Helmholtz Zentrum München, Institute of Groundwater Ecology, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany.
Helmholtz Zentrum München, Institute of Groundwater Ecology, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany.
Water Res. 2021 Feb 1;189:116631. doi: 10.1016/j.watres.2020.116631. Epub 2020 Nov 10.
Riverbank filtration has gained increasing importance for balancing rising groundwater demands and securing drinking water supplies. While microbial communities are the pillar of vital ecosystem functions in groundwater, the impact of riverbank filtration on these communities has been understudied so far. Here, we followed changes in microbial community composition based on 16S rRNA gene amplicon sequence variants (ASVs) in an initially pristine shallow porous aquifer in response to surface water intrusion during the early stages of induced riverbank filtration over a course of seven weeks. We further analyzed sediment cores for imprints of river-derived ASVs after seven weeks of riverbank filtration. The onset of the surface water intrusion caused loss of taxa and significant changes in community composition, revealing low disturbance resistance of the initial aquifer microbial communities. SourceTracker analysis revealed that proportions of river-derived ASVs in the groundwater were generally <25%, but locally could reach up to 62% during a period of intense precipitation. However, variation partitioning showed that the impact of dispersal of river-derived ASVs on changes in aquifer microbial community composition was overall outweighed by species sorting due to changes in environmental conditions caused by the infiltrating river water. Proportions of river-derived ASVs on aquifer sediments were <0.5%, showing that taxa transported from the river into the aquifer over the course of the study mainly resided as planktonic microorganisms in the groundwater. Our study demonstrates that groundwater microbial communities react sensitively to changes in environmental conditions caused by surface water intrusion, whereas mass effects resulting from the influx of river-derived taxa play a comparatively minor role.
河岸过滤在平衡不断增长的地下水需求和保障饮用水供应方面变得越来越重要。尽管微生物群落是地下水重要生态系统功能的支柱，但到目前为止，河岸过滤对这些群落的影响还没有得到充分研究。在这里，我们根据 16S rRNA 基因扩增子序列变异（ASVs），在最初原始的浅层多孔含水层中，跟踪了地表水入侵对微生物群落组成变化的影响，这是在诱导河岸过滤的早期阶段，历时七周。我们进一步分析了七周河岸过滤后的沉积物芯，以了解河流水带来的 ASVs 的印记。地表水入侵的开始导致了分类群的丧失和群落组成的显著变化，这表明初始含水层微生物群落的抗干扰能力较低。源追踪分析显示，地下水中原位 ASVs 的比例一般<25%，但在强降水期间局部可达 62%。然而，变分分配表明，由于渗透河水引起的环境条件变化导致的物种分选，对含水层微生物群落组成变化的河流水带来的 ASVs 的扩散的影响总体上超过了扩散的影响。含水层沉积物中原位 ASVs 的比例<0.5%，表明在研究过程中从河流输送到含水层的分类群主要作为浮游微生物存在于地下水中。我们的研究表明，地下水微生物群落对地表水入侵引起的环境条件变化反应敏感，而由河流水带来的分类群的大量涌入所产生的质量效应则相对较小。
