酸化和有机质积累对茶园土壤铅生物有效性的影响

本文用土培试验研究了质地差异较大的二种茶园土壤酸化和有机质积累引起的水溶性铅、有效态铅和铅的化学形态的变化。结果表明,土壤酸化可显著地促进其它形态的铅向可交换态铅转化,增加土壤铅的水溶性和生物有效性。当土壤pH较高(pH>4)时,增加土壤有机质可促进土壤铅的活化,但在pH较低(pH<4)的土壤中,有机质积累降低了土壤中的有效态铅。酸化和有机质积累对铅的生物有效性影响在砂质土壤比粘质土壤更为明显。

Effects of Acidification and Organic Matter Accumulation on Lead Bio-availability in Tea Garden Soils

The increased accumulation of lead (Pb) in tea is widely concerned.The study on the factors influencing Pb concentration in tea is necessary for the production of high quality tea.In this study,soils of two tea gardens (Yellowish red soil and Red soil) were collected and incubated by adding acid and organic manure for studying the effects of acidification and organic matter accumulation on Pb bio-availability of tea garden soils.Water-soluble Pb,NH4OAc extractable Pb and chemical forms of Pb in the incubated soils were characterized.The results showed that soil acidification promoted transformation of other forms of Pb into exchangeable Pb,and thus increased water solubility and bio-availability of Pb in the soils.Accumulation of organic matter could activate Pb in soils with pH>4,whereas accumulation of organic matter decreased Pb bio-availability in lower pH soils (pH<4).The effects of pH and organic matter on Pb bio-availability were more significant in sandy soil than that in clayey soil.