AN ASSESSMENT OF THE EFFECTS OF ELEVATION AND ASPECT ON DEPOSITION OF AIRBORNE POLLUTION AND WATER QUALITY IN AN ALPINE CRITICAL ZONE: SAN JUAN MOUNTAINS, COLORADO, USA

The alpine critical zone 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. Years of mining and improper disposal of the tailings and acid mine drainage have degraded the quality of surface water within the San Juan Mountains. However, mining may not be the only factor significantly affecting the surface water quality in this high elevation ecosystem. As a high elevation system, this area is a fragile ecosystem with inputs ranging from local mining to atmospheric transport and deposition. Studies from around the world have shown atmospheric transport and deposition affect high elevation systems. One can ask: does elevation or aspect affect the volume and rate of atmospheric deposition of pollutants? We assume that these pollutants are deposited on the slopes as well as in streams, lakes, and ponds. Deposition on the slopes can be transported to water bodies and increase the impact of the atmospheric pollutants along with residence time. Atmospheric deposition data were collected for Aluminum, Iron, Manganese, Total Nitrogen, Total Phosphorous, and Total Sulfur. Water chemistry data were collected for the same constituents as the atmospheric deposition, including temperature, dissolved oxygen, pH, and specific conductance. Dry deposition samples were collected on filter paper; wet deposition samples were collected using rain collection containers and measured using rain gauges. Water quality samples were collected in-stream adjacent to the deposition sample collectors. Sample locations were situated on opposite sides of Red Mountain at five equal elevations on each side providing two different aspects. The north side is drained by the Uncompaghre River and the south side is drained by the Animas River. 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 and water quality in addition to the degradation incurred from mining activities. These results facilitate a better understanding of this critical zone system.