Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Dissolved Oxygen Test Dissolved oxygen (DO) is critical for the animals that live in the water. Just as land-based creatures need oxygen to live, so do aquatic animals. The more oxygen dissolved in water is usually better for aquatic life. You typically have the greatest diversity of life in waters with high levels of dissolved oxygen. Oxygen comes into water in two ways. The first is photosynthesis. Plants and algae in the water produce oxygen during the daytime. Those same plants consume oxygen during the night. If there are many plants in the water, oxygen levels may increase as the day goes on and plants are photosynthesizing more. Oxygen also enters the water directly from the air. Moving water and wave action mixes and dissolves oxygen into it. Waterfalls and rapids tend to increase the amount of oxygen in water. As water heats up, gases are driven out of the water. For example, a can of soda pop has carbon dioxide gas dissolved in it, which we call carbonation. As the pop heats up, the carbon dioxide is driven out and the pop goes flat. Warmer water will have less oxygen in it than colder water. The Test Where you get your water and how you collect it for dissolved oxygen is important. Make sure you fill and cap your sample bottle under the water. After it is capped, if there are air bubbles in the sample, you need to collect it again. Try to collect water in the middle of the stream – not too close to the top, bottom or edges. Try to get the sample in a portion of the stream that “looks” like the rest of the stream, with the same speed and amount of rocks. After you conduct the chemical testing, you will get a dissolved oxygen reading in ppm or parts per million. Because the amount of oxygen water can hold changes on temperature, you need to use the chart below to determine the percent of saturation of oxygen in the water. If your dissolved oxygen reading is under 90 percent saturation, you might want to figure out why. Here are some common reasons: 1. Lack of turbulence in the water – Are the rocks and gravel that are normally at the bottom of the stream covered by sand or silt? If so, erosion control measures might help. 2. Temperature change – If the water is very warm, it can drive out dissolved oxygen. 3. “Muck” – What does the bottom of the stream look like? If there is a lot of decaying plant and animal matter, which looks like black muck, that can use up much of the oxygen in the water http://msue.anr.msu.edu/news/youth_water_quality_tests_part_2_dissolved_oxygen