Emergent Scaling of Dissolved Oxygen (DO) in Freshwater Streams Across Contiguous USA
Emergent Scaling of Dissolved Oxygen (DO) in Freshwater Streams Across Contiguous USA
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DOI：
10.1029/2022wr032114
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发表时间：
2023-01
影响因子：
5.4
通讯作者：
O. Abdul‐Aziz;A. Gebreslase
中科院分区：
文献类型：
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作者：
O. Abdul‐Aziz;A. Gebreslase
溶解氧(DO)反映了河流的整体水质和生态系统健康状况。我们调查了美国毗邻地区淡水(非沿海)溪流中主要环境驱动因素对溶解氧的紧急影响。获得了1998-2015年间美国86条河流每月至季度采样频率的可用数据。数据分析表明，水温(Tw)和pH(二氧化碳的替代物)主导着淡水溪流中DO浓度的关键环境过程成分。“气候”过程成分(包括Tw和净辐射)对DO的控制作用分别是“生物地球化学”成分(总氮、总磷、pH和比电导率)和“水-大气”交换成分(水流量和大气压力)的9倍，∼3和∼对DO的控制作用比“生物地球化学”成分(总氮、总磷、pH和比电导率)和“水-大气”交换成分(水流和大气压力)强9倍。河流DO的主要气候控制与排水流域的高植被(平均∼53%)和陡坡(∼10%)有关，尽管存在显著的农业用地(∼35%)。然后根据Tw(K)和pH建立了一个可接受地预测DO(mg/L)的紧急幂定律标度关系，其近似指数分别为−15/2和1/2(纳什-萨克利夫效率=0.72-0.73)。标度定律显示了潜在的组织原理，如随着温度和营养物质的增加，由于溶解减少和新陈代谢呼吸增加而导致的河流DO的枯竭。比例定律在美国的不同河流中持续存在，代表着气候、水文、生物地球化学和土地利用/覆盖的梯度。这些发现将有助于理解和管理美国及其他地区淡水溪流的水质和生态系统健康。
Dissolved oxygen (DO) indicates the overall stream water quality and ecosystem health. We investigated emergent scaling of DO with the dominant environmental drivers in freshwater (non‐coastal) streams across the contiguous United States. Available data of monthly to quarterly sampling frequencies during 1998–2015 were obtained for 86 U.S. streams. Data analytics indicated water temperature (Tw) and pH (a proxy of carbon dioxide) dominating the key environmental process components of DO concentrations in the freshwater streams. The “climatic” process component (comprising Tw and net radiation) had, respectively, ∼3 and ∼9 times stronger control on DO than the “biogeochemical” (total nitrogen, total phosphorus, pH, and specific conductivity) and “hydro‐atmospheric” exchange (stream flow and atmospheric pressure) components. The predominant climatic control on stream DO was linked to the high extent of vegetated land (on average ∼53%) and steep slope (∼10%) in the draining watersheds, despite the notable presence of agricultural land (∼35%). An emergent power law scaling relationship was then developed to acceptably predict DO (mg/l) based on Tw (K) and pH, with the approximate exponents of −15/2 and 1/2, respectively (Nash‐Sutcliffe Efficiency = 0.72–0.73). The scaling law demonstrated the underlying organizing principles such as the depletion of stream DO due to reduced dissolution and increased metabolic respiration with the increasing temperature and nutrients. The scaling law was persistent across the various U.S. streams, representing gradients in climate, hydrology, biogeochemistry, and land use/cover. The findings would help understand and manage water quality and ecosystem health in freshwater streams across the United States and beyond.