Jan 15, 2022 23:00:00

It turns out that the snow-melting agent is causing the salinity of the lake to rise sharply.

In snowy areas, snow melting agents using sodium chloride or calcium chloride are used to melt the snow that has accumulated on the roads and to prevent the melted water from freezing. However, the case when the salts derived from snow melting agent flows into the ponds and lakes of fresh water salinity of the water rises, with a fifth of the area in the 'World Lake Michigan salinity of soaring in the past 40 years Is reported. '

Tributary chloride loading into Lake Michigan --Dugan ---- Limnology and Oceanography Letters --Wiley Online Library
https://aslopubs.onlinelibrary.wiley.com/doi/10.1002/lol2.10228

Study finds that not even the largest lakes in the world are safe from salt
https://phys.org/news/2021-12-largest-lakes-world-safe-salt.html

The Great Lakes in North America make up about 20% of the freshwater available worldwide, and water systems, including tributaries, are of great importance to people living on the North American continent. However, in recent years, the salinity of the Great Lakes has been gradually increasing due to the influence of the snow melting agent used to melt the snow on the road.

Researchers at the University of Wisconsin-Madison and Michigan State University have analyzed the amount of salt carried from 234 different tributaries from major rivers to smaller rivers in Lake Michigan, one of the Great Lakes. Combining historical water quality data with computer models, it was found that these tributaries carry more than 1 million tons of chloride to Lake Michigan each year.

Due to this effect, the salinity of Lake Michigan, which was 1 to 2 milligrams per liter in the 1800s, has risen to nearly 15 milligrams per liter at the time of writing the article. 'We found that even large lakes are not immune to human pollution,' said Hillary Dugan, associate professor at the University of Wisconsin-Madison, the lead author of the paper. In addition, nearly half of the increase in salinity has occurred in the last 40 years, and it is expected that salinity will continue to increase at a rate of 1 milligram per liter every two to three years.

by

Rach

Although far from the '250 milligrams per liter' level, which can harm animals and plants that can only live in fresh water or become unusable as drinking water, this increase in salinity is a problem. 'Because the creatures that live in freshwater lakes have evolved to thrive in freshwater conditions, humans are stressing these creatures and may be pushing them into areas far from freshwater.' Dugan points out.

On the other hand, Lake Erie and Lake Ontario, which occupy one of the Great Lakes like Lake Michigan, have been found to have significantly reduced salinity as a result of restricting pollution around them from the 1970s based on the Clean Water Law. .. From this, Dugan said, 'If you pay attention to salt damage, you can fix this problem.'

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Paladin27

To solve the problem of increased salinity, it is important to know 'where is the chloride flowing into the lake?'. To investigate this point, the research team investigated a 'water sample of a tributary of Lake Michigan' collected by co-author Rob Mooney in another study.

When analyzed together with past water quality measurements, it was found that the factor most closely related to the amount of chloride flowing into the tributaries is 'the size of the paved ground in the basin.' The tributary with the highest salinity was found to be the tributary that carries rainwater and snowmelt to Lake Michigan from near General Mitchell International Airport in Milwaukee, Wisconsin.

However, Mooney points out that the salinity of the tributaries is only part of the problem, and that 'the amount of water flowing from the tributaries into the lake' is also an important factor. In fact, although Lake Michigan has about 300 tributaries, more than 70% of the chloride that flows into the lake comes from only five tributaries. Although these tributaries do not necessarily have high salinity, they are said to have a large total influx of chloride simply because of the large amount of water.

Mooney points out that the salinity of tributaries is not always proportional to the total inflow of chloride, which poses a difficult problem for policy makers. 'Although the largest tributaries are the ones that flush the lake with the most chloride, salinity itself is far below potentially problematic concentrations and is not necessarily a priority for chloride management, while small tributaries are less. It doesn't supply a lot of chloride, but it's getting a lot of attention because of its very high salinity, which means there's a mismatch in which tributary chloride management is prioritized. ' increase.

Whatever decision the policymaker makes, the only way to solve the problem is to 'reduce the amount of chloride used in the surrounding area.' Dugan said that municipalities and states around the Great Lakes have already updated their winter road development plans and are looking to technologies to reduce salt usage, which could lead to lower salinity. Insisted that there is.