There are tremendous amount of unknown chemicals in the environment, which are commonly called untargeted chemicals. They plays a significant role in river ecosystem metabolism and nutrients cycling, with further impacts on water quality and food security. However, the assemblages of tens of thousands of unknown and continuously changing organic molecules in an ecosystem make it challenging to characterize the composition and determine the drivers of variation. The dynamic nature of untargeted chemicals records the information of upstream land-use sources and in-stream hydrobiogeochemical processes on watersheds. By screening a single water sample from the outflow of a watershed, it is theoretically possible to simultaneously predict water sources and quantify all ecosystem processes occurring upstream in a watershed simply by testing for the presence of the diagnostic metabolomic signatures (fingerprints). Our aim is to build upon these strategies to identify the different metabolomic signatures that are indicative of different land-use sources and watershed processes. In this study, we predict the land-use and microbial communities using untargeted chemicals from 4 watersheds in northwestern Oregon. We are trying to understand if land-use sources or microbial communities are driving the composition of untargeted chemicals. The results indicate a strong seasonal variability in both chemical composition and microbial communities driven by seasonal environmental changes. We also find that microbial communities and environmental changes can be better predicted by untargeted chemical composition, than land-use. This suggest the co-existing and inter-linked roles of chemicals and microbes in future climate changes. Future studies will focus on understanding the mechanism of correlation between chemical composition and microbial communities, and identifying indicator species of microbes and chemicals in each seasonal and watershed group.
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 untargeted_chemical_composition_in_river_waters_are_driven_by_changes_of_land-use_or_microbial_communities_.pdf | 2.23 MB |