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Front. Environ. Sci. | doi: 10.3389/fenvs.2018.00154

Arsenic in groundwater in south west Ireland: occurrence, controls and hydrochemistry

 Liam Morrison1, 2*,  Ellen McGrory2, Emma Holian3, Alberto Alvarez-Iglesias4, Norma Bargary5,  Eoin McGillicuddy6,  Tiernan Henry2 and Eve Daly2
  • 1National University of Ireland Galway, Ireland
  • 2Department of Earth and Ocean Sciences, School of Natural Sciences, National University of Ireland, Ireland
  • 3School of Mathematics, Statistics, and Applied Mathematics, College of Science, National University of Ireland Galway, Ireland
  • 4HRB Clinical Research Facility, National University of Ireland, Galway, Ireland
  • 5Department of Mathematics and Statistics, University of Limerick, Ireland
  • 6Centre for Health from Environment, Ryan Institute, National University of Ireland, Ireland

Globally numerous regions have been identified with elevated arsenic within groundwater which can result in potential adverse health risks. In Ireland, a previous national-scale research assessment of groundwater identified isolated clusters of elevated arsenic and indicated that lithology was a major controlling factor on arsenic in groundwater. Complementary comparisons of national-scale and regional-scale groundwater assessments of arsenic are lacking in Europe when compared to other global regions. The aims of this study were to demonstrate the value of a regional-scale groundwater hydrochemistry dataset with an existing national-scale approach, describe anomalies that can become the focus of attention for public health and economic reasons, and to provide a wider context for arsenic in groundwater within Ireland and Europe. Regional-scale data using 470 locations comprising 1493 analyses using several hydrochemical parameters (arsenic, pH, conductivity, iron, manganese, sodium, potassium, calcium, magnesium, and total hardness) in south west Ireland were integrated with geological, hydrogeological, and land use datasets. Statistical analysis was performed using a combination of methods including score tests of geological groups using an empirical cumulative distribution function plot in addition to spatial analysis. Results revealed that hydrochemical parameters exhibited different spatial clusters, which was generally associated with lithology. Arsenic was elevated in sandstone derived bedrock. Weak correlation of arsenic with other hydrochemical parameters were observed and redox-sensitive elements like manganese and iron showed a greater diversity in spatial occurrence. This study has shown that the variation of hydrochemical parameters are controlled by regional geology. Finally, the paper focuses on anomalies identified by concentrations of individual ions or statistical associations in the context of, for example, historical mineral exploration and mining in the area and also discusses whether groundwater chemistry sampling on this scale can assist in future mineral exploration, as well as guiding the future development of high quality public and private water supplies.

Keywords: Arsenic, Geology, spatial analysis, Groundwater, Iron, Manganese

Received: 31 Aug 2018; Accepted: 03 Dec 2018.

Edited by:

Prosun Bhattacharya, Royal Institute of Technology, Sweden

Reviewed by:

Ratan K. Dhar, York College, City University of New York, United States
Barbora Doušová, University of Chemistry and Technology in Prague, Czechia  

Copyright: © 2018 Morrison, McGrory, Holian, Alvarez-Iglesias, Bargary, McGillicuddy, Henry and Daly. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Liam Morrison, National University of Ireland Galway, Galway, Ireland, liam.morrison@nuigalway.ie