Laboratory simulation of interplanetary ultraviolet radiation (broad spectrum) and its effects on Deinococcus radiodurans

The radiation-resistant bacterium Deinococcus radiodurans was exposed to a simulated interplanetary UV radiation at the Brazilian Synchrotron Light Laboratory (LNLS). Bacterial samples were irradiated on different substrates to investigate the influence of surface relief on cell survival. The effects of cell multi-layers were also investigated. The ratio of viable microorganisms remained virtually the same (average 2%) for integrated doses from 1.2 to 12 kJ m⁻², corresponding to 16 h of irradiation at most. The asymptotic profiles of the curves, clearly connected to a shielding effect provided by multi-layering cells on a cavitary substrate (carbon tape), means that the inactivation rate may not change significantly along extended periods of exposure to radiation. Such high survival rates reinforce the possibility of an interplanetary transfer of viable microbes.     

Macrofauna associated to Mycale microsigmatosa (Porifera, Demospongiae) in Rio de Janeiro State, SE Brazil

The macrofauna (endo- and epi-biotic) associated to the sponge Mycale (Carmia) microsigmatosa Arndt, 1927 was studied at three sites in Rio de Janeiro State, Brazil (Arraial do Cabo, Niterói, and Rio de Janeiro). A total of 2235 individuals (over 1 mm long) of 75 invertebrate species were found associated to 19 specimens of the sponge. The most abundant and diverse taxa were the crustaceans (83%, 31 spp.), polychetes (10%, 18 spp.), and molluscs (3.7%, 15 spp.). Cnidarians, platyhelminthes, ascidians, echinoderms, pycnogonids, bryozoans, and sponges were also represented. Amphipod crustaceans were the dominant group, comprising 61% of all individuals collected. Species richness and abundance of associated fauna were highly correlated with sponge volume, but diversity and evenness were not. The site of collection influenced the species composition of the fauna associated to M. microsigmatosa but did not change significantly its diversity, abundance, richness, and dominance patterns of higher taxa. Pregnant females and juvenile stages of 29% of the species associated, including crustaceans, molluscs, echinoderms, and pycnogonids were frequently found inside M. microsigmatosa. Although many of these organisms do occur and reproduce in other habitats outside the sponge as well, M. microsigmatosa is also important for their reproduction and survivorship, thus contributing for the maintenance of biodiversity in Southwestern Atlantic sublittoral rocky shores.     

Hydrogeochemical and Flow Modeling of Aquitard Percolation in the Cariri Valley-Northeast Brazil

Flow modeling and hydrogeochemical inversion calculations were performed on the aquifer systems of the Crato-Juazeiro Graben in the Araripe Sedimentary Basin of the Cariri Valley, Northeast Brazil, in order to assess aquifer interconnections through an aquitard of the Araripe Plateau. Steady state hydraulic head numeric calculations with the finite difference method used Modflow software with hydrologically based boundary conditions and a piezometric surface as initial condition. Hydrogeochemical inversion with PHREEQC was performed for two water samples representing typical initial and final waters along the flow path. Flow simulation shows that approximately 20% of all recharge water from the superior aquifer system passes through the Santana aquitard reaching the middle aquifer system. Quantification of mineral dissolution/precipitation processes, ion exchange and microbiological redox reactions taking place in the aquifer systems also indicates hydraulic interconnection of the superior and middle aquifer systems through the Santana aquitard.     

Analysis of seismic reflection data as a tool for the seismotectonic assessment of a low activity intraplate basin – the Lower Tagus Valley (Portugal)

The Lower TagusValley is located in the Lower TagusSedimentary Basin. Occurrence ofearthquakes in the area indicates thepresence of seismogenic structures at depththat are still deficiently known due to athick Cenozoic sedimentary cover. It isusually assumed that regional M = 6–7earthquakes are generated by the LowerTagus Valley fault. However, this structurehas never been characterised, and there isevidence for the presence of other faultsthat have the potential of generating largeseismic events. The hidden character ofmany of the structures in the Lower TagusBasin necessitates the use of indirectmethodologies for their study. Availableseismic reflection lines acquired for oilexploration in the Lower Tagus Valleyregion were thus examined, with emphasis onthe recognition of faults displacing theCenozoic and particularly the youngergeological units. The foreseen complexityof the basin structure was confirmed.Evidence for a continuous `Lower TagusValley fault' is absent. Instead, N-S toNNE-SSW trending, en echelon,sub-vertical and reverse faults showingsignificant post-Miocene offsets, linked bytransverse (NW-SE) faults that accommodatelarge displacements, were recognised in theseismic sections that cross the Tagusvalley. These faults range in length from10 km to a maximum of ca. 40 km, leading toan estimation of 6.2–6.9 maximum credibleearthquake magnitudes, which fall in themagnitude range of the regional historicalseismicity.     

Stochastic delineation of capture zones: classical versus Bayesian approach

A Bayesian approach to characterize the predictive uncertainty in the delineation of time-related well capture zones in heterogeneous formations is presented and compared with the classical or non-Bayesian approach. The transmissivity field is modelled as a random space function and conditioned on distributed measurements of the transmissivity. In conventional geostatistical methods the mean value of the log transmissivity and the functional form of the covariance and its parameters are estimated from the available measurements, and then entered into the prediction equations as if they are the true values. However, this classical approach accounts only for the uncertainty that stems from the lack of ability to exactly predict the transmissivity at unmeasured locations. In reality, the number of measurements used to infer the statistical properties of the transmissvity field is often limited, which introduces error in the estimation of the structural parameters. The method presented accounts for the uncertainty that originates from the imperfect knowledge of the parameters by treating them as random variables. In particular, we use Bayesian methods of inference so as to make proper allowance for the uncertainty associated with estimating the unknown values of the parameters. The classical and Bayesian approach to stochastic capture zone delineation are detailed and applied to a hypothetical flow field. Two different sampling densities on a regular grid are considered to evaluate the effect of data density in both methods. Results indicate that the predictions of the Bayesian approach are more conservative.     

Adaptations of microphytobenthos assemblages to sediment type and tidal position

Tagus intertidal microphytobenthos (MPB) assemblages were characterized over a wide range of sediment type and tidal height and the possible effects of these variables on MPB spatial distribution and photo-adaptation mechanisms were investigated. Two transects with six different sediment type and different tidal height sites were sampled once every two months from 2002 to 2004. Upper shore and sandy sites showed higher chlorophyll a (chl a) content, with sandy sediments showing a biomass peak in late winter–early spring, and muddy sites showing no obvious seasonal pattern. Stepwise multiple linear regressions showed that only SiO₂, tidal height and sediment particle size <63 μm were significant variables (p<0.05), explaining 50% of MPB biomass spatial–temporal variability. However, when data were separated by transect, only tidal height remained significant at both transects. Sandier sediments exhibited higher zeaxanthin/chl a and lower fucoxanthin/chl a ratios characteristic of a mixed cyanobacteria/diatom assemblages, showing an alternate seasonality with cyanobacteria increasing in summer and diatoms dominating in spring. Diatom biofilms showed contrasting features depending on the sediment type. Epipsammic diatoms were small with an average length of around 10 μm, while epipelic diatoms showed a wider size range with size distribution peaks at 10–15 μm, 25–35 μm and >60 μm. Epipelic biofilms showed evidence of being low light-acclimated (high fucoxanthin/chl a) and of photo-regulating by vertical migration movements (presence of endogenous vertical rhythms and lower diatoxanthin/diadinoxanthin). Epipsammic biofilms showed higher diatoxanthin/diadinoxanthin ratios and no vertical migration rhythms. Thus, the two diatom biofilm types had distinct strategies to photo-regulate: epipelic diatoms using vertical migration to position themselves at the sediment depth of optimum light conditions, and epipsammic diatoms using the xanthophyll cycle to photo-regulate. Further studies comparing epipsammic and epipelic assemblages are necessary to better understand MPB photo-regulation mechanisms.     

Associations between outdoor air quality and birth weight: a geostatistical sequential simulation approach in Coastal Alentejo,Portugal

Several environmental health studies suggest birth weight is associated with outdoor air pollution during gestation. In these studies, exposure assignments are usually based on measurements collected at air quality monitoring stations that do not coincide with health data locations. So, estimated exposures can be misleading if they do not take into account the uncertainty of exposure estimates. In this article we conducted a semi-ecological study to analyze associations between air quality during gestation and birth weight. Air quality during gestation was measured using a biomonitor, as an alternative to traditional air quality monitoring stations data, in order to increase spatial resolution of exposure measurements. To our knowledge this is the first time that the association between air quality and birth weight is studied using biomonitors. To address exposure uncertainty at health locations, we applied geostatistical simulation on biomonitoring data that provided multiple equally probable realizations of biomonitoring data, with reproduction of observed histogram and spatial covariance while matching for conditioning data. Each simulation represented a measure of exposure at each location. The set of simulations provided a measure of exposure uncertainty at each location. To incorporate uncertainty in our analysis we used generalized linear models, fitted simulation outputs and health data on birth weights and assessed statistical significance of exposure parameter using non-parametric bootstrap techniques. We found a positive association between air quality and birth weight. However, this association was not statistically significant. We also found a modest but significant association between air quality and birth weight among babies exposed to gestational tobacco smoke.     

Geophysical analysis of Catalão I alkaline–carbonatite complex in Goiás,Brazil

The Catalão I alkaline–carbonatite complex, which is located in Central Brazil, is one of the main producers of niobium and phosphates in the world. It has been intensely studied geologically and geochemically for its economic potential. This work presents a geophysical analysis over this complex, identifying its behaviour in the subsurface and in portions that have not been explored yet. Different geophysical methods and techniques were applied to achieve the most reliable results possible: at the surface, through radiometric, geological, and topographic data, and at depth, by geological, magnetic, and gravimetric data. The analysis was successfully completed with inversions of gravity and magnetic data that resulted in quite similar models, both in volume and shape. Their density and magnetic susceptibility contrasts were consistent with the expected dunite–pyroxenite lithology from the original mafic intrusion and indicated (by exclusion) the volume of the carbonatite body, which along with the known contents of phosphates and niobium allowed an indirect estimate of the reserves and resources of the complex.     

Removal of selected heavy metals from MSW fly ash by the electrodialytic process

This paper aims to assess the applicability of the electrodialytic remediation technique for the removal of zinc, lead, copper and cadmium from municipal solid waste (MSW) incinerator fly ash. A broad range of experimental conditions were studied including current densities, remediation times, use of assisting agents and cell design.

Several operational problems were identified during the electrodialytic experiments, among which are formation of precipitates, dryness of sample and partial dissolution of sample creating preferential pathways for the electric current. These problems may explain the low remediation efficiencies obtained.

Comparison between experiments showed that generally the use of Na-gluconate as assisting agent leads to better results than distilled water. Increasing the concentration of the assisting agent also results in higher removals.