沉积物-水界面交换研究的天然放射性同位素224Ra/228Th新体系

Progresses and Outlooks of the Researche on Solute Exchange Across the Sediment-Water Interface Using A Novel 224Ra/228Th Disequilibrium Approach

本课题组建立了天然放射性同位素新体系——^224Ra/^228Th不平衡法,用于研究沉积物一水界面物质交换。本文详细介绍了该方法的原理和现状,及其在沉积物-水界面溶解物质交换通量与机制、定量评估沉积物与水体间不同尺度传输方式(孔隙水交换和海底地下水排放)等方面的应用;探讨其潜在应用前景,指出近岸和陆架沉积物-水界面铁通量及其对冰期一间冰期大气CO2周期变化的影响、沉积物作为水生环境“二次污染源”风险的定量评估是其潜在应用方向。

We have developed a novel ^224Ra/^228Th disequilibrium approach that is suitable for quantifying benthic solute fluxes from sediments.Here,the principle and the current development of this approach are summarized.We focus the applications of this approach on :(1)constraining benthic solute fluxes from sediments and the associated transport mechanisms;(2)quantifying the relative contribution of benthic inputs with different length scales of transport (i.e.,porewater exchange vs submarine groundwater discharge).We propose that the 224Ra/22STh disequilibrium approach can be applied to at least two fields in the future:(1)to study the benthic flux of dissolved iron (Fe)in marginal sediments and its implication on the glacial-interglacial changes of atmospheric CO2;and (2)to assess the risk of sediments as a secondary source of pollutants in the aquatic environment.