Linking atmospheric emission and deposition to accumulation of soil cadmium in the Middle-Lower Yangtze Plain, China

Cadmium (Cd) is one of the most toxic heavy metals in the environment. Atmospheric deposition has been found to be the main source of Cd pollution of soil on a large scale in China, and identification of the relationships between anthropogenic emission, atmospheric deposition, and Cd accumulation in soil is important for developing ways to mitigate Cd non-point pollution. In this study, the relationship between atmospheric emission, atmospheric deposition, and soil Cd accumulation in the Middle-Lower Yangtze Plain in China was investigated using datasets of atmospheric emission, deposition, and soil accumulation from the literatures published between 2000 and 2020. The results showed that the soil Cd accumulation rate in the study area exceeded the national average (4.0 mu g kg-1 yr-1) and continued to accumulate in recent decades, although the average accumulation rate decreased from 9.45 mu g kg-1 yr-1 (2000-2010 period) to 8.86 mu g kg-1 yr-1 (2010-2020 period). The contribution of atmospheric deposition flux to Cd increment in the soil was in the range of 22-29%, with the atmospheric deposition flux decreasing from 0.54 mg m-2 yr-1 (2000-2010) to 0.48 mg m-2 yr-1 (2010-2020), both values being greater than the national average. Atmospheric Cd deposition and emission were highly correlated in a provincial administrative region, which is close to a ratio of 1.0. Emission factors may be in a state of dynamic change due to the influences of new Cd emission control technologies and environmental policies. As the main sources of Cd emissions, dust, and smoke emissions per ton of non-ferrous metal production decreased by 64.7% between the 2000-2010 and 2010-2020 periods. Although new environmental policies have been instigated, atmospheric emission of Cd is still excessive. It was hoped that the findings of this work would provide a scientific basis for the rational control of atmospheric emissions and Cd pollution of soil.

Automated summary

This study investigated the relationship between atmospheric emission, deposition, and soil Cd accumulation in the Middle-Lower Yangtze Plain in China. The results showed that the soil Cd accumulation rate in the study area exceeded the national average and continued to accumulate in recent decades. The contribution of atmospheric deposition flux to Cd increment in the soil was in the range of 22-29%, with the atmospheric deposition flux decreasing over time.