Mapping and speciation of cadmium in marine sediments: A key to understanding ancient ocean chemistry

The isotopic composition of cadmium in the oceans (δ114/110Cd) has been proposed as a proxy for ancient nutrient utilization, primary productivity and global-scale marine organic carbon burial. The development of this proxy, however, is held back by not having a detailed understanding of how Cd is buried into marine sediments in association with different mineral phases, and how the distribution of Cd is altered during sediment diagenesis and burial. We seek to tackle this issue by quantifying the distribution and speciation of Cd in organic- and sulfur-rich marine sediments for the first time. The results will enable accurate interpretation of sedimentary Cd isotope signatures and ancient ocean chemistry.

海洋中镉的同位素组成（δ114/110Cd）已被提出作为古营养盐利用、初级生产力以及全球尺度海洋有机碳埋藏的地球化学替代指标。然而，由于我们尚未明确镉如何与不同矿物相结合并埋藏于海洋沉积物中，也不清楚沉积物成岩作用与埋藏过程中镉的分布会发生何种改变，该替代指标的发展受到了制约。本研究首次通过定量分析富有机质与富硫海洋沉积物中镉的分布与赋存形态，以期解决这一科学问题。研究成果将为准确解读沉积物镉同位素特征与古海洋化学性质提供可靠依据。