Hu Bin, Liang Dong-li, Zhao Wen-long, Miao Shu-yin
Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, College of Resources and Environment, Northwest Agriculture and Forestry University, Yangling 712100, China.
Huan Jing Ke Xue. 2012 Aug;33(8):2817-24.
Pot experiments and laboratory analysis methods were used to investigate the form transformation of additional copper and selenium and their bioavailability for pakchoi (Brassica chinensis) in co-contaminated soil. The results showed that Cu mainly existed in residual bound form, while selenium was present mainly in organic bound and residual form in the uncontaminated soil. In the contaminated soil, copper was mainly bounded to hydrated oxides of iron and manganese, while Se was in exchangeable and carbonate forms. After one month of growing season, Cu tended to transfer into organic bound fractions, while Se tended to bind to hydrated oxides of iron and manganese. The I(R) value of Cu decreased with increasing copper and selenium concentrations, while the I(R) value of Se decreased with increasing Se concentration and had nothing to do with the concentration of exogenous Cu for both before planting and after harvesting of pakchoi. The parameters estimated by S curve fitting indicated that suitable amount of Se (< or = 10 mg x kg(-1)) could promote the Cu uptake by pakchoi, and certain amount of Cu (< or = 400 mg x kg(-1)) could promote Se absorption by pakchoi. Both the I(R), values for Cu and Se had similar trends as the Cu, Se concentrations in pakchoi, which meant that the I(R) value could be used to evaluate the bioavailability of heavy metals in soil. Partial correlation analysis showed that Cu and Se in exchangeable and organic bound forms in soil had better bioavailability for pakchoi. Therefore, the I(R) value of elements in soils and the change of elements before planting and after harvesting of pakchoi can be used as indicators for evaluating the bioavailability of heavy metals.
采用盆栽试验和实验室分析方法，研究了复合污染土壤中添加铜和硒的形态转化及其对小白菜（Brassica chinensis）的生物有效性。结果表明，在未污染土壤中，铜主要以残留态存在，而硒主要以有机结合态和残留态存在。在污染土壤中，铜主要与铁、锰的水合氧化物结合，而硒以交换态和碳酸盐态存在。经过一个月的生长季，铜倾向于向有机结合态转化，而硒倾向于与铁、锰的水合氧化物结合。随着铜、硒浓度的增加，铜的I(R)值降低，而硒的I(R)值随硒浓度的增加而降低，且在小白菜种植前和收获后，其I(R)值均与外源铜浓度无关。通过S曲线拟合估算的参数表明，适量的硒（≤10 mg·kg-1）可促进小白菜对铜的吸收，一定量的铜（≤400 mg·kg-1）可促进小白菜对硒的吸收。铜、硒的I(R)值与小白菜中铜、硒浓度的变化趋势相似，这意味着I(R)值可用于评价土壤中重金属的生物有效性。偏相关分析表明，土壤中交换态和有机结合态的铜、硒对小白菜具有较好的生物有效性。因此，土壤中元素的I(R)值以及小白菜种植前和收获后元素的变化可作为评价重金属生物有效性的指标。
