AMT2 Nutrient (micromolar) measurements from underway surface samples
Originator's Protocol for Data Acquisition and Analysis
This data originates from analyses of samples taken from the ship's non-toxic supply on 158 occasions during the cruise.
Concentrations of dissolved nitrate, nitrite, phosphate and silicate were measured using a 4-channel Technicon autoanalyser. Underway samples, taken from the ship's non-toxic supply at approximately 4 hourly intervals were analysed. All 4 nutrients being successfully determined in 99.4% of the underway samples.
On the whole, the system was stable and reliable from day to day. There were some initial problems with bubble patterns at the beginning of the cruise due, in part, to the severity of the weather on leaving Port Stanley. Lubrication of the autoanalyser pumps rectified the majority of the hydraulic problems, indicating that the pump oil had dried out between AMT-1 and AMT-2 and that lubrication of the pumps and rollers should become standard procedure prior to commencing analysis on subsequent cruises. Problems with the nitrite channel persisted for a further 3 days before a constricted return line was identified. Following its replacement, no further problems were encountered.
References Cited
Instrumentation Description
Not relevant to this data set.
BODC Data Processing Procedures
Data were submitted to BODC in Microsoft Excel spreadsheet format and saved in the BODC archive with reference PML980063. Sample metadata were checked against information held in the cruise report - there was one discrepancy with what appeared to be a typing error in the Julian Day data in the originator's file. The Julian Day was given as 136 with time 12:00 but was positioned in between other JD 126 data in the original file. Also the data was the same before and after for the samples analysed during JD 126 but results in a spike on all four parameters when placed at JD 136. The data has been loaded against a sample collected at 12:15 on JD126. There were no nitrite data for 4 samples indicated by N/A in originator's file. The data were assigned parameter codes defined in BODC parameter dictionary. Data were loaded into BODC's database using established BODC data banking procedures.
A parameter mapping table is provided below;
| Originator's Parameter | Units | Description | BODC Parameter Code | Units | Comments |
|---|---|---|---|---|---|
| Nitrate+Nitrite | µmol l -1 | Concentration of nitrate+nitrite {NO 3 +NO 2 } per unit volume of the water body [dissolved plus reactive particulate <unknown phase] by filtration and colorimetric autoanalysis | NTRZAADZ | µmol l -1 | - |
| Nitrite | µmol l -1 | Concentration of nitrite {NO 2 } per unit volume of the water body [dissolved plus reactive particulate <unknown phase] by filtration and colorimetric autoanalysis | NTRIAADZ | µmol l -1 | - |
| Phosphate | µmol l -1 | Concentration of phosphate {PO 4 } per unit volume of the water body [dissolved plus reactive particulate <unknown phase] by filtration and colorimetric autoanalysis | PHOSAADZ | µmol l -1 | - |
| Silicate | µmol l -1 | Concentration of silicate {SiO 4 } per unit volume of the water body [dissolved plus reactive particulate <unknown phase] by filtration and colorimetric autoanalysis | SLCAAADZ | µmol l -1 | - |
Data Quality Report
BODC has not been advised of any data quality checks carried out by the data originator. A number of negative data values have been flagged suspect with BODC flag 'M'.
Problem Report
Not relevant to this data set.
