溶解性有机物对土壤中铜生物有效性的影响

Influence of Dissolved Organic Matter(DOM)on Bioavailability of Copper in Soils

采用盆栽试验,研究了模拟铜污染土壤中溶解性有机物（DOM）对红壤、褐土和黑土3种不同类型土壤中小油菜（Brassia campestris）的生长及对Cu生物有效性的影响。结果表明,随着DOM的加入,黑土和红壤中小油菜的出苗率均有所下降,尤其是当DOM添加量大于100mgC·kg^-1时,红壤中小油菜出苗率显著降低（P〈0.05）,而对褐土的出苗率影响不大;供试3种土壤中小油菜生物量均呈先上升后下降的趋势,其在DOM添加量为50mgC·kg^-1时生物量达到最大,但比较而言,3种土壤中小油菜生物量由大至小的顺序为：黑土〉褐土〉红壤;随着土壤中添加DOM浓度的升高,小油菜植株体内铜浓度大致呈现不断增加的趋势,且3种土壤中植株体内的铜浓度均在DOM添加量为200mgC·kg^-1时达最高值,与对照处理及添加量为50mgC·kg^-1处理间差异显著（P〈0.05）;土壤中有效态Cu含量则随DOM量的增加呈不断升高趋势,3种供试土壤有效态Cu含量以红壤最高,当DOM添加量为0-100mgC·kg^-1时,褐土中有效态铜含量高于黑土;而当DOM添加量为150-200mgC·kg^-1时,黑土中的有效态铜含量却高于褐土。这表明随着外源性DOM进入土壤,可导致土壤中Cu的生物有效性不断发生变化,从而直接影响作物的生长以及作物对Cu的吸收。

The pot experiments were conducted to study the influence of the dissolved organic matter（DOM） extracted from chicken manure on the growth of cole（Brassia campestris ） and Copper（Cu） bioavailability in red soils, brown soils and black soils contaminated by copper. The results indicated that the rates of emergence of cole both in black soils and red soils decreased with the addition of DOM, while the rate of emergence of cole in red soils decreased significantly （P〈0.05）, especially when the amount of DOM addition was more than 100 mgC·kg^-1. The rate of emergence of cole in Brown soils was not significantly affected by the addition of DOM. The biomass of cole increased and then decreased with the increased amount of addition DOM in three soil types, while it reached at the peak when the DOM concentration was by 50 mgC·kg^-1. In comparison with different soils, the biomass of cole ranked from high to low in turn black soil, brown soil and red soil. With the increased DOM concentration in all three soil types, both the copper concentration in cole and the available copper content in soils were gradually increased, while it reached at the peak when DOM content was 200 mgC·kg^-1. Compared to three soil types, the available Cu content in red soils was significantly higher than that in black soils and brown soils＇with the increased added amount of DOM in soils, which might be closely related to the lower pH in red soils. Therefore, the Cu bioavailability in soils increased with the added DOM entering into soils, which indirectly affected the growth of crops and the Cu absorption by crops.