This study investigated the spatial distribution and environmental functions of dissolved organic matter (DOM) in 89 grassland soils across China. Humic-like and high molecular weight DOM fractions were found to be more abundant in northern China, correlating with lower soil respiration and net ecosystem productivity. Conversely, lower molecular weight and proteinaceous fractions were more prevalent in southern China and showed a potential link to nasopharyngeal cancer incidence. The study highlights the importance of understanding the diverse functions of soil DOM and the need for locally tailored strategies to mitigate its impacts.
