Identificador: TDX:509
Autores: Ferré Huguet, Núria
Resumen:
The Ebro River has traditionally concentrated an important number of industries and an intensive agricultural activity through its course of 928 km. The objective of the present study was the diagnosis of the current situation of the Catalan basin of the Ebro River and the Priorat County, by assessing the health risk for the population and the ecological risk. Diverse physico-chemical analyses were carried out and the concentration of several metals (Al, As, Ba, Be, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sb, Se, Sn, Tl, V and Zn) was determined in 20 sampling points in the Ebro River and 10 points in the Priorat County (Siurana, Montsant and Cortiella Rivers, all of them tributaries of the Ebro River). The study was done considering different matrices of the fluvial system: surface water, filtered water, riparian surface sediments, fluvial algae and riparian surface soils. All the data were integrated in order to evaluate the potential effects of the different sources of pollution on the ecosystem. For the environmental risk assessment for the population, samples of water and superficial soils in towns located in the riparian zone of the Ebro River potentially polluted with metals. The potential human health risk associated to the ingestion and dermal absorption of metals through water, as well as the ingestion, inhalation and dermal absorption of metals through soil particles was also calculated. Because of the activities of the chemical plant which manufactures solvents and chlorinated pesticides, the absolute amounts of metals deposited in the Flix Reservoir were very high, meaning a potential pollution of the Ebro River. In general terms, although a point pollution of metals was not observed in river water, the sediments and fluvial biota of the Ebro, especially between the Flix Reservoir and the the Ebro mouth, showed an important pollution for Hg, Cd, Cu, and Pb. Nevertheless, the pollution levels were, for some metals, even higher to those found in Flix. The concentrations of Hg in sediments and biota indicated that there was a certain leaching of Hg, coming from the Flix Reservoir. In the Priorat County, high levels of Fe, Mn and Pb were found in specific locations. They had a natural origin, coming mainly from the erosion and the dragging of the grounds in the riparian zone. The results obtained in this study showed that the detected concentrations would mean a certain toxicological risk for the fluvial ecosystem. In general terms, it was observed that the potential environmental risk for the population, associated with different metals with non-carcinogenic effects, was similar in the different stretches of the Catalan basin of the Ebro River, for both children and adults. Likewise, the excess of As, Fe and Pb could increase the potential non-carcinogenic effects in the population resident in the basin. The natural or anthropogenic pollution of As and Cr in water and soils collected in towns of the riparian zone of the Ebro River, as well of Cd in samples of the Priorat County, might increase the number of cancers in the resident population. This risk cannot be considered as assumable by the population, according to some international standards. In the present study, an hypothesis of worst-case scenario was considered. This assumption usually leads to an overestimation of risks. For instance, it was supposed that all the As present in soils and water was inorganic As, while the relation between total Cr and Cr (VI) was 1:6. Consequently, it would be necessary to carry out some speciation studies of As and Cr. Once these studies were done, the risk and the associated variability should be evaluated again, and the resulting values would probably be lower than those presented here.Key Words: metals, human health risk assessment, ecological risk assessment, Ebro River
Repositori URV