1. (20 points) A lake with a constant volume of 5108m3 and outflow of 106m3/ day is contaminated by naphthalene leaking from groundwater at a rate of 30kg/ day. A nearby industrial site also uses naphthalene, and discharges in the river flowing into the lake. The discharge stream of residual naphthalene from the industrial site has a flow of 1,000m3/ day and contains 10kg/m3. The stream mixes with the river flow with does not contain naphthalene, and you can consider the total mixed flow (river + discharge) to match the outflow of the lake. Naphthalene decays in the lake following a first-order rate law with a rate constant of 103d1, but the level of naphthalene in the lake remains high enough to cause concerns for human and environmental health. New environmental regulations will ban naphthalene use by the industry. a) What is the current (before the naphthalene ban) and future (after the naphthalene ban) steady-state concentrations of naphthalene in the lake? Please give your concentrations in mg/L. b) After the naphthalene ban, how long would it take to get the concentration to below 0.1 mg/L, which is considered safe? Please give your time in days