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Title: Groundwater–surface water mixing shifts ecological assembly processes and stimulates organic carbon turnover

Environmental transition zones are associated with geochemical gradients that overcome energy limitations to microbial metabolism, resulting in biogeochemical hot spots and moments. Riverine systems where groundwater mixes with surface water (the hyporheic zone) are spatially complex and temporally dynamic, making development of predictive models challenging. Spatial and temporal variations in hyporheic zone microbial communities are a key, but understudied, component of riverine biogeochemical function. To investigate the coupling among groundwater-surface water mixing, microbial communities, and biogeochemistry we applied ecological theory, aqueous biogeochemistry, DNA sequencing, and ultra-high resolution organic carbon profiling to field samples collected across times and locations representing a broad range of mixing conditions. Mixing of groundwater and surface water resulted in a shift from transport-driven stochastic dynamics to a deterministic microbial structure associated with elevated biogeochemical rates. While the dynamics of the hyporheic make predictive modeling a challenge, we provide new knowledge that can improve the tractability of such models.
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  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  2. The Ohio State Univ., Columbus, OH (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 2041-1723; ncomms11237
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 7; Journal ID: ISSN 2041-1723
Nature Publishing Group
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
Sponsoring Org:
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES biogeochemical hotspot; deterministic selection; ecological drift; ecological null model; FTICR mass spectrometry; Hanford 300 Area; hyporheic zone; mixing model; organic carbon; phylogenetic beta-diversity; subsurface biogeochemistry; subsurface microbiology