ASSESSING TRAFFIC-RELATED SULFUR IN SOILS ALONG THE MANALI-LEH HIGHWAY, NORTHWESTERN HIMALAYA, INDIA

Most studies on elemental concentrations of roadside soils have been carried out in areas where petrol is the main automobile fuel used. However, the majority of vehicles in India run on diesel rather than on petrol (7:1). Diesel exhaust emits sulfur compounds, mainly in the form of sulfides and sulfates. Sulfur emitted from vehicles settles in roadside soil and may provide a means of assessing anthropogenic impacts in a particular area. The Indian Himalaya present a perfect natural laboratory to assess the influence of vehicular pollution on the environment. Until relatively recently, communities within these mountains were isolated from the effects of urbanization. However, since the late 1970s, the Manali-Leh Highway has opened up 480 km of high altitude terrain to vehicular traffic. We measured the total sulfur content of soils from four sites along the Manali-Leh Highway using an ELTRA C-S 2000 total carbon and sulfur analyzer. At each site, we analyzed samples at incremental depths and distances from the highway. We find elevated sulfur content in soils less than 10 m from the edge of the road, which implies that vehicle exhaust is responsible. Because sulfur compounds can result in soil acidification (lower pH) and reduced microbial activities, it will be important to monitor if local vegetation and animal communities are affected by elevated sulfur levels along the highway.