Spatial Distribution Change of Topsoil Pb between 2004 and 2013 in Shijiazhuang City, China

PurposeTo understand the spatial distribution change of topsoil Pb in Shijiazhuang urban and suburb between 2004 and 2013.

MethodSoil samples were systematic collected at high density from the surface layer (0-20 cm) in Shijiazhuang urban and surrounding counties. The basic parameter data of Pb were compared between 2004 and 2013. Using spatial analysis module of ArcGIS 9.3, the spatial distribution of annual Pb-content were compared, and the Pb pollution status was evaluated by the ground accumulation index method during 2004—2013.

Results(1) The Pb average content changed slightly from 2004 to 2013. The average Pb-content of 2004 and 2013 was 23.04 and 24.31 mg/kg, respectively. However, the maximum value and coefficient of variation changed greatly, the maximum value increased from 59.50 mg/kg to 82.50 mg/kg, and the coefficient of variation increased from 20.23 % to 23.45 %. (2) From 2004 to 2013, the low Pb-content soil area decreased, meanwhile the high-content area increased. The areas of very low value and low value decreased from 545.10 km² to 388.08 km², and the areas of high value and very high value increased from 545.10 km² to 594.00 km². (3) In study area, Pb pollution was relatively light, but the pollution situation was gradually developing. In 2004, the pollution zone was mainly in urban area, and pollution level was slight. In 2013, a small amount of moderate pollution appeared in Zhengding New District, and the light pollution expanded in suburban counties.

ConclusionThe distribution of Pb was closely related to the main economic construction activities in the area. The changes of Pb-content distribution reflect the economic and social changes in Shijiazhuang City during 2004-2013.