A highly sensitive and detailed vertical distribution of nutrients in surface oceanic waters as a basis for evaluation of carbon dioxide absorption flux

将连续流动分析系统与长程毛细管流动池(LWCC)相结合，建立了一种高灵敏度的海水营养盐比色分析方法。在2米光路池中，海水中磷酸盐的检出限为2.8 nm。对硅酸盐和砷酸盐的干扰进行了检查，发现除非添加砷酸盐的还原剂，否则砷酸盐的影响很大。在R/V Umitaka-Maru和R/V Shinyo-Maru的几次巡航中，确定了表层或真光层中营养物质的详细垂直分布。对于分层和贫营养水体，高灵敏比色法被应用于磷酸盐的分析。用高灵敏的化学发光法分析硝酸盐(+亚硝酸盐)。在2003年1月至2月的Umitaka-Maru邮轮期间，通过常规比色分析获得了南大洋营养物质的详细概况。在这些观测中，发现混合层中磷酸盐的营养浓度开始增加的深度(或营养线顶部的深度)比硝酸盐的浅。这些特征可能反映了浅海水域氮磷动态变化的一般规律。这些营养素的高灵敏比色分析可用于高灵敏的营养素表面监测和星载培养实验。

A highly sensitive method was developed for colorimetric analysis of nutrients in seawater by combining a continuous flow analysis system and a long path-length capillary flow cell (LWCC). With a 2-m light path cell, the detection limit of phosphate in seawater was 2.8nM. Interference with silicate and arsenate was examined and arsenate was to found to affect significantly unless a reduction reagent for arsenate was added. During several cruises of R/V Umitaka-maru and R/V Shinyo-maru, detailed vertical distributions of nutrients within surface or euphotic layers were determined. For stratified and oligotrophic waters, the highly sensitive colorimetric method was applied in phospate analysis. Nitrate (+nitrite) was analyzed by a highly sensitive chemiluminescence method. Detailed profiles of nutrients were obtained by conventional colorimetric analysis in the Southern Ocean during a Umitaka-maru cruise in January-February 2003. In these observations, the depth at which nutrient concentration begins to increase (or the depth of top of the nutricline) was found to be shallower for phosphate than for nitrate within the mixed layer. These features may reflect the general pattern of difference between nitrogen and phosphate dynamics in shallow oceanic waters. The highly sensitive colorimetric analysis of these nutrients can be used in high sensitive surface monitoring of nutrients and onboard incubation experiments.