Phosphorus is a key element and plays an important role in global biogeochemical cycles. The evolution of sedimentary environment is also influenced by phosphorus concentrations and fractions as well as phosphate sorp...Phosphorus is a key element and plays an important role in global biogeochemical cycles. The evolution of sedimentary environment is also influenced by phosphorus concentrations and fractions as well as phosphate sorption characteristics of the marine sediments. The geochemical characteristics of phosphorus and their environmental records were presented in Jiaozhou Bay sediments. Profiles of different forms of phosphorus were measured as well as the roles and vertical distributions of phosphorus forms in response to sedimentary environment changes were investigated. The results showed that inorganic phosphorus （IP） was the major fraction of total phosphorus （TP）; phosphorus which is bound to calcium, iron and occluded phosphorus, as well as the exchangeable phosphorus were the main forms of IP, especially calcium - phosphorus, including detrital carbonate-bound phosphorus （Det- P） and authigenic apatite-bound phosphorus （ACa- P）, are the uppermost constituent of IP in Jiaozhou Bay sediments. Moreover, the lead-210 chronology technology was employed to estimate how much phosphorus was buried ultimately in sediments. And the research showed that the impacts of human activities have increased remarkably in recent years especially between the 1980s and 2000. According to research, the development of Jiaozhou Bay environment in the past hundred years can be divided into three stages ： （ 1 ） before the 1980s characterized by the relatively low sedimentation rate, weak land-derived phosphorus inputs and low anthropogenic impacts; （2） from the 1980s to around 2000, accelerating in the 1990s, during which high sedimentation rates, high phosphorus abundance and burial fluxes due to the severe human activities impacted on the whole environmental system ; （ 3 ） after 2000, the period of the improvement of environment, the whole system has been improved including the decreasing sedimentation rates, concentration and the burial fluxes of phosphorus.展开更多
Sixteen polycyclic aromatic hydrocarbons （PAHs） and 28 polychlorinated biphenyls （PCBs） were measured at a 2-cm interval in a core sample from the middle of the southern Yellow Sea for elucidating their historical...Sixteen polycyclic aromatic hydrocarbons （PAHs） and 28 polychlorinated biphenyls （PCBs） were measured at a 2-cm interval in a core sample from the middle of the southern Yellow Sea for elucidating their historical variations in inflow and sources. The chronology was obtained using the ^210Pb method. PAHs concentrations decreased generally with depth and two climax values occurred in 14-16 cm and 20-22 cm layers, demonstrating that the production and usage of PAHs might reach peaks in the periods of 1956-1962 and 1938-1944. The booming economy and the navy battles of the Second World War might explain why the higher levels were detected in the two layers. The result of principal component analysis （PCA） revealed that PAHs were primarily owing to the combustion product. Down-cored variation of PCB concentrations was complex. Higher concentrations besides the two peaks being the same as PAHs were detected from 4 to 8 cm, depositing from 1980 to 1992, which probably resulted from the disposal of the out-dated PCB-containing equipment. The average Cl percentage of PCBs detected was similar to that of the mixture of Aroclor 1254 and 1242, suggesting they might origin from the dielectrical and heat-transfer fluid. The total organic carbon （TOC） content played a prevalent role in the adsorption of high molecular weight PAHs （≥ring）, while no obvious relationship among total PCBs, the concentration of congeners, and TOC was found.展开更多
The Jiaozhou Bay is characterized by heavy eutrophication that is associated with intensive anthropogenic activities. Four core sediments from the Jiaozhou Bay are analyzed using bulk technologies, including sedimenta...The Jiaozhou Bay is characterized by heavy eutrophication that is associated with intensive anthropogenic activities. Four core sediments from the Jiaozhou Bay are analyzed using bulk technologies, including sedimentary total organic carbon（TOC）, total nitrogen（TN）, the stable carbon（δ13C） and nitrogen（δ15 N） isotopic composition to obtain the comprehensive understanding of the source and composition of sedimentary organic matter and further shed light on the environmental changes of the Jiaozhou Bay on a centennial time scale.Results suggest that the TOC and TN concentrations increase in the upper core, having indicated a probable eutrophication process since the 1920 s in the inner bay and the 2000 s in the bay mouth. The TOC and TN concentrations outside the bay have also changed since 1916 owing to the variation of terrigenous input.Considering TOC/TN ratio, δ13 C and δ15 N, it can be concluded there is a mixture of terrigenous and marine organic matter sources in the study area. A simple two end-member（terrigenous and marine） mixing model usingδ13 C indicats that 45%–79% of TOC in the Jiaozhou Bay is from the marine source. The environmental changes of the Jiaozhou Bay are recorded by geochemical proxies, which are influenced by the intensive anthropogenic activities（e.g., extensive use of fertilizers, and discharge of sewage） and climate changes（e.g., rainfall）.展开更多
The results of field observation carried out in May 2003 were used to examine pH and total alkalinity behaviors in the Changjiang Estuary. It was showed that pH and total alkalinity took on clear spatial variations in...The results of field observation carried out in May 2003 were used to examine pH and total alkalinity behaviors in the Changjiang Estuary. It was showed that pH and total alkalinity took on clear spatial variations in values with the minima in the low salinity region. Like salinity, transect distributions of pH and total alkalinity （TA） in a downriver direction had a sharp gradient each. These gradients appeared in such a sequence that the TA gradient was earlier than salinity and pH gradients, and the salinity gradient was earlier than the pH gradient. These distribution characteristics seemed to be strongly influenced by the mixing process of freshwater and seawater, for both pH and total alkalinity had significant linear relationships with salinity and temperature. For pH, phytoplankton activities also had a significant impact upon its spatial distribution. During a period of 48 h, pH and total alkalinity changed within wide ranges for every layer of the two anchor stations, namely, Stas 13 and 20, which were located at the mixed water mass and seawater mass, respectively. For both Stas 13 and 20, pH and TA fluctuation of every layer could be very wide during a 4 h period. As a whole, the data of the two anchor stations showed that neither variations in salinity and temperature nor phytoplankton activities were the main factors strongly influencing the total alkalinity temporal variability on a small time scale. The data of Sta. 20 implied that both salinity variation and phytoplankton activities had a significant influence on pH temporal variability, but the same conclusion could not be drawn from the data of Sta. 13.展开更多
Dissolved selenium in the Changjiang（Yangtze） Estuary and its adjacent waters was determined by hydride generation atomic fluorescence spectrometry to elucidate the source, behavior in estuary, adsorption-desorption...Dissolved selenium in the Changjiang（Yangtze） Estuary and its adjacent waters was determined by hydride generation atomic fluorescence spectrometry to elucidate the source, behavior in estuary, adsorption-desorption process and biological role. In surface water, Se（IV） concentration ranged 0.05–1.14 nmol/L and Se（VI） concentration varied 0.01–1.20 nmol/L, with the means of 0.76 and 0.49 nmol/L, respectively. In bottom water, Se（IV） content varied 0.03–0.27 nmol/L and Se（VI） content ranged 0.04–0.85 nmol/L, with the averages of 0.10 and 0.40 nmol/L, respectively. High level of Se（IV） was observed near the shore with a significant decrease towards the open sea, suggesting the continental input from the adjacent rivers. Large value of Se（VI） was found in bottom water, reflecting the release from suspended sediment. Besides, high value appeared in the same latitude of the Changjiang Estuary and Hangzhou Bay illustrated the effect of lateral mixing and the long-distance transport of selenium. Se（VI）, more soluble, occupied higher percentage in aqueous environment. The presence of Se（IV） resulted from the degradation of residue and the reduction of Se（VI） under anaerobic condition. The positive relationship to suspended particulate material（SPM） and negative correlation to depth indicated that Se（IV） tended to be released from the high density particulate matter. Instead, Se（VI） content did not significantly relate to SPM since it generally formed inner-sphere complex to iron hydroxide. Se（IV） content negatively varied to salinity and largely depended on the freshwater dilution and physical mixing. While, Se（VI） level deviated from the dilution line due to the in situ biogeochemical process such as removal via phytoplankton uptake and inputs via organic matter regeneration. As the essential element, Se（IV） was confirmed more bioavailable to phytoplankton growth than Se（VI）, and moreover, seemed to be more related to phosphorus than to nitrogen.展开更多
Iron in seawater is an essential trace metal for phytoplankton that plays an important role in the marine carbon cycle. But most studies focused on oceanic iron fertilization in high nutrient low chlorophyll （HNLC） ...Iron in seawater is an essential trace metal for phytoplankton that plays an important role in the marine carbon cycle. But most studies focused on oceanic iron fertilization in high nutrient low chlorophyll （HNLC） seawaters. A study of inorganic carbon （IC） forms and its influencing factors was presented in Liaodong Gulf sediments, and especially the influence of iron was discussed in detail. Inorganic carbon in Liaodong Gulf sediments was divided into five forms： NaCl, NH3·H2O, NaOH, NH2OH·HCl and HCl. The concentration of NaCl and NaOH forms were similar and they only occupied the minority of total inorganic carbon （TIC）. However, NH3 ·H2O, NH2OH · HCl and HCl forms were the principal forms of TIC and accounted for more than 80% of TIC. Especially, the percentage of NH3·H2O form was much higher than that in the Changjiang River Estuary and Jiaozhou Bay sediments. All forms of inorganic carbon were influenced by organic carbon, pore water, iron, pH, redox potential （Eh） and sulfur potential（Es） in sediments, moreover, the influences had different characteristics for different IC forms. However, the redox reactions of iron affected mainly active IC forms. Iron had little effect on NH2OH· HCl and HCl forms of IC which were influenced mainly by pH. Iron had a stronger influence on NaCl, NaOH and NH3· H2O forms of IC ; the influence of Fe^2＋ was higher than Fe^3＋ and its effect on NH3 ·H2O form was stronger than on NaCl and NaOH forms.展开更多
文摘Phosphorus is a key element and plays an important role in global biogeochemical cycles. The evolution of sedimentary environment is also influenced by phosphorus concentrations and fractions as well as phosphate sorption characteristics of the marine sediments. The geochemical characteristics of phosphorus and their environmental records were presented in Jiaozhou Bay sediments. Profiles of different forms of phosphorus were measured as well as the roles and vertical distributions of phosphorus forms in response to sedimentary environment changes were investigated. The results showed that inorganic phosphorus （IP） was the major fraction of total phosphorus （TP）; phosphorus which is bound to calcium, iron and occluded phosphorus, as well as the exchangeable phosphorus were the main forms of IP, especially calcium - phosphorus, including detrital carbonate-bound phosphorus （Det- P） and authigenic apatite-bound phosphorus （ACa- P）, are the uppermost constituent of IP in Jiaozhou Bay sediments. Moreover, the lead-210 chronology technology was employed to estimate how much phosphorus was buried ultimately in sediments. And the research showed that the impacts of human activities have increased remarkably in recent years especially between the 1980s and 2000. According to research, the development of Jiaozhou Bay environment in the past hundred years can be divided into three stages ： （ 1 ） before the 1980s characterized by the relatively low sedimentation rate, weak land-derived phosphorus inputs and low anthropogenic impacts; （2） from the 1980s to around 2000, accelerating in the 1990s, during which high sedimentation rates, high phosphorus abundance and burial fluxes due to the severe human activities impacted on the whole environmental system ; （ 3 ） after 2000, the period of the improvement of environment, the whole system has been improved including the decreasing sedimentation rates, concentration and the burial fluxes of phosphorus.
基金supported by the National Key Project for Basic Research of China (No. 2007CB407305)the Fund for Creative Research Groups by NSFC (No.40821004)the Hundred Talents Project of Chinese Academy of Sciences
文摘Sixteen polycyclic aromatic hydrocarbons （PAHs） and 28 polychlorinated biphenyls （PCBs） were measured at a 2-cm interval in a core sample from the middle of the southern Yellow Sea for elucidating their historical variations in inflow and sources. The chronology was obtained using the ^210Pb method. PAHs concentrations decreased generally with depth and two climax values occurred in 14-16 cm and 20-22 cm layers, demonstrating that the production and usage of PAHs might reach peaks in the periods of 1956-1962 and 1938-1944. The booming economy and the navy battles of the Second World War might explain why the higher levels were detected in the two layers. The result of principal component analysis （PCA） revealed that PAHs were primarily owing to the combustion product. Down-cored variation of PCB concentrations was complex. Higher concentrations besides the two peaks being the same as PAHs were detected from 4 to 8 cm, depositing from 1980 to 1992, which probably resulted from the disposal of the out-dated PCB-containing equipment. The average Cl percentage of PCBs detected was similar to that of the mixture of Aroclor 1254 and 1242, suggesting they might origin from the dielectrical and heat-transfer fluid. The total organic carbon （TOC） content played a prevalent role in the adsorption of high molecular weight PAHs （≥ring）, while no obvious relationship among total PCBs, the concentration of congeners, and TOC was found.
基金The Joint Fund between Natural Science Foundation of China and Shandong Province under contract No.U1606404the National Basic Research Program(973 Program)of China under contract Nos 2015CB452901 and 2015CB452902+1 种基金the National Key Research and Development Plan Sino-Australian Centre for Healthy Coasts under contract No.2016YFE0101500the Program for Aoshan Excellent Scholars of Qingdao National Laboratory for Marine Science and Technology of China under contract No.2015ASTP-OS13
文摘The Jiaozhou Bay is characterized by heavy eutrophication that is associated with intensive anthropogenic activities. Four core sediments from the Jiaozhou Bay are analyzed using bulk technologies, including sedimentary total organic carbon（TOC）, total nitrogen（TN）, the stable carbon（δ13C） and nitrogen（δ15 N） isotopic composition to obtain the comprehensive understanding of the source and composition of sedimentary organic matter and further shed light on the environmental changes of the Jiaozhou Bay on a centennial time scale.Results suggest that the TOC and TN concentrations increase in the upper core, having indicated a probable eutrophication process since the 1920 s in the inner bay and the 2000 s in the bay mouth. The TOC and TN concentrations outside the bay have also changed since 1916 owing to the variation of terrigenous input.Considering TOC/TN ratio, δ13 C and δ15 N, it can be concluded there is a mixture of terrigenous and marine organic matter sources in the study area. A simple two end-member（terrigenous and marine） mixing model usingδ13 C indicats that 45%–79% of TOC in the Jiaozhou Bay is from the marine source. The environmental changes of the Jiaozhou Bay are recorded by geochemical proxies, which are influenced by the intensive anthropogenic activities（e.g., extensive use of fertilizers, and discharge of sewage） and climate changes（e.g., rainfall）.
基金This study was supported by the Qingdao Special Program for Leading Scientists under contract No.04-3-JJ-03the Knowledge Innovation Program of the Chinese Academy of Sciences under contract No.KZCX1-SW-01-08the“100 Talents Project”of the Chinese Academy of Sciences and the National Science Foundation for Outstanding Young Scientists of China under contract No.49925614.
文摘The results of field observation carried out in May 2003 were used to examine pH and total alkalinity behaviors in the Changjiang Estuary. It was showed that pH and total alkalinity took on clear spatial variations in values with the minima in the low salinity region. Like salinity, transect distributions of pH and total alkalinity （TA） in a downriver direction had a sharp gradient each. These gradients appeared in such a sequence that the TA gradient was earlier than salinity and pH gradients, and the salinity gradient was earlier than the pH gradient. These distribution characteristics seemed to be strongly influenced by the mixing process of freshwater and seawater, for both pH and total alkalinity had significant linear relationships with salinity and temperature. For pH, phytoplankton activities also had a significant impact upon its spatial distribution. During a period of 48 h, pH and total alkalinity changed within wide ranges for every layer of the two anchor stations, namely, Stas 13 and 20, which were located at the mixed water mass and seawater mass, respectively. For both Stas 13 and 20, pH and TA fluctuation of every layer could be very wide during a 4 h period. As a whole, the data of the two anchor stations showed that neither variations in salinity and temperature nor phytoplankton activities were the main factors strongly influencing the total alkalinity temporal variability on a small time scale. The data of Sta. 20 implied that both salinity variation and phytoplankton activities had a significant influence on pH temporal variability, but the same conclusion could not be drawn from the data of Sta. 13.
基金The National Natural Science Foundation of China for Creative Research Groups under contract No.41121064the National Natural Science Foundation of China under contract No.41306055+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences under contract No.XDA05030402the National Basic Research Program of China(973 Program)under contract No.2011CB403602
文摘Dissolved selenium in the Changjiang（Yangtze） Estuary and its adjacent waters was determined by hydride generation atomic fluorescence spectrometry to elucidate the source, behavior in estuary, adsorption-desorption process and biological role. In surface water, Se（IV） concentration ranged 0.05–1.14 nmol/L and Se（VI） concentration varied 0.01–1.20 nmol/L, with the means of 0.76 and 0.49 nmol/L, respectively. In bottom water, Se（IV） content varied 0.03–0.27 nmol/L and Se（VI） content ranged 0.04–0.85 nmol/L, with the averages of 0.10 and 0.40 nmol/L, respectively. High level of Se（IV） was observed near the shore with a significant decrease towards the open sea, suggesting the continental input from the adjacent rivers. Large value of Se（VI） was found in bottom water, reflecting the release from suspended sediment. Besides, high value appeared in the same latitude of the Changjiang Estuary and Hangzhou Bay illustrated the effect of lateral mixing and the long-distance transport of selenium. Se（VI）, more soluble, occupied higher percentage in aqueous environment. The presence of Se（IV） resulted from the degradation of residue and the reduction of Se（VI） under anaerobic condition. The positive relationship to suspended particulate material（SPM） and negative correlation to depth indicated that Se（IV） tended to be released from the high density particulate matter. Instead, Se（VI） content did not significantly relate to SPM since it generally formed inner-sphere complex to iron hydroxide. Se（IV） content negatively varied to salinity and largely depended on the freshwater dilution and physical mixing. While, Se（VI） level deviated from the dilution line due to the in situ biogeochemical process such as removal via phytoplankton uptake and inputs via organic matter regeneration. As the essential element, Se（IV） was confirmed more bioavailable to phytoplankton growth than Se（VI）, and moreover, seemed to be more related to phosphorus than to nitrogen.
文摘Iron in seawater is an essential trace metal for phytoplankton that plays an important role in the marine carbon cycle. But most studies focused on oceanic iron fertilization in high nutrient low chlorophyll （HNLC） seawaters. A study of inorganic carbon （IC） forms and its influencing factors was presented in Liaodong Gulf sediments, and especially the influence of iron was discussed in detail. Inorganic carbon in Liaodong Gulf sediments was divided into five forms： NaCl, NH3·H2O, NaOH, NH2OH·HCl and HCl. The concentration of NaCl and NaOH forms were similar and they only occupied the minority of total inorganic carbon （TIC）. However, NH3 ·H2O, NH2OH · HCl and HCl forms were the principal forms of TIC and accounted for more than 80% of TIC. Especially, the percentage of NH3·H2O form was much higher than that in the Changjiang River Estuary and Jiaozhou Bay sediments. All forms of inorganic carbon were influenced by organic carbon, pore water, iron, pH, redox potential （Eh） and sulfur potential（Es） in sediments, moreover, the influences had different characteristics for different IC forms. However, the redox reactions of iron affected mainly active IC forms. Iron had little effect on NH2OH· HCl and HCl forms of IC which were influenced mainly by pH. Iron had a stronger influence on NaCl, NaOH and NH3· H2O forms of IC ; the influence of Fe^2＋ was higher than Fe^3＋ and its effect on NH3 ·H2O form was stronger than on NaCl and NaOH forms.
