Please provide a step-by-step solution.

1) A contaminant weighing 50 kg is uniformly spread throughout a constant-hydrogeometry river. The cross-sectional area of the river is 10 m, the flow rate is 17 ms', and the longitudinal dispersion coefficient is 9 ms!. a) How soon after the spill occurs, will the peak concentration be observed 12 km downstream, and what is the maximum pollutant concentration expected at that location? b) If the river's safety limit for this pollutant is 15 ug L', how long will the location 12 km downstream of the spill be unsafe (i.e., when the pollutant concentration exceeds 15 ug L-')? c) How long would the region 12 km downstream remain dangerous after the spill if the pollutant decays with a first-order reaction rate constant of 5 d'? 1) A contaminant weighing 50 kg is uniformly spread throughout a constant-hydrogeometry river. The cross-sectional area of the river is 10 m, the flow rate is 17 ms', and the longitudinal dispersion coefficient is 9 ms!. a) How soon after the spill occurs, will the peak concentration be observed 12 km downstream, and what is the maximum pollutant concentration expected at that location? b) If the river's safety limit for this pollutant is 15 ug L', how long will the location 12 km downstream of the spill be unsafe (i.e., when the pollutant concentration exceeds 15 ug L-')? c) How long would the region 12 km downstream remain dangerous after the spill if the pollutant decays with a first-order reaction rate constant of 5 d