AMT12 Particulate Organic Carbon (POC) and Particulate Organic Nitrogn (PON) concentrations from CTD bottle samples
Originator's Protocol for Data Acquisition and Analysis
This data originates from analyses on samples collected from 14 CTD casts during the cruise. Water samples were collected from the five main light depths during the pre-dawn CTD cast using the Sea-Bird CTD rosette system. Samples were filtered on GF/F filters and stored for analysis back at SOC, now National Oceanography Centre Southampton (NOC) with later cruises.
POC and PON were measured after inorganic carbonates were removed from the filters by acidification with fuming concentrated hydrochloric acid. The filters were dried in a 60 o C oven for 24 hrs, packaged in pre-combusted aluminium foil (Hilton et al. , 1986) and analysed on a Thermo Finnegan flash EA1112 elemental analyser (Poulton et al. , 2007).
References Cited
Hilton J., Lishman J.P., Mackness S. and Heaney S.I., 1986. An automated method for the analysis of particulate carbon and nitrogen in natural waters. Hydrobiologia, 141, 269-271.
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
Thermo Finnegan flash EA1112 elemental analyser
BODC Data Processing Procedures
Data were submitted via email in an Excel spreadsheet archived under BODC's accession number SOC050004. Sample metadata (Cruise, CTD cast, latitude, longitude, light depth and depth) were checked against information held in the database. There were no discrepancies.
Parameter codes defined in BODC parameter dictionary were assigned to the variables. The data were provided in mg m -3 and these were converted to match the parameter units in the BODC database. The conversion involved dividing mg m -3 by the atomic mass (C=12, N=14 respectively) to generate mmol m -3 (equivalent to µmol L -1 ).
The data were reformatted and loaded in BODC's samples database under Oracle Relational Database Management System. Data were marked up with BODC parameter codes and loaded into the database. Individual samples were matched through rosette sampling bottle and depth.
A parameter mapping table is provided below;
| Originator's Parameter | Units | Description | BODC Parameter Code | Units | Comments |
|---|---|---|---|---|---|
| POC | mg m -3 | Concentration of carbon (organic) {POC} per unit volume of the water body [particulate >GF/F phase] by filtration, acidification and elemental analysis | CORGCAP1 | µmol l -1 | n/a |
| PON | mg m -3 | Concentration of nitrogen (total) {'PON'} per unit volume of the water body [particulate >GF/F phase] by filtration, acidification and elemental analysis | NTOTCAP1 | µmol l -1 | n/a |
Data Quality Report
BODC were not advised of specific quality checks carried out by the data originator since. There were no standout values in the sample data provided to BODC.
Problem Report
Not relevant to this data set.
