Which of the following represents nonpoint-source pollution?
During heavy rains, untreated sewage spills from a treatment plant directly into a nearby river. Attendants at a service station dump used oil into a nearby stream. Waste from a pig farm pollutes a nearby stream. Fertilizers added to fields in Illinois and Iowa leach into the Mississippi River, leading to high levels of nitrogen in the water.
Nonpoint-source pollution refers to pollution that does not originate from a single, identifiable source. Instead, it comes from multiple sources or widespread areas, making it difficult to pinpoint the exact origin of the pollution.
Among the options provided, the one that represents nonpoint-source pollution is:
Fertilizers added to fields in Illinois and Iowa leach into the Mississippi River, leading to high levels of nitrogen in the water.
This is because the fertilizers are applied over a large area (the fields) and can wash into the river during rain events, making it difficult to trace the pollution back to a specific point. The other options describe point-source pollution, where the pollution comes from a specific, identifiable source.