A multi-parameter hydrochemical characterization of proglacial runoff, Cordillera Blanca, Peru P. Burns1, B. Mark1, and J. McKenzie2 1Department of Geography, The Ohio State University, 1036 Derby Hall, 154 North Oval Mall, Columbus, OH 43210-1361, USA 2Earth and Planetary Science, McGill University, 3450 University Street, Montreal, PQ H3A 2A7, Canada
Abstract. The Cordillera Blanca, located in the central Peruvian Andes, is the most
glacierized mountain range in the tropics. The study objective is to
determine the spatial and topographic controls on geochemical and isotopic
parameters in the Quilcayhuanca drainage basin. During the dry season of
July 2009, surface water and groundwater samples were collected from the
proglacial zone of the 90 km2 Quilcayhuanca basin which is 20%
glacierized. The basin water samples (n = 25) were analyzed for pH,
conductivity, major cations (Ca, Mg, Na, K, Fe(II)), major anions (F, Cl,
SO4), nutrients (total N, total P, and Si), and stable isotopes of water
(δ18O, δ2H). The valley's surface water is acidic
(pH 3–4) and is dominated by Ca2+, Mg2+, and SO42−,
the last of which is likely due to pyrite oxidation. Total P and total N show no
trend with elevation down valley, while Si generally increases with
decreasing elevation. Groundwater samples are differentiated from surface
water samples by lower pH, specific conductance, and total P and higher
Na+, K+, HCO3−, Si, and δ18O.
A two-component mixing model indicates that discharge from the watershed is
approximately two-thirds surface water (mostly glacier melt) and one-third
groundwater. The results were compared to data from the Rio Santa and
indicate that this trend may persist at the regional scale.
Citation: Burns, P., Mark, B., and McKenzie, J.: A multi-parameter hydrochemical characterization of proglacial runoff, Cordillera Blanca, Peru, The Cryosphere Discuss., 5, 2483-2521, doi:10.5194/tcd-5-2483-2011, 2011.