posted on 2020-03-17, 21:29authored byAlexandre Guittard, Michel Baraer, Jeffrey M. McKenzie, Bryan G. Mark, Alejo C. Rapre, Jeffrey Bury, Mark Carey, Kenneth R. Young
As a result of climate warming and
glacier recession, glacierized
watersheds will experience a decrease in dry season discharge and
an increase in wet season discharge, with negative consequences for
water quality. The glacierized Rio Santa watershed in Peru provides
a unique opportunity to study these concerns, because it drains the
mountain range with the highest density of glaciers in the tropics.
The mountain range has already passed peak water due to glacier retreat,
and previous studies have reported high concentrations of dissolved
trace metals in the Rio Santa. During summer 2013, 40 sites along
the Rio Santa watershed were sampled for river bed sediments. In addition,
water samples were collected at a single location in the Rio Santa
over a period of 1 year. A sequential extraction was performed on
the sediments and analyzed for Al, As, Cd, Fe, Pb, and Zn concentrations.
Results show a chemostatic behavior of studied trace metals and present
comparable distributions of metals among phases in the Rio Santa and
its tributaries. These results suggest that at least a portion of
the surface sediment contamination from trace metals originates from
a transfer of primary particles from contaminated tributaries. In
a post peak water context, this study implies that the increase in
wet season discharge related to glaciers may represent a risk of contamination
spread associated with sediment transport enhancement.