Dataset: DIC and TA sediment fluxes 2017-2018

Name: Dissolved inorganic carbon and total alkalinity fluxes from sediment incubation experiments during four R/V Pelican cruises to the Louisiana shelf in 2017 and 2018
Published: 2023-05-30
Keywords: sediment-water exchange, DIC flux, Hurricane Harvey, Louisiana Shelf, oceans

Cite This Dataset

DOI:10.26008/1912/bco-dmo.896598.1

Spatial Extent: N:28.8732 E:-90.48246 S:28.50066 W:-94.29978

Temporal Extent: 2017-04-05 - 2018-01-26

Project:

Collaborative Research: A RAPID response to Hurricane Harvey's impacts on coastal carbon cycle, metabolic balance and ocean acidification (HarveyCarbonCycle)

Principal Investigator:

John Lehrter (University of South Alabama; and Dauphin Island Sea Lab, USA-DISL)

Student:

Mai Fung (University of South Alabama; and Dauphin Island Sea Lab, USA-DISL)

Alexis Hagemeyer (University of South Alabama; and Dauphin Island Sea Lab, USA-DISL)

BCO-DMO Data Manager:

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

Version:

Version Date:

2023-05-30

Restricted:

Validated:

Yes

Current State:

Final no updates expected

Dissolved inorganic carbon and total alkalinity fluxes from sediment incubation experiments during four R/V Pelican cruises to the Louisiana shelf in 2017 and 2018

Abstract:

These data include the measurements of dissolved inorganic carbon (DIC) and total alkalinity (TA) fluxes from sediment incubation experiments at several sites on the Louisiana shelf. Data were collected during four cruises in 2017 and 2018. Cruises were conducted aboard the R/V Pelican in April (PE17-18), July (PE18-02), and September-October (PE18-11) of 2017 and January of 2018 (PE18-19). The study domain included the Louisiana and Texas continental shelf from the Mississippi River Bird's Foot delta to south of Galveston Bay. The objective of this work was to quantify how hurricanes and tropical storms affect metabolic rates and the concentrations of oxygen and DIC/pH. These data assess the sediment metabolism response before and after Hurricane Harvey and were collected by Dr. John Lehrter of the University of South Alabama.

Expand/Collapse All

Archival Copy

Version Date	Archive	Persistent Identifier	Date Assigned
2023-05-30	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.26008/1912/bco-dmo.896598.1	2023-07-21

Methods & Sampling

At each site during the R/V Pelican cruises, a box corer was used to collect surface sediment. The box core was subsampled in triplicate using 40 cm acrylic tubes that were pushed into the sediment to refusal, i.e. 20-30 cm. Cores were extracted in the acrylic tubes, capped on the bottom with an acrylic cap and o-ring, and submerged in a dark incubator filled with bottom water collected at the site. Each core was carefully filled with in situ near bottom water with minimum disturbance to the sediment-water interface and closed to ensure no visible headspace or air bubbles at the top. The submerged cores were allowed to equilibrate with the water in the incubator for 12 hours. A control was included that was an acrylic liner filled with bottom water only. Following this equilibration step, the cores were capped on their tops with an acrylic cap and o-ring. The top caps contained two sampling ports that were opened to collect water samples from the water overlying the sediments in the core tubes. The overlying water was mixed by a slowly turning magnetic stir bar suspended from the top cap. All cores were attached to a reservoir containing bottom water for gravity driven replenishment of water inside the core tubes during sampling. After capping, sampling commenced.

Samples for DIC were taken every 4-8 hours for up to 23 hours (4-6 time points) from the four cores, i.e. one control core with bottom water only (identified as ‘Control’) and three cores with sediments and bottom water (identified as ‘Rep1’, ‘Rep2’, and ‘Rep3’). Dissolved inorganic carbon (DIC) and total alkalinity (TA) concentrations were analyzed in each sample by Wei Jun Cai’s lab at the University of Delaware. For DIC, 1 ml of water sample was measured in triplicate with an infrared CO2 detector-based DIC analyzer (AS-C3 Apollo Scitech). For TA, a 25 ml water sample was measured in duplicate with the open-cell Gran titration method using a temperature-controlled, semi-automated titrator (AS-ALK2 Apollo Scitech). Certified Reference Materials provided by A. G. Dickson, Scripps Institution of Oceanography, were analyzed for DIC and TA for quality control.

Detailed methods are provided in Wang et al. (2020) and Lehrter et al. (2012).

Problem report: Data for a few time points are missing due to lost or broken sample containers. For 1801 C6, there is missing data, so assumed depths are presented based on the depths similar to the last sampling on cruise 1710 C6-2.

Data Processing Description

Sediment-water exchanges, i.e., fluxes, were calculated based on the rate of change in the DIC concentrations over time. Slopes were calculated for the rate of change for each core with sediments and for the core with bottom water only. The net flux was then calculated as the difference between mean of the sediment core slopes and the control slope.

Data Files

File
sed_flux_dic_totalk.csv (Comma Separated Values (.csv), 50.02 KB) MD5:31015360eb85610a5a64705620a56503 Sediment flux of DIC and Total Alkalinity

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-1760747

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
PE17-18	GOM_UW_1704 GOM_CTD_1704	2017-04-05	R/V Pelican	Baoshan Chen (Chief Scientist)	data info
PE18-02	GOM_CTD_1707	2017-07-07	R/V Pelican	Wei-Jun Cai (Chief Scientist)	data info
PE18-11	GOM_CTD_1710 GOM_Discrete_1710 GOM_Discrete_1710	2017-09-28	R/V Pelican	Baoshan Chen (Chief Scientist)	data info
PE18-19	GOM_CTD_1801	2018-01-17	R/V Pelican	Wei-Jun Cai (Chief Scientist)	data info

Instruments

Apollo SciTech AS-ALK2 total alkalinity titrator

Supplied Name: AS-ALK2 Apollo Scitec

Supplied Description:

For total alkalinity, a 25 ml water sample was measured in duplicate with the open-cell Gran titration method using a temperature-controlled, semi-automated titrator (AS-ALK2 Apollo Scitech).

Instrument Type

Generic Name: Apollo SciTech AS-ALK2 total alkalinity titrator

Acronym: Apollo SciTech AS-ALK2

Generic Description:

An automated acid-base titrator for use in aquatic carbon dioxide parameter analysis. The titrator provides standardisation and sample analysis, using the Gran titration procedure for alkalinity determination of seawater and brackish waters. It is designed for both shipboard and land based laboratory use. The precision of the instrument is 0.1 percent or higher, and sample volumes may range from 10-25 ml. Titration takes approximately 8 minutes per sample, and the repeatability is within plus or minus 1-2 micromoles per kg.

Apollo SciTech AS-C3 Dissolved Inorganic Carbon (DIC) analyzer

Supplied Description:

For DIC, 1 milliliter of water sample was measured in triplicate with an infrared CO2 detector-based DIC analyzer (Apollo SciTech AS-C3 Dissolved Inorganic Carbon analyzer).

Instrument Type

Generic Name: Apollo SciTech AS-C3 Dissolved Inorganic Carbon (DIC) analyzer

Acronym: Apollo SciTech AS-C3

Generic Description:

A Dissolved Inorganic Carbon (DIC) analyzer, for use in aquatic carbon dioxide parameter analysis of coastal waters, sediment pore-waters, and time-series incubation samples. The analyzer consists of a solid state infrared CO2 detector, a mass-flow controller, and a digital pump for transferring accurate amounts of reagent and sample. The analyzer uses an electronic cooling system to keep the reactor temperature below 3 degrees Celsius, and a Nafion dry tube to reduce the water vapour and keep the analyzer drift-free and maintenance-free for longer. The analyzer can handle sample volumes from 0.1 - 1.5 milliliters, however the best results are obtained from sample volumes between 0.5 - 1 milliliters. It takes approximately 3 minutes per analysis, and measurement precision is plus or minus 2 micromoles per kilogram or higher for surface seawater. It is designed for both land based and shipboard laboratory use.

Box Corer

Supplied Name: box corer

Supplied Description:

At each site, a box corer was used to collect surface sediment.

Instrument Type

Generic Name: Box Corer

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/51/

Generic Description:

General description of a box corer:

A box corer is a marine geological tool that recovers undisturbed soft surface sediments. It is designed for minimum disturbance of the sediment surface by bow wave effects. Traditionally, it consists of a weighted stem fitted to a square sampling box. The corer is lowered vertically until it impacts with the seabed. At this point the instrument is triggered by a trip as the main coring stem passes through its frame. While pulling the corer out of the sediment a spade swings underneath the sample to prevent loss. When hauled back on board, the spade is under the box. (definition from the SeaVox Device Catalog)

Box corers are one of the simplest and most commonly used types of sediment corers. The stainless steel sampling box can contain a surface sediment block as large as 50cm x 50cm x 75cm with negligible disturbance. Once the sediment is recovered onboard, the sediment box can be detached from the frame and taken to a laboratory for subsampling and further analysis. The core sample size is controlled by the speed at which the corer is lowered into the ocean bottom. When the bottom is firm, a higher speed is required to obtain a complete sample. A depth pinger or other depth indicator is generally used to determine when the box is completely filled with sediment. Once the core box is filled with sediment, the sample is secured by moving the spade-closing lever arm to lower the cutting edge of the spade into the sediment, until the spade completely covers the bottom of the sediment box. (definition from Woods Hole Oceanographic Institution).

circulating water bath

Supplied Name: temperature-controlled recirculating water bath incubator

Supplied Description:

Immediately after collection, three incubation cores per station were immersed in a temperature-controlled recirculating water bath incubator adjusted to the recorded bottom water temperature.

Instrument Type

Generic Name: circulating water bath

Generic Description:

A device designed to regulate the temperature of a vessel by bathing it in water held at the desired temperature. [Definition Source: NCI]

Parameters

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

Supplied Name	Supplied description	Supplied Units	Standard Name
Cruise	Cruise ID	unitless	cruise_id
Station	Station ID where samples were collected	unitless	station
Latitude	Latitude of station	decimal degrees	lat
Longitude	Longitude of station	decimal degrees	lon
ISO_DateTime_UTC	Datetime of sampling Format: %Y-%m-%dT%H:%M:%SZ	unitless	ISO_DateTime_UTC
Bottle_number	Sample ID tracking bottle number for each cruise	unitless	bottle
DIC_conc_volume	DIC concentration (volumetric)	micromoles per liter (umol/L)	DIC
Salinity	Salinity of water sample	unitless	sal
Density	Density of water sample	kilogram per liter (kg/L)	density
DIC_conc_weight	DIC concentration (weight)	micromoles per kilogram (umol/kg)	DIC
TA	Total Alkalinity concentration	micromoles per kilogram (umol/kg)	TALK
Rep	Sample replicate names where Rep 1, Rep 2, Rep 3 for sediment cores and Control for cores with bottom water only	unitless	replicate
DateTime_local	Local datetime of sampling Format: %Y-%m-%d %H:%M:%S	unitless	DateTime
Overlying_Water_Depth	Depth of the bottom water within the sampling tubes	meters	depth
Bottom_Depth	Depth of the seafloor at sampling site	meters	depth_bottom
CruiseStation	Cruise and Station ID combination	unitless	site
Date_Sediment_Collection	Date of sediment collection	unitless	date
Comments	Comments	unitless	comment

Database

Contribute Data

Dataset: DIC and TA sediment fluxes 2017-2018