Seasonal hyporheic dynamics control coupled microbiology and geochemistry in Colorado River sediments
Seasonal hyporheic dynamics control coupled microbiology and geochemistry in Colorado River sediments
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DOI：
10.1002/2016jg003527
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发表时间：
2016-12-01
影响因子：
3.7
通讯作者：
Wilkins, Michael J.
中科院分区：
文献类型：
--
作者：
Danczak, Robert E.;Sawyer, Audrey H.;Wilkins, Michael J.
河床微生物群落在许多流域生态系统功能中发挥着巨大的作用，包括有机碳的处理，氮的循环和金属流动性的改变。微生物群落的结构和活性部分取决于河流-地下水交换或潜流交换所设定的地球化学条件。为了评估河流-地下水混合的季节性变化如何影响这些人口在融雪为主的河流系统，垂直沉积物和孔隙水剖面采样在三个时间点在一个位置在低流区的科罗拉多河和分析地球化学测量，16 S rRNA基因测序和生态建模。含氧河水渗透到地下最深的高峰期河流排放，而在基流条件下，缺氧地下水占主导地位的浅层。因此，在70厘米厚的间隔，河床沉积物暴露于季节性波动的氧化还原条件和托管的微生物种群统计学上不同于那些在较浅和较深的位置。此外，该区域内的微生物种群在采样时间点上表现出最大的动态性，这强调了潜流混合在限制微生物丰度方面发挥的关键作用。考虑到这种混合效应，我们预计，未来的变化，在美国西部山区，半干旱流域的河流流量可能会影响微生物群落结构和功能在河床环境中，在河岸地区的生态地球化学过程的潜在影响。
Riverbed microbial communities play an oversized role in many watershed ecosystem functions, including the processing of organic carbon, cycling of nitrogen, and alterations to metal mobility. The structure and activity of microbial assemblages depend in part on geochemical conditions set by river-groundwater exchange or hyporheic exchange. To assess how seasonal changes in river-groundwater mixing affect these populations in a snowmelt-dominated fluvial system, vertical sediment and pore water profiles were sampled at three time points at one location in the hyporheic zone of the Colorado River and analyzed by using geochemical measurements, 16S rRNA gene sequencing, and ecological modeling. Oxic river water penetrated deepest into the subsurface during peak river discharge, while under base flow conditions, anoxic groundwater dominated shallower depths. Over a 70 cmthick interval, riverbed sediments were therefore exposed to seasonally fluctuating redox conditions and hosted microbial populations statistically different from those at both shallower and deeper locations. Additionally, microbial populations within this zone were shown to be the most dynamic across sampling time points, underlining the critical role that hyporheic mixing plays in constraining microbial abundances. Given such mixing effects, we anticipate that future changes in river discharge in mountainous, semiarid western U.S. watersheds may affect microbial community structure and function in riverbed environments, with potential implications for biogeochemical processes in riparian regions.