J. Espinha Marques

Water Quality Concerns Due to Forest Fires: Polycyclic Aromatic Hydrocarbons (PAH) Contamination of Groundwater From Mountain Areas

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.

A dynamic map application for the assessment of groundwater vulnerability to pollution

AbstractGroundwater pollution is a major environmental concern at global scale. It usually restricts the use of water resources for domestic, agricultural or industrial purposes, with significant impact on human well-being. Aquifer remediation may be very difficult or even impossible due to technical and/or economic constraints. To help prevent groundwater pollution, several cartographic methods have already been developed. Geographical information systems (GIS) provide useful tools for understanding the spatial distribution of groundwater vulnerability to pollution. This paper presents a new tool to produce groundwater vulnerability to pollution maps under a GIS open source environment. This application was developed within the QGIS software. The tool determines the spatial distribution of the DRASTIC index and incorporates all the procedures required under a single plugin. One of the main advantages of this application is the easiness to use and the possibility of viewing different results modifying indexes, weight values and table descriptions or importing the input data attribute file description. The user can also generate the maps according to his perception regarding each aquifer system. This application is free and presents a valuable contribution to assess and map groundwater vulnerability to pollution through a GIS open source.

A comprehensive analysis of groundwater resources using GIS and multicriteria tools (Caldas da Cavaca, Central Portugal): environmental issues

Hard-rock watersheds are essentially confined to fractured and weathered horizons, but they are a source of valuable water resources at a regional level, namely for domestic, industrial and agricultural purposes, and public supply. They commonly exhibit complex geological bedrock and morphological features as well as distinctive gradients in rainfall and temperature. Hydromineral and geothermal resources have relevant economic value both for the bottled water/thermal spas industry and for energy supply. A comprehensive evaluation and integrated groundwater resources study has been carried out for the Caldas da Cavaca hydromineral system in Central Portugal, using hydrogeomorphology and GIS mapping techniques. Thematic maps were organised from a geodatabase comprising several layers, namely lithology, tectonic lineaments density, slope, drainage density, rainfall, net groundwater recharge and water quality. Normalised weights were assigned to all these categories according to their relative importance to groundwater potential, based on their effectiveness factors. Hydrogeochemistry, natural radioactivity and intrinsic vulnerability assessment (GOD-S, DRASTIC-Fm, SINTACS, SI indexes) issues were also cross-checked. Based on all the compiled information, a hydrogeomorphological map was produced. This multidisciplinary approach highlights the importance of hydrogeomorphological mapping as a tool to support hydrological conceptualisation, contributing to groundwater decision-making process in different stages, like water resources management and territory planning, and thus, to environmental sustainability.

Bioremediation of an Iron-Rich Mine Effluent by Lemna minor

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, Gondomar), 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.

Role of high mountain areas in catchment hydromineral resources - Northern/Central Portugal: environmental issues.

This study summarizes the results of geological, geomorphological, tectonic, geochemical, geophysical, hydrogeological and isotopic techniques in hydromineral resources assessment (issue temperature between 27oC and 45oC). Two case studies are presented: i) Serra da Estrela mountain region, the highest mountain in Portuguese mainland and ii) Serra do Marao mountain region. A special emphasis is dedicated to the recharge and discharge processes and the role of snowmelt as a source of hydromineral resources. Since local Spas are particularly dependent on water quality, the existence of mixing between hydromineral waters and local shallow groundwaters is also considered.

Revision of the hydrogeological conceptual models of two Portuguese thermomineral water systems: similarities and differences

This paper aims to highlight the role that the assessment of hydrogeological conceptual models of the thermomineral water systems of a given region plays in the sustainable management and protection of its resources (e.g., possible drilling plans to capture thermomineral waters with higher flow rate and/or temperature) and development (use of thermomineral waters in the various forms). Therefore, a multi and interdisciplinary approach from a variety of scientific fields of the domain of geoscience such as geology, geochemistry, hydrogeology, and isotope hydrology was applied. Despite the contrasting features of the two thermomineral systems studied, namely, different geochemical signatures ascribed to distinct geological environments (e.g., the Caldas do Moledo system HCO3-Na with 8 < pH < 9, and the Cabeço de Vide system Na-Cl/Ca-OH with pH ≈ 11.5), the respective hydrogeological conceptual models show clear similarities. Regional/local higher altitude areas associated with highly fractured rocks play an important role in conducting the infiltrated meteoric waters towards the discharge zones near the Thermal Spas. The discharge zones are mainly related to the intersection of the main local/regional fault lineaments and conjugate structures, responsible for promoting the ascent of the thermomineral waters. The use of thermomineral waters in spas, bottling industries, or low-temperature geothermal facilities often promote social and economic development at local and/or regional scale. In many cases, it is even a major, if not the main, source of local/regional development. Thus, the importance of such multidisciplinary studies for the sustainable management of these important types of georesources is obvious.

Simple statistical models for relating river discharge with precipitation and air temperature—Case study of River Vouga (Portugal)

Simple statistical models were developed to relate available meteorological data with daily river discharge (RD) for rivers not influenced by melting of ice and snow. In a case study of the Vouga River (Portugal), the RD could be determined by a linear combination of the recent (PR) and non-recent (PNR) atmospheric precipitation history. It was found that a simple linear model including only PR and PNR cannot account for low RD. The model was improved by including non-linear terms of precipitation that accounted for the water loss. Additional improvement of the models was possible by including average monthly air temperature (T). The best model was robust when up to 60% of the original data were randomly removed. The advantage is the simplicity of the models, which take into account only PR, PNR and T. These models can provide a useful tool for RD estimation from current meteorological data.

Groundwater resources in a Mediterranean mountainous region: environmental impact of road de-icing

Water from mountainous regions is a strategic natural resource. In Mediterranean mountainous regions, which, in many cases, correspond to protected areas, high-altitude roads are often the main threat to the sustainability of water resources. In these regions, the regular socioeconomic functioning requires frequent road de-icing operations which normally consist of spreading NaCl and other chemicals, such as CaCl2, in pavements. The main purpose of this research is to assess the environmental impact of road de-icing on groundwater resources in a Mediterranean mountainous region and to describe it by means of a hydrogeological conceptual model. The research focused in a cross-sectional sector located in Serra da Estrela (Central Portugal), where a hydrogeological inventory was carried out, followed by hydrogeochemical and hydrogeophysical studies. The results clearly identify different hydrogeochemical signatures in polluted (Cl–Na facies and higher EC) and unpolluted (HCO3–Na, Cl–Na, and very low EC). The relation of hydrogeochemistry and altitude is complex and depends on both natural processes (namely, water–rock interaction) and anthropic processes (de-icing operations). The hydrogeophysical survey systematically identified the presence of a pollution plume migrating downstream from roads.