The delineation and growth of a sludge field

The color, odor, organic carbon, and acoustic reflection properties of bottom sediments can be used to delineate the area affected by the Athens sewage outfall. Both color and organic carbon content clearly define the region of high organic buildup around the discharge point. Maximum organic carbon values of over 6% were determined compared to normal regional values of less than 0.5%. The bottom area covered by black anaerobic sediments has increased 7 fold to nearly 9 km 2 in the past 2·5 yr. A smaller core area around the outfall can be easily distinguished by its strong seismic reflection characteristics believed to coincide with the production of methane gas.