| The mining of non-ferrous metals mines in Hunan province make many areas affected by the harm of heavy metals and As pollution. Some industrial and mining areas in Zhuzhou,Chenzhou and Hengyang has different levels of heavy metals and As compound pollution. Heavy mentals and As contaminated soil make rice products quality decline easily. Rice polluted by heavy metals and As are harm to human body health. As and Fe in the soil is easy to form sediment which is difficult to soluble, exogenous iron-containing materials play a positive role in controlling As contaminated soil, So exogenous iron-containing materials are used to fixe As in the contaminated siol. The research which is about to translocation patterns of heavy mentals and As in paddy-soil system by adding exogenous iron rarely reported yet. The pot experiments was conducted, through the contrast experiment, to study the influence of two kinds of iron-containing materials (Fe(OH)3,FeCl3) on heavy metals and As contents in the soil, discuss the translocation characteristics and translocation mechanism of As and heavy metals in paddy as well. The purpose is to provide some scientific basis and technical support for forming a kind of effective technology repairing As contaminated soil. The main conclusions of the experiments are follows:(1) The soil exchangeable heavy metals and As contents are decreased by adding Fe(OH)3. The addition of FeCl3make soil exchangeable As contents decreased while make certain soil exchangeable heavy metals contents significantly decreased. Soil exchangeable Pb, Cd and Zn increase3834%,247%and1744%, respectively, by adding2.00g/kg FeCl3.(2) Both of the two kinds of meterials can control the arsenic contents in paddy. The effect of controlling by FeCl3is more obvious compared with Fe(OH)3; FeCl3Contents of As in root, stem,shell and brown rice decrease23.5%～58.4%,25.5%～35.6%,29.3%～56.0%and33.3%～47.2%, compared with control experiment respectively,by adding1.00-2.00g/kg FeCl3.(3) Accumulation of As,Pb,Cd(expet adding Fe(OH)3),Cu and Zn in root is decreased by adding Fe(OH)3and FeCl3; Accumulation of As, Pb, Cd and Cu in stem is decreased generally by adding Fe(OH)3while Zn in stem is increased; Accumulation of As and Pb in shell is decreased slightly by adding Fe(OH)3; Accumulation of As and Cu in brown rice is increased generally by adding Fe(OH)3,while Pb, Cd, and Zn in brown rice is decreased. Accumulation of As and Cd in stem is decreased generally by adding FeCl3, while Pb, Cu and Zn in stem is increased generally. Accumulation of As in shell is decreased generally by adding FeCl3,while Pb, Cd, Cu and Zn in shell is increased generally; Accumulation of As in brown rice is decreased generally by adding FeCl3,while Pb, Cd, Cu and Zn in brown rice is increased generally.(4) Fe(OH)3increased translocation of Pb from root to stem, decreased translocation of Pb from root to shell slightly, reduced translocation of Cd from root to stem and brown rice, increased translocation of Cd from root to shell slightly, trend to increase translocation of Cu from root to stem,shell and brown rice, increased translocation of Zn from root to stem,shell and brown rice;Coefficient of Zn in stem,shell and brown rice increase138.4%,89.7%and82.6%by adding2.00g/kg Fe(OH)3; Coefficient of As from root to stem,shell and brown rice increase slightly.FeCl3increased translocation of Pb from root to stem shell and brown rice, increased translocation of Cd from root to shell and brown rice, increased translocation of Zn from root to stem,shell and brown rice; Coefficient of Pb,Cu and Zn in stem increase335.7%,129.4%and62.2%by adding2.00g/kg FeCl3, Coefficient of Pb and Cd in shell increase367%and372%by adding2.00g/kg FeCl3, Coefficient of Pb in brown rice increase100.0%by adding1.00g/kg FeCl3, Coefficient of Cd in brown rice increase158.3%～226.2%by adding0.125～2.00g/kg FeCl3, Coefficient of As from root to stem increase slightly.(5) Soil pH value are significant decreased by adding FeCl3, Correlation analysis showed the relationship between soil exchangeable Pb, Cd, Zn, Pb in stem and soil pH are highly significant negative correlation,relationship between Cu in shell and soil pH were significant negative correlation; Relationship between Pb, As in root and soil pH were highly significant negative correlation, relationship between As in shell,brown rice and soil pH were significant negative correlation.(6) The soil-paddy system experiment results showed that the effect mechanism of iron-containing materials on the migration of arsenic and heavy metals from soil to the paddy come from two aspects. The first is changing the soil pH value, making As and heavy metals in soil adsorped and desorped the second may be associated with increasing paddy yield and amounts of iron plaque, thereby contributing to the paddy uptake of Cd, Zn and other heavy metals. |
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