Wang Dan, Wei Wei, Liang Dong-Li, Wang Song-Shan, Hu Bin
College of Resources and Environment, North-West A&F University, Yangling 712100, China.
Huan Jing Ke Xue. 2011 Oct;32(10):3113-20.
Heavy metal fractions in soil play an important role in the bioavailability for plants. A pot experiment was carried out to study the transformation and bioavailability for pakchoi of exogenetic copper and hexavalent chromium in co-contaminated soil. The results showed that one month after tested heavy metals were added into soil, the chromium was present mainly in residual and organic bonded form while copper was mainly bound to hydrated oxides of iron and manganese as well as residual form. Lower concentrations copper (< or = 400 mg x kg(-1)) in soil could promote chromium transform from other forms to exchangeable form while higher concentrations copper (> or = 800 mg x kg(-1)) in soil would inhibit this transformation. Similarly, chromium in low concentrations (< or = 5 mg x kg(-1)) could facility copper transform to residual form while chromium in high concentrations (> or = 20 mg x kg(-1)) would reduce such transformation process. Both added chromium to soil polluted by high concentrations copper and added copper to high chromium content soil could promote the polluted soil reach quasi-equilibrium state. Additionally, adding copper in soil could inhibit chromium uptake of pakchoi by promoting soil OM-Cr transformed into RES-Cr. While adding chromium in soil could reduce copper uptake of pakchoi by stimulating the EXE-Cu transformed into the RES-Cu. Therefore, it is necessary to take into consideration the synthetic effects of copper and chromium when carrying on assessment and phytoremediation to co-contaminated soil.
土壤中的重金属组分对植物的生物有效性起着重要作用。进行了一项盆栽试验，以研究外源铜和六价铬在复合污染土壤中对小白菜的转化及生物有效性。结果表明，在向土壤中添加受试重金属一个月后，铬主要以残留态和有机结合态存在，而铜主要与铁、锰的水合氧化物以及残留态结合。土壤中较低浓度的铜（≤400 mg·kg⁻¹）可促进铬从其他形态转化为可交换态，而较高浓度的铜（≥800 mg·kg⁻¹）则会抑制这种转化。同样，低浓度的铬（≤5 mg·kg⁻¹）可促进铜转化为残留态，而高浓度的铬（≥20 mg·kg⁻¹）则会降低这种转化过程。向高浓度铜污染的土壤中添加铬以及向高铬含量的土壤中添加铜均可促进污染土壤达到准平衡状态。此外，在土壤中添加铜可通过促进土壤有机态铬转化为残留态铬来抑制小白菜对铬的吸收。而在土壤中添加铬可通过刺激可交换态铜转化为残留态铜来降低小白菜对铜的吸收。因此，在对复合污染土壤进行评估和植物修复时，有必要考虑铜和铬的综合效应。
