Nitrate concentrations exceeding 44.3 mg NO3-/L are a concern in drinking water due to the infant disease, methemoglobinemia. Nitrate concentrations near three rural wells were reported as 0.01 mg NO3- N/L, 1.3 mg NO3- N/L, and 20.0 mg NO3- N/L. Do any of these three wells exceed the 44.3 mg NO3-/L level?

To determine if any of the three wells exceed the 44.3 mg/L nitrate concentration level, we need to convert the reported nitrate concentrations from mg NO3- N/L to mg NO3-/L. This is necessary because the 44.3 mg/L limit is given in terms of nitrate concentration.

To convert from nitrate in terms of NO3- N/L to NO3-/L, we need to consider their molecular weights. The molecular weight of NO3- is 62.0049 g/mol, and the atomic weight of nitrogen (N) is 14.0067 g/mol.

Converting from mg NO3- N/L to mg NO3-/L:

(Concentration in mg/L) * (molecular weight of NO3-/molecular weight of NO3- N) = Concentration in mg NO3-/L

For the three reported concentrations:

1) 0.01 mg NO3- N/L:
(0.01 mg/L) * (62.0049 g/mol/14.0067 g/mol) = 0.0449 mg NO3-/L

2) 1.3 mg NO3- N/L:
(1.3 mg/L) * (62.0049 g/mol/14.0067 g/mol) = 5.7871 mg NO3-/L

3) 20.0 mg NO3- N/L:
(20.0 mg/L) * (62.0049 g/mol/14.0067 g/mol) = 89.2193 mg NO3-/L

Now we have converted all three concentrations to mg NO3-/L. Comparing each concentration to the limit of 44.3 mg NO3-/L:

1) 0.0449 mg NO3-/L < 44.3 mg NO3-/L: This well does not exceed the limit.
2) 5.7871 mg NO3-/L < 44.3 mg NO3-/L: This well does not exceed the limit.
3) 89.2193 mg NO3-/L > 44.3 mg NO3-/L: This well exceeds the limit.

Based on the calculations, the third well with a reported nitrate concentration of 20.0 mg NO3- N/L exceeds the 44.3 mg NO3-/L limit and is a concern for drinking water due to the risk of methemoglobinemia.