Spatial Variability of Snow Chemistry of High Altitude Glaciers in the Peruvian Andes

Atmospheric contaminants become incorporated in glaciers through both wet and dry deposition. Some of this particulate matter can act as a source of contamination to glacial streams, leading to a concern for the chemical contamination to cause downstream toxicity to aquatic organisms and toxicity to people ingesting that water. Other portions of this particulate matter, including black carbon, can decrease the amount of light reflected off the snow, thereby contributing to increased rates of glacial melting. These issues are especially of concern to tropical glaciers, which are receding rapidly and are relied on heavily to provide drinking water in the dry season. A snow sampling campaign was conducted on the glaciers of seven mountains in the Cordillera Blanca mountain range in Peru during June-August, 2015 to determine concentrations of inorganic contaminants and black carbon in the upper layer of snow on high altitude glaciers (\u3e5000 m.a.s.l.). Elevation did not appear to be a factor in chemical concentrations, as there were no significant linear relationships with measured analytes and elevation, with the exception of Zn on one mountain sampled. Snow samples on two of the mountains had higher As and Pb concentrations than U.S. Environmental Protection Agency (USEPA) established water quality criteria for human health. Five metals (Al, Cd, Fe, Pb, and Zn) were found to exceed the USEPA aquatic life criteria in at least one sample. The highest concentrations of black carbon and metals were found closest to a local population center and lowest were found in areas furthest from anthropogenic influences. This study also provides supporting evidence that soil/dust is a contributing source of particulate matter but not the light absorbing fraction. An initial attempt at sourcing the particulate matter in these samples was made through an examination of analyte ratios, correlations, and principal components analysis. Multivariate analysis, including hierarchical clustering on principal components, could not explain categories based solely on concentrations of light absorbing particles or distance from the closest large city in the region. The sources of contaminants in the area appears to be complicated, and further studies would provide more insight into the source and spatial distribution of particulate matter on these tropical glaciers