AMT14 underway sampled Particulate Inorganic Carbon (PIC) and Biological Silica (BSi)
Data Acquisition and Analysis
This data originates from analyses on samples collected underway from the ship's non-toxic supply. Water samples were collected every 2 hours during daylight and less frequently over night from the ship's non-toxic supply. PIC was collected from 1 litre of seawater by vacuum filtration onto a 0.45 µm cellulose nitrate filter. The filters were then rinsed with potassium tetraborate buffer and stored in individual cryo vials at room temperature for the remainder of the cruise. BSi was collected from 1 litre of seawater by vacuum filtration onto a 0.4 µm polycarbonate filter, which were then stored in scintillation vials at -20 o C for the duration of the cruise.
PIC: After the cruise the samples were analysed using inductively coupled plasma atomic emission spectrometry (ICPAES).
BSi: After the cruise the residue on the filter paper was dissolved in 2.5 ml sodium hydroxide and then the solution was neutralised with 0.1 mol L -1 hydrochloric acid and the Si concentration was measured using a flow autoanalyser.
References Cited
Instrumentation Description
Not relevant to this dataset.
BODC Data Processing Procedures
Data were submitted to BODC in a tab delimited text format and accessioned under BODC archive BGL060512. Sample metadata were checked against information held in the database - there were a number of discrepancies. Although the sampling times matched those from the underway chl-a samples the lat and lon figures were all marginally different, also on a number of days a sample taken around midnight was logged with the previous days date, this error was apparent from the accompanying lat/lon data. The sample depth supplied in the data was was 5 m, where as the database records for underway chl-a samples gave a depth of 6 m. The data have been corrected to match the BODC database as sampling for chl-a, as sampling was synchronised according to the Cruise Report.
Parameter codes defined in the BODC parameter dictionary were assigned to the variables. The PIC data were converted from mg m -3 to µmol L -1 by dividing by 12. The BSi data were provided in units (mmol m -3 )equivalent to those used in the BODC database for the appropriate parameter code.
A parameter mapping table is provided below;
| Originator's Parameter | Units | Description | BODC Parameter Code | Units | Comments |
|---|---|---|---|---|---|
| PIC | mg m -3 | Concentration of carbon (inorganic) {PIC} per unit volume of the water body [particulate >0.4µm phase] by filtration, acid digestion and inductively-coupled plasma atomic emission spectroscopy | CINGFA04 | µmol l -1 | Unit conversion of x1/12 applied to data |
| BSi | mmol m -3 | Concentration of biogenic silica {opal} per unit volume of the water body [particulate >0.4um phase] by filtration, alkali hydrolysis and colorimetric analysis | OPALWCP4 | µmol l -1 | n/a |
Data Quality Report
BODC were not advised of specific quality checks carried out by the data originator.
Problem Report
Not relevant to this dataset.
