AMT6 POC/PON measurements from CTD bottle samples
Originator's Protocol for Data Acquisition and Analysis
This data originates from analyses of water samples collected from 38 CTD casts.
At each morning station, samples of particulates for CHN analyses were obtained from CTD water bottles at two different depths: surface (7m) and chlorophyll maximum, as determined by in situ fluorescence. Water samples from the two depths were filtered through 5 µm membrane filter, and a 200 µm gauze. The filtrate from each size fraction was filtered into triplicate onto pre-ashed Whatman GF/F filters to produce a series of replicate samples of the two size fractions (< 5 and < 200 µm). Filters were dried for 24 hours in the oven (60 o C) and then compacted in pre-ashed aluminium foil and frozen for subsequent CHN analysis.
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 to the BODC archive with reference PML020111. The data were provided with Date, time, latitude and depth. Sample metadata were checked against information held in the database - there were two discrepancies. Two samples could not be matched to CTDs; one sample was labelled as being from non-toxic, so the other odd sample was assumed also to be a non-toxic supply sample.
There was no supporting eveidence to suggest the filters were acidified during analysis and therefore the data is believed to relate to total rather than organic particulate carbon. Carbon and Nitrogen data were converted from mg m -3 to µmol l -1 by dividing by 12.0107 and 14.0067 respectively.
Parameter codes defined in BODC parameter dictionary were assigned to the variables. The data were assigned parameter codes defined in BODC parameter dictionary. Data 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 |
|---|---|---|---|---|---|
| Mean Carbon (< 200 µm) | mg m -3 | Concentration of carbon (total) {'POC'} per unit volume of the water body [particulate GF/F-200um phase] by filtration, no acidification and elemental analysis | SCRGCNPJ | µmol l -1 | - |
| Mean Carbon (< 5 µm) | mg m -3 | Concentration of carbon (total) {'POC'} per unit volume of the water body [particulate GF/F-5um phase] by filtration, no acidification and elemental analysis | SCRGCNPM | µmol l -1 | - |
| Mean Nitrogen (< 200 µm) | mg m -3 | Concentration of nitrogen (total) {'PON'} per unit volume of the water body [particulate GF/F-200um phase] by filtration and elemental analysis | SFNTCNPJ | µmol l -1 | - |
| Mean Nitrogen (< 5 µm) | mg m -3 | Concentration of nitrogen (total) {'PON'} per unit volume of the water body [particulate GF/F-5um phase] by filtration and elemental analysis | SFNTCNPM | µmol l -1 | - |
Data Quality Report
BODC has not been advised of any quality checks carried out by the data originator.
Problem Report
Not relevant to this data set.
