Heavy Metal Contamination of Urban Soil in an Old Industrial City (Shenyang) in Northeast China

Urban soil is an important indicator of human exposure to heavy metals in the urban terrestrial environment. Many studies have indicated that urban soils are contaminated by heavy metals and this phenomenon has been attributed mainly to modern industries, traffic and mining activities in urban areas.

Shenyang, the largest industrial city in Northeast China, is historically known as an industrial base and well-constructed city, with heavy machinery and manufacturing as the major industries. With rapid economic development, environmental quality has severely deteriorated. Heavy metal pollution is one of the most serious problems in this city.

To assess the concentration and distribution patterns of heavy metals in urban soil, and identify the relationship between urban land use and the heavy metal contamination of urban soil, LI Xiaoyu et al. conducted experiment in the Tiexi Industrial District, located in the western part of Shenyang.

Ninety-three soil samples were collected from the top 15 cm of the soil layer and were analyzed for heavy metal concentrations of Pb, Cu, Cr, Zn, Mn, Cd, As and Hg. The data revealed a remarkable variation in heavy metal concentration among the sampled soils. The mean values of all the heavy metal concentrations were higher than the background values.

In the estimated maps of heavy metals, several hotspots of high metal concentrations were identified. Pb and Cu showed a very similar spatial pattern, indicating that they were likely from the same source. There is a clear heavy polluted hotspot of Pb, Cu, Zn, Cd and As in the northeast part of the Tiexi Industrial District. There were also hotspots for other heavy metals in other areas. This is mainly the result of the industrial processing that occurred in the study area.

All of these data confirmed that Pb, Cu, Zn, Cd and As were a result of anthropogenic activities, especially from industrial processes. For Cr and Mn, the concentration patterns showed low spatial heterogeneity, with low correlation to other metals, indicating that the concentration of Cr and Mn were mainly caused by natural factors such as soil parent materials. The result was published in Geoderma in 2013, 192: 50-58.