The environment of Beijing as the capital city of China is highly affected by industrial pollution. The area of the Capital Iron & Steel Factory of Beijing is a typical example for industrially contaminated sites in the Beijing area. In the present study, we collected topsoil and section samples from the Capital Iron & Steel Factory site and its surrounding area in high resolution, which were analyzed on organic carbon concentrations and carbon isotopic compositions. The results reveal both anthropogenic and natural contributions of carbon to these soils. Three profiles from the vicinity and two profiles from the area surrounding the steel (company) display vertical patterns in soil organic carbon concentrations and isotopic compositions that resemble more commonly observed downward gradients in soil carbon chemistry and indicate microbial carbon turnover.

delta C-13(soc) values in the transverse distribution change towards either more C-13 or C-12 depleted values with distance to the center of the steel factory area. The study discloses that coal and/or coal combustion products represent the dominant source of soil organic carbon in the industrial region, and the affection decreases with increasing distance to the center of the industrial area. Organic matter of the soil from the surrounding area of the industrial site is mainly derived from coal or coal combustion prdducts as well as C3 arid C4 plants.

An assessment of the transverse and vertical distribution of the concentration and isotopic compositions of bulk organic carbon in topsoil and soil profiles from industrial sites and the surrounding area combined With three-dimensional spatial distribution and variation analysis were applied to identify the degree, sources, and processes of industrial pollution. (C) 2016 Elsevier B.V. All rights reserved.