Depositional control on the fate of reactive iron in shelf sediments since the last deglaciation: A case study of the East China Sea

IF 2.6 3区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY
Fanxing Kong , Xiting Liu , Anchun Li , Jiang Dong , Houjie Wang , Guangchao Zhuang , Zihu Zhang , Chao Li
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Abstract

The East China Sea (ECS) is located between the Eurasian continent and the Pacific Ocean with a wide continental shelf, which acts as a potential source of reactive iron in the Western Pacific. However, the source and fate of reactive iron in continental shelf sediments of the ECS remain poorly constrained. Here, we examined the influence of the depositional environment on the fate of reactive iron on the continental shelf of the ECS since the last deglaciation. The contents of redox-sensitive elements (U and Mo) indicate that the sediments in the ECS inner shelf have primarily deposited in oxic and suboxic environments since 18.5 ka. The ratio of reactive iron to total iron (FeHR/FeT) ranges from 0.24 to 0.41, and the ratio of total iron to aluminum (FeT/Al) is approximately 0.55 ± 0.11. These ratios suggest that the majority of reactive iron is derived from fine-grained terrestrial sediments discharged by the Changjiang River. The contents of Fepy and Fecarb exhibit opposite trends with depth in the core, indicating competition between carbonate (bicarbonate) ions and sulfide ions for ferrous ions. This competition is primarily controlled by the depositional environment and redox state since 18.5 ka. The Fecarb is the dominant iron speciation throughout the core sediments, but its abundance declined since 13.2 ka when the ECS inner shelf was influenced by seawater transgression due to deglacial sea-level rise. The Fepy content reached its maximum when the ECS inner shelf was fully flooded. Our study highlights the depositional control on the source-sink processes of reactive iron, providing new insights into the fate of reactive iron on continental shelves in response to environmental evolution.

末次冰期以来陆架沉积物中活性铁命运的沉积控制:东海案例研究
中国东海(ECS)位于欧亚大陆和太平洋之间,大陆架宽阔,是西太平洋活性铁的潜在来源。然而,对东海大陆架沉积物中活性铁的来源和归宿仍缺乏深入研究。在此,我们研究了自上一次脱冰期以来沉积环境对 ECS 大陆架活性铁归宿的影响。氧化还原敏感元素(铀和钼)的含量表明,自18.5 ka年以来,ECS内大陆架的沉积物主要沉积在缺氧和亚缺氧环境中。活性铁与总铁的比率(FeHR/FeT)在 0.24 至 0.41 之间,总铁与铝的比率(FeT/Al)约为 0.55 ± 0.11。这些比率表明,大部分活性铁来自长江排放的细粒陆相沉积物。Fepy和Fecarb的含量随着岩芯深度的增加呈现相反的趋势,表明碳酸盐(碳酸氢盐)离子和硫化物离子之间对亚铁离子的竞争。这种竞争主要受 18.5 ka 以来的沉积环境和氧化还原状态的控制。在整个岩芯沉积物中,Fecarb 是最主要的铁离子,但自 13.2 ka 年以来,由于冰期海平面上升,ECS 内大陆架受到海水倒灌的影响,Fecarb 的含量有所下降。当 ECS 内大陆架被完全淹没时,Fepy 含量达到最大值。我们的研究强调了沉积对活性铁源-汇过程的控制,为了解活性铁在大陆架上随环境演变的命运提供了新的视角。
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来源期刊
Marine Geology
Marine Geology 地学-地球科学综合
CiteScore
6.10
自引率
6.90%
发文量
175
审稿时长
21.9 weeks
期刊介绍: Marine Geology is the premier international journal on marine geological processes in the broadest sense. We seek papers that are comprehensive, interdisciplinary and synthetic that will be lasting contributions to the field. Although most papers are based on regional studies, they must demonstrate new findings of international significance. We accept papers on subjects as diverse as seafloor hydrothermal systems, beach dynamics, early diagenesis, microbiological studies in sediments, palaeoclimate studies and geophysical studies of the seabed. We encourage papers that address emerging new fields, for example the influence of anthropogenic processes on coastal/marine geology and coastal/marine geoarchaeology. We insist that the papers are concerned with the marine realm and that they deal with geology: with rocks, sediments, and physical and chemical processes affecting them. Papers should address scientific hypotheses: highly descriptive data compilations or papers that deal only with marine management and risk assessment should be submitted to other journals. Papers on laboratory or modelling studies must demonstrate direct relevance to marine processes or deposits. The primary criteria for acceptance of papers is that the science is of high quality, novel, significant, and of broad international interest.
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