『Abstract
　It is hypothesized that episodic introductions of road salt severely disrupt the soil nitrogen cycle at a range of spatial and temporal scales. A field-scale study has confirmed impacts on the nitrogen cycle in soil, soil solution and river samples. There is evidence that ammonium-N retention on cation exchange sites has been reduced by the presence of sodium ions, and that ammonium-N has been flushed from the exchange sites. Increases in soil pH have been caused in naturally acidic uplands. These have enhanced mineralization of organic-N, especially nitrification, leading to a reduction in the mineralizable-N pool of roadside soils. There is evidence to support the hypothesis that organic matter content has been lowered over decades either through desorption or dispersal processes. Multiple drivers are identified that contribute to the disruption of nitrogen cycling processes, but their relative importance is difficult to quantify unequivocally. The influence of road salt on soil and soil solution declines with distance from the highway, but impacts on water chemistry in a local stream are still strongly evident at some distance from the road.

Keywords: Cationic displacement; Nitrogen cycle; Road salt; Sodium chloride』

1. Introduction
2. Materials and methods
　2.1. Field site
　2.2. Sample collection
　　2.2.1. Soil sampling
　　2.2.2. Soil solution sampling
　　2.2.3. Freshwater sampling
　　2.2.4. Bulk precipitation and drainage chemistry
　2.3. soil analysis
　2.4. Freshwater, precipitation, road drainage and soil solution analysis
　2.5. Statistical analysis
3. Results
　3.1. Road drainage and bulk precipitation chemistry
　3.2. Base cation and hydrogen ion occupation of the CEC
　3.3. Soil pH
　3.4. Soil extractable ammonium-N
　3.5. Soil extractable nitrate-N
　3.6. Soil loss-on ignition and C:N
　3.7. soil solution sodium
　3.8. Soil solution nitrate-N
　3.9. Soil solution ammonium-N
　3.10. Crookdale Brook
4. Discussion
5. Conclusion
Acknowledgements
References