选用重金属(Pb、Cd、Zn)和As复合污染土壤进行水稻盆栽试验,结果表明,碳酸钙的添加显著提高了土壤pH值,显著降低了土壤中交换态Pb、Cd、Zn和As的含量,与对照相比,交换态Pb、Cd、Zn和As含量分别最多降低了98.35％,93.72％,98.52％和69.48％.碳酸钙对水稻根、稻谷干重和总生物量没有显著影响,添加量过高时显著降低了水稻分蘖数和茎叶干重,说明过量施用碳酸钙对水稻生长会产生负面作用.因为碳酸钙的添加,水稻植株各部位重金属Zn含量显著降低,糙米中Zn含量最多减少了34.95％;根、谷壳中Pb、Cd含量显著降低,但糙米中含量却未显著降低;水稻各部位As含量均没有显著降低.参照《食品中污染物限量》(GB2762-2012),试验糙米中Pb、Cd、无机As含量均未达到限量标准.显然,碳酸钙的添加降低了Pb、Cd、Zn的生物有效性(水稻根系对Pb、Cd、Zn的吸收累积减少),但并未有效地抑制Pb、Cd向糙米转运;碳酸钙显著降低了土壤的交换态As含量,但并未使土壤中As的生物有效性明显降低(水稻植株各部位的As含量并未显著减少).

湘南烟区土壤pH值从80年代的偏酸性变为当前的偏碱性,短短20余年,pH值变化极为显著.在郴州市桂阳县偏碱烟田土壤中施用改良剂硫酸亚铁(FeSO4),研究其对偏碱土壤的调控效果以及对烟草吸收养分的影响,研究结果表明:(1)施用0.25 ～ 4.0 g kg-1的FeSO4能使土壤的pH值从7.87降低到7.58,但土壤pH值下降幅度不大.(2)施用0.25～ 4.0 g kg-1的FeSO4对土壤有机质、碱解N、速效K、交换性Ca、Mg、有效Mn、有效Cu、有效Zn含量没有显著影响,使土壤有效P含量降低了2.26％～ 17.70％,有效Fe含量增加了6.00％ ～ 26.73％.(3)施用FeSO4后烟叶中养分含量的变化基本与土壤中养分的变化规律一致,0.25～4.0 g kg-1的硫酸亚铁使烟叶Ca和P含量分别降低1.21％ ～ 11.36％ 、4.29％～11.66％,Fe、Mn和Zn含量分别提高了0.25％～8.15％、3.69％ ～ 7.72％和4.71％～8.63％.(4)FeSO4施用量为2.00 g kg-1为最佳施用量,当施用量较低时(＜2.0 g kg-1)能提高烟草的单叶重,达到了调控土壤pH值的目的,较高时(4.0 g kg-1)却降低了烟叶的株高和单叶重,抑制了烟草的生长.

通过水稻盆栽试验研究磷酸氢二钠(DSP)和羟基磷灰石(HAP)对污染土壤中重金属(Pb、Cd、Zn)向水稻迁移的影响.结果表明,①DSP和HAP都显著提高了土壤pH值和有效磷含量(p＜0.05),降低了土壤中Pb、Cd、Zn交换态含量,且HAP降低重金属交换态的效果较DSP好.水稻地上部分重金属含量与土壤中重金属交换态含量呈明显正相关关系,说明DSP和HAP通过降低土壤中重金属交换态含量从而达到减少重金属向水稻中迁移的目的.②DSP和HAP明显降低了水稻各器官Pb、Cd的含量,同时使水稻根、壳、糙米中Zn含量降低,但增加了茎叶中Zn的含量.与对照相比,DSP和HAP分别使糙米中Pb、Cd、Zn最大降低了48.72％、22.22％、25.35％和62.82％、66.67％、39.88％,但是糙米中Pb、Cd含量仍未达到食品卫生标准限值(GB2762-2012).③DSP和HAP处理都使水稻根干重逐渐减少,使茎叶、壳、糙米干重先增加后降低,在0.12g·kg-1时使水稻糙米产量最大.综上,DSP和HAP都能有效控制土壤中Pb、Cd、Zn向水稻中迁移,且HAP效果比DSP好,但磷添加量不宜过高.

通过水稻盆栽试验,研究了淹水灌溉(F)、灌浆期前湿润灌溉(A-F)、灌浆期后湿润灌溉(F-A)、淹水与湿润交替(AFA)这4种水分管理模式对水稻吸收土壤As的影响.结果表明,同F处理比较,A-F处理能显著降低水稻根和茎叶As含量,F-A和AFA处理都能显著降低水稻茎叶、谷壳、糙米As含量和糙米无机As含量.A-F、F-A、AFA处理对水稻生物量影响都不大,仅AFA处理减少了水稻根系生物量.F-A和AFA处理降低糙米As含量的机理是:灌浆期是水稻糙米吸收土壤As的关键时期,此时的湿润灌溉提高了土壤Eh,土壤溶液As(Ⅲ)与As(Ⅴ)浓度之和、As(Ⅲ)/As(Ⅴ)的比例都显著降低,从而使土壤As的迁移能力得到抑制.F-A处理降低水稻糙米总As和无机As含量的效果与AFA处理无显著差异,但F-A处理的操作更简单,因此,F-A处理应当是污染土壤中控制水稻糙米累积As的最佳水分管理模式.

Pot experiments were conducted to study the influence of two kinds of iron-containing materials(Fe(OH)3,FeCl3) on biological availability of arsenic and heavy metal in contaminated paddy soil.Results showed that the soil exchangeable arsenic content was not influenced by adding Fe(OH)3,while the addition of FeCl3 made soil exchangeable arsenic content decrease significantly,soil exchangeable arsenic content decrease 46% when adding 0.50 g/kg FeCl3.Furthermore,adding Fe(OH)3 made soil exchangeable lead and copper content decrease significantly,2.00 g/kg Fe(OH)3 led a decrease of 63% and 74% in exchangeable lead and copper,respectively.Contrary to Fe(OH)3,adding FeCl3 made soil exchangeable lead,cadmium and zinc content increase significantly,and soil exchangeable lead,cadmium and zinc increase 3 834%,247% and 1 744%,respectively,by adding 2.00 g/kg FeCl3.Results also showed that the addition of Fe(OH)3 had limit effect on brown rice inorganic arsenic,lead,cadmium,copper and zinc content.The influence of adding FeCl3 on brown rice inorganic arsenic,lead,cadmium,copper and zinc content was in different manners,adding 1.00 g/kg FeCl3 brown rice arsenic content decreased with the amount of 33%,while brown rice lead and copper content increased 147% and 50%,respectively.Results indicated that adding FeCl3 could effectively reduce the soil arsenic biological availability,however,promote the biological availability of soil heavy metal.Adding Fe(OH)3 couldn't make soil pH significantly influence,while FeCl3 made soil pH decrease significantly,which should be the important reason that FeCl3 could effectively fix soil arsenic,increase soil heavy metal exchangeable content.

Soybean is one of most important dicotyledonous food crops and is widely planted in Hunan Province, China. However, mining activity causes contamination of the soil in which soybean grows. To assess the impact of mining‐induced soil contamination on soybean plants, a geoaccumulation index ( I geo ) was used to evaluate 20 soil samples from the mining and smelting areas of southern Hunan Province. The results indicated that Zn ranged from uncontaminated to a moderately contaminated level ( I geo < 1), Pb was at a strongly contaminated level ( I geo > 3), and Cd was at an extremely contaminated level ( I geo > 5) across the whole study area. All of the studied soybean plants were affected by heavy metal Pb and Cd contamination, and the mean concentrations in seeds were 13.9 mg/kg and 2.95 mg/kg, respectively. The estimated bioconcentration factor and translocation factor showed that the soybean roots had a strong Cd bioconcentration capability and the stems had a strong translocation capability in terms of Pb, Cd, and Zn, with preferential transference of metals to the soybean leaves. The bioavailable fraction in the soil was characterized by the exchangeable fraction of heavy metals. In the present study, the bioavailable fractions of Pb, Cd, and Zn were significantly positively correlated with the concentration of these metals in soybean tissues (roots, stems, leaves, husks, and seeds). Environ Toxicol Chem 2013;32:2719–2727. © 2013 SETAC

In order to assess the effects of two chemical immobilization materials like diammonium phosphate and calcium carbonate on stabilization of heavy metal and arsenic compound contaminated sediment,the toxicity leaching test and the exchange fractionation of heavy metal and arsenic were studied.The results showed that the pH value of the sediment decreased with the treatment of diammonium phosphate,while the pH value of the sediment increased after adding calcium carbonate.The diammonium phosphate had significant effects on the stabilization of Pb,while made Zn and As greatly activated in sediment.The stabilizations of Pb,Cd and Zn were significant by adding calcium carbonate,while there was no obvious effects on As.Conclusively,calcium carbonate was more suitable for the compound pollution of heavy metal and arsenic in polluted sediment.