有机物料对滨海盐渍土重金属根际效应的影响 Ⅰ.土壤内源Zn形态分布

研究了排水条件下施用腐熟有机物料、种稻改良滨海盐渍土内源Zn形态分布。结果表明,单淹水使土中各形态Zn一定程度上向生物有效性较低的Zn形态转化,有效态Zn降低。土壤盐分量不同,明显影响无定形氧化铁结合态、紧结有机态以及硅酸盐矿物态Zn变化。种稻不施有机物料,根际交换态和硅酸盐矿物态Zn亏缺;碳酸盐结合态、氧化锰结合态和无定形氧化铁结合态Zn富集。根际Zn形态转化强度大于非根际,其有效态Zn量接近临界值并高于非根际。有机物料利于根际内外土壤中硅酸盐矿物态Zn的转化,低盐土壤根际更强烈。随有机物料用量增加,促使根际硅酸盐矿物态、碳酸盐结合态及氧化锰结合态Zn向交换态、紧结有机态和无定形氧化铁结合态Zn转化,低盐土壤较明显。

Rhizospheric effect of organic material on heavy metals in coastal saline soil I Distribution of soil native zinc forms

This paper studied the distribution of native zinc forms in coastal saline paddy soils with different salt contents under drainage condition and after applying decomposed organic material. The results showed that waterlogging was beneficial to the transformation of soil native zinc forms to those less available to plant in some degrees, suggesting the reduction of soil available zinc. Different salt contents significantly affected the variations of Zn bound to amorphous iron oxide (AFeO-Zn), Zn bound to tight humus (TOM-Zn) and silicate mineral Zn (MIN-Zn). Planting rice without the application of organic material was conducive to the depletion of exchangeable Zn (EX-Zn) and MIN Zn and the enrichment of Zn bound to carbonate (CAB-Zn), Zn bound to manganese oxide (MnO-Zn) and AFeO-Zn in rhizospheric soil, and the stronger zinc transformations in contrast to non rhizospheric soil. This induced that in rhizospheric soil, available zinc was close to its critical value which was higher than that in non rhizospheric soil. Organic material improved the transformation of MIN-Zn in rice rhizospheric and non rhizospheric soils, especially in rhizospheric soil with low salt content. With the increase of organic material incorporated with the soils, the transformation of MIN-Zn, MnO-Zn and CAB-Zn to EX-Zn, TOM-Zn and AFeO-Zn was promoted in rice rhizospheric soils with different salt contents, particularly with low salt content.