CM-200819-4097863 A horizontal permeable reactive barrier stimulates nitrate removal and shifts microbial ecology during rapid infiltration for managed recharge

WATER RESEARCH

卷:144

Article

Beganskas, Sarah¹  Gorski, Galen¹  Weathers, Tess¹  Fisher, Andrew T.¹  Schmidt, Calla³  Saltikov, Chad²  Redford, Kaitlyn²  Stoneburner, Brendon²  Harmon, Ryan^1,4  Weir, Walker^1,5 

[1] Univ Calif Santa Cruz, Earth & Planetary Sci, Santa Cruz, CA 95064 USA

[2] Univ Calif Santa Cruz, Microbiol & Environm Toxicol, Santa Cruz, CA 95064 USA

[3] Univ San Francisco, Environm Sci, San Francisco, CA 94117 USA

[4] Colorado Sch Mines, Hydrol Sci & Engn, Golden, CO 80401 USA

[5] Univ Nevada Reno, Hydrol Sci, Reno, NV 89557 USA

关键词: Denitrification;    Managed aquifer recharge;    Permeable reactive barrier;    Nitrate reduction;    Infiltration;    Soil microbiology;   

DOI  :  10.1016/j.watres.2018.07.039

来源: Elsevier

【 摘 要 】

We present results from field experiments linking hydrology, geochemistry, and microbiology during infiltration at a field site that is used for managed aquifer recharge (MAR). These experiments measured how a horizontal permeable reactive barrier (PRB) made of woodchips impacted subsurface nitrate removal and microbial ecology. Concentrations of dissolved organic carbon consistently increased in infiltrating water below the PRB, but not in un-amended native soil. The average nitrate removal rate in soils below the PRB was 1.5 g/m(2)/day NO3-N, despite rapid infiltration (up to 1.9 m/d) and a short fluid residence time within the woodchips (<= 6 h). In contrast, 0.09 g/m(2)/day NO3-N was removed on average in native soil. Residual nitrate in infiltrating water below the PRB was enriched in delta N-15 and delta O-18, with low and variable isotopic enrichment factors that are consistent with denitrification during rapid infiltration. Many putative denitrifying bacteria were significantly enhanced in the soil below a PRB; Methylotenera mobilis and genera Microbacterium, Polaromonas, and Novosphingobium had log(2) fold-changes of +4.9, +5.6, +7.2, and +11.8, respectively. These bacteria were present before infiltration and were not enhanced in native soil. It appears that the woodchip PRB contributed to favorable conditions in the underlying soil for enhanced nitrate removal, quantitatively shifting soil microbial ecology. These results suggest that using a horizontal PRB could improve water quality during rapid infiltration for MAR. (C) 2018 Elsevier Ltd. All rights reserved.

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