Assessment of urban groundwater: towards integrated hydrogeological and effects-based monitoring

Urban groundwater is a core resource to human health, and well-being, decisive for sustainable development. Extreme weather events and active release of man-made chemicals are increasing groundwater scarcity and loss of quality around the world. Surface and subsurface release of chemical contaminants are among the most compromising activities. Groundwater management thus requires sound monitoring assessment, supporting decision making to control contamination and assist rational water use as well. Integrated monitoring assessment, encompassing chemical and ecotoxicological tools, is nowadays recognised as the most effective to protect and manage water systems. Nevertheless, groundwater assessment is still relying mostly on hydrogeochemical and chemical analyses only. This approach is useful to identify the presence of pollutants and important ionic elements, and groundwater nature for different purposes. However, these analytical techniques are often very expensive, performed at researcher request and give limited or null information about detrimental effects of chemicals on the biota, as well as toxicological interactions of chemicals occurring in complex mixtures of contaminants frequently found in groundwater. Through research development and validation, a series of effect-based tools are now available for use in integrated chemical and biological evaluations. Cost effective in vitro and/or in vivo bioassays, as well as biomarkers, addressing different modes of action can be selected for suitable surveillance, operational or investigative monitoring. This work provides a synthesis of valuable effect-based tools suitable for integrated quality evaluation and presents an example of integrated assessment (hydrogeological, effects-based assays, GIS-based mapping) of an urban groundwater system in a fissured bedrock medium (Porto, NW Portugal) and its management advantages tackling water scarcity.