Environmental geochemical mapping and multivariate geostatistical analysis of heavy metals in topsoils of a closed steel smelter: Capital Iron & Steel Factory, Beijing, China

• High-density geochemical mapping of heavy metals in soils was performed.
• The study area is centered on a former steel smelter.
• Multivariate statistical analysis was used to process data.
• The sources of heavy metals in the soils were determined or discriminated.
• Steel-smelting activities led to Cu, Pb, Cd and Zn contaminants in the soils.

A high-density survey was conducted in this study to determine the spatial distribution and possible sources of heavy metals at the former Capital Iron & Steel Factory, Beijing, China. A total of 400 surface soil samples were collected at a density of 16 samples per km2, and the concentrations of heavy metals, such as Ni, Cr, V, As, Cu, Pb, Cd, Zn and Hg, were analyzed. The spatial distribution characteristics of these metals were demonstrated by environmental geochemical mapping. The mean concentrations of Ni, Cr, V and As are close to the background values. Enrichment factors show that the soil concentrations of Cu, Pb, Cd, Zn and Hg were higher than the background values, especially Hg. Multivariate geostatistical analysis suggests that Cu, Pb, Cd and Zn have similar properties and their presence was mainly from steel-smelting activities. However, the Hg contamination was more weakly related to the steel smelting activities, partially due to other anthropogenic activities, such as the combustion of coal for heating.