Nutrients in porewater of sediment profile 12923-005

Total carbonate (Ct) concentrations were determined on-board ship during Discovery 222 (leg A) nd 226 cruises, using colourmetric methods (Johnsson et al., 1987) with a precision of 0.2% RSD (n=10) using a sample loop of 4ml. During Discovery 231, 236 and Meteor 42/2 cruises a newly developed system (based on infrared detection of (CO2) were used for determination of total carbonate (Goyet and Snover, 1993; OSullivan and Millero, 1998). The precision of this method was also 0.2% RSD (n=10) using a sample loop of 4ml. Samples were filtrated through disposable sterile cellulose acetate filters (0.45µm) and stored refrigerated in polyethylene vials (rinsed in MQ-water) until analysis on-board.

在‘发现者’222（航次A）和226航次期间，船上通过色度法（Johnsson等，1987年）测定了总碳酸盐（Ct）浓度，精度为0.2%的相对标准偏差（n=10），使用4毫升的样品环。在‘发现者’231、236和‘气象’42/2航次中，采用了基于红外检测（CO2）的新开发系统（Goyet和Snover，1993年；OSullivan和Millero，1998年）来测定总碳酸盐。此方法的精度同样为0.2%的相对标准偏差（n=10），使用4毫升的样品环。样品通过可丢弃的灭菌醋酸纤维素滤膜（0.45微米）过滤，并在经过高纯水冲洗的聚乙烯瓶中冷藏保存，直至船上进行分析。