Concentration-runoff relationships of contrasting small mountainous rivers in the Pacific Northwest, USA: Insights into the weathering of rhenium relative to other weathering products
Concentration-runoff relationships of contrasting small mountainous rivers in the Pacific Northwest, USA: Insights into the weathering of rhenium relative to other weathering products
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DOI：
10.1016/j.gca.2022.09.036
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发表时间：
2022-10-26
影响因子：
5
通讯作者：
Pett-Ridge, Julie C.
中科院分区：
文献类型：
--
作者：
Ghazi, Layla;Goni, Miguel;Pett-Ridge, Julie C.
本研究使用来自美国太平洋西北部的 Eel 河和 Umpqua 河这两个对比鲜明的山区流域的河流样本，研究了溶解铼 (Re) 浓度与径流函数的关系。这些流域在大小、流量、气候和植被方面具有许多共同的关键特征，但由于其构造环境以及抬升和侵蚀率的差异，它们的产沙量存在 15 倍的差异。我们评估主要阳离子、阴离子、溶解无机碳、包括Re在内的选定微量元素的浓度-径流(C-R)关系和变异系数比率(CVC/CVR)以及87Sr/Sr-86比率。最近的研究概述了铼作为古代/化石有机物氧化示踪剂的潜力，因为它与岩石中的成岩碳（OCpetro）密切相关。在 Eel 河和 Umpqua 河中，我们的测量表明，Re 的行为与根据大气输入校正的主要风化衍生溶质类似，例如 Ca2+*、Mg2+* 和 Na+*，随着径流的增加，在所有支流中都有适度的稀释。铼的行为与其他微量元素（例如 Mo 和 U）不同，也与生物循环营养素（例如 NO3 -、PO43- 和 K+*）不同，这表明铼在来源、溶质生成机制和流动路径方面存在差异。铼的行为也与胶体不同，胶体的浓度随着径流的增加而增加。我们发现针对大气输入进行校正的 Re 和硫酸盐 (SO42-*) 具有明显的 C-R 关系，其中 SO42-* 随着径流的增加而经历更大的稀释。这意味着铼并非主要来自硫化物风化作用，这使得这些流域基岩中的原生基岩矿物和 OCpetro 可能成为溶解铼释放的主要来源。在平均流量下，Eel 河中的 Re 浓度 (3.5 pmol L-1) 是 Umpqua 河中的 Re 浓度 (1.5 pmol L-1) 的两倍多。此外，对具有相似基岩但侵蚀速率显着差异的两个支流流域进行比较表明，Bull Creek（侵蚀速率为0.5 mm yr(-1)）相对于Elder Creek（侵蚀速率为0.2 mm yr(-1)），铼浓度较高。这项研究的结果表明，Eel 和 Umpqua 河流域中溶解的 Re 很可能来自原生矿物溶解或 OCpetro 氧化，并且在侵蚀率较高的地区，Re 通量较高，表明构造环境是控制 Re 释放并因此控制 OCpetro 氧化的因素之一。(C) 2022 Elsevier Ltd. 保留所有权利。
This study examines dissolved rhenium (Re) concentrations as a function of water runoff using river samples from two contrasting mountainous watersheds, the Eel and Umpqua Rivers in the Pacific Northwest, USA. These watersheds share many key characteristics in terms of size, discharge, climate, and vegetation, but they have a 15-fold difference in sediment yield due to differences in their tectonic setting and uplift and erosion rates. We evaluate concentration-runoff (C-R) relationships and ratios of coeffi-cients of variation (CVC/CVR) for major cations, anions, dissolved inorganic carbon, selected trace ele-ments including Re, and 87Sr/Sr-86 ratios. Recent research outlines the potential of Re to serve as a tracer for the oxidation of ancient/fossil organic matter because of its close association with petrogenic carbon (OCpetro) in rocks. In both the Eel and Umpqua Rivers, our measurements show that Re behaves similarly to major weathering derived-solutes corrected for atmospheric input, such as Ca2+*, Mg2+*, and Na+* with modest dilution across all tributaries with increasing runoff. Rhenium behaves dissimilarly from other trace elements, such as Mo and U, and is also dissimilar to biologically-cycled nutrients, such as NO3 -, PO43-, and K+*, suggesting differences in sources, solute generation mechanisms, and flowpaths. Rhenium behavior is also distinct from that of colloids, which have increasing concentrations with increasing runoff. We find that Re and sulfate corrected for atmospheric input (SO42-*) have distinct C-R relationships, in which SO42-* undergoes greater dilution with increasing runoff. This implies that Re is not dominantly sourced from sulfide weathering, which leaves primary bedrock minerals and OCpetro hosted in bedrock of these watersheds as the likely dominant sources of dissolved Re release. At mean discharge, Re concentration in the Eel river (3.5 pmol L-1) is more than two times greater than Re concentrations in the Umpqua River (1.5 pmol L-1). Furthermore, comparison of two tributary watersheds with similar bedrock but marked differences in erosion rates show higher Re concentrations in Bull Creek (erosion rate of 0.5 mm yr(-1)) relative to Elder Creek (erosion rate of 0.2 mm yr(-1)). The results of this study suggest that dissolved Re in the Eel and Umpqua River basins is likely derived from primary mineral dis-solution or OCpetro oxidation, and Re fluxes are higher in areas with higher erosion rates, suggesting that tectonic setting is one factor that controls Re release and therefore OCpetro oxidation.(C) 2022 Elsevier Ltd. All rights reserved.