Carbon Dissolution Effects on pH Changes of RAMP Lakes in Northeastern Alberta, Canada

This study focuses on interpretation of hydrochemistry from 50 lakes thought to be acid sensitive, and so monitored by the Regional Aquatic Monitoring Program (RAMP) over the last two decades.  This study uses basic statistics, principal component analysis, lithological evidence, CO₂ saturation estimates, mineral equilibria and δ¹³CDIC measurements to describe and assess controls on pH
and to investigate causal factors of observed pH increase in the lakes.  New hydrological insights for the region: Our assessment provides evidence of two main geochemical processes that control pH increase, namely carbonate dissolution and organic matter uptake, the latter a particularly important component of alkalinity in low pH lakes. Lakes in all subregions show strong evidence of dissolution of marine carbonates of undetermined source, and lake water appears to be trending from CO₂ super-saturation towards atmospheric CO₂ equilibrium. This supports the hypothesis of carbonate input due to permafrost thaw via surface or groundwater pathways, but also reveals likely influence from CO₂ dissolution mechanisms related to climatic
influence on ice cover duration.