UK Ocean Acidification Coastal Monitoring Network - Expanding the Network - Defra Contract C5801/ME5309

Scottish Marine and Freshwater Science Vol 5 No 1

The OSPAR ICES Study Group on Ocean Acidification (SGOA) and the Global Ocean Acidification Observing Network (GOA-ON) have both identified the need for a commitment to long-term monitoring at sites in coastal and inshore waters to distinguish long-term anthropogenic signals from short-term spatial and temporal variability. 2. Limited monitoring of the changes in ocean acidification is undertaken in coastal waters around the UK. A short UK Integrated Marine Observing Network (UK-IMON) demonstration study was commissioned to monitor coastal waters for the first half of 2013 for the carbonate chemistry parameters, Total Alkalinity (TA) and Dissolved inorganic carbon (DIC). 3. The project was divided into two distinct parts, namely a preliminary feasibility study, to examine the use of moored water samplers to collect water samples for the analysis of dissolved inorganic carbon (DIC), and discrete sampling at various locations around the UK for Total Alkalinty (TA) and DIC analysis. 4. Automated water samplers deployed on existing instrumented moorings may provide a cost effective means of collecting water samples for monitoring ocean acidification in coastal waters and a preliminary assessment of the utility of an automated water sampler for monitoring DIC was undertaken. A small but statistically significant difference was found between the concentrations of DIC measured in water samples collected simultaneously using an automated water sampler and rosette samples. At the present time it is not possible to determine whether this difference is due to the way samples are collected by the automated sampler or small differences in the way the two sets of samples were processed. 5. The authors recommend that a further, more detailed comparison should be undertaken to include a moored sampler with sample preservation. The introduction of a procedure to minimise aeration of samples during processing and filtration, together with any effect of long-term (weeks) storage of samples (during automated sampler deployment) on sample integrity should also be investigated.