The turnover of phosphorus （P） in lake sediments, a major cause of eutrophication and subsequent deterioration of water quality, is in need of deep understanding. In this study, effects of resuspension on P release ...The turnover of phosphorus （P） in lake sediments, a major cause of eutrophication and subsequent deterioration of water quality, is in need of deep understanding. In this study, effects of resuspension on P release were studied in cylindrical microcosms with Yshape apparatus. The results indicated that there was a positive correlation between flux of suspended substance across sediment-water interface （Fss） and the wind speed, and an increasing Fss during each wind process followed by a steady state. The maximal Fss under fight, moderate, and strong wind conditions were 299.9±41.1,573.4±61.7, and 2093.8±215.7 g/m^2, respectively. However, flux of P across sediment-water interface （Fp） did not follow a similar pattern as Fss responding to wind intensity, which increased and reached the maximum in initial 120 rain for fight wind, then decreased gradually, with maximal flux of 9.4±1.9 mg/m^2. A rapid increase of Fp at the first 30 rain was observed under moderate wind, with maximal flux of 11.2±0.6 mg/m^2. Surprisingly, strong wind caused less Fp than under light and moderate wind conditions with maximal flux of 3.5±0.9 mg/m^2. Fss in water column declined obviously during the sedimentation process after winds, but Fp varied with wind regime. No obvious difference was detected on Fp after 8 h sedimentation process, compared with the initial value, which means little redundant P left in the water column after winds.展开更多
A laboratory experiment was carried out through a six-month incubation of undredged (control) and dredged cores to study the effect of sediment dredging on phosphorus (P) release from the sediment in the Taihu Lake.Du...A laboratory experiment was carried out through a six-month incubation of undredged (control) and dredged cores to study the effect of sediment dredging on phosphorus (P) release from the sediment in the Taihu Lake.During the experiment,dredging the upper 30 cm layer could efficiently reduce the interstitial PO_4^(3-)-P concentration and different P forms in the sediment.The P fluxes of the undredged and dredged cores ranged from-5.1 to 3047.6 and-60.7 to 14.4μg m^(-2) d^(-1),respectively.The fluxes of the dredged cores were generally lower than those of the control.Differences in the fluxes between the dredged and undredged cores were statistically significant (P<0.05) from March to June 2006. The sediment P in the dredged cores had a lower release potential than that in the control.Dredging can be considered as a useful measure for rehabilitating the aquatic ecosystem after the external P loading in the Taihu Lake catchment was efficiently reduced.展开更多
To understand the geochemical characteristics of iron and sulfur and the extent of iron-sulfide minerals in-uencing heavy metal behaviour in metal-polluted sediments of Taihu Lake,two sites,in Meiliang Bay(ML) and Wul...To understand the geochemical characteristics of iron and sulfur and the extent of iron-sulfide minerals in-uencing heavy metal behaviour in metal-polluted sediments of Taihu Lake,two sites,in Meiliang Bay(ML) and Wuli Lake(WL) ,were selected to study the fractionation of iron,sulfur and related heavy metals. There were relatively high concentrations of Fe2+ and low concentrations of total S2-in porewaters,indicating that conditions in these sediments favored iron reduction. The concentrations of acid volatile sulfides in sediments were 1.9-9.6 μmol g-1 at ML and 1.0-11.7 μmol g-1 at WL,both in the range of values detected in unpolluted lakes. Pyrite-S was 10.2-49.4 μmol g-1 at ML and 10.3- 33.0 μmol g-1 at WL,accounting for more than 69% of the reduced inorganic sulfur at both sites. The low degree of sulphidization(< 14%) and pyritization(< 10%) indicate that sulfate may be the limiting factor for pyrite formation. The extractability of Mn,Cu,Pb,Zn,Ni,and Cr in sediments all suggest that sulfides are not the major binding phase for these metals during early diagenesis. Sulfur may play a modest role in the geochemistry of iron and traced metals in the sediments.展开更多
Time series bioaccumulation of rare earth elements (REEs) in field-grown wheat with and without a dressing of extraneous REE fertilizer at different growth stages and fractionation of REEs during their transport in a ...Time series bioaccumulation of rare earth elements (REEs) in field-grown wheat with and without a dressing of extraneous REE fertilizer at different growth stages and fractionation of REEs during their transport in a soil-wheat system were determined. Time-dependent accumulation of extraneous REEs was found in different parts of wheat. An upward transport of extraneous REEs from roots to shoots under a soil dressing and a downward transport from leaves to roots with a foliar dressing were also observed. Moreover, fractionation of REEs occurred in the soil-wheat system. Compared to the host soil a positive Eu anomaly in the stems and grains as well as heavy REE enrichment in the grains were found. The ability of the different wheat organs to fractionate Eu from the REE series was ranked in the order of stems ≥ grains > leaves > roots.展开更多
基金Project supported by the National Natural Science Foundation of China(No. 20577053) the Pilot Project of Knowledge Innovation Program of Chinese Academy of Sciences(No. KZCX3-SW-348)the Hi-Tech Research and Development Program(863)of China(No.200560101005).
文摘The turnover of phosphorus （P） in lake sediments, a major cause of eutrophication and subsequent deterioration of water quality, is in need of deep understanding. In this study, effects of resuspension on P release were studied in cylindrical microcosms with Yshape apparatus. The results indicated that there was a positive correlation between flux of suspended substance across sediment-water interface （Fss） and the wind speed, and an increasing Fss during each wind process followed by a steady state. The maximal Fss under fight, moderate, and strong wind conditions were 299.9±41.1,573.4±61.7, and 2093.8±215.7 g/m^2, respectively. However, flux of P across sediment-water interface （Fp） did not follow a similar pattern as Fss responding to wind intensity, which increased and reached the maximum in initial 120 rain for fight wind, then decreased gradually, with maximal flux of 9.4±1.9 mg/m^2. A rapid increase of Fp at the first 30 rain was observed under moderate wind, with maximal flux of 11.2±0.6 mg/m^2. Surprisingly, strong wind caused less Fp than under light and moderate wind conditions with maximal flux of 3.5±0.9 mg/m^2. Fss in water column declined obviously during the sedimentation process after winds, but Fp varied with wind regime. No obvious difference was detected on Fp after 8 h sedimentation process, compared with the initial value, which means little redundant P left in the water column after winds.
基金Project supported by the Knowledge Innovation Project of the Chinese Academy of Sciences (No.KZCX3-SW-348)the National Natural Science Foundation of China (Nos.20577053 and 40730528)the National High Technology Research and Development Program (863 Program) of China (No.2005AA60101005).
文摘A laboratory experiment was carried out through a six-month incubation of undredged (control) and dredged cores to study the effect of sediment dredging on phosphorus (P) release from the sediment in the Taihu Lake.During the experiment,dredging the upper 30 cm layer could efficiently reduce the interstitial PO_4^(3-)-P concentration and different P forms in the sediment.The P fluxes of the undredged and dredged cores ranged from-5.1 to 3047.6 and-60.7 to 14.4μg m^(-2) d^(-1),respectively.The fluxes of the dredged cores were generally lower than those of the control.Differences in the fluxes between the dredged and undredged cores were statistically significant (P<0.05) from March to June 2006. The sediment P in the dredged cores had a lower release potential than that in the control.Dredging can be considered as a useful measure for rehabilitating the aquatic ecosystem after the external P loading in the Taihu Lake catchment was efficiently reduced.
基金the National Natural Science Foundation of China (No.40730528)the National High Technology Research and Development Program (863 Program) of China (No.2007AA06Z411)the Social Development Plan of Jiangsu Province (No.BS2007161).
文摘To understand the geochemical characteristics of iron and sulfur and the extent of iron-sulfide minerals in-uencing heavy metal behaviour in metal-polluted sediments of Taihu Lake,two sites,in Meiliang Bay(ML) and Wuli Lake(WL) ,were selected to study the fractionation of iron,sulfur and related heavy metals. There were relatively high concentrations of Fe2+ and low concentrations of total S2-in porewaters,indicating that conditions in these sediments favored iron reduction. The concentrations of acid volatile sulfides in sediments were 1.9-9.6 μmol g-1 at ML and 1.0-11.7 μmol g-1 at WL,both in the range of values detected in unpolluted lakes. Pyrite-S was 10.2-49.4 μmol g-1 at ML and 10.3- 33.0 μmol g-1 at WL,accounting for more than 69% of the reduced inorganic sulfur at both sites. The low degree of sulphidization(< 14%) and pyritization(< 10%) indicate that sulfate may be the limiting factor for pyrite formation. The extractability of Mn,Cu,Pb,Zn,Ni,and Cr in sediments all suggest that sulfides are not the major binding phase for these metals during early diagenesis. Sulfur may play a modest role in the geochemistry of iron and traced metals in the sediments.
基金Project supported by the National Natural Science Foundation of China (Nos. 40232022 and 40571146).
文摘Time series bioaccumulation of rare earth elements (REEs) in field-grown wheat with and without a dressing of extraneous REE fertilizer at different growth stages and fractionation of REEs during their transport in a soil-wheat system were determined. Time-dependent accumulation of extraneous REEs was found in different parts of wheat. An upward transport of extraneous REEs from roots to shoots under a soil dressing and a downward transport from leaves to roots with a foliar dressing were also observed. Moreover, fractionation of REEs occurred in the soil-wheat system. Compared to the host soil a positive Eu anomaly in the stems and grains as well as heavy REE enrichment in the grains were found. The ability of the different wheat organs to fractionate Eu from the REE series was ranked in the order of stems ≥ grains > leaves > roots.
