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 urbanization are expected to cause an increase in groundwater organic carbon, a new UNSW study has found.
The research, published in Nature Communications overnight, examined the largest global dataset of 9404 published and unpublished groundwater dissolved organic carbon (DOC) concentrations from aquifers in 32 countries across six continents.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. In Australia, groundwater is widely used as the main source of drinking water for many cities and towns.
Lead author Dr. Liza McDonough, of the Connected Waters Initiative Research Centre at UNSW, said the study forecasted elevated DOC concentrations because of projected changes in temperature and rainfall due to climate change, as well as increased urbanization.
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.
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 urbanization 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." Dr. Liza McDonough, lead author
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. Health threat
Dr. McDonough said increased groundwater DOC, whether naturally occurring or due to contamination, also posed a threat to human health.
"Groundwater is Earth's largest source of freshwater and provides essential drinking water for more than 50 per cent of the world's population," she said.
"But, because most health impacts caused by DOC are related to the formation of by-products of water treatment chlorination and depend on concentrations of other water chemical parameters, the World Health Organization and many countries - including Australia - do not regulate DOC concentrations in drinking water directly." Related Stories
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