Abstract: Three soil profiles and twenty-three surface soil samples, developed from various parent materials, were collected from different tea gardens near highway in Zhejiang province. The total, five chemical fractions (exchangeable, carbonate bound, organic matter-bound, oxides bound and residual forms) and water-solubility of Pb and Cd in the soils were characterized. The results showed that concentrations of total and different chemical fractions of Pb and Cd in the soils varied with locations and soil properties. Increased Pb and Cd concentrations in surface layer of the soil profiles suggested that Pb and Cd accumulation in the soils was related to soil pollution and fertilizer application. The concentrations of organic matter-bound, oxides bound and residual forms of Pb and Cd were mainly controlled by total Pb and Cd in the soils. However, exchangeable and water-soluble Pb and Cd, which had high potential risk, increased with decreasing pH. The results indicate that long-term plantation of tea could cause sol acidification and elevated concentrations of bio-available heavy metals in the soil, and hence aggravated the risk of heavy metals.

Key words: Soil in tea garden, Acidification, Pb, Cd, Chemical fractions