香港土壤中的重金屬含量及其污染現狀

通過詳細的土壤調查分析，探討了香港表層土壤(0～5cm)中重金屬的含量及其污染現狀。５８個代表性樣品的分析結果表明，香港土壤的As、Cd、Cu、Pb和Zn分別為13、1、17、57和55mg/kg；用NaHCO₃/DTPA浸提的有效態Cd、Cu、Pb和Zn分別為0.1、0.03、0.7和1.1mg/kg。 從土壤種類來看，除Pb元素之外，一般果園土壤的重金屬平均含量最高，菜園土壤次之，城市土壤和鄉村土壤更次之，林業土壤中的含量最低；但從Pb平均含量來看，果園和城市土壤較高，而在菜園土壤、鄉村土壤和林業土壤中的平均含量相差不大。從土地利用的分區來看，在商業區、工業區、農業區和林業區4種功能區中，通常是工業區的重金屬污染相對較嚴重，而林業區的土壤污染相對較輕。汽油燃燒和農業化學物質的投入，是香港土壤中Pb污染的重要來源。

Heavy metal contents in top soils in Hong Kong and their pollution levels were studied in the presented paper using soil survey. Averages of total As, Cd, Cu, Pb and Zn contents in the 58 selected soils were 13, 1, 17, 57 and 55 mg/kg soil, respectively. Average contents of NaHCO₃/DT-PA - extractable Cd, Cu, Pb and Zn in the soils were 0.1, 0. 03, 0. 7 and 1. 1 mg/kg soil, respectively. In general, the maximum average contents of heavy metal except for Pb were found in vegetable soil type, the medium ones were found in urban soil type and rural soil type, and the minimum ones were in forest soil type. However, the fruit soil type and urban soil type had the highest Pb contents. The average Pb contents in vegetable soil type, rural soil type and forest soil type were lower. Among the 4 function areas (i. e. agricultural, commercial, forest and industrial areas) in the city, more serious pollution by heavy metals were usually observed in industrial areas while minimum pollution was found in forest areas. Oil gas combustion was the major source of Pb pollution in the soils. Repeated applications of agrochemicals were an important input of As, Cu and Zn in the agricultural soils. Copyright © 1997 中國科學院地理科學與資源研究所; 中國地理學會.