Environmental and microbial factors shape dissolved organic matter across multiple ecosystems
Bixi Guo, Yongqin Liu, Jianjun Wang, Qiang Zheng, Quan Shi, Chen He, Nianzhi Jiao
Abstract
Dissolved organic matter, one of the largest carbon pools in aquatic ecosystems, plays a critical role in global carbon cycling, yet how its composition shifts across Earth’s main ecosystems remains unclear. Here, we tracked its changes along the aquatic continuum across four ecosystems using ultrahigh-resolution mass spectrometry and found a trend toward increasing homogenization and recalcitrance. The molecules present in all ecosystems increased from 65 ± 20% in glaciers to 97 ± 0.7% in the open ocean, primarily shaped by terrestrial inputs. In contrast, the others declined from 82 ± 31 % to 3 ± 0.7%, driven by microbial communities, especially in the glaciers and open ocean. Therefore, physicochemical processes lead to the homogenization of dissolved organic matter composition along aquatic continuums, while biological transformations increase its uniqueness. This study unveils key mechanisms driving dissolved organic matter turnover across ecosystems and underscores its pivotal role in carbon cycling under climate change. Dissolved organic matter composition is homogenised across multiple aquatic ecosystems, with terrestrial inputs and microbial communities controlling universal and non-universal fractions respectively, according to analyses of dissolved organic matter samples from China.