A new early warning for paddy soil ecological security: Low molecular weight DOM enhances the spread of arsenic-ARGs across the paddy soil-air interface

Paddy soil ecological security is the basis for maintaining rice health. Paddy soils with long-term manure application contain high levels of both heavy metals (arsenic) and antibiotic resistance genes (ARGs), which pose an overlapping threat to paddy soil ecological security. In this process, it is still unknown how the dissolved organic matter (DOM) affects the fate of arsenic-ARGs across the paddy soil-air interface. Here we found that small molecular weight DOM (LDOM) more strongly drove the fate of arsenic-ARGs across the paddy soil-air interface, being 1.35 and 1.43 times higher than that of large molecular weight DOM. LDOM contributed more biologically active substances (aliphatic compounds) to stimulate microbial carbon metabolism cycling across the paddy soil-air interface, in which Bacillus was the key species. Potential synergistic detoxification of the ABC transporter role was discovered, which is valuable for identifying ecological security threats to rice.