River Pollution


Indicators of river pollution falls under 3 categories that is chemical, physical and microbiological indicators.

            Chemical/Physical Indicators Includes

Available oxygen: low levels of oxygen results from the introduction of organic waste pollution which increases the rate of entrophication and decrease the suitability for aquatic animal’s life.

pH: is a unit that expresses the strength of a solution based on its acidic or basic properties.  Pollution from burning fossil fuels increases the amounts of sulfur and nitrogen oxides introduced into the water thereby increasing the overall acidity. Turbidity, the increased opaqueness of a river is caused by increased sediment which negatively affects many aquatic organisms.

Heavy metal: industrial effluents are major sources of heavy metals and aquatic environments are extremely sensitive to even the smallest concentrations of these materials.  The presence of these metals in the sediments, indicates pollution

Nutrients: additional nutrients, such as phosphorus and nitrogen are indicators of river pollution which are added to streams by many avenues, but primarily through human sewage, animal waste, fertilizers and erosion.  The physical indicators are odor, taste, colour texture etc.  These aesthetics and taste of the water and may complicate the removal of microbial pathogens

            Microbiological Indicators

Presence of faecal coliforms are the principle indicators of a polluted river.  Alternate indicators for surface waters have been suggested, including, clostridium perfringes, enterococci, Bifido bacterium spp, Bacteroides fragilis, coliphages and enteric viruses.  Faecal coliforms are classified as Gram-negative rod-shaped bacteria while enterococci are Gram-positive coccoid bacteria.

A wide range of viva, bacteria and protozoan diseases result from the contamination of water with human and other animal fecal water.  Although many of these pathogens can be detected directly, environmental microbiologists have generally used indicator organisms as an index of possible water contamination by human pathogens .Major examples of this indicator organisms are Escherichia coli, Enterobacter aerogenes and Klebsiella pneumoniae.

  Sources And Causes of River Sediments Pollution

There are many specific causes of water pollution but before i list the toppers, its important to understand two broad categories.

Point source: occurs when harmful substances are emitted directly into a body of water.  It also refers to contaminants that enter a water way through a discrete “point source”.  Example of this category include discharges from a waste water treatment plant, out falls from a factory, leaking underground tanks

Non point source: delivers pollutants indirectly through or environmental change.  It can be referred to contamination that does not originate from a single discrete source.  Non-point source pollution is often a cumulative effect of small amount of contaminants gathered from a large area.  Nutrient runoff in storm, water from sheet flow over an agricultural field or metals and hydrocarbons from an area with high impervious surfaces are examples of non-point source pollution.

Specific categories of river pollution causes categorized sources of water pollution into three, namely: municipal source, industrial source and agricultural source.

Municipal Source

Municipal water pollution consist of waste water from homes and commercial establishments.  For many years, the main goal of treating municipal waste water was simply to reduce its content of suspended solids, oxygen-demanding materials, dissolved inorganic compounds and harmful bacteria.

 Pollutants from municipal sources include:

Sewage: Sewage is the term used for wastewater that often contains faeces, urine and laundry waste.  In developing countries, an estimated 90% of waste water is discharged directly into rivers and streams without treatment.  There are billions of people on earth, so treating sewage is a big priority.

In the US, 850 billion gallons of raw sewage are sent into US Rivers, lakes and bays every year by leaking sewer systems and inadequate sewer/storm systems that overflow during heavy rains.  Leaking septic tanks and other source of sewage can cause ground water crude oil spills may cause damage to the environment in many ways.  In water, oil film floating on the water surface could prevent natural aeration leading to the death of fresh water or marine life.  Fish may ingest spilled oil or other food materials impregnated with oil.  Such fish have been observed to be unpalatable.

Land-based petroleum pollution is carried into water ways by rainwater runoff. This includes fluid from cars and trucks, dribbles of gasoline spilled onto industrial machinery.  Transportation of oil from one locality to the other through boat is one of the non-spill sources of oil pollution in water.

Compounds from Mining Process: The mining process exposed heavy metals and sulfur compounds that were previously locked away in the earth.  Rainwater leaches compounds out of the exposed earth, resulting in acid mine drainage and heavy metal pollution that can continue long after the operations have ceased.

The action of rain water on piles of mining waste (tailings) transfer pollution to freshwater supplies.  In the case of gold mining, cyanide is intentionally poured on piles of mined rock when performing heap method of leaching. 

Plastic: Plastic and other plastic-like substances (such as nylon from fishing nets and lines) can entangle fish, sea turtles and marine mammals causing pain, injury and even death.  Plastic that has broken down into micro particles is now being ingested by tiny marine organism and is moving up the marine food chain.  Sea creatures that are killed by plastic readily decompose.  The plastic packaging takes 400 years to degrade.

Litter: Dumping of litter in the river can cause huge problems.  Littered items can get caught in marine animals and may result in death.  Different items take different lengths of time to degrade in water:

.   Cardboard takes 2 weeks to degrade

.  Newspaper takes 6 weeks to degrade

.  Photo degradable packaging takes 6 weeks to degrade

. Foam takes 50 years to degrade

.  Styrofoam takes 80 years to degrade

.  Aluminum takes 200 years to degrade

. Glass takes so long to degrade, that the exact time is not known. 

            Agricultural Source

Chemicals or substances used in agricultural practices are part of the large group that makes up water sediment pollutants.  Pollutants from agricultural sources includes:

Pesticides: Pesticides that get applied to farm fields roadsides and homeowners lawn runoff into local streams and rivers contaminating the freshwater that fish swim in and the water we humans drink.  Its tempting to think this is mostly a farming problem because home owners apply even more chemical to their loans than farms do to their fields.

Many compilations of pesticides exist.  Classification of pesticides may be based on structural similarity (e.g. Organochlorines, carbamates and pyrethroids) or by function insecticides, herbicides and fungicides, nematicide, bactericides, rodenticides

Fertilizers:  Many causes of pollution including sewage, manure and chemical fertilizers contain nutrients such as nitrates and phosphates.  Deposition of atmospheric nitrogen (from nitrogen oxides) also causes nutrient type water pollution.

In excess level, nutrients over stimulate the growth of aquatic plants and algae.  Excessive growth of these types of organisms clogs our water bodies and blocks light to deeper water while the organisms are alive, when the organisms die they use up dissolved oxygen as the decompose which leads to a condition known as eutrophication.  Eutrophication is when the environment becomes enriched with nutrients. This can be a problem in marine habitats such as lakes as it can cause algal blooms.

Apart from these 3 major causes of pollution, there are also pollution due to global warming and those due to atmospheric deposition.

            Industrial Source

Industry is a huge source of water pollution, it provides pollutants that are extremely harmful to people and the environment.  Many industrial facilities use freshwater to carry away waste from the plant and into rivers, lakes and oceans Pollutants from industrial sources include:

Oil, Gasoline Additives: The river bodies are polluted by oil on a daily basis from oil spills, run-offs and dumping.