Contaminants from mountaintop removal mines are making their way into watersheds and food chains. The levels of selenium found in stream biofilm are correlated with the amount of mountaintop removal mining happening upstream, according to new research from Duke University. This directly affects insects and spiders, which subsequently intake higher levels of selenium.
This study focused on the Mud River watershed in Lincoln County, West Virginia, which is downstream from the Hobet 21 coal mining complex that closed in 2015. The research found that biofilm contains 1,000 times the amount of selenium that surrounding groundwater contains. When spiders prey on insects that have eaten biofilm, they also intake dangerous levels of selenium. Because selenium can be stored in animal tissue long-term, it has the potential to negatively impact an entire food web, including fish, according to a 2014 study.
Traveling insects and spiders from polluted streams may even bring selenium into watersheds and food webs previously untouched by mountaintop removal.
These findings are relevant to other watersheds close to sites that were mined in the past, researchers note. High selenium levels linger in downstream water for “decades after the mines have closed,” according to previous research, making this a pressing issue for stream life across Appalachia.
— By Clara Weybright