An ocean carbon cycle model driven by a constant flow field produced by a two-dimensional thermohaline circulation model is developed. Assuming that the biogenic carbon in the oceans is in a dynamic equilibrium, the i...An ocean carbon cycle model driven by a constant flow field produced by a two-dimensional thermohaline circulation model is developed. Assuming that the biogenic carbon in the oceans is in a dynamic equilibrium, the inorganic carbon cycle is investigated. Before the oceanic uptake of CO_2 is carried out, the investigation of 14C distributions in the oceans, including natural and bomb-produced 14C,is conducted by using different values of the exchange coefficient of CO_2for different flow fields (different vertical diffusivities) to test the performance of the model. The suitable values of the exchange coefficient and vertical diffusivities are chosen for the carbon cycle model. Under the forcing of given preindustrial atmospheric CO_2 concentration of 280 ppmv, the carbon cycle model is integrated for seven thousand years to reach a steady state. For the human perturbation, two methods including the prescribed atmospheric pCO_2 and prescribed industrial emissions are used in this work. The results from the prescribed atmospheric pCO_2 show that the oceans take up 36% of carbon dioxide released by human activities for the period of 1980-1989, while the results from the prescribed industrial emission rates show that the oceans take up 34% of carbon dioxide emitted by industrial sources for the same period. By using the simple method of subtracting industrial emission rate from the total atmosphere+ocean accumulating rate, it can be deduced that before industrial revolution a non-industrial source exists, while after 1940 an extra sink is needed, and that a total non-industrial source of 45 GtC is obtained for the period of 1790-1990.展开更多
A three-dimensional ocean carbon cycle model which is a general circulation model coupled with simple biogeochemical processes is used to simulate CO_2 uptake by the ocean.The OGCM used is a modified version of the Ge...A three-dimensional ocean carbon cycle model which is a general circulation model coupled with simple biogeochemical processes is used to simulate CO_2 uptake by the ocean.The OGCM used is a modified version of the Geophysical Fluid Dynamics Laboratory modular ocean model (MOM2).The ocean chemistry and a simple ocean biota model are included.Principal variables are total CO_2,alkalinity and phosphate.The vertical profile of POC flux observed by sediment traps is adopted,the rain ratio,a ratio of production rate of calcite against that of POC,and the bio-production efficiency should be 0.06 and 2 per year,separately.The uptake of anthropogenic CO_2 by the ocean is studied.Calculated oceanic uptake of anthropogenic CO_2 during the 1980s is 2.05×10~(15)g(Pg)per year.The regional distributions of global oceanic CO_2 are discussed.展开更多
How coral reefs with high productivity and biodiversity can flourish in oligotrophic tropical oceans has inspired substantial research on coral reef ecosystems.Increasing evidence shows that similar to water in an oas...How coral reefs with high productivity and biodiversity can flourish in oligotrophic tropical oceans has inspired substantial research on coral reef ecosystems.Increasing evidence shows that similar to water in an oasis in the desert,there are stable nutrient supplies to coral reefs in oligotrophic oceans.Here,with emphasis on the fluxes of organic matter,we summarize at the ecosystem level(1)the multiple input pathways of external nutrients,(2)the storage of nutrients in reef organisms,(3)the efficient retaining and recycling of dissolved and particulate organic matter within coral reef ecosystems,(4)the distinctly high phytoplankton productivity and biomass inside and near oceanic coral reefs,and(5)the export of reef-related organic carbon to adjacent open oceans.These properties enable coral reefs to function as ecological“pumps”for gathering nutrients across ecosystems and space,retaining and recycling nutrients within the ecosystem,supporting high phytoplankton productivity,and exporting organic carbon to adjacent open oceans.Particularly,the high phytoplankton productivity and biomass make waters around coral reefs potential hotspots of carbon export to ocean depths via the biological pump.We demonstrate that organic carbon influx is vital for coral reef ecosystems’carbon budget and carbon export.The concept of the coral reef ecological pump provides a framework to improve the understanding of the functioning of the coral reef ecosystem and its responses to disturbance.Prospects of the coral reef ecological pump in coral reef studies are discussed in changing oceans driven by human activities and global change in the Anthropocene.展开更多
A global ocean carbon cycle model based on the ocean general circulation model POP and the improved biogeochemical model OCMIP-2 is employed to simulate carbon cycle processes under the historically observed atmospher...A global ocean carbon cycle model based on the ocean general circulation model POP and the improved biogeochemical model OCMIP-2 is employed to simulate carbon cycle processes under the historically observed atmospheric CO 2 concentration and different future scenarios (called Rep- resentative Concentration Pathways, or RCPs). The RCPs in this paper follow the design of Inter- governmental Panel on Climate Change (IPCC) for the Fifth Assessment Report (AR5). The model results show that the ocean absorbs CO 2 from atmosphere and the absorbability will continue in the 21st century under the four RCPs. The net air-sea CO 2 flux increased during the historical time and reached 1.87 Pg/a (calculated by carbon) in 2005; however, it would reach peak and then decrease in the 21st century. The ocean absorbs CO 2 mainly in the mid latitude, and releases CO 2 in the equator area. However, in the Antarctic Circumpolar Current (ACC) area the ocean would change from source to sink under the rising CO 2 concentration, including RCP4.5, RCP6.0, and RCP8.5. In 2100, the anthropogenic carbon would be transported to the 40 S in the Atlantic Ocean by the North Atlantic Deep Water (NADW), and also be transported to the north by the Antarctic Bottom Water (AABW) along the Antarctic continent in the Atlantic and Pacific oceans. The ocean pH value is also simulated by the model. The pH decreased by 0.1 after the industrial revolution, and would continue to decrease in the 21st century. For the highest concentration sce- nario of RCP8.5, the global averaged pH would decrease by 0.43 to reach 7.73 due to the absorption of CO 2 from atmosphere.展开更多
A decrease in atmospheric CO_(2)partial pressure(pCO_(2))is considered an important prerequisite for the onset and intensification of Northern Hemisphere Glaciation(NHG).However,how the ocean sequestered missing CO_(2...A decrease in atmospheric CO_(2)partial pressure(pCO_(2))is considered an important prerequisite for the onset and intensification of Northern Hemisphere Glaciation(NHG).However,how the ocean sequestered missing CO_(2)during the NHG is still uncertain.Changes in surface productivity and deep ventilation in the Southern Ocean(SO)have been proposed to explain the variations in atmospheric pCO_(2)over the last eight glacial cycles,but it is unclear whether these mechanisms contributed to the decrease in atmospheric pCO_(2)during the NHG.Using titanium-normalized contents and mass accumulation rates of biogenic opal and total organic carbon from the International Ocean Discovery Program(IODP)Expedition 374 Site U1524A,we reconstruct the productivity in the Ross Sea,Antarctica,from 3.3 Ma to 2.4 Ma.The productivity records exhibit a long-term decreasing trend and several distinct phased evolutionary features.Specifically,the local productivity fluctuated dramatically during 3.3-3.0 Ma,decreased gradually during 3.0-2.6 Ma,and remained relatively constant during 2.6-2.4 Ma.By comparing productivity with its potential influences,we infer that the phased and long-term evolutions of productivity were mainly controlled by changes in deep ocean ventilation.Sea ice expansion might have decreased productivity during 3.3-3.0 Ma by light attenuation.Changes in eolian dust input have little effect on productivity.Further analysis revealed no coupling linkage between productivity and atmospheric pCO_(2),indicating that the productivity in the SO Antarctic Zone(AZ)was not the main factor controlling the atmospheric CO_(2)decrease during the NHG.To improve our understanding of the role of SO processes in the NHG,further studies should focus on the potential influences of deep ocean ventilation on atmospheric pCO_(2)in the AZ,and similar studies should also be extended to the sea area in the Subantarctic Zone.展开更多
The climate variability induced by the El Nino-Southern Oscillation(ENSO)cycle drives significant changes in the physical state of the tropical Western Pacific,which has important impacts on the upper ocean carbon cyc...The climate variability induced by the El Nino-Southern Oscillation(ENSO)cycle drives significant changes in the physical state of the tropical Western Pacific,which has important impacts on the upper ocean carbon cycle.During 2015-2016,a super El Nino event occurred in the equatorial Pacific.Suspended particulate matter(SPM)data and related environmental observations in the tropical Western Pacific were obtained during two cruses in Dec.2014 and 2015,which coincided with the early and peak stages of this super El Nino event.Compared with the marine environments in the tropical Western Pacific in Dec.2014,an obviously enhanced upwelling occurred in the Mindanao Dome region;the nitrate concentration in the euphotic zone almo st tripled;and the size,mass concentration,and volume concentration of SPM obviously increased in Dec.2015.The enhanced upwelling in the Mindanao Dome region carried cold but eutrophic water upward from the deep ocean to shallow depths,even into the euphotic zone,which disrupted the previously N-limited conditions and induced a remarkable increase in phytoplankton blooms in the euphotic zone.The se results reveal the mechanism of how nutrient-limited ecosystems in the tropical Western Pacific respond to super El Nino events.In the context of the ENSO cycle,if predicted changes in biogenic particles occur,the proportion of carbon storage in the tropical Western Pacific is estimated to be increased by more than 52%,ultimately affecting the regional and possibly even global carbon cycle.This paper highlights the prospect for long-term prediction of the impact of a super El Nino event on the global carbon cycle and has profound implications for understanding El Nino events.展开更多
Neogloboquadrina pachyderma(sinistral), the dominant planktonic foraminiferal species in the mid-to-high latitude oceans, represents a major component of local calcium carbonate(CaCO) production. However, the predomin...Neogloboquadrina pachyderma(sinistral), the dominant planktonic foraminiferal species in the mid-to-high latitude oceans, represents a major component of local calcium carbonate(CaCO) production. However, the predominant factors,governing the calcification of this species and its potential response to the future marine environmental changes, are poorly understood. The present study utilized an improved cleaning method for the size-normalized weight(SNW) measurement to estimate the SNW of N. pachyderma(sin.) in surface sediments from the Amundsen Sea, the Ross Sea, and the Prydz Bay in the Antarctic Zone of the Southern Ocean. It was found that SNW of N. pachyderma(sin.) is not controlled by deep-water carbonate dissolution post-mortem, and can be therefore, used to reflect the degree of calcification. The comparison between N. pachyderma(sin.) SNW and environmental parameters(temperature, salinity, nutrient concentration, and carbonate system) in the calcification depth revealed that N. pachyderma(sin.) SNWs in the size ranges of 200–250, 250–300, and 300–355 μm are significantly and positively correlated with seawater temperature. Moreover, SNW would increase by ~30% per degree increase in temperature, thereby suggesting that the calcification of N. pachyderma(sin.) in the modern Antarctic Zone of the Southern Ocean is mainly controlled by temperature, rather than by other environmental parameters such as ocean acidification. Importantly, a potential increase in calcification of N. pachyderma(sin.) in the Antarctic Zone to produce CaCOwill release COinto the atmosphere. In turn, the future ocean warming will weaken the ocean carbon sink, thereby generating positive feedback for global warming.展开更多
Humic-like dissolved organic matter(DOM),usually regarded as refractory,is a major component of DOM in marine sediment pore waters.However,its bio-reactivity remains poorly explored in natural environments,which makes...Humic-like dissolved organic matter(DOM),usually regarded as refractory,is a major component of DOM in marine sediment pore waters.However,its bio-reactivity remains poorly explored in natural environments,which makes its roles in supporting subsurface microbial communities and regulating long-term carbon cycling elusive.Here,the bio-reactivity of humiclike DOM was evaluated by modeled reaction rates together with its interactions with microbial communities in five sediment cores collected from the eutrophic Pearl River Estuary to the oligotrophic deep-sea basin in the northern South China Sea.We revealed contrasting relationships between humic-like DOM and microbes in the coastal and deep-sea sediments.In eutrophic coastal sediments,specific microbial groups enriched in the deep layers co-varied with humic-like DOM,while most microbial groups were significantly correlated with protein-like DOM,microbial transformation of which likely resulted in the production of humic-like DOM.On the contrary,in energy-limiting deep-sea sediments,over 70%of the microbial groups were found closely correlated with humic-like DOM,a net consumption of which was demonstrated in deep layers.The consumption of humic-like DOM in deep-sea sediments reduced its total production flux in the uppermost~5-meter layer to about one-tenth of that in coastal sediments,which could consequently decrease the refractory DOM flux to the overlying seawater and influence long-term oceanic carbon cycling.展开更多
文摘An ocean carbon cycle model driven by a constant flow field produced by a two-dimensional thermohaline circulation model is developed. Assuming that the biogenic carbon in the oceans is in a dynamic equilibrium, the inorganic carbon cycle is investigated. Before the oceanic uptake of CO_2 is carried out, the investigation of 14C distributions in the oceans, including natural and bomb-produced 14C,is conducted by using different values of the exchange coefficient of CO_2for different flow fields (different vertical diffusivities) to test the performance of the model. The suitable values of the exchange coefficient and vertical diffusivities are chosen for the carbon cycle model. Under the forcing of given preindustrial atmospheric CO_2 concentration of 280 ppmv, the carbon cycle model is integrated for seven thousand years to reach a steady state. For the human perturbation, two methods including the prescribed atmospheric pCO_2 and prescribed industrial emissions are used in this work. The results from the prescribed atmospheric pCO_2 show that the oceans take up 36% of carbon dioxide released by human activities for the period of 1980-1989, while the results from the prescribed industrial emission rates show that the oceans take up 34% of carbon dioxide emitted by industrial sources for the same period. By using the simple method of subtracting industrial emission rate from the total atmosphere+ocean accumulating rate, it can be deduced that before industrial revolution a non-industrial source exists, while after 1940 an extra sink is needed, and that a total non-industrial source of 45 GtC is obtained for the period of 1790-1990.
基金国家自然科学基金,the National Key Program-Studies of Short-Range Climate Prediction System in China
文摘A three-dimensional ocean carbon cycle model which is a general circulation model coupled with simple biogeochemical processes is used to simulate CO_2 uptake by the ocean.The OGCM used is a modified version of the Geophysical Fluid Dynamics Laboratory modular ocean model (MOM2).The ocean chemistry and a simple ocean biota model are included.Principal variables are total CO_2,alkalinity and phosphate.The vertical profile of POC flux observed by sediment traps is adopted,the rain ratio,a ratio of production rate of calcite against that of POC,and the bio-production efficiency should be 0.06 and 2 per year,separately.The uptake of anthropogenic CO_2 by the ocean is studied.Calculated oceanic uptake of anthropogenic CO_2 during the 1980s is 2.05×10~(15)g(Pg)per year.The regional distributions of global oceanic CO_2 are discussed.
基金The Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) under contract No.GML2019ZD0405the National Natural Science Foundation of China under contract Nos41506150 and 41130855+3 种基金the Guangdong Basic and Applied Basic Research Foundation under contract No.2019A1515011645the National Science and Technology Basic Work Program of the Ministry of Science and Technology of China under contract No.2015FY110600the Science and Technology Planning Project of Guangdong Province,China under contract No.2020B1212060058the Development Fund of South China Sea Institute of Oceanology of the Chinese Academy of Sciences under contract No.SCSIO202204。
文摘How coral reefs with high productivity and biodiversity can flourish in oligotrophic tropical oceans has inspired substantial research on coral reef ecosystems.Increasing evidence shows that similar to water in an oasis in the desert,there are stable nutrient supplies to coral reefs in oligotrophic oceans.Here,with emphasis on the fluxes of organic matter,we summarize at the ecosystem level(1)the multiple input pathways of external nutrients,(2)the storage of nutrients in reef organisms,(3)the efficient retaining and recycling of dissolved and particulate organic matter within coral reef ecosystems,(4)the distinctly high phytoplankton productivity and biomass inside and near oceanic coral reefs,and(5)the export of reef-related organic carbon to adjacent open oceans.These properties enable coral reefs to function as ecological“pumps”for gathering nutrients across ecosystems and space,retaining and recycling nutrients within the ecosystem,supporting high phytoplankton productivity,and exporting organic carbon to adjacent open oceans.Particularly,the high phytoplankton productivity and biomass make waters around coral reefs potential hotspots of carbon export to ocean depths via the biological pump.We demonstrate that organic carbon influx is vital for coral reef ecosystems’carbon budget and carbon export.The concept of the coral reef ecological pump provides a framework to improve the understanding of the functioning of the coral reef ecosystem and its responses to disturbance.Prospects of the coral reef ecological pump in coral reef studies are discussed in changing oceans driven by human activities and global change in the Anthropocene.
基金The 973 Project under contract Nos 2010CB950300 and 2010CB950500the Key Project of the National Natural Science Foundation of China under contract No. 40730842+1 种基金the Public Science and Technology Research Funds projects of ocean under contract No. 201105019the International Cooperation Project of Ministry of Science and Technology of China under contract No. S2011GR0348
文摘A global ocean carbon cycle model based on the ocean general circulation model POP and the improved biogeochemical model OCMIP-2 is employed to simulate carbon cycle processes under the historically observed atmospheric CO 2 concentration and different future scenarios (called Rep- resentative Concentration Pathways, or RCPs). The RCPs in this paper follow the design of Inter- governmental Panel on Climate Change (IPCC) for the Fifth Assessment Report (AR5). The model results show that the ocean absorbs CO 2 from atmosphere and the absorbability will continue in the 21st century under the four RCPs. The net air-sea CO 2 flux increased during the historical time and reached 1.87 Pg/a (calculated by carbon) in 2005; however, it would reach peak and then decrease in the 21st century. The ocean absorbs CO 2 mainly in the mid latitude, and releases CO 2 in the equator area. However, in the Antarctic Circumpolar Current (ACC) area the ocean would change from source to sink under the rising CO 2 concentration, including RCP4.5, RCP6.0, and RCP8.5. In 2100, the anthropogenic carbon would be transported to the 40 S in the Atlantic Ocean by the North Atlantic Deep Water (NADW), and also be transported to the north by the Antarctic Bottom Water (AABW) along the Antarctic continent in the Atlantic and Pacific oceans. The ocean pH value is also simulated by the model. The pH decreased by 0.1 after the industrial revolution, and would continue to decrease in the 21st century. For the highest concentration sce- nario of RCP8.5, the global averaged pH would decrease by 0.43 to reach 7.73 due to the absorption of CO 2 from atmosphere.
基金supported by the National Natural Science Foundation of China(Grant Nos.42076232&42006075)the Impact and Response of Antarctic Seas to Climate Change Program(Grant No.IRASCC2020-2022-No.01-03-02)the Taishan Scholars Projects Funding(Grant Nos.TS20190963&TSQN202211265)。
文摘A decrease in atmospheric CO_(2)partial pressure(pCO_(2))is considered an important prerequisite for the onset and intensification of Northern Hemisphere Glaciation(NHG).However,how the ocean sequestered missing CO_(2)during the NHG is still uncertain.Changes in surface productivity and deep ventilation in the Southern Ocean(SO)have been proposed to explain the variations in atmospheric pCO_(2)over the last eight glacial cycles,but it is unclear whether these mechanisms contributed to the decrease in atmospheric pCO_(2)during the NHG.Using titanium-normalized contents and mass accumulation rates of biogenic opal and total organic carbon from the International Ocean Discovery Program(IODP)Expedition 374 Site U1524A,we reconstruct the productivity in the Ross Sea,Antarctica,from 3.3 Ma to 2.4 Ma.The productivity records exhibit a long-term decreasing trend and several distinct phased evolutionary features.Specifically,the local productivity fluctuated dramatically during 3.3-3.0 Ma,decreased gradually during 3.0-2.6 Ma,and remained relatively constant during 2.6-2.4 Ma.By comparing productivity with its potential influences,we infer that the phased and long-term evolutions of productivity were mainly controlled by changes in deep ocean ventilation.Sea ice expansion might have decreased productivity during 3.3-3.0 Ma by light attenuation.Changes in eolian dust input have little effect on productivity.Further analysis revealed no coupling linkage between productivity and atmospheric pCO_(2),indicating that the productivity in the SO Antarctic Zone(AZ)was not the main factor controlling the atmospheric CO_(2)decrease during the NHG.To improve our understanding of the role of SO processes in the NHG,further studies should focus on the potential influences of deep ocean ventilation on atmospheric pCO_(2)in the AZ,and similar studies should also be extended to the sea area in the Subantarctic Zone.
基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Nos.XDB42010203,XDA19060401,XDA23050503)the Science&Technology Basic Resources Investigation Program of China(No.2017FY100802)+1 种基金the Open Fund for Key Laboratory of Mar.Geol.and Environment,Institute of Oceanology,Chinese Academy of Sciences(No.MGE2019KG03)the Qingdao(Laoshan)Postdoctoral Applied Research Proj ect in 2019(No.Y9KY161)。
文摘The climate variability induced by the El Nino-Southern Oscillation(ENSO)cycle drives significant changes in the physical state of the tropical Western Pacific,which has important impacts on the upper ocean carbon cycle.During 2015-2016,a super El Nino event occurred in the equatorial Pacific.Suspended particulate matter(SPM)data and related environmental observations in the tropical Western Pacific were obtained during two cruses in Dec.2014 and 2015,which coincided with the early and peak stages of this super El Nino event.Compared with the marine environments in the tropical Western Pacific in Dec.2014,an obviously enhanced upwelling occurred in the Mindanao Dome region;the nitrate concentration in the euphotic zone almo st tripled;and the size,mass concentration,and volume concentration of SPM obviously increased in Dec.2015.The enhanced upwelling in the Mindanao Dome region carried cold but eutrophic water upward from the deep ocean to shallow depths,even into the euphotic zone,which disrupted the previously N-limited conditions and induced a remarkable increase in phytoplankton blooms in the euphotic zone.The se results reveal the mechanism of how nutrient-limited ecosystems in the tropical Western Pacific respond to super El Nino events.In the context of the ENSO cycle,if predicted changes in biogenic particles occur,the proportion of carbon storage in the tropical Western Pacific is estimated to be increased by more than 52%,ultimately affecting the regional and possibly even global carbon cycle.This paper highlights the prospect for long-term prediction of the impact of a super El Nino event on the global carbon cycle and has profound implications for understanding El Nino events.
基金the support of Chinese Arctic and Antarctic Administrationsupported by the Impact and Response of Antarctic Seas to Climate Change (Grant No. IRASCC2020-2022-No.01-03-02)+2 种基金the Basic Scientific Fund for National Public Research Institutes of China (Grant Nos. 2019S04, 2017Y07, 2019Q09)the National Natural Science Foundation of China (Grant Nos. 42076232, 41976080, 42006075)the Taishan Scholars Project Funding (Grant No. TS20190963)。
文摘Neogloboquadrina pachyderma(sinistral), the dominant planktonic foraminiferal species in the mid-to-high latitude oceans, represents a major component of local calcium carbonate(CaCO) production. However, the predominant factors,governing the calcification of this species and its potential response to the future marine environmental changes, are poorly understood. The present study utilized an improved cleaning method for the size-normalized weight(SNW) measurement to estimate the SNW of N. pachyderma(sin.) in surface sediments from the Amundsen Sea, the Ross Sea, and the Prydz Bay in the Antarctic Zone of the Southern Ocean. It was found that SNW of N. pachyderma(sin.) is not controlled by deep-water carbonate dissolution post-mortem, and can be therefore, used to reflect the degree of calcification. The comparison between N. pachyderma(sin.) SNW and environmental parameters(temperature, salinity, nutrient concentration, and carbonate system) in the calcification depth revealed that N. pachyderma(sin.) SNWs in the size ranges of 200–250, 250–300, and 300–355 μm are significantly and positively correlated with seawater temperature. Moreover, SNW would increase by ~30% per degree increase in temperature, thereby suggesting that the calcification of N. pachyderma(sin.) in the modern Antarctic Zone of the Southern Ocean is mainly controlled by temperature, rather than by other environmental parameters such as ocean acidification. Importantly, a potential increase in calcification of N. pachyderma(sin.) in the Antarctic Zone to produce CaCOwill release COinto the atmosphere. In turn, the future ocean warming will weaken the ocean carbon sink, thereby generating positive feedback for global warming.
基金supported by the National Natural Science Foundation of China(Grant Nos.42141003,41921006&41867057)the National Key Research and Development Program of China(Grant No.2020YFA0608300)+4 种基金the“Shanghai Jiao Tong University 2030”Program(Grant No.WH510244001)partially by the Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(Grant No.SMSEGL20SC01)the Center for Ocean Research in Hong Kong and Macao(CORECORE is a joint research center for ocean research between QNLM and HKUST)The SO269 cruise(SOCLIS-South China Sea-natural Laboratory under climatic and human induced stress,BMBF FKZ 03G0269)was a contribution to the bilateral Sino-German project MEGAPOL-Megacity’s fingerprint in Chinese marginal seas:Investigation of pollutant fingerprints and dispersal within the framework of WTZ China of the German government and was founded by BMBF(Grant No.03F0786A)。
文摘Humic-like dissolved organic matter(DOM),usually regarded as refractory,is a major component of DOM in marine sediment pore waters.However,its bio-reactivity remains poorly explored in natural environments,which makes its roles in supporting subsurface microbial communities and regulating long-term carbon cycling elusive.Here,the bio-reactivity of humiclike DOM was evaluated by modeled reaction rates together with its interactions with microbial communities in five sediment cores collected from the eutrophic Pearl River Estuary to the oligotrophic deep-sea basin in the northern South China Sea.We revealed contrasting relationships between humic-like DOM and microbes in the coastal and deep-sea sediments.In eutrophic coastal sediments,specific microbial groups enriched in the deep layers co-varied with humic-like DOM,while most microbial groups were significantly correlated with protein-like DOM,microbial transformation of which likely resulted in the production of humic-like DOM.On the contrary,in energy-limiting deep-sea sediments,over 70%of the microbial groups were found closely correlated with humic-like DOM,a net consumption of which was demonstrated in deep layers.The consumption of humic-like DOM in deep-sea sediments reduced its total production flux in the uppermost~5-meter layer to about one-tenth of that in coastal sediments,which could consequently decrease the refractory DOM flux to the overlying seawater and influence long-term oceanic carbon cycling.