Passage I
Two artificial marshes were built to help reduce the amounts of iron and manganese in, and the acidity of, water seeping into a stream from a coal mine site (see Figure 1). Table 1 shows precipitation, in centimeters (cm); flow rate, in liters per minute (L/min); pH (acidity); and iron and manganese content, in milligrams per liter (mg/L), of inlet and outlet water over 5 days.
Water having a higher level of iron or manganese or a lower pH than the values given in Table 2 is said to be contaminated.
5. According to the data, which of the following actions would be most useful in reducing the iron levels in water released to the stream to a level below the allowed contaminant level given in Table 2 ?
Your Answer is
Correct Answer is A
Explanation
As can be seen from table 1, marshes are effective in reducing the concentration of Iron, so you can add another marsh to further reduce the concentration of Iron