Essay: Algal Broom, eutrpophication, fish kills.
Water pollution is a major problem in the global context. It has been suggested that it is the leading worldwide cause of deaths and diseases, and that it accounts for the deaths of more than 14,000 people daily. In addition to the acute problems of water pollution in developing countries, industrialized countries continue to struggle with pollution problems as well. In the most recent national report on water quality in the United States, 45 percent of assessed stream miles, 47 percent of assessed lake acres, and 32 percent of assessed bay and estuarine square miles were classified as polluted.[3] Over the last decades, human developed their living standards but the side effect of these anthropological impacts results several environmental hazards. One of the most important of them is eutrophication.
Eutropication arises mainly from water pollution, which is the contamination of water bodies such as lakes, rivers, oceans, and groundwater caused by human activities, which can be harmful to organisms and plants that live in these water bodies. It occurs when pollutants are discharged directly into water bodies without treating it first.
Describing scientifically, eutrophication is used to indicate the artificial nutrient enrichment of an aquatic system, regardless of its initial status. This excess nutrient comes from many sources. Some of the major sources are discharge from Agricultural land, factory, mines and houses.
The contamination of water can be specified as non-point source pollution and point source pollution.
Point source pollution:
Point source pollution refers to contaminants that enter a waterway through a discrete conveyance, such as a pipe or ditch. Examples of sources in this category include discharges from a sewage treatment plant, a factory, or a city storm drain.
Non-point source pollution:
Non-point source (NPS) pollution refers to diffuse contamination that does not originate from a single discrete source. NPS pollution is often a cumulative effect of small amounts of contaminants gathered from a large area. Nutrient runoff in storm water from "sheet flow" over an agricultural field or a forest are sometimes cited as examples of NPS pollution.
Contaminated stormwater washed off of parking lots, roads and highways, called urban runoff, is sometimes included under the category of NPS pollution. However, this runoff is typically channeled into storm drain systems and discharged through pipes to local surface waters, and is a point source. The CWA definition of point source was amended in 1987 to include municipal storm sewer systems, as well as industrial stormwater, such as from construction sites.
Anthropological participation in eutrophication:
Washing pipes from domestic houses are connected to the lakes. The kitchen pipe contains protein from food and detergents, which contain nitrogenous compounds such as ammonium ions, nitrate ions phosphate ions. The sewage pipes also contain urea and phosphate from human waste. Discharge from the metal factories releases toxins such as Cu, Pb and Zn accumulates. Agricultural land uses pesticides and chemical fertilizers to increase the yield of their crops. But most of the fertilizers for example, NPK contains nitrate ion, phosphate ion and potassium ions those dissolves in soil water and are leached out by rain into the lakes or rivers giving them artificial nutrient enrichment.
Contamination can be organic or in organic substances both may result in eutrophication.
The organic substances are;
Organic water pollutants include:
- Detergents
- Disinfection by-products found in chemically disinfected drinking water, such as chloroform
- Food processing waste, which can include oxygen-demanding substances, fats and grease
- Insecticides and herbicides, a huge range of organohalides and other chemical compounds
- Petroleum hydrocarbons, including fuels (gasoline, diesel fuel, jet fuels, and fuel oil) and lubricants (motor oil), and fuel combustion byproducts, from stormwater runoff[12]
- Tree and brush debris from logging operations
- Volatile organic compounds (VOCs), such as industrial solvents, from improper storage. Chlorinated solvents, which are dense non-aqueous phase liquids (DNAPLs), may fall to the bottom of reservoirs, since they don't mix well with water and are denser.
- Various chemical compounds found in personal hygiene and cosmetic products
Inorganic contaminations are:
- Acidity caused by industrial discharges (especially sulfur dioxide from power plants)
- Ammonia from food processing waste
- Chemical waste as industrial by-products
- Fertilizers containing nutrients--nitrates and phosphates--which are found in stormwater runoff from agriculture, as well as commercial and residential use[12]
- Heavy metals from motor vehicles (via urban stormwater runoff)[12] [13] and acid mine drainage
- Silt (sediment) in runoff from construction sites, logging, slash and burn practices or land clearing sites
Scientific explanation of the process and corresponding result
Excess or enrichment of nutrients in the water encourages rapid growth of algae and blue-green bacteria, resulting in a population explosion called algal broom. The rapid population explosion of algae uses up the amount of Oxygen present in the habitat resulting an Oxygen debt for the other species. Sudden increase in temperature can also be observed due to increase in metabolic activity of the algae. As the temperature increases, the solubility of Oxygen decreases. This effect can be measured by determining the level of BOD (biochemical oxygen demand) .The phase of the sudden growth may be followed by sudden mortality because the nutrient is being limited. Dead algae rise up to the surface of the water as unsightly green scum. This green scum prevents penetration of sunlight into the water hence reducing the rate of photosynthesis. Then the aerobic bacterium appears that breakdown those dead algae causing a further demand on the supply of oxygen.
Summary of the eutrophication: The demand for oxygen becomes more over the supply during algal broom so the other species get restricted amount of oxygen resulting massive death, a situation known as fish kills.
The blue-green bacteria also release some toxic substances causing disease and sometimes death to the other members (fish) of the habitat.
The algae prevent the penetration of sunlight hence reducing photosynthesis in deep water. Therefore producers such as phytoplankton can’t survive anymore which result a large impact on the upper members (primary and secondary consumers) in the food chain. In a word, the population of the water habitat diminishes leaving some harmful impacts for the human beings.
