| Title | Processed Dissolved Inorganic Carbon (DIC) and Total Alkalinity (TA) data from the Integrated Ecosystem Programme: Southern Benguela (IEP:SB) on Algoa Voyage 248, May 2018 |
|---|---|
| Project | Integrated Ecosystem Programme: Southern Benguela (IEP: SB) |
| Authors |
Mutshutshu Tsanwani |
| Publisher | Department of Forestry, Fisheries and the Environment (2025) |
| Contributors |
Contact Person: Mutshutshu Tsanwani Project Member: Baxolele Mdokwana |
| Abstract | This is processed Dissolved Inorganic Carbon (DIC) and Total Alkalinity (TA) data from the Integrated Ecosystem Programme cruise in the Southern Benguela (IEP-SB). The cruise took place from 15 to 21 May 2018 aboard the RV Algoa. A total of 44 stations were occupied along four transect lines on the west coast of South Africa. Ten Conductivity, Temperature, Depth (CTD) stations were occupied along the Kleinsee Monitoring Line (KML) of Kleinsee, ten along the Namaqua Monitoring Line (NML) of Namaqua, twelve stations along the St Helena Bay Monitoring Line (SHBML), two separate stations in the low oxygen zone in St Helena Bay, and ten stations along the Scarborough Monitoring Line (SCL) of Cape Columbine. Discrete water samples were collected in 500ml Certified Reference Materials (CRM) bottles from Niskin bottles and spiked with 0,02% of Mercuric chloride before being stored in the dark at room temperature for later analysis in the laboratory ashore using a Versatile INstrument for the Determination of Total inorganic carbon and titration Alkalinity (VINDTA). The purpose of the observations was to characterise ocean acidification conditions, monitor long-term changes with respect to ocean acidification, to detect long-term anthropogenically-driven changes in carbon chemistry and to identify spatial and temporal variations in the carbon chemistry on the west coast of South Africa. |
| Methods | Dissolved Inorganic Carbon (DIC) samples were drawn from Niskin bottles into either 500ml borosilicate glass flasks using silicone tubing according to the procedure outlined in the Guide to Best Practices for Ocean CO2 Measurements (www.ncei.noaa.gov/access/ocean-carbon-acidification-data-system/oceans/Handbook_2007.html). Bottles were rinsed three times and filled from the bottom. Trapped air bubbles were dislodged while overflowing by at least one-half volume. The sample tube was pinched off and withdrawn to create a headspace. 0,02% of saturated HgCl2 solution was added before bottles were sealed with glass stoppers. The Versatile INstrument for the Determination of Total Alkalinity (VINDTA 3C) system from Marianda in Germany was used to measure the DIC of seawater. The accuracy of the DIC measurement was determined by Certified Reference Materials (CRMs) supplied by Dr. Andrew Dickson of Scripps Institution of Oceanography. The CRM-certified DIC and AT values for batch 162 used were 2177.27µmol/kg and 2403.72µmol/kg respectively. Each day run started with 4-6 junks, 2-4 test samples, a CRM, followed by 15 samples and a CRM. CRMs and samples were equilibrated to 25°C before analysis. |
| Data | |
| Temporal extent | 15 May 2018 – 21 May 2018 |
| Geographic extent |
200 km Leaflet Tiles © Esri — Source: Esri, DeLorme, NAVTEQ, USGS, Intermap, iPC, NRCAN, Esri Japan, METI, Esri China (Hong Kong), Esri (Thailand), TomTom, 2012 Southern Benguela, West coast, South Africa
North: -29.0 |
| Keywords | Dissolved Inorganic Carbon, IEP, NISKIN BOTTLES, SDG 14.3.1 Average marine acidity (pH) measured at agreed suite of representative sampling stations, SDG Goal 14. Conserve and sustainably use the oceans, seas and marine resources for sustainable development, SOUTH ATLANTIC OCEAN, TA, Total Alkalinity |
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