In the winter, a stream flows at 10 m'/s and receives a flow of 5 m'/s from a pipe that contains chloride. the stream's chloride concentration just upstream of the pipe's discharge is 12 mg/l and the runoff pipe's discharge has a chloride concentration of 40 mg/l. chloride is a conservative substance. (a) does wintertime salt usage on the road elevate the downstream chloride concentration above a 20 mg/l water-quality standard? (b) what is the maximum daily mass of chloride (tons/d) that can be discharged through the road runoff pipe without exceeding the water-quality standard?