Geochemistry of sediment cores from the continental shelf of the Gulf of Cadiz (North East Atlantic)

Sediment cores were obtained from the continental shelf of the Gulf of Cadiz (North East Atlantic), with water depth ranging from 18 to 32 m. Cores were retrieved in Summer and Autumn 2006 on board of the R/V Mytilus in the framework of the EMIGAS Spanish project ('Zonas de emisión de gases efecto invernadero en los sistemas litorales: influencia de las entradas costeras y del metabolismo bentónico'). Five sampling stations were selected in two different areas: the Bay of Cádiz and its outer region (BOX BC02, BOX BC04, BOX BC05), and the Guadalquivir prodelta (BOX GL03, BOX GL04), which is characterized by a high fluvial supply and a moderate hydrodynamic regime. Major and minor elements (Si, Ti, Al, Fe, Mg, Ca, K, Na, P, S) and trace elements (Mn, V, Cr, Ni, Cu, Zn, Rb, Sr, Y, Zr, Ba, and Pb) show differences in bulk chemical composition between the two areas. Trace metals (V, Cr, Ni, Cu, Zn, and Pb) are found at lower levels in the Bay of Cádiz compared to the Gualdalquivir prodelta. Relatively high concentrations of Zr and Y, commonly associated with the heavy minerals fraction, are found in the top sediment layers of the Bay of Cádiz, and are attributed to the enrichment of heavy minerals related to selective transport.

本研究于东北大西洋加的斯湾（Gulf of Cadiz）大陆架采集沉积物岩芯，采样水深介于18至32米之间。岩芯采集工作于2006年夏、秋季搭载「迈蒂卢斯」号（R/V Mytilus）科研调查船完成，隶属于西班牙EMIGAS项目——该项目全称为《滨海系统温室气体排放区：海岸输入与底栖代谢的影响》（Zonas de emisión de gases efecto invernadero en los sistemas litorales: influencia de las entradas costeras y del metabolismo bentónico）。本次共布设5个采样站位，覆盖两个区域：其一为加的斯湾及其外陆架区域（站位编号BOX BC02、BOX BC04、BOX BC05）；其二为瓜达尔基维尔河三角洲前缘（Guadalquivir prodelta）（站位编号BOX GL03、BOX GL04），该区域以高河流输入量与中等水动力条件为典型特征。常量元素与微量元素（其中常量元素包括Si、Ti、Al、Fe、Mg、Ca、K、Na、P、S，微量元素包括Mn、V、Cr、Ni、Cu、Zn、Rb、Sr、Y、Zr、Ba与Pb）的整体化学组成在两个区域间存在显著差异。痕量金属（V、Cr、Ni、Cu、Zn与Pb）在加的斯湾的含量低于瓜达尔基维尔河三角洲前缘。加的斯湾表层沉积物中Zr与Y的浓度相对较高，这两种元素通常与重矿物组分相关，其富集现象归因于选择性搬运作用驱动的重矿物富集。