Monday , May 17 2021

Salt roads create dangerous "chemical cocktails"


Image: Salt applied on the roads as winter decoction proved to be a significant contributor to the increased salinity in freshwater in the United States, Europe and elsewhere. New research …
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Credit: Joseph Galella / University of Maryland

A recent study led by researchers at the University of Maryland found that streams and rivers across the United States became salty and more alkaline over the past 50 years thanks to passengers, fertilizers and other salty compounds that people indirectly release into the waters. The team called this effect "Freshwater sanitary syndrome".

New research from the same UMD-led group brings global, regional and local consequences from a freshwater salinization syndrome closer. The group found that salty, alkaline fresh water can release various chemicals, including toxic metals and harmful compounds containing nitrogen, from streets and soils in drainage basins. The results further suggest that many of these chemicals travel together across basins, forming "chemical cocktails" that can have more devastating effects on drinking water supply and ecosystems, compared to individual pollutants.

The final work of the group, which includes field observations from the Washington area, DCC. and Baltimore, emphasizes the need for new and more comprehensive pollution management regulations and strategies. The research team published its findings on December 3, 2018 in the journal Philosophical Transactions of the Royal Society B..

"The bottom line of our findings is that when people add salt in the water, it also releases very dangerous collateral chemicals," said Sujai Kouchal, UMD professor of geology and chief author of the study. "It is clear that regulatory agencies need to find new ways to address these" chemical cocktails "released from salt waters, rather than looking at individual contaminants of freshwater one by one."

Salt, alkaline freshwater already known creates major problems for drinking water supply, urban infrastructure and natural ecosystems. For example, when Flint, Michigan, changed its primary water source to the River Flint in 2014, the high salt water of the river combined with chemical treatments to make corrosive water, causing leakage from water pipes and creating a well documented city the water crisis.

The latest research project by Causal and colleagues examined the effects of chemical cocktails created by salt water in more detail. The group started assessing previously published data from rivers in the United States, Europe, Canada, Russia, China and Iran, significantly expanding the geographical boundaries of researchers' previous work. Their analysis suggests that freshwater salinization syndrome could be a global phenomenon with the most consistent support that shows a constant trend of increased salt ions in both rivers in the United States and Europe. These trends look back at least 50 years, with some data reaching far enough to support the 100-year-old trend.

"In light of what we discover, I continue to be surprised by the scale and magnitude of the recent degradation of surface water on Earth," co-author Jean-Louis Lincense, president of the Kerry Ecosystems Institute and a prominent research professor at the University in Connecticut. "The formation of new chemical cocktails causes deterioration far from my expectations."

In the snowy Mid-Atlantic states and New England, road salt applied on the roads in winter is the primary cause of freshwater salination syndrome. Causal and his colleagues dived deeper into the chemical consequences of road salt, performing detailed field exploration in streams located near Washington, DC. and Baltimore.

In one observational observation, researchers took water from the Paint Branch branch near the UMD campus before, during and after a snowstorm of 2017. This aspect of the study allowed the team to find out the effects of the road salt that was washed in the flows by melted snow.

"We thought it would be interesting to look at the chemistry in an urban river through a snowstorm," says Kelsey Wood (BS 15, Geology), a graduate student of geology at UMD and a co-author of the study. "The salt concentrations during a snowstorm were surprisingly high – it was like analyzing sea water, but we did not expect such a high corresponding peak in metals."

Previous studies have shown that many salty water can compel metals – especially copper, cadmium, manganese and zinc – from underground soils and into stream water. In the creek of the Paint branch, Kaushal and his colleagues noted large amounts of copper, manganese and zinc right after the snowstorm. In a similar set of observations in Washington DC, Rock Creek, DC, the team recorded noticeable increases in cadmium, copper and zinc after other snowfall.

In another series of experiments, scientists artificially added salt in the River Gwins Falls near Baltimore to simulate what happens during a snowstorm and measure the concentration of copper in the water before, during and after the addition of salt. The data from the downstream movement showed an instantaneous jump in copper released from the accumulated, indicating a direct relationship between the salt content and the copper content in the water.

Salt ion concentrations may remain high months after storm, Causal added. This lengthens how much salt can draw metals from the soil, resulting in harmful cocktails from metals and salts transported far downstream.

"Looking at the data on water quality over several months during the winter, the salt remains high and rarely has a chance to return to the baseline before the next storm comes and more salt is put on the roads," said Kouchal, who, also has an appointment in the UMD's Earth System System Science Interdisciplinary Center. "This large salt load not only releases metals and other pollutants, but there is also evidence that the initial salt pulse releases other salts from ions from suppressions and soils, such as magnesium and potassium, which further contributes to maintaining the overall levels of salt ".

In the highly agricultural Midwest and the regions of the Central Atlantic countries, agricultural fertilizers are an important cause of freshwater salination syndrome. For further research, the research team reviewed water quality data from 26 different locations for US Geological Survey (USGS) for monitoring the rivers in these areas.

These USGS stations collect data every 15 minutes for salinity, pH and nitrate ions – a harmful by-product of agricultural fertilizers and other pollutants. These high-frequency measurements gave the research team valuable insight into real time, with several of the rivers showing a clear and almost immediate connection between the increased concentration of salinity and nitrates.

"For me, this study highlights the need for salt water to be seen as a contaminant in fresh water," says Shahan Huck (BS.S14, Physics), graduated UMD geology student and co-author of the study. "The ability of Solta to transport heavy metals like copper from sediment to water can have dangerous implications on our drinking water and can be toxic to wildlife. Our remarks suggest that some rivers are already at risk, especially here eastern United States directly on road salt applications. "


In addition to Kaushal, Wood and Huck, co-authors of UMD-related research work include geology students, Joseph Galella and Carol Morel, and graduate student of biology and science and technology Barrett Wessel. Also co-authors are also former graduates Thomas Dudi (BS, 14, MS & # 17; geology) and Ryan Utz (PhD, 10, marine estuary and environmental science).

The research paper "Romanian Chemical Cocktails" in Inland Waters is a consequence of the Freshwater Shelter Syndrome ", Sujay Kaushal, Gene Likens, Michael Pace, Shahan Haq, Kelsey Wood, Joseph Galella, Carroll Morel, Thomas Dudy, Barret Wessel, Pirko Cortelianen , Anti-Raike, Valery Skinner, Ryan Utz and Norbert Jaroski, was published on December 3, 2018 in the journal Philosophical Transactions of the Royal Society B..

This work was supported by the National Science Foundation (Rewards No. EAR-1521224, DEB-1027188 and CBET-105850). The content of this article does not reflect the views of this organization.

For a more background on the concept of chemical cocktails, please see another recent publication co-authored by Causal, Wood and Huck, "Chemicals from the Basin": the formation of new elementary combinations in anthropocene fresh waters, "Sujay Kaushal et al., Published October 22, 2018 in the journal Biogeochemistry: https: // /9R1S

Media contact: Matthew Wright, 301-405-9267, [email protected]

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