Avaliação ecológica do efeito combinado de contaminantes ambientais

The assessment of ecological status of lotic freshwater bodies, based on stringent criteria of classification, has been defined by the Water Framework Directive (WFD), as a result of the implementation and optimization of methodologies that integrate physico-chemical, biological, and hydromorphological parameters. It is recognized that the application of this methodology is not easy, because it requires deep technical and scientific knowledge; it is time consuming in its application involving high financial costs. Thus, the main objective of this study was the development of cheaper and faster complementary methodologies that may contribute to the technical application of the classification criteria defined by the WFD, achieving the same final results of evaluation. In order to achieve this main goal, the river Mau, a small mountain river subjected to different stressors (eg, metals, pesticides), was established as the main sampling area. This thesis reviewed the historical development of various biotic indexes and its application in assessing water quality, especially highlighting the new paradigm defined by the WFD, and the corresponding actions developed for optimization and intercalibration of methodologies, evaluating the final state of water bodies. The ecological spatiotemporal characterization of the river Mau focused on the application of the WFD methodology, using at this stage only macroinvertebrates collected during four seasons. Results were compared with historical data of the last three years and they demonstrated that the river is in good condition. However, the ecological quality decreased at certain locations indicating that organisms were subjected to some type of disturbance. As the ecological quality can be conditioned by pulses of contamination from the sediments, in environmental adverse conditions, assays were performed with elutriates, obtained from sediments collected near the mining complex Braçal-Palhal. Results showed that this method was effective achieving the state of contamination, which may be important in prioritizing/scoring of critical areas within river ecosystems potentially impacted, using the WFD methodology. However, this methodology requires the collection of sediment which can promote the modification and / or loss of contaminants. To solve this potential problem, we developed a new methodology to obtain similar results. For this, we used a benthic microalga, belonging to the Portuguese flora, sensitive to organic pollution and metals. This methodology was optimized for application in situ, by immobilization of diatom in calcium alginate beads. The results showedthat their sensitivity and normal growth rate are similar to data obtained when used free cells of diatom. This new methodology allowed the achievement of a very quick response on the degree of contamination of a site, providing a complementary methodology to WFD.

Characterization of water-soluble organic compounds in bioaerosols by liquid chromatography and fluorescence spectroscopy

In the last decades, the effects of the air pollution have been increasing, especially in the case of the human health diseases. In order to overcome this problem, scientists have been studying the components of the air. As a part of water-soluble organic compounds, amino acids are present in the atmospheric environment as components of diverse living organisms which can be responsible for spreading diseases through the air. Liquid chromatography is one technique capable of distinguish the different amino acids from each other. In this work, aiming at separating the amino acids found in the aerosols samples collected in Aveiro, the ability of four columns (Mixed-Mode WAX-1, Mixed-Mode HILIC-1, Luna HILIC and Luna C18) to separate four amino acids (aspartic acid, lysine, glycine and tryptophan) and the way the interaction of the stationary phases of the columns with the analytes is influenced by organic solvent concentration and presence/concentration of the buffer, are being assessed. In the Mixed-Mode WAX-1 column, the chromatograms of the distinct amino acids revealed the separation was not efficient, since the retention times were very similar. In the case of lysine, in the elution with 80% (V/V) MeOH, the peaks appeared during the volume void. In the Mixed-Mode HILIC-1 column, the variation of the organic solvent concentration did not affect the elution of the four studied amino acids. Considering the Luna HILIC column, the retention times of the amino acids were too close to each other to ensure a separation among each other. Lastly, the Luna C18 column revealed to be useful to separate amino acids in a gradient mode, being the variation of the mobile phase composition in the organic solvent concentration (ACN). Luna C18 was the column used to separate the amino acids in the real samples and the mobile phase had acidified water and ACN. The gradient consisted in the following program: 0 – 2 min: 5% (V/V) ACN, 2 – 8 min: 5 – 2 % (V/V) ACN, 8 – 16 min: 2% (V/V) ACN, 16 – 20 min: 2 – 20 % (V/V) ACN, 20 – 35 min: 20 – 35 % (V/V) ACN. The aerosols samples were collected by using three passive samplers placed in two different locations in Aveiro and each sampler had two filters - one faced up and the other faced down. After the sampling, the water-soluble organic compounds was extracted by dissolution in ultra-pure water, sonication bath and filtration. The resulting filtered solutions were diluted in acidified water for the chromatographic separation. The results from liquid chromatography revealed the presence of the amino acids, although it was not possible to identify each one of them individually. The chromatograms and the fluorescence spectra showed the existence of some patterns: the samples that correspond to the up filters had more intense peaks and signals, revealing that the up filters collected more organic matter.

Concentration of human pollution tracers with ionic liquids

The main objective of the present thesis consists on the development of an analytical preconcentration technology for the concomitant extraction and concentration of human pollution tracers from wastewater streams. Due to the outstanding tunable properties of ionic liquids (ILs), aqueous biphasic systems (ABS) composed of ILs can provide higher and more selective extraction efficiencies for a wide range of compounds, being thus a promising alternative to the volatile and hazardous organic solvents (VOCs) typically used. For that purpose, IL-based ABS were employed and adequately characterized as an one-step extraction and concentration technique. The applicability of IL-based ABS was verified by their potential to completely extract and concentrate two representative pharmaceutical pollution tracers, namely caffeine (CAF) and carbamazepine (CBZ), from wastewaters. The low concentration of these persistent pollutants (usually found in μg·dm-3 and ng·dm-3 levels, respectively) by conventional analytical equipment does not permit a proper detection and quantification without a previous concentration step. Preconcentration methods commonly applied are costly, timeconsuming, with irregular recoveries and make use of VOCs. In this work, the ABS composed of the IL tetrabutylammonium chloride ([N4444]Cl) and the salt potassium citrate (K3[C6H5O7]) was investigated while demonstrating to be able to completely extract and concentrate CAF and CBZ, in a single-step, overcoming thus the detection limit of the applied analytical equipment. Finally, the hydrotropic effect responsible for the ability of IL-based ABS to extract and concentrate a wide variety of compounds was also investigated. It was shown that the IL rules the hydrotropic mechanism in the solubility of CAF in aqueous solutions, with an increase in solubility up to 4-fold. Moreover, the proper selection of the IL enables the design of the system that leads to a more enhanced solubility of a given solute in the IL-rich phase, while allowing a better extraction and concentration. IL-based ABS are a promising and more versatile technique, and are straightforwardly envisaged as selective extraction and concentration routes of target micropollutants from wastewater matrices.