Dataset: Chlorophyll-a concentrations in seawater near the BATS station, cruises AE2113 and AE2303

Name: Chlorophyll-a concentrations in seawater collected near the BATS station during R/V Atlantic Explorer cruises AE2113 (July 2021) and AE2303 (January 2023)
Published: 2024-06-20
Keywords: BATS, Major Ions, aerosols, oceans

Cite This Dataset

DOI:10.26008/1912/bco-dmo.929873.1

Spatial Extent: N:31.69 E:-64.156 S:31.652 W:-64.202

Bermuda Atlantic TimeSeries Study (BATS) station

Temporal Extent: 2021-07-23 - 2023-01-28

Project:

Collaborative Research: Seasonal Variability in refractory dissolved organic carbon fluxes associated with primary marine aerosol emitted from the oceans (Carbon Flux and Aerosol Emissions)

Program:

United States Surface Ocean Lower Atmosphere Study (U.S. SOLAS)

Ocean Carbon and Biogeochemistry (OCB)

Principal Investigator:

David J. Kieber (State University of New York College of Environmental Science and Forestry, SUNY ESF)

Scientist:

Lei Xue (State University of New York College of Environmental Science and Forestry, SUNY ESF)

BCO-DMO Data Manager:

Dana Stuart Gerlach (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Audrey Mickle (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Version:

Version Date:

2024-06-20

Restricted:

Validated:

Yes

Current State:

Final no updates expected

Chlorophyll-a concentrations in seawater collected near the BATS station during R/V Atlantic Explorer cruises AE2113 (July 2021) and AE2303 (January 2023)

Abstract:

This dataset includes the concentrations of Chlorophyll a (Chl a) determined in 0.2 µm-filtered seawater samples collected from the Bermuda Atlantic Time-series Study (BATS) station during a summer cruise in 2021 and a winter cruise in 2023. The Chl a concentration in each sample was quantified by fluorescence under subdued lighting using a Turner Designs model AU-10 fluorometer by Dr. Joanna Kinsey. This dataset was compiled by Dr. Lei Xue under the supervision of Dr. David Kieber at the State University of New York, College of Environmental Science and Forestry. These data were used to evaluate the seasonal variation of primary productivity at the BATS station. This work is part of a larger study to understand the seasonal variability in the fraction of refractory organic carbon in primary marine aerosol at the BATS station.

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Archival Copy

Version Date	Archive	Persistent Identifier (PID)	Date PID Issued
2024-06-20	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.26008/1912/bco-dmo.929873.1	2024-08-01

Methods & Sampling

Seawater samples were collected using Niskin bottles from CTD casts taken at the Bermuda Atlantic Time-series Study (BATS) station aboard the R/V Atlantic Explorer during a summer cruise in 2021 (AE2113) and a winter cruise in 2023 (AE2303). Seawater samples were collected in pre-cleaned opaque brown polyethylene bottles and then analyzed for chlorophyll a (Chl-a) following extraction into 90% acetone:10% high purity water according to the method outlined in Welschmeyer, 1994. Briefly, after a seawater sample was collected from the CTD rosette, a known volume of that seawater was filtered through a 25 mm diameter GF/F glass fiber filter under subdued lighting and at ~100 mm Hg pressure differential. Samples were filtered within 30 min of sample collection. The filter-funnel walls were then rinsed with previously filtered seawater. The filter was folded with a flat-tipped forcep and placed in a borosilicate test tube that was tightly capped. The test tube was wrapped in Al foil and frozen. Once several samples were processed and stored this way, they were removed from the freezer and 4 mL of 90% (v/v) acetone (Burdick and Jackson, spectrophotometric grade) diluted with high-purity laboratory water (Milli-Q water from a Barnstead water system) was added. The samples were vigorously shaken, wrapped in Al foil, and returned to the freezer without letting the samples return to room temperature. The Chl-a extracted overnight in the freezer (ca. 12 hr) in the dark. Chl-a in the acetone extracts was quantified by fluorescence under subdued lighting using a Turner Designs model AU-10 fluorometer. Samples were removed from the freezer and warmed to room temperature in the dark prior to analysis.

Data Processing Description

Chlorophyll a Concentration Calculation: To obtain chlorophyll-a concentrations, blank-corrected fluorescence values obtained from the AU-10 fluorometer were converted to micrograms of Chl-a per liter (ug/L Chl-a) by using the standard curve equation obtained from calibration with an authentic Chl-a standard diluted in 90% acetone prior to the cruise. Secondary solid standards were analyzed daily during the cruise to ensure that the calibration of the AU-10 fluorometer remained constant. Concentrations were corrected based on the filtered and extract volumes, as well as dilution factors, when needed.

AU-10 fluorometer calibrations were completed by the Bermuda Institute of Ocean Sciences (BIOS) staff. For AE2113 a slope of 0.00041236 was used with an acid ratio of 1.859. For AE2303 a slope of 0.0032515 was used with an acid ratio of 1.80671.

BCO-DMO Processing

- Imported data from two source files into the BCO-DMO data system. Concatenated files “AE2303_Chl a data.xlsx" and “AE2113_Chl a data.xlsx" to create a single data table.
- Combined date and time columns and converted to ISO8601 date format – from m.d.yyyy hh:mm to yyyy-mm-dd hh:mm
- Added column for cruise ID
- Converted latitude and longitude values to decimal degrees (where south and west directions are negative)
- Renamed fields to comply with BCO-DMO naming conventions
- Removed local time field

Data Files

File
929873_v1_chl_a.csv (Comma Separated Values (.csv), 5.52 KB) MD5:1134254cdbfde145e43842739755ff70 Primary data file for dataset ID 929873, version 1

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-2023104

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
AE2113		2021-07-22	R/V Atlantic Explorer	Steven R. Beaupré (Chief Scientist)	data info
AE2303		2023-01-18	R/V Atlantic Explorer	Steven R. Beaupré (Chief Scientist)	data info

Instruments

CTD Sea-Bird SBE 911plus

Supplied Name: CTD rosette equipped with Sea-Bird Electronic sensors

Supplied Description:

Seawater samples were collected from casts using CTD Sea-Bird SBE 911+.

Instrument Type

Generic Name: CTD Sea-Bird SBE 911plus

Acronym: CTD SBE 911plus

Community Identifier: http://vocab.nerc.ac.uk/collection/L22/current/TOOL0058/

Generic Description:

The Sea-Bird SBE 911 plus is a type of CTD instrument package for continuous measurement of conductivity, temperature and pressure. The SBE 911 plus includes the SBE 9plus Underwater Unit and the SBE 11plus Deck Unit (for real-time readout using conductive wire) for deployment from a vessel. The combination of the SBE 9 plus and SBE 11 plus is called a SBE 911 plus. The SBE 9 plus uses Sea-Bird's standard modular temperature and conductivity sensors (SBE 3 plus and SBE 4). The SBE 9 plus CTD can be configured with up to eight auxiliary sensors to measure other parameters including dissolved oxygen, pH, turbidity, fluorescence, light (PAR), light transmission, etc.). more information from Sea-Bird Electronics

Niskin bottle

Supplied Name: 30 L Niskin bottles

Supplied Description:

Seawater samples were obtained using 30 L Niskin bottles attached to a CTD rosette.

Instrument Type

Generic Name: Niskin bottle

Community Identifier: http://vocab.nerc.ac.uk/collection/L22/current/TOOL0412/

Generic Description:

A Niskin bottle (a next generation water sampler based on the Nansen bottle) is a cylindrical, non-metallic water collection device with stoppers at both ends. The bottles can be attached individually on a hydrowire or deployed in 12, 24, or 36 bottle Rosette systems mounted on a frame and combined with a CTD. Niskin bottles are used to collect discrete water samples for a range of measurements including pigments, nutrients, plankton, etc.

Turner Designs Fluorometer 10-AU

Supplied Name: Turner Designs model AU-10 fluorometer

Supplied Description:

The Turner Designs 10-AU Field Fluorometer was used to measure Chlorophyll fluorescence. The 10AU Fluorometer can be set up for continuous-flow monitoring or discrete sample analyses. A variety of compounds can be measured using application-specific optical filters available from the manufacturer.

Instrument Type

Generic Name: Turner Designs Fluorometer 10-AU

Acronym: Turner Fluorometer 10-AU

Community Identifier: http://vocab.nerc.ac.uk/collection/L22/current/TOOL0393/

Generic Description:

The Turner Designs 10-AU Field Fluorometer is used to measure Chlorophyll fluorescence. The 10AU Fluorometer can be set up for continuous-flow monitoring or discrete sample analyses. A variety of compounds can be measured using application-specific optical filters available from the manufacturer. (read more from Turner Designs, turnerdesigns.com, Sunnyvale, CA, USA)

Parameters

Date and time formats are described in python strftime() syntax.

Supplied Name	Supplied description	Supplied Units	Standard Name
Cruise_ID	Cruise ID	unitless	cruise_id
Sampling_ISO_Datetime_UTC	Date and time of CTD sample collected Format: %Y-%m-%dT%H:%MZ	unitless	ISO_DateTime_UTC
CTD_Filename	File of CTD deployment	unitless	file_name
Latitude	Latitude of sample collection	decimal degrees	lat
Longitude	Longitude of sample collection	decimal degrees	lon
Station	Sampling station	unitless	station
Cast	CTD cast number	unitless	cast
CTD_Bottle	Number of Niskin bottle from the CTD cast	unitless	bot_Nis
Salinity	Salinity from CTD Sensor	part per thousand (ppt)	sal_ctd
Temperature	Temperature of water from CTD Sensor	degree Celsius	temp
Sampling_Depth	Depth below surface from CTD Sensor	meter (m)	depth
Volume_Filtered	Sample volume filtered for Chl a measurement	milliliter (ml)	vol_filt
Dilution_Factor	The magnitude of dilution made for filtered sample	unitless	dilution
Extraction_Volume	Volume of acetone used for Chl a extraction	milliliter (ml)	volume
Chl_a	Concentration of Chlorophyll a	microgram per liter (ug/L)	chl_a