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The Guadiana River, the fourth major river of the Iberian Peninsula, represents an important aquatic system from a socio, geo and ecological point of view for Portugal and Spain. Important economic activities such as agriculture, tourism and aquaculture are present along with several economic facilities such as harbour (commercial and fishing), marina and small shipyards for construction and repair of small vessels. All these
activities generate wastes some of them toxic to the aquatic environment. That is why in the river there are several aquatic species some of them endemic, rare and even threatened. Recently, the water regime of the river changed due to the construction of the Alqueva Dam (the largest artificial lake in Europe) with the capacity to store 4 150 hm3 of water, which reduced the river flow and the sediment transport to the coastal area. This flow reduction might have an impact in the levels of the stressors present in the river.
The above referred anthropogenic activities and their technological development imply the use of a lot of materials, especially metals, which are generally obtained as a result of mining exploration. The exploration of these metals give origin to the production of acid mining waste containing high amounts of metals some of which are toxic to the aquatic species and to humans. For these reasons, metals are considered traditional
contaminants to the aquatic systems. Furthermore, estuaries are also targeted for several other economic services such as harbours and marinas for receiving commercial ships, ships maintenance and nautical activities, which are another source of pollutants. Indeed, all these activities if not properly managed can introduce chemical stressors such as petroleum hydrocarbons that are highly toxic to the aquatic
environment. On the other hand, the enhancement in urban development, increasing the population that lives near the coast and mainly in the vicinity of the estuaries, results in the production of significant amounts of solid and liquid wastes containing several other chemical stressors. Moreover, the increase of human life expectancy is related to the increasing use of pharmaceutical compounds that are used in hospitals or at
home. Therefore, these compounds were detected with significant concentrations in rivers and coastal áreas around the world. However, the available technology to treat wastewater effluents is unable to eliminate most of them in the waste treatment process reason why they can easily reach the aquatic systems, inducing a serious threat to the aquatic and human health. For that reason, chemical stressors such as these pharmaceutical compounds are considered emerging contaminants to the aquatic environment.
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Universidade do Algarve.Centro de investigação Marinha e Ambiental