Question

You are an analyst for an environmental protection agency. A company has applied for a permit to discharge up to 1000 kg/year of baloneyum (By) into a river. Downstream from the discharge, the water is used for crop irrigation and for drinking water. Your agency specifies that the permit should be granted if the most exposed person would receive a By dose of 0.1 mg/day or less. The river has an average flow rate of 100,000 liters per second (l/s). An average of 100 l/s are used for crop irrigation. 10% of the water used for irrigation is taken up by the crops. 1,000,000,000 kg of crops are produced annually. This includes both the edible and inedible part of the plants. By is distributed uniformly throughout the plants. The concentration of By in drinking water is the same as in the river. What I need to find is the amount of By that's being consumed per day by the average person, and construct a Flow Model for it.

Answer 1

FOR THIS WE NEET TO ASSUME SOME THINGS (AS PER WHO)

• Aperson drinks 2 to 4 litres of water per dar and average of 3 litre per day
• percentage of edible plant is 50% and a person consumes 1kg of that yield daily(hypothetically assuming)

discharge of river per day=100000*3600*24=8640000000 l/day

dosage of By per day is= 2.78kg/day=2.78*1000*1000=2780000mg/day

the river has a concentration of (By)=2.78*000*000 /8640000000 =0.0003217mg/litre

volume of water used by crop is=0.1*8640000000*365*=31536000000 l/year

concentration of By in crop yield=0.0003217*31536000000/1000000000=0.0010 mg/kg

by this if we calculate the daily consumption of a person,

by drinking=3*0.0003217=0.0009651 mg/day

by drinking even a hypothetical amount of 10 litre would give an exposure of 0.009651mg/day

and by crop (eating 1 kg a day) =0.0010 mg/day

total of =0.001+0.0009651=0.0019 (almost 0.002mg/day) which is 100 times less than that required for a permit.

Thus the company could be given a permit.