水溶性磷酸盐对不同肥力石灰性土壤中铅的稳定研究

Immobilization of Lead with Soluble Phosphate in Calcareous Soils with Different Fertilities

在荒地土(S土)和农田土(F土)2个潮土土样中加入500mg.kg-1水溶性铅[Pb(NO3)2]后培养30d,之后按n(P)∶n(Pb)=6∶1加入Ca(H2PO4)2.H2O,培养105d后测定土壤性质。结果表明,土壤中仅加磷及加铅后再加磷时,F土Olsen-P质量分数均显著高于S土(P<0.05);土壤中仅加铅时,S土DTPA-Pb质量分数显著低于F土(P<0.05),但加铅后加磷,S土DTPA-Pb质量分数显著高于F土(P<0.05);土壤中仅加铅或仅加磷时,SrCl2-Ca均增加,而加铅土壤中加磷后,2种土壤SrCl2-Ca质量分数均低于仅加铅或仅加磷土壤。加铅和加磷均导致土壤pH降低,以加铅后加磷处理pH最低。对于F土,加铅和加磷均导致土壤电导率上升,对于S土,仅加铅和加铅后加磷导致土壤电导率上升,而仅加磷时,土壤电导率略有下降。可见,在未加入磷酸盐时,水溶性铅在贫瘠土壤中更易老化;磷酸盐对肥沃土壤中铅老化效果高于贫瘠土壤中的效果,磷酸盐对钙、铅的稳定分别有利于铅和钙有效性的降低。

In order to investigate the effect of soil fertility on the immobilization of Pb in soil with soluble phosphate,a sterile soil（S） and a fertile F soil（F） were spiked with 500 mg·kg-1 soluble Pb and incubated for 30 days,then amended with Ca（H2PO4）2·H2O at n（P）∶n（Pb）=6∶1,incubated for 105 days.Analysis of the samples indicated that,for soils amended only with phosphate or both with phosphate and Pb,Olsen-P concentrations of F soil were significantly higher than those of S soil（P〈0.05）.When the soil was only spiked with Pb,DTPA-Pb concentrations of S soil was significantly lower than that of F soil（P〈0.05）,however,after the Pb-spiked soil being amended with phosphate,that of S soil was significantly higher than that of F soil（P〈0.05）.When the soil was only spiked with Pb or phosphate,the SrCl2-Ca concentrations increased compared with the control,after the Pb-spiked soil amended with phosphate,the SrCl2-Ca concentrations of both soils were lower than those only spiked with Pb or phosphate.Lead and phosphate amendments resulted in lower soil pH,with those amended with both Pb and phosphate having the lowest values.Both Pb and phosphate amendments resulted in higher conductivity values for F soil;while for S soil,amendment with Pb only and with both Pb and phosphate resulted in higher conductivity,amendment with phosphate only resulted in lower conductivity compared with the control.The results suggest that,soluble Pb was better immobilized in soil with lower fertility when no phosphate is added,the immobilization of Pb with phosphate is more pronounced in soil with higher fertility,immobilization of Pb and Ca with phosphate helps reduce the availability of Ca and Pb,respectively.