Abstract: Large quantities of deicing salts are used as a dominant way to keep road safety during the winter seasons. In many studies the effects of deicing salts on roadside soil environment, especially the potential disruption effects of deicing salts on the biochemical properties and nitrogen cycle of soil have been largely ignored. This research aimed to find correlations between the effects of 0.1%-0.6% deicing salts contaminants on microbial activity and nitrogen transformations of roadside brown soils in Shenyang. The results show a significant negative exponential relationship between the concentrations of deicing salts and soil microbial biomass C, microbial biomass N, soil basal respiration, urease and catalase activity, soil mineralization and nitrification, especially under the stress of 0.5% deicing salts per dry weight of soil. Soil microbial biomass C, soil basal respiration, urease enzyme activiy, the content of mineralizable N and nitrate N growth were inhibited significantly by the stress of 0.5% deicing salts compared with control. The C/N ratio of soil microbial biomass tended to be lower in soils with higher salinity, reflecting the bacterial dominance in microbial biomass of saline soils. Increased value of metabolic quotients (q_CO2) show that microbial community was apparently under stress. The positive relationship between microbial biomass and the content of urease enzyme, mineralizable N and nitrate N indicate that the remarkable influence of deicing salts on the activity and community structure of soil microorganisms, which could induce the decrease of nitrogen mineralization and nitrification in the soils.

Key words: deicing salts, microbial biomass, soil basal respiration, soil enzyme, mineralization, nitrification