Conference Contribution Details
Mandatory Fields
McGrath, T.; McGovern, E.; Cave, R.R.
Marine Chemistry Working Group 2016
Title of presentation: The inorganic carbon chemistry in Irish coastal, shelf and offshore water. This was an overview of all carbonate chemistry research to date that has been carried out in Ireland.
Marine Institute, Galway
Invited Oral Presentation
Optional Fields
There are three key areas of research being carried out at the Marine Institute, Ireland and NUI Galway in relation to the inorganic carbon chemistry in Irish waters. The first is a time series along a transect across the Rockall Trough, in operation since 2009, where dissolved inorganic carbon (DIC) and total alkalinity (TA) have been sampled alongside nutrients, dissolved oxygen and salinity. The rest of the CO2 system (pH, pCO2 and calcium carbonate saturation) was then calculated using CO2SYS to determine rates of acidification in the region. The data collected between 2009 and 2013 has been compared with WOCE data collected in the Rockall Trough in the 1990s (McGrath et al., 2012). Surface waters are acidifying at a rate of -0.02 pH units per decade due to increasing levels of CO2 dissolving into the ocean from the atmosphere. Anthropogenic carbon is also increasing in Labrador Sea Water, a prominent deep water mass in the Trough, with subsequent decrease in pH and saturation of calcium carbonate minerals, calcite and aragonite. The second area of research is an ongoing winter time series of inorganic carbon chemistry in Irish coastal waters, which has indicated very large spatial variability in carbonate parameters around the coastline which is largely related to the type of bedrock of the local rivers (McGrath et al., 2015). Rivers with limestone bedrock have a very high concentration of TA and DIC due to inputs of bicarbonate from erosion of the calcium carbonate bedrock, with positive correlations with salinity. Rivers with non-limestone bedrock have negative correlations between salinity and TA and DIC. This in turn affects the local inorganic carbon chemistry, pCO2 and calcium carbonate saturation state around the coastline. The third area of research is a current postdoctorate project where a publication of results is currently in preparation. Here, three inshore sites with contrasting carbon system properties were selected along the coastline, which were sampled once in winter and three times during the productive season between April and September. Results highlighted spatial differences in TA-salinity regressions depending on local bedrock and distinctly lower DIC regressions in spring-summer months due to primary production. Aragonite saturation is at a minimum in winter time at all sites, coinciding with higher DIC. Future monitoring will determine where future acidification will lower the aragonite saturation at these sites and potentially impact the local ecosystem, particularly the local shellfish farms.
Publication Themes
Environment, Marine and Energy