Hydrogeochemistry of sulfate-affected landscapes in Keller Peninsula, Maritime Antarctica

Keller Peninsula, located in King George Island, has a typical Maritime Antarctica climatic regime, with higher temperatures and rainfall than other areas in Continental Antarctica. The main outcropping rocks are pyritized andesites, volcaniclastics and basalts. Recent pedological investigation indicated that the presence of sulfides in Keller Peninsula accelerates the weathering process. The aim of this work was the determination of the geochemical background in water channels following geomorphological gradients in Keller Peninsula, Maritime Antarctica. We delimited and mapped all catchments in Keller Peninsula using GIS techniques and field observations. Water samples were analyzed for twenty-nine elements by ICP-OES and IEC, after the proper treatments. Eight catchments were identified as sulfide-affected, although water pH was nearly neutral. The ionic concentration in solution was high, both in non-affected and sulfide-affected catchments, with a trend of greater values in the latter, and changing downslope. Concentration values are above the range of other hydrogeochemical studies from elsewhere in Antarctica. The values of molar ratio HCO3−:(Ca + Mg)2 + and Na+:Cl− indicated the absence of carbonate-bearing rocks. Local precipitation of evaporites, as gypsum and epsomite was confirmed by the Ca2 +:SO42 − and Mg2 +:SO42 − molar ratios. The high ionic concentration in sulfide-affected areas illustrates the role of sulfate soil formation in this part of Antarctica.