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271.
Sabino R Veríssimo C Cunha MA Wergikoski B Ferreira FC Rodrigues R Parada H Falcão L Rosado L Pinheiro C Paixão E Brandão J 《Marine pollution bulletin》2011,62(7):1506-1511
Whilst the potential impact on beach users from microorganisms in water has received considerable attention, there has been relatively little investigation into microbial contaminants in sand. Thirty three beaches across Portugal were analyzed during a five year period (2006-2010) to determine the presence of yeasts, pathogenic fungi, dermatophytes, total coliforms, Escherichia coli and intestinal enterococci in sand.Our results showed that 60.4% of the samples were positive for fungi and that 25.2% were positive for the bacterial parameters. The most frequent fungal species found were Candida sp. and Aspergillus sp., whereas intestinal enterococci were the most frequently isolated bacteria. Positive associations were detected among analyzed parameters and country-regions but none among those parameters and sampling period.Regarding threshold values, we propose 15 cfu/g for yeasts, 17 cfu/g for potential pathogenic fungi, 8 cfu/g for dermatophytes. Eighty four cfu/g for coliforms, 250 cfu/g for E. coli, and 100 cfu/g for intestinal enterococci. 相似文献
272.
Ana Margarida Ribeiro Neiva Paulo Bravo Silva Fernando Corfu João Manuel Farinha Ramos 《Chemie der Erde / Geochemistry》2011,71(3):227-245
Seven distinct phases of Variscan two-mica granite are recognized in the Guarda-Sabugal area. They intruded the Cambrian schist-metagraywacke complex, crystallized in the middle crust, and are syn- to late-D3 (309.2 ± 1.8 Ma), late-D3 (304–300 Ma) and late- to post-D3 (299 ± 3 Ma; ID-TIMS ages on zircon and monazite). Two of the granites, G2 and G5, are close in age and have similar Sr, Nd and O isotope characteristics but contrasting whole rock and mineral features and formed by sequential increasing degree of partial melting of a common metasedimentary protolith. During sequential melting Ti, total Fe, Mg, Ca, Zr, Zn, Sr, Ba and REE contents and (La/Yb)N increase and Si and Rb contents decrease, plagioclase becomes richer in anorthite and biotite and muscovite richer in Ti and Mg. Each of these granites evolved subsequently by fractional crystallization of quartz, K-feldspar, plagioclase, biotite and ilmenite, defining separate series G2–G3–G7 and G5–G6 containing late Sn-bearing differentiates. Two other granites G1 and G4 represent distinct pulses of magma with individual fractionation trends for major and trace elements and distinct (87Sr/86Sr)300, ?Nd300 and δ18O values. 相似文献
273.
Catarina Vinagre João Salgado Henrique N. Cabral Maria J. Costa 《Estuaries and Coasts》2011,34(4):663-674
River flow variability is known to influence estuarine production, yet knowledge on its effect upon estuarine food webs dynamics
is still scarce. Stable carbon and nitrogen isotopes were used to assess the effect of river flow in the connectivity and
food web interactions between the two main fish nursery areas of the Tagus estuary. The aims of the present work were to investigate
the seasonal variation in food web structure and the exchange rate of individuals of marine juvenile fish among estuarine
nurseries, to compare the spring of a rainy year (2001) with that of an average year (2000), and to investigate the impact
of the winter floods of 2001. A low level of connectivity was observed for the fish species that use these areas as nurseries.
In low river flow conditions, two isotopically distinct food webs were established in each nursery area. These food webs were
very sensitive to small variations in the freshwater input. Winter floods seem to disrupt the localized food webs that are
established in low river flow periods, leading to the re-establishment of a wider food web. While in rainy years this wide
food web is maintained until spring, in average years the food web undergoes fragmentation into two localized and isotopically
distinctive food webs. The increase in frequency of droughts due to climate change should lower the connectivity of the estuarine
fish nurseries food webs, causing habitat fragmentation and consequent loss in complexity and resilience. 相似文献
274.
Constant shear drained tests (CSD) are probably the most suitable to simulate the strength and deformation behaviour of soils
in slopes under water infiltration conditions or lateral stress relief. This is significant because soil behaviour following
a CSD stress path could differ from that of traditional compression triaxial tests. In this paper, CSD tests on sand following
an alternative procedure are presented and discussed. The modified CSD tests were conducted by increasing the pore water pressure
at a constant rate from one end of the specimen with water free to drain from the opposite end. Among the results from specimens
consolidated at variable initial void ratios and principal stress ratios it was revealed that specimens showed a tendency
to dilate even for loose sands; failure was reached at low axial strains; and a pre-failure type of instability could be identified.
The modified procedure has the potential to provide new insights into the failure mechanisms of slopes under a water infiltration
condition. 相似文献
275.
This paper describes the implementation of process-based models reflecting relative groundwater nitrate vulnerability of the
shallow alluvial Lower Savinja Valley (LSV) aquifer in Slovenia. A spatially explicit identification of the potentially vulnerable
priority areas within groundwater bodies at risk from a chemical point of view is being required for cost-effective measures
and monitoring planning. The shallow LSV unconfined aquifer system consists of high-permeable Holocene and middle- to low-permeable
Pleistocene gravel and sand, with a maximum thickness of about 30 m, mainly covered by shallow eutric fluvisoils or variously
deep eutric cambisoil. The hydrogeological parameters, e.g. the depth to the groundwater, hydrological role of the topographic
slope, etc. usually used in different point count schemes are, in the case of the lowland aquifer and shallow groundwater,
spatially very uniform with low variability. Furthermore, the parametric point count methods are generally not able to illustrate
and analyze important physical processes, and validation of the results is difficult and expensive. Instead of a parametric
point count scheme, we experimentally used the Arc-WofE extension for weights-of-evidence (WofE) modelling. All measurement
locations with a concentration higher than the value of 20 mg NO3
− per litre of groundwater have been considered as training points (173), and the three process-based models generalized output
layers of groundwater recharge (GROWA), nitrate leached from the soil profile (SWAT) and groundwater flow velocity (FEFLOW),
served as evidential themes. The technique is based on the Bayesian idea of phenomena occurrences probability before (prior
probability) and after consideration of any evidential themes (posterior probability), which were measured by positive and
negative weights as an indication of the association between a phenomena and a prediction pattern. The response theme values
describe the relative probability that a 100 × 100 m spatial unit will have a groundwater nitrate concentration higher than
the training points’ limit values with regard to prior probability value. The lowest probability of groundwater nitrate occurrence
is in the parts of the LSV aquifer, which are known as anoxic condition areas with very likely denitrification processes.
The cross-validation of the dissolved oxygen and dissolved nitrate response theme confirmed the accuracy of the groundwater
nitrate prediction. The WofE model results very clearly indicate regional groundwater nitrate distribution and enable spatial
prediction of the probability for increased groundwater nitrate concentration in order to plan the groundwater nitrate reduction
measures and optimize the programme for monitoring the effects of these measures. 相似文献
276.
Chemistry of the Ferraria thermal water, S. Miguel Island, Azores: mixing and precipitation processes 总被引:1,自引:1,他引:0
Maria do Rosário Carvalho António Mateus Jo?o C. Nunes José M. Carvalho 《Environmental Earth Sciences》2011,64(2):539-547
The Ferraria thermal water emerges at the sea level in the Ferraria lava delta (western edge of S. Miguel Island, Azores)
with temperature of ca. 60°C and pH varying between 5.4 and 6.2. It is of sodium chloride type, resulting from ca. 50% seawater
mixing with an acid brackish, at ≈100°C, denoting the presence of significant CO2(g) and the progress of water–rock interactions in open system conditions. The thermal Na–Cl water is strongly enriched with
Sr and Mn and, comparatively, has low concentrations in Al, Fe and As. These elements are removed from the solution as critical
conditions for the formation of several neo-formed mineral phases are gradually attained. Thermodynamic equilibrium calculations
are consistent with this interpretation, showing that the thermal fluid can precipitate Fe3+-(hydr-)oxides, kaolinite and non-crystalline silica. Wells logging show fracture planes and pores fully/partly filled up
with polyphase botryoidal aggregates mostly composed of goethite + ferrihydrite and displaying variable adsorbed contents
of Si, P and As. These neo-formed phases result from the pristine fluid oxidation due to seawater mixing; its precipitation
is easily affected by pH and redox variations of the brackish, due to volcanic gases pressure alterations, and fluid pressure
or flow-velocity oscillation in the fractured aquifer. 相似文献
277.
Allan T. Souza Martina I. Ilarri Joana Campos João C. Marques Irene Martins 《Estuarine, Coastal and Shelf Science》2011
The present study compared the carapace structure of Carcinus maenas in two nearby sites (2 km apart) within Minho estuary, submitted to different physicochemical and ecological conditions (water temperature, pH, crabs’ density and sex ratio). The carapace structure of the carapace and chelae of the crabs presented significant differences between sampling sites (t-test; p < 0.01). The SIMPER analysis revealed that the Weight/CW and Thickness/CW ratios explained all the dissimilarities found among sites. Overall, the male carapace was proportionally thicker at station 2 (t-test; p < 0.01), while the female carapace was proportionally thicker at station 1 (t-test; p < 0.001). A thicker carapace can be advantageous when competing for food or a sexual partner. We hypothetized that, since at station 2, the density of individuals was twice higher than at station 1, it is likely that agonistic encounters are more frequent, thus favouring a thicker carapace. 相似文献
278.
279.
Ariake Bay, Kyushu Island, has recently exhibited environmental degradation in the form of red tides and anoxic bottom water.
To determine the characteristics and regional classification of the copepod community, zooplankton surveys were made throughout
the bay in three cruises each in October 2004, January 2005 and March 2009 by vertical tows of a 0.1-mm-mesh plankton net.
Oithona davisae was the most abundant in January and March, and Microsetella norvegica in October. Cluster analysis revealed that the copepod community from each cruise was generally separated into the inner
to eastern-middle region and the western-middle to mouth region. A SIMPER analysis revealed that dissimilarity between the
groups and similarity within each group were mainly due to the dominant species, but the similarities within the outer-region
group in January and March were mostly contributed by Paracalanus parvus s.l. A non-metric multidimensional scaling with bubble plots of environmental variables and a BIOENV analysis showed that
transparency was more different between the two groups than temperature and salinity. As compared with two similarly sized,
eutrophic bays (Tokyo and Osaka Bays), Ariake Bay differs from Tokyo Bay in the dominance of M. norvegica and from Osaka Bay in the high abundance of O. davisae even in the colder season. The dominant species and the regional classification of the copepod community in the bay were
similar to those in the studies in the 1970s, suggesting that the copepod community has not notably changed during the last
3 decades. 相似文献
280.
Abdelfettah Sifeddine Renato Campello Cordeiro Ana Luiza S. Albuquerque Marcelo Bernardes Bruno Turcq Jorge João Abrão 《Journal of Paleolimnology》2011,45(3):385-396
Elemental and isotopic compositions of organic matter in surficial sediments from five transects across Lagoa do Caçó (Brazil) were analyzed to identify the depth-related processes that affect the production and deposition of sedimentary organic matter in this shallow tropical lake. Each of four transverse transects began at a margin dominated by aquatic macrophytes (Eleocharis), crossed the central deep part of the lake, and terminated in the opposite, macrophyte-dominated margin. In each transect, TOC concentrations, C/N ratios, and δ13C values decreased between 0 and 4 m, whereas δ15N values increased. The variables remained stable in sediment from 4 m water depth to the center of the lake at 10 m. The depth-related patterns reflect differences in both the delivery and the deposition of organic matter in the lake. Organic matter is produced in abundance in the marginal area by emersed and submerged macrophyte vegetation that diminishes with depth and disappears at 4 meters. After the disappearance of macrophytes, organic matter is produced at low rates principally by open-lake phytoplankton. Drawdown of dissolved oxygen is high in the lake margins, but it is low in the oligotrophic open waters of the lake. Preservation of organic matter is consequently better in sediments of the lake margins than in deep waters. The depth-related pattern of organic matter delivery and deposition in the sediments of Lagoa do Caçó, in which water levels are sensitive to groundwater fluctuations, shows that the elemental and isotopic compositions of sediment organic matter can provide a record of changes in the paleohydrology of this and other similar shallow lake systems. 相似文献