The influence of river-derived particles on estuarine and marine elemental cycles: evidence from lithium isotopes
The influence of river-derived particles on estuarine and marine elemental cycles: evidence from lithium isotopes
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DOI：
10.1016/j.gca.2023.08.015
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发表时间：
2023-08
影响因子：
5
通讯作者：
Chun-Yao Liu;David J. Wilson;E. Hathorne;Antao Xu;Philip A. E. Pogge von Strandmann
中科院分区：
文献类型：
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作者：
Chun-Yao Liu;David J. Wilson;E. Hathorne;Antao Xu;Philip A. E. Pogge von Strandmann
为了研究大型河口河流沉积物的变化及其对元素循环和全球气候的影响，本研究分析了锂（Li）同位素和元素浓度（例如，Li，Na，Mg，K，Ca，Fe和Al）的溶解负荷和沉积物负荷的不同阶段（即，可交换的，碳酸盐，氧化物，粘土和残留物）在亚马逊河口。结果表明，河流沉积物中的溶解负荷，主要是由于阳离子保留在次生粘土中的锂。通过模拟Li的质量平衡和同位素分馏，我们估计亚马逊河口的河流沉积物从溶解负荷中获得3-4 μg/g Li，Li同位素分馏因子（α粘土溶液）约为0.975。就整个亚马逊河口而言，河流沉积物从溶解负荷中去除约3.6-4.8 × 109 g/年的Li。具体而言，约1.0-1.7 × 108克/年的锂从河水中去除（约占亚马逊河溶解锂排放通量的1.8-3.0%），约3.5-4.7 × 109克/年的锂从海水中去除，这代表了海洋的显著下沉。这河口锂汇可能与大陆侵蚀速率，因此，大陆风化和侵蚀制度不仅可以影响河流锂输入，但也可能直接影响锂汇，导致在海洋中的锂预算和同位素组成的双重控制。
To examine the alteration of river-derived sediments through a large estuary and the implications for elemental cycling and global climate, this study analyses lithium (Li) isotopes and elemental concentrations (e.g., Li, Na, Mg, K, Ca, Fe and Al) of both the dissolved load and different phases of the sediment load (i.e., exchangeable, carbonate, oxide, clay and residue) in the Amazon estuary. The results show that river-derived sediments remove Li from the dissolved load, largely due to cation retention in secondary clays. By modelling the Li mass-balance and isotope fractionation, we estimate that the river-derived sediments gain 3–4 μg/g Li from the dissolved load in the Amazon estuary, with a Li isotope fractionation factor (αclay-solution) of approximately 0.975. Considering the whole Amazon estuary, the river-derived sediments remove around 3.6–4.8 × 109g/yr of Li from the dissolved load. Specifically, around 1.0–1.7 × 108g/yr of Li is removed from river water (∼1.8–3.0% of the dissolved Li discharge flux of the Amazon River) and around 3.5–4.7 × 109g/yr of Li is removed from seawater, which represents a significant sink from the ocean. This estuarine Li sink is likely to be related to continental erosion rates; thus, continental weathering and erosion regimes could influence not only riverine Li input, but could also directly affect the Li sink, leading to a dual control on the Li budget and isotope composition in the ocean.