<p> Water Watch Water Quality Tests</p><p>Dissolved Oxygen (DO): Most aquatic plants and animals need oxygen to survive. Fish and many aquatic insects and crustaceans have gills to extract oxygen dissolved in the water. Most of the dissolved oxygen in water comes from the atmosphere. Waves and rapids in lakes and streams act to aerate the water. Algae and aquatic plants also contribute oxygen through photosynthesis. Dissolved oxygen is influenced by the water temperature. As with all gases, oxygen dissolves more easily in cool water than in warm water. The main factor which could cause a drop in dissolved oxygen is the presence of organic matter in the water. Organic matter is anything that once was living, such as food, leaves, waste products, etc. Organic waste can enter lakes and streams from sewage, food processing industries, or agricultural runoff. </p><p>NOTES: ______</p><p>______</p><p>Biochemical Oxygen Demand (BOD): When organic matter decomposes, it is broken down or oxidized by aerobic bacteria. Biochemical Oxygen Demand is a measure of the quantity of dissolved oxygen used by bacteria during the decomposition. It basically involves performing a dissolved oxygen test. Then an identical sample of river water is held in the dark for five days, and another dissolved oxygen test is done. The difference in DO levels is the biochemical oxygen demand. </p><p>NOTES: ______</p><p>______pH: + - Water (H2O) contains both hydrogen (H ) ions and hydroxide (OH ) ions. pH measures the concentration of hydrogen ions in water, on a scale from 0 to 14. Pure water has an equal number of hydrogen and hydroxide ions and has a pH of 7. Acids are solutions with more hydrogen ions than hydroxide ions and have a pH of less than 7. The lower the pH, the stronger the acid. Bases, or alkaline solutions have more hydroxide ions than hydrogen ions and have a pH of more than 7. Again, the higher the pH, the stronger the base. Most lakes and streams have a pH of between 6.5 and 8.5. Most organisms (except for some types of bacteria) cannot survive if the pH is greater than 9 or less than 4.5. The pH of some lakes and rivers can be lowered by “acid rains.” When the atmosphere has nitrogen and sulfur oxides in it – from the burning of fossil fuels such as gasoline and coal – moisture combines with those chemicals to produce nitric and sulfuric acids. When this moisture falls as acid rain, it can lower the pH of the lakes and rivers below. NOTES: ______</p><p>______</p><p>Nitrates: Nitrogen is an element needed by all plants and animals to produce protein. Most of the air we breathe (79%) is nitrogen. Certain types of algae and bacteria can convert this nitrogen into nitrate ions, which are picked up and used by plants. Since nitrates act as a plant nutrient, they can cause increased growth of algae in lakes and streams. This can eventually lead to a condition called “eutrophication.” Nitrates can enter lakes and streams from sewage – inadequate treatment plants or septic systems – or fertilizers or runoff from cattle farms. Drinking water high in nitrates can cause a condition called methemoglobinemia (“blue baby syndrome”).</p><p>NOTES: ______</p><p>______</p><p>Phosphates: Phosphorus is another element essential for life. It occurs in lakes and streams as phosphate ions, and is usually present in very low concentrations. Phosphates come from several sources including sewage, soil erosion, fertilizers and detergents. As with nitrates, phosphates are also plant nutrients and can promote the growth of algae (eutrophication) if they are present in high concentrations.</p><p>NOTES: ______</p><p>______</p><p>Total Solids: Total solids include both dissolved substances, and suspended substances in water. Suspended solids can include silt, algae or organic matter. Dissolved materials may include a variety of ions including iron, nitrogen, sulfur, phosphorus and calcium. While each of these are necessary building blocks for life, excessively high levels of solids can reduce water quality. Total solids are measured by carefully weighing an empty beaker, filling it with exactly 100 ml of river water, evaporating the water and weighing the “residue” left in the beaker.</p><p>NOTES: ______</p><p>______Turbidity: Turbidity is a measure of the relative cloudiness of the water. High turbidity can be caused by soil erosion, urban runoff, or the growth of algae. As Turbidity increases, water generally increases in temperature and loses its ability to hold oxygen. Suspended particles can also clog the gills of aquatic organisms and reduce their growth rates. </p><p>NOTES: ______</p><p>______</p><p>Temperature: Water temperature affects many of a river’s characteristics. For example, temperature affects the amount of oxygen that can be dissolved; the rate of photosynthesis by plants; and the metabolic rates of aquatic organisms. Humans can influence water temperature in a number of ways. Certain industries, such as electric power plants, use surface water for cooling, returning warmer water to the river or lake it came from. When trees are cut near the shore, direct sunlight caused by a lack of shade can warm the river. Erosion also clouds the water, causing it to more easily absorb the sun’s rays. The temperature test measures the change in a river’s temperature between two points, one mile apart.</p><p>NOTES: ______</p><p>______</p><p>Fecal Coliform Fecal coliform bacteria are found in the wastes of all warm-blooded animals. They can enter rivers through direct discharge from animals, agricultural and storm runoff carrying animal wastes, or contamination from human sewage. Although fecal coliform are not pathogenic themselves, their presence can indicate the presence of disease-causing bacteria, viruses, or protozoans. </p><p>NOTES: ______</p><p>______</p><p>Benthic Macroinvertebrates The term “benthic” means bottom-dwelling. Macroinvertebrates are animals without backbones that can be seen with the unaided eye. Many benthic macroinvertebrates are aquatic insects – in the immature larval or nymph form. They may also be crustaceans, worms or mollusks. Benthic macroinvertebrates are indicators of water quality in basically two ways. First, a high level of diversity generally indicates high water quality. Second, certain organisms are intolerant of pollution. They can only survive in clean water and are therefore “indicators” of high water quality.</p><p>NOTES: ______</p><p>______</p>