Engineers performed four studies to better understand how pollutants behave in a
ID: 1709873 • Letter: E
Question
Engineers performed four studies to better understand how pollutants behave in a natural river. Explain why they did each test.
a) The engineers collected a sample of water from the river just downstream from a wastewater discharge and 100 mg of a herbicide was added to it. They measured the
concentration of the herbicide over time in the sealed laboratory bottle.
b) The engineers collected sample of water from the same location as above and sealed the bottle. The concentration of oxygen dissolved in the water was measured after five days.
c) The engineers collected a sample of water from the same location and measured the concentration of ammonia in the sample.
d) The engineers added NaCl to the river just downstream from a wastewater discharge and measured NaCl concentrations in the water downstream for several days.
Explanation / Answer
a) This first test the have conducted to determine the organic content in the water.
b) This test they have done to determine biochemical oxygen demand ie the mount of oxygen required to breakdown organic material present in the sample.
c) the concentration of ammonia is determined because it is one of the most important pollutant it is relatively commom but can be toxic causing lower reproduction growth or death.the neutral unionized form of NH3 is highly toxic.
d) here the salt is added to the water because as soon as we add nacl it gets disolved and salt dilution technique can be used to measure the stream flow where conventional current metering is inaccurate
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