| Title | Carbonate chemistry time-series from discrete sampling at thirteen sites in Algoa Bay, South Africa, 2018 - 2020 |
|---|---|
| Authors |
Carla Edworthy Nicola C James |
| Publisher | Department of Forestry, Fisheries and the Environment (2022) |
| Contributors |
Contact Person: Carla Edworthy |
| Abstract | Coastal monthly carbonate chemistry data and other associated physico-chemical parameters from Algoa Bay, on the temperate south coast of South Africa. Eight offshore and five inshore sites were sampled. Temperature, salinity and dissolved oxygen were measured at each offshore site, and temperature was measured at each inshore site. At each offshore and inshore site, a single sea water sample was collected at the surface for later analysis of pH and total alkalinity (TA) in the laboratory. Remaining parameters of the carbonate system (including pCO2) were calculated in the software program CO2SYS (Lewis and Wallace, 1998) using pH and TA as input parameters. Temperature, salinity, silicate and phosphate concentrations were included in the calculations as supplemental data which may influence carbonate speciation. |
| Methods | These data were collected using primary monitoring of eight offshore (~ 30m depth) and five inshore intertidal (<1m depth) sites in Algoa Bay, South Africa. The sites were sampled monthly (weather dependent). The offshore sites were accessed by boat and at each site the temperature, salinity and DO were measured using a CTD (Seabird SBE 19plus). The inshore sites were accessed on foot by wading into the surf and at these sites temperature and salinity were measured manually using a hand-held thermometer and refractometer, respectively. At each offshore and inshore site, a single seawater sample was collected at the surface for later analysis of pH and TA in the laboratory (within 24 hours of sample collection when possible). pH was determined to the nearest 0.01 pH unit on the total scale using a spectrophotometric pH determination (as described in the standard operating procedures of Dickson et al., 2007, SOP 6b) and corrected to in situ temperature using CO2SYS. Total alkalinity (TA) was determined using a manual open cell titration (as described in the standard operating procedures of Dickson et al., 2007, SOP 3b). All laboratory analyses of pH and TA were conducted using the GOA-ON OA-in-a-box-kit (for details see http://www.goa-on.org/resources/kits.php). Remaining parameters of the carbonate system (including pCO2) were calculated in the software program CO2SYS (Lewis and Wallace, 1998) using pH and TA as input parameters. Temperature, salinity, silicate and phosphate (measured from triplicate surface samples using an auto-analyser Multitest MT19, Seal Analytical) concentration were included in the calculations as supplemental data which may influence carbonate speciation. The calculations used equilibrium constants from Merbach et al. (2973), refit by Dickson and Millero (1987) and KSO4 from Dickson (1990). Due to limited access to Certified Reference Materials (CRM's) no data quality control was possible. All data shown here should therefore be considered as raw measurements having undergone no quality control processing. |
| Data | |
| Temporal extent | 29 Aug 2018 – 08 Jan 2020 |
| Geographic extent |
Indian Ocean, South Africa
North: -33.711546 |
| Vertical extent |
Max: 0 m Min: -1 m |
| Keywords | carbonate chemistry, Coastal acidification, monitoring, pH, SDG 14.3.1 Average marine acidity (pH) measured at agreed suite of representative sampling stations |