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81.
Mangialajo L Ruggieri N Asnaghi V Chiantore M Povero P Cattaneo-Vietti R 《Marine pollution bulletin》2007,55(1-6):30-41
The assessment of the ecological status, as required by the Water Framework Directive (WFD), plays an important role in coastal zone management, but only a small number of ecological indices are applicable on rocky bottoms. In this study, we apply a previously defined ecological quality index based on the cartography of littoral and upper-sublittoral rocky-shore communities (CARLIT), based on the sensitivity of algae dominated communities to anthropogenic impacts along a moderate urban gradient. We also apply this index in four Marine Protected Areas (MPAs), proposed as reference sites at a regional scale. After comparing the outputs with water variables and other quality indices, we can affirm that (1) the CARLIT index is suitable to detect different kinds of anthropogenic pressures, that (2) the choice of proper reference sites is a focal point in the fulfilment of the WFD (Water Framework Directive) and that (3) historical data are important to define reference conditions and the degradation of ecological status. 相似文献
82.
Ballesteros E Torras X Pinedo S García M Mangialajo L de Torres M 《Marine pollution bulletin》2007,55(1-6):172-180
Macroalgae is a biological key element for the assessment of the ecological status in coastal waters in the frame of the European Water Framework Directive (WFD, 2000/60/EC). Here we propose a methodology for monitoring water quality based on the cartography of littoral and upper-sublittoral rocky-shore communities (CARLIT, in short). With the use of spatial databases, GIS, and available information about the value of rocky-shore communities as indicators of water quality, it is possible to obtain an environmental quality index representative of the ecological status of rocky coasts. This index, which completely fulfils the requirements of the WFD, is expressed as a ratio between the observed values in the sector of shore that is being assessed and the expected value in a reference condition zone with the same substrate and coastal morphology (Ecological Quality Ratio, EQR). The application of this index to the coast of Catalonia (North-Western Mediterranean) is presented. 相似文献
83.
César Viseras Juan Fernández Fernando García-García Jesús M. Soria María Luisa Calvache Pedro Jáuregui 《Environmental Geology》2009,56(7):1353-1369
An analysis has been made of sedimentary systems involved in the rapid silting of a reservoir constructed in 1974 in Alhama
de Granada (S. Spain); in only 30 years the storage capacity of the reservoir has shrunk by 80% and its perimeter has decreased
by 64%. A study of sediment lithofacies identified in a series of shallow trenches and of georadar facies identified in a
series of almost 900 m lines of ground penetrating radar (GPR) images, together with a survey of surface geology, has identified
3 alluvial systems (2 transversal systems and a longitudinal system) whose deltas have filled in the reservoir. Thus, there
are three phases in the evolution of the reservoir siltation: (1) an initial stage (1974–1977) typified by northward progradation
of the longitudinal river delta of about 100 m year−1 and an eastward progradation of the transversal system delta of about 20 m year−1; (2) an intermediate stage (1977–1984) in which the longitudinal river delta progradation slowed to 25 m year−1 and the axial drainage became obstructed due to the considerable eastward progradation of the transversal delta; and (3)
a final phase (1984–present) in which there have been few changes in the areal distribution of the deltas apart from a southeastward
expansion of the transversal delta. Generally, aggradational growth patterns (vertical accretion) have dominated in this final
phase. The lithology of the source area, the slope and precipitation distribution has a significant effect not only on the
sediment supply, but also indirectly on the creation of accommodation space and on the evolution of stratal growth patterns. 相似文献
84.
Luca Gasperini Enrico Bonatti Sonia Albertazzi Luisa Forlani Carla A. Accorsi Giuseppe Longo Mariangela Ravaioli Francesca Alvisi Alina Polonia Fabio Sacchetti 《地学学报》2009,21(6):489-494
Cheko, a small lake located in Siberia close to the epicentre of the 1908 Tunguska explosion, might fill a crater left by the impact of a fragment of a Cosmic Body. Sediment cores from the lake’s bottom were studied to support or reject this hypothesis. A 175‐cm long core, collected near the center of the lake, consists of an upper ~1 m thick sequence of lacustrine deposits overlaying coarser chaotic material. 210Pb and 137Cs indicate that the transition from lower to upper sequence occurred close to the time of the Tunguska Event. Pollen analysis reveals that remains of aquatic plants are abundant in the top post‐1908 sequence, but are absent in the lower pre‐1908 portion of the core. These results, including organic C, N and δ13C data, suggest that Lake Cheko formed at the time of the Tunguska Event. 相似文献
85.
Erik Velasco Shelley Pressley Rasa Grivicke Eugene Allwine Luisa T. Molina Brian Lamb 《Theoretical and Applied Climatology》2011,103(3-4):501-517
The parameterization of the energy balance from a residential and commercial neighborhood of Mexico City was investigated using direct measurements of radiative and heat fluxes carried out during the MILAGRO/MCMA-2006 field campaign as a reference. The measured fluxes were used to evaluate different models of the energy balance based on parameterizations that require standard meteorological observations: ambient temperature, relative humidity, atmospheric pressure and cloudiness. It was found that these models reproduce with reasonable accuracy the diurnal features of the radiative and heat fluxes. The largest differences between modeled and observed fluxes correspond to the incoming longwave radiation, mainly due to errors in the cloudiness data. This paper contributes to the understanding of the energy partitioning in (sub)tropical urban environments, particularly in the developing world, where energy balance models have not been evaluated. 相似文献
86.
Cohu S Thibaut T Mangialajo L Labat JP Passafiume O Blanfuné A Simon N Cottalorda JM Lemée R 《Marine pollution bulletin》2011,62(12):2681-2691
To study environment characteristics favoring the toxic benthic dinoflagellate Ostreopsis cf. ovata, a survey was conducted in Monaco (NW Mediterranean Sea), in summers 2007 and 2008. Epiphytic and planktonic blooms occurred almost simultaneously and a high variation of abundances at low spatial scales was observed. An early and very marked bloom occurred in 2007, compared to a later and less abundant development in 2008. These distinct patterns in bloom timing corresponded with very different hydroclimatic scenarios in 2007 (hot spring and relatively cold summer) and 2008 (standard year compared to the median year profile estimated with data from 1995 to 2008). No clear impacts of summer seawater temperature, rainfall or nutrient concentrations were evident. Strong wind may favor the dispersal of benthic and planktonic cells. Our study suggests that further investigations are needed to examine the potential role of Ostreopsis nutritional mode (i.e. autotrophy vs. mixotrophy). 相似文献
87.
88.
Adriana Leonhardt Maria Luisa Lorscheitter 《Journal of South American Earth Sciences》2010,29(2):454-463
The palaeoenvironmental history has been studied based on palynology of a sedimentary profile from the Alpes de São Francisco bog (29°29′35′′S, 50°37′18′′W), São Francisco de Paula municipality, Rio Grande do Sul eastern Plateau, extreme Southern Brazil. The results indicate a regional cold and dry climate between 25,000 and 12,500 yr BP, interpreted from the grassland vegetation, forest taxa were present in refuges and the shallow local lake began to fill in. Climatic conditions became more aride after 16,000 yr BP, when grassland became rare. From 12,500 yr BP onwards, the climate began to change and at 11,000–9700 yr BP a warm and moist climate permitted the slight migration of pioneer arboreal taxa from refuges and locally a marsh formation. Between 9700 and 6500 yr BP a warm and dry climate resulted in reduction of grassland, confined the forest in refuges, dried out the marsh. The gradual increase of humidity between 6500 and 4000 yr BP allowed migration of forests from refuges and a bog developed. Between 4000 and 2000 yr BP Araucaria forest spread, indicating moister climate. The local bog expanded. From 2000 yr BP onwards, humid but warmer climate seems to result in a lower reproductive capacity of Araucaria forest taxa limiting its expansion. The bog reached the present-day in a decline condition. The results are compared to previous records from Southern Brazil highlands and some places from Argentina in order to better elucidate the climatic and vegetational history of these important South America areas during the late Quaternary. 相似文献
89.
Pierre F.L. Maxted Luisa Morales-Rueda Tom R. Marsh 《Astrophysics and Space Science》2004,291(3-4):307-314
We report the results of an on-going programme to collect lightcurves for EHB binaries with orbital periods P ? 1 d. Degenerate and non-degenerate companions are clearly distinguished by the presence or absence of a reflection effect in these binaries. The amplitude of the reflection effect can be combined with other data to provide an estimate of the mass of the companion star. We find that the fraction of sdB binaries in our sample which have non-degenerate companions is 0.08±0.06 (1?σ error). These non-degenerate companions have very low masses (? 0.1M⊙). This property is not predicted by existing population synthesis models. 相似文献
90.
Rachida Bendaoud M’hamed El Janati Mohamed Elaatmani Luisa Carvalho Zaineb Hajjar Said Ilmen Abdallah Algouti Ahmed Algouti Lahcen Khouchaf 《Arabian Journal of Geosciences》2018,11(17):512
Neoproterozoic volcanic series are exposed in the northern edge of the Saghro massif (Eastern Anti-Atlas, Morocco). Four volcanic rock types (basalt, andesite, dacite, and rhyolite) were distinguished in the Boumalne inlier within the so-called Saghro volcanic sequences based on petrographic and geochemical observations. Boumalne volcanic rocks contain high Al2O3, Fe2O3, Ba, Sr, Zr, Rb, and Nb contents, including calc-alkaline affinity in composition. Boumalne volcanic rocks are similar to other lower-Neoproterozoic volcanic rocks such Agouiniy formation in Sirwa inlier and in other parts of Bou-Azzer inlier. Indeed, they indicate an active subduction signature. The geochemical data show a LREE enrichment compared to HREE. The fractional crystallization has played a major role during the evolution of the magma. The less-siliceous dacitic rocks could have been formed after a low degree of partial melting of mafic parental magma source, whereas the rich-siliceous rhyolite may have been derived from dacitic magma source by a higher degree of fractional crystallization. 相似文献