Explain point and non-point source of pollution, Critical Thinking Unit 2 and 3, science homework help

(Unit 2)

1.Explain point and non-point source of pollution. Which one is difficult to regulate?

2.Water is the only chemical that has three phases at ambient temperature. What is the importance of this unique property for the existence of life on earth? 

3.Plot a graph of dissolved oxygen level in a eutrophic lake for 24 hours of hot summer. 

4.Controlling water pollution is controlling human activities.  Explain. 

5.What is the source and sink of DO in surface waters? How can we increase DO in a slow-moving-polluted river. 

6.Does pollution affect the formation of cloud and rain? How?

7.  Suppose the Potomac River is receiving 

◦Waste water effluent with100 g/m3  Phosphorus at 1000 m3/day. 

◦Agricultural runoff of 50 g/m3 Phosphorus at 50 m3/km flow for about 2 km river stretch.

◦Margin of Safety is 5 kg/day

◦Reserve Capacity is 10 kg/day

a)Calculate Total Maximum Daily Load in ton/day

b)If the point source load is 100 kg BOD/day and discharge of 1000 m3/day,  what will be the concentration of BOD in g/m3?

c)If maximum assimilative capacity of the river is 100 kg/day, what will be the maximum pollution load?

7. What is the importance of the following water quality variables:




◦Electric Conductivity (EC)


8. When raw sewerage enters into the river, how does it affect the dissolved oxygen, pHand EC level in the river?

9. Why and how do we measure T,  DO, pH, EC and Turbidity?

(Unit 3)

  1. 1. 
    Water is a molecule of life, improving water quality in Anacostia is improving quality of life of DC residents. What is your take on this statement?

    2.Controlling water pollution is controlling human activities. Justify.

    3.Describe the effect of untreated wastewater on the chemical, physical and biological quality of urban streams or rivers. 

      4.  What are the processes that increase or decrease dissolved oxygen in a river?

      5. Mark did bio-monitoring in A, B and C streams and found the following result. Which stream is in good quality, fair and  polluted status?


    Stream A

    Stream B

    Stream C













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