Hobbies And Interests
Agricultural Activity
Modern agriculture makes widespread use of artificial fertilizers, pesticides and herbicides. These chemicals help optimize acreage yield. However, they typically settle and accrue in topsoil. When exposed to rain, runoff carries these compounds into streams and eventually into rivers. Once in river water, fertilizers rich in synthetic nitrates promote abnormally high plant growth. This lowers oxygen content in water, killing fish and disrupting the river's ecosystem. Pesticides and herbicides further contribute to river pollution, degrading it as a supply of fresh water.
Farming
Industrial farms for pigs, chickens and cows generate enormous amounts of waste. Runoff or spillage may occur either from the animals' holding pens or from large pools where the waste is collected. Animal waste contain bacteria as well as substantial amounts of nitrogen and phosphorus. These compounds promote excessive plant growth in rivers, depleting oxygen and killing fish. Nitrogen and phosphorus may also cause adverse health effects when river water is drunk. In addition, waste from cow farms can also carry hormones and antibiotics into river water, where they contaminate the food chain.
Industrial Activity
Mining activities also have the potential to pollute rivers. This pollution comes in the form of either mineral contaminants or chemical pollution from industrial processing. For example, gold mines use cyanide to leech gold out of rock ore, and the chemical can be washed into rivers by rain. Mining also exposes waterways to minerals and heavy metals being mined, such as lead and arsenic. Logging damages rivers by allowing displaced soil to settle into rivers, increasing sediment and damaging the river's biodiversity. Acid rain stemming from atmospheric pollution alters the pH of a river, disrupting its ecosystem.
Proximity to Urban Centers
Cities are major sources of pollutants. Raw sewage may spill into waterways if treatment plants malfunction or sewage systems are overloaded by rain or floods. Common household chemicals are often dumped into sewers and drains; these can range from cleaners such as bleach to washing detergents. A large city can pollute a waterway with a wide variety of contaminants, as rains will flush a stew of bacteria, petrochemicals and animal waste into rivers through drainage systems.