Hydrochemistry of high altitude alpine lakes

The chemical characteristics of 320 Italian alpine lakes are presented and discussed: 38% of them have low ionic concentrations and conductivities below 20 μS/cm; 56% show a conductivity range of 20.1 to 200 μS/cm, and 6% are characterized by higher solute concentrations, up to 34.5 meq/l, with a corresponding maximum conductivity of 1,265 μS/cm.     

Polycyclic aromatic hydrocarbons and their molecular diagnostic ratios in urban atmospheric respirable particulate matter

Atmospheric concentrations of polycyclic aromatic hydrocarbons (PAHs) in Santiago de Chile city were evaluated to study particulate PAHs profiles during cold and spring weather periods. Urban atmospheric particulate matter PM10 was collected using High Volume PM10 samplers. Fifteen samples of 24 h during austral winter and 20 samples of 24 h during spring, 2000 were collected at two sampling sites (North–East and Central areas of the city) whose characteristics were representative of the prevailing conditions. Seventeen PAHs were quantified and total PAHs concentration ranged from 1.39 to 59.98 ng m⁻³, with a seasonal variation (winter vs. spring ratio) from 0.5 to 12.6 ng m⁻³. Molecular diagnostic ratios were used to characterize and identify PAHs emission sources such as combustion and biogenic emissions. Results showed that the major sources of respirable organic aerosol PM10 in Santiago are mobile and stationary ones.     

Multi-year drought frequency analysis at multiple sites by operational hydrology - A comparison of methods

This paper compares two generators of yearly water availabilities from sources located at multiple sites with regard to their ability to reproduce the characteristics of historical critical periods and to provide reliable results in terms of the return period of critical sequences of different length. The two models are a novel multi-site Markov mixture model explicitly accounting for drought occurrences and a multivariate ARMA. In the case of the multisite Markov mixture model parameter estimation is limited to a search in the parameter space guided by the value of parameter λ to show the sensitivity of the model to this parameter. Application to two of the longest time series of streamflows available in Sicily (Italy) shows that the models can provide quite different results in terms of estimated return periods of historic droughts, although they seem to perform more uniformly when it comes to simulate drought-related statistics such as drought length, severity and intensity. The role of parameter selection for the multisite Markov mixture model and of the marginal probability of generated flows in providing results consistent with the characteristics of the observed series is discussed. Both models are applied to the system of sources supplying the city of Palermo (Sicily) and its environs showing the applicability of the newly developed multisite Markov mixture model to medium-to-large scale water resources systems.     

Occurrence and Resistance of Pathogenic Bacteria Along the Tietê River Downstream of São Paulo in Brazil

The load of pathogenic bacteria, their fate and their dangerousness in the Tietê River were assessed along 100 km starting from the city of São Paulo, Brazil. The data were compared with those from two German rivers. High loads of pathogens were found in the Tietê River near the city of São Paulo (Escherichia coli O157:H7, Shigella flexneri, and Shigella boydii), which were absent 30 km downstream of São Paulo. The antibiotic resistances observed in the Tietê river were rather low and decreased after the major input in São Paulo to significantly lower levels about 30 km downstream. While the Brazilian isolates were more susceptible for ampicillin than the German ones, the reverse was observed for gentamycin. For optimal control of infections in humans critical areas where these bacteria survived longer and their elimination mechanisms should be identified as well as the extent and the origin of antibiotic resistance should be determined.     

Petrological And Geochemical Characteristics Of The Granulitic Terrain Of Brejses, Bahia, Brazil

New petrological and geochemical characteristics of the Brejtes region, situated in the south of Bahia, Brazil are discussed. The region forms a part of the most important and extensive granulite facies terrain in Brazil of Archean/Paleoproterozoic age. Five groups of rock types all equilibrated in the granulite facies are identified in this region. They are: i) supracrustal and related rocks, ii) undifferentiated granulites, iii) hornblende bearing enderbite-charnockites, iv) hornblende free enderbite-charnockites, v) charnockites. The first group appears to be the oldest in the region as they form enclaves in the 2.9 Ga old undifferentiated granulites. The third and fourth group are enderbite-charnockites, whose protoliths constitute two series of calc-alkaline rocks, one titanium poor (hornblende free) and another titanium rich (hornblende bearing). U/Pb zircon SHRIMP dates indicate ages of formation at 2.81 Ga (hornblende free) and 2.69 Ga (hornblende bearing) for the two groups. The fifth group of rocks have charnockitic affinity and are present in the center of the Brejtes Dome. These rocks are also have calc-alkaline affinity, but show petrographic and geochemical characteristics distinct from those of other groups. Preliminary geochronological investigations by zircon Pb-Pb evaporation method yielded 2.6 Ga and 2.0 Ga for the charnockites from the inner core of the Brejtes Dome. These age data suggest that the circular structure was formed by the re-fusion of the 2.6 Ga old deep crustal material generating younger charnockites at 2.0 Ga.     

Pyroxenes and olivines as indicators of the petrological evolution of the Ivrea-Verbano basic formation (Italian Western Alps)

Summary Microprobe analyses of olivines, orthopyroxenes and clinopyroxenes of the Ivrea-Verbano basic formation reveal that in the Balmuccia Periodotites (regarded as residual mantle) the phases are more magnesian than in the overlaying ultramafic-mafic series (interpreted as a cumulitic complex formed by fractionation of mantle-derived magma).Pyroxenes underwent sub-solidus re-equilibration. Whole phase (host + exsolved lamellae) compositions give a temperature in the range 946°C–1236°C, compatible with the igneous crystallisation. The compositions of the host phases give temperatures in the range 712°C to 919°C, indicating that the samples did not attain the same degree of equilibrium during the sub-solidus unmixing. The sub-solidus unmixing of the pyroxenes may have occurred either during the superimposed granulite-facies metamorphism or during the slow cooling of the complex intruded into deep crustal levels.

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Pyroxene und Olivine als Indikatoren der petrologischen Entwicklung der basischen Formation von Ivrea-Verbano (Italienische Westalpen)

Zusammenfassung Mikrosondenanalysen von Olivinen, Orthopyroxenen und Klinopyroxenen der basischen Formation von Ivrea-Verbano zeigen, daß in den Balmuccia Peridotiten (die als residuales Mantelmaterial angesehen werden) die Phasen Mg-reicher sind als in den überlagernden ultramafischen bis mafischen Serien (die als Kumulationskomplex gedeutet werden, der durch Fraktionierung eines aus dem Mantel stammenden Magmas gebildet wurde).Die Pyroxene wurden unter Subsolidus-Bedingungen reequilibriert. Die Zusammensetzungen der Gesamtphasen (Wirt + Entmischungslamellen) geben Temperaturen im Bereich von 946–1236°C, was mit einer magmatischen Kristallisation verträglich ist. Die Zusammensetzungen der Wirt-Phasen geben Temperaturen im Bereich von 712–919°C an, was anzeigt, daß die Proben während der Subsolidus-Entmischung nicht denselben Grad der Equilibirierung erreichten. Die Subsolidus-Entmischung der Pyroxene kann entweder während der überlagerten Metamorphose in Granulitfazies oder während der langsamen Abkühlung des in tiefe Krustenschichten intrudierten Komplexes geschehen sein.

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With 4 Figures     

Boundary-layer diffusion modelling: The Gaussian plume approach versus the spectral solution

The equation of turbulent diffusion is solved for a vertical area source within the planetary boundary layer. The traditional Gaussian-plume approach is compared with the spectral solution of the diffusion equation used together with the barotropic boundary-layer model of Lettau and Dabberdt (1970). The results of the numerical computations are presented and the differences between the solutions are discussed.     

Marine debris review for Latin America and the wider Caribbean region: from the 1970s until now, and where do we go from here?

The available literature on marine debris from Latin America and the Wider Caribbean Region was collected and linked, reviewing their methodologies and principal results (quantities, composition and spatial-temporal patterns). The study region comprises 52 coastal countries of which only 14 had registers of works on marine debris. A total of 70 works were available and 69 had their full contents accessed. Brazil dominated the available literature with 70% of the documents. Beaches were the most studied environment, and plastics the prevalent form of contamination in the whole region. The exposure of marine biota (species, type of contact, consequences) was highlighted. The studied region, although still little exploited by this sort of research, shows the same contamination patterns observed world-wide. We also contacted 40 researchers in the area, collecting scientific contributions, opinions and suggestions for improvement of this research field. Further advances and new (urgently needed) lines of research are also discussed.