Dataset: EN589 Seawater Chlorophyll

Name: Seawater chlorophyll-a from R/V Endeavor cruise EN589 in the Northwest Atlantic Ocean from September to October 2016 (Refractory DOC Recycling project)
Published: 2019-01-02
Keywords: oceans

Cite This Dataset

Spatial Extent: N:41.41893 E:-63.28855 S:34.99955 W:-70.83515

Temporal Extent: 2016-09-16 - 2016-10-15

Project:

Collaborative Research: Coupled Ocean-Atmosphere Recycling of Refractory Dissolved Organic Carbon in Seawater (Refractory DOC Recycling)

Program:

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

Principal Investigator:

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

BCO-DMO Data Manager:

Mathew Biddle (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Version:

Version Date:

2019-01-02

Restricted:

Validated:

Current State:

Preliminary and in progress

Seawater chlorophyll-a from R/V Endeavor cruise EN589 in the Northwest Atlantic Ocean from September to October 2016 (Refractory DOC Recycling project)

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Description

Seawater samples collected from CTD casts and analyzed for Chl a.

Methods & Sampling

Chlorophyll a Methods: Seawater samples were collected from CTD casts in pre-cleaned opaque brown polyethylene bottles and then analyzed from chlorophyll a (Chl-a) after 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, 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 then 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. The samples were vigorously shaken, wrapped in Al foil, and 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.

Chlorophyll a Concentration Calculation: To obtain chlorophyll a concentrations, blank-corrected fluorescence values obtained from the AU-10 were converted to ug Chl- a/L 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 remained constant. Concentrations were corrected based on the filtered and extract volumes, as well as dilution factors, when needed.

Relevant Reference:

Welschmeyer, N.A. 1994. Fluorometric analysis of chlorophyll a in the presence of chlorophyll b and pheopigments. Limnol. Oceanogr. 39: 1985-1992. 10.4319/lo.1994.39.8.1985

Data Processing Description

BCO-DMO Processing:
Added conventional header with dataset name, PI name, version date.
Modified parameter names to conform with BCO-DMO naming conventions.
Re-formatted date from dd-MM-YY to yyyymmdd.
Re-formatted the latitude longitude pairs from degrees decimal minutes to decimal degrees.

2019-01-02: revised the station positions and changed cast ID 16267U1804 to 16267U1604. Version 2 (2019-01-02) replaces version 1 (2017-07-19).

Data Files

File
EN589_chla_v20190102.csv (Comma Separated Values (.csv), 9.29 KB) MD5:dcf5ad628a6a4efb1c779008b763442c Primary data file for dataset ID 710245

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-1536605
NSF Division of Ocean Sciences	OCE-1536674
NSF Division of Ocean Sciences	OCE-1536597
NSF Division of Ocean Sciences	OCE-1536608

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
EN589		2016-09-16	R/V Endeavor	David J. Kieber (Chief Scientist)	data info

Instruments

Niskin bottle

Supplied Name: Seawater samples were collected from CTD casts.

Supplied Description:

Seawater samples were collected from CTD casts in pre-cleaned opaque brown polyethylene bottles and then analyzed from chlorophyll a (Chl-a) after extraction into 90% acetone:10% high purity water according to the method outlined in Welschmeyer, 1994.

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:

Chl-a in the acetone extracts was quantified by fluorescence under subdued lighting using a Turner Designs model AU-10 fluorometer.

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
Sample_Date	Date when the sample was collected.	yyyymmdd	date
Latitude	Latitude coordinate where the sample was collected, South is negative.	decimal degrees	lat
Longitude	Longitude coordinate where the sample was collected, West is negative.	decimal degrees	lon
Cast_ID	Identifier for the specific cast which collected the data.	unitless	cast
CTD_Sample_Depth	Depth at which the sample was collected.	meters (m)	depth
Vol_Filtered	Total amount of water filtered.	mililiters (mL)	vol_filt
Vol_Extracted	Total amount extracted after filtering.	mililiters (mL)	no_bcodmo_term
Dilution_Factor	Factor by which the sample was diluted	unitless	no_bcodmo_term
AU10_signal	Raw signal collected from the Turner Designs model AU-10 fluorometer	unitless	no_bcodmo_term
Chl_a_extract	Chlorophyll a concentration of the extracted water.	micrograms per Liter (ug/L)	chl_a
Chl_a_sample	Chlorophyll a concentration of the sample.	micrograms per Liter (ug/L)	chl_a
chl_a_avg	Average chlorophyll a concentrations from the sample.	micrograms per Liter (ug/L)	chl_a
chl_a_stdev	Standard deviation of the chlorophyll a concentrations from the sample.	micrograms per Liter (ug/L)	chl_a

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Database

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Dataset: EN589 Seawater Chlorophyll