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(46-27) Evolution of the Nutrient Composition of an Urban Sewage Disposal in Tide-Lands. A., Acevedo-Merino1, C., Garrido-Pérez1, E., Nebot-Sanz1, D., Sales-Márquez*,1, 1 Faculty of Marine and Environmental Sciences, University of Cadiz., Puerto Real, Cádiz., Spain ABSTRACT- During last two years, water quality of a marsh and tide-lands estuary in the Southwest of Spain was evaluated. In the estuary head, the system is directly affected by an effluent of a urban sewage treatment plant that increase the nutrient and pathogens natural concentrations. The analytical results show a clear gradient of dilution along the natural system, about of 4 Km. This gradient was due to two processes: (I) dilution, and (II) chemical and/or biochemical decay processes. In order to identifying the contribution of each one, this study attempt an approach for determining the physical-chemical and biological evolution of the composition of the urban sewage in natural waters without dilution processes. The results obtained show that ammonia and faecal coliforms were the best indicators of autodepuration process in the estuary of Iro River. Key words: nutrients, pathogens, dilution, autodepuration |
