Title: An investigation of uranium occurrence, sources and mobilization processes in selected Irish groundwaters
Researchers: Fani Papageorgiou, Prof. Frank McDermott
Geogenic uranium (U) contamination of drinking water can pose detrimental effects for human health. Ingestion of water with elevated concentrations of U (> 30 ppb, WHO 2005) can lead to nephritis which is a kidney related disease. The effects from uranium poisoning are due to its chemical toxicity rather than its radioactivity content. The 30 ppb provisional guideline from WHO (2005) was updated due to the higher amount of studies being conducted on humans. In Ireland, and more specifically in Baltinglass in 2001, elevated concentrations of U were documented both in public and private supplies of water, leading to concerns about public health. The contaminated public wells were shut down and new ones were drilled elsewhere to meet the public needs.
My project aims to identify areas with elevated U concentrations (>30 ppb, WHO 2005), particularly in private wells. It seeks to better understand and quantify hydrogeological and hydrochemical processes that control U mobilisation and transport in two distinct aquifer types in Ireland. Aims and objectives: Three areas linked to the geological settings of interest (Kerry/Limerick/Clare, Louth/Meath and Donegal) have been selected for an initial focus for the work based on our own preliminary studies, the published RPII/EPA data, local authority data and the Tellus Border project results.
Specifically we will investigate:
(i) uranium concentrations in wells in the North Kerry/Limerick/Clare area in order to understand the sources and mobilisation mechanisms of uranium in high pH (>7.5) groundwater in this region. Hypotheses to be tested in relation to elevated uranium in this region include: (a) that the source of the uranium is linked to groundwater recharge through glacial tills in the region that contain comminuted phosphatic Namurian shales, (b) that uranium concentrations in soil solutions and shallow groundwaters in the region are strongly controlled by pH dependent carbonyl complexes and (c) that a qualitative predictive model for dissolved uranium can be constructed based on glacial till type, bedrock lithology and soil pH.
(ii) uranium concentrations in private wells developed within fractured granites in Co. Donegal that are recharged through both relatively oxidising unconsolidated glacial moraine deposits containing granite fragments and through reducing peaty soils. The objective is to assess the extent to which private wells in the region are contaminated by geogenic uranium and to assess the role of secondary immobilisation within peat. The possible role of uranium transport by colloidal material (e.g. particulate organic carbon) will be a particular focus of this work.
(iii) uranium concentrations in groundwaters within selected lithologies of the Longford-Down terrane, guided initially by the Tellus Border data which shows high background U levels in the area.
(iv) use will also be made of existing EPA transects including New Village, Co. Galway (Granite) that are known to have elevated levels of uranium (>100 g/l). Private wells in the region will be included in the project.
(v) uranium concentrations in private wells in the Leinster Granite Batholith (SE Ireland) lead by previously documented elevated concentrations in Baltinglass, Co. Wicklow.