The arsenic(As)release from sediments in great lakes is affected by various factors.In this study,the characteristics of As release fromsediments was investigated,and the As sources and sinks with the strengths in sed...The arsenic(As)release from sediments in great lakes is affected by various factors.In this study,the characteristics of As release fromsediments was investigated,and the As sources and sinks with the strengths in sediments from different areas(grass-type,algae-type,and grass-algae alternation areas)in great shallow lakes(Taihu Lake,China)were analyzed,and the influence of P competition in the process of As release was also studied.The results showed that changing trend of the values of equilibrium As concentration in sediments were consistent with the regional changes(0 to 28.12μg/L),and the sediments from algaetype areas had the higher values.The sediments from western lake and northwest lake bay were a strong As and a weak P source,and the north lake bay had the opposite trend of these two regions.Intense P source competition with As from the sediments occurred in algae-type areas.The grass-type areas had strong As and P retention capacities,indicating a sink role of sediment with high As and P sorption capacities.The degree of As and P saturation had similar trend in sediments,and the grass-type areas had the higher values,18.3%-21.4%and 15.31%-20.34%,respectively.Contribution analysis results showed that most of As release contribution was from the bottom(30-50 cm)sediments,and the surface(0-10 cm)sediments from algae-type areas contributed more to the overlying water than other region.展开更多
Total contents of metals in soil and sediments on the Tibetan Plateau of China have been widely analyzed,but existing information is insufficient to effectively evaluate metal ecological risk because of a lack of meta...Total contents of metals in soil and sediments on the Tibetan Plateau of China have been widely analyzed,but existing information is insufficient to effectively evaluate metal ecological risk because of a lack of metal bioavailability data.In this study,distribution,potential risk,mobility and bioavailability of metals in sediments of Lake Yamdrok Basin in Tibet of China were explored by combined use of total digestion,sequential extraction and the diffusive gradient in thin-films(DGT).Average concentrations of Cr,Ni,Cu,Zn,As,Cd and Pb in surface sediments were 31.25,30.31,22.00,45.04,31.32,0.13 and 13.39 mg/kg,respectively.Higher levels of metals were found near the inflowing rivers.Residual form was dominant in Cr,Ni,Zn,Cd and Pb,and reducible form was dominant in As and Cd.Metals in surface sediments showed a low enrichment degree overall,but Cd and As had higher ecological risk levels than the other metals.Furthermore,there was a larger average proportion of exchangeable form of As(20.4%)and Cd(9.0%)than the other metals(1.7%-3.3%),implying their higher mobility and release risk.Average DGT-labile concentrations of Cr,Ni,Cu,Zn,As,Cd and Pb were 0.5,4.5,0.7,25.1,60.0,0.22 and 1.0μg/L,respectively.The DGT-labile As was significantly correlated with extractable As forms(p<0.01),suggesting that extractable As in sediments acts as a"mobile pool"for bioavailable As.These results suggest potential risks of As and Cd,especially As,deserve further attention in Lake Yamdrok Basin.展开更多
The arsenate（As（V）） biotransformation by Microcystis aeruginosa in a medium with different concentrations of nitrogen（N） and phosphorus（P） has been studied under laboratory conditions. When 15 μg/L As（V） wa...The arsenate（As（V）） biotransformation by Microcystis aeruginosa in a medium with different concentrations of nitrogen（N） and phosphorus（P） has been studied under laboratory conditions. When 15 μg/L As（V） was added, N and P in the medium showed effective regulation on arsenic（As） metabolism in M. aeruginosa, resulting in significant differences in the algal growth among different N and P treatments. Under 0.2 mg/L P treatment, increases in N concentration（4–20 mg/L） significantly stimulated the cell growth and therefore indirectly enhanced the production of dimethylarsinic acid（DMA）, the main As metabolite, accounting for 71%–79% of the total As in the medium. Meanwhile, 10–20 mg/L N treatments accelerated the ability of As metabolization by M. aeruginosa, leading to higher contents of DMA per cell.However, As（V） uptake by M. aeruginosa was significantly impeded by 0.5–1.0 mg/L P treatment,resulting in smaller rates of As transformation in M. aeruginosa as well as lower contents of As metabolites in the medium. Our data demonstrated that As（V） transformation by M. aeruginosa was significantly accelerated by increasing N levels, while it was inhibited by increasing P levels. Overall, both P and N play key roles in As（V） biotransformation processes.展开更多
基金supported by the National Natural Science Foundation(Nos.52000024 and 41907335)the Natural Science Foundation of Shanghai(No.23ZR1400700).
文摘The arsenic(As)release from sediments in great lakes is affected by various factors.In this study,the characteristics of As release fromsediments was investigated,and the As sources and sinks with the strengths in sediments from different areas(grass-type,algae-type,and grass-algae alternation areas)in great shallow lakes(Taihu Lake,China)were analyzed,and the influence of P competition in the process of As release was also studied.The results showed that changing trend of the values of equilibrium As concentration in sediments were consistent with the regional changes(0 to 28.12μg/L),and the sediments from algaetype areas had the higher values.The sediments from western lake and northwest lake bay were a strong As and a weak P source,and the north lake bay had the opposite trend of these two regions.Intense P source competition with As from the sediments occurred in algae-type areas.The grass-type areas had strong As and P retention capacities,indicating a sink role of sediment with high As and P sorption capacities.The degree of As and P saturation had similar trend in sediments,and the grass-type areas had the higher values,18.3%-21.4%and 15.31%-20.34%,respectively.Contribution analysis results showed that most of As release contribution was from the bottom(30-50 cm)sediments,and the surface(0-10 cm)sediments from algae-type areas contributed more to the overlying water than other region.
基金supported by the National Natural Science Foundation of China(No.42202018027)。
文摘Total contents of metals in soil and sediments on the Tibetan Plateau of China have been widely analyzed,but existing information is insufficient to effectively evaluate metal ecological risk because of a lack of metal bioavailability data.In this study,distribution,potential risk,mobility and bioavailability of metals in sediments of Lake Yamdrok Basin in Tibet of China were explored by combined use of total digestion,sequential extraction and the diffusive gradient in thin-films(DGT).Average concentrations of Cr,Ni,Cu,Zn,As,Cd and Pb in surface sediments were 31.25,30.31,22.00,45.04,31.32,0.13 and 13.39 mg/kg,respectively.Higher levels of metals were found near the inflowing rivers.Residual form was dominant in Cr,Ni,Zn,Cd and Pb,and reducible form was dominant in As and Cd.Metals in surface sediments showed a low enrichment degree overall,but Cd and As had higher ecological risk levels than the other metals.Furthermore,there was a larger average proportion of exchangeable form of As(20.4%)and Cd(9.0%)than the other metals(1.7%-3.3%),implying their higher mobility and release risk.Average DGT-labile concentrations of Cr,Ni,Cu,Zn,As,Cd and Pb were 0.5,4.5,0.7,25.1,60.0,0.22 and 1.0μg/L,respectively.The DGT-labile As was significantly correlated with extractable As forms(p<0.01),suggesting that extractable As in sediments acts as a"mobile pool"for bioavailable As.These results suggest potential risks of As and Cd,especially As,deserve further attention in Lake Yamdrok Basin.
基金supported by the National Nature Science Foundation of China (Nos. 21277136 and 21577138)
文摘The arsenate（As（V）） biotransformation by Microcystis aeruginosa in a medium with different concentrations of nitrogen（N） and phosphorus（P） has been studied under laboratory conditions. When 15 μg/L As（V） was added, N and P in the medium showed effective regulation on arsenic（As） metabolism in M. aeruginosa, resulting in significant differences in the algal growth among different N and P treatments. Under 0.2 mg/L P treatment, increases in N concentration（4–20 mg/L） significantly stimulated the cell growth and therefore indirectly enhanced the production of dimethylarsinic acid（DMA）, the main As metabolite, accounting for 71%–79% of the total As in the medium. Meanwhile, 10–20 mg/L N treatments accelerated the ability of As metabolization by M. aeruginosa, leading to higher contents of DMA per cell.However, As（V） uptake by M. aeruginosa was significantly impeded by 0.5–1.0 mg/L P treatment,resulting in smaller rates of As transformation in M. aeruginosa as well as lower contents of As metabolites in the medium. Our data demonstrated that As（V） transformation by M. aeruginosa was significantly accelerated by increasing N levels, while it was inhibited by increasing P levels. Overall, both P and N play key roles in As（V） biotransformation processes.
