For the past 20 years, numerous studies have been carried out on the application of equilibrium partitioning approach （EqPA） for the derivation of sediment quality guidelines （SQGs）. However, for metals, few Equil...For the past 20 years, numerous studies have been carried out on the application of equilibrium partitioning approach （EqPA） for the derivation of sediment quality guidelines （SQGs）. However, for metals, few Equilibrium-partitioning- based numerical SQGs have been developed or are currently available because of the confounding factors mediating the bioavailability of metals. A study was conducted at Dianchi Lake, which is a heavily eutrophicated lake on the Yunnan- Guizhou Plateau, China with the focus on the measurement of partitioning coefficient （Kp） and SQGs derivation and normalization to acid volatile sulfide （AVS）, fine material, and organic carbon. Using new normalization methods, SQGs were formulated for seven metals including copper, zinc, lead, cadmium, chromium, mercury, and arsenic in Dianchi Lake. In Dianchi Lake sediments, the fine material contributed 25.4%-36.0% to the SQG values, with the largest contribution to the SQG value of mercury; AVS contributed 2.9%-75.0% to the SQG values, with the largest contribution to the SQG value of cadmium. This indicated that the fine material and the AVS were the most important controlling factors to the bioavailability of mercury and caximium, respectively. The contribution of total organic carbon （TOC） to the SQG values of copper and leaxi was 3.8% and 7.1%, respectively, indicating that at relatively lower concentrations, the contribution of TOC was not significant. In addition to normalization methods, appropriate procedures for the application of EqPA including sample collection, storage, and analysis are also essential to improve the reliability of SQGs. The normalized Dianchi Lake SQGs were higher than most of the empirically based SQGs developed in North America, but lower than Hong Kong interim SQGs except for cadmium and arsenic. The differences could be attributed to the approaches used for derivation of SQGs and the water quality criteria adopted and the differences in the physical and chemical characteristics of the sediments.展开更多
Spatial variations in lake sediments are a product of their depositional heterogeneities.To better correlate synchronous strata in Huangqihai Lake,two sections were excavated from the lake-center and the lake-shore.Th...Spatial variations in lake sediments are a product of their depositional heterogeneities.To better correlate synchronous strata in Huangqihai Lake,two sections were excavated from the lake-center and the lake-shore.The study involved detailed lithology,mineralogy,and rock magnetic analysis.The results show that the frequency-dependent susceptibility,which is related to the content of super-paramagnetic minerals,is relatively easy to contrast between the two sections.However,mass susceptibility and saturation isothermal remanence,which are related to the content of total magnetic minerals,are difficult to contrast.A possible reason for this difference is that small-particle super-paramagnetic minerals are formed mainly during pedogenic processes,which correlates well with climate change and avoids the effects of local factors when corrections are made at the whole-lake scale.Both sections can be divided into three stages,which appear to be well correlated with previous results obtained through other environmental proxies.展开更多
基金Project supported by the State Key Laboratory of Soil and Sustainable Agriculture, China (No. 5022505)the National Natural Science Foundation of China (No. 40771128)
文摘For the past 20 years, numerous studies have been carried out on the application of equilibrium partitioning approach （EqPA） for the derivation of sediment quality guidelines （SQGs）. However, for metals, few Equilibrium-partitioning- based numerical SQGs have been developed or are currently available because of the confounding factors mediating the bioavailability of metals. A study was conducted at Dianchi Lake, which is a heavily eutrophicated lake on the Yunnan- Guizhou Plateau, China with the focus on the measurement of partitioning coefficient （Kp） and SQGs derivation and normalization to acid volatile sulfide （AVS）, fine material, and organic carbon. Using new normalization methods, SQGs were formulated for seven metals including copper, zinc, lead, cadmium, chromium, mercury, and arsenic in Dianchi Lake. In Dianchi Lake sediments, the fine material contributed 25.4%-36.0% to the SQG values, with the largest contribution to the SQG value of mercury; AVS contributed 2.9%-75.0% to the SQG values, with the largest contribution to the SQG value of cadmium. This indicated that the fine material and the AVS were the most important controlling factors to the bioavailability of mercury and caximium, respectively. The contribution of total organic carbon （TOC） to the SQG values of copper and leaxi was 3.8% and 7.1%, respectively, indicating that at relatively lower concentrations, the contribution of TOC was not significant. In addition to normalization methods, appropriate procedures for the application of EqPA including sample collection, storage, and analysis are also essential to improve the reliability of SQGs. The normalized Dianchi Lake SQGs were higher than most of the empirically based SQGs developed in North America, but lower than Hong Kong interim SQGs except for cadmium and arsenic. The differences could be attributed to the approaches used for derivation of SQGs and the water quality criteria adopted and the differences in the physical and chemical characteristics of the sediments.
基金supported by Basic Outlay of Scientific Research Work from the Ministry of Science and Technology (Grant No. J1001 and J1210)the China Geological Survey Project (Grant No. 1212010911027 and 1212011087116)
文摘Spatial variations in lake sediments are a product of their depositional heterogeneities.To better correlate synchronous strata in Huangqihai Lake,two sections were excavated from the lake-center and the lake-shore.The study involved detailed lithology,mineralogy,and rock magnetic analysis.The results show that the frequency-dependent susceptibility,which is related to the content of super-paramagnetic minerals,is relatively easy to contrast between the two sections.However,mass susceptibility and saturation isothermal remanence,which are related to the content of total magnetic minerals,are difficult to contrast.A possible reason for this difference is that small-particle super-paramagnetic minerals are formed mainly during pedogenic processes,which correlates well with climate change and avoids the effects of local factors when corrections are made at the whole-lake scale.Both sections can be divided into three stages,which appear to be well correlated with previous results obtained through other environmental proxies.
