Climate change and groundwater contamination: out-of-sight and hidden threat

Climate change potentially causes the extreme hydrologic events which affect the groundwater contamination. Climate change significantly causes changes in surface water levels and quality, and due to the dynamics of surface water-groundwater interactions, there may be "hidden threats" to the quantity and quality of groundwater resources. This review proposes to provide a systematic bibliometric analysis of critical discussions on the link between climate change and groundwater quality in terms of chemical contamination, eutrophication, algal blooms, microbial contamination, and antibiotic resistance, and on strategic adaptation to climate change in terms of integrated groundwater management. One of the potential impacts of climate change on groundwater resources includes enhanced contamination of pollutants resulting from geogenic and anthropogenic sources. However, there has been a greater focus on the quantity and recharge potential of groundwater as impacted by climate change, and little attention has been focused on climate change impacts on groundwater quality parameters in terms of contamination. The majority of the literature focuses on the climate change induced groundwater quantity whereas this review discusses the climate change indicators from groundwater quality point of view rather than quantity. This review demonstrates that the climate-induced rising temperatures will result in increasing the groundwater temperatures approximately 1.5 to 3 degrees by end of this century and significantly impacts the groundwater quality caused by hydrogeochemical reactions. This review also highlights the climate change induced surface runoff patterns combined with wastewater discharge, and the inappropriate disposal of antibiotics causes contamination of groundwater with antibiotic-resistant bacteria, thereby posing significant risks to public health. Future groundwater quality and recharge projections require a multidisciplinary approach that integrates insights from climatology, socioeconomics, agricultural modelling, and soil sciences to comprehensively understand the complex groundwater interactions. It is suggested that further study should be performed to improve our critical understanding of the relationships between groundwater and climate to directly integrate groundwater management. The outcomes will not only contribute directly to the protection of groundwater security but also help indirectly to achieving UN Sustainable Development Goals (SDG) (SDG 6—clean water and sanitation; SDG 13—combating climate change). • High precipitation enhances the risk of microbial contamination in groundwater (GW) • Climate change event can reduce surface runoff by 21% and GW recharge by 38% • Intense wildfire accelerates mineral weathering which can raise the salinity of GW • Increase in temperature led to the changes in the biotic and abiotic processes in GW • Decrease in dissolved oxygen concentration can alter the chemical processes in GW