WATER QUALITY LAB – Quality of Natural Waters – Physical and Chemical FactorsRead the background information and answer the Pre-Lab question.BACKGROUNDWe depend on a clean water supply for drinking, cleaning and sanitation, recreation, manufacturing, andfor many other purposes. Public health officials and environmental biologis have developed tests thathelp monitor the quality of natural waters and locate sources, and potential sources, of water pollution. Inthis laboratory activity, you will test water samples collected from local waterways and assess them on thebasis of several of the characteristics that scientists use to rate the quality of a body of natural water.TemperatureOne of the most significant characteristics of a body of water is its temperature. Among other things,temperature affects the solubility of oxygen in water, the rate of photosynthesis of aquatic plants, themetabolic rate of aquatic organisms, and the susceptibility of aquatic species to toxins and disease. Watertemperature varies naturally with season and depth, but human activity also can affect temperature insignificant ways. For example, heated water from surfaces such as sunlit parking lots, roads, and sidewalks,and from industrial processes that use water as a coolant, could run into nearby creeks, streams, or rivers.This thermal pollution could be enough to destroy some types of aquatic life. Because the heat capacity of awater is so high, thermally polluted water requires significant dilution andime in order to cool. Heatedwater also facilitates the rapid growth of aquatic plants and algae, so thermal pollution accelerates therate of cultural eutrophication (described in the next section).Nitrogen and PhosphorusPlants require nitrogen and phosphorus to grow. Most fertilizers contain nitrogen and phosphorus in theforms of water-soluble nitrates (NO3) and phosphates (PO,), respectively Rain washes nitrates andphosphates from cultivated land into surface waters, where they promote the rapid growth of plants andalgae, in turn speeding up the rate of eutrophication. Eutrophication is a natural, gradual process thatdrives ecological succession from oligotrophic (nutrient-poor) bodies of water to land. Human activitieslead to cultural eutrophication. Fertilizer runoff from lawns and farms and the nitrates and phosphatesfrom inadequately treated municipal wastewater or from poorly maintained septic systems contributes tocultural eutrophication. Animal waste adds nitrogen and phosphorus to surface water in agricultural areaswith dense animal populations. A sudden influx of nutrients, such as from a flooding event, can lead torapid and uncontrolled population growth of aquatic algae and plants. The subsequent death and decay ofthese plants and alga depletes oxygen levels, killing sensitive aquatic organisms and contributing tosediment buildup. If nitrogen is the limiting nutrient, as in most brackish or marine waters, nitrogen levelsequal to 0.3 ppm or greater can accelerate natural eutrophication. Phosphorus levels of 0.1 ppm or greatercan accelerate natural eutrophication in freshwater, where phosphorus is usually the limiting nutrient.TurbidityThe turbidity test measures the clarity of water. Fine particles, such as eroded soil, and microscopicorganisms, such as plankton, contribute to water turbidity. Turbid waters clog the gills of fish, hinderdisinfection processes, and carry entrapped pollutants downstream. Turbid waters also block sunlight,preventing photosynthesis and increasing water temperature. Turbidity is measured in NephelometricTurbidity Units (NTU). In this exercise, a turbidity tube will be used. As the water is drained from the tube,the black and white pattern of a secchi disk at the bottom of the tube will become visible to the operator.Immediately at this point, the NTU reading is taken on the side of the tube from a measure of the amountof water remaining in the tube.014 Carcana B a Congory Proted n USACAROLINAS-1 Quality of Natural Waters: Physical and Chemical FactorsPre-Lab ActivityDiscuss human activities that could affect the quality of natural waters in your locale.Specifically address temperature, pH, turbidity, and nitrate and phosphate levels.

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A variety of factors continue to have a negative impact on our natural water supplies. Many of…

Discuss human activities that could affect the quality of natural waters in your locale. Specifically address temperature, pH, turbidity, and nitrate and phosphate levels.