The impact of industrialization on the distribution of heavy metals in surrounding soil: Evidence from the Chang-Zhu-Tan urban agglomeration, central China

Rapid industrial development has resulted in serious pollutants to the urban transitional areas. But less is known on the spatial distribution and ecological risk of heavy metals (HMs) caused by regional industrialization. In present study, soils, bedrocks and plant tissues were collected in the industrial transitional areas of Chang-Zhu-Tan Urban Agglomeration (CUA) of China. Results indicated that HMs contamination in the CUA was closely connected to the distribution of regional industries, and the pollution of HMs mainly focused on the exceed of cadmium (Cd: 48.2 %), mercury (Hg: 10.8 %) and lead (Pb: 11.5 %), which presented a diffusion trend towards the surrounding environment with the industrial center as the starting point. Additionally, the structural equation model (SEM) demonstrated that the other pollutants accompanied by metals discharge might further exacerbate the ecological risk of HMs. In the detected soil properties, Soil total organic carbon (TOC) content was the key factor affecting the Hg and Pb migration, while the distribution of Cd was more affected by the soil pH. Despite HMs contamination in the intersection area of CUA was relatively light. Taking the industrial distribution in the CUA into consideration, residents in the industrial central areas of Xiangtan (XT) and Zhuzhou (ZZ) cities might have a significant higher risk of HMs exposure. Fortunately, the application of organic fertilizers may have an effective limiting effect on the current Cd migration in the CUA region.