Dataset: Gulf of Finland CDOM Absorption Coefficients

Name: Chromophoric Dissolved Organic Matter (CDOM) Naperian Absorption Coefficients from the Gulf of Finland from June to July 2019 (MODIE project)
Published: 2024-03-07
Keywords: oceans

Cite This Dataset

DOI:10.26008/1912/bco-dmo.921060.1

Spatial Extent: N:59.843144 E:23.260337 S:59.843144 W:23.260337

The Tvärminne Mesocosm Facility in the Western Gulf of Finland, northern Baltic Sea, a brackish water estuarine environment

Temporal Extent: 2019-06-26 - 2019-07-08

Project:

Transforming our understanding of DIC Photoproduction in Oceanic Waters (MODIE)

Principal Investigator:

Jay Brandes (Skidaway Institute of Oceanography, SkIO)

Contact:

Kun Ma (Woods Hole Oceanographic Institution, WHOI)

Data Manager:

Kun Ma (Skidaway Institute of Oceanography, SkIO)

BCO-DMO Data Manager:

Sawyer Newman (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Version:

Version Date:

2024-03-07

Restricted:

Validated:

Yes

Current State:

Final no updates expected

Chromophoric Dissolved Organic Matter (CDOM) Naperian Absorption Coefficients from the Gulf of Finland from June to July 2019 (MODIE project)

Abstract:

These data are chromophoric dissolved organic matter (CDOM) Naperian absorption coefficients from the LightCycle DOM photodegradation experiments conducted in the western Gulf of Finland, Baltic Sea. The LightCycle experiments were conducted as a part of the AQUACOSM JOMEX project: Systems Responses to A Pulse of Dissolved Organic Carbon, at the Tvärminne Mesocosm Facility (TMF, Tvärminne Zoological Station (TZS), University of Helsinki). The JOMEX experiment ran from 26 June to 10 July 2019 and the mesocosms were divided into three treatment groups: 1) three control mesocosms with no humic substances or nutrients added, 2) three humic-amended mesocosms with only humic substances added to a final concentration of 2 mg L−1 in each mesocosm and three humic+nutrients-amended mesocosms with humic substances (2 mg L−1 final concentration), and 3) three humic+nutrients-amended mesocosms with humic substances (2 mg L−1 final concentration) and NH4Cl and KH2PO4 (80 μg L−1 N and 20 μg L−1 P final concentrations) added. Surface (1 m) water samples for the LightCycle experiments were collected from one each of control, humic-amended and humic+nutrients-amended mesocosms, immediately after the amendment (day 1) and 2, 5, 7, 9 and 12 days after the amendment (days 3, 6, 8, 10 and 13). These water samples were filtered with 0.2μm filters and irradiated under a solar simulator. CDOM absorbance at different irradiation time points were measured for these experiments using a Shimadzu UV-2501PC UV-VIS recording spectrophotometer or an Agilent 8453 UV-visible Spectrophotometer, and converted to Naperian absorption coefficients. The measurements of CDOM absorption and the subsequent calculation of CDOM fading (decrease in absorption) offered clues to the degradation of CDOM, and provided insights into the potential of photochemistry to remove added terrestrial dissolved organic matter (DOM) and the interactions of DOM photochemistry with eutrophication in this Baltic Sea system, where there are increasing concerns that climate change and anthropogenic activities can lead to increased terrestrial input of humic substances to surface waters and browning of surface waters. These data were collected by Kun Ma and Jay Brandes of the Skidaway Institute of Oceanography, Department of Marine Sciences, University of Georgia.

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Archival Copy

Version Date	Archive	Persistent Identifier (PID)	Date PID Issued
2024-03-07	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.26008/1912/bco-dmo.921060.1	2024-06-18

Methods & Sampling

Surface (1 m) water samples were collected using precleaned 10 L HDPE canisters (Plastex®, Finland) and then filtered through 0.2 μm Whatman Polycap 36 AS nylon membrane cartridge filters, using a Masterflex L/S Digital Standard Drive peristaltic pump with Easy Load II and Masterflex L/S 17 silicone tubing at 100 mL min−1, directly into precleaned 10 L polyethylene Hedwin CubitainersTM. Filtered sample waters were stored in the dark in an environmental chamber set at temperatures matching the in situ temperatures before use.

Samples from each treatment group were partitioned into six 10-cm-pathlength cylindrical Spectrocell spectrophotometric quartz cells (~30 mL volume each). Each cell was rinsed three times with sample water from the corresponding cubitainers, and then filled without headspace directly from the cubitainers. Each cell was capped with two Spectrocell caps fitted with Microsolv Teflon-lined butyl septa. Five cells for each treatment type (15 total) were placed vertically into a temperature (15°C)-controlled black aluminum block, and irradiated under an Atlas Suntest CPS+ solar simulator equipped with a 1.5 kW xenon lamp. The solar simulator was fitted with a daylight filter (excluding light below ~300 nm) to provide the cells with precisely known, full spectral light. One cell for each treatment type was wrapped in aluminum foil to serve as dark control and placed in the same water bath that provided cooling water to the aluminum block. Absorbance (A(λ)) in the control and irradiated samples were measured at 250–800 nm at 1.0 nm intervals, in duplicate, in a 1-cm-pathlength quartz spectrophotometric cuvette. At the Tvärminne Zoological Station, a Shimadzu UV-2501PC UV-VIS recording spectrophotometer with UV-Probe software was used, with air as an internal reference and Milli-Q water as blanks.

At Skidaway Institute of Oceanography, absorbances were measured using an Agilent 8453 UV-visible spectrophotometer with ChemStation software, with the same parameters as above and Milli-Q water as blanks. The average absorbance spectra of blanks were subtracted from the absorbance spectra of the sample water. Absorbance spectra were further corrected for potential offsets and instrument drift by subtracting the average absorbance at 690–710 nm, before converting A(λ) to Napierian absorption coefficients (ag(λ); m−1), using the following equation: ag(λ)= A(λ) ln10/L, where L (m) is the pathlength.

Data Processing Description

Data processing and calculation details:

The average absorbance spectra of blanks were subtracted from the absorbance spectra of the sample water.

Absorbance spectra were further corrected for potential offsets and instrument drift by subtracting the average absorbance at 690–710 nm.

A(λ) was converted to Napierian absorption coefficients (ag(λ); m−1), using the following equation: ag(λ)= A(λ) ln10/L, where L (m) is the pathlength.

R version used for programming:

R-4.0.0 (2020-04-24) - R-4.1.1(2021-08-12),

R packages used within R environment:

Package broom:
Robinson D, Hayes A, Couch S (2023). broom: Convert Statistical Objects into Tidy Tibbles. R package version 1.0.5, https://CRAN.R-project.org/package=broom

Package stringr:
Wickham H (2022). stringr: Simple, Consistent Wrappers for Common String Operations. R package version 1.5.0, https://CRAN.R-project.org/package=stringr>

BCO-DMO Processing

- Merged seperate data tables, each representing 1 day from the experiment, into one file representing all experimental days, with an additional column representing the specific day of the experiment (Experiment_day)
- Added Absorbance_wavelength_location before numeric value indicating wavelength location of absorbance measurement columns
- Added a column indicating the date of the experiment (Experiment_date)

Data Files

File
921060_v1_Gulf_of_Finland_CDOM_Absorption_Coefficients.csv (Comma Separated Values (.csv), 841.27 KB) MD5:d15c164648b6fe78ffaa1fd1b739b094 Primary data file for dataset ID 921060, version 1

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-1635618

Deployments

None available yet

Instruments

Spectrophotometer

Supplied Name: Shimadzu UV-2501PC UV-VIS Recording Spectrophotometer

Supplied Description:

Shimadzu UV-2501PC UV-VIS recording spectrophotometer with UV-Probe software and Agilent 8453 UV-visible spectrophotometer with ChemStation software: chromophoric dissolved organic matter absorbance measurements.

At the Tvärminne Zoological Station, a Shimadzu UV-2501PC UV-VIS recording spectrophotometer with UV-Probe software was used, with air as an internal reference and Milli-Q water as blanks.

Absorbance (A(λ)) in the control and irradiated samples were measured at 250–800 nm at 1.0 nm intervals, in duplicate, in a 1-cm-pathlength quartz spectrophotometric cuvette.

Instrument Type

Generic Name: Spectrophotometer

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/LAB20/

Generic Description:

An instrument used to measure the relative absorption of electromagnetic radiation of different wavelengths in the near infra-red, visible and ultraviolet wavebands by samples.