A model combined with the atmospheric deposition flux to predict the accumulation of cadmium in rice (Oryza sativa L.) grain

Hunan Province, a major rice-producing region in China, faces severe cadmium (Cd) contamination in rice grains. Cd, a heavy toxic metal, accumulates in rice through the soil–rice system, posing health risks via the food chain. Effective management relies on identifying pollution sources to guide targeted control and reduction strategies. Through the data collected over the past 5 years across four different regions, a multiple linear regression model was established to explore the effects of those factors influencing Cd accumulation in rice tissues, including the input fluxes of soil Cd, atmospheric deposition Cd (DICd), irrigation water Cd (IRCd), and fertilizer Cd (CFCd). Atmospheric deposition was identified as a major source of Cd input, with a higher annual average input flux than irrigation water and fertilizers. In the industrial and mining zone Zhuzhou, atmospheric deposition accounted for 96.42% of the total Cd input. In the regions with an increasing level of atmospheric deposition, Cd exhibited higher soil Cd concentrations but lower pH. Total soil Cd (TCd) concentrations demonstrated a significant positive correlation with both soil available Cd (ACd) concentrations and DICd. Additionally, TCd and DICd were determined to be the critical factors affecting the accumulation of Cd in rice tissues. As indicated by the results, the spatial variation in rice Cd accumulation resulted from various sources of Cd input, highlighting the necessity to closely monitor Cd input fluxes across various regions. This study provides a benchmark for understanding the impact of atmospheric deposition on Cd accumulation in rice grains.