Geochemistry and health aspects of F-rich mountainous streams and groundwaters from sierras Pampeanas de Cordoba,Argentina

Symptoms of dental fluorosis have been observed in rural communities located in the Sierras Pampeanas de Córdoba, a mountainous area in Central Argentina. The clinical assessment was performed in the Charbonier Department, where the fluoride (F⁻) intake was determined to be 3.90 ± 0.20 mg day⁻¹ (n = 16). In this community, mild and severe fluorosis reach an incidence of 86.7% (total teeth surface = 636 teeth) among the children population. To determine the origin and distribution of fluorine in natural waters from the Charbonier Department and nearby regions, sampling was performed in the area covering the San Marcos River basin. The obtained results show that F⁻ concentrations vary between ~1 to ~2.5 mg l⁻¹, with an outlier value of 8 mg l⁻¹. The spatial distribution of F⁻ shows that the lowest concentrations are found at the basin’s catchments. Maximum values are located in two sectors of the basin: the Charbonier depression in the eastern part and at the San Marcos village, downstream the main collector, in the western part of the basin. In these two regions, the F⁻ contents in ground- and surface waters are >2.0 mg l⁻¹ and nearly constant. Dissolved F⁻ in natural waters from the study area has its origin in the weathering of F-bearing minerals present in the region’s dominant lithology. The extent of mineral weathering is mostly determined by the residence time of water within the aquatic reservoir. Longer residence times and a major solid–water interaction lead to enhanced release of F⁻. This explains the higher F⁻ concentrations found in basin areas with lower run off. The removal of F⁻ from water appears to occur by neither fluorite precipitation, nor by adsorption. Hence, variations in F⁻ concentrations seem to be more related to regional hydrological conditions.     

Hydrogeochemistry of fluoride in the Quequen river basin: natural pollutants distribution in the argentine pampa

Fluoride pollution is a widespread problem in Argentina, as it is in many areas of the World. Former investigations have demonstrated that the dissolution of volcanic glass disseminated in the loess-like sediments is the main source of fluoride in the Argentine pampas. Nevertheless, fluoride distribution is erratic and the factors controlling it are not yet well-known. A large amount of hydrochemical data collected in the Quequen Grande river catchment is used in order to contribute to the understanding of fluoride distribution and mobility in groundwater in the Argentine pampas. The Quequen Grande river catchment is 10,000 km². It extends between two low hills ranges of Precambrian metamorphic rocks and sedimentary Paleozoic rocks, filled by a thick sequence of Cenozoic sediments, mainly silts and silt-clayed, with sand layers. These sediments form a multilayer phreatic aquifer, which is recharged from precipitation infiltration, discharging through streams directly into the sea. Fluoride concentration in surface water (n = 353) ranges between 0 and 6.5 mg/l, with an average value of 2.14 mg/l. Groundwater concentration (n = 135) is from 0 up to 5.7 mg/l, with an average of 1.84 mg/l. Considering the statistic distribution of fluoride, two groups of samples can be determined. A dominant group between 0 and 3 mg/l, with a mean value around 1.5 mg/l, corresponding to samples widely distributed in the catchment; and a second one group with fluoride contents between 3 and 6 mg/l, corresponding to a smaller area in the central-west border. Two different sources are proposed. Volcanic glass dissolution is responsible for dominant values in the catchment, while the weathering of biotite from the Paleozoic bedrock can be assumed to account for the higher concentrations in the second group.     

Sources and behavior of arsenic and trace elements in groundwater and surface water in the Poopó Lake Basin,Bolivian Altiplano

Water management in semiarid and arid catchments such as the Poopó Lake Basin requires improved understanding of the complex behavior of the various contaminants, which affect the drinking water quality and considered as crucial for sustainable development of the region. Mechanisms of arsenic (As) release in the surface and groundwater were studied. Hydrochemical data for surface water (4 samples) and groundwater (28 samples) were collected in a small watershed in the Poopó catchment at the highland of the Bolivian Andes (Altiplano). All of them show high electrical conductivity values and moderately oxidizing conditions. The surface water contains high concentration of sulfate and the trace elements As, Zn and Pb in the zone affected by acid mine drainage. There is a large variability of the concentration of As and of the trace elements in the groundwater in the five different regions within the Poopó catchment. The metal concentrations sensitive to changes of redox state and results of speciation modeling suggest that As (V) is a predominant aqueous species, which conforms to the prevailing oxidizing conditions in the shallow groundwater environment. Two generalized trends for As distribution were identified in groundwater: (a) high concentrations are found in the arid zone (100–250 μg/L) in the southern (region III) and in the northwestern (region V) regions, and (b) low concentrations (<50 μg/L) are found in the remaining part of the basin (region I, II and IV). However, the spatial distribution within these regions needs to be investigated further. A conclusion from the present study is that there are multiple sources of As as well as other trace elements (such as Cd, Mn and Zn) in the Poopó Lake Basin. Among the sources and the processes which led to the mobility of As and other trace metals in the region are: (a) weathering of sulfide minerals, (b) oxidation of pyrite and/or arsenopyrite in mineralized areas and (c) desorption from hydrous ferric oxide (HFO) surfaces. In non-mining areas, volcanic ash is suggested to be a significant source of As.     

Groundwater flow model, recharge estimation and sustainability in an arid region of Patagonia, Argentina

The Península Valdés, in northeastern Patagonia, Argentina, is characterised by its arid climate and the lack of perennial watercourses; thus, all economic activities depend on the groundwater resources. Water demand is mainly associated with tourism, which is centralised in Puerto Pirámides and supplied by a water desalination plant, and to sheep farming, supplied by the local aquifer. Due to the exponential growth of tourism, the government is planning to exploit groundwater and convey it by aqueduct to the abovementioned locality. The objectives of this study were to corroborate the conceptual geohydrological model, to develop a mathematical model to simulate the response of the aquifer to different scenarios, and to assess the incidence of water input into the system as a variable—a function that poses difficulties in the models for arid regions. The Visual Modflow 4.1 code was used, calibrating it in trial-and-error mode, changing the recharge and hydraulic conductivity parameters with different variants in the recharge zone and in the inclusion or exclusion of the evapotranspiration module. Results indicate the importance of the recharge analysis by treating rainfall at daily time steps. The adjusted model was exposed to four scenarios with variations in water input and in output by pumping. It can be concluded that under different input conditions, but with a controlled extraction, the system responds in a sustainable manner.     

Fluid inclusion studies in datolite of low grade metamorphic origin from a Jurassic pillow basalt series in northeastern Hungary

The Jurassic pillow basalt blocks in the Szarvask? Unit in the SW-Bükk Mountains are incorporated into an accretionary mélange of Cretaceous age which had been displaced from the Dinarides to NE-Hungary during the Alpine-Carpathian collision. The pillow basalt series is a part of an incomplete remnant of an ophiolite-like sequence from which ultramafic units and sheeted dikes are almost completely absent. At the studied Egerbakta quarry, closely packed pillow, pillow fragmented hyaloclastite breccia and peperitic facies of submarine basaltic volcanism were recognized. Peperitic facies was formed by local admixture of unconsolidated siliciclastic sediment into the basaltic lava. Basaltic pillows contains short and thin prehnite-chlorite-carbonate-quartz veins formed during the interaction of seawater with the cooling lava, as well as cross-cutting datolite-prehnite-quartzchlorite-albite bearing veins. Calcite in the short cooling cracks crystallised from upheated seawater at around 160°C temperature and 0.5?C0.6 kbar pressure (water depth of about 5?C6 km). Datolite precipitations in veins can be classified into at least three different textural-morphological types but all of them contain methane bearing primary fluid inclusion assemblages, with variable methane/water ratios, suggesting an inhomogeneous entrapment from a heterogeneous aqueous-carbonic fluid. End member primary fluid inclusions contain aqueous liquid with methane rich vapour phase and apparently methane only inclusions characterized by liquid phase on room temperature. A combination of results from fluid inclusion microthermometry, Raman spectroscopy (used not only for phase identification but also for determination of salinities) and temperatures calculated from chlorite compositions, show that the precipitation of datolite had taken place from low salinity (0.2?C2 NaCl equiv. mass%) aqueous-methane fluids under increasing temperature and pressure (from 160 to 210°C, and from 0.6 to 1.1 kbar) conditions. The elevated pressures and temperatures in comparison to the submarine hydrothermal processes suggest that the datolite bearing mineral parageneses had been formed during the progression of Alpine very low grade metamorphic processes.     

The ionosphere: effects,GPS modeling and the benefits for space geodetic techniques

The main goal of this paper is to provide a summary of our current knowledge of the ionosphere as it relates to space geodetic techniques, especially the most informative technology, global navigation satellite systems (GNSS), specifically the fully deployed and operational global positioning system (GPS). As such, the main relevant modeling points are discussed, and the corresponding results of ionospheric monitoring are related, which were mostly computed using GPS data and based on the direct experience of the authors. We address various phenomena such as horizontal and vertical ionospheric morphology in quiet conditions, traveling ionospheric disturbances, solar flares, ionospheric storms and scintillation. Finally, we also tackle the question of how improved knowledge of ionospheric conditions, especially in terms of an accurate understanding of the distribution of free electrons, can improve space geodetic techniques at different levels, such as higher-order ionospheric effects, precise GNSS navigation, single-antenna GNSS orientation and real-time GNSS meteorology.     

Energy use, climate change and folk psychology: Does sustainability have a chance? Results from a qualitative study in five European countries

Citizens’ support for policies that aim to curb carbon emissions and energy use is often seen as informed by their values, attitudes and perceptions of the environmental problem in question. We argue that we also need to understand how people conceptualise policies and the governance approaches underpinning them to be able to judge the likely acceptance of policy change.In this study, we draw on qualitative interviews (n = 202) from five European countries to explore citizens’ views on governance approaches to stimulate behavioural change in the field of resource use, including regulations, price changes, collective action, technological change and education.We found that many of our interviewees referred to generalised characteristics of humankind and contemporary society to back up their arguments for or against specific governance approaches. In particular, many interviewees concurred that people in general were so self-centred, driven by habit and money- and consumption-oriented that only strict regulations, drastic price changes and technological innovation could possibly achieve widespread behavioural change. As a consequence, such ‘folk psychologies’ can have substantial impact not only on public acceptance, but also on the success of policy measures that aim to reduce citizens’ resource use.     

Evaluation of heavy metals and arsenic speciation discharged by the industrial activity on the Tinto-Odiel estuary, SW Spain

This study reports the annual amount of heavy metals discharged by industrial activity into the estuary of the Ría of Huelva (SW Spain). The findings showed that the discharged metals found in highest amounts were Fe (11 t y⁻¹), Zn (3.4 t y⁻¹) and Mo (0.88 t y⁻¹). There were other metals with high pollutant charge, such as Ti (232 kg y⁻¹), As (228 kg y⁻¹), Ni (195 kg y⁻¹), Pb (100 kg y⁻¹), Cr (39 kg y⁻¹) and Cd (33 kg y⁻¹). These results were compared with pollutants transported via the Tinto and Odiel rivers from abandoned mining activities in the Iberian Pyrite Belt (IPB), and it was deduced that the amounts spilled exclusively by industries were less than 1% in relation to the total discharge. Hence, the treatment of residues from the IPB should be the priority goal to improve water quality in the estuary.     

Probabilistic risk assessment of common booster biocides in surface waters of the harbours of Gran Canaria (Spain)

The presence of booster biocides in the aquatic environment has been associated with a risk to non-target species due to their proven toxicity. The aim of the present study was to determine the spatial and temporal distribution of common booster biocides in different harbours of the island of Gran Canaria (Spain) and evaluate, by means of a probabilistic risk assessment (PRA), the ecological risk posed by these compounds. With these objectives, a monitoring campaign was conducted between January 2008 and May 2009, collecting a total of 182 seawater samples. Four common booster biocides (TCMTB, diuron, Irgarol 1051 and dichlofluanid) were monitored. Diuron levels ranged between 2.3 and 203 ng/L and Irgarol 1051 between 2.4 and 146.5 ng/L. The ecological risk associated with these levels was always low, however, with probabilities of exceeding the 10th percentile of autotroph toxicity below 3.5%.     

Ecological quality assessment of small estuaries from the Portuguese coast based on fish assemblages indices

The importance of establishing the ecological quality of estuarine systems has been widely acknowledged and led to the development of several fish community-based multimetric indices. Nevertheless, a question rose about the accuracy of these tools when natural disturbance is acting upon the organization of the systems’ communities. Four multimetric indices were used to examine their ability to differentiate the ecological status of five small estuarine systems (southern Portugal), and also to test if they reflected the level of anthropogenic pressures. Fish assemblages from Mira, Odeceixe and Aljezur (in the Southwest coast), Gilão and Bensafrim (in the South coast) estuaries were sampled seasonally for one year, and anthropogenic sources of pressure were identified and quantified. We found that although the applied indices provided information on ecological condition differentiation among systems, they are unable to explain different classes of ecological status in systems with equivalent pressure levels.