Lead concentrations of soils in Beijing urban parks and their pollution assessment
北京城市公园土壤铅含量及其污染评价

Lead concentrations of surface soils taken from 30 typical parks in Beijing urban area were studied. The pollution index, which was used to assess the situation of soil pollution, was calculated according to the Soil Environment Quality Standard recommendedby European Union. The results indicated that the average concentration of Pb in soils was 66.2 mg/kg, ranging from 25 to 207 mg/kg;the pollution index was ranging from 0.51 to 4.15. It was found that soils from some parks were polluted with Pb apparently. The results of cluster analysis showed that all of theparks could be dividedinto three categories: (1) the parks with a history shorter than 100 years; (2) the parks with a history ranging between 200 and 400 years;and (3) the parks with a history longer than 400 years. Regression analysis was carried out to explore the relationship between two variables of Pb concentrations in soils and the history of parks. Using the "growth curve"to fit the datum, it could be concluded that the two variables were significantly positive correlated (p<0.001). Furthermore, geographical location of the parks was also an essential factor affecting the lead concentrations in the soils. In some parks with longer history and/or near the center of the city, the concentrations of Pb in the soilswere obviously high. However, Pb pollution was not notable in the soils of other parkswith relative short history.