Concentration-discharge relationships reflect chemostatic characteristics of US catchments
Concentration-discharge relationships reflect chemostatic characteristics of US catchments
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DOI：
10.1002/hyp.7315
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发表时间：
2009-06-30
影响因子：
3.2
通讯作者：
Clow, David W.
中科院分区：
文献类型：
--
作者：
Godsey, Sarah E.;Kirchner, James W.;Clow, David W.
浓度-流量关系已被广泛用作控制径流化学的水化学过程的线索。在这里，我们研究主要由矿物风化产生的溶质在59个地球化学不同的美国集水区的浓度-排放关系。我们发现，这些集水区表现出近恒化行为，其流浓度的风化产物，如钙，镁，钠，硅通常变化的因素只有3至20，而放电变化了几个数量级。在年际时间尺度上也观察到类似的模式。这种行为意味着，在溪流中的溶质浓度不是由一个简单的稀释固定的溶质通量的可变通量的水，和溶质的生产和/或动员率必须几乎成比例的水通量，无论是在风暴和年际的时间尺度。我们比较了这些集水区的浓度-流量关系的几个简单的水文和地球化学模型的预测。这些模型中的大多数可以被迫近似拟合观察到的浓度-放电关系，但通常只能通过假设不切实际或内部不一致的参数值。我们提出了一个新的模型，也适合的数据，可能更强大。我们建议可能的测试的新模型为未来的研究。在广泛变化的排放量下，浓度的相对稳定性可能有助于使水生环境适合居住。这也意味着河流中风化溶质的通量，从而碱度的海洋通量，主要是由水通量。因此，水文学可能是调节气候变化的海洋碱性反馈的主要驱动力。版权所有（C）2009约翰威利父子有限公司
Concentration-discharge relationships have been widely used as clues to the hydrochemical processes that control runoff chemistry. Here we examine concentration-discharge relationships for solutes produced primarily by mineral weathering in 59 geochemically diverse US catchments. We show that these catchments exhibit nearly chemostatic behaviour; their stream concentrations of weathering products such as Ca, Mg, Na, and Si typically vary by factors of only 3 to 20 while discharge varies by several orders of magnitude. Similar patterns are observed at the inter-annual time scale. This behaviour implies that solute concentrations in stream water are not determined by simple dilution of a fixed solute flux by a variable flux of water, and that rates of solute production and/or mobilization must be nearly proportional to water fluxes, both on storm and inter-annual timescales. We compared these catchments' concentration-discharge relationships to the predictions of several simple hydrological and geochemical models. Most of these models can be forced to approximately fit the observed concentration-discharge relationships, but often only by assuming unrealistic or internally inconsistent parameter values. We propose a new model that also fits the data and may be more robust. We suggest possible tests of the new model for future studies. The relative stability of concentration under widely varying discharge may help make aquatic environments habitable. It also implies that fluxes of weathering solutes in streams, and thus fluxes of alkalinity to the oceans, are determined primarily by water fluxes. Thus, hydrology may be a major driver of the ocean-alkalinity feedback regulating climate change. Copyright (C) 2009 John Wiley & Sons, Ltd.