Climate Controls on River Chemistry
Climate Controls on River Chemistry
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DOI：
10.1029/2021ef002603
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发表时间：
2022-05
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影响因子：
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通讯作者：
Li Li-Li;Bryn Stewart;Wei Zhi;K. Sadayappan;S. Ramesh;Devon Kerins;Gary Sterle;A. Harpold;J. Perdrial
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文献类型：
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作者：
Li Li-Li;Bryn Stewart;Wei Zhi;K. Sadayappan;S. Ramesh;Devon Kerins;Gary Sterle;A. Harpold;J. Perdrial
气候如何控制河流化学？现有的文献已经广泛地研究了河流化学对短期天气条件的响应，从事件到季节尺度。长期基线河流化学的模式和驱动因素仍然知之甚少。在这里，我们编译和分析化学数据从506受影响最小的河流（412，801个数据点）在毗连的美国（CAMELS‐Chem），以确定河流化学的模式和驱动因素。尽管不同的来源和不同的反应特性，一个普遍的模式出现了16个主要溶质在大陆规模。它们的长期平均浓度（Cm）随平均排放量（Qm）而降低，在干旱气候中浓度升高，在潮湿气候中浓度较低，表明与当地关键区特征（如岩性和地形）相比，气候具有压倒性的调节作用。为了理解CmQm模式，一个简约的流域反应器模型解决了汇集水文（存储-排放关系）和地球化学反应理论从传统上独立的学科。长期稳态解的推导导致CmQm关系的幂律形式。该模型阐明了两个相互竞争的过程，确定平均溶质浓度：溶质生产的地下水地球化学和化学风化反应，溶质出口（或去除）的平均排放量，水冲洗能力由气候和植被。换句话说，流域的功能主要是在干旱气候中产生和积累溶质的反应器，以及在潮湿气候中输出溶质的运输者。通过空间换时间的替代，这些结果表明，在气候变暖导致河流流量减少的地方，即使没有人为干扰，溶质浓度也会升高，威胁水质和水生生态系统。因此，在全球计算未来气候风险时应考虑水质恶化。
How does climate control river chemistry? Existing literature has examined extensively the response of river chemistry to short‐term weather conditions from event to seasonal scales. Patterns and drivers of long‐term, baseline river chemistry have remained poorly understood. Here we compile and analyze chemistry data from 506 minimally impacted rivers (412,801 data points) in the contiguous United States (CAMELS‐Chem) to identify patterns and drivers of river chemistry. Despite distinct sources and diverse reaction characteristics, a universal pattern emerges for 16 major solutes at the continental scale. Their long‐term mean concentrations (Cm) decrease with mean discharge (Qm), with elevated concentrations in arid climates and lower concentrations in humid climates, indicating overwhelming regulation by climate compared to local Critical Zone characteristics such as lithology and topography. To understand the CmQm pattern, a parsimonious watershed reactor model was solved by bringing together hydrology (storage–discharge relationship) and biogeochemical reaction theories from traditionally separate disciplines. The derivation of long‐term, steady state solutions lead to a power law form of CmQm relationships. The model illuminates two competing processes that determine mean solute concentrations: solute production by subsurface biogeochemical and chemical weathering reactions, and solute export (or removal) by mean discharge, the water flushing capacity dictated by climate and vegetation. In other words, watersheds function primarily as reactors that produce and accumulate solutes in arid climates, and as transporters that export solutes in humid climates. With space‐for‐time substitution, these results indicate that in places where river discharge dwindles in a warming climate, solute concentrations will elevate even without human perturbation, threatening water quality and aquatic ecosystems. Water quality deterioration therefore should be considered in the global calculation of future climate risks.