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Early diagenesis and accumulation of redox-sensitive elements in East Siberian Arctic Shelves
Marine Geology ( IF 2.6 ) Pub Date : 2020-08-05 , DOI: 10.1016/j.margeo.2020.106309
Li Li , Yanguang Liu , Xiaojing Wang , Limin Hu , Gang Yang , Hongmin Wang , A.A. Bosin , A.S. Astakhov , Xuefa Shi

The Arctic shelf makes up half of the area within the Arctic Ocean. It plays an important role in the global carbon cycle, whilst its part in the recycling process of redox-sensitive elements (RSEs) is still not clear. This study has selected nine sediment cores, 30 to 40 cm in length, covering a wide area over the East Siberian Arctic Shelves (ESAS) and analyzed a suite of RSEs (S, Mn, Mo, U, V, Cd) in the sediments, along with Al, Fe, total organic carbon (TOC), grain size, and sedimentation rate. The redox environment in surface sediments was clearly divided based on the S and Mn contents of the cores, ranging from being more oxidized on the western East Siberian Sea shelf, to more reduced on the Chukchi Sea shelf. TOC also showed an increasing trend eastward in the study region. Statistically significant correlations were found between Cd and S, V and Fe, Mo and Mn, and U and TOC, implying their close relationships during early diagenetic processes at the sediment-water interface. Across the study area, authigenic accumulation occurred for all RSEs, except Mn. The estimated authigenic accumulation fluxes for Mo, U, V, and Cd over the entire ESAS are 0.21 ± 0.09, 0.086 ± 0.043, 11.0 ± 9.2 and 0.019 ± 0.014 × 108 mol y−1, respectively, which are comparable to values reported in suboxic marginal sediments for Mo, U, and Cd, but exceptionally high for V. Although the sampling resolution was coarse and there are uncertainties in the sedimentation rates and detrital background values of V, we propose the authigenic accumulation flux for V on the broad and shallow ESAS may be a significant but missing sink term for the global V cycle.



中文翻译:

西伯利亚北极大陆架的早期成岩作用和氧化还原敏感元素的积累

北极大陆架占北冰洋面积的一半。它在全球碳循环中起着重要作用,而其在氧化还原敏感元素(RSE)回收过程中的作用仍不清楚。这项研究选择了9个长30至40厘米长的沉积物核心,覆盖了整个西伯利亚北极大陆架(ESAS),并分析了沉积物中的一系列RSE(S,Mn,Mo,U,V,Cd)以及Al,Fe,总有机碳(TOC),晶粒尺寸和沉降速率。根据岩心中的S和Mn含量,明显区分了表层沉积物中的氧化还原环境,范围从西西伯利亚东海陆架被氧化得更多,到楚科奇海陆架被氧化得更多。在研究区域内,TOC也显示出向东增加的趋势。在镉和硫,钒和铁,钼和锰以及铀和有机碳之间发现了具有统计学意义的相关性,这表明它们在沉积物-水界面的早期成岩过程中有着密切的关系。在整个研究区域中,除锰外,所有RSE均发生了自生积累。在整个ESAS中,Mo,U,V和Cd的估计自生累积通量为0.21±0.09、0.086±0.043、11.0±9.2和0.019±0.014×10分别为8  mol y -1,与Mo,U和Cd在低氧边缘沉积物中报道的值相当,但对于V则异常高。尽管采样分辨率很粗糙,并且沉积速率和碎屑本底值存在不确定性关于V,我们建议在宽和浅的ESAS上,V的自生累积通量可能是全局V周期的一个重要但缺失的下沉项。

更新日期:2020-08-05
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