Nutrient concentrations in surface water from time series station L4 in the western English Channel in 2006@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.

普利茅斯海洋实验室（Plymouth Marine Laboratory, PML）西航道观测站长期水文时间序列的L4站位，在条件允许时每周采集硝酸盐、亚硝酸盐、硅酸盐与磷酸盐营养盐样品。样品采用洁净条件采集，随后尽快置于低温避光环境下送回普利茅斯实验室，在该实验室中对三份平行样品分别对经0.2 μm密理博氟罗普（Millipore Fluoropore）滤膜过滤的水样与未过滤水样进行分析。除非存在无法开展现场分析的特殊情况，否则样品不会被储存或冷冻。本次分析采用5通道Bran+Luebbe分段流动分析系统，其使用的分析方法经过充分验证，与PML营养盐研究团队在所有国际科考航次及研究项目中所采用的方法一致。质量控制流程采用标准参考物质开展，该团队同时参与了Quasimeme计划。该操作规范自2007年起沿用至今，在此之前样品会被冷冻储存，随后批量开展分析。