L4 surface nutrients data

The nutrient samples for L4 are taken weekly where conditions allow. They are sampled under clean conditions and returned as soon as possible in the cool and dark to the laboratory in Plymouth where triplicate samples are analysed for filtered (0.2µm Millipore Fluoropore) water. This gives us essentially 'live' results which are processed and uploaded as soon as possible after analysis. Samples are not frozen unless there are extenuating circumstances making the live analysis impossible. The analyser is a 5-channel SEAL segmented flow system using well tested methodologies; the same as those used by the PML nutrient group in all their International Research cruises, and research programmes. As the samples are taken and stored for sometimes 2-3 hours before returning for analysis, and sometimes frozen, the concentrations for Ammonium should be treated with care due to it being subject to storage and contamination problems. The Ammonium data should be viewed more as trends rather than highly accurate concentrations. Quality control procedures are carried out using KANSO certified reference materials, the group also participates in the Quasimeme programme. This has been the protocol since 2007, prior to that, the samples were stored frozen and analysed in batches. The L4 data record contains the surface values presented in graphical format here; depth profiles of nutrients at L4 are available since February 2012. To use these data please contact Malcolm Woodward (m.woodward@pml.ac.uk). Click here to download the data.

Nitrate

Nitrite

Phosphate

Silicate