If an industry discharges 10,000 gallons a day with a copper concentration of 5 mg/L, what is the concentration in pounds per day?

To determine the concentration in pounds per day, we start with the given values: a discharge of 10,000 gallons per day and a copper concentration of 5 mg/L.

First, we need to convert the volume of water from gallons to liters because the concentration is given in mg/L. There are approximately 3.785 liters in a gallon, so:

10,000 gallons/day * 3.785 L/gallon = 37,850 L/day

Next, we take the concentration of copper, which is 5 mg/L, and apply it to the total volume of water. This allows us to calculate the total mass of copper in milligrams:

5 mg/L * 37,850 L/day = 189,250 mg/day

To convert milligrams to pounds, we use the conversion factor where 1 pound is equal to 453,592 milligrams:

189,250 mg/day ÷ 453,592 mg/lb = 0.4167 lb/day

Rounding this to two decimal places yields approximately 0.42 lb/day. Therefore, the correct answer reflects the calculated mass of copper discharged per day in pounds, confirming that the concentration aligns with option B.