中文摘要：

采用土培盆栽试验和室内分析相结合的方法,研究了Cu、Se复合污染土壤中2种金属的形态转化及其对生物有效性的影响.结果表明,在未污染土壤中,Cu主要以残渣态存在,Se主要以有机结合态和残渣态存在.在外源Cu、Se污染土壤中,平衡后（14 d）,外源Cu主要以铁锰氧化物结合态存在,Se主要以可交换态及碳酸盐结合态存在;小白菜收获后,土壤中的Cu向有机结合态转化,而Se向铁锰氧化物结合态转化.外源Cu与土壤结合程度（IR值）均随外源Cu和Se浓度升高而逐渐降低;而Se与土壤结合程度（IR值）与外源Cu浓度无关,随外源Se浓度升高而下降.S型曲线拟合方程表明,适量的Se（≤10mg.kg-1）可以促进小白菜对Cu的吸收,同样适量的Cu（≤400 mg.kg-1）能促进小白菜对Se的吸收.土壤的Cu、Se的IR值与小白菜体内Cu、Se含量呈显著负相关（P〈0.05）,小白菜种植前后土壤中可交换态和有机结合态铜和硒的变化量与小白菜地上、地下含量也呈显著相关（P〈0.05）.因此,土壤元素的IR值和作物种植前后该元素形态的变化量均可作为评价重金属生物有效性的指标.

英文摘要：

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 IR value of Cu decreased with increasing copper and selenium concentrations,while the IR 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（≤10 mg·kg-1） could promote the Cu uptake by pakchoi,and certain amount of Cu（≤400 mg·kg-1） could promote Se absorption by pakchoi.Both the IR values for Cu and Se had similar trends as the Cu,Se concentrations in pakchoi,which meant that the IR 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 IR 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.