THE IMPACT OF CLIMATE CHANGE ON WATER QUALITY IN THE CORDILLERA BLANCA, PERU

The Cordillera Blanca, within Huascaran National Park in Ancash, Peru, is the highest elevation range in the northern Andes and contains the largest collection of tropical glaciers in the world. High alpine glaciated areas, especially those in the tropics, are extremely susceptible to minor changes in temperature. The overall warming trend of the last few decades has led to deglaciation within the Cordillera Blanca raising concerns about water quality and quantity now and in the future. Water chemistry in the Cordillera Blanca is primarily controlled by the bedrock composition of the watershed. The bedrock exposed in the Cordillera Blanca is dominantly granodiorite, which is heavily altered along a fault surface that defines the western margin of the range. The granodiorite is even more extensively altered within a re-mineralized contact zone that juxtaposes Jurassic and Creataceous marine sedimentary units on top of the granodiorite. The contact zone is located along the high spine of much of the Cordillera Blanca which was, until recently, covered by glaciers. Oxidation of freshly exposed sulfide minerals within the contact zone increases heavy metal contamination and extremely reduces pH in the Cordillera Blanca watersheds, causing issues for both humans and animals that depend on precipitation and glacial runoff from the Cordillera Blanca to live. Glacial melt is the primary source of fresh water for the heavily populated and arid western portion of Peru, so water contamination in the Cordillera Blanca is a major concern. This study presents new geologic maps and geochemistry of the sulfide rich mineralization zone in relation to the modern ice fields and glaciers to more accurately quantify the current and future water contamination hazard.