Heavy metal contamination of soils,derived from sewage irrigation,mining and inappropriate utilization of various agrochemicals and pesticides,and so on,has been of wide concern in the last several decades.The Shenyan...Heavy metal contamination of soils,derived from sewage irrigation,mining and inappropriate utilization of various agrochemicals and pesticides,and so on,has been of wide concern in the last several decades.The Shenyang Zhangshi Irrigation Area(SZIA) in China is a representative area of heavy metal contamination of soils resulting from sewage irrigation for about 30 years.This study investigated the spatial distribution and temporal variation of soil cadmium(Cd) and copper(Cu) contamination in the SZIA.The soil samples were collected from the SZIA in 1990 and 2004;Cd and Cu in soils was analyzed and then the spatial distribution and temporal variation of Cd and Cu in soils were modeled using Kriging methods.The results show that long-term sewage irrigation had caused serious Cd and Cu contamination in soils.The mean and the maximum of soil Cd are markedly higher than the levels in second grade standard soil(LSGSS) in China,and the maximum of soil Cu is close to the LSGSS in China in 2004 and is more than the LSGSS in China in 1990.The contamination magnitude of soil Cd and the soil extent of Cd contamination had evidently increased since sewage irrigation ceased in 1992.The contamination magnitude of soil Cu and the soil extent of Cu contamination had evidently increased in topsoil,but obviously decresed in subsoil.The soil contamination of Cd and Cu was mainly related to Cd and Cu reactivation of contaminated sediments in Shenyang Xi River and the import of Cd and Cu during irrigation.The eluviation of Cd and Cu in contaminated topsoil with rainfall and irrigation water was another factor of temporal-spatial variability of Cd and Cu contamination in soils.展开更多
The modified three-step sequential extraction procedure proposed by the BCR was used to predict Pb and Cd fractional distribution in sewage sludge and tomato soil amended with sludge compost. There was no significant ...The modified three-step sequential extraction procedure proposed by the BCR was used to predict Pb and Cd fractional distribution in sewage sludge and tomato soil amended with sludge compost. There was no significant increasing of Pb and Cd contents in the soil with sludge application as compared with that in the reference soil. The Pb contents were much lower for the soil samples than for the National Soil Standards of Environmental Quality, but Cd contents in soil were much more than background mean Cd contents. Pb content in soil fractions was followed with residual Pb 〉 reducible Pb 〉 exchangeable and weak acid soluble Pb〉 oxidizable Pb. In all soil samples, the partitioning of Cd had the same extractability in the first two steps of the procedure and the residual fraction. Only a small fraction or almost zero extractability was observed at the oxidation step for Pb and Cd.展开更多
Determining the appropriate soil cadmium(Cd)criteria for vegetable production is important for ensuring that the Cd concentrations of the vegetables meet food safety standards.The soil extractable Cd criteria for vege...Determining the appropriate soil cadmium(Cd)criteria for vegetable production is important for ensuring that the Cd concentrations of the vegetables meet food safety standards.The soil extractable Cd criteria for vegetable production are also essential for both food safety and environmental management,especially in areas with a high natural background level.In the present study,soil total and extractable Cd criteria were derived using the approach of species sensitivity distribution integrated with soil aging and bioavailability as affected by soil properties.A dataset of 90 vegetable species planted in different soils was compiled by screening the published in literature in five bibliographic databases using designated search strings.The empirical soil-plant transfer model was applied to normalize the bioaccumulation data.After normalization,the intra-species variability was reduced by 18.3 to 84.4%.The soil Cd concentration that would protect 95%(HC_(5))of the species was estimated by species sensitivity distribution curves that were fitted by the Burr III function.The soil Cd criteria derived from the added approach for risk assessment were proposed as continuous criteria based on a combination of organic carbon and pH in the soil.Criteria for total Cd and EDTA-extractable Cd in the soil ranged from 0.23 to 0.61 mg kg^(-1)and from 0.09 to 0.25 mg kg^(-1),respectively.Field experimental data were used to validate the applicability and validity of these criteria.Most of the predicted HC5 values in the field experimental sites were below the 1:1 line.These results provide a scientific basis for soil Cd criteria for vegetable production that will ensure food safety.展开更多
This study assesses the level of contamination of Hg in farmland soils along the irrigating channel down-stream from Guizhou Organic Chemical Factory (GOCF),where metallic mercury is used as a catalyst to produce acet...This study assesses the level of contamination of Hg in farmland soils along the irrigating channel down-stream from Guizhou Organic Chemical Factory (GOCF),where metallic mercury is used as a catalyst to produce acetic acid. The total input of mercury into the environment,as announced by GOCF,is 140 t in the past 30 years (1971-2000). Sampling sites were chosen based on the distance from the source of pollution—the chemical factory. A total of 39 samples were collected from the study area and analyzed for total mercury concentrations and methyl mercury concentrations. The characteristics of vertical and horizontal distributions of total mercury and methyl mer-cury in the study area (farmland) are described in this paper. Much attention was paid to the transformation of inor-ganic Hg into organic mercury species in soils as well. The results showed that the farmland has been heavily con-taminated by Hg. Land cultivation activity,land utilization style and distance from the pollution source could be the dominant factors controlling the distribution of THg and MeHg. It is observed that active transformation of inorganic Hg into organic mercury species (MeHg) usually takes place in paddy soils.展开更多
基金Project supported by the Item of Shenyang Xi River Geochemistry Evaluation,China
文摘Heavy metal contamination of soils,derived from sewage irrigation,mining and inappropriate utilization of various agrochemicals and pesticides,and so on,has been of wide concern in the last several decades.The Shenyang Zhangshi Irrigation Area(SZIA) in China is a representative area of heavy metal contamination of soils resulting from sewage irrigation for about 30 years.This study investigated the spatial distribution and temporal variation of soil cadmium(Cd) and copper(Cu) contamination in the SZIA.The soil samples were collected from the SZIA in 1990 and 2004;Cd and Cu in soils was analyzed and then the spatial distribution and temporal variation of Cd and Cu in soils were modeled using Kriging methods.The results show that long-term sewage irrigation had caused serious Cd and Cu contamination in soils.The mean and the maximum of soil Cd are markedly higher than the levels in second grade standard soil(LSGSS) in China,and the maximum of soil Cu is close to the LSGSS in China in 2004 and is more than the LSGSS in China in 1990.The contamination magnitude of soil Cd and the soil extent of Cd contamination had evidently increased since sewage irrigation ceased in 1992.The contamination magnitude of soil Cu and the soil extent of Cu contamination had evidently increased in topsoil,but obviously decresed in subsoil.The soil contamination of Cd and Cu was mainly related to Cd and Cu reactivation of contaminated sediments in Shenyang Xi River and the import of Cd and Cu during irrigation.The eluviation of Cd and Cu in contaminated topsoil with rainfall and irrigation water was another factor of temporal-spatial variability of Cd and Cu contamination in soils.
文摘The modified three-step sequential extraction procedure proposed by the BCR was used to predict Pb and Cd fractional distribution in sewage sludge and tomato soil amended with sludge compost. There was no significant increasing of Pb and Cd contents in the soil with sludge application as compared with that in the reference soil. The Pb contents were much lower for the soil samples than for the National Soil Standards of Environmental Quality, but Cd contents in soil were much more than background mean Cd contents. Pb content in soil fractions was followed with residual Pb 〉 reducible Pb 〉 exchangeable and weak acid soluble Pb〉 oxidizable Pb. In all soil samples, the partitioning of Cd had the same extractability in the first two steps of the procedure and the residual fraction. Only a small fraction or almost zero extractability was observed at the oxidation step for Pb and Cd.
基金This study was funded by the Science and Technology Development Fund,Macao SAR,China(File 0159/2019/A3)the National Key Research and Development Program of China(2016YFD0800406).
文摘Determining the appropriate soil cadmium(Cd)criteria for vegetable production is important for ensuring that the Cd concentrations of the vegetables meet food safety standards.The soil extractable Cd criteria for vegetable production are also essential for both food safety and environmental management,especially in areas with a high natural background level.In the present study,soil total and extractable Cd criteria were derived using the approach of species sensitivity distribution integrated with soil aging and bioavailability as affected by soil properties.A dataset of 90 vegetable species planted in different soils was compiled by screening the published in literature in five bibliographic databases using designated search strings.The empirical soil-plant transfer model was applied to normalize the bioaccumulation data.After normalization,the intra-species variability was reduced by 18.3 to 84.4%.The soil Cd concentration that would protect 95%(HC_(5))of the species was estimated by species sensitivity distribution curves that were fitted by the Burr III function.The soil Cd criteria derived from the added approach for risk assessment were proposed as continuous criteria based on a combination of organic carbon and pH in the soil.Criteria for total Cd and EDTA-extractable Cd in the soil ranged from 0.23 to 0.61 mg kg^(-1)and from 0.09 to 0.25 mg kg^(-1),respectively.Field experimental data were used to validate the applicability and validity of these criteria.Most of the predicted HC5 values in the field experimental sites were below the 1:1 line.These results provide a scientific basis for soil Cd criteria for vegetable production that will ensure food safety.
基金financially supported by the National Natural Science Foundation of China (Grant Nos.20467001 and 40532014)
文摘This study assesses the level of contamination of Hg in farmland soils along the irrigating channel down-stream from Guizhou Organic Chemical Factory (GOCF),where metallic mercury is used as a catalyst to produce acetic acid. The total input of mercury into the environment,as announced by GOCF,is 140 t in the past 30 years (1971-2000). Sampling sites were chosen based on the distance from the source of pollution—the chemical factory. A total of 39 samples were collected from the study area and analyzed for total mercury concentrations and methyl mercury concentrations. The characteristics of vertical and horizontal distributions of total mercury and methyl mer-cury in the study area (farmland) are described in this paper. Much attention was paid to the transformation of inor-ganic Hg into organic mercury species in soils as well. The results showed that the farmland has been heavily con-taminated by Hg. Land cultivation activity,land utilization style and distance from the pollution source could be the dominant factors controlling the distribution of THg and MeHg. It is observed that active transformation of inorganic Hg into organic mercury species (MeHg) usually takes place in paddy soils.
