Last autumn our office received complaints of a large fish kill along the Ohio River, indicating that someone had discharged highly toxic material into the river. Our water monitoring stations at Cincinnati and Portsmouth, Ohio (119 miles apart) report that a large slug of phenol is moving down the river and we strongly suspect that this is the cause of the pollution. The slug took 9 hours to pass the Portsmouth monitoring station, and its concentration peaked at 8:00 A. M. Monday. About 24 hours later the slug peaked at Cincinnati, taking 12 hours to pass this monitoring station. Phenol is used at a number of locations on the Ohio River, and their distance upriver from Cincinnati are as follows:.Ashland, KY-150 miles upstream Marietta, OH-303Huntington, WV-168 Wheeling, WV-385Pomeroy, OH-222 Steubenville, OH-425Parkersburg, WV-290 Pittsburgh, PA-500What can you say about the probable pollution source?