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排序方式: 共有162条查询结果,搜索用时 558 毫秒
91.
Impact of human activities on the central Mediterranean offshore: Evidence from Hg distribution in box-core sediments from the Ionian Sea 总被引:1,自引:0,他引:1
Rossella Di Leonardo Adriana Bellanca Massimo Angelone Marcella Leonardi Rodolfo Neri 《Applied Geochemistry》2008,23(12):3756-3766
Total Hg concentrations have been measured for five box-core sediments collected seawards of the Augusta industrial area (SE Sicily). In more coastal sediments, upcore increasing Hg concentrations, exceeding the Hg background concentration estimated for the Strait of Sicily, indicate Hg contamination over time due to the industrial area development. Strong correlation between total organic C (TOC) and Hg concentrations was found only for core BX2, that displays organic C to total N (C/N) ratios indicative of autochthonous organic matter. For other sediments, high Hg enrichment factors with respect to TOC indicate, in addition to Hg trapping by TOC, other factors as responsible for Hg accumulation. In the presence of some contribution of detrital organic matter, Hg is mainly adsorbed onto the mineral component of the bottom sediments probably because TOC is saturated by Hg excess. Contaminant impact affected also the open sea environment. Main drivers of Hg flux towards the offshore were dredged materials, which repeatedly discharged sediment, resulting in substantial increases in TOC contents and high C/N ratios. Consistent with the geochemistry of recent turbidites, these anomalous sedimentary inputs induced sediment redox environment modifications, constrained by Mn peaks, which affected Hg distribution. 相似文献
92.
93.
Tassia R.G. Passos Adriana G. Artur Gabriel N. Nóbrega Xosé L. Otero Tiago O. Ferreira 《Geo-Marine Letters》2016,36(3):223-233
The performance of the Walkley–Black wet oxidation chemical method for soil organic carbon (SOC) determination in coastal wetland soils (mangroves, coastal lagoons, and hypersaline tidal flats) was evaluated in the state of Ceará along the semiarid coast of Brazil, assessing pyrite oxidation and its effects on soil C stock (SCS) quantification. SOC determined by the chemical oxidation method (CWB) was compared to that assessed by means of a standard elemental analyzer (CEA) for surficial samples (<30 cm depth) from the three wetland settings. The pyrite fraction was quantified in various steps of the chemical oxidation method, evaluating the effects of pyrite oxidation. Regardless of the method used, and consistent with site-specific physicochemical conditions, higher pyrite and SOC contents were recorded in the mangroves, whereas lower values were found in the other settings. CWB values were higher than CEA values. Significant differences in SCS calculations based on CWB and CEA were recorded for the coastal lagoons and hypersaline tidal flats. Nevertheless, the CWB and CEA values were strongly correlated, indicating that the wet oxidation chemical method can be used in such settings. In contrast, the absence of correlation for the mangroves provides evidence of the inadequacy of this method for these soils. Air drying and oxidation decrease the pyrite content, with larger effects rooted in oxidation. Thus, the wet oxidation chemical method is not recommended for mangrove soils, but seems appropriate for SOC/SCS quantification in hypersaline tidal flat and coastal lagoon soils characterized by lower pyrite contents. 相似文献
94.
Adriana Troyo Douglas O. Fuller Olger Calderón-Arguedas Mayra E. Solano John C. Beier 《Singapore journal of tropical geography》2009,30(2):265-282
Dengue is currently the most important arboviral disease globally and is usually associated with built environments in tropical areas. Remotely sensed information can facilitate the study of urban mosquito-borne diseases by providing multiple temporal and spatial resolutions appropriate to investigate urban structure and ecological characteristics associated with infectious disease. In this study, coarse, medium and fine resolution satellite imagery (Moderate Resolution Imaging Spectrometer, Advanced Spaceborne Thermal Emission and Reflection Radiometer and QuickBird respectively) and ground-based data were analyzed for the Greater Puntarenas area, Costa Rica for the years 2002–04. The results showed that the mean normalized difference vegetation index (NDVI) was generally higher in the localities with lower incidence of dengue fever during 2002, although the correlation was statistically significant only in the dry season (r =−0.40; p = 0.03). Dengue incidence was inversely correlated to built area and directly correlated with tree cover (r = 0.75, p = 0.01). Overall, the significant correlations between dengue incidence and urban structural variables (tree cover and building density) suggest that properties of urban structure may be associated with dengue incidence in tropical urban settings. 相似文献
95.
Kevin O Pope Adriana C Ocampo Alfred G Fischer Walter Alvarez Bruce W Fouke Clyde L Webster Francisco J Vega Jan Smit A.Eugene Fritsche Philippe Claeys 《Earth and Planetary Science Letters》1999,170(4):275-364
Impact ejecta from the Albion Formation are exposed in northern Belize. The ejecta come from the outer portion of the continuous ejecta blanket of the Chicxulub crater, which is located 360 km to the northwest. The basal unit of the Albion Formation is a 1-m-thick clay and dolomite spheroid bed composed of up to four discrete flows. The clay spheroids are altered impact glass, and the dolomite spheroids are accretionary lapilli. The upper unit is a 15-m-thick coarse diamictite bed containing altered glass, large accretionary blocks, striated, polished, and impacted cobbles, and rare shocked quartz. The abundance of accretionary clasts, evidence for atmospheric drag sorting, and the presence of multiple flows in the Albion Formation indicate that atmospheres play an important role in the formation of the outer portions of continuous ejecta blankets of large craters. 相似文献
96.
Palma Massimiliano Iacono Roberto Sannino Gianmaria Bargagli Andrea Carillo Adriana Fekete Balazs M. Lombardi Emanuele Napolitano Ernesto Pisacane Giovanna Struglia Maria Vittoria 《Ocean Dynamics》2020,70(7):935-963
Ocean Dynamics - The tides in the Mediterranean Sea are generally weaker than in other regions of the world ocean, but are locally intensified in passages with complex bathymetry, such as the... 相似文献
97.
Evaluation of a spatial rainfall generator for generating high resolution precipitation projections over orographically complex terrain 总被引:1,自引:1,他引:0
Corrado?CameraEmail author Adriana?Bruggeman Panos?Hadjinicolaou Silas?Michaelides Manfred?A.?Lange 《Stochastic Environmental Research and Risk Assessment (SERRA)》2017,31(3):757-773
Space–time variability of precipitation plays a key role as driver of many environmental processes. The objective of this study is to evaluate a spatiotemporal (STG) Neyman–Scott Rectangular Pulses (NSRP) generator over orographically complex terrain for statistical downscaling of climate models. Data from 145 rain gauges over a 5760-km2 area of Cyprus for 1980–2010 were used for this study. The STG was evaluated for its capacity to reproduce basic rainfall statistical properties, spatial intermittency, and extremes. The results were compared with a multi-single site NRSP generator (MSG). The STG performed well in terms of average annual rainfall (+1.5 % in comparison with the 1980–2010 observations), but does not capture spatial intermittency over the study area and extremes well. Daily events above 50 mm were underestimated by 61 %. The MSG produced a similar error (+1.1 %) in terms of average annual rainfall, while the daily extremes (>50-mm) were underestimated by 11 %. A gridding scheme based on scaling coefficients was used to interpolate the MSG data. Projections of three Regional Climate Models, downscaled by MSG, indicate a 1.5–12 % decrease in the mean annual rainfall over Cyprus for 2020–2050. Furthermore, the number of extremes (>50-mm) for the 145 stations is projected to change between ?24 and +2 % for the three models. The MSG modelling approach maintained the daily rainfall statistics at all grid cells, but cannot create spatially consistent daily precipitation maps, limiting its application to spatially disconnected applications. Further research is needed for the development of spatial non-stationary NRSP models. 相似文献
98.
The efficiency of the biological removal of carbon and nitrogen from leachates is determined by the activity of microbial populations present in biological reactors. In this work, a complete characterization of bacterial communities revealed by personal genome machine sequencing (PGM) has been carried out from different points of a nitrification–denitrification process operated in an urban landfill. The leachate fed to the treatment is a mixture of young leachate, old leachate, and effluent from an anaerobic digestion process, in a volume ratio of 1:0.9:0.12, respectively. The anoxic and oxic reactors are followed by an ultrafiltration step. Samples are taken from different points of the process. Results reveal the microbial diversity of the samples, which include detection of minority populations that are difficult to explore by other methods. Bacteria belonging to Bacteroidetes and Proteobacteria are dominant in all the samples analyzed. Proteobacteria represents more than 50% of the total population in all cases. Samples taken after the biological treatment show a significant reduction in the relative abundance of Firmicutes, Tenericutes, and Lentisphaerae phyla in comparation with the initial leachate. The relative abundance of the classes is also studied and the most abundant in the samples are β‐Proteobacteria and Flavobacteria. 相似文献
99.
Adriana Zingone Laurent Dubroca Daniele Iudicone Francesca Margiotta Federico Corato Maurizio Ribera d’Alcalà Vincenzo Saggiomo Diana Sarno 《Estuaries and Coasts》2010,33(2):342-361
The climatology and interannual variability of winter phytoplankton was analyzed at the Long Term Ecological Research Station
MareChiara (LTER-MC, Gulf of Naples, Mediterranean Sea) using data collected from 1985 to 2006. Background winter chlorophyll
values (0.2–0.5 μg chl a dm−3) were associated with the dominance of flagellates, dinoflagellates, and coccolithophores. Winter biomass increases (<5.47 μg
chl a dm−3) were often recorded until 2000, generally in association with low-salinity surface waters (37.3–37.9). These blooms were
most often caused by colonial diatoms such as Chaetoceros spp., Thalassiosira spp., and Leptocylindrus danicus. In recent years, we observed more modest and sporadic winter biomass increases, mainly caused by small flagellates and small
non-colonial diatoms. The resulting negative chl a trend over the time series was associated with positive surface salinity and negative nutrient trends. Physical and meteorological
conditions apparently exert a strict control on winter blooms, hence significant changes in winter productivity can be foreseen
under different climatic scenarios. 相似文献
100.
Vincenzo Artale Sandro Calmanti Adriana Carillo Alessandro Dell’Aquila Marine Herrmann Giovanna Pisacane Paolo M. Ruti Gianmaria Sannino Maria Vittoria Struglia Filippo Giorgi Xunqiang Bi Jeremy S. Pal Sara Rauscher 《Climate Dynamics》2010,35(5):721-740
We present an atmosphere–ocean regional climate model for the Mediterranean basin, called the PROTHEUS system, composed by the regional climate model RegCM3 as the atmospheric component and by a regional configuration of the MITgcm model as the oceanic component. The model is applied to an area encompassing the Mediterranean Sea and compared to a stand-alone version of its atmospheric component. An assessment of the model performances is done by using available observational datasets. Despite a persistent bias, the PROTHEUS system is able to capture the inter-annual variability of seasonal sea surface temperature (SST) and also the fine scale spatio-temporal evolution of observed SST anomalies, with spatial correlation as high as 0.7 during summer. The close inspection of a 10-day strong wind event during the summer of 2000 proves the capability of the PROTHEUS system to correctly describe the daily evolution of SST under strong air–sea interaction conditions. As a consequence of the model’s skill in reproducing observed SST and wind fields, we expect a reliable estimation of air–sea fluxes. The model skill in reproducing climatological land surface fields is in line with that of state of the art regional climate models. 相似文献