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High-mountain basins provide a source of valuable water resources. This paper presents hydrological models for the evaluation of water resources in the highmountain Zêzere river basin in Serra da Estrela, Central Portugal. Models are solved with VISUAL BALAN v2.0, a code which performs daily water balances in the root zone, the unsaturated zone and the aquifer and requires a small number of parameters. A lumped hydrological model fails to fit measured stream flows. Its limitations are overcome by considering the dependence of the temperature and precipitation data with elevation and the spatial variability in hydrogeomorphological variables with nine sub-basins of uniform parameters. Model parameters are calibrated by fitting stream flow measurements in the Zêzere river. Computed stream flows are highly sensitive to soil thickness, whereas computed groundwater recharge is most sensitive to the interflow and percolation recession coefficients. Interflow is the main component of total runoff, ranging from 41 to 55% of annual precipitation. High interflows are favored by the steep relief of the basin, by the presence of a high permeability soil overlying the fractured low permeability granitic bedrock and by the extensive subhorizontal fracturing at shallow depths. Mean annual groundwater recharge ranges from 11 to 15% of annual precipitation. It has a significant uncertainty due to uncertainties in soil parameters. This methodology proves to be useful to handle the research difficulties regarding a complex mountain basin in a context of data scarcity.

The aim of this paper is to review the results of the assessment of low-temperature geothermal resources (issue temperatures between 41 and 77°C) that occur in the Portuguese mainland. For this purpose, a multidisciplinary approach, including geologic, tectonic, geochemical, geophysical and isotopic (δ 2 H, δ 18 O, δ 13 C, 3 H and 14 C) techniques, was applied in order to update local and/or regional conceptual circulation models. Three case studies of N-Portugal are presented and discussed. This paper describes different low-temperature geothermal waters presenting similar hydrogeological conceptual models but rather different geochemical signatures (e.g., HCO 3 -Na with pH ≈ 8, HCO 3 /Na/ CO 2 -rich with pH ≈ 7 and HCO 3 -Na with pH ≈ 9, type waters). In fact, in the studied low-temperature geothermal systems, local/ regional high altitude sites associated with highly fractured rocks play an important role in conducting the infiltrated meteoric waters towards the discharge zones near the Spas. The discharge zones are mainly related to the intersection of major regional fault lineaments (and conjugate structures), responsible for creating the mineral waters ascent. In some cases, geochemical and isotopic data point out to the existence of anthropogenic contamination of some geothermal spring waters related to the intense use of fertilizers in areas of widespread agricultural practices.

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Water quality alterations due to forest fires may considerably affect aquatic organisms and water resources. These impacts are cumulative as a result of pollutants mobilized from fires, chemicals used to fight fire, and postfire responses. Few studies have examined postfire transport into water resources of trace elements, including the polycyclic aromatic hydrocarbons (PAH), which are organic pollutants produced during combustion and are considered carcinogenic and harmful to humans. PAH are also known to adversely affect survival, growth, and reproduction of many aquatic species. This study assessed the effects of forest wildfires on groundwater from two mountain regions located in protected areas from north and central Portugal. Two campaigns to collect water samples were performed in order to measure PAH levels. Fifteen of 16 studied PAH were found in groundwater samples collected at burned areas, most of them at concentrations significantly higher than those found in control regions, indicating aquifer contamination. The total sum of PAH in burned areas ranged from 23.1to 95.1 ng/L with a median of 62.9 ng/L, which is one- to sixfold higher than the average level measured in controls (16.2 ng/L). In addition, in control samples, the levels of light PAH with two to four rings were at higher levels than heavy PAH with five or six rings, thus showing a different profile between control and burned sites. The contribution of wildfires to groundwater contamination by PAH was demonstrated, enabling a reliable assessment of the impacts on water quality and preparation of scientifically based decision criteria for postfire forest management practices.

Contamination of water resources by mine effluents is a serious environmental problem. In a old coal mine, in the north of Portugal (São Pedro da Cova, Gondoma),forty years after the activity has ended, a neutral mine drainage, rich in iron (FE) it stills being produced and it is continuously released in local streams (Ribeiro de Murta e Rio Ferreira) and in surrounding lands. The species Lemna minor has been shown to be a good model for ecotoxicological studies and it also has the capacity to bioaccumulate metals. The work aimed test the potential of the species L. minor to remediate this mine effluent, through the bioaccumulation of Fe, under greenhouse experiments and, at the same time, evaluate the time required to the maximum removal of Fe. The results have shown that L. minor was able to grow and develop in the Fe-rich effluent and bioaccumulating this element. Throughout the 21 days of testing it was found that there was a meaningful increase in the biomass of L. minor both in the contaminated and in the non-contaminated waters. It was also found that bioaccumulation of Fe (iron) occurred mainly during the first 7 days of testing. It was found that L. minor has potential for the bioremediation of effluents rich in iron.

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