Arrange the following sequential events that occur in a freshwater ecosystem impacted by acid mine drainage pollution, starting from the initial environmental disruption to the final ecological consequence.
- 1Mining operations expose iron pyrite minerals to atmospheric oxygen and moisture, generating acidic runoff rich in sulfuric acid.
- 2The steep decline in water pH mobilizes bound heavy metals from bottom sediments into toxic, soluble ionic forms.
- 3Dissolved metal ions and high acidity disrupt ion transport across fish gill membranes, impairing gas exchange.
- 4Widespread mortality of macroinvertebrates and fish leads to the collapse of higher trophic levels in the aquatic food web.
Answer
The correct sequence starts with the chemical generation of sulfuric acid runoff from exposed iron pyrite, followed by the acid-driven leaching of heavy metals from sediment into water, leading to respiratory and osmoregulatory damage to fish gills, and culminating in ecological collapse across higher trophic levels.
Acid mine drainage begins when sulfide minerals like iron pyrite are exposed to air and water during mining, releasing sulfuric acid. The resulting low pH dissolves heavy metals from sediments, making them toxic to organisms by damaging gill membranes and disrupting respiration. This mortality ultimately leads to the collapse of the aquatic food web.
Step-by-Step Solution
Key Concept
Acid Mine Drainage Cascade