不同养分对磷酸盐固定的污染土壤中铜锌生物有效性的影响

Changes in Bio-availability of Immobilized Cu and Zn Bound to Phosphate in Contaminated Soils with Different Nutrient Addition

采用盆栽试验,在磷酸盐固定铜、锌单一及复合的三级污染(Cu200mg·kg-1、Zn400mg·kg-1)红壤和水稻土中,种植黑麦草40d,测定不加养分、加入KCl和NH4Cl、K2SO4和(NH4)2SO4后土壤中有效态铜锌含量、黑麦草生物量及其铜锌吸收量,以讨论养分对污染土壤中磷酸盐固定态铜锌的活化作用.结果表明,磷酸盐固定的铜单一、锌单一和铜锌复合污染红壤中,增加养分,有效态铜锌的含量都较未加入养分的增高,并且养分KCl和NH4Cl的增高幅度大于K2SO4和(NH4)2SO4,其中在磷酸盐固定的锌单一污染红壤中,有效态锌含量较未加入养分时增幅高达133.4%.虽然加入K2SO4和(NH4)2SO4,促进了红壤中黑麦草植株的生长,最大增幅达22.2%,但同时也增加了植株21.5%～112.6%的铜锌吸收量.调节养分对水稻土中铜锌的生物有效性没有显著影响.施入氮钾等养分能够改变磷酸盐固定的污染红壤中铜锌的生物有效性,对固定的铜锌都有活化作用.因此,在重金属污染土壤的修复中要充分考虑施肥等养分条件对固定钝化的重金属活性的影响.

Bio-availability of Cu and Zn fixed by phosphate in contaminated soils with application of nutrients were measured by pot experiment. It was simulated for the third national standardization of copper and zinc polluted soils by adding copper and zinc nitrate into red and paddy soils, respectively and together. Phosphate amendment was added to the soils to fix Cu and Zn, then added KCl and NH4Cl or K2SO4 and （NH4）2SO4 fertilizers following to plant Ryegrass, which was harvested after 40 d. Available Cu/Zn content in soils and biomass, Cu/Zn content in the shoot of Ryegrass were determined. Results showed that, compared with no nutrient application, adding KCl and NH4Cl/K2SO4 and （NH4）2SO4 to polluted red and paddy soils increased the available Cu and Zn content in red soil significantly. The increasing order was KCl and NH4Cl 〉 K2SO4 and （NH4）2SO4. Especially in single Zn polluted red soil, the available Zn content increased by 133.4% in maximum. Although adding K2SO4 and （NH4）2SO4 could promote the growth of Ryegrass on red soil, and the largest increasing was up to 22.2%, it increased Cu and Zn content in the shoot of Ryegrass for 21.5%-112.6% remarkably. These nutrient effects on available Cu and Zn were not significantly in paddy soil. It was suggested that application of nitrogen and potassium fertilizers to soils could change the bio- availability of Cu/Zn. So it is necessary to take full account of the nutrient influence to the heavy metal stability which fixed by phosphate in contaminated soils when consider contaminated soils remediation by fertilization.