Phosphorus in Irish aquifers : implications for input to surface waters

Abstract

This project examines phosphorus levels in a range of Irish hydrogeological situations, both to fill this gap in basic scientific knowledge, and to determine the circumstances in which concentrations likely to trigger eutrophication in surface waters are prone to occur. This research comprised an assessment of phosphorus (P) levels in a national dataset from the Environmental Protections Agency's national groundwater quality monitoring program and the detailed assessment of three catchment areas in the west of Ireland. The study areas were the Robe catchment in Co. Mayo, the Fergus catchment in Co. Clare and Co. Limerick. Nationally groundwater levels were generally low with a median value 17 μg 1 -1 of unfiltered molybdate reactive P. However, one quarter of the data were higher than the eutrophication threshold for Irish river (30 μg 1 -1). Groundwater P concentrations were evenly distributed across the country but sites with elevated groundwater P concentrations were generally located in the eastem half of the country.