Nutrient concentrations in surface water from time series station L4 in the western English Channel in 2001@en

Nutrient samples for nitrate, nitrite, silicate and phosphate are taken weekly, when possible, at station L4 of the Plymouth Marine Laboratory Western Channel Observatory long-term hydrographic time series. They are sampled under clean conditions and returned in the cool and dark, and as soon as possible, to the laboratory in Plymouth where triplicate samples are analysed both for filtered (0.2 µm Millipore Fluoropore) and non-filtered water. Samples are not stored or frozen unless there are extenuating circumstances making the live analysis impossible. The analyser is a 5-channel Bran and Luebbe segmented flow system using well tested methodologies, and the same as those used by the PML nutrient group in all their International Research cruises, and research programmes. Quality control procedures are carried out using certified reference materials, and also the group participates in the Quasimeme programme. This has been the protocol since 2007, and prior to that the samples were stored frozen and then analysed in batches.在普利茅斯海洋实验室（Plymouth Marine Laboratory, PML）西部航道观测站的长期水文时间序列L4站位，条件允许时每周采集硝酸盐、亚硝酸盐、硅酸盐与磷酸盐的营养盐样品。样品在洁净条件下采集后，尽快置于阴凉避光环境中送回普利茅斯实验室；在该实验室中，对三份平行样品分别开展经0.2 µm 密理博氟孔膜（Millipore Fluoropore）过滤的水样与未过滤水样的分析。除非存在无法开展现场分析的特殊情况，否则样品不予储存或冷冻。本次分析采用5通道布兰吕贝（Bran and Luebbe）分段流动分析系统，所用方法经过充分验证，与普利茅斯海洋实验室营养盐研究团队在所有国际科研航次及科研项目中使用的方法一致。质量控制流程通过标准参考物质实施，该团队同时参与Quasimeme项目。该实验规程自2007年起沿用至今，在此之前样品均采用冷冻储存后分批分析的处理方式。