Spatial and temporal variations of surface water geochemistry downstream from the Pierina Gold Mine, Ancash, Peru

Changes in the geochemistry of water by the addition of heavy metals can cause many adverse environmental effects. Downstream of a gold mine, where many sulfate minerals are located, can present an opportunity for heavy metals to become dissolved in surface water. This concentration of heavy metals will then naturally attenuate as the water moves downstream. There can be large temporal variations associated with heavy metal contamination in a tropical climate. This study focuses on these temporal and spatial changes in heavy metal geochemistry of surface water downstream of the Pierina Gold Mine, in Ancash, Peru. I hypothesize that during the wet season a flush of heavy metals will be found, and that natural attenuation downstream will occur based on distance from the source of heavy metals. I found that temporal variations were not prominent. I also found that natural attenuation was controlled by the number, size and geochemistry of tributaries. Precipitation was determined to be the primary source of heavy metal mobility.