Question

Coal Resources – Farmersburg, IN. Extracting coal in open-pit strip mines may lead to unwanted consequences. When water reacts with minerals in excavated rock, the runoff into lakes and streams contains elements that affect water quality. Check and double-click the Problem 7 placemark (also, fly over the mine and nearby reclaimed areas). What evidence from 2005 do you see that suggests possible contamination (which is much improved in present-day imagery)? Choose one: Water in the pond has an unusual red algal bloom in it. The land surrounding the pond is completely devoid of vegetation. Sediments exhibit an orange color and water in the pond has an unusual green color. Sulfur from the coal has re-precipitated as a bright yellow ring along the pond shoreline.

Answer 1

The most likely evidence from 2005 that suggests possible contamination is that the sediments exhibit an orange color and water in the pond has an unusual green color.

Orange color could indicate the presence of iron oxide (rust) which is often associated with acid mine drainage (AMD). AMD occurs when water reacts with minerals in exposed rock, like those found in coal mines, and becomes acidic. Iron-bearing minerals in the rock dissolve in the acidic water, resulting in the orange color.

Unusual green color could be a sign of excessive algal growth. Algae thrive in nutrient-rich environments, and AMD can introduce various nutrients like phosphorus and nitrogen into the water. This can lead to eutrophication, where excessive algae bloom depletes oxygen levels in the water, harming other aquatic life.