洛阳城区及郊区土壤中Pb的分布特征及化学形态研究

The Distribution and Chemical Speciation of Lead in Urban and Suburb Soil of Luoyang City

对洛阳城市不同功能区表土中的Pb含量与化学形态以及工业和交通对土壤Pb污染的影响进行了研究,结果表明洛阳城市表土中Pb的含量分别为工业区(126.94mg kg-1)>城市道路(77.44mg kg-1)>居民区(59.76mg kg-1)>郊区农用地(52.39mg kg-1)>公园(41.43mg kg-1)>高校校园(36.49 mg kg-1)。工业区周围的土壤Pb含量随与工业区距离的增加而下降,应用地积累指数评价,洛阳城市土壤Pb污染处于轻度到中度污染之间,其中工业区和城区道路地积累指数较高,这些区域的土壤已受到Pb的较强污染。公路和铁路沿线两侧土壤中Pb含量分布也随距离的增加而下降,交通沿线两侧最大的Pb浓度在主导风向一侧10米附近。城市土壤Pb的化学形态以残余态和铁锰氧化物结合态为主,各形态比例为残余志>铁锰氧化物结合态>碳酸盐结合态>有机结合态。

This study reports the distribution and chemical speciation of lead in urban topsoils from different land - use classes in Luoyang City, China. The mean concentrations of Pb in the soils are 126.94 mg kg^-1 for industrial area, 77.44 mg kg^-1 for roadsides, 59.76 mg kg^-1 for residential area, 52.39 for suburb area, 41.43 mg kg^-1 for parks and 36.49 mg kg^-1 for university campus, respectively. The concentrations of Pb in the soils around industrial area decreased with the increasing distance to industrial area. The highest concentration of Pb in road and railway side soil occurred in the distance of 10 meters. Based on geoaccumulation index （ Igeo ）, most of the urban topsoils in Luoyang City were polluted by Pb. Chemical fraction distribution of Pb in Luoyang urban soils was dominated by the residual fraction and Fe - Mn oxide fractions. The percentage of Pb in five fractions increased in the order： residual 〉 Fe - Mn oxide 〉 organic 〉 carbonate 〉 exchangeable forms. The soils from industrial, roadside and residential areas had higher content of Pb bound to carbonate, suggesting that Pb of these soils were more mobile and bioavailabile.