This research has been carried under the Geological Survey Ireland 2017 Short Call. This call provided funding for researchers in academia or industry on the island of Ireland for projects of less than 12 months duration and less than €25,000.
Please note that the final report has been redacted to remove staff, financial and sensitive information. Some file sizes have been reduced to allow easier uploading/downloading, higher quality files are available on request. Supplemental information is also available on request in most cases. Please contact research[AT]gsi.ie
Disclaimer: The views expressed in this report are those of the author(s) and not of Geological Survey Ireland or the Department of Climate Action, Communications and Environment.
Lead Applicant: Dr Shane Regan
Host: Trinity College Dublin
Project Title: Iso-Mech (Development of a national groundwater isoscape for mechanistic recharge estimation and bacterial fingerprinting)
Project Description: In recent years, the concept of "isoscapes" has been used to describe spatiotemporal stable isotope distributions within natural environments including groundwater systems at multiple scales. They have effectively improved our understanding of the complex interactions between hydrological and biogeochemical cycles. Precipitation isoscapes drive isotopic patterns in surficial waters, however, less is known about the geological influence of recharge processes on stable isotopes in the subsurface. A recent study of the oxygen-18 (δ18O) groundwater isoscape in Ireland found that δ18O composition is primarily driven by location with respect to prevailing wind direction and annual precipitation volume, with a bias towards winter recharge. Results also indicate that local/regional hydrogeology exerts a secondary influence via infiltration/recharge mechanisms. However, the study was limited by the absence of deuterium (δD) measurements and temporal data; seasonal monitoring is necessary to confidently discern temporal patterns, while δD is required for quantification of evapotranspiration (δD excess). The proposed study (Iso-Mech) will seasonally analyse δ18O and δD from spatially distributed groundwater and rainfall stations to i) improve our understanding of precipitation origin, evaporative effects and estimated recharge rates, and ii) use results to conservatively trace bacterial (E. coli) ingress mechanisms with respect to the Irish groundwater environment.