• Energy Research

Rapid urban growth is increasing demand for potable groundwater. Dissolved organic carbon (DOC) is a major control of groundwater potability and treatment costs. We hypothesize that climate change and urbanization will not only decrease groundwater availability, but also its quality. Here, we summarize global groundwater DOC data (n = 6781) to identify its drivers and predict future changes. Our analysis of 2916 data revealed climate, dissolved inorganic ions and land use explain 31% of DOC variability, whilst aquifer age accounted for an additional 16%. Urban groundwaters were ~19% more enriched in DOC than natural or agricultural lands. We identify hotspots in the United States associated with a groundwater DOC increase of 45% by 2050, which could increase household water costs in some key regions such as Nevada, Georgia and South Carolina. Climate change will make groundwater increasingly difficult and expensive to treat, requiring more efficient and cost-effective methods for groundwater treatment in the future.

AbstractClimate change and urbanization can increase pressures on groundwater resources, but little is known about how groundwater quality will change. Here, we use a global synthesis (n = 9,404) to reveal the drivers of dissolved organic carbon (DOC), which is an important component of water chemistry and substrate for microorganisms that control biogeochemical reactions. Dissolved inorganic chemistry, local climate and land use explained ~ 31% of observed variability in groundwater DOC, whilst aquifer age explained an additional 16%. We identify a 19% increase in DOC associated with urban land cover. We predict major groundwater DOC increases following changes in precipitation and temperature in key areas relying on groundwater. Climate change and conversion of natural or agricultural areas to urban areas will decrease groundwater quality and increase water treatment costs, compounding existing constraints on groundwater resources.