What are the two main causes of long-term pollution in the Kalamazoo River?

The correct response highlights PCBs (polychlorinated biphenyls) and oil spills as the primary contributors to long-term pollution in the Kalamazoo River. PCBs are harmful industrial chemicals that were widely used until their ban in the late 1970s due to their toxic effects on the environment and human health. They persist in the environment for long periods, accumulating in the food chain and adversely affecting aquatic life.

Oil spills are another significant factor, leading to immediate and long-lasting ecological damage. Oil can coat the riverbanks and aquatic organisms, disrupt the habitat, and cause severe harm to wildlife.

Together, these pollutants exemplify how industrial activity can lead to enduring contamination of waterways, emphasizing the need for strict environmental regulations and cleanup efforts to protect ecosystems and public health.