1. A pond receives urban runoff from a stormwater collection and equalization system. The system discharges water to the pond at a steady rate of 2 L/s. The storm water

contains two pollutants of interest: chloride (CI) at a concentration of 500 mg/L and ammonium(NH4*) at a concentration of 2 mg/L. Chloride is conservative, but ammonium degrades in the pond with a pseudo-first-order reaction rate constant of 0.05 day1. The pond also receives water (at a steady rate of Q) from a pristine stream with negligible concentrations of Cl and NH4*. The pond is well-mixed and is equipped with an effluent weir that keeps its volume at a constant 10.000 m3, The concentration of chloride in stream effluent stream is 100 mg/L a. What is the concentration of NH4* (in mg/L) in this stream? b. Why are NH4* inputs to environmental surface waters a problem? Give two reasons.