Using statistically downscaled atmospheric forcing, we performed a numerical investigation to evaluate future climate's impact on storm surges along the Gulf of Mexico and U.S. east coast. The focus is on the impa...Using statistically downscaled atmospheric forcing, we performed a numerical investigation to evaluate future climate's impact on storm surges along the Gulf of Mexico and U.S. east coast. The focus is on the impact of climatic changes in wind pattern and surface pressure while neglecting sea level rise and other factors. We adapted the regional ocean model system(ROMS) to the study region with a mesh grid size of 7–10 km in horizontal and 18 vertical layers. The model was validated by a hindcast of the coastal sea levels in the winter of 2008. Model's robustness was confirmed by the good agreement between model-simulated and observed sea levels at 37 tidal gages. Two 10-year forecasts, one for the IPCC Pre-Industry(PI) and the other for the A1 FI scenario, were conducted. The differences in model-simulated surge heights under the two climate scenarios were analyzed. We identified three types of responses in extreme surge heights to future climate: a clear decrease in Middle Atlantic Bight, an increase in the western Gulf of Mexico, and non-significant response for the remaining area. Such spatial pattern is also consistent with previous projections of sea surface winds and ocean wave heights.展开更多
本文基于FVCOM(Finite Volume Community Ocean Model)构建了一个覆盖中国渤海、黄海和东海的数值模型,采用NCEP-CFSR风场数据对1509号台风“灿鸿”产生的风暴潮进行模拟,与实测水位数据的对比表明该模型可靠、模拟结果合理。基于此模型...本文基于FVCOM(Finite Volume Community Ocean Model)构建了一个覆盖中国渤海、黄海和东海的数值模型,采用NCEP-CFSR风场数据对1509号台风“灿鸿”产生的风暴潮进行模拟,与实测水位数据的对比表明该模型可靠、模拟结果合理。基于此模型,本文对非线性作用和地形在风暴潮增水过程中的作用进行了研究。首先,重点分析了增水过程中潮汐与风暴潮的非线性作用,结果表明:高潮时非线性作用使增水值降低;低潮时非线性作用使增水值升高。另外,开边界处分别只添加M2、S2和K1分潮,分析天文潮的潮高和周期对非线性作用的影响,结果表明:潮高越高,非线性作用越明显;半日潮的非线性作用较全日潮更明显;并且,增水极值附近出现的半日周期的波动也与非线性作用有关。其次,除了非线性作用,地形对风暴潮的增水也有一定影响,本文改变地形的实验结果表明:坡度越大,增水极值越小。琉球群岛的存在使得东南沿海出现风暴潮增水的面积减小,但使得风暴潮增水的高值区域扩大。展开更多
A multi-index analysis including grain size, major and trace elements is performed on the surface sediments from the northeastern Beibu Gulf to trace the sources of the sediments and to understand the controlling fact...A multi-index analysis including grain size, major and trace elements is performed on the surface sediments from the northeastern Beibu Gulf to trace the sources of the sediments and to understand the controlling factors for elements distribution. The mean grain size exhibits a wide variation ranging from 0.09Φ to 8.05Φ with an average value of 5.33Φ. The average contents of major elements descend in an order of c(SiO_2)>c(Al_2O_3)>c(Fe_2O_3)>c(CaO)>c(MgO)>c(K_2O)>c(Na_2O)>c(TiO_2)>c(P_2O_5)>c(MnO), while those of trace elements exhibit a descending order of c(Sr)>c(Rb)>c(V)>c(Zn)>c(Cr)>c(Pb)>c(Ni)>c(Cu)>c(As). On the basis of elementary distribution characteristics and statistical analyses, the study area is divided into the four zones: Zone I is located in the northeastern coastal area of the gulf, which receives large amount of fluvial materials from local rivers in Guangxi and Guangdong, China, and the Qiongzhou Strait; Zone Ⅱ is located in the center of the study area, where surface sediments exhibits a multiple source; Zone Ⅲ is located in the Qiongzhou Strait, where surface sediments are dominated by materials from the Zhujiang River and Hainan; Zone IV is located in the southwest of the study area, where surface sediments are mainly originated from the Red River and Hainan. The statistical analyses of sediment geochemical characteristics reveal that the grain size, which is mainly influenced by hydrodynamics and mineral composition of terrigenous materials, is the leading factor controlling the elementary distribution.Meanwhile, impacts from anthropogenic activities and marine biogenic process will also be taken into consideration.展开更多
The generation of high-resolution data is increasingly important in understanding the complexities of coastal ocean and developing sound management strategies, especially in view of the long-term impact of severe weat...The generation of high-resolution data is increasingly important in understanding the complexities of coastal ocean and developing sound management strategies, especially in view of the long-term impact of severe weather systems. The impact of severe weather systems, when integrated over time, can be significant when compared with tidal oscillations. This paper presents a study of water transport out of Vermilion Bay in response to a short, intense event associated with a passing atmospheric cold front, and reports the application of an Acoustic Doppler Current Profiler (ADCP) mounted on an Automated Surface Craft (ASC), known as the auto-boat or unmanned boat, developed in our lab at the Louisiana State University, to generate high resolution data accurately at a fraction of the cost of a manned boat. In our study, we used a manned boat and an unmanned boat, each for over 24 h to cover an entire diurnal tidal cycle, to measure flow velocity profiles to calculate the total transport. A stationary ADCP was deployed in the Southwest Pass of the Vermilion Bay from May 2009 to April 2012, providing data almost continuously (with only one major gap), with a 717-day record of water transport between the northern Gulf of Mexico and Vermilion Bay, and demonstrates the importance of the pass in water transport.展开更多
The relationship between the East Asian winter monsoon(EAWM) and East Asian summer monsoon(EASM) during the Holocene is complicated and remains controversial.In this study,analysis of grain size and benthic foraminife...The relationship between the East Asian winter monsoon(EAWM) and East Asian summer monsoon(EASM) during the Holocene is complicated and remains controversial.In this study,analysis of grain size and benthic foraminiferal oxygen isotope,as well as accelerator mass spectrometry ^(14)C dating was performed on a sediment core retrieved from the newly revealed muddy deposit on the northern South China Sea continental shelf.The history of the EAWM and EASM were reconstructed for the last 8200 a BP.Further analysis in conjunction with previously published paleo-climate proxies revealed that the relationship between the EAWM and EASM during the Holocene is more complex than a simple and strict anti-phase one-both negative and positive correlations were identified.The EAWM and EASM are negatively correlated around 7500,4800,4200,3200,and 300 a BP(cooling periods),while positively correlated around 7100,3700,and 2100 a BP(warm periods).In particular,both the EAWM and EASM intensified during the three positive correlation periods.However,we also found that the relationship between these two sub-monsoons is anti-phase during the final phase of particularly hot periods like Holocene Optimum and Medieval warm period.The possible impact from variations of solar irradiance on the relationship between the EAWM and EASM was also discussed.展开更多
A coupled approach based on grain size and geochemical elements is used to trace the provenance of surface sediments and to confirm the distribution patterns of grain size and elements on the continental shelf off wes...A coupled approach based on grain size and geochemical elements is used to trace the provenance of surface sediments and to confirm the distribution patterns of grain size and elements on the continental shelf off western Guangdong Province and northeastern Hainan Island. The mean grain size ranges from 0.05 φ to 7.28 φ with a mean value of 5.60 φ. The average concentra- tions of major elements descend in the order of SiO2 > Al2O3 > CaO > Fe2O3 > K2O > MgO > Na2O > TiO2 > P2O5 > MnO, while those of trace elements exhibit a descending order of Sr > Rb > Zn > V > Cr > Pb > Ni > Cu > As > Cd. On the basis of the distribution patterns of elements and results of statistical analysis, the study area is classified into three zones. Zone I locates on the continental shelf off western Guangdong Province, and the sediments are mainly from Pearl River, Taiwan Residents rivers, and small rivers nearby. Zone II locates in the eastern exit of Qiongzhou Strait and the coastal area off Leizhou Peninsula, and the sediments are mainly from the ero- sion products of Qiongzhou Strait and Hainan Island. Zone III locates off the eastern Hainan Island and the continental shelf deeper than 50 m isobaths, and the sediments are mainly from Hainan Island and coral reef. The influence from open water should also be considered. Results indicate that the grain size is the main controlling factor for major and trace element contents and that anthropo- genic impact and biological activity also play an important role in the distribution of these elements.展开更多
Densely populated coasts are vulnerable to storm damage. Episodic storm-induced redistribution of coastal sediment is known to have major geological and ecological implications [1,2], but little is known about storm-d...Densely populated coasts are vulnerable to storm damage. Episodic storm-induced redistribution of coastal sediment is known to have major geological and ecological implications [1,2], but little is known about storm-driven delta erosion and longshore sediment transport. The Yangtze (Changjiang) Delta and Zhejiang–Fujian coasts (Fig. S1 online) are among the world’s largest coastal depositional systems, and play an important role in supporting China’s socioeconomic development [3,4].展开更多
There is the current lack of comprehensive understanding of the hotspots,frequency,duration,spatiotemporal trends,and physical drivers of marine heatwaves(MHWs)within the Gulf of Mexico(GoM).Here,a series of high-reso...There is the current lack of comprehensive understanding of the hotspots,frequency,duration,spatiotemporal trends,and physical drivers of marine heatwaves(MHWs)within the Gulf of Mexico(GoM).Here,a series of high-resolution satellite and reanalysis products are used to examine their spatiotemporal characteristics,trends,and possible geophysical triggers of MHWs.Possible impacts of the MHW on coral reefs are also discussed.Results reveal an increasing trend in their frequency,duration,and intensities from 1983–2021,particularly after 2016.It identifies MHWs hotspots within the GoM,notably the northern and western shelves and the Loop Current.The study further documents an intense MHW event from late 2020 to early 2021 near the Yucatan Channel,south of 24°N,attributing its development to oceanic processes such as wind anomalies,anticyclonic eddies,and current-driven heat transport anomalies.The occurrence of this MHW event potentially increased thermal stress on the Campeche and Tuxtlas Reef Systems.This research illuminates the increasing trends and impacts of MHWs in the GoM,providing valuable insights for understanding and predicting the effects of climate change on marine ecosystems.展开更多
Seep carbonates were collected from the Alaminos Canyon lease area, Gulf of Mexico. The carbonates are present as slabs and blocks. Bivalve shell and foraminifer are the dominant bioclasts in carbonate. Pores are comm...Seep carbonates were collected from the Alaminos Canyon lease area, Gulf of Mexico. The carbonates are present as slabs and blocks. Bivalve shell and foraminifer are the dominant bioclasts in carbonate. Pores are common and usually filled with acicular aragonite crystals. XRD investigation shows that aragonite is the dominate mineral (98%). Peloids, clotted microfabirc and botryoidal aragonite are de-veloped in carbonate and suggest a genesis linked with bacterial degradation of the hydrocarbons. The δ13C value of bioclasts in carbonate is from-4.9‰ to-0.6‰, indicating that the carbon source is mainly from sea water as well as the small portion incorporation of the seep hydrocarbon. The microcrystalline and sparite aragonite shows the δ13C value from-31.3‰ to-23.4‰, suggesting that their carbon is derived mainly from microbial degradation of crude oil. 14C analyses give the radiocarbon age of about 10 ka. Rare earth elements (REE) analyses of the 5% HNO3-treated solution of the carbonates show that the total REE content of the carbonates is low, that is from 0.752 to 12.725 μg·g-1. The shale-normalized REE patterns show significantly negative Ce anomalies. This suggests that cold seep carbonate is most likely formed in a relatively aerobic environment.展开更多
Here we reported the fatty-acids and their δ13 C values in seep carbonates collected from Green Canyon lease block 185 (GC 185;Sample GC-F) at upper continental slope (water depth:~540 m),and Alaminos Canyon lease b...Here we reported the fatty-acids and their δ13 C values in seep carbonates collected from Green Canyon lease block 185 (GC 185;Sample GC-F) at upper continental slope (water depth:~540 m),and Alaminos Canyon lease block 645 (GC 645;Sample AC-E) at lower continental slope (water depth:~2200 m) of the Gulf of Mexico.More than thirty kinds of fatty acids were detected in both samples.These fatty acids are maximized at C 16.There is a clear even-over-odd carbon number predominance in carbon number range.The fatty acids are mainly composed of n-fatty acids,iso-/anteiso-fatty acids and terminally branched odd-numbered fatty acids (iso/anteiso).The low δ13 C values (-39.99‰ to -32.36‰) of n-C 12:0,n-C 13:0,i-C 14:0 and n-C 14:0 suggest that they may relate to the chemosynthetic communities at seep sites.The unsaturated fatty acids n-C 18:2 and C 18:1 △9 have the same δ13 C values,they may originate from the Beggiatoa/Thioploca.Unlike other fatty acids,the terminally branched fatty acids (iso/anteiso) show lower δ13 C values (as low as -63.95‰) suggesting a possible relationship to sulfate reducing bacteria,which is common during anaerobic oxidation of methane at seep sites.展开更多
基金support provided by the Fundamental Research Funds for the Central Universities(3101000-841413030)NOAA(Grant No.NA11NOS0120033)+2 种基金the National Natural Science Foundation of China(NSFC)(Grant Nos.41506012,9115 21884 and 41506027)the Fund of Global Change and Air-Sea Interaction(Grant No.GAST-GEOGE-03)support by NASA through grant NNX13AD80G
文摘Using statistically downscaled atmospheric forcing, we performed a numerical investigation to evaluate future climate's impact on storm surges along the Gulf of Mexico and U.S. east coast. The focus is on the impact of climatic changes in wind pattern and surface pressure while neglecting sea level rise and other factors. We adapted the regional ocean model system(ROMS) to the study region with a mesh grid size of 7–10 km in horizontal and 18 vertical layers. The model was validated by a hindcast of the coastal sea levels in the winter of 2008. Model's robustness was confirmed by the good agreement between model-simulated and observed sea levels at 37 tidal gages. Two 10-year forecasts, one for the IPCC Pre-Industry(PI) and the other for the A1 FI scenario, were conducted. The differences in model-simulated surge heights under the two climate scenarios were analyzed. We identified three types of responses in extreme surge heights to future climate: a clear decrease in Middle Atlantic Bight, an increase in the western Gulf of Mexico, and non-significant response for the remaining area. Such spatial pattern is also consistent with previous projections of sea surface winds and ocean wave heights.
文摘本文基于FVCOM(Finite Volume Community Ocean Model)构建了一个覆盖中国渤海、黄海和东海的数值模型,采用NCEP-CFSR风场数据对1509号台风“灿鸿”产生的风暴潮进行模拟,与实测水位数据的对比表明该模型可靠、模拟结果合理。基于此模型,本文对非线性作用和地形在风暴潮增水过程中的作用进行了研究。首先,重点分析了增水过程中潮汐与风暴潮的非线性作用,结果表明:高潮时非线性作用使增水值降低;低潮时非线性作用使增水值升高。另外,开边界处分别只添加M2、S2和K1分潮,分析天文潮的潮高和周期对非线性作用的影响,结果表明:潮高越高,非线性作用越明显;半日潮的非线性作用较全日潮更明显;并且,增水极值附近出现的半日周期的波动也与非线性作用有关。其次,除了非线性作用,地形对风暴潮的增水也有一定影响,本文改变地形的实验结果表明:坡度越大,增水极值越小。琉球群岛的存在使得东南沿海出现风暴潮增水的面积减小,但使得风暴潮增水的高值区域扩大。
基金The National Programme on Global Change and Air-Sea Interaction of China under contract Nos GASI-GEOGE-03,GASI-04-01-02 and GASI-GEOGE-05the National Natural Science Foundation of China under contract Nos 41476047,41106045,41506012 and 41206045
文摘A multi-index analysis including grain size, major and trace elements is performed on the surface sediments from the northeastern Beibu Gulf to trace the sources of the sediments and to understand the controlling factors for elements distribution. The mean grain size exhibits a wide variation ranging from 0.09Φ to 8.05Φ with an average value of 5.33Φ. The average contents of major elements descend in an order of c(SiO_2)>c(Al_2O_3)>c(Fe_2O_3)>c(CaO)>c(MgO)>c(K_2O)>c(Na_2O)>c(TiO_2)>c(P_2O_5)>c(MnO), while those of trace elements exhibit a descending order of c(Sr)>c(Rb)>c(V)>c(Zn)>c(Cr)>c(Pb)>c(Ni)>c(Cu)>c(As). On the basis of elementary distribution characteristics and statistical analyses, the study area is divided into the four zones: Zone I is located in the northeastern coastal area of the gulf, which receives large amount of fluvial materials from local rivers in Guangxi and Guangdong, China, and the Qiongzhou Strait; Zone Ⅱ is located in the center of the study area, where surface sediments exhibits a multiple source; Zone Ⅲ is located in the Qiongzhou Strait, where surface sediments are dominated by materials from the Zhujiang River and Hainan; Zone IV is located in the southwest of the study area, where surface sediments are mainly originated from the Red River and Hainan. The statistical analyses of sediment geochemical characteristics reveal that the grain size, which is mainly influenced by hydrodynamics and mineral composition of terrigenous materials, is the leading factor controlling the elementary distribution.Meanwhile, impacts from anthropogenic activities and marine biogenic process will also be taken into consideration.
基金The Louisiana Board of Regents EPSCoR(pFund)the Louisiana Board of Regents Traditional Enhancement Program under contract No.LEQSF(2016-17)-ENH-TR-05+1 种基金the North Pacific Research Board under contract No.1229the Louisiana Department of Wildlife and Fisheries under contract No.699775/514-100210
文摘The generation of high-resolution data is increasingly important in understanding the complexities of coastal ocean and developing sound management strategies, especially in view of the long-term impact of severe weather systems. The impact of severe weather systems, when integrated over time, can be significant when compared with tidal oscillations. This paper presents a study of water transport out of Vermilion Bay in response to a short, intense event associated with a passing atmospheric cold front, and reports the application of an Acoustic Doppler Current Profiler (ADCP) mounted on an Automated Surface Craft (ASC), known as the auto-boat or unmanned boat, developed in our lab at the Louisiana State University, to generate high resolution data accurately at a fraction of the cost of a manned boat. In our study, we used a manned boat and an unmanned boat, each for over 24 h to cover an entire diurnal tidal cycle, to measure flow velocity profiles to calculate the total transport. A stationary ADCP was deployed in the Southwest Pass of the Vermilion Bay from May 2009 to April 2012, providing data almost continuously (with only one major gap), with a 717-day record of water transport between the northern Gulf of Mexico and Vermilion Bay, and demonstrates the importance of the pass in water transport.
基金supported by the National Programme on Global Change and Air-Sea Interaction(Nos.GASI-GEOGE-03 and GASI-GEOGE-06-02)the National Natural Science Foundation of China(Nos.41476047,41106045,41506012 and 41206045)the School of Geographic and Oceanographic Sciences,Nanjing University,China,State Key Laboratory of Marine Geology,Tongji University,China and Beta Analytic Inc.,USA for their technical assistance in the laboratory
文摘The relationship between the East Asian winter monsoon(EAWM) and East Asian summer monsoon(EASM) during the Holocene is complicated and remains controversial.In this study,analysis of grain size and benthic foraminiferal oxygen isotope,as well as accelerator mass spectrometry ^(14)C dating was performed on a sediment core retrieved from the newly revealed muddy deposit on the northern South China Sea continental shelf.The history of the EAWM and EASM were reconstructed for the last 8200 a BP.Further analysis in conjunction with previously published paleo-climate proxies revealed that the relationship between the EAWM and EASM during the Holocene is more complex than a simple and strict anti-phase one-both negative and positive correlations were identified.The EAWM and EASM are negatively correlated around 7500,4800,4200,3200,and 300 a BP(cooling periods),while positively correlated around 7100,3700,and 2100 a BP(warm periods).In particular,both the EAWM and EASM intensified during the three positive correlation periods.However,we also found that the relationship between these two sub-monsoons is anti-phase during the final phase of particularly hot periods like Holocene Optimum and Medieval warm period.The possible impact from variations of solar irradiance on the relationship between the EAWM and EASM was also discussed.
基金supported by the National Natural Science Foundation of China (Nos. 41476047, 41106045, 41506064 and 41427803)the National Programme on Global Change and Air-Sea Interaction (Nos. GASIGEOGE-03 and GASI-04-01-02)
文摘A coupled approach based on grain size and geochemical elements is used to trace the provenance of surface sediments and to confirm the distribution patterns of grain size and elements on the continental shelf off western Guangdong Province and northeastern Hainan Island. The mean grain size ranges from 0.05 φ to 7.28 φ with a mean value of 5.60 φ. The average concentra- tions of major elements descend in the order of SiO2 > Al2O3 > CaO > Fe2O3 > K2O > MgO > Na2O > TiO2 > P2O5 > MnO, while those of trace elements exhibit a descending order of Sr > Rb > Zn > V > Cr > Pb > Ni > Cu > As > Cd. On the basis of the distribution patterns of elements and results of statistical analysis, the study area is classified into three zones. Zone I locates on the continental shelf off western Guangdong Province, and the sediments are mainly from Pearl River, Taiwan Residents rivers, and small rivers nearby. Zone II locates in the eastern exit of Qiongzhou Strait and the coastal area off Leizhou Peninsula, and the sediments are mainly from the ero- sion products of Qiongzhou Strait and Hainan Island. Zone III locates off the eastern Hainan Island and the continental shelf deeper than 50 m isobaths, and the sediments are mainly from Hainan Island and coral reef. The influence from open water should also be considered. Results indicate that the grain size is the main controlling factor for major and trace element contents and that anthropo- genic impact and biological activity also play an important role in the distribution of these elements.
基金supported by the National Key Research and Development Program of China (2016YFE0133700)the National Natural Science Foundation of China (42106167 and42076170)。
文摘Densely populated coasts are vulnerable to storm damage. Episodic storm-induced redistribution of coastal sediment is known to have major geological and ecological implications [1,2], but little is known about storm-driven delta erosion and longshore sediment transport. The Yangtze (Changjiang) Delta and Zhejiang–Fujian coasts (Fig. S1 online) are among the world’s largest coastal depositional systems, and play an important role in supporting China’s socioeconomic development [3,4].
基金support provided by the National Natural Science Foundation of China(42192562)the 2020 Training Program for Excellent Young Research Talents Fund from Guangdong Ocean Universities(156-2019-XMZC-0012-02-0124)the Postgraduate Education Innovation Project of Guangdong Ocean University(521005041).
文摘There is the current lack of comprehensive understanding of the hotspots,frequency,duration,spatiotemporal trends,and physical drivers of marine heatwaves(MHWs)within the Gulf of Mexico(GoM).Here,a series of high-resolution satellite and reanalysis products are used to examine their spatiotemporal characteristics,trends,and possible geophysical triggers of MHWs.Possible impacts of the MHW on coral reefs are also discussed.Results reveal an increasing trend in their frequency,duration,and intensities from 1983–2021,particularly after 2016.It identifies MHWs hotspots within the GoM,notably the northern and western shelves and the Loop Current.The study further documents an intense MHW event from late 2020 to early 2021 near the Yucatan Channel,south of 24°N,attributing its development to oceanic processes such as wind anomalies,anticyclonic eddies,and current-driven heat transport anomalies.The occurrence of this MHW event potentially increased thermal stress on the Campeche and Tuxtlas Reef Systems.This research illuminates the increasing trends and impacts of MHWs in the GoM,providing valuable insights for understanding and predicting the effects of climate change on marine ecosystems.
基金the National Natural Science Foundation of China (Grant Nos. 40725011 and U0733003)the Hundred Talents Program of the Chinese Academy of Sciences (CAS) and the Foundation of Key Laboratory of Marginal Sea Geology of CAS (Grant No. MSGL07-21)
文摘Seep carbonates were collected from the Alaminos Canyon lease area, Gulf of Mexico. The carbonates are present as slabs and blocks. Bivalve shell and foraminifer are the dominant bioclasts in carbonate. Pores are common and usually filled with acicular aragonite crystals. XRD investigation shows that aragonite is the dominate mineral (98%). Peloids, clotted microfabirc and botryoidal aragonite are de-veloped in carbonate and suggest a genesis linked with bacterial degradation of the hydrocarbons. The δ13C value of bioclasts in carbonate is from-4.9‰ to-0.6‰, indicating that the carbon source is mainly from sea water as well as the small portion incorporation of the seep hydrocarbon. The microcrystalline and sparite aragonite shows the δ13C value from-31.3‰ to-23.4‰, suggesting that their carbon is derived mainly from microbial degradation of crude oil. 14C analyses give the radiocarbon age of about 10 ka. Rare earth elements (REE) analyses of the 5% HNO3-treated solution of the carbonates show that the total REE content of the carbonates is low, that is from 0.752 to 12.725 μg·g-1. The shale-normalized REE patterns show significantly negative Ce anomalies. This suggests that cold seep carbonate is most likely formed in a relatively aerobic environment.
基金supported by the National Basic Research Program of China (Grant No.2009CB219508)National Natural Science Foundation of China (Grant Nos.40725011 and U0733003)+1 种基金the State Key Laboratory of Organic Geochemistry (Grant No.OGL-200811)Knowledge Innovation Program of Chinese Academy of Sciences (Grant No.KGCX2-YW-805)
文摘Here we reported the fatty-acids and their δ13 C values in seep carbonates collected from Green Canyon lease block 185 (GC 185;Sample GC-F) at upper continental slope (water depth:~540 m),and Alaminos Canyon lease block 645 (GC 645;Sample AC-E) at lower continental slope (water depth:~2200 m) of the Gulf of Mexico.More than thirty kinds of fatty acids were detected in both samples.These fatty acids are maximized at C 16.There is a clear even-over-odd carbon number predominance in carbon number range.The fatty acids are mainly composed of n-fatty acids,iso-/anteiso-fatty acids and terminally branched odd-numbered fatty acids (iso/anteiso).The low δ13 C values (-39.99‰ to -32.36‰) of n-C 12:0,n-C 13:0,i-C 14:0 and n-C 14:0 suggest that they may relate to the chemosynthetic communities at seep sites.The unsaturated fatty acids n-C 18:2 and C 18:1 △9 have the same δ13 C values,they may originate from the Beggiatoa/Thioploca.Unlike other fatty acids,the terminally branched fatty acids (iso/anteiso) show lower δ13 C values (as low as -63.95‰) suggesting a possible relationship to sulfate reducing bacteria,which is common during anaerobic oxidation of methane at seep sites.