Lead Accumulation in Soils under Different Land Use Types in Beijing City
ZHENG Yuanming, CHEN Tongbin, CHEN Huang, ZHENG Guodi, LUO Jinfa(Center for Environmental Remediation, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing100101, China)
To obtain an overview of land use effects on the accumulation of Pb in the soil,600 samples were collected from Beijing. The results showed that the geometric mean of allsoil samples was 26.6 mg/kg, significantly higher than the background concentration ofBeijing soil (24.6 mg/kg). Based on the assessment compared with background concentration,increasing of Pb was found to be the highest in greenbelt and orchard and to a somewhatlesser extent in vegetable field and paddy field, whereas anthropogenic input seemed to be lessimportant in natural soil. And the concentrations of Pb in greenbelt and orchard weresignificantly higher than those in other land use types. Using baseline as the criterion, theorchard showed the highest ratio beyond the limit for 21.4% . Corresponding values ofgreenbelt, vegetable field, paddy field, and cornfield were 18.2%, 11.1%, 8.3% and 5.2%,respectively and 7.2% for the total samples. The samples over the limit were mainlydistributed in districts of Changping, Chaoyang, Daxing, Fengtai, Haidian and Shijingshan.The six districts were attributed with high ratios beyond the baseline limit for soil samples.Therefore, the concentrations of Pb in the soils declined gradually with the increment of thedistance of the soils from the city zone. Through present investigation, it was found that theimpacts of human activities of atmospheric precipitation, landfill of waste and fertilizerapplication are probably the important reasons for Pb concentrations under different land-usetypes.