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Wheat straw biochar reduces environmental cadmium bioavailability
Citation:
Cuj, L., M. Noerpel, K. Scheckel, AND J. Ippolito. Wheat straw biochar reduces environmental cadmium bioavailability. ENVIRONMENT INTERNATIONAL. Elsevier B.V., Amsterdam, Netherlands, 126:69-75, (2019). https://doi.org/10.1016/j.envint.2019.02.022
Impact/Purpose:
Soil heavy metal pollution is a serious problem globally, leading to food chain accumulation and ultimately human health risk. In China specifically, soil heavy metal pollution can be linked to recent rapid industrialization, urbanization, and subsequently widespread solid, liquid, and gaseous metal emissions. A “cancer villages” map published online identified 247 locations in China with major health issues likely associated with man-induced pollution (China.org.cn, 2013). In China and other locations where soil heavy metal pollution is an issue, it is generally considered that human exposure to Cd is most often through the consumption of contaminated food. Biochar (BC), a carbon enriched material, is produced via pyrolysis of biomass at moderate temperature (~500°C) under limited oxygen concentrations. Because of its unique physical-chemical characteristics, BC is recognized as a multifunctional material for treating heavy metals polluted soils and water. We hypothesized that maximum biochar heavy metal sorption likely requires more than 24 hours to attain equilibrium, potentially on the order of days or weeks. Furthermore, we hypothesized that, given time, biochar-heavy metal interactions may lead from sorption via surface functional groups to precipitation of heavy metal mineral phases. Our objectives were to 1) utilize biochar to reduce bioavailable soil Cd and solution Cd, 2) investigate biochar-metal sorption and 3) identify form(s) present as affected by biochar application rate and time using both a sequential extraction procedure and X-ray absorption spectroscopy.
Description:
Cadmium contamination in waters and soils can lead to food chain accumulation and ultimately deterioration in human health; means for reducing bioavailable Cd are desperately required, and biochars may play a role. Long-term (240 d) lab incubation experiments were utilized to explain wheat straw-derived biochar effects on Cd sorption and decreasing Cd bioavailability in soils and solutions (0, 5, and 15% biochar as wt:wt or wt:vol, respectively), and to identify Cd forms present using both the European Community Bureau of Reference (BCR) chemical sequential extraction procedure and synchrotron-based X-ray absorption spectroscopy (XAS). Biochar Cd removal was up to ~90% from Cd-containing solutions and contaminated soil as compared to the control. Based on the wet chemical sequential extraction procedure in conjunction with XAS, biochar application promoted the formation of (oxy)hydroxide, carbonate, and organically bound Cd phases. As a material, biochar may be promoted as a tool for reducing and removing bioavailable Cd from contaminated waters and soils. Thus, biochar may play a role in reducing Cd bioaccumulation, trophic transfer, and improving environmental quality and human health.
URLs/Downloads:
DOI: Wheat straw biochar reduces environmental cadmium bioavailability
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