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Show Chapter 2 Watershed Characteristics and Uses However, no studies have been found confirming life expectancies of fecal coliform in cold highly oxygenated water. NUTRIENTS Nutrients, specifically nitrogen and phosphorous, are essential to the growth of bacteria and plants. 10 Other trace elements such as iron ( Fe) are also required for biological growth. However, nitrogen and phosphorous are the major contributors to the production of algae. Algae in turn can cause taste and odor problems within water being used for drinking purposes. Methods for controlling algal blooms or growth include addition of Chelated copper compounds or potassium permanganate to the water, or simply controlling the nutrient loading. Nitrogen is also required in metabolic processes of microbial populations. If the water lacks sufficient nitrogen and/ or phosphorous, algae growth will be repressed. Waste waters or organic wastes are a good source of nitrogen for bacteria. NITROGEN SOURCES AND FATE Nitrogen has its origins as atmospheric nitrogen. It is incorporated into terrestrial systems through nitrogen fixing bacteria, lightening, direct conversion to ammonia, or fertilizer manufacturing processes. From there it enters the food chain where it is taken up by plants and eventually animals. Animals then discharge nitrogen in the form of urea or feces. Bacterial decomposition of the feces along with hydrolysis of the urea then convert the nitrogen to ammonia. Ammonia is then converted to nitrite and nitrate, or to nitrogen gas. Nitrate is especially soluble in water and therefore will move about freely within the aquatic system. The United States Environmental Protection Agency ( EPA) has determined that nitrate poses an acute health concern at certain levels of exposure. 11 The most common sources of nitrate in water include fertilizer, sewage, and wastes from humans and animals. Excessive levels of nitrate in drinking water may cause serious illness and sometimes death in infants less than six months of age. The EPA has set the drinking water standard at 10 mg/ 1 for nitrate to protect against the risk of these adverse effects. 12 Elevated levels of nitrates are often used as an indicator of human effects on stream water quality. Page 14 |