The geochemistry of river particulates from the continental USA: Major elements
The geochemistry of river particulates from the continental USA: Major elements
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DOI：
10.1016/s0016-7037(97)00172-5
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发表时间：
1997-08-01
影响因子：
5
通讯作者：
Canfield, DE
中科院分区：
文献类型：
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作者：
Canfield, DE
从美国大陆的23条河流中收集了河流颗粒物。河流主要流经大型盆地（盆地面积从2.1 x 10（3）到2970 X 10（3）km（2）），这些盆地由混合岩性组成，并跨越广泛的气候条件，如空气和地下水温度、降水和径流的巨大变化所证明的。悬浮颗粒物中的有机和无机碳，以及主要元素铝，铁，锰，钾，硅，钙，镁和钠进行了分析。还确定了悬浮泥沙负荷在采样时，颗粒表面积和粒度分布。五年平均河水化学和悬浮泥沙浓度，从美国地质勘探局供水报告：也包括作为支持信息。颗粒化学系统地随径流率而变化，高径流河流输送最严重的改变颗粒，低径流河流携带最少的改变。蚀变程度由难熔、非流动元素Al和Fe集中到颗粒中的程度以及最易风化元素Na、Ca和Mg达到的程度来表示。总体而言，元素对淋溶的敏感性与前人对元素迁移率对风化作用的描述是一致的，并建立了一个简单的预测模型来探讨和解释观测到的颗粒组成与径流之间的趋势。因此，河流颗粒物的元素组成可以由表达式PCOi = [（Prop（i））TM-DCOi]/SS给出，其中PCOi是元素i的浓度（作为氧化物）在河流颗粒中，Prop（i）是i的比例在未风化岩石中，DCOi（作为氧化物）是i的溶解浓度TM是溶解在河水中的总岩石衍生质量，SS是悬浮泥沙浓度。为了利用这个方程，首先开发了一个模型来预测河流溶质的浓度与输入的温度，降水量和数量有限的风化参数。将该溶质模型与上述颗粒组成预测方程相结合，发现颗粒组成与径流之间的观测趋势需要SS随径流增加而减少的特殊情况。因此，河流颗粒物的组成取决于径流和温度的气候参数（因为它们控制溶解的河流化学）和非气候参数，包括海拔，地形，构造和流域面积，控制河流的SS负荷。版权所有（C）1997 Elsevier Science Ltd.
River particulates have been collected from twenty-three rivers from throughout the continental USA. The rivers drain mostly large basins (basin areas range from 2.1 x 10(3) to 2970 X 10(3) km(2)) composed of mixed lithologies, and spanning a wide range of climatic conditions as evidenced by a large variation in air and ground water temperatures, precipitation, and runoff. Suspended particulates have been analyzed for organic and inorganic carbon, as well as the major elements Al, Fe, Mn, K, Si, Ca, Mg, and Na. Also determined were suspended sediment loads at the time of sampling, particle surface areas, and grain size distributions. Five-year average river water chemistry and suspended sediment concentrations, obtained from USGS water supply reports: are also included as supporting information. Particle chemistry systematically Varies with rates of runoff, with high runoff rivers transporting the most heavily altered particulates and low runoff rivers carrying the least altered. Degrees of alteration are indicated by the extent to which the refractory, nonmobile elements Al and Fe are concentrated into the particulates and the extent to which the most easily weathered elements Na, Ca, and Mg have been reached. Overall, the susceptibility of elements towards leaching is consistent with numerous previous descriptions of element mobility on weathering.A simple predictive model has been developed to explore and explain the observed trends between particle composition and river runoff. Thus, the elemental composition of riverine particulates may be given by the expression PCOi = [(Prop(i))TM-DCOi]/SS, where PCOi is the concentration of element i (as the oxide) in a riverine particulate, Prop(i) is the proportion of i (as the oxide) in unweathered rock, DCOi is the dissolved concentration of i (as the equivalent oxide), TM is the total rock derived mass dissolved in river water, and SS is suspended sediment concentration. To utilize this equation, a model was first developed to predict the concentration of river solutes with the input of temperature, precipitation, and a limited number of weathering parameters. Combining this solute model with the above predictive equation for particle composition, it was discovered that the observed trends between particle composition and runoff require the special circumstance of decreasing SS with increasing runoff. Hence, the composition of river particulates depends both on the climate parameters of runoff and temperature (as they control dissolved river chemistry) and the nonclimate parameters including elevation, relief, tectonics, and basin area that control the SS load of rivers. Copyright (C) 1997 Elsevier Science Ltd.