Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China; Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, Hangzhou, 310058, China.
Key Laboratory of Recycling and Eco-treatment of Waste Biomass of Zhejiang Province, School of Environmental and Natural Resources, Zhejiang University of Science & Technology, Hangzhou, 310023, China.
Environ Pollut. 2020 Nov;266(Pt 1):115194. doi: 10.1016/j.envpol.2020.115194. Epub 2020 Jul 15.
The contamination of arsenic (As) and cadmium (Cd) in paddy soils is widely reported and these two metals are difficult to be co-remediated due to the contrasting chemical behaviors. This poses a challenge to simultaneously decrease their availability in soil and accumulation in rice via immobilization by amendments, especially in in-situ fields. This study compared the effects of carbide slag, lodestone and biochar on the bioavailability of As and Cd in soil and their accumulation in rice tissues and root Fe-Mn plaque at tillering and mature stages in a paddy field. The addition of three amendments significantly limited the mobilization of As and Cd in soil and decreased their accumulations in brown rice by 30-52% and 9-21%, respectively. Carbide slag was most whereas lodestone least effective in As and Cd immobilization in the tested contaminated soils. Community Bureau of Reference (BCR) sequential extraction analysis showed that the amendments changed the forms of As and Cd to less-available. Activated functional groups of the amendments (e.g. -OH, C-O, OC-O, OH and CO) sequestered metals by precipitation, adsorption, ion exchange or electrostatic attributes contributed greatly to the As and Cd immobilization in soil. Furthermore, the amendments promoted the formation of Fe-Mn plaque in rice roots, which further limited the mobility of As and Cd in soil and prevented their transport from soil to rice roots. The application of carbide slag and biochar but not lodestone increased rice yield compared to the unamended control, indicating their applicability in situ remediation. Our study gives a strong reference to select immobilizing amendments for food safe production in co-contaminated paddy soils.
稻田土壤中砷（As）和镉（Cd）的污染广泛存在，由于化学行为相反，这两种金属很难同时进行共修复。这给通过改良剂固定化来降低土壤中它们的有效性和减少其在水稻中的积累带来了挑战，尤其是在原位农田中。本研究比较了电石渣、磁铁矿和生物炭对稻田土壤中 As 和 Cd 生物有效性及其在水稻组织和根铁锰斑块中积累的影响，在分蘗期和成熟期。三种改良剂的添加显著限制了土壤中 As 和 Cd 的迁移，并分别使糙米中 As 和 Cd 的积累减少了 30-52%和 9-21%。在受污染土壤中，电石渣对 As 和 Cd 的固定效果最为显著，而磁铁矿的固定效果最差。基于社区标准参考（BCR）的连续提取分析表明，改良剂改变了 As 和 Cd 的形态，使其变得更不易被利用。改良剂的活化功能基团（如-OH、C-O、OC-O、OH 和 CO）通过沉淀、吸附、离子交换或静电属性来螯合金属，这对土壤中 As 和 Cd 的固定化起到了重要作用。此外，改良剂促进了水稻根系中铁锰斑块的形成，这进一步限制了土壤中 As 和 Cd 的迁移，并防止了它们从土壤向水稻根系的传输。与未改良对照相比，电石渣和生物炭的应用增加了水稻产量，而磁铁矿的应用则没有，这表明它们在原位修复中的适用性。我们的研究为选择固定化改良剂以确保在受污染的稻田土壤中生产安全食品提供了有力参考。
