Interstitial-water chemistry of ODP Leg 119 sites

Ocean Drilling Program inorganic geochemistry procedures routinely overlook more than 99% of the sediment column. Present and past biogeochemical reactions alter the sediment record; however, most of these reaction zones are bypassed by the normal methods where samples are collected every 30 m. A new approach to increase resolution was introduced during Leg 119. Ten milliliters of sediment provided interstitial-water samples for ammonia, silica, sulfate, magnesium, and calcium analyses. The new method introduced some systematic differences in concentrations, as well as some decrease in precision. A number of advantages, however, may warrant using the method in some instances. In cases where routine interstitial-water data showed anomalous results, core sections were retrieved from the storage facility and resampled. The new high-resolution procedure was used to provide water samples in cases were water contents were low and routine squeezing could not recover pore water.大洋钻探计划（Ocean Drilling Program）的常规无机地球化学分析流程通常会遗漏超过99%的沉积物柱体。现今与历史时期的生物地球化学反应均会改变沉积物记录，但常规采样间隔为30米的分析方法会绕过绝大多数此类反应发生区域。第119航次（Leg 119）首次引入了一种提升采样分辨率的新方法：仅需10毫升沉积物即可提取孔隙水（interstitial water）样品，用于氨、二氧化硅、硫酸盐、镁及钙的含量分析。该新方法会引入部分浓度系统性偏差，同时也会导致分析精度一定程度下降，但该方法具备多项优势，因此在部分场景下仍值得采用。当常规间隙水分析数据出现异常结果时，研究人员会从存储设施中取出岩心段并进行重新采样；当沉积物含水率过低、常规挤压法无法提取孔隙水时，也会采用这种新型高分辨率流程来获取水样。