Abstract
Cadmium in soils of coal-mining subsidence poses potential ecological risks. DTPA extraction and Tessier sequential extraction methods were used to investigate the speciation and bioavailability of Cd in subsidence soils of Guqiao Coal Mine. The results show that total Cd and availability Cd are highly correlated, and are both enriched in topsoil (0~20 cm). Cadmium in studied soils is 367 times of that in the Huainan background soil, with a high activation rate of 3786%. The proportions of different Cd species in studied soils are: residual fraction (5059%)>exchangeable fraction (2324%)> Fe-Mn oxides bound fraction (1577%)>carbonate bound fraction (618%)>organic bound fraction (422%). Bioavailable (exchangeable) and potentially bioavailable Cd (carbonate bound, Fe-Mn oxide bound, organic bound) account for 2324% and 2617%, respectively, which could be activated under the soil environment of mines. The organic matter, total nitrogen and total phosphor of soil are the main factors controlling Cd species. In addition, the variation of pH values in soil could promote the conversion of Cd in other forms to bioavailable forms.
Abstract
Cadmium in soils of coal-mining subsidence poses potential ecological risks. DTPA extraction and Tessier sequential extraction methods were used to investigate the speciation and bioavailability of Cd in subsidence soils of Guqiao Coal Mine. The results show that total Cd and availability Cd are highly correlated, and are both enriched in topsoil (0~20 cm). Cadmium in studied soils is 367 times of that in the Huainan background soil, with a high activation rate of 3786%. The proportions of different Cd species in studied soils are: residual fraction (5059%)>exchangeable fraction (2324%)> Fe-Mn oxides bound fraction (1577%)>carbonate bound fraction (618%)>organic bound fraction (422%). Bioavailable (exchangeable) and potentially bioavailable Cd (carbonate bound, Fe-Mn oxide bound, organic bound) account for 2324% and 2617%, respectively, which could be activated under the soil environment of mines. The organic matter, total nitrogen and total phosphor of soil are the main factors controlling Cd species. In addition, the variation of pH values in soil could promote the conversion of Cd in other forms to bioavailable forms.
Open Access
JUSTC
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