Effects of relic low-head dams on stream denitrification potential: seasonality and biogeochemical controls
Effects of relic low-head dams on stream denitrification potential: seasonality and biogeochemical controls
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DOI：
10.1007/s00027-022-00894-z
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发表时间：
2022-09
期刊：
影响因子：
2.4
通讯作者：
Johanna Hripto;S. Inamdar;M. Sherman;E. Peck;A. Gold;S. Bernasconi;K. Addy;M. Peipoch
中科院分区：
文献类型：
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作者：
Johanna Hripto;S. Inamdar;M. Sherman;E. Peck;A. Gold;S. Bernasconi;K. Addy;M. Peipoch
美国本土的大多数水坝都是小型低水头水坝，虽然已不再运行，但会影响当代溪流生态系统的水质。低水头坝对河流脱氮（反硝化）的潜在影响很少被量化，但它们可以成为拆除低水头坝决策过程的重要组成部分。在这里，我们提供了两年期间大西洋中部两座低水头大坝的潜在反硝化率及其生物地球化学控制的新经验数据。我们的结果表明，与同一河流中无水坝的河段相比，低水头水坝并没有增加河床的潜在反硝化作用。在我们的研究地点，尽管水体缺氧（< 50%溶解氧饱和度）和高NO3−和DOC浓度的事件反复发生，但低水头坝上方的潜在反硝化通常较低（15.7 ± 3.5 µg N [kg沉积物]−1h−1）。总体而言，我们在冬季采样期间观察到较高的潜在反硝化作用（平均为 9.2 和 50.1 µg N [kg 沉积物]−1h−1），并且沉积物表面积和有机物含量对大坝上方潜在反硝化率的显着影响。这项研究的结果表明，遗留的低水头大坝对河流生态系统中氮的去除和运输影响有限，并且可以为拆除低水头大坝的决策过程做出贡献。
The majority of dams in the contiguous United States are small, low-head dams that are no longer operational but can influence the water quality of contemporary stream ecosystems. Potential effects of low-head dams on stream nitrogen removal (denitrification) have been rarely quantified, and yet they can be an important part of the decision-making process of removing low-head dams. Here, we provide novel empirical data on potential denitrification rates and their biogeochemical controls above and below two mid-Atlantic low-head dams over a 2-year period. Our results show that low-head dams did not increase streambed potential denitrification in comparison to dam-free sections in the same rivers. In our study sites, potential denitrification above low-head dams was generally low (15.7 ± 3.5 µg N [kg sediment]−1h−1) despite recurring events of water hypoxia (< 50% dissolved oxygen saturation) and high NO3−and DOC concentrations. Overall, we observed higher potential denitrification during winter samplings (9.2 and 50.1 µg N [kg sediment]−1h−1on average) and significant effects of sediment surface area and organic matter content on potential denitrification rates above the dams. Results from this study suggest limited effects of relic low-head dams on nitrogen removal and transport in stream ecosystems, and can contribute to the decision-making process of removing low-head dams.