砷污染耕地钝化剂的筛选与复配

Screening and Combining of Passivators for Arsenic Contaminated Arable Land

以砷污染耕地土壤为试验对象,对腐植酸钠、腐植酸、玉米生物炭、稻壳生物炭、膨润土、沸石、熟石灰这8种药剂进行钝化剂筛选试验。结果表明:8种药剂中,熟石灰、腐植酸和沸石对砷具有良好的钝化效果,作用于供试土壤后,土壤中有效砷含量分别下降了29.4%、17.3%和16.4%;熟石灰对砷的钝化机理主要包括沉淀作用以及对土壤中铁的活化作用,腐植酸对砷的钝化机理主要为吸附、离子交换及络合(螯合)作用,沸石对砷的钝化机理主要为吸附作用;在单一药剂筛选结果的基础上,获得腐植酸+熟石灰+FeSO4(复配1)和沸石+熟石灰+FeSO_(4)(复配2)2种复配剂,作用于供试土壤后,土壤中有效砷含量分别下降了39.3%和29.8%。复配剂在大幅度提升钝化效果的同时,有效避免了因单一药剂用量过大使土壤pH值升高产生的田间“烧苗”现象。

Taking arsenic contaminated arable soil as the test object,the passivator screening test was carried out on eight agents:sodium humate,humic acid,corn biochar,rice husk biochar,bentonite,zeolite and hydrated lime.The results showed that among the eight agents,hydrated lime,humic acid and zeolite had good passivation effects on arsenic;after acting on the tested soil,the content of available arsenic in the soil decreased by 29.4%,17.3%and 16.4%respectively.The passivation mechanism of hydrated lime to arsenic mainly includes precipitation and activation of iron in soil;the passivation mechanism of humic acid to arsenic is mainly adsorption,ion exchange and complexation(chelation);and the passivation mechanism of zeolite to arsenic is mainly adsorption.Based on the screening results of single agent,two kinds of compound agents:humic acid+hydrated lime+FeSO4(compound 1),zeolite+hydrated lime+FeSO_(4)(compound 2),were obtained;after acting on the tested soil,the content of available arsenic in the soil decreased by 39.3%and 29.8%,respectively.The application of compound agents not only greatly improved the passivation effect,but also effectively avoided the phenomenon of"burning seedlings"in the field caused by the increase of soil pH value due to the excessive dosage of a single agent.