AMT11 extracted size-fractionated chlorophyll-a measured fluormetrically from CTD bottle samples
Data Acquisition and Analysis
This data originates from analyses on samples collected from CTD rosette bottles for 45 CTD casts. Water-column sampling for size-fractionated chl-a measurements during AMT11 concentrated around collection of the main core measurements from 5 or 6 light depths from the predawn CTD cast (~0200 - 0400h local time), with a reduced set of measurements and depths from the late morning 'optics' cast (1100h local time). The measurements were made for comparison with the depths sampled for the Primary Production ( 14 C) incubations carried out during the cruise.
Water samples from the 5-6 main light depths were collected from CTD bottles. 300 ml samples were filtered sequentially through 0.2, 2 and 20 µm polycarbonate filters which were immediately placed in glass vials and 8 ml of 90% added. After extraction at -20 °C for ca. 20 hours, chlorophyll a fluorescence was measured with a Turner Designs 10-AU fluorometer.
References Cited
Instrumentation Description
Not relevant to this dataset.
BODC Data Processing Procedures
Data were submitted to BODC in an Excel spreadsheet on two occasions first with the Primary Production incubation data and later as a dataset in its own right. These files were accessioned under BODC archive UVI020056 and PML030067 respectively. The data were compared and the only difference was number of decimal places the data were provided in (2dp and 3dp respectively). The data provided with the Primary Production data were loaded to the database. Sample metadata provided (CTD cast, latitude 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 variable. The units supplied in the spreadsheet were mg m -3 , which match the Parameter Dictionary units so no unit conversions were necessary.
Data loaded into BODC's database without any changes applied.
A parameter mapping table is provided below;
Originator's Parameter | Units | Description | BODC Parameter Code | Units | Comments |
---|---|---|---|---|---|
Chl 0.2-2 µm | mg m -3 | Concentration of chlorophyll-a {chl-a} per unit volume of the water body [particulate 0.2-2µm phase] by filtration, acetone extraction and fluorometry | SCHLFLPF | mg m -3 | n/a |
Chl>2 µm | mg m -3 | Concentration of chlorophyll-a {chl-a} per unit volume of the water body [particulate >2µm phase] by filtration, acetone extraction and fluorometry | SCHLFLPB | mg m -3 | n/a |
Chl 2-20 µm | mg m -3 | Concentration of chlorophyll-a {chl-a} per unit volume of the water body [particulate 0.2-2µm phase] by filtration, acetone extraction and fluorometry | SCHLFLPG | mg m -3 | n/a |
Chl>20 µm | mg m -3 | Concentration of chlorophyll-a {chl-a} per unit volume of the water body [particulate >20µm phase] by filtration, acetone extraction and fluorometry | SCHLFLPQ | mg m -3 | n/a |
Chlorophyll-a | mg m -3 | Concentration of chlorophyll-a {chl-a} per unit volume of the water body [particulate >0.2µm phase] by filtration, acetone extraction, fluorometry and summation of size-fractionated values | CPHLFLP4 | mg m -3 | n/a |
Data Quality Report
BODC were not advised of any data quality checks made by the data originator prior to submission of the dataset.
Problem Report
Not relevant to this dataset.