The Changjiang River in China was dammed in 2003. The possible changes in matters fluxes from the river downstream after the completion of Three Gorges Dam and their potential impacts on the ecosystem of the East Chin...The Changjiang River in China was dammed in 2003. The possible changes in matters fluxes from the river downstream after the completion of Three Gorges Dam and their potential impacts on the ecosystem of the East China Sea are discussed . The estuarine and coastal waters in the East China Sea were heavily fertilized by the inflow of nutrient-rich freshwater from the Changjiang River, which has led to severe eutrophication and frequent harmful algal blooms ,thus worsening the ecosystem health in this area. Analy- sis showed that the nutrient loadings are very likely to be reduced in the lower Changjiang River due to the construction of Three Gorges Dam. Especially for the total phosphorus, the discharges to the East China Sea will be reduced by one-third, which would relieve the severe eutrophication in this area. However, the expected decrease in the riverine silicate discharge would lead the ratio of silicon to nitrogen to be much less than 1 in the estuarine and coastal waters and thus may cause an elevation of flagellate growth. The changes in the annual water discharges and their seasonal distributions below the dam will be minor. Reduction of suspended particulate matter loading, due to the sedimentation behind the dam, will reduce the nutrient loadings of the particulate form especially for phosphorus, and decrease the turbidity of estuarine and coastal waters. On the other hand, this may enhance the erosion of the delta and the coasts as well as modifythe benthic ecosystem.展开更多
Sediment-water fluxes of N and P species in the Bohai Sea were investigated in Septem-ber-October 1998 and April-May 1999. The benthic fluxes of nutrient species were determined by incubating sediment core samples wit...Sediment-water fluxes of N and P species in the Bohai Sea were investigated in Septem-ber-October 1998 and April-May 1999. The benthic fluxes of nutrient species were determined by incubating sediment core samples with bottom seawater bubbled with air or nitrogen. -2NO,+4NH, dissolved organic nitrogen (DON) and phosphorus (DOP), total dissolved nitrogen (TDN) and phosphorus (TDP), and -34PO showed a net exchange flux from seawater to sediment, while -3NO, dissolved inorganic nitrogen (DIN) and -23SiO were released from sediment to seawater in the Bohai Sea. Sediment-water nutrient exchange increases DIN and reduces the phosphorus load in the Bohai Sea. The release of silicate from sediment to overlying seawater reduces potential silicate limitation of primary production resulted from decrease of riverine discharge. The exchange flux of nutrients showed no obvious seasonal variation. The present study showed that the concentrations and composition of nutrients in the water column were affected by suspended sediment, and that not all the exchangeable phosphate in sediment could be released via sediment resuspension.展开更多
A total of 67 samples from the upper and lower sediment traps in the central South China Sea were analyzed, which were collected during 1993 ~ 1996. It is indicated that the distribution of stable isotope values, surf...A total of 67 samples from the upper and lower sediment traps in the central South China Sea were analyzed, which were collected during 1993 ~ 1996. It is indicated that the distribution of stable isotope values, surface primary productivity, fluxes of total particulate matter, carbonate, biogenic opal, organic carbon, planktonic foraminiferal species and their total amount exhibit obviously seasonal and annual fluctuations. High values of the fluxes occurred in the prevailing periods of the northeastern and southwestern monsoons, and the low values occurred during the periods between the two monsoons. The fluxes of some planktonic foraminiferal species （ Globigerinoides sacculifer , G. ruber , Globigerinita glutinata, Neogloboquadrina dutertrei ） and their percentages also exhibit two prominent peaks during the prevailing periods of the northeastern and southwestern monsoons respectively, while those of Globigerina bulloides, Globorotalia menardii and Pulleniatina obliquiloculata only exhibit one peak in the prevailing periods of the northeastern monsoon. In addition, fluxes and percentages of Globigerinoides sacculifer and Globorotalia menardii as well as the fluxes of carbonate and total amount of planktonic foraminifera decrease gradually from 1993 to 1996, and those of Globigerina bulloides, Globigerinita glutinata and biogenic opal increase gradually from 1993 to 1996. The fluxes of carbonate and organic carbon in the upper trap are higher than those in the lower one. The study indicates that the seasonal and annual variations of the sediment fluxes and planktonic foraminiferal species are mainly controlled by the changes of surface primary productivity and hydrological conditions related to the East Asian monsoon. The lower carbonate and organic carbon fluxes in the lower trap are related to the dissolution.展开更多
In recent decades,endocrine-disrupting chemicals(EDCs)have emerged as a prominent focus on environmental science and policy.Notably,extensive use of in vitro bioassays founded on ligand-receptor binding has facilitate...In recent decades,endocrine-disrupting chemicals(EDCs)have emerged as a prominent focus on environmental science and policy.Notably,extensive use of in vitro bioassays founded on ligand-receptor binding has facilitated the identification of a substantial number of potential EDCs,particularly agonists/antagonists of nuclear receptors such as estrogen receptors and thyroid hormone receptors[1].These datasets have significantly augmented the discovery of potential EDCs.However,when subjecting these compounds to in vivo exposures,spanning from teleost fish to rodents and humans,observations frequently deviated from in vitro anticipation[2,3].This discrepancy and the apparent lack of prognostic value are shared with the difficulties of in vitro-in vivo extrapolations in classical toxicological endpoints.While the utility of in vitro identification is without doubt,its potential EDCs require in vivo confirmation.The resulting complexity in EDCs outcomes,nevertheless,has not yet received adequate attention and thorough interpretation.展开更多
Dongsha Island and the adjacent sea area locate at the northern continental margin of the South China Sea (SCS), and is connected to the east by the Manila Trench. Analyses of seismic stratigraphy and gravity, magneti...Dongsha Island and the adjacent sea area locate at the northern continental margin of the South China Sea (SCS), and is connected to the east by the Manila Trench. Analyses of seismic stratigraphy and gravity, magnetic and drilling wells data led to the discovery of three post fault sequences (V, VI, VII). Extensive tectonic uplift, magma activity and erosion occurred in Dongsha Island and the adjacent area, where most of the faults in the northeastern SCS were still active during Pliocene and Quaternary. Two groups of faults trending NEE and NW were developed during Late Cenozoic. We conclude that three important tectonic movements, especially Dongsha movement (4.4-5.2 Ma) and Liuhua movement (1.4-1.89 Ma), controlled the structural framework in the Dongsha rise; whose deformation in the east is stronger than that in the west and whose stress field variation suggests that the tectonic uplift in the study area contributed to magmato tectonic events correlated to the main collision phases between the East China and Taiwan 5-3 and 3-0 Ma ago.展开更多
A zero dimensional box model (PNCMjzb) with six state variables (ammonium, nitrate, dissolved organic nitrogen, phytoplankton, zooplankton and detritus) was developed to study nitrogen cycling in the Jiaozhou Bay pela...A zero dimensional box model (PNCMjzb) with six state variables (ammonium, nitrate, dissolved organic nitrogen, phytoplankton, zooplankton and detritus) was developed to study nitrogen cycling in the Jiaozhou Bay pelagic ecosystem. The dominant processes within these compartments are considered with nitrogen as flow currency. Phytoplankton and zooplankton are treated as separate state variables, assuming that the species composition was dominated by two or three species the dynamic constants of which are similar and that they represent the entire plankton community. The microbial loop has not been integrated explicitly in the model. The turnover of bacteria is included implicitly in processes such as detritus decomposition, DON remineralization, pelagic nitrification and denitrification. The model is driven by two forcing variables, viz. water temperature and light intensity. Historical data from the1980s and 1990s were compiled and used for model calibration. In this paper (part I), the consideration of every main compartment in the model is interpreted in detail. And the applied equations and parameters are presented. The main results from the simulations together with discussion about phytoplankton dynamics and primary production in Jiaozhou Bay are presented in the next paper (part II).展开更多
Tie-series sediment trap materials at different water depths and surface sediments in northern and central South China Sea (SCS) were analyzed for organic carbon, amino acids, amino sugars and carbohydrates. Results s...Tie-series sediment trap materials at different water depths and surface sediments in northern and central South China Sea (SCS) were analyzed for organic carbon, amino acids, amino sugars and carbohydrates. Results show that particulate organic carbon (POC) is mainly derived from marine plankton, only 1.4%–1.6% of primary production sinks into deep SCS water column and less than 0.22 % of primary production ultimately reaches the sediments. The ranineralization and dissolution of organic matter as well as the compositional alterations of organic matter mixtures may mainly take place in the upper few hundred meters of water column, deep carbonate (opal) lysocline zones, and interface layers between sediments and water column, rather than in mid-waters. The organic geochemical parameters such as (T aa +T sug )OC%, AA/AS, Gluam/Galam, Arom. AA/non-prot. AA, ASP/b-ALA, Glu/g-ABA decrease from living marine plankton (or planktonic shells), to settling particulate matter and to sediments suggesting that they appear to be gad early degraded indicators of organic matter.展开更多
The mobility,bioavailability,and environmental fate of heavy metals in soil are controlled by their adsorption onto soil minerals and solid organic matter.The adsorption is strongly affected by the presence of various...The mobility,bioavailability,and environmental fate of heavy metals in soil are controlled by their adsorption onto soil minerals and solid organic matter.The adsorption is strongly affected by the presence of various low-molecular-weight organic acids.In this study,effect of hydroxamate siderophore desferrioxamine B (DFOB) on cadmium (Cd) and zinc (Zn) adsorption onto two micaceous clay minerals,muscovite and phlogopite,was evaluated in batch experiments.Results showed that the presence of DFOB diminished the adsorption of Cd and Zn onto both minerals,particularly under neutral to alkaline pH conditions.For instance,at pH 8.2,the presence of DFOB caused a decrease in the adsorption of Zn onto phlogopite by nearly 50%.The equilibrium adsorption of Cd and Zn was satisfactorily described using Freundlich isotherm.The adsorption isotherms showed that the affinity of Cd and Zn onto the minerals decreased in the presence of DFOB.For example,at pH 8.0,the presence of siderophore caused a decrease in the Freundlich adsorption isotherm coefficient KF for Zn adsorption onto muscovite and phlogopite from 4.60 to 0.07 L g^-1 and from 3.56 to 0.36 L g^-1,respectively.These findings confirm the potential influence of siderophore on the fate of Cd and Zn in arid soils containing substantial contributions of micaceous silicate minerals.展开更多
The lockdown of large parts of Chinese economy beginning in late January 2020 lead to significant regional changes of aerosol loads, which suggests a reduction of backscatter and consequently a regional warming in the...The lockdown of large parts of Chinese economy beginning in late January 2020 lead to significant regional changes of aerosol loads, which suggests a reduction of backscatter and consequently a regional warming in the following months. Using local data and a numerical experiment with a limited area model, we have examined how strong this response may have been. The observed (local and reanalysis) observations point to a warming of less than 1.0 K, the simulations to a warming of the order of 0.5 K. These numbers are uncertain, because of large-scale natural variability and an ad-hoc choice of aerosol optical depth anomaly in the simulation. Thus, the result was, in short, that there was actually a weak warming of a few tenth of degrees, while noteworthy changes in circulation or in precipitation were not detected. More specifically, we found that at selected central China stations temperatures were found to be higher than in previous two years. This warming goes with a marked diurnal signal, with a maximum warming in the early afternoon (06 UTC), weakest at night (18 UTC). This may be related to a general warming of large swaths of Asia (including Siberia, which is not related to local aerosol forcing). Indeed, also the stations outside the immediate strong lockdown region are showing warming, albeit a weaker one. Thus, the difference 2020 minus 2019/2018 may overestimate the effect. The ad-hoc series of numerical experiments indicates that the simulated changes are robust and suffer little from internal dynamical variability. In particular, the overall reduction of the aerosol optical depth does not lead to phases of larger intermittent divergence among the model simulations, irrespective of the aerosol load. Instead, the simulations with reduced anthropogenic aerosol load show more a mere locally increased temperature. This may indicate that the aerosol effect is mostly thermodynamic in all local air columns in the region.展开更多
基金The National Key Basic Research Program of Ministry of Science and Technology of China under contract No.2001CB4097the Foundation of Key Laboratory of Marine Ecosystem and Biogeochemistry of State Oceanic Administration of China under contract No.LMEB200603.
文摘The Changjiang River in China was dammed in 2003. The possible changes in matters fluxes from the river downstream after the completion of Three Gorges Dam and their potential impacts on the ecosystem of the East China Sea are discussed . The estuarine and coastal waters in the East China Sea were heavily fertilized by the inflow of nutrient-rich freshwater from the Changjiang River, which has led to severe eutrophication and frequent harmful algal blooms ,thus worsening the ecosystem health in this area. Analy- sis showed that the nutrient loadings are very likely to be reduced in the lower Changjiang River due to the construction of Three Gorges Dam. Especially for the total phosphorus, the discharges to the East China Sea will be reduced by one-third, which would relieve the severe eutrophication in this area. However, the expected decrease in the riverine silicate discharge would lead the ratio of silicon to nitrogen to be much less than 1 in the estuarine and coastal waters and thus may cause an elevation of flagellate growth. The changes in the annual water discharges and their seasonal distributions below the dam will be minor. Reduction of suspended particulate matter loading, due to the sedimentation behind the dam, will reduce the nutrient loadings of the particulate form especially for phosphorus, and decrease the turbidity of estuarine and coastal waters. On the other hand, this may enhance the erosion of the delta and the coasts as well as modifythe benthic ecosystem.
基金This study was funded by NSFC (Nos. 40036010 and 40206017) and the Special Funds from National Key Basic Research Program of P. R. China (No. 2001CB409703).
文摘Sediment-water fluxes of N and P species in the Bohai Sea were investigated in Septem-ber-October 1998 and April-May 1999. The benthic fluxes of nutrient species were determined by incubating sediment core samples with bottom seawater bubbled with air or nitrogen. -2NO,+4NH, dissolved organic nitrogen (DON) and phosphorus (DOP), total dissolved nitrogen (TDN) and phosphorus (TDP), and -34PO showed a net exchange flux from seawater to sediment, while -3NO, dissolved inorganic nitrogen (DIN) and -23SiO were released from sediment to seawater in the Bohai Sea. Sediment-water nutrient exchange increases DIN and reduces the phosphorus load in the Bohai Sea. The release of silicate from sediment to overlying seawater reduces potential silicate limitation of primary production resulted from decrease of riverine discharge. The exchange flux of nutrients showed no obvious seasonal variation. The present study showed that the concentrations and composition of nutrients in the water column were affected by suspended sediment, and that not all the exchangeable phosphate in sediment could be released via sediment resuspension.
文摘A total of 67 samples from the upper and lower sediment traps in the central South China Sea were analyzed, which were collected during 1993 ~ 1996. It is indicated that the distribution of stable isotope values, surface primary productivity, fluxes of total particulate matter, carbonate, biogenic opal, organic carbon, planktonic foraminiferal species and their total amount exhibit obviously seasonal and annual fluctuations. High values of the fluxes occurred in the prevailing periods of the northeastern and southwestern monsoons, and the low values occurred during the periods between the two monsoons. The fluxes of some planktonic foraminiferal species （ Globigerinoides sacculifer , G. ruber , Globigerinita glutinata, Neogloboquadrina dutertrei ） and their percentages also exhibit two prominent peaks during the prevailing periods of the northeastern and southwestern monsoons respectively, while those of Globigerina bulloides, Globorotalia menardii and Pulleniatina obliquiloculata only exhibit one peak in the prevailing periods of the northeastern monsoon. In addition, fluxes and percentages of Globigerinoides sacculifer and Globorotalia menardii as well as the fluxes of carbonate and total amount of planktonic foraminifera decrease gradually from 1993 to 1996, and those of Globigerina bulloides, Globigerinita glutinata and biogenic opal increase gradually from 1993 to 1996. The fluxes of carbonate and organic carbon in the upper trap are higher than those in the lower one. The study indicates that the seasonal and annual variations of the sediment fluxes and planktonic foraminiferal species are mainly controlled by the changes of surface primary productivity and hydrological conditions related to the East Asian monsoon. The lower carbonate and organic carbon fluxes in the lower trap are related to the dissolution.
基金supported by the National Natural Science Foundation of China(22122605)the National Key Research and Development Program of China(2022YFC3902100).
文摘In recent decades,endocrine-disrupting chemicals(EDCs)have emerged as a prominent focus on environmental science and policy.Notably,extensive use of in vitro bioassays founded on ligand-receptor binding has facilitated the identification of a substantial number of potential EDCs,particularly agonists/antagonists of nuclear receptors such as estrogen receptors and thyroid hormone receptors[1].These datasets have significantly augmented the discovery of potential EDCs.However,when subjecting these compounds to in vivo exposures,spanning from teleost fish to rodents and humans,observations frequently deviated from in vitro anticipation[2,3].This discrepancy and the apparent lack of prognostic value are shared with the difficulties of in vitro-in vivo extrapolations in classical toxicological endpoints.While the utility of in vitro identification is without doubt,its potential EDCs require in vivo confirmation.The resulting complexity in EDCs outcomes,nevertheless,has not yet received adequate attention and thorough interpretation.
文摘Dongsha Island and the adjacent sea area locate at the northern continental margin of the South China Sea (SCS), and is connected to the east by the Manila Trench. Analyses of seismic stratigraphy and gravity, magnetic and drilling wells data led to the discovery of three post fault sequences (V, VI, VII). Extensive tectonic uplift, magma activity and erosion occurred in Dongsha Island and the adjacent area, where most of the faults in the northeastern SCS were still active during Pliocene and Quaternary. Two groups of faults trending NEE and NW were developed during Late Cenozoic. We conclude that three important tectonic movements, especially Dongsha movement (4.4-5.2 Ma) and Liuhua movement (1.4-1.89 Ma), controlled the structural framework in the Dongsha rise; whose deformation in the east is stronger than that in the west and whose stress field variation suggests that the tectonic uplift in the study area contributed to magmato tectonic events correlated to the main collision phases between the East China and Taiwan 5-3 and 3-0 Ma ago.
基金Thisworkwasundertheframeworkoftheco operativeprojectbetweentheOceanUniversityofChinaandUniversityofHam burg (UJEK No.0 3F0 1 89B)
文摘A zero dimensional box model (PNCMjzb) with six state variables (ammonium, nitrate, dissolved organic nitrogen, phytoplankton, zooplankton and detritus) was developed to study nitrogen cycling in the Jiaozhou Bay pelagic ecosystem. The dominant processes within these compartments are considered with nitrogen as flow currency. Phytoplankton and zooplankton are treated as separate state variables, assuming that the species composition was dominated by two or three species the dynamic constants of which are similar and that they represent the entire plankton community. The microbial loop has not been integrated explicitly in the model. The turnover of bacteria is included implicitly in processes such as detritus decomposition, DON remineralization, pelagic nitrification and denitrification. The model is driven by two forcing variables, viz. water temperature and light intensity. Historical data from the1980s and 1990s were compiled and used for model calibration. In this paper (part I), the consideration of every main compartment in the model is interpreted in detail. And the applied equations and parameters are presented. The main results from the simulations together with discussion about phytoplankton dynamics and primary production in Jiaozhou Bay are presented in the next paper (part II).
基金Project supported by the National Natural Science Foundation of China (Grant No. 49776297)Cruises financially supported by State Oceanic Administration and German Federal Ministry of Research and Technology
文摘Tie-series sediment trap materials at different water depths and surface sediments in northern and central South China Sea (SCS) were analyzed for organic carbon, amino acids, amino sugars and carbohydrates. Results show that particulate organic carbon (POC) is mainly derived from marine plankton, only 1.4%–1.6% of primary production sinks into deep SCS water column and less than 0.22 % of primary production ultimately reaches the sediments. The ranineralization and dissolution of organic matter as well as the compositional alterations of organic matter mixtures may mainly take place in the upper few hundred meters of water column, deep carbonate (opal) lysocline zones, and interface layers between sediments and water column, rather than in mid-waters. The organic geochemical parameters such as (T aa +T sug )OC%, AA/AS, Gluam/Galam, Arom. AA/non-prot. AA, ASP/b-ALA, Glu/g-ABA decrease from living marine plankton (or planktonic shells), to settling particulate matter and to sediments suggesting that they appear to be gad early degraded indicators of organic matter.
基金the Vali-e-Asr University of Rafsanjan, Iran, for ?nancial support (No. 436753)
文摘The mobility,bioavailability,and environmental fate of heavy metals in soil are controlled by their adsorption onto soil minerals and solid organic matter.The adsorption is strongly affected by the presence of various low-molecular-weight organic acids.In this study,effect of hydroxamate siderophore desferrioxamine B (DFOB) on cadmium (Cd) and zinc (Zn) adsorption onto two micaceous clay minerals,muscovite and phlogopite,was evaluated in batch experiments.Results showed that the presence of DFOB diminished the adsorption of Cd and Zn onto both minerals,particularly under neutral to alkaline pH conditions.For instance,at pH 8.2,the presence of DFOB caused a decrease in the adsorption of Zn onto phlogopite by nearly 50%.The equilibrium adsorption of Cd and Zn was satisfactorily described using Freundlich isotherm.The adsorption isotherms showed that the affinity of Cd and Zn onto the minerals decreased in the presence of DFOB.For example,at pH 8.0,the presence of siderophore caused a decrease in the Freundlich adsorption isotherm coefficient KF for Zn adsorption onto muscovite and phlogopite from 4.60 to 0.07 L g^-1 and from 3.56 to 0.36 L g^-1,respectively.These findings confirm the potential influence of siderophore on the fate of Cd and Zn in arid soils containing substantial contributions of micaceous silicate minerals.
文摘The lockdown of large parts of Chinese economy beginning in late January 2020 lead to significant regional changes of aerosol loads, which suggests a reduction of backscatter and consequently a regional warming in the following months. Using local data and a numerical experiment with a limited area model, we have examined how strong this response may have been. The observed (local and reanalysis) observations point to a warming of less than 1.0 K, the simulations to a warming of the order of 0.5 K. These numbers are uncertain, because of large-scale natural variability and an ad-hoc choice of aerosol optical depth anomaly in the simulation. Thus, the result was, in short, that there was actually a weak warming of a few tenth of degrees, while noteworthy changes in circulation or in precipitation were not detected. More specifically, we found that at selected central China stations temperatures were found to be higher than in previous two years. This warming goes with a marked diurnal signal, with a maximum warming in the early afternoon (06 UTC), weakest at night (18 UTC). This may be related to a general warming of large swaths of Asia (including Siberia, which is not related to local aerosol forcing). Indeed, also the stations outside the immediate strong lockdown region are showing warming, albeit a weaker one. Thus, the difference 2020 minus 2019/2018 may overestimate the effect. The ad-hoc series of numerical experiments indicates that the simulated changes are robust and suffer little from internal dynamical variability. In particular, the overall reduction of the aerosol optical depth does not lead to phases of larger intermittent divergence among the model simulations, irrespective of the aerosol load. Instead, the simulations with reduced anthropogenic aerosol load show more a mere locally increased temperature. This may indicate that the aerosol effect is mostly thermodynamic in all local air columns in the region.
