzo (a) pyrene, etc.). Also, we propose strategic locations and regulatory conditions of BIO-SRF power plant through concentration change according to power plant emission using diffusion model. The results of this study will provide a scientific basis for the impacts of carcinogenic HAPs in establishing the expansion policy of BIO-SRF generation facilities in East Asian countries.

  AS04-D1-EVE-P-051 (AS04-A066)
Chemical Composition and Sources to Rain Water in North-East India
Rajyalakshmi GARAGA, Shovan SAHU, Sri H. KOTA#+
Indian Institute of Technology Guwahati, India
#Corresponding author: +Presenter

Precipitation samples in north-east India which is one of the 200 eco regions in the world were collected for one year. pH of the samples varied between 4.6 and 5.9, with 60% of them indicating acid rain events. Major components analyzed in the forty-one samples were: TOC (total organic carbon), metals (Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, Zn) and ions (Ca2+, Na+, K+, Mg2+, F-, Cl-, NO3- and SO42-). Mean values of ionic species followed the order: SO42->NO3>Cl>F>Ca2+>K+>Na+>Mg2+. The contribution of NO3- and SO42- to rainwater acidity was 55 and 45%, respectively. The neutralising capacity of Ca2+, K+ and Mg2+ was negligible. Isotope analysis (𝛅18O and 𝛅D) along with back trajectories from Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model indicated that evaporation from oceans and inland water was source of rain water during monsoon and non-monsoon seasons, respectively. Concentrations of SO42-, NO3- and TOC was higher when the trajectories passed through inland compared to trajectories originating from ocean. Source apportionment using the US EPA’s Positive Matrix Factorization (PMF) model revealed six sources, i.e. soil dust, industries, vehicular emissions, secondary sources, fossil fuel combustion and sea salt.

  AS04-D1-EVE-P-052 (AS04-A068)
Study on Monitoring of Black Carbon Concentration in a Forest Environment
Tsung Ming TSAO#+, Chiang WEI, Ching-Peng CHENG
National Taiwan University, Taiwan
#Corresponding author: +Presenter

Black carbon (BC) emissions are the second strongest contribution to current global warming after carbon dioxide emissions. The objective of this study was to investigate the sources of air BC pollutants, to understand ratio of vehicle emissions and biomass burning, and to compare 24-hour change trend on weekdays and holidays in the Xitou Experimental Forest, Taiwan. Concentration levels of BC were investigated based on 7-wavelength Aethalometer (AE-33). The results showed that the average monthly BC mass concentration, biomass burning and vehicle emission concentration were 1707, 322 and 1385 ng/mrespectively in the spring season. The vehicle emission concentration (81%) is greater than biomass burning (19%), indicating that over 80% of BC is supplied by vehicle emissions. BC mass concentration showed the trend as follows: spring > autumn > summer; biomass burning concentration showed the trend as follows: summer > spring > autumn; vehicle emission concentration showed the trend as follows: spring > autumn > summer. The average concentrations of vehicle emissions were highest on the Saturday in spring (1669 ng/m3), followed by weekday (1353 ng/m3) and the Sunday (1287 ng/m3). BC pollution emitted by vehicle in spring is highest on Saturdays and must be paid special attention. According to the 24-hour change trend on weekdays and holidays, BC mass concentration rose sharply from 7 am on Sunday to a maximum of 1 a.m., and then began to drop rapidly to 6 p.m. The pattern of change in BC on Sundays is clearly different from that on weekdays and Saturdays, probably related to the large tourists into the Xitou forest on Sunday morning. In the future, it will continue to observe and analyze changes as a reference for future managers of Xitou Experimental Forest to assess the growth of tourists, the carrying capacity of tourism, and management.

  AS04-D1-EVE-P-053 (AS04-A069)
Seasonal Variation of Negative Air Ion Concentration in a Forest Environment
Ching-Peng CHENG#+, Tsung Ming TSAO, Chiang WEI
National Taiwan University, Taiwan
#Corresponding author: +Presenter

Negative air ions (NAIs) are small gas ions with fast moving speed, short life cycle, and negative charge. NAIs have the effects of human health and purifying air (i.e., PM2.5 aerosols). Studies regarding the changes in NAIs and the possible mechanism associated with these changes in different seasons are still limited. This study armed to investigate seasonal variation of NAIs and to compare relationship between NAIs and microenvironment (wind speed, humidity, and temperature) in a forest environment and nearby stream in the Xitou Experimental Forest, Taiwan. Negative ion instruments (COM-3600 Inc., Tokyo, Japan) were used in the Xitou experimental forest for monitoring NAIs concentration. The result showed that NAIs average concentration in spring, summer, autumn, and winter seasons were 2258, 1088, 18402, and 8563 number/cm3, respectively. NAIs average concentration in autumn was significantly higher than that in other seasons. The seasonal NAIs concentration from the highest to the lowest showed the trend as follows: autumn> winter> spring> summer. NAIs concentration was significantly negatively associated with temperature and humidity. However, the wind speed and flow in stream were not significantly associated with NAIs concentration. Moreover, seasonal variation of NAIs concentration in a forest environment showed that not only microenvironment factors but also plant characteristics, tree species, stand density, tree height, and canopy closure would lead to different NAIs concentrations. In the future, it will continue to observe and analyze the 24-hour changes as a reference for effects of purifying air and human health.

  AS04-D1-EVE-P-054 (AS04-A074)
Influences of Sea/Land Breeze on the Pollutant Transport Between the Coastal Urban and Inland Areas
Lien-En HUANG1+, Ya-Pang JHUANG1, Yu-Chieh CHEN1, Yu-Chen TSAI1, Charles C.K. CHOU2, Shih-Yu CHANG1#
1 Chung Shan Medical University, Taiwan, 2 Academia Sinica, Taiwan
#Corresponding author: +Presenter

Urban air pollution is a major concern for environmental degradation and human health. The International Global Atmospheric Chemistry Project (IGAC) not only focused the linkage between megacities air pollution and climate change, but also stressed the impact of air pollution on human health. Taichung, in central Taiwan, is a rapid industrial growth city with population over 2 millions in the past decade. In this study, two real-time stations of aerosol chemical composition were set up for simultaneously measuring the temporal and spatial variation of the water-soluble ionic compositions of PM10 in Chung Shan Medical University (Taichung urban station) and Chushan Senior High School (inland station) in December 2016 and July 2017.

The results show that the sea/land breeze was the prevailing wind during the period of the weak winter monsoon. In the daytime, the sea wind was blown from the coastal to inland through Taichung urban. The time of maximum sea wind showed a lag of 1~2 hours between the urban and inland areas. The peak value of Na+/PM10 was usually observed 1 hour after the time of maximum sea wind in both two sampling stations. Comparison of hourly gases and soluble ion species before and after the peak value of Na+/PM10 between the urban and inland stations, the average concentrations of O3 and SO2 in the inland area were higher than that in the urban area. After the peak value of Na+/PM10, the SOR (sulfuroxidation ratio) showed the decreasing trend in the urban station, however, the increasing trend in the inland station. It indicated that the sea wind is an important mechanism for pollutant transport. The accumulation of primary pollutants and formation of secondary air pollutants enhanced the air quality degradation in the inland area.

  AS04-D1-EVE-P-055 (AS04-A077)
Ambient PM2.5 Levels and Health Risks in Beijing, China
Xiaohong XU#+
University of Windsor, Canada
#Corresponding author: +Presenter

Beijing, the capital of China, has experienced high ambient fine particulate matter (PM2.5) levels in the past few years. The 2013-2017 average PM2.5 mass concentration was 77.3 µg/m3, much higher than the grade-two annual concentration of 35 μg/m3 in the Chinese National Ambient Air Quality Standard. PM2.5 concentrations were higher at night (19:00 to 3:00) than during the day (4:00 to 18:00). Among the four seasons, winter had higher PM2.5 levels (97.5 µg/m3), followed by fall (74.7 µg/m3) and spring (73.6 µg/m3), and lower in summer (60.4 µg/m3). The lifetime human health risk of exposure to ambient PM2.5 was estimated during 2013-2015. Risk assessment methods of US Environment Protection Agency (USEPA) were employed to the following PM2.5 components: six elements (Cr, Co, Ni, As, Cd, Pb) and 16 USEPA priority PAHs for carcinogenic risk, and 13 elements (Al, Ba, Cr, Mn, Ni, As, Cd, Pb, Co, V, P, Cl, Se) for non-carcinogenic risk expressed as hazard quotient (HQ). The lifetime cancer risk was 3.82E-4. This value is much higher than the USEPA’s threshold of 1.00E-04 for sufficiently large risks. Contributions of carcinogenic PM2.5 components to cancer risk are in the order of Cr (50%) > As (27%) > Co (14%) > total PAHs (4%) > Pb (3%) > Cd (1%) and Ni (1%).  Summer accounted for 31% of total lifetime cancer risk, followed by winter (27%), spring (22%), and fall (20%). The estimated lifetime non-cancer HQ due to exposure to ambient PM2.5 was 16. According to USEPA, HQs greater than 1.0 indicate that some non-cancer effects may occur. Winter had the largest contribution of 52%, followed by spring (21%), fall (18%), and summer (9%). Overall, lifetime cancer and non-cancer risks in Beijing were much higher than the corresponding USEPA thresholds.

  AS04-D1-EVE-P-056 (AS04-A002)
On the Origin of Surface Ozone Episode in Shanghai over Yangtze River Delta During a Prolonged Heat Wave
Huansheng CHEN1#+, Jianbin WU1, Oliver WILD2
1 Chinese Academy of Sciences, China, 2 Lancaster University, United Kingdom
#Corresponding author: +Presenter

A heat wave with temperatures over 35°C and sunny stagnant meteorological conditions occurred in Shanghai from 27 July to 5 August 2015, leading to a sustained episode of high ozone lasting 12 days. We have conducted a detailed source apportionment of surface ozone, by precursor source category and region, using a photochemical transport model. In this episode, a southwesterly wind prevailed over the Yangtze River Delta, and therefore precursors from the local Shanghai region and the region immediately to the south of Shanghai are the two major contributors (in total 90%) to ozone in Shanghai. The source apportionment reveals that local industrial sources and energy/biogenic sources in neighbouring regions are the principal causes for the high levels of ozone. By examining the contributions from individual physical and chemical processes, we show that ozone concentrations start to rise rapidly in the morning because chemical production dominates as the solar radiation increases, and while there is little removal by deposition when ozone remains low. In general, chemical production, horizontal advection and vertical diffusion contribute to increase ozone concentration during daytime, and deposition and vertical advection reduce ozone concentrations.