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 NaHCO 3/DTPA——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.
Scopus Subject Areas
- Geography, Planning and Development
- Earth and Planetary Sciences(all)
- Environmental quality
- Heavy metals
- Hong Kong