Groundwater Baseline Quality

Abstract

Naturally occurring groundwaters are becoming increasingly impacted by human infl uences. It is important to develop criteria to recognise the extent and baseline characteristics of groundwater bodies as a basis of management and specifi cally as a starting point to recognise pollution. The baseline concept is reviewed and a defi nition adopted for use in the chapters of this book. Emphasis is placed on developing a sound understanding of the spatial and temporal distribution of water quality, in relation to hydrogeological and geochemical controls. The main geochemical controls on natural baseline chemistry, which usually accounts for 98% of the mineral composition of groundwater, are outlined. The various approaches available for baseline defi nition are then reviewed. Statistical tools are used as a fi rst step, but cannot explain the variance in the data for which a resort to the fi eld situation and use of historical data is required. The median and 97.7 percentile are adopted as the main statistical parameters for initially defi ning baseline and comparing different data sets.

Separating baseline conditions from anthropogenic impacts: example of the Damour coastal aquifer (Lebanon)

“…Their multitude of water quality problems has generated many studies, for instance by Mandel et al (1972), Kafri and Arad (1979), Stigter et al (1998), Tulipano et al (2005), Kempe et al (2006), Abdul Rahman (2007), Weinstein et al (2007), and El-Fiky (2010). Water quality problems also call for an assessment of baseline conditions of such aquifers, for several reasons (Edmunds and Shand 2008): (a) to be able to assess quantitatively whether or not anthropogenic pollution is taking place, (b) to improve groundwater monitoring systems, (c) to breach guidelines for potable water quality when the concentration of certain elements is quite natural, (d) to define zones of uncontaminated water and protect these areas better, and (e) to provide guidelines for new policy, engagement with end users such as water utilities, and the general public. This need is even more acute for coastal karstic aquifers, because of their extreme vulnerability to salinization and other sources of pollution (Tulipano et al 2005).…”

“…The term "baseline" is defined in this study as "the range of concentrations of a given element, isotope or chemical compound in solution, derived entirely from natural, geological, biological or atmospheric sources, under conditions not perturbed by anthropogenic activity" (Edmunds and Shand 2008).…”

Application of stable isotopes (δ34S-SO4, δ18O-SO4, δ15N-NO3, δ18O-NO3) to determine natural background and contamination sources in the Guadalhorce River Basin (southern Spain)

“…Hence, NBLs are the result of numerous natural factors, such as geology of the area, water-rock interaction, the residence time of groundwater, recharge by rainfall, and relations with other aquifers. In addition, variation of concentrations with space and depth are often observed within a single groundwater body (Edmunds and Shand, 2008).…”

Aquifer Recharge Estimation through Atmospheric Chloride Mass Balance at Las Cañadas Caldera, Tenerife, Canary Islands, Spain

“…The main atmospheric chloride sources are the marine aerosol dissolved in precipitation, salts contained in terrestrial dust, and natural and artificial volatile chloride compounds [51,52].…”