AMT15 CTD rosette sampled Particulate Inorganic Carbon (PIC) and Biological Silica (BSi)
Data Acquisition and Analysis
This data originates from analyses on samples collected from CTD casts during the AMT15 cruise. Samples were taken from 6 main light depths from the pre-dawn CTD cast (~0200 - 0400h local time) and from the late morning 'optics' cast (1100h local time). 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
Poulton A.J., Adey T.R., Balch W.M., and Holligan P., 2007. Relating coccolithophore calcification rates to phytoplankton community dynamics: regional differences and implications for carbon export. Deep-Sea Research Part II, 54(5-7), 538-557.
Instrumentation Description
Not relevant to this dataset.
BODC Data Processing Procedures
Data were submitted to BODC in a tab delimited text format and accession under BODC archive BGL060512. Sample metadata were checked against information held in the database. There were 3 discrepancies in the metadata provided. Casts 94 and 104 had been incorrectly labelled as duplicate 91 and 101 casts with the lat, lon and date used to identify the correct casts and cast 76 was actually cast 77 based on the lat/lon/time of sampling and bottle firing depths. The correct station/cast was assigned to each cast.
Parameter codes defined in the BODC parameter dictionary were assigned to the variables. The data for PIC were converted from mg m -3 to µmol L -1 , this was achieved by dividing by 12 (atomic mass of carbon) and the BSi data were provided in units (mmol m -3 ), which were consistent with those used in the BODC database for the parameter codes (µmol L -1 ).
Data loaded into BODC's database with only a unit conversion change applied.
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 >0.4µm 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 originators. There were no standout values in the sample data provided to BODC.
Problem Report
Not relevant to this dataset.