Question

A farmer applies 1305 kg of a fertilizer that contains 10.0% nitrogen to his fields each year. Fifteen percent (15.0%) of the fertilizer washes into a river that runs through the farm.

If the river flows at an average rate of 0.405 cubic feet per second, what is the additional concentration of nitrogen (expressed in milligrams of nitrogen per liter) in the river water due to the farmer's fertilizer each year?

Answer 1

Answer: 2.77 mg/L.

Step-by-step explanation:

First, we need to find the amount of nitrogen that washes into the river each year:

1305 kg * 10.0% = 130.5 kg of nitrogen

130.5 kg * 15.0% = 19.5775 kg of nitrogen washing into the river

Next, we need to convert the amount of nitrogen into milligrams:

19.5775 kg * 10^6 mg/kg = 19,577,500 mg

Now, we need to find the volume of water in the river each year:

0.405 ft^3/s * 60 s/minute * 60 minutes/hour * 24 hours/day * 365 days/year = 24,948,800 ft^3

24,948,800 ft^3 * 28,316.8 cm^3/ft^3 = 706,966,933,728 cm^3

Finally, we can find the concentration of nitrogen in the river water each year by dividing the total amount of nitrogen by the total volume of water:

19,577,500 mg / 706,966,933,728 cm^3 = 2.77 × 10^-8 mg/cm^3 = 2.77 mg/L

So, the additional concentration of nitrogen in the river water due to the farmer's fertilizer each year is 2.77 mg/L.