What melts ice in sugar

WINTER SERVICE: The sugar doesn't do it

WINTER SERVICE: The sugar doesn't do it

Thousands of tons of de-icing salt are scattered on the roads in Eastern Switzerland every year. The harmful effects of salt are well known - but there are hardly any alternatives.

Christina Klein

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The winter services in Eastern Switzerland have been working at full speed for weeks. This winter, the canton of St. Gallen had already consumed a third of its salt resources - around 3,000 tons - estimates Titus Tobler from the St. Gallen Road Inspectorate. Around 2000 tons have already been used in Thurgau and Appenzell Ausserrhoden, and 200 tons in Innerrhoden. This amount corresponds roughly to the usual consumption of road salt. There is no risk of it going out. As a rule, sodium chloride, conventional table salt, is used for the streets. It ensures that the ice cannot continue to form on the streets and slowly dissolves. Only this dry salt is spread in Appenzell Innerrhoden.

If brine, a mixture of water and salt, is added to the solid salt, moist salt is created. It is easier to spread and sticks better to the ground. This salt is used in St. Gallen, Appenzell Ausserrhoden and in Thurgau. There is also the option of adding other chemical thawing agents to the salt to increase the effect. If the temperatures become too low, however, the ice can hardly be melted. The winter service can then fall back on gravel, for example. The small stones counteract the sliding, but do not dissolve the ice - only the de-icing salt can do that.

The salt is dangerous for pets

Using the spreading material is not problem-free. The sodium ions that remain on the roads seep into the soil and get into the groundwater. Snow that lies next to the roads and contains salt finds its way into rivers and lakes. This can increase their salt concentration, which can have negative effects on plants and animals. Pets are also affected. When walking on strewn streets, the salt can stick to the paws of the animals and cause inflammation.

Are there any more environmentally friendly ways to secure the roadways? Often grit, wood chips or gravel are used. But they have no thawing effect. In addition, there is additional work, as the materials have to be repeatedly scattered and collected again after the winter. Urea and ammonium sulphate also have a thawing effect, but these substances can lead to over-fertilization of the soil.

In the search for alternatives, test drives with sugar were carried out in Thurgau. However, the project was quickly canceled because the sticky mass clogged the spreader and was difficult to distribute, says Kurt Bitzer from the civil engineering department of the canton of Thurgau. "Probably the gentlest method at the moment would be to sprinkle only with brine." Spreading this way would be better for the environment, but it would be extremely costly. Vehicles that are twice as large would be necessary because the spreaders for the current winter service are not equipped with suitable tanks.

No better method known so far

So it stays with road salt for the time being. However, the cantons of eastern Switzerland agree: as soon as there is a better method, they want to use it. "We keep ourselves informed, but at the moment road salt is still the measure of all things," says Titus Tobler from the St. Gallen Road Inspectorate in the canton of St. Gallen. According to the Eastern Switzerland Winter Services, there have not yet been any major problems with the road salt. Although one or the other hedge immediately next to cantonal roads had died, alarming salt concentrations were not found either in the ground or in water. «The snow is removed according to precise specifications. This does not result in increased pollution of the water, ”says a representative of the Appenzell Ausserrhoden civil engineering department. “I can't say that there have never been any problems,” says Marco Paganoni from the Office for Environment and Energy St. Gallen. It could be that a smaller stream has a higher salt value than usual, but this would quickly equalize. The road salt does not pose a serious threat to the environment.