Yafeng Han, Chenchen Qu, Xiping Hu, Peng Wang, Dan Wan, Peng Cai, Xingmin Rong, Wenli Chen, Qiaoyun Huang*, Warming and humidification mediated changes of DOM composition in an Alfisol, Science of The Total Environment, 2021, 150198. https://doi.org/10.1016/j.scitotenv.2021.150198.
- •Warming enhanced accumulation of microbial–derived aliphatic DOM and colloidal Ca.
- •Fungi dominated the consumption of plant-derived aromatic DOM under warming.
- •Humidification facilitated release of plant–derived DOM along with Fe dissolution.
- •Moisture impacted on DOM more severely than temperature under their interactions.
Dissolved organic matter (DOM) represents the most mobile and reactive pool of soil organic matter (SOM). Climate changes, such as global warming and altered precipitation exert considerable influences on the quality and quantity of soil DOM. However, rare reports have focused on the interactive effects of soil warming and increased precipitation. In the present study, we conducted a 90–day incubation experiment to investigate how the concentration, source and chemical composition of DOM from an Alfisol respond to the variations of temperatures (15, 30 and 45 °C) and moistures (40%, 60%, and 80% of saturated soil water content). Four DOM components were identified through fluorescence excitation emission matrix (EEM)–parallel factor analysis (PARAFAC). Increased temperature alone aggravated the decomposition of plant–derived aromatic components (C2 and C4) but promoted the accumulation of microbial–derived aliphatic carbon (C1) and tryptophan–like component (C3). Increased fungi/bacteria ratio with warming was responsible for the decomposition of plant–derived components. Warming–induced disassociation of Ca–bearing mineral to colloidal Ca facilitated the accrual of microbial–derived aliphatic DOM. Humidification alone and humidification + warming significantly increased the concentration of DOM and the percentage of plant–derived aromatic carbon (C2, C4), which was attributed to the release of Fe–bearing mineral–OC. Accompanying above findings with the results of two–way ANOVA and Variation partition analysis, we found that humidification, rather than warming, may modify considerably the quantity and chemodiversity of DOM in Alfisols under climate changes which in turn impact global C cycling and the ultimate climate.