Road salts are threatening the world’s freshwater supplies, according to a new study published by researchers at the University of Maryland.
When winter weather threatens to make travel dangerous people often use salt to help melt snow and ice. However, in a study published in the journal Biogeochemistry, researchers have warned that introducing salt into the environment releases toxic chemicals that pose a serious threat to our freshwater supply and to human health.
The researchers compared data and reviewed studies from freshwater monitoring stations across the world and found that there is a general increase in chloride concentrations on a global scale – chloride is the common element in many different types of salts.
Changes in the chloride levels call allow invasive, more salt-tolerant species to take over a stream.
The chemicals released by the salts can also change the microbes in soil and water, and because microbes are responsible for the decay and replenishment of nutrients in an ecosystem, that shift can lead to even more changes in the release of salts, nutrients and heavy metals into the environment.
Based on these findings, the researchers have said that management strategies must evaluate salt contributions from different sources on a watershed-ecosystem level and prioritise regulation accordingly.
Kaushal, lead author of the study said: ‘We used to think that once we added salt to the roads in winter it gets washed away, but we have now realised that it sticks around. Now we’re looking into both the acute exposure risks and the long-term health, environmental, and infrastructure risks of all these chemical cocktails that result from adding salts to the environment.
‘This is becoming one of the most serious threats to our freshwater supply.
‘Ultimately, we need regulation at the higher levels, and we’re still lacking adequate protection of local jurisdictions and water supplies.
‘We have made dramatic improvements to acid rain and air quality, and we’re trying to address climate change this way. What we need here is a much better understanding of the complicated effects of added salts and regulations based on that. This can allow us to avert a really difficult future for freshwater supplies.’
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