Carbonate and Aluminium accumulation in the central equatorial Pacific Ocean

We examined the flux of Al to sediment accumulating beneath the zone of elevated productivity in the central equatorial Pacific Ocean, along a surface sediment transect at 135°W as well as downcore for a 650 kyr record at 1.3°N, 133.6°W. Across the surface transect, a pronounced, broadly equatorially symmetric increase in Al accumulation is observed, relative to Ti, with Al/Ti ratios reaching values 3-4 times that of potential detrital sources. The profile parallels biogenic accumulation and the modeled flux of particulate 234Th, suggesting rapid and preferential adsorptive removal of Al from seawater by settling biogenic particles. Normative calculations confirm that most Al is unsupported by the terrigenous fraction. […]

本研究探讨了在中央赤道太平洋地区生产力增强带下方沉积物中积累的铝（Al）通量，在135°W的海面沉积物横截面上进行了观察，并在1.3°N，133.6°W处通过岩芯分析获取了长达650千年的记录。在横截面上，相较于钛（Ti），铝的积累表现出显著且广泛地呈赤道对称性的增加，铝钛比（Al/Ti）达到了潜在碎屑源3至4倍的水平。该剖面与生物成因积累及模型模拟的颗粒234Th通量相吻合，表明海水中铝通过沉降生物颗粒的优先吸附去除作用迅速减少。规范计算证实，大部分铝的积累并不依赖于陆源物质。