Dissolved silica mobilization in the conterminous USA
Dissolved silica mobilization in the conterminous USA
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DOI：
10.1016/j.chemgeo.2009.11.008
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发表时间：
2010-02-15
期刊：
影响因子：
3.9
通讯作者：
Middelkoop, Hans
中科院分区：
文献类型：
--
作者：
Jansen, Nils;Hartmann, Jens;Middelkoop, Hans
硅酸盐风化作用调动了“新鲜的”溶解二氧化硅（DSi）。在大陆或全球尺度上，化学风化动员DSi的主要因素尚未得到令人满意的量化。此外，所提出的因素的区域差异对大规模DSi动员的影响没有得到适当的评估。开发了一个大陆尺度的、面向过程的、DSi动员的经验模型来评估这一研究差距。该模型是根据来自毗邻美国的142个监测站的河流化学数据进行校准的，这些监测站是根据其集水区的人为和水体影响最小而选择的。流域平均面积为3890公里(2)。观测到的流域平均DSi产出量为2.68 t SiO2 km(-2) a（-1）。该模型根据流域属性（即气候、岩性、土地覆盖和形态）计算DSi产量。作为模型的岩性源数据，绘制了新的北美岩性图。新地图的高空间分辨率允许评估岩性，地图范围小至0.5公里(2)。平均岩性多边形尺寸为75 km(2)。开发的多岩性、非线性、年度DSi动员的集总模型描述了89%的DSi产量观测方差。它使用岩性比例和径流作为预测指标。随着径流的增加，不同岩性的DSi产量增加不同。基性火成岩相对于给定的径流显示出最高的DSi产量。固结的沉积岩性类产出DSi的顺序与它们定义的硅含量相反。在所有岩性类别中，每次径流中最少的DSi是从酸性深成岩中调动的。除了这两个主要预测因子外，模型分析还为温度和土地覆盖对DSi动员的影响提供了证据。与已有研究的比较表明，DSi迁移的控制因素存在区域差异。因此，在不同地区校准的研究结果表明，对于可比较的岩性类别，DSi产量存在显著差异。这强调需要对全球发展创新动员模式进行区域校准。(C) 2009 Elsevier B.V.版权所有
Silicate weathering mobilizes "fresh" dissolved silica (DSi). The major factors governing DSi mobilization by chemical weathering on continental or global scales have not been satisfactorily quantified. Furthermore, influence of regional variations of proposed factors on large scale DSi mobilization is not properly assessed. A continental-scale, process-oriented, empirical model for DSi mobilization is developed to assess this research gap. The model is calibrated on river chemistry data from 142 monitoring stations from the conterminous USA, selected for minimal arithropogenic and water-body influence in their catchments. The average area of the catchments is 3890 km(2). The average observed DSi yield of the catchments is 2.68 t SiO2 km(-2) a(-1). The model calculates DSi yield as subject to catchment attributes, i.e. climate, lithology, land cover and morphology. As lithological source data for the model, a new lithological map of North America was developed. The high spatial resolution of the new map allows assessment of lithology, classes with mapped extents as small as 0.5 km(2). The average lithology polygon size is 75 km(2).The developed multi-lithological, non-linear, lumped model for annual DSi mobilization describes 89% of the observed variance of DSi yield. It uses lithology proportion and runoff as predictors. With runoff, DSi yield increases differently for individual lithological classes. Basic igneous rocks show the highest DSi yields with respect to a given runoff. Consolidated sedimenary lithological classes yield DSi in the reversed order of their defined silicon contents. Of all lithological classes, the least DSi per runoff is mobilized from acid plutonic rocks.Apart from the two major predictors, analysis of the model also provides evidence for an influence of temperature and land cover on DSi mobilization. Comparison with existing studies shows that controlling factors on DSi mobilization vary regionally. Thus, studies calibrated in different regions result in significantly different DSi yields for comparable lithological classes. This emphasizes the need for global DSi mobilization models to be regionally calibrated. (C) 2009 Elsevier B.V. All rights reserved.