Research 183: Assessing and Developing Natural Background Levels for Chemical Parameters in Irish Groundwater

Authors: Katie Tedd, Catherine Coxon, Bruce Misstear, Donal Daly, Matthew Craig, Anthony Mannix and Taly Hunter Williams

Summary: This report details Assessing and Developing Natural Background Levels for Chemical Parameters in Irish Groundwater

Published: 2017

ISBN: 978-1-84095-659-7

Pages: 183

Filesize: 6,627KB

Format: pdf

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Identifying Pressures

The natural background levels established in this report are the range in concentration of chemical parameters in Irish groundwater arising from natural processes. They provide a reference against which to assess whether anthropogenic pollution of groundwater is taking place and potential impacts on an aquifer. They are therefore essential for understanding pollution and for setting regulatory limits. The research fellowship used a pre-selected dataset to exclude groundwater with significant anthropogenic pressures, and identified the pressures using GIS data layers relating to anthropogenic activities.

Informing Policy

In Ireland, the status of groundwater is assessed via the EU Water Framework Directive (WFD 2000/60/EC) which stipulates that groundwater status must be assessed and that good chemical and quantitative status must be achieved in order to protect human health and associated dependent ecosystems. The Groundwater Daughter Directive (GWDD 2006/118/EC) explicitly asks Member States to consider natural background levels when establishing Threshold Values for groundwater pollutants which are used to assess the chemical status of groundwater bodies. The 2014 amendments of the GWDD Annexes placed much greater emphasis on natural background levels. This research fellowship establishes or updates natural background levels for forty parameters, which may be used to set or update Threshold Values.

Developing Solutions

A methodology to establish natural background levels in Irish groundwater was developed following international best practice. Natural background levels were established for forty parameters, comprising field parameters, major ion, minor ions, nutrients and trace elements. This study used a pre-selected datasets of the EPA groundwater quality monitoring data. The most likely hydrogeological and hydrochemical controls for each parameter were considered and the natural background levels were defined accordingly. The natural background levels have made best use of the available data and the results are comparable to natural background levels established in other countries or regions.