An Investigation of the Mechanism(s) of Barite Formation in Seawater

重晶石是一种极难溶解的结晶形式的硫酸钡，在世界各地的海水中都有发现，这是现代化学海洋学的谜团之一。虽然微晶通常具有直接从溶液中析出的晶体的外观，但由于Ba2+的浓度太低，不能提供从饱和到过饱和的溶液化学来引起直接沉淀。在这项研究中，伍兹霍尔海洋研究所的地球化学家将通过研究几种最有希望的重晶石形成机制来解决这个问题。他们认为，最可能的机制是在下沉、分解生物颗粒周围的微环境中产生过饱和条件，但也将考虑其他可能性(如蛋白石表面的催化作用和天青石的溶解，富含钡的矿物)。由于重晶石在海洋沉积物中保存相对较好，其积累速度可能会提供过去海洋出口生产力变化的定量信息(浮游植物固定二氧化碳并将其输送到深处的能力的衡量标准)。

ABSTRACTOCE-9819103The fact that the mineral barite, a very insoluble and crystalline form of barium sulfate, is found in marine waters around the world is one of the mysteries of modern chemical oceanography. Although the microcrystals usually have the appearance of crystals precipitated directly from solution, the concentration of barium is too low to provide the saturated-to-supersaturated solution chemistry to cause direct precipitation. In this study, geochemists from the Woods Hole Oceanographic Institution will tackle this problem by studying several of the most promising candidate mechanisms for barite formation. They believe that the most likely mechanism would involved the generation of supersaturated conditions in the microenvironment around sinking, decomposing biogenic particle, but other possibilities (such as catalytic effects of opal surfaces and dissolution of celestite, abarium-rich mineral) will also be considered. Because barite is relatively well preserved in marine sediments, its rate of accumulation could potentially provide quantitative information on past changes in oceanic export productivity (a measure of the ability of the ability of the phytoplankton to fix carbon dioxide and deliver it to depth).