The Dissolved Oxygen Discussion

Discussion; The dissolved oxygen (DO) is oxygen that is dissolved in water. Dissolved oxygen analysis measures the amount of gaseous oxygen (O2) dissolved in an aqueous solution. Oxygen gets into water by diffusion from the surrounding air, by aeration (rapid movement), and as a waste product of photosynthesis. Total dissolved gas concentrations in water should not exceed 110 percent. Concentrations above this level can be harmful to aquatic life. Fish in waters containing excessive dissolved gases may suffer from "gas bubble disease"; however, this is a very rare occurrence. The bubbles or emboli block the flow of blood through blood vessels causing death. External bubbles (emphysema) can also occur and be seen on fins, on skin and on other tissue. Aquatic invertebrates are also affected by gas bubble disease but at levels higher than those lethal to fish. Adequate dissolved oxygen is necessary for good water quality. Oxygen is a necessary element to all forms of life. Natural stream purification processes require adequate oxygen levels in order to provide for aerobic life forms. As dissolved oxygen levels in water drop below 5.0 mg/l, aquatic life is put under stress. The lower the concentration, the greater the stress. Oxygen levels that remain below 1-2 mg/l for a few hours can result in large fish kills. A high DO level in a community water supply is good because it makes drinking water taste better. However, high DO levels speed up corrosion in water pipes. For this reason, industries use water with the least possible amount of dissolved oxygen. Water used in very low pressure boilers have no more than 2.0 ppm of DO, but most boiler plant operators try to keep oxygen levels to 0.007 ppm or less. Oxygen dissolves in water at very low concentrations. Our atmosphere is 20% oxygen or 200,000 ppm but seldom will a pond have more than 10 ppm oxygen dissolved in its’ water. Dissolved oxygen concentrations below 3 ppm stress most species of fish and

concentrations below 2 ppm will kill some species. Often fish that have been stressed by dissolved oxygen concentrations in the range of 2 or 3 ppm will become susceptible to disease. Oxygen dissolves into water from two sources: the atmosphere and from plants in the water. The primary source of oxygen for a river is from microscopic algae (phytoplankton) or submerged plants. In the presence of sunlight, these produce oxygen through photosynthesis and release this oxygen into the river water. At night and on very cloudy days, algae and submerged plants remove oxygen from the water for respiration. During daylight hours plants normally produce more oxygen than they consume, thus providing oxygen for the fish and other organisms in the river .Oxygen depletions are the most common cause of fish kills in rivers. Most oxygen deletions occur in the summer months because 1) warm water holds less dissolved oxygen than cool or cold water, and 2) because the river’s oxygen demand is greater in warm water than in cold water. Fish kills from oxygen depletions can range from “partial” to “total”. In a partial kill the dissolved oxygen level gets low enough to suffocate sensitive species and large fish, but many small fish and hardy species survive. Most oxygen depletions cause partial fish kills; total fish kills are relatively rare in recreational river except for those with extremely high fish populations (>1,000 pounds/acre).The experiment conduct to test for dissolved oxygen in four different sample of water from different section of the bog walk river show that there is a high dissolved oxygen contain in the bog walk river. In sample one of the river water the dissolved oxygen contain was 8.4ppm.This show that the water oxygen contain is adequate for most species but there was no fish in the site one water. The aquatic fauna that was in the water is yellow snail. The amount of dissolved oxygen in the river water may be because of the aquatic flora that was in the water because plant that live in water help to produce oxygen for the organisms that live in the water. The water sample from site two show a dissolved oxygen of

10.5ppm this may because of the large amount of water Lilly in the water that was dam with small fish in the water of the upper section of the dam while there was various species of aquatic flora with fish and the water from the upper section of the dam was pumped in to the lower section of the dam in the river channel that cause the oxygen contain in the river to increase. The oxygen contain of the water was optimal from aquatic faunas because there was fish in the water while the sample of water that was taken from site there show a dissolved oxygen contain of 10.1ppm this may be because of the large of plant that was in the river water and the river water was come from the area were sample two was collected. However the water was optimal for aquatic fauna there was a reduce in the water oxygen contain because the water in site three is coming from site two this may be because the water flow stop in site three and the oxygen contain of the water from site three was 5ppm because there was lots of waste such as bamboo and solid waste in the water there was algae at one section of the river that may help to decrease the oxygen contain of the water however the water oxygen contain was sufficient for aquatic fauna because there was small fish in the water. The oxygen contain of a water is very important for the aquatic fauna because aquatic fauna dependent a oxygen in water to survive.

Conclusion; It was concluded that the oxygen contain of water in the bog walk river is sufficient for aquatic fauna because the results was 8.4ppm,10.5ppm,10.1ppm and 5ppm from sample one to four respectively and the oxygen contain of a water is very important for the aquatic fauna because aquatic fauna dependent a oxygen in water to survive.