Fresh water is turning saltier, flags study

Freshwater salinization can poison drinking water and increase chloride concentrations in it over time, the study underlines

By Kiran Pandey
Published: Friday 16 April 2021
Passaic river in New Jersey has turned saltier in 30 years. Photo: Wikipedia

Introducing salt into the environment — for de-icing roads, fertilising farmlands and other purposes — releases toxic chemicals that pose a threat to freshwater supply system.

This is known as freshwater salinization syndrome (FSS) or the effects of introduced salts can poison drinking water and increase chloride concentrations over time, according to a recent study published in journal Biogeochemistry.

It was carried out by researchers of University of Maryland.

The research claimed that an increase in concentration of chloride on a global scale: Passaic river in New Jersey has turned saltier in 30 years.

According to the research, FSS is caused by:

  • Road salts
  • Human-accelerated weathering of infrastructure, rocks and soils
  • Sea-level rise and saltwater intrusion
  • Evaporative concentration of salt ions from hydrologic modifications and climate
  • Disturbance of vegetation and local groundwater hydrology

A salty future  

Groundwater has been salinised by road salts over 100 years in the United States. Salt can be retained in watersheds over time in soils and groundwater, which drives the long-term increasing trends over all seasons.

Even if the use of road salt use is brought down, salt ions will not be flushed out for decades, and leave a strong legacy effect of road salts on ecosystems.

A previous study from University of Maryland researchers and published in the Proceedings of the National Academy of Sciences in 2018 looked at data drawn from 232 US Geological Survey monitoring sites for the past 50 years.

It showed that a third of the streams and rivers there got saltier over the past 25 years.

Up to 220 million people globally are at risk of exposure to elevated levels of arsenic in groundwater, which can also be mobilised by saltwater intrusion primarily in Asia. The study noted the risks of exposure to co-occurring, multiple heavy metals in drinking water in developing countries.

More than 57 per cent of India’s groundwater was contaminated with nitrate, fluoride and arsenic, according to an analysis of the government data in the State of India’s Environment in Figures, 2020.

Groundwater in at least 249 districts in 18 states and Union territories was found to be saline, according to the SOE in figures. Groundwater was unfit for consumption since it affects the digestive system, raises blood pressure and hypertension. .

Saline water incursion forced many farmers to shift to cities for work in Sathankulam block in Tamil Nadu’s Thoothukudi district in India. Use of groundwater for farming led to salt water incursion and a drop in groundwater. Not many alternatives, however, are available for drinking water, the study stated.

Surface waters are also at risk from FSS from oil and gas extraction and other forms of resource extraction, researchers said.

They found decreasing trends in nutrient concentrations in rivers due to regulations, but increasing trends in salinisation due to lack of adequate management and regulations

More work is needed to examine the extent of FSS induced by resource extraction and groundwater reserves, the study said.

Approximately 70 per cent of the Earth is covered by water; only about 2.5 per cent of that is fresh water.

Undermining this problem may entail that freshwater would not be as ‘fresh’ or have the same desired chemical, biological and physical properties, and provide the same ecosystem services as in previous decades.

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