Dataset: Cruise optical properties: Absorbance
Deployment: HRS1608

View Data: For data, See Dataset Metadata Page: https://www.bco-dmo.org/dataset/938783

Principal Investigator:

Michael Gonsior (University of Maryland Center for Environmental Science, UMCES)

Co-Principal Investigator:

Neil V. Blough (University of Maryland - College Park, UMD)

Rossana Del Vecchio (University of Maryland - College Park, UMD)

Scientist:

Leanne Powers (University of Maryland Center for Environmental Science, UMCES)

BCO-DMO Data Manager:

Amber D. York (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Project:

Collaborative Research: Phlorotannins - An Important Source of Marine Chromophoric Dissolved Organic Matter? (Sargassum DOM)

Version:

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Description

Methods & Sampling

Dataset acquisition description

Samples were transferred from Niskin bottles to clean 10L low-density polyethylene cubitainers using silicon tubing. Containers were rinsed three times with sample before final collection.

Sampling and analytical procedures:

Subsamples for fluorescence and absorbance were 0.2 µm filtered using Whatman GD/X cellulose acetate syringe filters. Filters were rinsed with ~20mL sample before collecting samples in combusted 40mL amber glass vials. See "Related Datasets" section for the fluorescence data. Samples stored at 4°C until analysis (within 1 week of collection). For fluorescence and absorbance measurements, samples were transferred to 1 cm quartz fluorescence cuvette and analyzed using a Horiba Aqualog spectrofluorometer. Absorbance was recorded from excitation wavelengths 240 to 600 at 3 nm intervals. Fluorescence emission was recorded from ~243 to 297 nm at fixed ~3.3 nm intervals to created excitation-emission matrix (EEM) spectra. Integration time = 2s. Ultrapure water used as the fluorescence blank and was subtracted from all EEM spectra.

Data Processing Description

Dataset Processing Description

Absorbance .dat files (see "Supplemental Files" section): the only data used from these files for this dataset are the first column (Wavelength in nm) and the second to last column (column J, Abs, OD, which is the blank corrected absorbance, OD refers to optical density and is unitless).

Blank corrected absorbance spectra (A(λ)) were converted to Naperian absorption coefficient spectra (a(λ)) using the equation a(λ) = 2.303xa(λ)/L where L = 0.01 m. Spectral slopes were determined from 275-295 nm (S(275-295)) and from 350 – 400 nm (S(350-400)) as the slope of the log-normalized absorbance spectrum from 275-295 nm and 350-400 nm, respectively. Slope ratio (SR) is the ratio of S(275-295) to S(350-400) as defined previously (Helms et al. 2008). E2:E3 ratio is the ratio of absorbance at 250 nm to that 365 nm (De Haan and De Boer 1987).

More information about this dataset deployment

Funding

Award Number	Funding Source
OCE-1536888	NSF Division of Ocean Sciences
OCE-1536927	NSF Division of Ocean Sciences

Instruments

Spectrometer

Supplied Name: Horiba Aqualog spectrofluorometer

Supplied Description:

Instrument Type

Generic Name: Spectrometer

Community Identifier: http://vocab.nerc.ac.uk/collection/L22/current/TOOL0460/

Generic Description:

A spectrometer is an optical instrument used to measure properties of light over a specific portion of the electromagnetic spectrum.

Parameters

Supplied Name	Supplied description	Supplied Units	Standard Name
date	Sampling date	unitless	date
Time	Time of cast (in UTC time zone)	unitless	time
ISO_DateTime_UTC	DateTime of cast with time zone (in ISO 8601 format)	unitless	ISO_DateTime_UTC
Lat	Latitude	decimal degrees	lat
Long	Longitude	decimal degrees	lon
Salinity	Salinity. Practical Salinity Scale 1978 (PSS-78)	unitless	sal
depth_sample	sampling depth	meters (m)	depth
depth_sample_comment	sampling depth description (e.g. "Chl max")	unitless	sample_descrip
file_name	associated absorbance file (.dat). These files are included in SharpCruise_optics_abs.zip (See supplemental files).	unitless	file_name
E2_to_E3	E2:E3. Ratio of A(250)/A(364)	unitless	no_bcodmo_term
E2_to_E3_flag	Flag column for the E2_to_E3 column. "BD" indicates the E2_to_E3 value is missing due to being below the detection limit.	unitless	no_bcodmo_term
S275_to_295	S(275-295). spectral slope from 275-295 nm	1/nm	no_bcodmo_term
S275_to_295_flag	Flag column for the S275_to_295 column. "BD" indicates the S275_to_295 value is missing due to being below the detection limit.	unitless	no_bcodmo_term
S350_to_400	S(350-400). spectral slope from 350-400 nm	1/nm	no_bcodmo_term
S350_to_400_flag	Flag column for the S350_to_400 column. "BD" indicates the S350_to_400 value is missing due to being below the detection limit.	unitless	no_bcodmo_term
S_R	ratio of S(275-295)/S(350-400)	unitless	no_bcodmo_term
S_R_flag	Flag column for the S_R column. Indicates BD if the S_R value is missing due to being below the detection limit.	unitless	no_bcodmo_term

Database

Contribute Data

Dataset: Cruise optical properties: Absorbance
Deployment: HRS1608

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: Cruise optical properties: AbsorbanceDeployment: HRS1608

Dataset acquisition description

Dataset Processing Description

Dataset: Cruise optical properties: Absorbance
Deployment: HRS1608