Monitoring chloride migration from dust palliative applications on the Park road, Denali National Park and Preserve, Alaska: 2007 summary report
Dates
Year
2010
Citation
Roland, Carl, 2010, Monitoring chloride migration from dust palliative applications on the Park road, Denali National Park and Preserve, Alaska: 2007 summary report: National Park Service Natural Resource Program Center National Park Service: Fort Collins, Colorado, v. NPS/CAKN/NRTR—2010/384.
Summary
The National Park Service (NPS) approved the use of Calcium Chloride as a dust suppressant on the Park road after four years of research. A formal monitoring program to track the spatial and temporal movement of CaCl2 concentrations along the Park road began in 2005. Fifteen terrestrial sites and fourteen water body locations were selected to monitor the movement of chloride from the roadbed into roadside soils and surface waters. Initial results showed wide variability in chloride concentrations in soil adjacent to the roadbed, while waterbodies generally had low concentrations (ABR 2006). This report presents 2007 results for the dust palliative chloride monitoring program.During the summer of 2007, 35 applications of CaCl2 were [...]
Summary
The National Park Service (NPS) approved the use of Calcium Chloride as a dust suppressant on the Park road after four years of research. A formal monitoring program to track the spatial and temporal movement of CaCl2 concentrations along the Park road began in 2005. Fifteen terrestrial sites and fourteen water body locations were selected to monitor the movement of chloride from the roadbed into roadside soils and surface waters. Initial results showed wide variability in chloride concentrations in soil adjacent to the roadbed, while waterbodies generally had low concentrations (ABR 2006). This report presents 2007 results for the dust palliative chloride monitoring program.During the summer of 2007, 35 applications of CaCl2 were performed on the Denali Park Road. Soil pore water was collected using suction lysimeters, two at each sampling site, approximately 1 m and 10 m from the base of the road shoulder in a transect perpendicular to the roadway. Surface water samples were collected from water bodies adjacent to the road shoulder. Two primary causes for concern emerged from this years' monitoring data:1) We observed a possible increase in the zone of influence of CaCl2-derived chloride ions in the native soils adjacent to the road. Specifically, there were major increases in the soil water chloride concentrations at the 10 m stations for three lysimeter sites in the east end lysimeter stations, contributing to an apparent increase in the average chloride concentrations at 10m for the east end sites.2) As in 2006, we recorded a few potentially biologically-significant levels of soil water chloride concentration. Specifically, we observed Cl ion concentration approaching or in excess of 100 ppm in five separate lysimeter samples from 2007 – at MP 22.2, 23.4, 26.9, 28.9, and 31.2. We noted the highest concentration level yet observed for a sample taken from a 10m lysimeter station - 198 ppm at MP 22.2.Three years worth of data indicate that at least three road segments east of the Teklanika River Bridge may have roadside soils with potentially phytotoxic concentrations of chloride as a result of current levels of dust suppression treatments. If aggressive CaCl2 application continues in these areas, toxicological problems such as chlorotic tissue or whole plant death in the roadside vegetation may begin to occur. Continued monitoring will be required to determine whether chloride concentrations have reached equilibrium or are continuing to rise due to past and present dust palliative treatments.
