Wang, Z. ; Jimenez-Fernandez, O.* ; Osenbrück, K.* ; Schwientek, M.* ; Schloter, M. ; Fleckenstein, J.H.* ; Lueders, T.*
Streambed microbial communities in the transition zone between groundwater and a first-order stream as impacted by bidirectional water exchange.
Water Res. 217:118334 (2022)
The input of nitrate and other agricultural pollutants in higher-order streams largely derives from first-order streams. The streambed as the transition zone between groundwater and stream water has a decisive impact on the attenuation of such pollutants. This reactivity is not yet well understood for lower-order agricultural streams, which are often anthropogenically altered and lack the streambed complexity allowing for extensive hyporheic exchange. Reactive hot spots in such streambeds have been hypothesized as a function of hydrology, which controls the local gaining (groundwater exfiltration) or losing (infiltration) of stream water. However, streambed microbial communities and activities associated with such reactive zones remain mostly uncharted. In this study, sediments of a first-order agriculturally impacted stream in southern Germany were investigated. Along with a hydraulic dissection of distinct gaining and losing reaches of the stream, community composition and the abundance of bacterial communities in the streambed were investigated using PacBio long-read sequencing of bacterial 16S rRNA gene amplicons, and qPCR of bacterial 16S rRNA and denitrification genes (nirK and nirS). We show that bidirectional water exchange between groundwater and the stream represents an important control for sediment microbiota, especially for nitrate-reducing populations. Typical heterotrophic denitrifiers were most abundant in a midstream net losing section, while up- and downstream net gaining sections were associated with an enrichment of sulfur-oxidizing potential nitrate reducers affiliated with Sulfuricurvum and Thiobacillus spp. Dispersal-based community assembly was found to dominate such spots of groundwater exfiltration. Our results indicate a coupling of N- and S-cycling processes in the streambed of an agricultural first-order stream, and a prominent control of microbiology by hydrology and hydrochemistry in situ. Such detailed local heterogeneities in exchange fluxes and streambed microbiomes have not been reported to date, but seem relevant for understanding the reactivity of lower-order streams.
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Publication type
Article: Journal article
Document type
Scientific Article
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Keywords
Groundwater-surface Water Exchange ; Losing And Gaining Stream ; Lower-order Streams ; Nitrate Reduction ; Streambed Microbiomes
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Language
english
Publication Year
2022
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0
HGF-reported in Year
2022
ISSN (print) / ISBN
0043-1354
e-ISSN
1879-2448
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Volume: 217,
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Article Number: 118334
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Elsevier
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Amsterdam [u.a.] ; Jena [u.a.]
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Reviewing status
Peer reviewed
POF-Topic(s)
20403 - Sustainable Water Management
30202 - Environmental Health
Research field(s)
Environmental Sciences
PSP Element(s)
G-504300-005
G-504700-001
Grants
Deutsche Forschungsgemeinschaft
Gabriele Barthel
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Erfassungsdatum
2022-05-03