111
10.1 Introduction
The study area covers the Inner Saronikos Gulf surrounded
by the islands Aegina and Salamina and the eastern coast of
Attika. The Saronikos Gulf communicates with the Aegean
Sea at its south end and is bounded by the coast of Peloponnisos to the west and the coast of Attica to the north and east.
Direct wastewater discharges are one of the main causes of
10
Seasonal and Spatial Nutrient
Dynamics in Saronikos Gulf: The
Impact of Sewage Effluents from
Athens Sewage Treatment Plant
A. Pavlidou, H. Kontoyiannis, N. Zarokanelos, I. Hatzianestis,
G. Assimakopoulou and R. Psyllidou-Giouranovits
A. Pavlidou () · H. Kontoyiannis · N. Zarokanelos · I. Hatzianestis ·
G. Assimakopoulou · R. Psyllidou-Giouranovits
Institute of Oceanography, Hellenic Centre for Marine Research,
47th Km of Athens-Sounio Av.,
19013 Anavyssos, Greece
e-mail: aleka@hcmr.gr
Abstract
This chapter provides a long-term case study illustrating responses of a coastal Gulf in the
Mediterranean Sea to reduced loading of sewage. Saronikos Gulf receives effluents from
the Athens metropolitan area (population over 5 million). Until 1994, sewage discharged
untreated into the surface waters of Keratsini and Elefis Bays. Sewage treatment first started in the Psitallia sewage treatment plant where the wastes discharged into inner Saronikos
Gulf at 63 m depth. By the end of 2004, the secondary stage of the Psittalia sewage plant
was operational.
We examined nitrogen (N) and phosphorus (P) dynamics in the inner Saronikos Gulf
over the last 25 years in relation to these changes in sewage input. Additionally we described changes in the environmental status of inner Saronikos Gulf. Inorganic nutrient
data from 170 cruises obtained during the year 1987–2010 allow us to describe the nutrient
dynamics results and data evaluation. The study was focus on changes in nutrient concentrations between three main periods:
1. Before treatment of sewage
2. During primary treatment of sewage
3. During secondary treatment of sewage
Significant changes in nutrient dynamics noticed after the operation of primary sewage
treatment plant. Nutrient concentration was high in the inner Saronikos Gulf due to the
high amount of primarily treated effluents. After the year 2005, when the secondary sewage
treatment was operational, there was a general decrease in nutrient concentrations in the
inner Saronikos Gulf.
A. A. Ansari, S. S. Gill (eds.), Eutrophication: Causes, Consequences and Control,
DOI 10.1007/978-94-007-7814-6_10, © Springer Science+Business Media Dordrecht 2014
Keywords
Saronikos Gulf · Sewage · Nutrient dynamics · Ratios · Ecological status · Eutrophication
scale
10.1 Introduction
The study area covers the Inner Saronikos Gulf surrounded
by the islands Aegina and Salamina and the eastern coast of
Attika. The Saronikos Gulf communicates with the Aegean
Sea at its south end and is bounded by the coast of Peloponnisos to the west and the coast of Attica to the north and east.
Direct wastewater discharges are one of the main causes of
10
Seasonal and Spatial Nutrient
Dynamics in Saronikos Gulf: The
Impact of Sewage Effluents from
Athens Sewage Treatment Plant
A. Pavlidou, H. Kontoyiannis, N. Zarokanelos, I. Hatzianestis,
G. Assimakopoulou and R. Psyllidou-Giouranovits
A. Pavlidou () · H. Kontoyiannis · N. Zarokanelos · I. Hatzianestis ·
G. Assimakopoulou · R. Psyllidou-Giouranovits
Institute of Oceanography, Hellenic Centre for Marine Research,
47th Km of Athens-Sounio Av.,
19013 Anavyssos, Greece
e-mail: aleka@hcmr.gr
Abstract
This chapter provides a long-term case study illustrating responses of a coastal Gulf in the
Mediterranean Sea to reduced loading of sewage. Saronikos Gulf receives effluents from
the Athens metropolitan area (population over 5 million). Until 1994, sewage discharged
untreated into the surface waters of Keratsini and Elefis Bays. Sewage treatment first started in the Psitallia sewage treatment plant where the wastes discharged into inner Saronikos
Gulf at 63 m depth. By the end of 2004, the secondary stage of the Psittalia sewage plant
was operational.
We examined nitrogen (N) and phosphorus (P) dynamics in the inner Saronikos Gulf
over the last 25 years in relation to these changes in sewage input. Additionally we described changes in the environmental status of inner Saronikos Gulf. Inorganic nutrient
data from 170 cruises obtained during the year 1987–2010 allow us to describe the nutrient
dynamics results and data evaluation. The study was focus on changes in nutrient concentrations between three main periods:
1. Before treatment of sewage
2. During primary treatment of sewage
3. During secondary treatment of sewage
Significant changes in nutrient dynamics noticed after the operation of primary sewage
treatment plant. Nutrient concentration was high in the inner Saronikos Gulf due to the
high amount of primarily treated effluents. After the year 2005, when the secondary sewage
treatment was operational, there was a general decrease in nutrient concentrations in the
inner Saronikos Gulf.
A. A. Ansari, S. S. Gill (eds.), Eutrophication: Causes, Consequences and Control,
DOI 10.1007/978-94-007-7814-6_10, © Springer Science+Business Media Dordrecht 2014
Keywords
Saronikos Gulf · Sewage · Nutrient dynamics · Ratios · Ecological status · Eutrophication
scale