AOGS 2018 - Browse Abstracts

Browse by Session - Select Session:
 
Oral Presentations - Browse by Section and Presentation Day
  Section:
Poster Presentations - Browse by Section
  Section:
Input Keyword
Abstract Title Word
 

 

Poster Presentations of Section BG

Print this page

  (BG07-A009)
 
Terrestrial Biogeochemistry of Hg at a Wood Preservation Site
Flora BROCZA1#+, Harald BIESTER2, Bhoopesh MISHRA3, Jan-Helge RICHARD4, Stephan KRAEMER1, Jan WIEDERHOLD1
1 University of Vienna, Austria, 2 Technical University of Braunschweig, Germany, 3 University of Leeds, United Kingdom, 4 Institute for Hygiene and Environment, Germany
#Corresponding author: flora.brocza@gmail.com +Presenter

Mercury (Hg) is a dangerous global pollutant - its toxicity and mobility strongly depend on its speciation, requiring one to look beyond mere concentrations to perform risk assessments at Hg-contaminated sites. To understand speciation processes at a former wood preservation site in SW-Germany, where aqueous HgClhad entered the soil, we used an integrated set of techniques.

Firstly, Hg concentrations and speciation were analyzed in two soil cores. Hg speciation was assessed qualitatively using sequential extractions (SE) and pyrolytic thermo-desorption (PTD). Selected samples were then analyzed quantitatively using synchrotron-based X-ray Absorption Spectroscopy (XANES, EXAFS). Secondly, to identify species transformation processes, Hg stable isotope analysis (CV-MC-ICP-MS) was conducted on the samples’ SE pools and total digests. Changes in Hg stable isotope signatures during species transformations have been reported in laboratory studies to be representative of different transformation processes.

Maximum concentrations of 802 µg g-1 Hg were found at 2.5 m depth. The speciation of all measured samples was distinctly different from the original HgClcontamination source. Samples contained at least 34% and up to 91% of highly stable Hg phases according to SE, confirmed as β-HgS by XANES. XANES also revealed significant amounts of reduced Hg(0) in the most contaminated samples, in agreement with the PTD results. Surprisingly, XANES revealed the presence of a Hg(I) phase, likely calomel (Hg2Cl2). Hg isotope ratios measured using CV-MC-ICP-MS exhibited resolvable variations between the extracted pools. Bulk samples showed δ202HgNIST-3133 values as low as ‑0.43‰ (±0.09‰, 2SD), similar to average literature values of industrial Hg. Water extracts were enriched in heavy isotopes (up to +0.18‰) similar to nearby groundwater. Despite oxidizing conditions in the soil, significant formation of Hg(0) and Hg(I)has altered the Hg pools’ isotopic signatures, painting a complex picture of soil Hg transformations, and influencing the mobility of Hg towards the groundwater.

  BG01-D3-PM1-P-011 (BG01-A004)
 
Diversity of Nitrogen Fixing Bacterial Communities in the Coastal Sediments of South Eastern Arabian Sea (SEAS)
Mohamed Hatha A. A.#, Jabir THAJUDEEN+, Vipindas T. V., Jesmi YOUSUF
Cochin University of Science and Technology, India
#Corresponding author: mohamedhatha@gmail.com +Presenter

The potential role and diversity of nitrogen (N2) fixing bacterial communities in the coastal sediments of the South Eastern  Arabian Sea (SEAS) have been revealed in this study. The N2 fixing bacterial communities were determined by clone library analysis of nifH gene. The results of the study indicated that over 15 putative diazotrophs belongs to phyla alpha-, beta-, gamma-, delta-, epsilon- proteobacteria and firmicutes were observed in the coastal sediments of SEAS. The predominant genera observed among these were Dechloromonas sp. (beta-proteobacteria); Azotobacter sp., Methylobacter sp., and Rheinheimera sp. (gamma-proteobacteria); Desulfobacter sp. and Desulfovibrio sp. (delta-proteobacteria); Sulfurospirillum sp. (epsilon-proteobacteria). Among these, Desulfobulbus lactus, and Desulfovibrio desulfuricans are the major N2 fixing sulphate reducing bacterial phylotypes. The observed N2fixation rate in the SEAS varied from 0.12 to 0.36 nmol N g-1 h-1. Shannon-Weiner diversity index of N2 fixing bacteria were ranged from 3.5 to 3.72 and it indicates the prevalence of broad diversity of N2 fixing bacteria. Canonical correspondence analysis (CCA) revealed significant influence of the environmental variables such as sediment type, total nitrogen (TN), total organic matter (TOM), total organic carbon (TOC), iron (Fe), manganese (Mn), total sulphur (TS), nitrite  (NO2-) and nitrite (NO3-) contents of the sediment on N2 fixation rate and diversity of N2 fixing bacteria in  the SEAS. The observations of the current study provide a better understanding of the N cycling in coastal sediments of the SEAS and sources of fixed N2.

  BG01-D3-PM1-P-012 (BG01-A005)
 
The Flux Estimation of Dissolved Organic Carbon from Subtropical Small Mountainous Rivers During Typhoon and Non-Typhoon Periods in Taiwan
Tsung-Yu LEE1#+, Li-Chin LEE2, Jr-Chuan HUANG2
1 National Taiwan Normal University, Taiwan, 2 National Taiwan University, Taiwan
#Corresponding author: tylee@ntnu.edu.tw +Presenter

Small mountainous rivers are hotspots of global land-to-ocean organic carbon export. However, relatively few studies have focused on dissolved organic carbon (DOC) compared to particulate organic carbon. In a long-term project (2002 to 2014), stream DOC was monitored in three neighboring subtropical small mountainous rivers of Taiwan. The objective was to relate DOC concentrations to water discharge and to quantify DOC flux during typhoon and non-typhoon periods. Seasonal fluctuations of DOC concentrations were closely correlated with air temperature at all sampling stations. During non-typhoon periods, increasing water discharge led to decreasing DOC concentrations due to a dilution effect. However, during typhoon periods, DOC concentrations increased with some lead time along the hydrograph and reached the annual maximum which likely sources from a significant input of litter and upper soil layers. The mean DOC concentration of the studied systems (<1.0 mg L-1), is ranked in the lowest 1% among the world rivers. However, mean DOC yield (~30 kg ha-1 y-1), is ranked in the top 30%, which is attributed to high rainfall and substantial organic carbon stocks in the watersheds. Up to 25±5.6% of the annual DOC flux was contributed by typhoon events, which occupied ~3% of the monitoring period. We conclude that typhoon events are important drivers for the land-to-ocean export of dissolved organic matter. Predicted future increases in frequency and magnitude of typhoon events will likely accelerate the release of terrestrial carbon and enhance its land-to-ocean transfer via dissolved organic matter.

  BG01-D3-PM1-P-013 (BG01-A006)
 
Intercomparison of Two Cavity Ring-Down Spectroscopy Analyzers for Atmospheric 13CO2/12CO2 Measurement
Jiaping PANG#+
Chinese Academy of Sciences, China
#Corresponding author: pangjp@niglas.ac.cn +Presenter

Isotope ratio infrared spectroscopy (IRIS) permits continuous in situ measurement of CO2 isotopic composition under ambient conditions. Previous studies have mainly focused on single IRIS instrument performance; few studies have considered the comparability among different IRIS instruments. In this study, we carried out laboratory and ambient measurements using two Picarro CO2δ13C analyzers (G1101-i and G2201-i (newer version)) and evaluated their performance and comparability. The best precision was 0.08–0.15‰ for G1101-i and 0.01–0.04‰ for G2201-i. The dependence of δ13C on CO2 concentration was 0.46‰ per 100 ppm and 0.09‰ per 100 ppm, the instrument drift ranged from 0.92–1.09‰ and 0.19–0.37 ‰, and the sensitivity of δ13C to the water vapor mixing ratio was 1.01‰/% H2O and 0.09‰/% H2O for G1101-i and G2201-i, respectively. The accuracy after correction by the two-point mixing ratio gain and offset calibration method ranged from -0.04–0.09‰for G1101-i and -0.13–0.03‰ for G2201-i. The sensitivity of δ13C to the water vapor mixing ratio improved from 1.01‰/% H2O before the upgrade of G1101-i (G1101-i-original) to 0.15‰/% H2O after the upgrade of G1101-i (G1101-i-upgraded). Atmospheric δ13C measured by G1101-i and G2201-i captured the rapid changes in atmospheric δ13C signals on hourly to diurnal cycle scales, with a difference of 0.070.24‰ between G1101-i-original and G2201-i and 0.050.30‰ between G1101-i-upgraded and G2201-i. A significant linear correlation was observed between the δ13C difference of G1101- i-original and G2201-i and the water vapor concentration, but there was no significant correlation between the δ13C difference of G1101-i-upgraded and G2201-i and the water vapor concentration. The difference in the Keeling intercept values decreased from 1.24‰ between G1101-i-original and G2201-i to 0.36‰between G1101-i-upgraded and G2201-i, which indicates the importance of consistency among different IRIS instruments.

  BG01-D3-PM1-P-014 (BG01-A008)
 
Patterns and Environmental Controls of Soil Organic Carbon and Total Nitrogen in Alpine Ecosystems of Northwestern China
Longfei CHEN#+
Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, China
#Corresponding author: chenlongfei_mail@163.com +Presenter

Soil carbon (C) and nitrogen (N) in alpine ecosystems are of special interest because of high concentration and potential feedbacks to climate changes. Alpine ecosystems of the Qilian Mountains in the northern margin of the Tibetan Plateau are characterized by complex topography, suggesting large variability in the spatial distribution of soil C and N. However, the patterns and environmental controls on C and N storage are not well understood.This study was conducted todetermine the soil organic carbon (SOC) and total nitrogen (TN) stocks under different vegetation types and environmental conditions in a typical catchment in the Qilian Mountains, and explore their environmental control factors. The results showed that SOC and TN stocks varied significantly with vegetation type, ranging from 9.50 to 31.09 and 1.07 to 3.14 kg m-2, respectively, at 0-50 cm soil depth. SOC storage in grasslands on sunny slopes and in Picea crassifolia forest together accounted for about 80% of the total SOC storage in the catchment due to the extensive distribution area of these vegetation types. SOC stocks in grasslands on sunny slopes and in P. crassifolia forest were generally higher than their counterparts in other regions. SOC stocks on shady slopes were mainly regulated by elevation-induced differences in temperature and precipitation, with temperature being the most important factor influencing the distribution of SOC. For the whole catchment, the distribution of SOC stocks was significantly affected by topographic aspect and elevation; aspect and elevation together explained 97.5% of the overall variation in SOC stocks at a soil depth of 0–50 cm, and aspect alone explained 68.2% of the overall variation. These results confirmed that topography was the most significant factor controlling the distribution patterns of SOC in alpine ecosystems.

  BG01-D3-PM1-P-015 (BG01-A011)
 
Agricultural Nitrogen Emissions in Response to Historical Shifts (1980s-2010s) of Fertilizer Application in the Taihu Lake Basin
Hengpeng LI1#+, Yaqin DIAO2, Guishan YANG2
1 Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, China, 2 Chinese Academy of Sciences, China
#Corresponding author: lihp.cas@outlook.com +Presenter

Irrational uses of fertilizers have been demonstrated as among the most important reasons for widespread eutrophication and algal bloom. Understanding historical nitrogen (N) emissions will enhance our understanding of the reasons behind increasing concerns of water pollution. In this study, we present the analysis in the Taihu Lake Basin, which has been considered as one of the heavily polluted basins with rapid shifts in the sources and quantities of fertilizer application. During the period of 1980s to 2010s, fertilizer application had increased from 350 kg•ha-1•yr-1 to 550 kg•ha-1•yr-1, but the proportion of manure had reduced from 30% to 0. With an aim to reconstruct historical N loads in response to rapid shifts in fertilizer application, we adopted DNDC model to perform the analysis. Our results indicate that N leakages followed the similar trend of fertilizer application, both of which have increased first and then decreased during the period studied. While, N loss via runoff showed continually increased from 6.34±1.89 kg·N ha-1·yr-1to 28.14±5.71 kg·N ha-1·yr-1. The durations with the highest risk of runoff loss and leakage have extended from one month (July) to three months (June-August), and three months (January-March) to five months (December-April), respectively. On seasonal basis, about 55-73% of N loss via runoff were concentrated in the rainy season (June-August), while 45-55% of N loss via leakage were tended to be occurred in the winter (January-March). The study has gone some way towards enhancing our understanding of the historical dynamics of N pollution of the Taihu Lake, and also has provided insights for agricultural N management. Future mitigation strategies will need to be concentrated on gradually optimizing the fertilization, as our results indicated that current agricultural system have already generated intensive surplus N.

  BG01-D3-PM1-P-016 (BG01-A018)
 
Kinetics of Coenzyme F430 Degradation for Application as a Biomarker of Methane Production and Consumption
Masanori KANEKO#+
National Institute of Advanced Industrial Science and Technology, Japan
#Corresponding author: m-kaneko@aist.go.jp +Presenter

Coenzyme F430 is a hydrocorphinoid nickel complex, which is a prosthetic group of methyl coenzyme M reductase (MCR). Coenzyme F430 can be a robust biomarker to clarify biological methane cycle since it is a function specific compound for methanogenesis and anaerobic methane oxidizing archaea (reversed methanogenesis).

Native structure of coenzyme F430 is unstable after release from MCR and readily modified in a laboratory condition. Hence, it is assumed that coenzyme F430 will not accumulate in geological samples and its distribution reflects modern methane production and consumption processes. However, quantitative degradation rate of F430 have not been studied.

In this study, degradation experiments of F430 was performed at various pH and temperature condition to clarify kinetics of epimerization of F430 which is an initial and important step of abiotic F430 degradation.

Coenzyme F430 was converted to 12, 13-diepi-F430 via 13-epi-F430 during epimerization. The concentration of coenzyme F430 was exponentially decreased, which indicates pseudo-first order reaction. Determined rate constant (k) based on the curve fitting ranged from 4.5 x 10-4 to 0.062 at a range of experiment temperature 15-60°C and pH7, hence half-lives range from 234 to 0.5 days. Arrhenius plot shows strong correlation between k and temperature. Predicted half-life at 2°C which is simulated condition of sediment-seawater interface is 304 days.

Our results demonstrated that coenzyme F430 readily convert to its epimers and will not accumulate in even in low temperature environments such as near-surface marine sediments.

  BG01-D3-PM1-P-017 (BG01-A019)
 
The Impacts of Nitrogen Dynamics on Plant Growth and Carbon and Water Balances: An Investigation Using Noah-MP-CN
Jingjing LIANG1#+, Zong-Liang YANG2
1 Chinese Academy of Sciences, China, 2 The University of Texas at Austin, United States
#Corresponding author: liangjing@tea.ac.cn +Presenter

Nitrogen cycle is critical to the development of terrestrial land surface models (LSMs), as it affects plant growth, the carbon and water cycles. In this study, we use the community Noah LSM with multi-parameterization options (Noah-MP), the next-generation LSM for the Weather Research and Forecasting (WRF) meteorological model, coupled to the Fixation and Uptake of Nitrogen (FUN) plant model and the Soil and Water Assessment Tool (SWAT) model to represent nitrogen dynamics. The coupled model (hereafter Noah-MP-CN) is evaluated at the regional scale using China as a testbed. The reference datasets include the Leaf Area Index (LAI) obtained from Beijing Normal University GLASS dataset, net primary productivity (NPP), gross primary productivity (GPP), and evapotranspiration (ET) from MODIS, and soil moisture from the ERA-interim reanalysis. Our results show that Noah-MP-CN exhibits better simulation of LAI, NPP and GPP in comparison with Noah-MP with lower values of root-mean-square error (RMSE) and greater values of correlation coefficient (R), especially in cropland regions. For the water cycle variables, Noah-MP-CN shows some improvement in soil moisture simulations but relatively worse ET simulations. These results represent the first Noah-MP-CN simulation and evaluation at the regional scale. It also demonstrates that Noah-MP-CN can be potentially used in future environmental prediction applications, such as the water quality predictions.

  BG01-D3-PM1-P-018 (BG01-A023)
 
Methane and Nitrous Oxide Emissions from Ratoon Rice Fields
Jing MA#+, Kaifu SONG, Haiyang YU, Guangbin ZHANG, Hua XU
Chinese Academy of Sciences, China
#Corresponding author: jma@issas.ac.cn +Presenter

Ratoon rice is a cultivation technology, which use rice regeneration ability and special cultivation methods to get harvest one more time than the single rice, and play an important role for raising food yield and farmer’s income. To elucidate the seasonal variations of CH4 and N2O emissions from ratoon rice fields, a field experiment was conducted in Ziyang, Sichuan Province, China in 2017. Five rice varieties (Single rice: Chuanxiang 8108; Ratoon rice: Taiyou 390JingliangyouhuazhanYuxiang 203Fengliangyouxiang 1) were adopted in the experiment. Results showed that the seasonal peak of CH4 flux of ratoon rice appeared at early of May, about half of month earlier than that of single rice. The total CH4 emissions of ratoon rice ranged from 106 to 143 kg/ha, being highest in Yuxiang 203 and lowest in Taiyou 390, of which CH4 emissions during ratooning period contributed 18-29%. Compared with single rice, ratoon rice decreased CH4 emission by 2-18% except Yuxiang 203. Different to single rice, substantial N2O emissions from ratoon rice were observed not only during the midseason aeration but also after fertilizer application for bud development. The total N2O emissions of ratoon rice ranged from 2.89 to 6.61 kg N/ha, being highest in Jingliangyouhuazhan and lowest in Fengliangyouxiang 1, of which N2O emissions during ratooning period contributed 7-41%. Compared with single rice, N2O emissions from ratoon rice were 0.4-2.1 times higher. The total grain yields of ratoon rice ranged from 10.03-11.50 t/ha, being highest inJingliangyouhuazhan, lowest in Taiyou 390,and 22-40% higher than single rice. By integrating CH4 and N2O emissions and grain yield, Taiyou 390 and Fengliangyouxiang 1 were 3-5% and 22-29% lower than single rice in GWP (global warming potential) and GHGI (greenhouse gas intensity), respectively. Based on these results, Taiyou 390 and Fengliangyouxiang 1 were recommended, as these two varieties increased rice grain yield with no increase in GWP.

  BG02-IG-D3-PM1-P-012 (BG02-IG-A004)
 
Habitat Suitability Empirical Model of Albacore Tuna in the North Pacific Ocean Using Multi-Satellite Remote Sensing Data
Ming-An LEE#+
National Taiwan Ocean University, Taiwan
#Corresponding author: malee@mail.ntou.edu.tw +Presenter

Albacore tuna (Thunnus alalunga) is one of the important commercial species of the longline fishery in the North Pacific Ocean (NPO). The satellite-derived environmental variables, including sea surface temperature (SST), sea surface height anomaly (SSHA), mixed layer depth (MLD), sea surface chlorophyll-a (SSC), and eddy kinetic energy (EKE), were used to combine with the nominal catch per unit effort (CPUE) data of Albacore (Thunnus alalunga) from Taiwanese longline fisheries during 1998~2014 for establishing the empirical habitat suitability index (HSI) in the NPO. Our results revealed that the high nominal CPUE occurred in November to March in time and distributed over 25~40°N in space. The marine environment of  albacore habitat in SST, SSHA, MLD, SSC, and EKE, respectively, are ranged about 19~22.5°C, 0.3~0.55m, 40~150m, 0.08~ 0.14mg/m3, and 0.025~0.15 cm/s2. The geographic information system maps of the predicted HSI values overlapped by the observed nominal CPUE, suggesting that the maximum entropy model can be used as a reliable tool for prediction of potential fishing grounds in the NPO.

  BG02-IG-D3-PM1-P-013 (BG02-IG-A005)
 
Modelling of Winter Potential Fishing Zones for Grey Mullet (Mugil Cephalus L.) Based on IPCC Climate Scenarios in the Northwestern Pacific
Ming-An LEE#+
National Taiwan Ocean University, Taiwan
#Corresponding author: malee@mail.ntou.edu.tw +Presenter

Grey mullet is one of the most important commercial species of fish in the coastal fisheries of Taiwan. Since 2000 their fishing grounds are to the north following changes in the 20 °C isotherm in the Taiwan Strait (TS). In this study, the GCM model for Sea surface temperature (SST), salinity, sea surface high, chlorophyll-a, mixed layer depth (MLD), current velocity of IPCC AR5 four scenarios (RCP2.6, RCP4.5, RCP6.0 and RCP8.5) and topographic data of fishing ground were used to combine with mullet catch data of gillnet during 2015~2017 for establishing the empirical habitat suitability index of grey mullet in the North Pacific Ocean. Our results revealed that current velocity was the most important environmental variables influencing the fishing ground of grey mullet, while the remaining variables include Salinity, MLD and SST. In addition, the potential fishing zones is mainly distributed in the waters around Chang-Yun Rise, TS. And their potential fishing zones may subsequently and northwardly shift to the coastal waters of northwestern Taiwan in 2035, and then extendedly to the coastal waters of north Taiwan in 2050.

  BG02-IG-D3-PM1-P-014 (BG02-IG-A009)
 
A Simple Method for Correcting the Blooming Effect in DMSP-OLS Images
Xin CAO#+, Yang HU, Xuehong CHEN, Jin CHEN, Fang FANG
Beijing Normal University, China
#Corresponding author: caoxin@bnu.edu.cn +Presenter

Nighttime light (NTL) data, such as DMSP-OLS and Suomi NPP-VIIRS images, provide a unique observation on nocturnal human activities, and have been associated with urbanization, economic development, population density, energy consumption, light pollution, air quality and CO2 emission. DMSP-OLS data provides the longest observation of NTL information from 1992 to 2013; however, it is suffered from problems such as coarse spatial resolution, lack of onboard calibration, saturation and blooming. 

The blooming effect, or overglow, refers to the lighted areas detected by the OLS larger than the geographic extents of the light sources. The possible reasons for blooming include the relatively coarse spatial resolution of the OLS sensor, the detection of diffuse and scattered light over areas containing no light source, and the accumulation of geolocation errors in the compositing process. Existing studies also found that blooming effect is related to lighted areas, light source strength, adjacent water bodies or snow, and thin cloud. Blooming effect will lead to overestimate the extent of urban area extraction, and cannot allow a fixed threshold for urban extraction by OLS data. However, only a few researches quantitatively evaluates the blooming effect, and researchers have no consensus on blooming effect correction. 

This research proposed a simple method for correcting blooming effect, by supposing edge pixels in OLS images are completely scattering from neighboring higher light intensity pixels. Scale-based models are built up according to light levels, and then the light from outliers are recruited to interior pixels. This model is independent to ancillary data such as NDVI, LST or statistics. The recovered OLS data can eliminate blooming effect, and enable a fixed threshold for urban area extraction. The blooming effect correction is suggested as an effective pre-processing procedure anterior to relative calibration and saturation correction. 

  BG02-IG-D3-PM1-P-015 (BG02-IG-A012)
 
New Insights into the Role of Below-Ground Competition in Above-Ground Self-Thinning Pattern of Shrub
Xihong CUI#+, Xin CAO, Jin CHEN, Xuehong CHEN
Beijing Normal University, China
#Corresponding author: cuixihong@bnu.edu.cn +Presenter

Plant self-thinning power law is regarded as an essential regulation which plays an important role in determining population dynamics and community structure. However, little experimental and theoretical studies on the power law have been developed for shrub, and also little has been done from the perspective of below-ground plant parts to reveal the mechanisms underlying the self-thinning process of natural plant especially in field. Ground-penetrating radar (GPR) has provided a non-invasive method for studying plant root system in situ. However, previous studies are focused on measuring certain root sample under controlled experimental conditions, or detecting root distribution of individual plant. Little has been done on the plant community scale to survey root distribution and estimate root biomass under natural conditions. Taking the shrub, Caragana microphylla, as example, this study revealed the belowground root mass-density relationship and the root spatial distribution of Caragana microphylla quadart. The below-ground root distribution are surveyed by Ground- penetrating radar (GPR). The number of root points recognized from radagrams is used as root mass to build relationship with the up-ground population density of Caragana microphylla. We found that the below-ground root mass-density relationship of Caragana microphylla is more robust than those of above-ground parts, and the root distribution shows a trend to reach a “closed canopy” in below-ground space, in spite of its above-ground canopy coverage is very low. These results provides further evidence that below-ground root competition is an important factor governing above-ground population density in water-limited environments and can partly explaine how does the root competition work in the self-thinning process shrub. This study maybe serve as a frame of reference for future studies in root competition of natural plants.

  BG02-IG-D3-PM1-P-016 (BG02-IG-A021)
 
On Operational Monitoring of Water Quality Parameters by Satellite Remote Sensing in a Turbid Inland Lake of Japan
Wei YANG1#+, Bunkei MATSUSHITA2, Akihiko KONDOH1
1 Chiba University, Japan, 2 University of Tsukuba, Japan
#Corresponding author: yangwei@chiba-u.jp +Presenter

Eutrophication occurring in global inland lakes becomes a serious environmental issue in recent decades. Sustainable management of freshwater ecosystems requires routine monitoring of water quality parameters. Unfortunately, the spatial and temporal heterogeneity of water areas often results in inadequate monitoring and analysis of water quality using conventional in-situ sampling methods. Satellite remote sensing is a feasible technique for monitoring inland lakes in terms of being able to cover large spatial areas at very frequent intervals. In this study, ENVISAT/MERIS satellite images were applied to estimate the chlorophyll-a concentration, Secchi disk depth, and primary production in Lake Kasumigaura, Japan between 2003 and 2012. The MERIS Level 1B radiance data were first processed through an atmospheric correction algorithm developed specifically for turbid inland waters. Then the water quality parameters were retrieved from the atmospherically corrected reflectance using a series of our algorithms developed in previous studies. Finally, the satellite-derived parameters were compared with the field database of Lake Kasumigaura. The results showed that the MERIS data in tandem with the atmospheric correction and water quality retrieval algorithms yielded acceptable accuracies with a normalized mean absolute error (NMAE) lower than 34%, and a coefficient of determination (R2) higher than 0.73. Moreover, the MERIS-derived parameters also showed seasonal and yearly variations similar to those of the field measured data. These findings demonstrate the potential of our proposed algorithms to routinely monitor water quality in Lake Kasumigaura using satellite observations in an operational manner.

Key words: inland lake, satellite remote sensing, operational monitoring, water quality

  BG02-IG-D3-PM1-P-017 (BG02-IG-A022)
 
Spatial Differences of Long-Term Changes of Chlorophyll-A and Red Tide Events in the Taiwan Strait in Spring
Caiyun ZHANG#+
Xiamen University, China
#Corresponding author: cyzhang@xmu.edu.cn +Presenter

The Taiwan Strait (TWS) is an important channel linking the East China Sea and the South China Sea. Its hydrodynamic environment is dominated by the East Asian monsoon. Spring is in the transition season of the winter northeastern monsoon and the summer southwestern monsoon. Although the influence of cold, fresh and eutrophic Zhe-Min coastal water (ZMCW) gradually weaken in spring, it has brought abundant nutrients to the TWS. Therefore, the bloom events frequently occur in the TWS in spring. Spring is also a season with high red tide occurrence. Based on the long-term series of multi-source remote sensing data and red tide observation data, we have found that there was a significant spatial difference in the long-term changes of chlorophyll a and red tide events in the Taiwan Strait during 2003-2016. The chlorophyll a concentrations and red tide occurrence significantly increased in the central TWS, while the northern TWS is opposite. We examined the impacts of the factors such as the intensity and extent of ZMCW, thermal front, wind mixing, runoff, irradiance and SST, on the long-term changes of Chla and red tide events. The analysis showed that the influence of ZMCW has become stronger and the front intensity increased in the central and southern TWS, which might lead to increase chlorophyll concentration. However, the SST was too low in the northern TWS, meanwhile the front intensity weakened, which might in turn inhibits phytoplankton growth. As for the other factors, there are no significant spatial differences among them. Overall, the changes of TWS ecosystem in spring are quite complex, further studies require the joint efforts of multidisciplinary field observation and modeling.

  BG02-IG-D3-PM1-P-018 (BG02-IG-A025)
 
Spatio-Temporal Characteristics of NO2 in Africa and Typical Urban Agglomerations Under the Anthropogenic Influences Analysis Based on OMI Data
Qun GAO#+
Chinese Academy of Sciences, China
#Corresponding author: qgao@niglas.ac.cn +Presenter

Nitrogen dioxide (NO2) is one of the most important pollutants of human emissions. Real-time monitoring of its temporal and spatial distribution and content is of great significance for air quality research. The monthly tropospheric NO2 data over Africa acquired from the Ozone Monitoring Instrument (OMI) was analyzed with respect to spatial distribution and long-term trends between 2005 and 2016. Combined with the African land use data, night light data, and the human footprint data, the difference and influence of human multi-dimensional changes on tropospheric NO2 were analyzed. The results showed that Africa the average tropospheric NO2 column concentration was 1.925*1015molec/cm2, far below the global average level of other continents, but the concentration of TropNO2 increased significantly over the past 12 years with an average annual growth rate of 1.03%. In the higher urbanization areas, such as Mega City Cairo and Johannesburg metropolitan area, the value of TropNO2 was higher than any other areas. Nearby 10°N and 10°S latitude regions, there were two high value areas. Concentration of TropNO2 in Central Africa was higher followed by South Africa, East Africa, West Africa and North Africa. The temporal trend of TropNOwas the concentration of dry season was higher than the rainy season. The temporal and spatial distribution characteristics of African TropNO2 concentration was affected by both natural factors and human activities. In the urbanization areas, human activities and economic development are the main causes and in the forest and savanna areas, wildfire was one of the main sources of atmospheric NO2. The concentrations of NO2 column in different land use types were different. The concentration of NO2column above urban land were relatively higher and also showed a trend of increasing during the research period.

  BG03-IG-D3-PM1-P-008 (BG03-IG-A004)
 
Adjoint Analysis on High CH4 Mole Fractions Observed by Aircraft
Yosuke NIWA1#+, T. MACHIDA1, Yousuke SAWA2, Taku UMEZAWA1, Kazuhiro TSUBOI2, Kazuyuki SAITO2, Hidekazu MATSUEDA2, Nobuko SAIGUSA1
1 National Institute for Environmental Studies, Japan, 2 Japan Meteorological Agency, Japan
#Corresponding author: niwa.yosuke@nies.go.jp +Presenter

Asia is one of important source regions of methane (CH4), which is released mainly from industrial and biogenic processes. Biogenic emissions in Asia are strongly coupled with the Asian monsoon. During the summer monsoon, increased biogenic CH4 emission signals are effectively uplifted to the free-troposphere by the monsoon-induced convective air flows over the continent. Consequently, CH4 mole fractions over the western North Pacific, i.e. the downwind region of the continent, are often elevated even when the sink by OH radical is maximized. This phenomenon has been well observed by aircraft observations under the CONTRAIL project, which uses commercial airliners connecting Japan and Australia/Bangkok, and under the operational observation program of Japan Meteorological Agency, which uses the C-130H aircraft connecting the Japan main island and Minamitorishima. In this study, we use forward and adjoint modes of the atmospheric transport model NICAM-TM to show highly resolved contributions of the Asian sources to such high CH4 events observed by those aircraft and investigate the detailed transport pathway of the high CH4 air masses.

  BG03-IG-D3-PM1-P-009 (BG03-IG-A006)
 
Carbon Dioxide (CO2) Flux Seasonality and Monsoon in the Indian Subcontinent
Prabir PATRA1,2#+, Pramit DEB BURMAN3, Chandra Shekhar JHA4, Supriyo CHAKRABORTY3, Dipankar SARMA5, Kireet KUMAR6, Sandipan MUKHERJEE6
1 Japan Agency for Marine-Earth Science and Technology, Japan, 2 Tohoku University, Japan, 3 Indian Institute of Tropical Meteorology, India, 4 Indian Space Research Organisation, India, 5 Tezpur University, India, 6 G.B. Pant National Institute of Himalayan Environment and Sustainable Development, India
#Corresponding author: prabir@jamstec.go.jp +Presenter

The South Asian monsoon system in the summer predominantly controls the supply of water to the natural ecosystem and agricultural activity in the India subcontinent (consisting of India, Pakistan, Bangladesh, Nepal, Bhutan and Sri Lanka). Inverse modelling of atmospheric CO2 concentration using transport modelling suggested that maximum carbon uptake over the Indian subcontinent occurs in the months of July-August following the onset of the South Asian monsoon. Studies also show the lack of our understanding in modeling the terrestrial ecosystem activity as the ecosystem models fail to simulate the CO2 flux seasonal cycle consistently (Patra et al., 2013). They suggested a peak in CO2 uptake in the month of Jun-Aug by inverse modelling (Patra et al., 2011), while the majority of the ecosystem models predicted peak uptake later in the Autumn. Recently, the flux tower network has grown significantly in India for precisely estimating the CO2 fluxes between the atmosphere and land ecosystems and subsequent refinements of the models. A recent study (Deb Burman et al., 2017) clearly showed that the observed leaf area index (LAI) is peaking around June and remain high through August of 2016 at a semi-evergreen moist deciduous forest named Kaziranga National Park, India. This is in contrast with remote sensing measurements by MODIS, which sees LAI peak sharply in Sep-Oct. They calculate maximum GPP in Jun-Jul. Another observation site at Betul also showed similar results as those observed at Kaziranga (Jha et al., NRSC). Observations from Katarmal, a Pine mixed forest of central Himalaya showed peak of GPP in Jun-Jul for 2014-2016 (Kumar and Joshi 2010).

With this presentation we call for more research groups to participate by contributing flux tower observations, inverse modelling results and ecosystem model simulation for better understanding of the processes controlling carbon exchange in the South Asian ecosystems.

  BG04-D3-PM1-P-018 (BG04-A006)
 
Implications of Overestimated Anthropogenic CO2 Emissions on East Asian and Global Land CO2 Flux Inversions
Tazu SAEKI1#+, Prabir PATRA2,3
1 National Institute for Environmental Studies, Japan, 2 Japan Agency for Marine-Earth Science and Technology, Japan, 3 Tohoku University, Japan
#Corresponding author: Saeki.tazu@nies.go.jp +Presenter

Measurement and modeling of regional or country-level carbon dioxide (CO2) fluxes are critical for verification of the greenhouse gases emission control. One of the commonly adopted approaches is inverse modeling, where CO2 fluxes from the terrestrial ecosystems are estimated by combining atmospheric CO2measurements with atmospheric transport models. The inverse models assume anthropogenic emissions are known, and thus an uncertainty in the emissions would introduce systematic bias in estimated terrestrial (residual) fluxes by inverse modeling. Here we show that the CO2 sink increase, estimated by inverse modelings, over East Asia (China, Japan, Korea and Mongolia) is likely an artifact of the a priori anthropogenic CO2 emissions. The residual CO2 sink increase by about 0.26 PgC yr-1 (1 Pg = 1015 g) during 2001-2010 is calculated as the fossil fuel (anthropogenic) emissions increased too quickly in China by 1.41 PgC yr-1. Independent results from methane (CH4) inversion suggested about 41% lower rate of East Asian CH4 emission increase during 2002-2012. We thus apply a scaling factor of 0.59, based on CH4 inversion, to the rate of anthropogenic CO2 emission increase. By doing that we find no systematic increase in land CO2 uptake over East Asia during 1993-2010 or 2000-2009. High bias in anthropogenic CO2 emissions also leads to stronger land sinks in global land-ocean flux partitioning in our inverse model. The corrected anthropogenic CO2 emissions by CH4 inversion results also produce measurable reductions in the rate of global land CO2 sink increase post-2002, leading to a better agreement with the terrestrial biospheric model simulations that include CO2-fertilization and climate effects.

  BG04-D3-PM1-P-019 (BG04-A008)
 
Plant Regrowth as a Driver of Recent Enhancement of Terrestrial Carbon Uptake
Masayuki KONDO1#+, Kazuhito ICHII1, Prabir PATRA2,3, Benjamin POULTER4, Leonardo CALLE5
1 Chiba University, Japan, 2 Japan Agency for Marine-Earth Science and Technology, Japan, 3 Tohoku University, Japan, 4 NASA Goddard Space Flight Center, United States, 5 Montana State University, United States
#Corresponding author: redmk92@gmail.com +Presenter

Attributing drivers of net carbon uptake in detail leads to clarification of causes for the recent enhancement of carbon dioxide (CO2) uptake by the terrestrial biosphere. The increasing strength of the land uptake in the 2000s has been attributed so far to a stimulating effect of rising atmospheric CO2 on photosynthesis (CO2 fertilization). However, it is still arguable whether the CO2 fertilization is a dominant cause for the recent enhancement of CO2 uptake because, in addition to the level of atmospheric CO2, the terrestrial biosphere has undergone historical changes through land use and management. CO2 emissions resulting from LUC activities account for ~9% of the total global anthropogenic CO2 emissions, therefore changes in LUC could affect the course of the net sink-source pattern of CO2 over time.

Here using an ensemble of biosphere models, we show a decadal-scale carbon uptake enhancement is induced not only by CO2 fertilization, but also an increasing uptake by plant regrowth from past land use changes (LUC), with its effect most pronounced in eastern North America, southern and eastern Europe, and southeastern temperate Eurasia. Our analysis indicates that ecosystems in North America and Europe have established the current productive state through regrowth over a half-century, and those in temperate Eurasia are still in a recovering stage from active LUC in the 1980s. As the strength of model representation of CO2 fertilization is still in debate, plant regrowth might have a greater potential to sequester carbon than indicated by this study.

  BG04-D3-PM1-P-020 (BG04-A014)
 
Teleconnection Based Terrestrial Carbon Cycle Forecasting and Attribution System
Benjamin POULTER1#, Lesley OTT1, Ashley BALLANTYNE2, Philippe CIAIS3, Ana BASTOS3, Abhishek CHATTERJEE4, Stephen SITCH5, Leonardo CALLE6+
1 National Aeronautics and Space Administration, United States, 2 University of Montana, United States, 3 Institut Pierre Simon Laplace, France, 4 NASA Goddard Space Flight Center, United States, 5 University of Exeter, United Kingdom, 6 Montana State University, United States
#Corresponding author: benjamin.poulter@nasa.gov +Presenter

Interannual variations in the atmospheric growth rate of carbon dioxide concentrations are driven primarily by terrestrial ecosystems, which respond on a relatively fast timescale to climate variability. Currently, dynamic global vegetation models (DGVM) are commonly used to diagnose the role of climate, land use, and carbon dioxide concentrations on the exchange of carbon between the land and atmosphere. DGVM models represent first-order processes that control carbon uptake, allocation, and release from ecosystems, but can be prone to high uncertainties and computational challenges related to acquiring forcing data with low latency. Here we present an empirical approach using climatic teleconnections to estimate net-carbon exchange between the land and atmosphere over the past 40 years and use the model to forecast carbon exchange on seasonal timescales. We use an ensemble of climatic teleconnections fitted against data from the TRENDY dynamic global vegetation model ensemble providing fluxes of net ecosystem exchange. The empirical model accounts for uncertainties and interactions between teleconnections and their temporal lags on a per-pixel basis for the past 40 years. Seasonal climate forecasts (one to seven month lead time) from the NASA Global Modeling and Assimilation Office Goddard Earth Observing System Model are used to forecast teleconnection phases, which are then used to predict net carbon uptake. The model is applied to explain recent terrestrial carbon uptake anomalies that occurred in 2011, 2014, and 2016, and is used to forecast the 2017 terrestrial land sink. Integrating process-based approaches and climatic teleconnections within empirical models can potentially allow for rapid assessment and interpretation of historical carbon uptake anomalies and to forecast seasonal.

  BG04-D3-PM1-P-021 (BG04-A015)
 
Detecting Vegetation Changes Induced by Afforestation in China Using Multiple Satellite Products
Kazuhito ICHII1,2#+, Yuji YANAGI3, Jingfeng XIAO4, Masayuki KONDO1
1 Chiba University, Japan, 2 National Institute for Environmental Studies, Japan, 3 Japan Agency for Marine-Earth Science and Technology, Japan, 4 University of New Hampshire, United States
#Corresponding author: kazuhito.ichii@gmail.com +Presenter

The use of multiple satellite-based data products can help analyze and understand changes in terrestrial vegetation cover and terrestrial CO2 cycles. Terrestrial vegetation environment in China is known as affected by many changes including both natural and anthropogenic changes. Especially, afforestation and land use change are considered as two of the most important factors. To date, satellite-based monitoring of terrestrial vegetation changes in China is conducted at either regional or country scales with coarse spatial resolutions. In this study, we analyzed vegetation changes in China from 2000 to 2015 using multiple satellite-based data products with higher spatial resolution. The products include ALOS PALSAR Forest/NonForest Map, LANDSAT based land cover map, MODIS land cover (MCD12Q1), vegetation continuous field (MOD44B) and vegetation index (MOD13A2). First, we assessed changes in forest cover from 2000 to 2015 using multiple forest cover products. We confirmed that two MODIS datasets, MCD12Q1 and MOD44B, were consistent with high resolution satellite based products (LANDSAT and ALOS PALSAR) and forest inventory with slight negative bias for MOD44B. The changes of forest cover by MCD12Q1 and MOD44B products were consistent, showing large increases in forest cover in central China, where afforestation were intensively conducted. Second, we analyzed temporal trends of vegetation index, and their dependency on land cover changes. Clear relations between temporal trends of vegetation index and land use change history were obtained; the highest increasing trends were observed in the grid cells where land use change from non-forest to forest occurred. These multiple pieces of evidence show that afforestation policy in China significantly affects forest areas and terrestrial vegetation for the 2000 to 2015 period.

  BG04-D3-PM1-P-022 (BG04-A017)
 
Global Terrestrial Carbon Budget Simulated by VISIT Model
Etsushi KATO#+
Institute of Applied Energy, Japan
#Corresponding author: e-kato@iae.or.jp +Presenter

Terrestrial sink and carbon uptake and losses affected by the anthropogenic land use and land-use change are the two largest components of the uncertainties in the evaluation of global carbon budget (Le Quéré et al. 2017). In this presentation, processes considered in the modelling of the terrestrial carbon budget by VISIT model are shown and how each component is affecting the calculated NBP. Also, sensitivity from land-use data (LUHv1 and LUHv2) is evaluated.

Reference

Le Quéré et al., 2017, Earth Syst. Sci. Data Discussions, https://doi.org/10.5194/essd-2017-123

  BG05-SE-D3-PM1-P-009 (BG05-SE-A009)
 
Remotely Measuring the Potential Link Between Vegetation Health and Extent, and Diffuse Soil Gas Emissions Using HyspIRI-Like Data at Kilauea Volcano, Hawaii
Chad D. DEERING1#+, Isabella MARIOTTO2, Christie TORRES1
1 Michigan Tech University, United States, 2 University of New Mexico, United States
#Corresponding author: cddeerin@mtu.edu +Presenter

The replenishment of a shallow magma reservoir can signal a) the onset of an eruption at a dormant volcanic system (e.g., Mauna Loa) or, b) significant changes in eruptive behavior at an already active volcano (e.g., Kīlauea). Rising magma ultimately results in a flux of volatiles through the ground (e.g., CO2 and H2S) and from active vent plumes (e.g. CO2 and SO2), particulate matter, and/or thermal energy, onto Earth’s surface and into the atmosphere. Detecting and characterizing these fluxes and the effects that they have on the health and extent of local vegetation is important for quantifying aspects of magma ascent dynamics and shallow conduit processes and for recognizing significant changes in a volcano’s behavior and forecasting volcanic events and hazards. We have analyzed HyspIRI-like data acquired during the AVIRIS/MASTER airborne campaign over Hawaii in Jan-March 2017. The results of our work show the effects that volcanic processes have on the surrounding landscape and show promise that it can be quantified and regularly measured using HyspIRI remote sensing data. A spatial relationship appears between surface temperature, soil gas emissions (H2S, CO2), and the extent and health of surface vegetation cover.

  BG06-AS-D3-PM1-P-017 (BG06-AS-A006)
 
The Improvement of Using Aerosol Information from CAPI/Tansat Nadir Observation in CO2 Retrieval
Xi CHEN1#+, Dongxu YANG2, Yi LIU1, Zhaonan CAI1
1 Chinese Academy of Sciences, China, 2 Institute of Atmospheric Physics, Chinese Academy of Sciences, China
#Corresponding author: chenxilageo@mail.iap.ac.cn +Presenter

Aerosols affect the radiative transfer in the absorption bands of carbon dioxide (CO2), thereby contributing to the uncertainties in the retrieval of CO2 from space. A Cloud and Aerosol Polarimetric Imager (CAPI) has been designed to fly on the Chinese Carbon Dioxide Observation Satellite (TanSat) and provide aerosol and cloud information to facilitate the measurements of CO2. Based on previous study about aerosol retrieval ability of CAPI, this study aims to estimate the improvement of XCO2 posterior error if aerosol information from CAPI measurements are used in TanSat CO2 retrieval. We simulate TanSat hyperspectral observations using a forward model, from which the Jacobians of CO2 concentration and aerosol properties could also be calculated to get the interference error and forward model parameter error of XCO2 from the uncertainties of aerosol parameters, as well as XCO2 posterior error according to optimal estimation theory. Five aerosol parameters in bimodal aerosol model are selected in the state vector of CO2 retrieval and the results of four types of aerosols with different properties from AERONET are compared. Both the interference error from aerosols and the improvement of XCO2 error due to aerosol measurements are related to aerosol mixture described by fine mode fraction (fmfv) and highly depend on aerosol optical depth (AOD). When AOD changes from 0.1 to 1.0 with 0.1 to 0.9 fmfv, the total error in XCO2 due to aerosols ranges from 0.05 ppm to 1.1 ppm. After the a priori uncertainties of aerosol properties are improved from CAPI measurements, XCO2 posterior error could be reduced 0.1 ppm in average, depending on AOD, fmfv and solar zenith angle (SZA).

  BG06-AS-D3-PM1-P-018 (BG06-AS-A008)
 
Diurnal and Seasonal Variations of Carbon Dioxide Concentration and Flux Between Tidal Flat and Atmosphere at the Hampyeong Bay
Yoon Hwan SO#+, Dong Hwan KANG, Byung Hyuk KWON, Il-Kyu KIM
Pukyong National University, South Korea
#Corresponding author: lunaace@naver.com +Presenter

The Observations of CO2 flux, concentration and soil temperature were carried out in the Hampyeong Bay tidal flat at dawn in summer (2012) and in winter (2012 and 2013), and in the morning, afternoon, and evening. It was found that the diurnal variation in the CO2 flux in the Hampyeong Bay tidal flat resulted in the highest emission at dawn, and had a high uptake in the morning and afternoon. The diurnal variation in CO2 concentrations was highest in the dawn and lowest in the morning and afternoon, both in summer and winter. In summary variations in CO2 flux and concentration in the Hampyeong Bay tidal flat are characterized by photosynthesis activities in plant plankton during the day and by the respiration activity in habitats at night or at dawn.

  BG06-AS-D3-PM1-P-019 (BG06-AS-A013)
 
The Proposal for the Next Generation Tansat
Maohua WANG1#+, Lin QIU2
1 Chinese Academy of Sciences, China, 2 Shanghai Advanced Research Institute, Chinese Academy of Sciences, China
#Corresponding author: wangmh@sari.ac.cn +Presenter

The global climate change and greenhouse gas emission issue have become the hottest topics of international cooperation and scientific frontiers, because they are not only related to the sustainable development of every country but also the future of the earth. China is actively promoting the construction of ecological civilization and encouraging green, low-carbon, and climate adaptive and sustainable development. In December 22, 2016, China successfully launched the global CO2 monitoring experiment satellite (TanSat), and became the third country after Japan and the United States to monitor greenhouse gases through its own carbon satellite. The designed service life of TanSat is three years, in order to continue providing the world with abundant CO2 monitoring data for addressing global climate change in the future, it needs to start the next generation of TanSat programs as soon as possible. Meanwhile, the environmental problems China are facing now, include not only greenhouse gas emissions, but also the increasingly severe air pollution. It is also an important research direction to use satellite to monitor air pollution. Due to the development of satellite observation technology, it is now possible to monitor GHGs and air pollutants simultaneously using satellites and similar data processing protocol. Furthermore, instead of a single satellite such as TanSat, the next generation TanSat should be a constellation which routinely monitor the earth surface with high spatial and temporal resolution. Based on the next generation of TanSat, a ground-space carbon monitoring system will be build up, integrating carbon emission data and developing carbon emission database and accounting methods, to provide scientific and technical support for addressing climate change and air pollution control in covered regions and countries, to provide policy makers with independent data to help achieve the global emission reduction goal early.

  BG06-AS-D3-PM1-P-020 (BG06-AS-A021)
 
Inversion Systems for Surface CO2 and CH4 Flux Estimates in GOSAT/GOSAT-2 Projects
Makoto SAITO#+, Tazu SAEKI, Richao CONG, Tatsuya MIYAUCHI, Tsuneo MATSUNAGA, Shamil MAKSYUTOV
National Institute for Environmental Studies, Japan
#Corresponding author: saito.makoto@nies.go.jp +Presenter

Greenhouse gases Observing Satellite (GOSAT) has been monitoring atmospheric column carbon dioxide (XCO2) and methane (XCH4) concentrations from space since its launch in January 2009. The primary goal of GOSAT project is to successfully estimate global carbon budget on subcontinental scales using spatiotemporal distribution of XCO2 and XCH4. GOSAT observations have provided the basis for assessments of the values of space-based measurements of CO2 and CH4 concentrations. Additionally, GOSAT-2 which is the successor of GOSAT is scheduled for launch in the end of 2018. GOSAT-2 aims to monitor spatiotemporal distribution of greenhouse gases with higher level of accuracy and to improve the number of available observation data. This work summarizes GOSAT level4 products on global CO2 and CH4 flux estimates based on an inversion system and the benefit of GOSAT observations for the study of global carbon cycle. We also introduce a new inversion system which is under construction as GOSAT-2 level 4 system.

  BG06-AS-D3-PM1-P-021 (BG06-AS-A022)
 
Greenhouse Emission from Manure Management at California Dairies: Linking Observations Across Scales for Improved Understanding of Emissions
Francesca HOPKINS#+
University of California, Riverside, United States
#Corresponding author: fhopkins@ucr.edu +Presenter

At the global scale, variations in methane emissions over the past several decades have drawn attention to our incomplete understanding of methane budgets. Atmospheric observations at regional to global scales have shown that agricultural methane emissions are likely underestimated in greenhouse gas budgets; however, reasons for this discrepancy are not well understood. We present results from airborne imaging of methane, combined with a new high-resolution bottom-up dataset for California to demonstrate shortcomings in current estimates of methane emissions from manure management practices in dairy farming. We then present a plan to systematically evaluate methane and nitrous oxide emissions from manure management at California dairies by making a coordinated suite of measurements across diverse scales. These measurements will range from on-farm assessments of methane fluxes and their biophysical drivers at the scale of individual manure handling system components to regional emissions estimates from two ground-based solar Fourier Transform Spectrometers (EM27 Sun) and inversion studies of atmospheric observations. Farm-based measurements will be scaled up using process models for comparison to regional observations with the goal of understanding why emission estimates at different scales yield disparate results. Through this experiment, we hope to generate robust emission estimates and recommendations for future monitoring of manure management-derived methane that will provide a baseline against which California’s methane mitigation efforts can be assessed and verified.

  BG06-AS-D3-PM1-P-022 (BG06-AS-A024)
 
Carbon Balance of Two Different Cropping Systems over a Paddy Field in South Korea
Yongseok KIM+, Kyo-Moon SHIM#, Myung-Pyo JUNG, Kee-Kyung KANG
National Institute of Agricultural Sciences, South Korea
#Corresponding author: kmshim@korea.kr +Presenter

By sequestering significant amounts of carbon (C) from the atmosphere, forests, and grasslands offer a strategy to mitigate global warming. In contrast, agricultural systems are often regarded as potential sources for atmospheric carbon dioxide (CO2). However, changes in cropping systems and agricultural practices are being considered as possible ways to mitigate climate change by increasing carbon storage in crop and soils. CO2 and methane (CH4) were measured in a rice-barley double cropping and rice mono cropping paddy fields, which are located in the southwestern coast of Korea, over a one-year period. Net ecosystems CO2 exchange (NEE) and ecosystem respiration (Re) were estimated by the eddy covariance (EC) method, and an automatic open/close chamber (AOCC) method was used to measure CH4 fluxes. Environmental factors (solar radiation, air temperature, precipitation etc.) were also measured along with fluxes. After the quality control and gap-filling, the observed fluxes were analyzed. As a result, NEE was –603.0 and –471.5g C m-2 yr-1 in rice-barley double cropping and rice mono cropping paddy field, respectively. CH4 emissions increased during the course of flood days and were similar in two cropping paddy field. According to rough results considering only fluxes of CO2 and CH4, it was estimated that the carbon absorption in rice-barley double cropping paddy field was higher than that in rice mono cropping paddy field by 128.9g C m-2 yr-1.

This study was carried out with the support of Research Program for Agricultural Science & Technology Development (Project No. PJ01229301), National Institute of Agricultural Sciences, Rural Development Administration, Republic of Korea.

  BG06-AS-D3-PM1-P-023 (BG06-AS-A025)
 
X_CO2 Retrieval Using the Yonsei Carbon Retrieval Algorithm
Jaemin HONG1#+, Jhoon KIM1, Yeonjin JUNG2, Woogyung KIM3, Hartmut BOESCH4, Tae-Young GOO5, Ja-Ho KOO1
1 Yonsei University, South Korea, 2 Harvard-Smithsonian Center for Astrophysics, United States, 3 NASA Goddard Space Flight Center, United States, 4 University of Leicester, United Kingdom, 5 Korea Meteorological Administration, South Korea
#Corresponding author: rookie820@gmail.com +Presenter

As the temperature of the earth has been increasing since the Industrial Revolution, it is necessary to monitor the sinks and sources of atmospheric carbon dioxide (CO2), which have been known to have the largest impact on the greenhouse effect. Recently, several satellites with hyperspectral short-wave IR sensor started to operate. Among those satellites, Orbiting Carbon Observatory-2 (OCO-2) was launched on September 2014, and gives about a million of observations every day with resolution and accuracy needed to detect regional scale fluxes. In this study, we developed a retrieval algorithm for atmospheric CO2 density using OCO-2 measurement; Yonsei Carbon Retrieval (YCAR-OCO). The YCAR is based upon the Optimal Estimation Method (Rogers, 2000) which utilizes auxiliary information, a priori, as well as satellite measurement. A priori information which reflects the realistic atmospheric conditions effectively is a key to successful retrieval. Especially aerosol-related a priori information is important because aerosols scatter light and modify its path length and because aerosols have a highly variable temporal and spatial distribution. For these reasons, we used near-real time data from the Moderate-resolution Imaging Spectrometer (MODIS) and the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). We also developed CO2 retrieval algorithm using GOSAT measurement in the preceding studies; YCAR-GOSAT. For validation, the results of YCAR-GOSAT was compared with the Total Carbon Column Observation Network (TCCON) ground-based observations at Tsukuba, Japan. From 2011 to 2012, the root-mean-square error was 1.90 ppm. The results of YCAR-OCO and TCCON was also compared.  From 16 November 2014 to 11 May 2015, 6 cloud-free scenes were selected. For each scene, the mean bias between the retrieval results of YCAR-OCO and TCCON varied from -0.555 ppm to 2.763 ppm, with the outlier of -18.754 ppm.

  BG07-D3-PM1-P-005 (BG07-A001)
 
Arsenic Binding Characteristics to Humic Substances in the Organic Sediments
Junko HARA#+
National Institute of Advanced Industrial Science and Technology, Japan
#Corresponding author: j.hara@aist.go.jp +Presenter

Humic substances, widely distributed in soil and natural water, have the complexation ability for reacting with major metals and trace of toxic elements, and it acts on the mobility of the affected elements. This research focuses on the accumulation of arsenic (As) into humic substances, and we discuss the arsenic trapping mechanism of humic substances based on sequential extraction and arsenic bound in each humic substance.

Inorganic arsenic is basically bound to Fe and Al (hydr)oxides, Mn oxides, and sulfides and is fixed in sediments as inorganic arsenic. This is the basic geochemical phenomena in environments, but organic rich sediments abound in organic-form arsenic in the sediments, and arsenic in humic substances reflect the absorption and metabolization of the organic origin of each organic species. Extracted cellulose from the organic sediments, an organic compound of plant origin, was found to be abundant in As=S and As (III)=O bonds, and higher As was detected in sulfur-rich sediments. This corresponds with physiological activity of As in plants. In addition, humic acid and fulvic acids were obvious in methylated As bound reflected ecological transitions in marine organisms, small animals, and microorganisms. Among them, hydrophilic fulvic acid has As(III,V)=C, As(V)=O, and water-soluble methoxy, methyl, and ethyl groups. Humic acids and hydrophobic fulvic acids have As(III, V)=C and fat-soluble ether groups, and the As concentrations in hydrophobic fulvic acids were lesser than that in other acids. Regarding fulvic acid, water-soluble hydrophilic fulvic acid has higher accumulation ability than the fat-soluble hydrophobic fulvic acid in marine organisms. Aromatic groups commonly abound in humic acid and that raise the metal complex formation accumulate arsenic into humic acids. Although humic substances are conglomerates of several organic compounds, accumulation of arsenic into humic acid and fulvic acids reflect the arsenic absorption properties of the organic origin of humic substances.

  BG08-IG-D3-PM1-P-005 (BG08-IG-A003)
 
Optimized Fertigation Maintains High Crop Yield and Mitigates N2O and NO Emissions in a Wheat/Maize Cropping System
Xin ZHANG1+, Guangmin XIAO1, Wenliang WU1, Hu LI2, Ligang WANG2, Fanqiao MENG1#
1 China Agricultural University, China, 2 Chinese Academy of Agricultural, China
#Corresponding author: mengfq@cau.edu.cn +Presenter

Agricultural soil is a major source of both N2O and NO. In northern China, optimized N fertilization and water-saving irrigation have been suggested as effective farming practices to improve nutrient and water use efficiency while maintaining a high crop yield. A field experiment consisting of flood irrigation treatments (FN600, conventional N fertilization of 600 kg N ha-1 a-1 and flood irrigation; FN0, no N input and flood irrigation) and drip fertigation (N0, no N input and drip irrigation; N420, optimized N fertilization of 420 kg N ha-1 a-1 and drip irrigation; N600, conventional N fertilization of 600 kg N ha-1 a-1 and drip irrigation) was initiated in Oct 20, 2015 and the N2O and NO emissions was monitored in the period of 2015-2016. Compared with FN600 treatment, N600 saved 70.2% (wheat season) and 36.4% (maize season) of water and exhibited no significant differences of N2O emission in the wheat season, but significantly reduced the N2O emission (19.9%) in the maize season; N600 increased NO emission in the wheat and maize seasons by 20.9% and 11.0%, respectively. Compared with N600 treatment, N420 (optimized fertigation, i.e., saving of 30% N fertilizer) significantly decreased N2O and NO emission by 21.8% and 29.8% in the wheat season, by 31.5% and 41.6% in the maize season and achieved a higher crop yield (1.7%). The direct emission factors of N2O and NO were 0.19%–0.25% and 0.21%–0.27% for the wheat season, 0.38%–0.63% and 0.34%–0.42% for the maize season, respectively. Considering of the higher productivity, saved water resources and lower N2O and NO emissions, drip irrigation combined with optimized N fertilization is recommended in the northern China, yet its expansion currently faced the obstacles of water pricing in the region.

  BG08-IG-D3-PM1-P-006 (BG08-IG-A004)
 
Microbial Diversity and Community Structure of Sulfate-Reducing and Sulfur-Oxidizing Bacteria in Sediment Cores from the East China Sea
Yu ZHEN#+
Ocean University of China, China
#Corresponding author: zhenyu@ouc.edu.cn +Presenter

Sulfate-reducing bacteria (SRB) and sulfur-oxidizing bacteria (SOB) have been studied extensively in marine sediments because of their vital roles in both sulfur and carbon cycles, but the available information regarding the highly diverse SRB and SOB communities is not comprehensive. High-throughput sequencing of functional gene amplicons provides tremendous insight into the structure and functional potential of complex microbial communities. Here, we explored the community structure, diversity and abundance of SRB and SOB simultaneously through 16S rRNA, dsrB and soxB gene high-throughput sequencing and quantitative PCR analyses of core samples from the East China Sea. Overall, high-throughput sequencing of the dsrB and soxB genes achieved almost complete coverage (>99%) and revealed the high diversity, richness and OTU numbers of the SRB and SOB communities, which suggest the existence of an active sulfur cycle in the study area. Further analysis demonstrated that rare species make vital contributions to the high richness, diversity and OTU numbers obtained. Depth-based distributions of the dsrBsoxB and 16S rRNA gene abundances indicated that the SRB abundance might be more sensitive to the sedimentary dynamic environment than those of total bacteria and SOB. In addition, the results of unweighted pair group method with arithmetic mean (UPGMA) clustering analysis and redundancy analysis (RDA) revealed that environmental parameters, such as depth and dissolved inorganic nitrogen (DIN) concentrations, and the sedimentary dynamic environment, which differed between the two sampling stations, can significantly influence the community structures of total bacteria, SRB and SOB. This study provided further comprehensive information regarding the characteristics of SRB and SOB communities.

  BG08-IG-D3-PM1-P-007 (BG08-IG-A007)
 
Shifts in Stream Hydrochemistry in Responses to Typhoon and Non-Typhoon Precipitation
Chung-Te CHANG1#+, Jr-Chuan HUANG1, Lixin WANG2, Teng-Chiu LIN3
1 National Taiwan University, Taiwan, 2 Indiana University-Purdue University Indianapolis, United States, 3 National Taiwan Normal University, Taiwan
#Corresponding author: changchuante@gmail.com +Presenter

The intensity and frequency of extreme climatic events such as tropical cyclones is projected to increase in the warming climate. However, few studies have examined the responses of hydrochemical processes to climate extremes. To fill this knowledge gap, we compared the relationship between stream discharge and ion input-output budget during typhoon and non-typhoon periods in four subtropical mountain watersheds with different levels of agricultural land cover in northern Taiwan. The results indicated that the high predictability of ion input-output budgets using stream discharge during non-typhoon periods largely disappeared during the typhoon periods. For ions such as Na+, NH4+, and PO43-, the typhoon periods and non-typhoon periods exhibited opposite discharge-budget relationships. In other cases, the discharge-budget relationship was driven by the typhoon period, which consisted of only 7% of the total time period. Watersheds with a 17‒22% tea plantation cover showed large increases in NO3- export with increases in stream discharge. In contrast, watersheds with 93‒99% forest cover showed very mild or no increases in NO3- export with increases in discharge and very low levels of NO3- export even during typhoon storms. The results suggest that even mild intervention of the natural vegetation could largely alter hydrochemical processes. Our analysis of ion input-output budget also illustrates that hydrochemistry during typhoon storms are highly variable, and models built from regular periods have low predictability of ion budgets during extreme storm periods. The significant shifts in hydrochemical responses between regular and typhoon precipitation indicates that hydrological models should separate hydrochemical processes into regular and extreme conditions to better capture the whole spectrum of hydrochemical responses to a variety of climate conditions.

  BG08-IG-D3-PM1-P-008 (BG08-IG-A010)
 
Structure Analysis of Amino Acid Polymer Synthesized from an Amino Acid Precursor
Miho SASE#+, Hajime MITA
Fukuoka Institute of Technology, Japan
#Corresponding author: s14g2022@bene.fit.ac.jp +Presenter

There are several hypothesis of the origin of life. Organic compounds were evolved from simple compounds to complicate ones. Finally, the first life would be born from those compounds on the primitive Earth. This is a principle of “Chemical evolution” hypothesis by Oparin. If the conditions for the origins of life are mimicked completely, we would be able to trace the process. Present organisms are consisted of protein mainly, and protein is a polymer of amino acids. Therefore, we considered that amino acid is an important minimum unit of biomolecules. Amino acid and its precursor were found in many cosmic samples as the moon fines and meteorites. Moreover, it was reported that low molecular organic compound such as amino acid synthesize by discharge electricity or ultraviolet irradiation in the simulated cosmic or primitive Earth atmosphere. For this reason, amino acid and its precursor were common compounds in primitive environment. Then, it polymerized and lead to the key compounds for the first life.

In this study, we try to synthesize poly amino acid from amino acid and its precursor under the conditions that might be existed at the primitive Earth. The amino acid precursor used for the thermal polymerization was malate monoammonium salt. We analyzed the molecular weight distribution of poly amino acids using mass spectrometry and functional group changes by infrared absorption spectrometry. From single precursor, there are several patterns in the terminal structures of synthesized polymers. In addition, characteristic of co-polymerized products were also studied. We discussed a new knowledge of chemical evolution and biotic organization.

  BG08-IG-D3-PM1-P-009 (BG08-IG-A013)
 
Analysis of Moor Hot Spring
Saori MIKURIYA#+, Hajime MITA
Fukuoka Institute of Technology, Japan
#Corresponding author: s14g2044@bene.fit.ac.jp +Presenter

A moor hot spring is one of unique hot spring among various ones. It shows characteristic color ranging from yellowish-brown to black. It also has a smooth touch and fragrance. For example, the most famous moor hot spring in japan is Tokachigawa Onsen in Hokkaido. There is a deposit of peat around Tokachigawa area, because it is cool and the biomass is difficult to decompose by microorganisms. Therefore, it contains the humic substances from peat or lignite. However, detailed chemical analyses of organic compounds in moor hot spring are not studied well. We analyze the organic composition of several moor hot spring by various chemical analytical methods. In addition, hot water extracts from peat or lignite were also analyzed as same way and organic compositions of the extracts were compared with those of moor hot springs. 

We collected three moor hot spring water in Oita city. The moor hot spring water was concentrated and analyzed using LCMS for investigating chemical composition of relatively small molecules and IR for investigating function groups of total organics. Hot water extracts from lignite were also analyzed with several extraction condition, for example, difficult heating time, temperature.

LCMS results showed many identical peaks in molecular weight range from 100 to 200. However, there was few peaks in the molecular weight over 400. There were no significant change of chemical substances in the different extract conditions, but small change in the composition.

  BG08-IG-D3-PM1-P-010 (BG08-IG-A014)
 
A Biosynthetic and Metabolic Perspective of Stable Isotopic Fractionation in Food Webs
Yuko TAKIZAWA#+, Yoshito CHIKARAISHI
Hokkaido University, Japan
#Corresponding author: takizaway@lowtem.hokudai.ac.jp +Presenter

Fractionation in carbon and nitrogen isotopes between a consumer and its diet has long been employed as a conventional approach to understand trophic connections among organisms in ecosystems. However, a little is known the biosynthetic and metabolic factors responsible for the trophic isotopic fractionation in consumer species. In the present study, we determined the isotopic fractionations for amino acids in four pairs of consumer–resource invertebrates: sea slug – sponge, and ladybug beetle – the aphid, collected from coastal and terrestrial environments, respectively; and green lacewing – the fall armyworm, and the green lacewing – green lacewing, reared in laboratory controlled feeding experiments, to illustrate a biosynthetic and metabolic perspective of the isotopic fractionations. The fractionation in nitrogen isotopes for these combinations are well consistent with those in many other combinations reported in previous studies, which further validates a standard scenario: the isotopic fractionation of 15N/14N mirrors the metabolic activity of amino acid deamination. On the other hand, The fractionation in carbon isotopes have a trend far different from that in nitrogen isotopes, which allows us to predict that the isotopic fractionation of 13C/12C mirrors the biosynthetic activity of amino acid production. These bridged perspective between the isotopic fractionation and its responsible mechanism will provide for further refinements in interpretation of the isotopic fractionations in ecological food webs.

  BG08-IG-D3-PM1-P-011 (BG08-IG-A015)
 
Is Isotopic Fractionation in Carbon Isotopes Coupling with that in Nitrogen Isotopes in Food Webs?
Yoshito CHIKARAISHI#+, Yuko TAKIZAWA
Hokkaido University, Japan
#Corresponding author: ychikaraishi@lowtem.hokudai.ac.jp +Presenter

We have long employed stable carbon and nitrogen isotope ratio analysis as a conventional tool for illustrating food web structures in diverse ecosystems, which is highly useful in understanding the source and its transfer process of carbon and nitrogen atoms in ecological and biogeochemical cycles. This isotope analysis is based on empirical observation that organisms are enriched in 13C by 0-1‰ and in 15N by 3-4‰ at the elevation of each trophic hierarchy in food webs, and thus we have frequently found a single positive correlation between carbon and nitrogen isotope ratios from primary producers to top predators along a food chain in diverse ecosystems. However, a little is known fractionating and coupling mechanisms associated with the trophic transfer of organic resources within a single organism and in turn food webs.

In the trophic transfer, it has long been believed that the preferential cleaving of 12C-12C bond during decarboxylation of pyruvate to produce acetyl-CoA causes the enrichment in 13C on the residual pool of pyruvate (which is a substrate for several amino acids), whereas the preferential cleaving of 14N-12C bond during deamination of amino acids to produce keto acids causes that in both 13C and 15N on the residual pool of amino acids. Thus it seems to discrepancy if the former process is major factor but not to discrepancy if the latter process is major factor controlling the positive correlation between carbon and nitrogen isotope ratios observed. In the presentation, we would like to discuss this fundamental issue, based on theoretical and experimental knowledge on the isotopic fractionation of organic compounds.

  BG10-IG-D3-PM1-P-007 (BG10-IG-A004)
 
Assessing Global Phosphorus Losses from Major Crop Cultivations with an Integrative Crop–Soil–Management Perspective
Wenfeng LIU#+, Hong YANG
Swiss Federal Institute of Aquatic Science and Technology, Switzerland
#Corresponding author: wenfeng.liu@eawag.ch +Presenter

Phosphorus (P) balance of croplands is controlled by a variety of factors: e.g. fertilization, runoff and erosion, transformations of P in soil, and crop uptake followed by plant harvest. In order to investigate the effect of P fertilization conditions on crop yields and to quantify P losses reliably, it is of importance to integrating plant–soil–management interplays into consistent modelling systems. However, previous studies on P losses on large scales did not consider the interactions among these factors. In this study, we will use a large-scale/grid-based crop model Python-based Environmental Policy Integrated Climate (PEPIC), which is able to simulate complex soil–water–climate–management systems related to agricultural P dynamics, to estimate global P losses from three major cereal crop cultivations, i.e., maize, rice, and wheat. The PEPIC model will be fed by detailed P input datasets. We will explore global hot-spot regions with high P losses and their spatial correlation with crop yields. Regions with excessive P applications will be identified. We will further present several pathways to reduce global P losses without compromising crop yields through fertilization, soil erosion, and crop residues management based on scenario simulations. This study provides useful information for guiding policy makers to formulate efficient strategies for the purpose of tackling P-driven environmental problems.

  BG10-IG-D3-PM1-P-008 (BG10-IG-A010)
 
Tibetan Plateau Permafrost Carbon Change of the Past 40 Years
Duoying JI#+, Wenbin SUN
Beijing Normal University, China
#Corresponding author: duoyingji@bnu.edu.cn +Presenter

Permafrost is a climatologically important feature of the Tibetan Plateau, and it has been treated as an indicator of climate change and is highly sensitive to climate changes. Changes in permafrost are likely to influence local energy exchanges, hydrological processes and carbon budgets and hence global climate system. Here, we study the temporal and spatial change of the Tibetan Plateau permafrost extent, active layer thickness and soil organic carbon budgets during the past four decades, using results from seven offline land surface models participated in Permafrost Carbon Network Model Intercomparison Project (PCN-MIP). The models we analyzed here adopt different parameterization schemes related to permafrost soil thermal-hydrological dynamics and carbon dynamics. For example, the resolved soil column depth ranges from 3.4m to 47m, some models have implemented surface organic layer effects and vertical resolved soil organic carbon dynamics while others not. All these differences in representing permafrost processes could result in large uncertainties on permafrost change over the past four decades. Our results show that Tibetan Plateau permafrost extent declines from 900 to 2400 km2yr−1 between models. The change of terrestrial carbon pools also shows large uncertainties under global warming, the soil carbon pool changes from -30.8 to 25.34 gCm−2yr−1 and the vegetation carbon pool changes from -1.67 to 9.27 gCm−2yr−1. This study indicates that more emphasis should be put on improving permafrost thermal-hydrological and soil carbon dynamics to better simulate the Tibet Plateau change under global warming.

  BG10-IG-D3-PM1-P-009 (BG10-IG-A011)
 
Impacts of Sulfate Geoengineering on Terrestrial Carbon Cycle and its Climate Sensitivities
Qian ZHANG, Duoying JI#+
Beijing Normal University, China
#Corresponding author: duoyingji@bnu.edu.cn +Presenter

Climate geoengineering aims to counteract the radiative forcing and the associated warming due to increasing atmospheric greenhouse gases. It would exert considerable impacts on the land–atmosphere CO2 exchange because both photosynthesis and respiration are sensitive to changes in temperature and precipitation. Here we showed results from 10 Earth System Models (ESM) simulations from the stratospheric sulphate injection experiments G3 and G4 of the Geoengineering Model Intercomparison Project (GeoMIP). The multimodel ensemble showed a statistically significant increase of NBP by ~0.6PgC yr-1 in the GeoMIP simulations compared to the results from RCP4.5. In GeoMIP experiments, the relatively lower GPP was outstripped by a stronger reduction in ecosystem respiration, which results in a general increase (>82% vegetated area) in carbon use efficiency over the globe. Partial correlation analysis showed that the interannual sensitivities of NBP to temperature increased by 1 to 2 folds in the GeoMIP experiments, mainly due to higher sensitivities of NPP, yet with large differences among ESMs. In contrast, NBP and NPP are not as sensitive to precipitation in GeoMIP simulations as in the RCP4.5 simulations. Our results suggest that geoengineering in G3 and G4 tends to have a small increase in land carbon uptake but could amplify temperature sensitivity and dampen precipitation sensitivity of terrestrial carbon fluxes significantly.

  BG10-IG-D3-PM1-P-010 (BG10-IG-A015)
 
Long-Term Response of Oceanic Carbon Uptake to Global Warming via Physical and Biological Pumps
Akitomo YAMAMOTO1#+, Ayako ABE-OUCHI2, Yasuhiro YAMANAKA3
1 Japan Agency for Marine-Earth Science and Technology, Japan, 2 The University of Tokyo, Japan, 3 Hokkaido University, Japan
#Corresponding author: akitomo@jamstec.go.jp +Presenter

Global warming is expected to significantly decrease oceanic carbon uptake and therefore increase in atmospheric CO2 and global warming. The primary reasons in previous studies for the change in the oceanic carbon uptake are the solubility reduction due to seawater warming and changes in the ocean circulation and biological pump. However, quantifications of the contributions from different processes to the overall reduction in ocean uptake are still unclear. Herein, we investigate multimillennium response of oceanic carbon uptake to global warming and quantify the contributions of the physical and biological pump to the response using an atmosphere–ocean general circulation model and a biogeochemical model. We found that global warming reduced oceanic CO2 uptake by 13% (30%) in the first 140 years (at 2000 model years), which is consistent with previous studies. Sensitivity studies show that changes in the biological pump via ocean circulation change and solubility change due to seawater warming are dominant processes in the uptake reduction. These results are contrary to most previous studies wherein circulation changes and solubility change from seawater warming are the dominant processes. The weakening of biological production and carbon export induced by lower nutrient supply diminishes the vertical gradient of DIC substantially reducing the CO2 uptake. The weaker deep-ocean circulation decreases the downward transport of CO2 from the surface to the deep ocean, leading to a drop in the CO2 uptake in high-latitude regions. Conversely, weaker equatorial upwelling reduces the upward transport of natural CO2 and therefore enhances the CO2 uptake in low-latitude regions. Because these effects cancel each other, the circulation change becomes a second-order process. Our results suggest that the biological pump plays a significant role in the future oceanic carbon uptake.