Hypoxia dynamics and spatial distribution in a low gradient river
Hypoxia dynamics and spatial distribution in a low gradient river
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DOI：
10.1002/lno.11751
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发表时间：
2021-04-23
影响因子：
4.5
通讯作者：
Bernhardt, Emily S.
中科院分区：
文献类型：
--
作者：
Carter, Alice M.;Blaszczak, Joanna R.;Bernhardt, Emily S.
水生生态系统的脱氧是人类世的一个关键特征。越来越多的研究报告称，即使在没有高营养负荷的情况下，河流和源头溪流也存在低氧条件。我们通过检查自 20 世纪 60 年代以来收集的监测记录，并收集沿新希望溪 20 公里段的 DO 饱和度的高分辨率测量结果，检查了北卡罗来纳州皮埃蒙特河流缺氧（溶解氧 [DO] < 50% 饱和于 O-2）的频率。州记录报告了近 11,000 起缺氧事件，总共进行了 140,000 次测量（55 年中占 7.8%）。相比之下，我们在新希望溪的测量表明，通过点测量来评估河流缺氧是非常有问题的。我们提出了评估和比较河流氧状况的新方法。在 2018 年 5 月对 DO 进行的详细纵向调查中，超过 20 公里的测量结果中有 31% 是低氧的。在 3 周的时间内，我们在该段 12 个站点中的 11 个站点在 5%-96% 的时间内经历了缺氧。对几个长期监测点的年际比较表明，即使在特别温暖、低流量的时期，即使在通气良好的河段，缺氧的可能性也很大。这条河内的氧气状况在近乎连续缺氧和近乎连续饱和之间变化，这使我们对淡水生态系统和淡水生态系统之间的二元区别产生了疑问，而我们往往用这种区别来对淡水生态系统进行分类和建模。
Deoxygenation of aquatic ecosystems is a key feature of the Anthropocene. Studies are increasingly reporting low oxygen conditions in rivers and headwater streams even in the absence of high nutrient loads. We examined the frequency of river hypoxia (dissolved oxygen [DO] < 50% saturated in O-2) in the North Carolina Piedmont by examining monitoring records collected since the 1960s, and by collecting high-resolution measurements of DO saturation along a 20 km segment of New Hope Creek. State records reported nearly 11,000 incidences of hypoxia from a total of similar to 140,000 measurements (7.8% over 55 yr). In contrast, our measurements in New Hope Creek suggest that assessing river hypoxia from point measurements is highly problematic. We propose new approaches for evaluating and comparing river oxygen regimes. In a detailed longitudinal survey of DO in May 2018, 31% of measurements over 20 km were hypoxic. Over a 3-week period, 11 of our 12 sites throughout this segment experienced hypoxia 5%-96% of the time. Interannual comparisons for several long-term monitoring sites document significant potential for hypoxia even in well-aerated reaches during particularly warm, low flow periods. Oxygen regimes within this river vary between near continuous hypoxia to near continuous saturation and call into question the binary distinction between lotic and lentic oxygen dynamics with which we tend to categorize and model freshwater ecosystems.