Changes in global groundwater organic carbon driven by climate change and urbanization

Liza K Mcdonough,Andy Baker,Alan M Macdonald,Martin S Andersen,Helen Rutlidge,Jade Ward,Dan J Lapworth,Denis M O’Carroll,Phetdala Oudone,Isaac R Santos,James P R Sorensen,Karina Meredith,John Bridgeman,Daren C Gooddy

doi:10.1038/s41467-020-14946-1

Abstract

Climate 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.

Highlights

Climate change and urbanization can increase pressures on groundwater resources, but little is known about how groundwater quality will change
Since most of the health impacts caused by dissolved organic matter (DOM) are related to the formation of byproducts and depend on the concentrations of other water chemical parameters, the World Health Organization[12] and many countries including Australia[13] do not regulate total organic carbon (TOC) or dissolved organic carbon (DOC) concentrations in drinking water directly
Most groundwater DOC concentrations fall within the 0–5 mg C L−1 range, with 84.1% of samples

Summary

Introduction

Climate change and urbanization can increase pressures on groundwater resources, but little is known about how groundwater quality will change. To determine the drivers of global DOC concentrations in groundwater, we generated a linear mixed model (Supplementary Table 2) for a large dataset (n = 2196) collected by the National Water Quality Assessment (NWQA) program of the US Geological Survey (USGS)[29].

Results

Conclusion