南海典型断面表层沉积物中氧化还原敏感元素的分布特征及其控制因素

Distribution pattern and controlling factors of redox sensitive elements in the surface sediments from four typical transects in the South China Sea

  • 摘要: 氧化还原敏感元素在环境研究中发挥着日益重要的作用,然而对于海底表层沉积物中氧化还原敏感元素的分布规律与特征的研究鲜有涉及。本文以采集自南海4条典型断面(18°N、10°N、6°N、113°E)的75个表层沉积物样品为研究对象,通过主量元素和微量元素(含氧化还原敏感元素Mo、V、U)分析,并结合沉积物粒度、元素富集系数等数据,探讨了表层沉积物中氧化还原敏感元素的分布特征及其控制因素。结果表明,研究区每个断面中的V、U含量变化趋势十分相似,Mo含量变化与V、U的总体变化趋势相近,但Mo在断面上的变化波动比V、U更强烈。4条断面中Mo平均含量表现出明显富集,除了V在断面Ⅰ中表现为轻度富集外,V和U平均含量都表现为亏损。影响沉积物中Mo、V、U含量分布的因素主要包括陆源碎屑含量、生物碳酸盐含量、细粒沉积物的吸附作用和氧化还原环境等。所有断面中V和U的含量分布主要受控于陆源碎屑组分,同时也受到生物碳酸盐含量和细粒沉积物的吸附作用的影响,氧化还原环境对其含量影响较小,受环境影响的自生组分含量较低。Mo的含量分布主要受控于海底氧化还原环境,陆源碎屑组分的贡献和细粒沉积物吸附作用的影响较小,受环境影响的自生组分含量较高。西南次海盆的Mo含量及其富集系数都较低,可能是由于西南次海盆的底流活动使其海底存在氧化环境所致。

     

    Abstract: Redox sensitive elements play an increasingly important role in environmental analysis. However, few studies have been devoted so far to the distribution pattern of the redox sensitive elements in the seafloor surface sediments. In this paper, seventy-five surface sediment samples were collected and analyzed from the four representative transects in the South China Sea along 18°N, 10°N, 6°N, and 113°E respectively. The contents of main elements and trace elements (including Mo, V, and U) are measured in addition to grain sizes of sediments and enrichment factors of redox sensitive elements. The distribution pattern and controlling factors of redox sensitive elements are then discussed in the paper. Results show that the variations in V and U contents in each transect are in fact very similar. The content variation of Mo is similar to the overall trends of V and U, but more intense than V and U changes. Obviously, the average content of Mo is enriched while V and U depleted in the transects except slightly enriched V in the transect Ⅰ. The contents of V and U in all transects are mainly controlled by the contents of terrigenous debris and biological carbonate as well as the adsorption of fine-grained sediments, whereas the influence of redox environment is low. In contrast, the distribution of Mo mainly depends on the seabed redox environment, but not the contribution of terrigenous debris content and the adsorption of fine-grained sediments. The lower content and enrichment factor of Mo in the Southwestern Sub-basin of the South China Sea may probably attribute to oxidized environment caused by the underflow activity.

     

/

返回文章
返回