Water Quality Testing Module 3 Unit 2 and 3 PDF

Water Quality Testing Module 3 Unit 2 and 3 Instructor: Rayanna Boodram Test Methods Whether the water is tested in a laboratory or in the field by an aquaculturalist, general test methods include titrimetric, colorimetric, and electronic meters. For many wat...

Water Quality Testing Module 3 Unit 2 and 3 Instructor: Rayanna Boodram Test Methods Whether the water is tested in a laboratory or in the field by an aquaculturalist, general test methods include titrimetric, colorimetric, and electronic meters. For many water quality tests, companies sell test kits complete with all of the chemicals and standards. Test Methods Titrimetric Titrimetric analyses use a solution of known strength— the titrant— which is added to a known or specific volume of sample in the presence of an indicator. The indicator produces a color change, indicating that the titration is complete. To calculate the results, the amount of titrant used is measured. A microburette or precision pipet adds the titrant. Test Methods Colorimetric Beer’s law states that the higher the concentration of a substance, the darker the color produced in a test reaction. This law provides the basis for determining the concentration of many substances in water samples. Known chemical reactions produce typical colors. The concentration that these colors represent is determined visually by comparing the color that is obtained from a sample to a set of standards. Because the human eye’s interpretation can be quite subjective, electronic colorimeters provide a more accurate indication of color intensity. Colorimeters consist of a light source passing through a sample that is measured on a photodetector, providing an analog or digital readout. Electronic colorimetric readings also compare the sample value to readings from a set of standard (known) readings. Test Methods Electronic Meters Modern electronics provides the aquaculturalist with a variety of electronic meters designed to measure specific water-quality factors, including pH, total dissolved solids, conductivity, dissolved oxygen, temperature, and turbidity. Like the chemical methods, standard solutions are important. They are used to calibrate the electronic meter. Using test kits or electronic meters, aquaculturalists regularly check the oxygen, pH, carbon dioxide, and ammonia of water in production. Test Methods Flesh Analysis Fish flesh is often taken in large-scale fish kills to analyze for possible toxicants. Pesticides and heavy metals are the most common items investigated. Some metals will normally be found in much greater concentration in the flesh than in the water in which that fish swims. Some pesticides characteristically also accumulate in quantities much greater than are present in the water.  Test Methods Sediments Sediments or muds from pond bottoms are usually checked for heavy metals and pesticides. Measurements of heavy metals in sediments are typically much higher than those measured in the water column. Usual measures of lake sediments in mg/l include: Cobalt (Co), 4 to 40 Manganese (Mn), 100 to 1,800 Chromium (Cr), 50 to 250 Mercury (Hg), 0.1 to 1.5 Copper (Cu), 20 to 90 Nickel (Ni), 30 to 250 Iron (Fe), 11,000 to 70,000 Zinc (Zn), 50 to 250 Lead (Pb), 10 to 100 Test Methods Sediment pesticides are often checked when establishing a particular site as suitable for fish culture. The very persistent pesticides are the object of such checks, and organochlorines are usually tested as “scans.” Sediments are also checked for pesticides when they are suspect in a catastrophe situation. The testing laboratory should be advised as to which type of pesticide has been used. Otherwise, many useless tests may be conducted that result in a very high expense to the pond owner.  Disposing of Aquaculture Water Each year, agricultural practices come under closer scrutiny for evidence that they may deteriorate the environment. Some claims against agriculture are valid, some are not. Agriculturalists and aquaculturalists respond to valid claims by changing practices. Clean, plentiful water is the life blood of successful aquaculture. Wastewater is the major pollutant from aquaculture. Water used in aquaculture carries with it any uneaten feed, fish wastes or excrement, chemicals, dead fish, sediments, algae, and escaped fi sh. This wastewater is known as effluent, and it is produced by hatcheries, rearing tanks, processing plants, ponds, raceways, flushing, harvesting drawdown, and haul tanks. Aquaculturalists recognize that wastewater harms the environment and must be creatively dealt with. Improper disposition of wastewater can cause damage to the aquatic species being cultured. Finally, wastewater disposal is regulated by laws, regulations, and agencies. Pollution Wastewater pollution can cause a number of problems for the environment. Dead fish look unsightly and smell. Nutrients in the wastewater cause the aging or eutrophication of a body of water. The wastewater increases sedimentation and may contain weed seeds. Wastewater smells because of decaying materials and the gases released. Finally, wastewater may contain a species of fish that could genetically damage wild fish or become a trash fish in the wild.  Treating and Disposing Along with plans for adequate clean water, disposal of wastewater receives considerable attention. Basically, six methods are used to treat wastewater: 1. Settling ponds or vats 2. Irrigation water 3. Percolation ponds 4. Filtering systems 5. Hydroponics 6. Chemical additives Treating and Disposing Settling Ponds or Vats Wastewater moves into the settling area, where the solids settle to the bottom and the top water is released into the environment or a stream. Solid material needs to be removed occasionally.  Treating and Disposing Irrigation Water As long as the wastewater contains no chemicals harmful to a fi eld crop, it can be used for irrigation. Some of the substances in the wastewater serve as fertilizer for the crop Treating and Disposing Percolation Ponds These ponds are similar to settling ponds, but the bottoms of the ponds are porous. Water absorbs into the ground. This method has the potential of polluting groundwater supplies. Filtering Systems Elaborate filtering systems prepare wastewater for release into the environment. These filtering systems are often expensive and require a high level of maintenance. Treating and Disposing Hydroponics Wastewater from aquaculture provides the nutrified water for raising plants hydroponically. Hydroponics is the growing of land (field) crops with their roots dangling in nutrified water. Often, the wastewater from aquaculture contains nutrients below the level required by the plants. Chemical Additives Chemicals or biochemicals added to wastewater can remove pollutants. This method requires care because the improper addition of chemicals to the water could also create pollution. Aquaculturalists deal with wastewater by using a modification or a combination of the six basic methods. What they choose to do could be influenced by the regulations that apply to wastewater in their area. Questions What form of nitrogen is the most harmful to fish? Why List three reasons why wastewater from aquaculture facilities is considered a source of pollution. DIY- Construct a Secchi disk. Use a 12-in by 12-in piece of sheet metal. Mark an 8-in (20 cm) circle on the sheet metal. Make a small hole in the center. Paint the top of the disk with flat white paint. Divide the circle into equal quadrants. Paint two opposite quadrants flat black. Insert an eye bolt through the hole in the center and place a lead weight on the bolt before attaching the nut. Attach a calibrated line to the eye bolt. Use the Secchi disk to take readings on a pond. Lower the disk into the water until it just disappears. Record the measurement on the calibrated line. Lower the disk until it disappears. Then, raise it until it reappears. Record this measurement and use the average of the two.