铁改性木本泥炭对镉砷复合污染稻田的修复效果研究

Study on the simultaneous remediation of Cd and As contamination in the paddy soil by applying iron modified woody peat

铁改性木本泥炭是一种新型环保有机类土壤调理剂,在稻田镉砷复合污染治理方面具有很大的应用潜力。为研究铁改性木本泥炭对稻田镉砷同步钝化效果的稳定性,在珠三角地区开展了三年的田间定位试验。结果表明:施加铁改性木本泥炭可显著降低稻米镉砷含量,下降率分别达到了41.3%~57.6%和40.1%~55.8%;可显著促进水稻增产,水稻单季撒施2250 kg/hm^(2)铁改性木本泥炭,水稻增产810~1125 kg/hm^(2),增产率为14.3%~18.4%;土壤的有效态镉和有效态砷含量同步降低,下降率分别为25.8%~46.4%和42.6%~56.1%。而单施木本泥炭仅对稻米镉的吸收积累表现出较好的抑制作用,单施铁粉仅抑制了稻米砷的积累。此外,施加铁改性木本泥炭后,土壤pH提高了0.33~0.44个单位,有机质增加了2.1~3.3 g/kg,阳离子交换能力(CEC)提高了1.0~2.6 cmol/kg。这表明铁改性木本泥炭可以有效改善土壤的理化性质。对比2016—2018三年(六季)铁改性木本泥炭修复稻田镉砷复合污染效果发现,3年间早稻稻米镉砷含量下降率、产量增幅的年际差异均较小,晚稻亦然,表明铁改性木本泥炭可以稳定地抑制稻米镉砷积累、提高稻米产量。

As a new type of environmentally and friendly organic soil conditioner,iron-modified woody peat(IMP)has good application potential in the restoration of cadmium-arsenic compound contaminated farmland.In this study,the efficiency and long-term application stability of IMP were investigated in field trails with early and late season rice in the Pearl River Delta region from 2016 to 2018.The results showed that IMP can make the rice yield increase and the Cd and As concentrations of grain decrease significantly by application 2250 kg/hm^(2).Compared with the control group,the yield of rice increased by 810~1125 kg/hm^(2),and the average annual rate of growth arranged from 14.3%to 18.4%.Moreover,after the application of IMP,the contents of Cd and As in grain were significantly reduced by 41.3%~57.6%and 40.1%~55.8%respectively.The analysis of soil available Cd and As contents showed that IMP can simultaneously reduce the content of available Cd and As in the paddy soil by 25.8%~46.4%and 42.6%~56.1%,respectively.Additionally,the soil pH increased by 0.33~0.44,organic matter by 2.1~3.3 g/kg,and the cations exchange capacity(CEC)by 1.0~2.6 cmol/kg,which indicating that iron-modified woody peat can also effectively improve the physical and chemical properties of the soil.Compared with the control group,the application of iron powder or woody peat separately had limited effect on the immobilization of Cd and As(<for the early and late rice,respectively),while the IMP showed synergetic effect on the immobilization of Cd and As.Besides,there were no significantly differences of the rice yields,the Cd and As concentrations within three early reason rice,and it was similar to the late rice,which indicated that:IMP had the stable effect on the increasing of the rice yield and controlling the mobility and bioavailability of the Cd and As in the paddy soil.