Hydrogeochemistry of Lake Gallocanta (Aragón,NE Spain)

Lake Gallocanta has undergone drastic changes during the last thirteen years. Water level changed from a high level (Z_max = 2 m) to total dryness in 1985. From 1986 to 1988 slow refilling occurred. The water volume fluctuations have been studied in relation to climatic variations recorded for that period. Variations in the major dissolved ions were related to water volume fluctuations from data at two different stages, one corresponding to the drying phase and another to the refilling phase. Mineralogical composition of the salts precipitated at different stages was examined by X-ray diffraction. Interstitial water and mineralogical composition of recent sediments were also studied along a transect through the lake.The water column decrease from 1977 to 1985 is related to decreasing annual rainfall (500-250 mm respectively). The refilling in 1986–1988 is due to high annual rainfall (537 mm). In addition to these fluctuations, seasonal changes of the water level between 20 and 50 cm occurred every year.Gallocanta is a Na-Mg-Cl-(SO₄) type lake. During the drying period a typical salt enrichment occurs with linear relationships between TDS, Cl, Na and K. Alkalinity is linearly correlated with Ca at relatively low salinities. As salinity increases a linear relationship between Ca and SO₄ is observed. Minerals formed from the brine are halite, bischofite, epsomite, hexahydrite, mirabilite, gypsum, aragonite, calcite and dolomite. The molar ratio Mg/Ca of the interstitial water changes from 1.5 along the shorelines, where calcite and aragonite precipitate, to 40 in the center of the lake. Sediment cores from the central part of the lake show aragonite in the top layers, magnesian calcite and low proportions of quartz and illite, while at 20 cm depth a high proportion of gypsum is present. In contrast, cores from the shore of the lake are mainly composed of low magnesium calcite in the top layers and low magnesium calcite together high magnesium calcite and dolomite between 30 and 70 cm depth. Gypsum deposits only occur in significant proportions at 80–100 cm depth.The refilling process showed relationships between volume and salt concentration following the Langbein model. The salt mass in solution decreased about 50% from the drying to the refilling phase. However, Mg content decreased about 70 % for the same period, suggesting a contribution of this element to the dolomite formation.     

Spatial heterogeneity of macrophytes in Lake Gallocanta (Aragón,NE Spain)

The spatial distribution of macrophytes (Ruppia drepanensis) Tineo and Lamprothamnium papulosum (Wallr.) J. Gr. was studied along transects perpendicular to the shoreline in Lake Gallocanta (Aragón, NE Spain) in 1988 and 1990. In the shallow zone, a gradient from the shoreline to offshore waters was clear: Small R. drepanensis plants were the only colonizers of nearshore waters affected by wave action and desiccation. R. drepanensis and L. papulosum coexisted at intermediate depths in the shallow zone. L. papulosum reached higher biomasses than R. drepanensis in the deepest parts of the shallow zone. In the deepest zone of the lake, stands of the two species did not overlap. Individual plants of R. drepanensis occured patchily within a sparse prairie of L. papulosum.This spatial pattern was observed at different lake levels, suggesting that macrophytes are adapted to fluctuations of environmental conditions. In very shallow water the macrophytes decay as indicated by negative net production and low chlorophyll a/chlorophyll b and plant K⁺ concentration/water K⁺ concentration ratios.     

The Aragonian and Vallesian high-resolution micromammal succession from the Calatayud-Montalbán Basin (Aragón,Spain)

We present an updated taxonomy and faunal distribution of the micromammal fossil record from the Aragonian and Lower Vallesian of the Calatayud-Montalbán Basin. The analysed record includes the orders Rodentia, Eulipotyphla, and Lagomorpha. The pattern of species turnover shows seven major faunal events, which are correlated with major climate changes based on marine stable oxygen and carbon isotope records. Episodes δ¹⁸O Mi-2 and Mi-3 are significantly correlated with major micromammal turnover at the boundaries between the Lower and Middle Aragonian and the Middle and Upper Aragonian, respectively. Our results support the existence of a selective turnover during the Aragonian and Lower Vallesian.     

Adiposity, physical activity, and physical fitness among children from Aragón, Spain

Objective: The main purpose of this study was to determine the relationship between physical activity (PA) levels and adiposity. The secondary purpose was to assess the effect of physical fitness and living area on adiposity. Research Methods and Procedures: A cross‐sectional study was carried out in a regional representative sample of 1068 children 7 to 12 years of age. Anthropometric and physical fitness values (including BMI, aerobic capacity, strength levels, velocity assessment, and flexibility) were measured in all children. Results: The prevalence of being overweight and obese in the entire sample was 31% and 6%, respectively. No difference between urban and rural children was found. The proportion of boys who were classified as overweight and obese was similar in physically active and sedentary (non‐physically active) groups. However, physically active girls tended to show lower obesity prevalence compared with their sedentary counterparts (p = 0.06). In girls, the sum of the 6 skinfolds thickness (SSF) measurements was lower in the physically active group when compared with the non‐physically active group (p < 0.05); however, this effect was not observed in boys. Multiple regression analysis revealed that the level of physical activity (PA) had a significant effect on BMI and SSF in boys but not in girls, while maximal oxygen uptake (Vo _2max) was significantly related to adiposity in both sexes. Discussion: Regular participation in at least 2 hours per week of sports activities on top of the compulsory education program is associated with better physical fitness and lower whole body adiposity. In the children included in our study, among all physical fitness variables, Vo _2max showed the strongest relationship with BMI and fat mass assessed by means of skinfold measurements.     

Benthic invertebrate assemblage in Samborombón River (Argentina,S. America), a brackish plain river

The spatial and temporal differences in the structure and composition of benthic invertebrates were studied at three sites of the Samborombón River, which is an important tributary of the Río de la Plata Estuary (Argentina), having a low slope and brackish drainage. Biological samples were taken during each season. Physico-chemical variables were measured to determine their association in the benthic fauna distribution. Site 1, in the headstream, was characterized by freshwater Pampean organisms; site 2 showed the highest density, taxa diversity, and richness; brackish species, e.g., Laeonereis culveri, were found here. Site 3, close to the Samborombón Bay, was characterized by an unstable taxonomic composition that is strongly influenced by the estuary. The lowest density and taxonomic diversity of organisms were registered and distinguished by estuarine species. The multivariate method (redundancy analysis) showed the benthic groups having an important spatial variability, superimposed on the temporal variability, associated with the salinity gradient of the river.     

Pollen content study of the lower atmosphere in León (Spain) by use of a tethered balloon

This study was undertaken in order to understand thebehaviour of airborne pollen grains, namely therelationship between their concentrations andconcomitant meteorological parameters, at differentaltitudes (ground level, 200, 400 and 600 m) of thelower atmosphere and its daily variations over onesite (the experimental farm of the University ofLeón). The experimental design involved a tetheredballoon (2.25 m³), an ADAS remote meteorologicalstation and an original radio controlled three headedpollen and spore sampler (called GABIS) using theRotorod design. Each head sampled a differentaltitude, while two control samples were taken atground level. Twenty-one takeoffs could be realized inthe 5 weeks period between end of May and end of June1997. Sampling was done early in the morning and sampling time at each altitudewas of 15 minutes. Results show that 45 differenttypes of pollen grains could be collected at this timeof the year and that significant variations could beobserved in the behaviour of the pollen cloud on a dayto day basis, probably because of differentmeteorological situations. Contrary to what isgenerally believed, pollen was in most cases moreabundant at higher altitude – on average by 30% ascompared to ground level – making evident anaerobiological layer of transport at about 500 m aboveground. This was especially the case for trees (Quercus and Castanea). The atmosphere MixingRatio was the most explicative factor at 200 m, whiletemperature dominated significance analysis at both400 and 600 m.     

Spatial and temporal variability of ground-level ozone in Castilla-León (Spain)

Ozone is a secondary air pollutant that has received extensive attention in the literature, mainly because of the adverse effects that exposure to it can cause, particularly in vegetation during the growing season. Because meteorological conditions strongly influence the efficiency of photochemical processes leading to ozone formation and destruction, ground-level ozone air pollution is currently being considered as a regional-scale phenomenon rather than a local one. This role of O₃ as a regional-scale pollutant often implies the handling of large data sets in order to obtain information about its spatial and temporal variability patterns over a given broad region. Rotated principal component analysis (RPCA) is known to be one of the most powerful mathematical tools that can be used to achieve this aim. RPCA was applied in this paper to the summer and winter hourly time series of ground-level O₃, concentrations recorded during 2 consecutive years (1996–1997) at 26 urban and suburban sites in Castilla-León (Spain). This procedure permitted the identification of different subregions where O₃ concentrations show different spatio-temporal variability patterns. These variability patterns are mainly associated with the interaction of regional-level meteorological and anthropogenic factors. Some differences between winter and summer patterns were also found. Received: 5 April 1999 / Revised: 27 December 1999 / Accepted: 27 December 1999     

Airborne pollen and spores of León (Spain)

A qualitative and quantitative analysis of airborne pollen and spores was carried out over 2 years (from September 1987 to August 1989) in the city of León. Slides were prepared daily using a volumetric pollen trap, which was placed on the Faculty of Veterinary Science building (University of León) 12m above ground-level. Fifty-one pollen types were observed; the most important of these were: Cupressaceae during the winter,Pinus andQuercus in spring, and Poaceae, Leguminosae and Chenopodiaceae in the summer. The results also showed the existence of a rich mould spore assemblage in the atmosphere. The group of Amerospores (Penicillium, Aspergillus andCladosporium) as well as Dictyospores (Alternaria) were the most abundant;Puccinia was common in the air in August. Fluctuations in the total pollen and spores m³ of air were compared with meteorological parameters (temperature, relative humidity and rainfall). From the daily sampling of the atmosphere of León, considering the maximum and minimum temperature and duration of rainfall, the start of the pollen grain season was observed generally to coincide with a rise in temperature in the absence of rain.     

Daily and seasonal variations ofAlternaria andCladosporium airborne spores in León (North-West, Spain)

The spores ofAlternaria andCladosporium are present throughout the year in the atmosphere of León (NW Spain), although they show an important seasonal variation. To understand the relationship between the number of spores and climatic factors,Alternaria andCladosporium spores counts for January 1994 to December 1995 were examined by means of correlation analyses. The results of weekly samples of both years showed that the spores concentration of two taxa are significantly and positively correlated with maximum and minimum temperature and sunshine hours and negatively with relative humidity. The statistical analysis of daily samples generally showed the same results. In the hourly distribution of spore concentrations we can see a similar behaviour ofAlternaria andCladosporium, with most spores collected in the 12–14 h period.