Statistical Analysis of Eco-Toxicologic Data of Mammals from a Polluted Area

Several eco-toxicological studies have shown that insectivorous mammals, due to their feeding habits, easily accumulate high amounts of pollutants in relation to other mammal species. To assess the bio-accumulation levels of toxic metals and their in°uence on essential metals, we quantified the concentration of 19 elements (Ca, K, Fe, B, P, S, Na, Al, Zn, Ba, Rb, Sr, Cu, Mn, Hg, Cd, Mo, Cr and Pb) in bones of 105 greater white-toothed shrews (Crocidura russula) from a polluted (Ebro Delta) and a control (Medas Islands) area. Since chemical contents of a bio-indicator are mainly compositional data, conventional statistical analyses currently used in eco-toxicology can give misleading results. Therefore, to improve the interpretation of the data obtained, we used statistical techniques for compositional data analysis to define groups of metals and to evaluate the relationships between them, from an inter-population viewpoint. Hypothesis testing on the adequate balance-coordinates allow us to confirm intuition based hypothesis and some previous results. The main statistical goal was to test equal means of balance-coordinates for the two defined populations. After checking normality, one-way ANOVA or Mann-Whitney tests were carried out for the inter-group balances

Development of chemical separation processes for the treatment and monitoring of metallic cations and oxoanions in polluted waters

The chemical contamination of natural waters is a global problem with a worldwide impact. Considering the relevance of this problem, this thesis is intended, on one hand, to develop different separation/preconcentration techniques based on membranes ability to permeate anions for the transport of toxic oxyanions of chromium(VI) and arsenic contained in aqueous matrices. In particular, we have investigated supported liquid membranes and polymer inclusion membranes, both of which contain the commercial quaternary ammonium salt Aliquat 336 as a carrier, as well as commercial anion exchange membranes. On the other hand, we have focused on the development of chemical sensors to facilitate the monitoring of several metals from different aqueous matrices. Thus, a selective optical sensor for Cr(VI) based on polymeric membranes containing Aliquat 336 as an ionophore has been designed. Additionally, mercury-based screen-printed electrodes have been evaluated for for cadmium, lead, copper and zinc detection.

Fate and effects of copper in fluvial ecosystems: the role of periphyton

L'activitat humana és una de les majors causes d'elevades concentracions de nutrients i substàncies tòxiques en els ecosistemes fluvials. Entre la gran varietat de factors que alteren aquests ecosistemes, l'eutrofització i la contaminació per metalls pesants són dos dels principals problemes ambientals en països desenvolupats. Els biofilms fluvials (també anomenats comunitats perifítiques) representen una eina valuosa per avaluar els efectes dels contaminants (ex. nutrients i metalls) en els ecosistemes aquàtics. Aquest treball pretén investigar el destí i els efectes del Cu en els ecosistemes fluvials centrant-se en les comunitats perifítiques. Diferents metodologies han estat desenvolupades i/o adaptades per investigar específicament la dinàmica del Cu, la seva toxicitat i bioacumulació en comunitats perifítiques naturals, i la interacció entre l'eutrofització i la toxicitat del Cu en aquests ecosistemes.