##### Reference no: EM131219934

**Environmental Risk Analysis Assignment**

Q1. A pipe break in a plastics manufacturing plant results in the sudden release of 200 kg of vinyl chloride to a river. The river has a width of 100 m, a flow rate of 120 m^{3}/s, a velocity of 0.6 m/s, and a slope of 0.00015. A water intake is located 10 km downstream from the plant.

a. When will the concentration be at a maximum at the water intake?

b. What will be the maximum concentration at the water intake?

Q2. Consider the continuous release of chromium to a small lake in the liquid effluent from an electroplating shop. The effluent flow rate is 400 L/yr and the chromium concentration in the effluent is 5 g/L. The lake is 4 m deep, and has a volume of 5 x 10^{5} m^{3}, and the flow rate through the lake is 5 x 10^{3} m^{3}/yr. The suspended solids concentration in the lake is 500 mg/L, the settling velocity of the solids is 0.06 m/yr, and the distribution coefficient for chromium is 400 L/kg.

a. What fraction of chromium is sorbed to the solid phase?

b. What is the steady-state concentration of chromium in the aqueous phase?

c. What is the chromium concentration in the sediment?

Textbook - QUANTITATIVE ENVIRONMENTAL RISK ANALYSIS FOR HUMAN HEALTH by Robert A. Fjeld, Norman A. Eisenberg and Keith L. Compton.