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Explain the meaning of the term B.O.D - Leaving Cert Agricultural Science - Question b - 2011
Question b
Explain the meaning of the term B.O.D. Name one agricultural pollutant with a high B.O.D. Explain how the named pollutant affects water quality. Suggest two key elem... show full transcript
Worked Solution & Example Answer:Explain the meaning of the term B.O.D - Leaving Cert Agricultural Science - Question b - 2011
Step 1
Explain the meaning of the term B.O.D.
Answer
B.O.D. stands for Biological Oxygen Demand, which is a measure of the amount of oxygen that microorganisms will consume while decomposing organic matter in water. Specifically, it's quantified as the amount of oxygen used by bacteria when breaking down pollutants in one liter of water over a specified period. A higher B.O.D. indicates a greater amount of organic matter present, suggesting that the water may be more polluted.
Step 2
Step 3
Explain how the named pollutant affects water quality.
Answer
Dairy slurry adversely affects water quality by introducing high levels of organic matter into water bodies. When dairy slurry enters the water, bacteria use oxygen to decompose the organic materials. This process can lead to a drop in dissolved oxygen levels, resulting in deoxygenation. A significant drop in oxygen can endanger aquatic life, causing fish deaths and leading to further issues such as algal blooms and toxicity in the water environment.
Step 4
Suggest two key elements of a waste management strategy for the named pollutant.
Answer
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Collect dairy waste in an enclosed waterproof tank to ensure that rainfall does not dilute the slurry and to prevent runoff into other water bodies.
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Ensure that the storage tank has sufficient capacity, particularly during rainy periods, and avoid applying slurry on frozen or wet soils to minimize contamination risks. Additionally, proper spreading of the slurry on land under suitable conditions should be practiced to reduce its impact on water bodies.