Heavy Metal Contamination Characteristics in Acid Soil-rice Systems and the Corresponding Human Health Risk in a Mining and Smelting Area in Jiangxi Province.

To understand the effects of mining activities on soil cadmium and rice, a typical mining area was selected. The Cd content in a considerable number of soils exceeded the standard limitation GB/T 36,783 - 2018, with a rate of 42.03%. Further analysis revealed soil total Cd content was strongly correlated with soil bioavailability of Cd (R2 0.721**), pH (R2 0.386**) and soil total content of lead(R2 0.678**). It suggests that soil total Cd content and soil pH significantly affect rice Cd levels, and that acid soil increases soil Cd bioavailability [Soil Cd (B)] and accumulation in rice grain. Furthermore, a mathematical dynamic fitting is developed to describe the relationship between rice Cd content, soil pH, and soil Cd bioavailability in acidic soil (pH 5-5.5). Rice Cd content (mg/kg) = - 179.2 + 67.24 × (Soil pH) - 12.81× [Soil Cd (B)] - 6.28 × 153(Soil pH) 2 + 65.79 × [Soil Cd (B)]2. This study identifies the main types of pollutants emitted by industrial activities and recommends Cd as the most concerning pollutant for rice planting and paddy soil.