Spatial and Temporal Variations of Surface Water Geochemistry
Downstream of the Pierina Gold Mine near Huaraz, Peru
Patrick M. Hoefle (’11), Dept. of Geography-Geology, Illinois State Univ.
This study focuses on the geochemical changes both spatially and
seasonally downstream of the Pierina gold mine near Huaraz, Peru. This location
provides a tropical environment with large seasonal variations in rainfall.
Sampling will take place along three streams down gradient of the mining area of
influence during the dry and rainy seasons in June 2012 and November 2012,
respectively. Onsite testing will include pH, conductivity, oxidation reduction
potential, and temperature. Samples will be analyzed for sulfate and phosphate
using an Ion Chromatograph and for heavy metals using an Intra-Coupled Plasma
Atomic Emission Spectrometer. I hypothesize that during the rainy season there
will be large increases in sulfate and heavy metals into the streams, causing a
more acidic environment. This would be due to rain acting as the leading
mechanism in dissolving the sulfide minerals at the surface. The dry season will
show lower amounts of sulfate and heavy metals because of the lack of rain
available to dissolve the minerals. I also hypothesize that the waters will naturally
attenuate from a more acidic environment to a more neutral environment as it
moves downstream and has time to react with tributaries not affected by mining
and the surrounding geology. Initial results show high levels of spatial variation.
There are dramatic changes in the onsite tests in every stream as it moves
downstream. Sample analyses are to be determined. Researching water quality
changes spatially and temporally will allow for a greater understanding to the
local communities who use this water every day.