Which type of pollutant is commonly associated with urban runoff?

Urban runoff is a complex mixture of pollutants that can include nutrients, pesticides, and microplastics, among others. When it rains in urban areas, water flows over impervious surfaces like roads, parking lots, and rooftops. This runoff collects various contaminants, leading to serious water quality issues.

Nutrients, such as nitrogen and phosphorus, typically enter water bodies via urban runoff from fertilizers used in landscaping and agriculture, as well as from pet waste. These nutrients can lead to eutrophication, resulting in excessive algae growth that depletes oxygen in the water.

Pesticides are frequently used in urban and residential areas for pest control in gardens, parks, and lawns. During rainfall, these chemicals can wash away into storm drains and eventually reach local water bodies, posing risks to aquatic ecosystems.

Microplastics are small plastic particles that originate from various sources, including breakdown of larger plastic debris, synthetic fibers from clothing, and microbeads in personal care products. Urban runoff can carry these particles into waterways, where they can be ingested by marine organisms and enter food webs.

By selecting "All of the above," it recognizes that urban runoff is multifaceted and can contain a variety of pollutants, each contributing to a decline in surface water quality.