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AMT15 pigment composition (HPLC)

Data Acquisition and Analysis

Samples from the five main light depths were collected from 35 casts during the cruise. Samples were taken from niskin bottles fired during the early morning cast and filtered through GF/F filters. The filters were then frozen until the samples were returned to the lab in the UK at the end of the cruise. HPLC analysis was carried out after Barlow et al. (1997).

References Cited

Barlow R.G. , Cummings D.G. and Gibb S.W., 1997. Improved resolution of mono- and divinyl chlorophylls a and b and zeaxanthin and lutein in phytoplankton extracts using reverse phase C8 HPLC. Marine Ecology Progress Series, 161 , 303-307.

Instrumentation Description

Section not relevant.

BODC Data Processing Procedures

Data were submitted to BODC in Microsoft Excel spreadsheet format and archived in accession SOC090128. The file was provided to BODC with cast number, date, sampling position (LAT and LON) and depth as metadata.

Sample metadata were checked against information held in the database - there were three discrepancies. In the data file the LAT figures had the decimal point in the wrong place. Also a number of samples were identified with two cast numbers in the file, these corresponded to stations where two casts were taken to collect water. The samples were matched to the cast where the range of depths provided in the file matched the depths sampled. Finally for cast 41 the range of depths sampled matched the bottle firing depths for cast 42, both these casts were carried out pre-dawn at the same station and so the data were linked to cast 42.

Parameter codes defined in BODC parameter dictionary were assigned to the variables as shown in the table below. Two additional parameters in the file were not loaded to the database: "Fluor Chl" had been supplied to BODC previously and already been loaded, the data were included by the data originator as part of the QC process; "Tot Chl a" was derived as the sum of "Divinyl chl a" and "Chl a" and so was not uploaded to the database. The data were provided in units that were consistent with those used for the relevant parameters in the BODC database, with the exception of "Chl a" where a unit conversion was applied from ng l ^-1 to mg m ^-3 .

Data loaded into BODC's database without any changes.

Data Quality Report

The data originator has carried out a QC analysis of the data by comparing the extracted chl-a fluorometry profiles with the pigment profiles generated from the HPLC analysis. BODC were not advised by the data originator of any suspect data points.

Problem Report

This section is not relevant to this data set.