A research team led by LUO Yongming from the Institute of Soil Science of the Chinese Academy of Sciences (ISSCAS), along with their collaborators, made advancements in understanding arsenic contamination in China’s surface soils. The study was published in Nature Sustainability. 

Using a machine-learning model developed from 3,542 regional surveys encompassing over one million soil samples, the team produced annual maps showing a consistent rise in arsenic levels in China's surface soils from 2000 to 2040.  

The model uncovered an increase from an average arsenic concentration of 11.9 mg/kg in 2000 to 12.6 mg/kg in 2020, projecting a further increase to 13.6 mg/kg by 2040. It identified primary anthropogenic sources such as non-ferrous metal mining (68.0%), fossil energy consumption (15.8%), non-ferrous metal smelting (13.2%), and agricultural activities (3.0%) as key contributors to this rise. 

Moreover, the team showed how agricultural practices, particularly the use of arsenic-laden fertilizers and pesticides, raise the overall arsenic levels, and reduce the area of land with arsenic concentrations exceeding 20 mg/kg due to crop absorption, akin to phytoremediation. However, it warned that arsenic absorbed by crops can enter the food chain, posing potential health risks. 

Further research discovered that 13.3% of the rice grown in fields with soil arsenic levels between 20 and 30 mg/kg exceeded safety limits, with about one-third of arsenic-exceeding rice in China coming from these fields. This points to the urgent need for reassessment of current standards and increased focus on affected areas to ensure food safety. 

This study provides a macroscopic method for quantifying the environmental impact of human activities, with potential applications not only in China but globally across various research fields.