Increased urbanisation and climate change could cause an increase in groundwater organic carbon, affecting the quality and availability of drinking water to more than half of the world’s population. A report published in Nature Communications found groundwater dissolved organic carbon (DOC) concentration increases of up to 45% due to increased temperatures in the wettest periods of the year.
The study identified four major factors contributing to higher groundwater DOC levels — climate change, land use, inorganic chemistry and aquifer age. DOC is a natural component of groundwater, but its higher concentration makes it difficult and expensive to make groundwater drinkable.
Researchers at the University of New South Wales analysed the largest dataset yet for their report, examining 9,404 published and unpublished groundwater DOC concentrations from aquifers in 32 countries across six continents.
Groundwater is the largest source of drinking water for more than half of the world’s population. DOC increases in a number of south-eastern states of the US could increase water costs for a family of four by $134 per year, a UNSW report quoted Liza McDonough, lead author of the report, as saying.
Eastern China, India and parts of Africa are already experiencing severe groundwater contamination problem. This problem may aggravate, especially in south-eastern China, because of groundwater DOC increases due to higher temperatures in the wettest months, the report said.
Urbanisation will increase groundwater DOC concentrations by almost a fifth, said 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.
The quality of ground water and its potability depend on the quantity of dissolved organic carbon that can alter water chemistry and the presence of microbes. It is estimated that more than 1,00,000 cancer cases in the US are caused by contaminants in drinking water. The largest risk in this regard is associated with the presence of disinfection by-products and arsenic, both are linked to DOC.
Water treatment using chlorination and ozonation can produce harmful by-products due to the presence of organic matter. These by-products can be genotoxic or carcinogenic.