Toxic Pollutants Causing Freshwater Pollution

Toxic Pollutants includes substances, which are toxic to living organisms, either lethally or sub lethally. Most of these are not a natural part of aquatic ecosystem, rather, only introduced through human activities. Examples include chemical compounds from industries, pesticides, detergents, heavy metals, oil and radioactive materials.

It is estimated that every year around 300 billion kilograms of synthetic compounds from agricultural, industrial and consumer products are routed to natural freshwater.

Many industrial chemicals, metals and pesticides are toxic to aquatic animals and humans, often affecting sensitive organs and the neuroendocrine system. Moreover, many of these are responsible for developmental anomalies by interfering with the developmental processes in various types of animals and humans.

Most of these substances are non-biodegradable, thereby persisting in the environment for a long time and accumulating in the bodies of exposed animals. Their route of exposure to humans is by drinking contaminated water and/or consuming contaminated food, such as fish and shellfish.

Detergents, mainly introduced through sewage water, alter the physical characteristics of water and affect aquatic animals as well. Detergents lower the surface tension of water causing an increased uptake of other toxins by aquatic animals, exposing them to a greater risk of mortality. On the other hand, detergents themselves are directly lethal to fish by damaging their gills and by destroying the protective mucus layer on their external surface. Detergents may also kill fish eggs. Most of the detergents release phosphates upon breakdown, resulting into formation of nuisance algal blooms.

Oil is mainly considered a problem of marine waters, but many freshwater bodies also suffer from this kind of pollution due to oil spills, natural leakage of oil from rocks or from recreational activities of humans. Oil floats on the surface of water and prevents the dissolution of oxygen, a critical feature for the sustenance and productivity of an aquatic ecosystem. It also deteriorates the drinking and aesthetic qualities of water. Oil-contaminated water is detrimental for almost all forms of aquatic life from plants to fishes.

Radioactive isotopes accumulate in the food chain. They emit radiations upon decay, which cause damage to body tissues and DNA, often leading to cancer and certain developmental malformations.