What Are the Causes and Impacts of Water Pollution - Essay Example

 Research Problem What are the causes and impacts of water pollution? Water pollution refers to the contamination of water bodies such as rivers, lakes, aquifers, oceans and ground water. It occurs when pollutants are directly or indirectly discharged into water bodies without adequate treatment to remove harmful compounds. In numerous parts of the world mainly the developing world, water pollution is a widespread menace which has profound effects on the aesthetic characteristics of the environment, the health of the consumers of the polluted water and in general the economic and social wellbeing of these areas. As a consequence, water is relatively scarce resource in numerous parts of the world. Water pollution is a major contributing factor to this scarcity of clean water to the human population. Review Water pollution has numerous causes, some of which can be avoided by promoting and implementing proper waste treatment before disposal in water bodies, proper application of fertilizers and herbicides in farms and appropriate usage of water by users in its natural state. Causes of water pollution Sewage plants Most municipalities mainly in the developing world do not have modern sewage treatment systems to optimally treat wastes collected. Moreover, the systems in place are not very efficient in the treatment of the wastewaters since most are poorly maintained and repairs are hardly affected. In addition, treatment is mainly restricted to primary and secondary treatment processes thus removing only pathogens and gross organic wastes. The water released is thus harmless to other users but laden with nutrients (Rogers 2004). Agricultural sources High nutrient fertilizers applied to agricultural lands mainly by large scale farmers are a source of pollutants causing water pollution. High levels of nitrogen and phosphorous are essential in the efficiency of these products. Therefore runoff from fertilized areas into water bodies such as rivers causes a dramatic increase in nutrient levels in the water bodies.(Jeffries & Mills 2003). Detergents Many domestic and industrial detergents contain significant levels of nutrients which are responsible for eutrophication of water bodies. An example is the cleaning activities carried out by residents living around a water body. Solid waste disposal sites Domestic and industrial solid wastes deposited in various areas contain large amounts of organic matter and heavy metals. Nutrient-rich, organo-chemical byproducts of decomposition are leached from these sites and find their way into water bodies through surface and underground flow. Industrial point sources Many industries in numerous parts of the world release effluent laden with nutrients, organic matter and heavy metals into water bodies. These components increase the nutrient content of the water causing its eutrophication. Acid rain Various manufacturing industries such as chemical, beer and tanning industries regularly release acidic substances from point sources directly into water bodies such as rivers. In addition to these sources, low PH precipitation resulting from atmospheric pollution (acid rain) is a major cause of water pollution .This has been observed as a substantial problem especially in industrialized countries (Streets & Foell 2001). Acid rain also occurs when sulfur dioxide, carbon dioxide and oxides of nitrogen emitted into the atmosphere (from sources such as fossil fuel burning, iron smelting, chemical extraction processes and motor vehicle exhaust emissions) combine with atmospheric oxygen and water to produce acids of sulfur, carbon, and nitrogen respectively (Jeffries & Mills 2003). The mining industry This is also a major contributor to the pollution of water bodies in numerous parts of the world. The pollution occurs via the acid mine drainage which lowers the pH levels of water into which the drainage takes place. The acidification process involves oxidation of pyrite (FeS2)-bearing rocks generating sulfuric acid and water soluble species of sulfur and iron. This causes acidification of water running over these rocks. Impacts of water pollution With increase in nutrient levels in the water bodies, the blue-green algae become dominant causing a concomitant reduction in water transparency. The activity of decomposers whose population rapidly increases with disposal of organic wastes into water leads to depletion of oxygen in both water and sediments. The resulting anaerobic conditions influence nutrient cycling causing the accumulation of products often to toxic levels. (Mason 2004). Sediment disposal into water bodies leads to increased turbidity causing increased light attenuation and a consequent lowering of primary productivity. Acidification of water bodies causes an influx of hydrogen ions into the aquatic system disrupting the ionic regulating mechanisms of many organisms. Heavy metals such as mercury and aluminum deposited into water bodies are toxic thus may cause deaths of aquatic organisms such as fish. Also, when fish that contain heavy metals are consumed by humans, human deaths or poisoning may occur. TABLE 1: Classes of non-point source pollution (highlighted categories refer to agricultural activities) (Source: International Joint Commission, 1974, and other sources) Agriculture Animal feedlots Irrigation Cultivation Pastures Dairy farming Orchards Aquaculture Runoff from all categories of agriculture leading to surface and groundwater pollution. In northern climates, runoff from frozen ground is a major problem, especially where manure is spread during the winter. Vegetable handling, especially washing in polluted surface waters in many developing countries, leads to contamination of food supplies. Growth of aquaculture is becoming a major polluting activity in many countries. Irrigation return flows carry salts, nutrients and pesticides. Tile drainage rapidly carries leachates such as nitrogen to surface waters. Phosphorus, nitrogen, metals, pathogens, sediment, pesticides, salt, BOD1, trace elements (e.g. selenium). Forestry Increased runoff from disturbed land. Most damaging is forest clearing for urbanization. Sediment, pesticides. Liquid waste disposal Disposal of liquid wastes from municipal wastewater effluents, sewage sludge, industrial effluents and sludges, wastewater from home septic systems; especially disposal on agricultural land, and legal or illegal dumping in watercourses. Pathogens, metals, organic compounds. Urban areas Residential Commercial Industrial Urban runoff from roofs, streets, parking lots, etc. leading to overloading of sewage plants from combined sewers, or polluted runoff routed directly to receiving waters; local industries and businesses may discharge wastes to street gutters and storm drains; street cleaning; road salting contributes to surface and groundwater pollution. Fertilizers, greases and oils, faecal matter and pathogens, organic contaminants (e.g. PAHs2 and PCBs3), heavy metals, pesticides, nutrients, sediment, salts, BOD, COD4, etc. Rural sewage systems Overloading and malfunction of septic systems leading to surface runoff and/or direct infiltration to groundwater. Phosphorus, nitrogen, pathogens (faecal matter). Transportation Roads, railways, pipelines, hydro-electric corridors, etc. Nutrients, sediment, metals, organic contaminants, pesticides (especially herbicides). Mineral extraction Runoff from mines and mine wastes, quarries, well sites. Sediment, acids, metals, oils, organic contaminants, salts (brine). Recreational land use Large variety of recreational land uses, including ski resorts, boating and marinas, campgrounds, parks; waste and "grey" water from recreational boats is a major pollutant, especially in small lakes and rivers. Hunting (lead pollution in waterfowl). Nutrients, pesticides, sediment, pathogens, heavy metals. Solid waste disposal Contamination of surface and groundwater by leachates and gases. Hazardous wastes may be disposed of through underground disposal. Nutrients, metals, pathogens, organic contaminants. Dredging Dispersion of contaminated sediments, leakage from containment areas. Metals, organic contaminants. Deep well disposal Contamination of groundwater by deep well injection of liquid wastes, especially oilfield brines and liquid industrial wastes. Salts, heavy metals, organic contaminants. Atmospheric deposition Long-range transport of atmospheric pollutants (LRTAP) and deposition of land and water surfaces. Regarded as a significant source of pesticides (from agriculture, etc.), nutrients, metals, etc., especially in pristine environments. Nutrients, metals, organic contaminants. 1 BOD =Biological Oxygen Demand 2 PAH = Polycyclic Aromatic Hydrocarbons 3 PCB = Polycyclic Chlorinated Bi-Phenyls 4 COD = Chemical Oxygen Demand Conclusion Water pollution is a huge problem bedeviling many countries and curtailing exponential growth of their economies. This presentation illustrates some of the causes and impacts of water pollution to the biotic and abiotic components of the environment. Since these impacts are majorly negative, effective water pollution management practices aiming at reducing or eliminating this menace should be developed and strictly implemented to prevent future collapse of the ecosystem. Audience questions and answers What are some of the water pollution management practices that can be implemented by municipalities and cities to minimize or eliminate water pollution? Answer: Municipalities with sanitary sewer overflows or combined sewer overflows may: Utilize green infrastructure to improve storm water management capacity throughout the system and reduce overloading of treatment. Repair and replace leaking and malfunctioning equipment. Increase the overall capacity of the sewage collection system. What measures households or industries not served by the municipal treatment plants implement to avoid causing water? Answer: They can operate private septic tanks which treat the wastewater on site and discharges into the soil. They may also send the domestic wastewater to a nearby communally owned treatment system. What are the measures that industries can put in place to ensure that the wastes they release do not cause water pollution? Answer: Install pre-treatment systems that remove the toxic components contained in conventional pollutants, toxic pollutants and non-conventional pollutants and then send the partially treated wastewater to the municipal system. Redesign manufacturing processes to reduce or eliminate pollutants. Operate privately owned complete on-site treatment systems if generating large volumes of sewage. Visual Aid Segment After a series of research on the causes and impacts of water pollution, I came across various sample findings on the same, which had been done earlier. Agricultural Sources and impacts Retrieved from: http://unplugstory.info/wp-content/uploads/2013/12/14355783-tractor-spraying-a-field-on-farm-in-spring.jpg Excessive spraying and fertilizer application on agricultural lands as exhibited above leads to accumulation of toxic chemicals and excess nutrients in the soil. These are washed away by the surface runoff and deposited in water bodies causing water and pollution. Excess nutrients in water for example cause water eutrophication as evidenced in the picture below. Retrieved From: http://ericrumble.typepad.com/blog/2011/06/investigating-the-state-of-lake-winnipegs-eutrophication-for-canadian-geographic.html Industrial sources Retrieved From: http://www.eugene-or.gov/index.aspx?NID=454 Industries and domestic homes produce a variety of wastes on daily basis. These Industrial and domestic wastes when disposed off into water bodies cause massive pollution and marine intoxication, which can be very detrimental to aquatic and marine life resulting in massive deaths. Impacts evidenced in the picture below. Retrieved From: http://www.treehugger.com/corporate-responsibility/the-price-of-chinas-pollution-and-its-environmental-catch-22.html References: David G. (2001).Environmental Management, Acid Rain in Asia. http://ericrumble.typepad.com/blog/2011/06/investigating-the-state-of-lake-winnipegs-eutrophication-for-canadian-geographic.html http://unplugstory.info/wp-content/uploads/2013/12/14355783-tractor-spraying-a-field-on-farm-in-spring.jpg http://www.eugene-or.gov/index.aspx?NID=454 http://www.treehugger.com/corporate-responsibility/the-price-of-chinas-pollution-and-its-environmental-catch-22.html Jeffries, M. & Mills D (2003), Fresh Water Ecology: Principles and Applications, London. Belhaven Press. Mason, C. (2004), Biological aspects of freshwater pollution. Longman, New York. Rogers K.H (2000), The use of Olifantsvlei for water quality improvement, Unpublished Report. Department of Botany, University of Witwatersrand. Read More