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Stabilizing effects on a Cd polluted coastal wetland soil using calcium polysulphide
Citation:
Tu, C., F. Guan, Y. Sun, P. Guo, Y. Liu, L. Li, K. Scheckel, AND Y. Luo. Stabilizing effects on a Cd polluted coastal wetland soil using calcium polysulphide. Geoderma. Elsevier BV, AMSTERDAM, Netherlands, 332:190-197, (2018). https://doi.org/10.1016/j.geoderma.2018.07.013
Impact/Purpose:
In recent years, with the rapid development of industrialization, agricultural intensification and urbanization in the coastal zones, a large quantity of industrial wastes, agricultural fertilizers and pesticides, mining wastewaters, and municipal sewage have been emitted to the coastal wetland soils. Contaminants, such as heavy metals, could transfer from these potential waste streams into the coastal wetland soils causing pollution, and resulting human health and ecological risks to the coastal wetland soil ecosystem. The average Cd concentration in estuarine and coastal environments in China varies from 0 to 9.7 mg kg-1. However, in some particular sites adjacent to mining and smelling districts in the coastal zone of China, Cd concentrations can be as high as 200-400 mg kg-1. Therefore, it is of great urgency to develop green and sustainable remediation technologies for cost-effective remediation of heavy metal polluted coastal wetland soils. The aim of the present study was therefore to investigate the stabilization effects of CaSx on the remediation of Cd-contaminated wetland soil, and to clarify the dosage-dependent effects of CaSx application on soil enzyme activities and soil microbial metabolic and community diversity. The results of this study will be helpful to the development of an efficient, safe and long-acting stabilization soil amendment for the in situ remediation of Cd-contaminated wetland soil.
Description:
In this study, different dosages of calcium polysulphide (CaSx) were used as an amendment to investigate effects on the immobilizing of Cd in a wetland soil by pot experiment. In addition to chemical analysis (pH and bioavailable Cd concentration), changes in soil enzyme activities, microbial carbon utilization capacity, metabolic and community diversity were examined to assess dynamic impacts on soil environmental quality and toxicity of Cd resulting from ameliorant dosing. Soil pH increased immediately upon CaSx amendment compared to the unamended control (CK), and then declined slowly to a level lower than CK. Diethylenetriamine pentaacetic acid (DTPA) extractable Cd concentration was determined to characterize the bioavailability of Cd in the soil. The CaSx dose-dependent effect observed that with increasing CaSx dosage, the immobilizing efficiency decreased. Soil urease and catalase activity assays and Biolog EcoPlate assay indicated that early stage addition of CaSx significantly inhibited soil microbial activities. However, mid and late stage time periods showed the inhibition effects were alleviated, and the microbial activities could be recovered in 1% and 2% CaSx treatments. Moreover, with increasing incubation time, microbial community diversity and richness were significantly recovered in 1% and 2% CaSx treatments compared to the CK. No considerable changes were observed in the 5% CaSx treatment. Conclusively, the 1% CaSx amendment was an efficient and safe dosage for the stabilization of Cd contaminated wetland soil. This study contributes to the development of in situ remediation ameliorants and technologies for heavy metal polluted wetland soils.
URLs/Downloads:
DOI: Stabilizing effects on a Cd polluted coastal wetland soil using calcium polysulphide
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