Soils from five vegetable gardens with different pH values werestudied. The study shows that the majority of the soil native Pb exists in theform of residual fraction and only a small amount in the form of exchangeablePb. But in the freshly retained Pb, residual fraction amounts to very little,and exchangeable Pb contents are different in different soils, with acidic soilranking first, then neutral soil and then alkaline soil. Soil with higher pHvalue retains and fixes more Pb than acidic soil, and their desorption order isjust opposite to that of retention. Increasing soil pH can promote Pb r...
