Modeling fate and transport of sulfate and alkalinity in an acidified lake

Acid mine drainage from Contrary Creek flows into an entire arm of Lake Anna. Much of the acid inflow is neutralized by bacterial sulfate reduction in the lake sediments. We developed a simple model to track the seasonal fate and mass transport of sulfate and alkalinity along the acidified arm. The loss of sulfate from the water column was characterized by a first-order decay reaction. A gain in alkalinity due to sulfate removal was also incorporated in the model. In addition, CO₂ acidity and pH in the water column were calculated. The model was calibrated with data collected in 1983 and 1984. Model sensitivity runs were conducted to demonstrate the importance of sulfate reduction in the system.