Coccolithophorid is unicellular marine microalgae with a global distribution in temperate and sub-temperate oceanic regions and has the ability to produce ＇the coccoliths＇. It is considered to be the second most pro...Coccolithophorid is unicellular marine microalgae with a global distribution in temperate and sub-temperate oceanic regions and has the ability to produce ＇the coccoliths＇. It is considered to be the second most productive calcifying organism on earth and becoming an important factor in the global carbonate cycle. Emiliania huxleyi is one of the only two bloom-forming coccolithophores and becomes a species crucial to the study of global biogeochemical cycles and climate modeling. Coccolithoviruse is a recently discovered group of viruses infecting the marine coceolithophorid E. huxleyi. They are a major cause of coceolithophore bloom termination, and DMSP concentration is increasing in the process of viral lysis. Phylogenetic evidences support that some genes are functional both in E. huxleyi and its virus （EhV）. Horizontal gene transfer （HGT） of multiple functionally coupled enzymes occurs in E. huxleyi and its DNA virus EhV has been confirmed, which contributes to the diversification and adaptation of plankton in the oceans and also critically regulates virus-host infection by allowing viruses to control host metabolic pathways for their repli- cation. Therefore, it is of particular interest to understand this host-virus interaction. On this issue, we have made a minireview of coeeolithoviruses focusing on the basic characteristics, phylogenesis, horizontal gene transfer and the interaction between the host and its viruses, as well as its important role in global biogeochemical cycling.展开更多
A coastal upwelling event in the southern Taiwan Strait （STWS） was investigated using intensive cruise surveys （four repeated transects in a month） and satellite data in July and early August 2004. The extensive u...A coastal upwelling event in the southern Taiwan Strait （STWS） was investigated using intensive cruise surveys （four repeated transects in a month） and satellite data in July and early August 2004. The extensive upwelling-associated surface cold water was first observed in early July （-2.0×10a km2） along the STWS coast. Then, the cold surface water reduced in size by -50% with decreased chlorophyll concentrations after 15 days, indicating the weakening of the upwelling event. At the end of July, the cold surface water disappeared. The temporal variations of the surface cold water and the 3-D hydrography around Dongshan Island are thought to be mainly attributed to the weakened upwelling-favorable southwestern wind, the asymmetric spatial structure of the wind field and the intrusion of warm water from the northern South China Sea.展开更多
In this study, two common pollutants (benzo[a]pyrene and methamidophos) in marine environment were tested by comet assay for their inducement of in vivo genotoxic effect to the blood cells of black porgy ( Acanthopagr...In this study, two common pollutants (benzo[a]pyrene and methamidophos) in marine environment were tested by comet assay for their inducement of in vivo genotoxic effect to the blood cells of black porgy ( Acanthopagrus schlegeli). The fish was exposed to 2 μg/L of benzo[a]pyrene (BaP) and methamidophos, and their mixture. The assay was performed on whole blood at 2 h, 5 h, 24 h and 96 h exposure intervals. A signifi- cant increase in DNA damage was observed in each treatment with the pollutants. Additive effect of BaP and methamidophos was also found in the experiment. However, the decrease ratios of DNA damage for 5 h and 96 h exposure interals compared with 2 h and 24 h exposure ones, respectively, were noticed. This phenomenon may be explained by the function of repairing process via enzyme cytochrome P450 in the animal. Evidence of the genotoxicity of organophosphorus pesticides (OPs) and polynuclear aromatic hydrocarbons (PAHs) on marine fish are discussed in this paper.展开更多
Mud crab （Scylla serrata） is an important commercial crustacean in China. An experiment was designed to study the effect of cold stress on S. serrata. After a one-week adaptation at 28℃, the temperature is suddenly...Mud crab （Scylla serrata） is an important commercial crustacean in China. An experiment was designed to study the effect of cold stress on S. serrata. After a one-week adaptation at 28℃, the temperature is suddenly reduced to 4℃. The crabs were sampled every 2 h for 10 h and dissected immediately to measure the enzyme activity. The crabs at room temperature （28℃） were used as the control group. The activity of superoxide dismutase （SOD）, catalase （CAT） and gkttathione peroxidase （GPX）, the content of malondialdehyde （MDA） and the activity of 4 ATPases （Na^＋, K^＋-ATPase, Mg^2＋-ATPase; Ca^2＋-ATPase; Ca^2＋, Mg^2＋-ATPase） were measured biochemically. In contrast to the control group, the SOD activity increased significantly from 2 to 6 h after the cold stress, and then decreased. The CAT and GPX activities increased in 2 h, and then decreased gradually. The content of MDA increased gradually in 4 h. The activity of Na^＋, K^＋-ATPase decreased in 2 h, increased up to the top value at Hour 6, then decreased again. The activities of Mg^2＋-ATPase, Ca^2＋-ATPase and Ca^2＋, Mg^2＋-ATPase increased significantly in 6 h, insignificantly in any other hours. Under cold stress, the activity of antioxidative enzymes in S, serrata was reduced at first then stabilized, ROS-scavenging weakened, and MDA accumulated gradually in the gill after 6 h. The activity of the 4 ATPases in the crab decreased after 6 h, suggesting that the ability to regulate ion concentration has been paralyzed. Therefore, the maximum period to sustain healthy meat in the crab under cold stress is 6 hours.展开更多
Microorganisms play an essential role in the glacier carbon cycle;how they transform organic matter in mountain glacial cryoconite remains to be studied.Here,we applied ultra-high resolution Fourier transform ion cycl...Microorganisms play an essential role in the glacier carbon cycle;how they transform organic matter in mountain glacial cryoconite remains to be studied.Here,we applied ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS)and deep sequencing of 16S rRNA gene,to investigate the temporal microbial transformation of dissolved organic matter(DOM)of the Tibetan Plateau cryoconite.During the 60-day incubation,we found that DOM in cryoconite underwent a three-stage transformation,with decreasing bioavailability over time.The microbial community did not change much in the first week while degrading DOM molecules that were associated with higher H/C_(wa)and lower O/C_(wa).During days 15-30,DOM composition remained stable while microbial diversity increased.By day 60,the DOM was microbially converted into a higher state of recalcitrance,with higher values of aromatic index,O/C_(wa),and lower H/C_(wa),which contained molecules containing more heteroatoms.Cooperation among various microbial taxa,like Cyanobacteria,Bacteroidota,Gammaproteobacteria,Firmicutes,and Actinobacteriota,drove the DOM transformation in cryoconite.This study sheds light on the in-situ transformation of DOM composition meditated by microbial populations in cryoconite at a temporal scale,providing new insights into understanding the microbial roles in the glacier organic carbon transformation.展开更多
The oceans are the largest carbon pools on Earth, and play the role of a "buffer" in climate change. Blue carbon, the carbon(mainly organic carbon) captured by marine ecosystems, is one of the important mech...The oceans are the largest carbon pools on Earth, and play the role of a "buffer" in climate change. Blue carbon, the carbon(mainly organic carbon) captured by marine ecosystems, is one of the important mechanisms of marine carbon storage.Blue carbon was initially recognized only in the form of visible coastal plant carbon sequestration. In fact, microorganisms(phytoplankton, bacteria, archaea, viruses, and protozoa), which did not receive much attention in the past, account for more than 90% of the total marine biomass and are the main contributors to blue carbon. Chinese coastal seas, equivalent to 1/3 of China's total land area, have a huge carbon sink potential needing urgently research and development. In this paper, we focus on the processes and mechanisms of coastal ocean's carbon sequestration and the approaches for increasing that sequestration. We discuss the structures of coastal ecosystems, the processes of carbon cycle, and the mechanisms of carbon sequestration. Using the evolution of coastal ocean's carbon sinks in sedimentary records over geologic times, we also discuss the possible effects of natural processes and anthropogenic activities on marine carbon sinks. Finally, we discuss the prospect of using carbon sequestration engineering for increasing coastal ocean's carbon storage capacity.展开更多
Dissolved organic matter(DOM) in the ocean is one of the largest carbon pools on Earth. Microbial metabolism is an important process that shapes the marine DOM pool. Current studies on the interactions between microor...Dissolved organic matter(DOM) in the ocean is one of the largest carbon pools on Earth. Microbial metabolism is an important process that shapes the marine DOM pool. Current studies on the interactions between microorganisms and DOM focus mainly on oxic environments. Few studies have addressed the molecular characteristics of DOM in microbial-mediated transformation under anoxic/hypoxic conditions. As a result of deteriorating water quality due to eutrophication and global warming, anoxia occurs frequently in coastal waters. In this study, we performed an experiment to investigate changes in microbial community responses and the molecular characteristics of DOM in microbial-mediated transformation under hypoxic conditions. We compared microbial-mediated DOM transformation at different dissolved oxygen levels(7, 5, and 2 mg L^(-1)) and in different media(natural and artificial seawater with and without laminarin). We also investigated differences in DOM composition between groups using spectroscopic analysis and ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry. The results showed decreased microbial metabolic activity and delayed community succession at low oxygen(≤2 mg L^(-1)) in natural seawater supplemented with laminarin. The growth of strictly aerobic bacteria such as Pseudomonadaceae and Sphingomonadaceae was inhibited and the total organic carbon utilization rate was reduced by 36.9–46.7% from 4 to 32days. Moreover, tyrosine-like and tryptophan-like components were preserved, while DOM humification and modified aromaticity indices were significantly reduced under low oxygen conditions. This experiment provides justification for further study of the processes and mechanisms of improved labile DOM preservation in anoxic estuarine and coastal waters.展开更多
Ice core provides a valuable vertical timeline of past climates and anthropogenic activities.Environmental proxies have been widely used in these studies,but there are few biological indicators available.To address th...Ice core provides a valuable vertical timeline of past climates and anthropogenic activities.Environmental proxies have been widely used in these studies,but there are few biological indicators available.To address this gap,we investigated the bacterial community from a 74 m ice core of Muztag ata glacier on the Tibetan Plateau to link biological indicators with past climate and anthropogenic activities.By analyzing the portion of the ice core with environmental proxies available(corresponding to 1907 to 1991),we observed an increase in bacterial richness throughout the ice core,which was associated with higher NH_(4)^(+),an indicator of agricultural development.The bacterial community was jointly determined by human activity,natural input,and air temperature,with a strong human influence after the 1950s.Furthermore,the relative abundance of animal gut-associated bacteria,including Aerococcaceae,Nocardiaceae,Muribaculaceae,and Lachnospiraceae,was associated with livestock number changes in the Central Asian region.Together with other bacterial lineages,they jointly explained 59.8%of the livestock number changes.This study provides quantitative evidence of the associations between bacterial indicators and past climate and human activities,highlighting the potential of using bacterial proxies for ice core studies.展开更多
The chemical oxygen demand(COD)is an essential indicator of organic pollution that represents the amount of bulk carbon in water.COD is strongly correlated with nutrient cycles and other pollutants in the environment,...The chemical oxygen demand(COD)is an essential indicator of organic pollution that represents the amount of bulk carbon in water.COD is strongly correlated with nutrient cycles and other pollutants in the environment,but it has a limited ability to quantify the amount of organic carbon(OC),of which a large proportion is made up of refractory dissolved organic carbon(RDOC)and is a potential carbon sink.Moreover,the biodegradability of OC in terms of its fate and destination should be explored,as well as how this is reflected by COD.Methods based on particle size,spectroscopy,and isotopic tracing are expected to help with deciphering the bioavailability of COD-responsive OC and explore the processes of biogeochemical cycles.As the pressure on the environment from anthropogenic inputs increases,understanding the bioavailability of OC associated with COD will help with developing more precise scientific indicators for environmental monitoring and identifying how new tools will increase knowledge of the carbon cycle.In this review,we discuss the application,scope,means,and advances of COD measurement.Based on data in the literature,we estimate the global RDOC stock and assess the impact of anthropogenic RDOC on the carbon cycle in offshore bays.This review presents new insights into the behavior of OC in aquatic environments and a potential pathway for ocean negative carbon emissions by expanding the role of RDOC as a carbon sink to offset the effect of anthropogenic carbon emissions.展开更多
Enhancing the alkalinity of the ocean is a promising approach for CO_(2)removal by promoting marine carbon sequestration.Olivine is a key candidate material for enhancing alkalinity owing to its release of silicates w...Enhancing the alkalinity of the ocean is a promising approach for CO_(2)removal by promoting marine carbon sequestration.Olivine is a key candidate material for enhancing alkalinity owing to its release of silicates when dissolved in seawater.These released compounds serve as crucial nutrients for phytoplankton such as diatoms to foster their growth,which in turn accelerates olivine dissolution and further enhances carbon sequestration.In this study,we investigated the short-term synergistic CO_(2)removal effects of an olivine-diatom coculture system.Over a 6-day incubation period,the olivine dissolution was 92%to 144%higher in the olivine-diatom groups compared with the olivine-only groups.The olivine-only groups achieved a CO_(2)removal efficiency of 5.15%to 5.49%,while the olivine-diatom groups achieved a CO_(2)removal efficiency of 8.84%to 14.44%.Adding olivine was found to increase the total alkalinity by 70 to 100μM and the diatom abundance by 26.4%to 58.4%.Diatom growth and the fixed carbon content were greatly enhanced,particularly during the later silicate-depleted stage when the Si:C ratio significantly exceeded that of groups without olivine.This mutually beneficial olivine-diatom coculture system offers a highly efficient CO_(2)removal strategy for addressing climate change.The results of this study contribute to our understanding of carbonate and biological carbon pump processes.展开更多
This paper aims to provide an overview of regional carbon fluxes and budgets in the marginal seas adjacent to China.The "China Seas" includes primarily the South China Sea, East China Sea, Yellow Sea, and th...This paper aims to provide an overview of regional carbon fluxes and budgets in the marginal seas adjacent to China.The "China Seas" includes primarily the South China Sea, East China Sea, Yellow Sea, and the Bohai Sea. Emphasis is given to CO_2 fluxes across the air-sea interface and their controls. The net flux of CO_2 degassing from the China Seas is estimated to be9.5±53 Tg C yr^(-1). The total riverine carbon flux through estuaries to the China Seas is estimated as 59.6±6.4 Tg C yr^(-1). Chinese estuaries annually emit 0.74±0.02 Tg C as CO_2 to the atmosphere. Additionally, there is a very large net carbon influx from the Western Pacific to the China Seas, amounting to ～2.5 Pg C yr^(-1). As a first-order estimate, the total export flux of particulate organic carbon from the upper ocean of the China Seas is 240±80 Tg C yr^(-1). This review also attempts to examine current knowledge gaps to promote a better understanding of the carbon cycle in this important region.展开更多
Chemical oxygen demand(COD)is widely used as an organic pollution indicator in wastewater treatment plants.Large amounts of organic matter are removed during treatment processes to meet environmental standards,and con...Chemical oxygen demand(COD)is widely used as an organic pollution indicator in wastewater treatment plants.Large amounts of organic matter are removed during treatment processes to meet environmental standards,and consequently,substantial greenhouse gases(GHGs)such as methane(CH_(4))are released.However,the COD indicator covers a great amount of refractory organic matter that is not a pollutant and could be a potential carbon sink.Here,we collected and analysed COD data from 86 worldwide municipal wastewater treatment plants(WWTPs)and applied a model published by the Intergovernmental Panel on Climate Change to estimate the emission of CH_(4) due to recalcitrant organic compound processing in China’s municipal wastewater treatment systems.Our results showed that the average contribution of refractory COD to total COD removal was55%in 86 WWTPs.The amount of CH_(4) released from the treatment of recalcitrant organic matter in 2018 could have been as high as 38.22 million tons of carbon dioxide equivalent,which amounts to the annual carbon sequestered by China’s wetlands.This suggests that the use of COD as an indicator for organic pollution is undue and needs to be revised to reduce the emission of GHG.In fact,leaving nontoxic recalcitrant organic matter in the wastewater may create a significant carbon sink and will save energy during the treatment process,aiming at carbon neutrality in the wastewater treatment industry.展开更多
Marine microbes are major drivers of marine biogeochemical cycles and play critical roles in the ecosystems. Aerobic anoxygenic phototrophic bacteria(AAPB) are an important bacterial functional group with capability o...Marine microbes are major drivers of marine biogeochemical cycles and play critical roles in the ecosystems. Aerobic anoxygenic phototrophic bacteria(AAPB) are an important bacterial functional group with capability of harvesting light energy and wide distribution, and appear to have a particular role in the ocean's carbon cycling. Yet the global pattern of AAPB distribution was controversial at the beginning of the 21 st century due to the defects of the AAPB enumeration methods. An advanced time-series observation-based infrared epifluorescence microscopy(TIREM) approach was established to amend the existing AAPB quantitative deviation and led to the accurate enumeration of AAPB in marine environments. The abundance of AAPB and AAPB% were higher in coastal and continental shelf waters than in oceanic waters, which does not support the idea that AAPB are specifically adapted to oligotrophic conditions due to photosynthesis in AAPB acting a supplement to their organic carbon respiration. Further investigation revealed that dependence of AAPB on dissolved organic carbon produced by phytoplankton(PDOC) may limit their competition and control AAPB distribution. So, the selection of carbon sources by AAPB indicated that they can effectively fractionate the carbon flow in the sea. Enlightened by these findings, the following studies on the interactions between marine microbes and DOC led to the discovery of a new mechanism of marine carbon sequestration—the Microbial Carbon Pump(MCP). The conceptual framework of MCP addresses the sources and mechanism of the vast DOC reservoir in the ocean and represents a breakthrough in the theory of ocean carbon sequestration.展开更多
基金funded by the Chinese Public Science and Technology Research Funds Projects of Ocean (No. 201305027)the National Natural Science Foundation of China (Nos. 40930847, 41376119)+1 种基金Funds of China Southern Oceano-graphic Research Center (No. 14GZP71NF35)Funds of Provincial Key Laboratory of Food Microbiology and Enzyme Engineering (No. M20140910)
文摘Coccolithophorid is unicellular marine microalgae with a global distribution in temperate and sub-temperate oceanic regions and has the ability to produce ＇the coccoliths＇. It is considered to be the second most productive calcifying organism on earth and becoming an important factor in the global carbonate cycle. Emiliania huxleyi is one of the only two bloom-forming coccolithophores and becomes a species crucial to the study of global biogeochemical cycles and climate modeling. Coccolithoviruse is a recently discovered group of viruses infecting the marine coceolithophorid E. huxleyi. They are a major cause of coceolithophore bloom termination, and DMSP concentration is increasing in the process of viral lysis. Phylogenetic evidences support that some genes are functional both in E. huxleyi and its virus （EhV）. Horizontal gene transfer （HGT） of multiple functionally coupled enzymes occurs in E. huxleyi and its DNA virus EhV has been confirmed, which contributes to the diversification and adaptation of plankton in the oceans and also critically regulates virus-host infection by allowing viruses to control host metabolic pathways for their repli- cation. Therefore, it is of particular interest to understand this host-virus interaction. On this issue, we have made a minireview of coeeolithoviruses focusing on the basic characteristics, phylogenesis, horizontal gene transfer and the interaction between the host and its viruses, as well as its important role in global biogeochemical cycling.
基金The China’s National Science Foundation grants 40331004,40706041,90711005 and 40521003
文摘A coastal upwelling event in the southern Taiwan Strait （STWS） was investigated using intensive cruise surveys （four repeated transects in a month） and satellite data in July and early August 2004. The extensive upwelling-associated surface cold water was first observed in early July （-2.0×10a km2） along the STWS coast. Then, the cold surface water reduced in size by -50% with decreased chlorophyll concentrations after 15 days, indicating the weakening of the upwelling event. At the end of July, the cold surface water disappeared. The temporal variations of the surface cold water and the 3-D hydrography around Dongshan Island are thought to be mainly attributed to the weakened upwelling-favorable southwestern wind, the asymmetric spatial structure of the wind field and the intrusion of warm water from the northern South China Sea.
基金The work was supported by Natural Science Foundation of China(Grant No. A20077023 and C40106012
文摘In this study, two common pollutants (benzo[a]pyrene and methamidophos) in marine environment were tested by comet assay for their inducement of in vivo genotoxic effect to the blood cells of black porgy ( Acanthopagrus schlegeli). The fish was exposed to 2 μg/L of benzo[a]pyrene (BaP) and methamidophos, and their mixture. The assay was performed on whole blood at 2 h, 5 h, 24 h and 96 h exposure intervals. A signifi- cant increase in DNA damage was observed in each treatment with the pollutants. Additive effect of BaP and methamidophos was also found in the experiment. However, the decrease ratios of DNA damage for 5 h and 96 h exposure interals compared with 2 h and 24 h exposure ones, respectively, were noticed. This phenomenon may be explained by the function of repairing process via enzyme cytochrome P450 in the animal. Evidence of the genotoxicity of organophosphorus pesticides (OPs) and polynuclear aromatic hydrocarbons (PAHs) on marine fish are discussed in this paper.
基金the National High-Tech Research and Development Program of China (863 Program) (No. 2002AA603013)
文摘Mud crab （Scylla serrata） is an important commercial crustacean in China. An experiment was designed to study the effect of cold stress on S. serrata. After a one-week adaptation at 28℃, the temperature is suddenly reduced to 4℃. The crabs were sampled every 2 h for 10 h and dissected immediately to measure the enzyme activity. The crabs at room temperature （28℃） were used as the control group. The activity of superoxide dismutase （SOD）, catalase （CAT） and gkttathione peroxidase （GPX）, the content of malondialdehyde （MDA） and the activity of 4 ATPases （Na^＋, K^＋-ATPase, Mg^2＋-ATPase; Ca^2＋-ATPase; Ca^2＋, Mg^2＋-ATPase） were measured biochemically. In contrast to the control group, the SOD activity increased significantly from 2 to 6 h after the cold stress, and then decreased. The CAT and GPX activities increased in 2 h, and then decreased gradually. The content of MDA increased gradually in 4 h. The activity of Na^＋, K^＋-ATPase decreased in 2 h, increased up to the top value at Hour 6, then decreased again. The activities of Mg^2＋-ATPase, Ca^2＋-ATPase and Ca^2＋, Mg^2＋-ATPase increased significantly in 6 h, insignificantly in any other hours. Under cold stress, the activity of antioxidative enzymes in S, serrata was reduced at first then stabilized, ROS-scavenging weakened, and MDA accumulated gradually in the gill after 6 h. The activity of the 4 ATPases in the crab decreased after 6 h, suggesting that the ability to regulate ion concentration has been paralyzed. Therefore, the maximum period to sustain healthy meat in the crab under cold stress is 6 hours.
基金supported by the National Natural Science Foundation of China(Grant Nos.42201147,U21A20176,42330410)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant No.2019QZKK0503)。
文摘Microorganisms play an essential role in the glacier carbon cycle;how they transform organic matter in mountain glacial cryoconite remains to be studied.Here,we applied ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS)and deep sequencing of 16S rRNA gene,to investigate the temporal microbial transformation of dissolved organic matter(DOM)of the Tibetan Plateau cryoconite.During the 60-day incubation,we found that DOM in cryoconite underwent a three-stage transformation,with decreasing bioavailability over time.The microbial community did not change much in the first week while degrading DOM molecules that were associated with higher H/C_(wa)and lower O/C_(wa).During days 15-30,DOM composition remained stable while microbial diversity increased.By day 60,the DOM was microbially converted into a higher state of recalcitrance,with higher values of aromatic index,O/C_(wa),and lower H/C_(wa),which contained molecules containing more heteroatoms.Cooperation among various microbial taxa,like Cyanobacteria,Bacteroidota,Gammaproteobacteria,Firmicutes,and Actinobacteriota,drove the DOM transformation in cryoconite.This study sheds light on the in-situ transformation of DOM composition meditated by microbial populations in cryoconite at a temporal scale,providing new insights into understanding the microbial roles in the glacier organic carbon transformation.
基金supported by the National Key Research Programs (Grant Nos. 2013CB955700 & 2016YFA0601400)the National Natural Science Foundation of China (Grant Nos. 41422603, 41676125 and 91428308)the National Programme on Global Change and Air-Sea Interaction (Grant No. GASI-0301-02-03)
文摘The oceans are the largest carbon pools on Earth, and play the role of a "buffer" in climate change. Blue carbon, the carbon(mainly organic carbon) captured by marine ecosystems, is one of the important mechanisms of marine carbon storage.Blue carbon was initially recognized only in the form of visible coastal plant carbon sequestration. In fact, microorganisms(phytoplankton, bacteria, archaea, viruses, and protozoa), which did not receive much attention in the past, account for more than 90% of the total marine biomass and are the main contributors to blue carbon. Chinese coastal seas, equivalent to 1/3 of China's total land area, have a huge carbon sink potential needing urgently research and development. In this paper, we focus on the processes and mechanisms of coastal ocean's carbon sequestration and the approaches for increasing that sequestration. We discuss the structures of coastal ecosystems, the processes of carbon cycle, and the mechanisms of carbon sequestration. Using the evolution of coastal ocean's carbon sinks in sedimentary records over geologic times, we also discuss the possible effects of natural processes and anthropogenic activities on marine carbon sinks. Finally, we discuss the prospect of using carbon sequestration engineering for increasing coastal ocean's carbon storage capacity.
基金supported by the National Key Research and Development Project of the Ministry of Science and Technology of China(Grant No.2021QZKK0102)the National Natural Science Foundation of China(Grant Nos.42222604,42188102,92251306,42141003,41861144018 and 42106040)the President’s Fund of Xiamen University(Grant Nos.20720170107 and 20720210076)。
文摘Dissolved organic matter(DOM) in the ocean is one of the largest carbon pools on Earth. Microbial metabolism is an important process that shapes the marine DOM pool. Current studies on the interactions between microorganisms and DOM focus mainly on oxic environments. Few studies have addressed the molecular characteristics of DOM in microbial-mediated transformation under anoxic/hypoxic conditions. As a result of deteriorating water quality due to eutrophication and global warming, anoxia occurs frequently in coastal waters. In this study, we performed an experiment to investigate changes in microbial community responses and the molecular characteristics of DOM in microbial-mediated transformation under hypoxic conditions. We compared microbial-mediated DOM transformation at different dissolved oxygen levels(7, 5, and 2 mg L^(-1)) and in different media(natural and artificial seawater with and without laminarin). We also investigated differences in DOM composition between groups using spectroscopic analysis and ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry. The results showed decreased microbial metabolic activity and delayed community succession at low oxygen(≤2 mg L^(-1)) in natural seawater supplemented with laminarin. The growth of strictly aerobic bacteria such as Pseudomonadaceae and Sphingomonadaceae was inhibited and the total organic carbon utilization rate was reduced by 36.9–46.7% from 4 to 32days. Moreover, tyrosine-like and tryptophan-like components were preserved, while DOM humification and modified aromaticity indices were significantly reduced under low oxygen conditions. This experiment provides justification for further study of the processes and mechanisms of improved labile DOM preservation in anoxic estuarine and coastal waters.
基金supported by the National Key Research and Development Plans(Grant No.2021YFC2300904)the National Natural Science Foundation of China(Grant Nos.U21A20176 and 42330410)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant No.2019QZKK0503)。
文摘Ice core provides a valuable vertical timeline of past climates and anthropogenic activities.Environmental proxies have been widely used in these studies,but there are few biological indicators available.To address this gap,we investigated the bacterial community from a 74 m ice core of Muztag ata glacier on the Tibetan Plateau to link biological indicators with past climate and anthropogenic activities.By analyzing the portion of the ice core with environmental proxies available(corresponding to 1907 to 1991),we observed an increase in bacterial richness throughout the ice core,which was associated with higher NH_(4)^(+),an indicator of agricultural development.The bacterial community was jointly determined by human activity,natural input,and air temperature,with a strong human influence after the 1950s.Furthermore,the relative abundance of animal gut-associated bacteria,including Aerococcaceae,Nocardiaceae,Muribaculaceae,and Lachnospiraceae,was associated with livestock number changes in the Central Asian region.Together with other bacterial lineages,they jointly explained 59.8%of the livestock number changes.This study provides quantitative evidence of the associations between bacterial indicators and past climate and human activities,highlighting the potential of using bacterial proxies for ice core studies.
基金supported by the National Natural Science Foundation of China[Project Nos.42188102,42176048,42149902 and 41930862]the Natural Science Foundation of Shandong Province[No.ZR202211220062]the Qingdao Postdoctoral Science Foundation[No.QDBSH20220201043].
文摘The chemical oxygen demand(COD)is an essential indicator of organic pollution that represents the amount of bulk carbon in water.COD is strongly correlated with nutrient cycles and other pollutants in the environment,but it has a limited ability to quantify the amount of organic carbon(OC),of which a large proportion is made up of refractory dissolved organic carbon(RDOC)and is a potential carbon sink.Moreover,the biodegradability of OC in terms of its fate and destination should be explored,as well as how this is reflected by COD.Methods based on particle size,spectroscopy,and isotopic tracing are expected to help with deciphering the bioavailability of COD-responsive OC and explore the processes of biogeochemical cycles.As the pressure on the environment from anthropogenic inputs increases,understanding the bioavailability of OC associated with COD will help with developing more precise scientific indicators for environmental monitoring and identifying how new tools will increase knowledge of the carbon cycle.In this review,we discuss the application,scope,means,and advances of COD measurement.Based on data in the literature,we estimate the global RDOC stock and assess the impact of anthropogenic RDOC on the carbon cycle in offshore bays.This review presents new insights into the behavior of OC in aquatic environments and a potential pathway for ocean negative carbon emissions by expanding the role of RDOC as a carbon sink to offset the effect of anthropogenic carbon emissions.
基金supported by the National Natural Science Foundation of China(42188102,42222604,and 92351303)the Joint Funds of the National Natural Science Foun-dation of China(U1906216)+3 种基金the Chinese Academy of Sciences(project XK2022DXA001)the Marine Economic Develop-ment Program of Fujian Province(grant no.FJHJF-L-2022-11)the Fundamental Research Funds for the Central Universities(20720190095)funds from the Third Institute of Oceano-graphy,Ministry of Natural Resources(grant EPR2022001).
文摘Enhancing the alkalinity of the ocean is a promising approach for CO_(2)removal by promoting marine carbon sequestration.Olivine is a key candidate material for enhancing alkalinity owing to its release of silicates when dissolved in seawater.These released compounds serve as crucial nutrients for phytoplankton such as diatoms to foster their growth,which in turn accelerates olivine dissolution and further enhances carbon sequestration.In this study,we investigated the short-term synergistic CO_(2)removal effects of an olivine-diatom coculture system.Over a 6-day incubation period,the olivine dissolution was 92%to 144%higher in the olivine-diatom groups compared with the olivine-only groups.The olivine-only groups achieved a CO_(2)removal efficiency of 5.15%to 5.49%,while the olivine-diatom groups achieved a CO_(2)removal efficiency of 8.84%to 14.44%.Adding olivine was found to increase the total alkalinity by 70 to 100μM and the diatom abundance by 26.4%to 58.4%.Diatom growth and the fixed carbon content were greatly enhanced,particularly during the later silicate-depleted stage when the Si:C ratio significantly exceeded that of groups without olivine.This mutually beneficial olivine-diatom coculture system offers a highly efficient CO_(2)removal strategy for addressing climate change.The results of this study contribute to our understanding of carbonate and biological carbon pump processes.
基金supported by the National Natural Science Foundation of China (Grant Nos.91328202 & 91428308)the Major Scientific Research Program of the Ministry of Science and Technology (Grant No. 2015CB954001)+1 种基金the Marine Public Welfare Project of the State Oceanic Administration (Grant No. 201505003-3)the Global Change Program (Grant No. GASI-0301-02-02)
文摘This paper aims to provide an overview of regional carbon fluxes and budgets in the marginal seas adjacent to China.The "China Seas" includes primarily the South China Sea, East China Sea, Yellow Sea, and the Bohai Sea. Emphasis is given to CO_2 fluxes across the air-sea interface and their controls. The net flux of CO_2 degassing from the China Seas is estimated to be9.5±53 Tg C yr^(-1). The total riverine carbon flux through estuaries to the China Seas is estimated as 59.6±6.4 Tg C yr^(-1). Chinese estuaries annually emit 0.74±0.02 Tg C as CO_2 to the atmosphere. Additionally, there is a very large net carbon influx from the Western Pacific to the China Seas, amounting to ～2.5 Pg C yr^(-1). As a first-order estimate, the total export flux of particulate organic carbon from the upper ocean of the China Seas is 240±80 Tg C yr^(-1). This review also attempts to examine current knowledge gaps to promote a better understanding of the carbon cycle in this important region.
基金supported by the National Basic Science Center of National Natural Science Foundation of China,National Key R&D Program(Grant No.2016YFA0601400)the National Natural Science Foundation of China(Grant Nos.91751207 and 41861144018)。
文摘Chemical oxygen demand(COD)is widely used as an organic pollution indicator in wastewater treatment plants.Large amounts of organic matter are removed during treatment processes to meet environmental standards,and consequently,substantial greenhouse gases(GHGs)such as methane(CH_(4))are released.However,the COD indicator covers a great amount of refractory organic matter that is not a pollutant and could be a potential carbon sink.Here,we collected and analysed COD data from 86 worldwide municipal wastewater treatment plants(WWTPs)and applied a model published by the Intergovernmental Panel on Climate Change to estimate the emission of CH_(4) due to recalcitrant organic compound processing in China’s municipal wastewater treatment systems.Our results showed that the average contribution of refractory COD to total COD removal was55%in 86 WWTPs.The amount of CH_(4) released from the treatment of recalcitrant organic matter in 2018 could have been as high as 38.22 million tons of carbon dioxide equivalent,which amounts to the annual carbon sequestered by China’s wetlands.This suggests that the use of COD as an indicator for organic pollution is undue and needs to be revised to reduce the emission of GHG.In fact,leaving nontoxic recalcitrant organic matter in the wastewater may create a significant carbon sink and will save energy during the treatment process,aiming at carbon neutrality in the wastewater treatment industry.
基金Ministry of Science and Technology of the People’s Republic of China Project (Grant No. 2011IM010700)the National Natural Science Foundation of China (Grant Nos. 91428308, 41422603 and 41176095)the State Oceanic Administration of China Project (Grant No. GASI-03-01-02-03)
文摘Marine microbes are major drivers of marine biogeochemical cycles and play critical roles in the ecosystems. Aerobic anoxygenic phototrophic bacteria(AAPB) are an important bacterial functional group with capability of harvesting light energy and wide distribution, and appear to have a particular role in the ocean's carbon cycling. Yet the global pattern of AAPB distribution was controversial at the beginning of the 21 st century due to the defects of the AAPB enumeration methods. An advanced time-series observation-based infrared epifluorescence microscopy(TIREM) approach was established to amend the existing AAPB quantitative deviation and led to the accurate enumeration of AAPB in marine environments. The abundance of AAPB and AAPB% were higher in coastal and continental shelf waters than in oceanic waters, which does not support the idea that AAPB are specifically adapted to oligotrophic conditions due to photosynthesis in AAPB acting a supplement to their organic carbon respiration. Further investigation revealed that dependence of AAPB on dissolved organic carbon produced by phytoplankton(PDOC) may limit their competition and control AAPB distribution. So, the selection of carbon sources by AAPB indicated that they can effectively fractionate the carbon flow in the sea. Enlightened by these findings, the following studies on the interactions between marine microbes and DOC led to the discovery of a new mechanism of marine carbon sequestration—the Microbial Carbon Pump(MCP). The conceptual framework of MCP addresses the sources and mechanism of the vast DOC reservoir in the ocean and represents a breakthrough in the theory of ocean carbon sequestration.
