Survey on the regional contamination of heavy metal and study on the spatial distribution of soil are the basis for decision-making in environmental management and pollution control. Thus, since 1990s, Professor CHEN Tongbin and his research team of Institute of Geographic Sciences and Natural Resources Research, Chinese Academic Sciences, have been engaged in the investigation and health risk assessment of soil heavy metal contamination.

Using traditional grid sampling method, accurate distribution information of pollutants could only be obtained with high density sampling due to the higher spatial heterogeneity of heavy metals in soil. In order to solve this problem, regional stratified sampling scheme was introduced to increase the representativeness of soil sampling. Compared to regular grid sampling, the stratified sampling lowered the quantity of samples by 60% at the same accuracy, which significantly reduced the workload and cost of soil pollution survey.

Focusing on the accurate mean concentration of soil heavy metals, traditional interpolation methods all have a smoothing effect with underestimating the maxima while overestimating the minima. The researchers evaluated the precision and uncertainty of different interpolation methods. Based on this evaluation results, a probability prediction method was proposed to increase the accuracy of soil contamination mapping and contaminated area estimation.

According to more than 1000 soil samples, the research team mapped the soil heavy metals distribution (more than 40 pieces of maps) and developed the safe culture division of main crops of Beijing city. A management information system, based on geographic information systems, has been established to assess the risk of agricultural soils heavy metal pollution.

These methods have been applied in provinces of Hunan, Guangxi, Yunnan and Gansu in China, providing technical support for the national survey on soil environmental qualities. About 50 related papers have been published and the study results have been awarded the Beijing Science and Technology Progress Award.