Effects of road deicing salts on soil microorganisms

Abstract

In this study, the effects of road salting on the quality of forest soils near the road were monitored in the Krkonoše Mountains (Czech Republic). Physical, chemical properties and microbial parameters of soils were determined and the toxic potentials of soil water extracts were evaluated using the bacterial tests (Microtox and <I>Pseudomonas putida</I> growth inhibition test). Increased concentrations of Na⁺ ions (up to 100 mg/kg) and pH values up to 8 were found closer to the road. Microbial biomass and respiration activity were significantly reduced at the roadside (ANOVA; <I>P</I> < 0.05), and the metabolic quotients showed that the microbial community was apparently under stress. Large stimulation of <I>Pseudomonas putida</I> growth was determined, especially for salinized samples closest to the road. Oppositely, results showed the unsuitability of bacteria toxicity tests in such cases of pollution. Assessment of intrinsic soil microbial communities is more ecologically relevant and shows the effects that cannot be detected by bacterial toxicity tests.