Case Studies
Many semi-enclosed bays and coastal areas in the Mediterranean are heavily polluted, mainly by domestic sewage. Collection and analysis of water quality data is the basis for assessing the environmental situation and the risk of pollution. Mathematical models based on stochastic variables are useful tools to quantify the risk of pollution and explore the efficiency of different remedial measures for restoring coastal ecosystems. This is illustrated by the case of the Thermaikos Gulf (NE Mediterranean sea).
Of considerable concern in recent years is the increase in atmospheric CO 2 due to its influence on global climate. Studies so far have concentrated primarily on precipitation and air temperature changes from an assumed doubling in CO 2 (the 2 ร CO 2 scenario). The risk of climatic change, which may influence the water quality in a coastal region, is analysed and a case study from the Thermaikos Gulf in Macedonia, Greece, is presented.
Water drained by rivers carries pollutant substances such as organics, nutrients, fertilisers and pesticides, with an ultimate destination of coastal waters in estuaries. Major rivers discharging into the Mediterranean, such as the Po, Rhone, Ebro and the Nile are heavily polluted. It has been recognised that coastal water pollution from rivers is nowadays one of the most crucial environmental problems. Apart from local sources discharging wastewaters into the river, pollution in river estuaries and deltas originates mainly from diffuse sources, scattered within the entire river basin. Agricultural activities may overload soils with fertilisers and pesticides. Washingoff of the soil by rainfall produces large concentrations of nitrates, phosphorus and toxic chemicals in rivers and coastal waters. Time series data of pollutant concentrations in rivers show high variability both in time and space. Uncertainties related to various kinds of variability in data should be analysed and then quantified by means of adequate mathematical tools. This is shown for the case of the Axios river (Macedonia, Greece).
Surface, coastal and ground waters should be considered in a unified framework. The role of groundwater is vital in the economy for public health and to protect ecological systems. About 75% of the inhabitants of the European Union member states depend on groundwater for their water supply. Public water supply requires a reliable source, which means that the quality, as well as the quantity, should be beyond all doubt in relevant areas.