Metal pollution in estuaries and high altitude mountains: geographical distribution, evolution in time and toxicological implications
Rodríguez Iruretagoiena, Azibar
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Environmental pollution is considered one of the greatest problems that the world is facing nowadays. Amongst others, some metals and metalloids are chemicals able to cause serious problems to the environment. The anthropogenic inputs of metals and metalloids to the environment have grown constantly since the industrial revolution. Metals and metalloids are no degradable substances and consequently highly durable in the environment. Their toxicity highly depends on their concentration and speciation in each specific environment. In this dissertation, the occurrence, geographical distribution and evolution in time of metals and metalloids was investigated in selected environments. On the one hand, atmospheric metal contamination was studied in different Pyrenean ecosystems, namely lakes and forests. Surface sediments and sediment cores of several high altitude remote lakes were collected and analysed to, respectively, describe the geographical distribution and track the historical records of metallic pollution in the Pyrenees. In addition, the efficiency of bioindicators such as beech leaves, lichens and mosses to monitor atmospheric metal pollution in the Irati Forest was checked. On the other hand, some characteristic estuaries located in different parts of the world were also investigated. The estuaries selected were those of the Tubarão River (Santa Catarina Region, Brazil), the Cávado River (Esposende, Portugal), the Nerbioi-Ibaizabal and the Oka Rivers (both in the Basque Country) and finally the Hugli River, one of the main tributaries of Ganges River (West Bengal, India). Sediments from those estuaries were analysed to describe the geographical distribution and evolution in time of metallic contamination in each studied area. In some cases, water samples and autochthonous oysters were also analysed in order to carry out a more complete assessment of the toxicity associated to the presence of toxic elements. In the case of the estuary of the Hugli River, in addition, a new analytical strategy for the analysis of emerging contaminants like silver nanoparticles in sediments was developed.