A QUANTIFICATION OF THE EFFECTS OF ELEVATION AND ASPECT ON DEPOSITION OF AIRBORNE CONSTITUENTS AND WATER QUALITY IN AN ALPINE CRITICAL ZONE: SAN JUAN MOUNTAINS, COLORADO

The alpine critical zone is an open system which is affected by various inputs, storages, pathways, and outputs. Unfortunately, many of these processes distribute the pollutants beyond the immediate area and into the surrounding biological and anthropogenic communities. The quality of surface water within the San Juan Mountains is severely degraded from over 100 years of mining activity. However, mining may not be the only factor significantly affecting the surface waters of this high elevation environment. Studies from around the world have shown pollutants may be transported through the atmosphere and deposited in high elevation locations. Therefore, this research asks: does elevation or aspect affect the volume and rate of atmospheric deposition of pollutants? We assume atmospheric deposition occurs all over the watershed in addition to in surface water bodies. Deposition on slopes can be transported to nearby surface waters through runoff and increase the impact of the atmospheric pollutants along with residence time. Atmospheric deposition and surface water quality data were collected for aluminum, iron, manganese, nitrate, phosphate, and sulfate. In-situ water chemistry data were also collected for temperature, dissolved oxygen, pH, and specific conductance. Deposition and water quality samples were collected every fifth day representing a five day accumulation period of the above mentioned constituents. Water quality samples were collected in-stream adjacent to the deposition sample collectors. Sample locations were situated on opposite sides of Red Mountain in southern Colorado at five equal elevations providing two different aspects. Differences in atmospheric deposition and water quality at different elevations and aspects suggest there is a relationship between aspect and elevation on atmospheric pollution deposition. The degradation of water quality in the San Juan Mountains may be affected by this atmospheric deposition along with the degradation sustained from local mining activities. These results allow a better understanding of this high elevation critical zone system.