Natural contaminant threat to groundwater, drinking water, human health

More than half of the world’s population faces a looming threat to the quality and availability of their drinking water because climate change and urbanisation are expected to cause an increase in groundwater organic carbon, a new study has found.

The research, published in Nature Communications, examined the largest global dataset of 9404 published and unpublished groundwater dissolved organic carbon (DOC) concentrations from aquifers in 32 countries across six continents.

DOC is a naturally occurring component of groundwater, but the higher its concentration, the more difficult and expensive it is to make groundwater drinkable.

Lead author Dr Liza McDonough, of the Connected Waters Initiative Research Centre at UNSW, said the study forecast elevated DOC concentrations because of projected changes in temperature and rainfall rates due to climate change, as well as increased urbanisation.

“We identified groundwater DOC concentration increases of up to 45 per cent, largely because of increased temperatures in the wettest quarter of the year, for example in a number of south-eastern states in the United States. We predict increases in DOC in these locations could increase water costs for a family of four by US$134 per year,” Dr McDonough said.

“Other areas such as eastern China, India and parts of Africa already experience severe groundwater contamination issues. These may be further compounded, particularly in south-eastern China, by groundwater DOC increases associated with large predicted increases in temperature in the wettest quarter of the year by 2050.

“Generally, we expect urbanisation to increase groundwater DOC concentrations by up to 19 per cent, compared to agricultural or natural land use, likely as the result of contamination – for example, through leaking septic and sewer systems.”

Professor John Bridgeman, Pro-Vice-Chancellor for Research and Knowledge Transfer at the University of Bradford and one of the authors on the paper said: “We live in a world where climate change, population growth, urbanisation and pollution all mean that we are facing an urgent need to adapt to reductions in natural resource availability and reductions in energy consumption.

 “At the very heart of this are the availability and management of our water supplies.  Water is at the heart of the food, energy, climate, economic and human security challenges that we will face in the future.  If we don’t develop our knowledge of water availability and security, then our adaptation measures will have limited success, and so will our ability to survive.”

The research, a collaboration between UNSW, the Australian Nuclear Science and Technology Organisation (ANSTO), Southern Cross University, British Geological Survey, and the University of Bradford, found four major contributing factors to groundwater DOC levels: climate, land use, inorganic chemistry and aquifer age.

Read the full release from UNSW