The effect of de-icing roads with salt on the environment in Krakow (Poland)

The de-icing of roads and streets in the winter season is a necessity in many European countries, where the mean day temperature drops below 0°C for long periods. Among the many chemicals used for winter road maintenance, the most popular in Poland is sodium chloride in various forms and mixtures, due to its relatively low price and availability. This agent, however, contributes to the increase of salinity in the soil environment and may lead to disturbances in soil properties and premature plant necrosis. The impact of the usage of chloride salts on the soil environment was researched in Krakow’s city centre by means of the examination of soil samples collected prior to the de-icing season (November) and afterwards (February) as well as snow samples taken in February. A general deterioration of the examined parameters (pH, conductivity, chloride concentrations, carbonate concentrations) was observed after the winter season, but still the results for most samples did not pose a serious threat to the soil environment or plants. This was mainly the result of the fact that the winter seasons in European countries have become increasingly mild and warm, which contributes to decreased usage of chloride salts. However, the state of soils in the Main Square was disturbing, as demonstrated by the clearly elevated chemical parameters of samples, despite a ban on the use of salt in this area. These results indicate the most probable reason for the withering of trees growing there, leading to them being frequently replaced.