Suitable indicator for the presence of sewage sludge in marine sediments

Abstract

Traditionally, coastal communities dispose of waste water in the ocean. California has many sewage outfalls that discharge into the Pacific Ocean. The increased use of beaches and tidal areas for recreational activities and commercial shell fishing, coupled with the increased volume of sewage being discharged into the ocean has heightened interest in the problem of marine contamination. This is especially true in areas such as Southern California and the Mediterranean which have experienced tremendous population growth. This study examined marine sediment cores collected from various depths of water and distances from the White's Point's sewage outfall to determine the presence and vertical distribution of selected microorganisms of public health significance. A logarithmic decrease of the indicator bacteria populations with increasing depth in the sediment was observed. Random isolations of Aeromonas occurred but none of the enteric pathogens or viruses included in this study were detected. The classic indicator bacteria were of little value in predicting the presence of enteric pathogens. Clostridium perfringens populations may be a suitable indicator for the presence of sewage sludge in marine sediments and provide a historical record of the deposition and movement of sewage particulates but Clostridium perfringens populations were not related to the presence of pathogens in sediments. Results suggest that the persistence of pathogens in marine sediments are related to abiotic factors and may vary geographically.