A Comparison of Data‐Driven Groundwater Vulnerability Assessment Methods     

Alessandro Sorichetta  Cristiano Ballabio  Marco Masetti  Gilpin R. Robinson Jr.  Simone Sterlacchini 《Ground water》2013,51(6):866-879

Increasing availability of geo‐environmental data has promoted the use of statistical methods to assess groundwater vulnerability. Nitrate is a widespread anthropogenic contaminant in groundwater and its occurrence can be used to identify aquifer settings vulnerable to contamination. In this study, multivariate Weights of Evidence (WofE) and Logistic Regression (LR) methods, where the response variable is binary, were used to evaluate the role and importance of a number of explanatory variables associated with nitrate sources and occurrence in groundwater in the Milan District (central part of the Po Plain, Italy). The results of these models have been used to map the spatial variation of groundwater vulnerability to nitrate in the region, and we compare the similarities and differences of their spatial patterns and associated explanatory variables. We modify the standard WofE method used in previous groundwater vulnerability studies to a form analogous to that used in LR; this provides a framework to compare the results of both models and reduces the effect of sampling bias on the results of the standard WofE model. In addition, a nonlinear Generalized Additive Model has been used to extend the LR analysis. Both approaches improved discrimination of the standard WofE and LR models, as measured by the c‐statistic. Groundwater vulnerability probability outputs, based on rank‐order classification of the respective model results, were similar in spatial patterns and identified similar strong explanatory variables associated with nitrate source (population density as a proxy for sewage systems and septic sources) and nitrate occurrence (groundwater depth).  相似文献   

Preface to the special issue ��Triggered and induced seismicity: probabilities and discrimination��     

Simone Cesca  Bernard Dost  Adrien Oth 《Journal of Seismology》2013,17(1):1-4

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Dune fields on Mars: Recorders of a climate change?     

Emilie Gardin  Pascal Allemand  Cathy Quantin  Simone Silvestro  Christophe Delacourt 《Planetary and Space Science》2012,60(1):314-321

Dunes have similar morphologies on the Earth and Mars. The main differences between Martian and terrestrial dunes are their size, which is larger on Mars, and their duration of formation, which is longer on Mars. As the characteristic time of Martian dunes is in the same order as that of the Martian climatic oscillations, Martian dunes could be recorders of past winds regimes and past climates. In order to test this hypothesis, we performed a morphological study of 550 dune fields with high resolution images and we inferred the directions of the dune formative winds from the orientation of the dune slip faces. Our study shows that 310 dune fields record one to four distinct wind directions with some geometric patterns that do not exist on the Earth such as barchans built by opposite wind directions coexisting in the same dune field. Our study demonstrates that the inferred formative wind directions are only partially in agreement with the current wind-patterns predicted by General Circulation Models (GCM). Several possible causes for the misalignment between dunes and GCM outputs are discussed: these include the local variation of the global circulation due to local topographic effects or the possibility that these dunes could be in a transient geometry or fossil. Such bedforms are considered indeed to be not in equilibrium with the present-day atmospheric conditions. This latter hypothesis is supported by the presence, in some ergs, of closely spaced dunes showing nearly opposite slip face orientations. Therefore, we propose that Martian dune fields are constituted, in some cases, by active and fossil dunes and therefore have the potential to preserve information on paleoclimates over extensive periods.  相似文献   

Impact of explosive volcanic eruptions around Vesuvius: a story of resilience in Roman time     

Claudio Scarpati  Annamaria Perrotta  Girolamo Ferdinando De Simone 《Bulletin of Volcanology》2016,78(3):21

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Isolation and characterization of two crude oil-degrading yeast strains, Yarrowia lipolytica PG-20 and PG-32, from the Persian Gulf   总被引：1，自引：0，他引：1  

Hassanshahian M  Tebyanian H  Cappello S 《Marine pollution bulletin》2012,64(7):1386-1391

Among six crude oil-degrading yeasts that were isolated from an oil-polluted area in the Persian Gulf, two yeast strains showed high degradation activity of aliphatic hydrocarbons. From an analysis of 18S rRNA sequences and biochemical characteristics, these strains were identified as Yarrowia lipolytica strains PG-20 and PG-32. Gas Chromatography (GC) analysis of the crude oil remaining in the culture medium after 1 week at 30°C showed that the strains PG-20 and PG-32 degraded 68% and 58% of crude oil, respectively. The optimal growth condition and biodegradation of hydrocarbons was in ONR medium with an acidic pH (pH5). These two strains may degrade aliphatic hydrocarbons more efficiently than aromatic hydrocarbons, although strain PG-20 had better degradation than strain PG-32. The two Y. lipolytica strains reduce surface tension when cultured on hydrocarbon substrates (1% v/v). These strains showed a cell surface hydrophobicity higher than 70%. These results suggested that Y. lipolytica strains PG-20 and PG-32 have high crude oil degrading activity due to their high emulsifying activity and cell hydrophobicity. In conclusion, these yeast strains can be useful for the bioremediation process in the Persian Gulf and decreasing oil pollution in this marine ecosystem.  相似文献   

Lava flow hazard and risk at Mt. Cameroon volcano     

Massimiliano Favalli  Simone Tarquini  Paolo Papale  Alessandro Fornaciai  Enzo Boschi 《Bulletin of Volcanology》2012,74(2):423-439

Mt. Cameroon is one of the most active effusive volcanoes in Africa. About 500,000 people living or working around its fertile flanks are subject to significant threat from lava flow inundation. Lava flow hazard and risk were assessed by simulating probable lava flow paths using the DOWNFLOW code. The vent opening probability density function and lava flow length distribution were determined on the basis of available data from past eruptions at Mt. Cameroon volcano. Code calibration was performed through comparison with real lava flow paths. The topographic basis for simulations was the 90-m resolution SRTM DEM. Simulated lava flows from about 80,000 possible vents were used to produce a detailed lava flow hazard map. The lava flow risk in the area was mapped by combining the hazard map with digitized infrastructures (i.e., human settlements and roads). Results show that the risk of lava flow inundation is greatest in the most inhabited coastal areas comprising the town of Limbe, which constitutes the center of Cameroon’s oil industry and an important commercial port. Buea, the second most important town in the area, has a much lower risk although it is significantly closer to the summit of the volcano. Non-negligible risk characterizes many villages and most roads in the area surrounding the volcano. In addition to the conventional risk mapping described above, we also present (1) two reversed risk maps (one for buildings and one for roads), where each point on the volcano is classified according to the total damage expected as a consequence of vent opening at that point; (2) maps of the lava catchments for the two main towns of Limbe and Buea, illustrating the expected damage upon venting at any point in the catchment basin. The hazard and risk maps provided here represent valuable tools for both medium/long-term land-use planning and real-time volcanic risk management and decision making.  相似文献   

Phytoplankton abundance, biomass and diversity within and between Pantanal wetland habitats     

Simone Jaqueline Cardoso  Fábio RolandSimoni Maria Loverde-Oliveira  Vera Lúcia de Moraes Huszar 《Limnologica》2012,42(3):235-241

During the high water season, the flooding reduces environmental heterogeneity in aquatic ecosystems of the Pantanal wetland. When the water level recedes, lakes and channels are formed as individual systems. Therefore, we expected the spatial heterogeneity during the low water phase resulting in changes on biological communities leading to high phytoplankton abundance, biomass and diversity within and between habitats. To test this hypothesis, we analyzed eight freshwater systems (five oxbow lakes, two channels, and the river) during the low water period. Phytoplankton biomass, abundance, diversity (alpha, beta, gamma) and diversity metrics as richness (species per sample), Shannon diversity (H′) and evenness were measured in all systems along with nutrient concentrations, zooplankton and bacteria abundances. We found 97 species as gamma diversity. The alpha diversity was unexpectedly low in comparison to most other South American floodplain systems (38 species in river, 24 in channels and 29 in lakes). Also, the systems are relatively similar in composition (beta diversity, 28%). Connectivity differences between systems highlighted differences in phytoplankton abundance and biomass (fresh weight) ranging from 1428 ind mL⁻¹ (river) to 3710 ind mL⁻¹ (lakes) and from 0.71 mg L⁻¹ (river) to 2.9 mg L⁻¹ (lakes), respectively. However, our results did not indicate significant differences in phytoplankton species richness between the systems during the low water. Our main conclusions are that local factors may be responsible for changes on phytoplankton community and the time of isolation during the low water phase was not sufficient to promote changes in phytoplankton diversity between the habitats.  相似文献   

A comparison between manganese nodules and cobalt crust economics in a scenario of mutual exclusivity     

Simone Martino  Lindsay M. Parson 《Marine Policy》2012,36(3):790-800

The past 20 years have been characterised by limited interest in the economic viability of deep seabed mining with the exception of those mineral ores rich in precious metals such as polymetallic sulphides. This paper goes against the tide. After reviewing the most significant literature, it compares the economic feasibility of mining polymetallic manganese nodules and cobalt-rich ferromanganese crusts in a scenario of mutual exclusivity. It uses a new indicator, the cobalt-nickel price ratio, whose aim is to verify at what metal prices the net present value of the two mining projects equalises. Previous research has shown that the turning margin between manganese nodules and cobalt crusts is a cobalt price of $50/kg. The present paper revises this by showing that the choice between mining crust and nodules depends on fluctuations in the price of nickel. A Monte Carlo simulation proves that cobalt crust mining could be reasonably preferred to manganese nodules at cobalt prices of $40-60/kg if the price of nickel fell below $11/kg. Within this condition, investors would receive the minimum acceptable internal rate of return of 15%, which is at a level of risk closer to the land-based mining. However, when the price of nickel passes the $11/kg threshold, the equilibrium between the two ventures can be reached only at a cobalt price greater than $100/kg, causing cobalt crust to become uncompetitive. Finally, the paper, recognising that prices are not unique drivers, introduces legal, political, technological and environmental concerns to show that the final choice between the two mining ventures cannot be merely driven by economic issues.  相似文献   

Global dynamical properties of the Fermi–Pasta–Ulam system     

Simone Paleari  Claude Froeschlé  Elena Lega 《Celestial Mechanics and Dynamical Astronomy》2008,102(1-3):241-254

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Sustainable development and anthropogenic induced geomorphic hazards in subsiding areas          下载免费PDF全文

Najib Abou Karaki  Simone Fiaschi  Damien Closson 《地球表面变化过程与地形》2016,41(15):2282-2295

In many areas of the world, subsidence related to the lowering of the water table is modifying the landscape and provoking costly environmental hazards. We consider the Dead Sea (the Earth's lowest lake) as a model. Its water level was 395 m bMSL in the 1960s. Due to water diversions in the catchment area, as of 2016, the level has dropped to about 430 m bMSL. Here, as in other parts of the Anthropocene world, from China, to Iran, to Turkey, to Canada and the United States, consequences of human interventions are rapidly modifying the environment. Aggressive geomorphic processes leading to accelerated degradations are taking place and affecting landforms and infrastructures. In Tectonic terms, the lake is a pull‐apart basin resulting from the motion of the Dead Sea Transform fault. Since the 1960s, a slice of brine of about 35 km³ has been lost. The water table is dropping more rapidly in the lake than in the coastal zone creating an ever‐increasing head difference. Consequently, groundwater moves towards the sea to compensate for the imbalance, provoking the reactivation of the area's paleo‐channels with subsidence, sinkholes, and landslides. Since the 1980s, industrial‐touristic infrastructure has covered newly emerging lands in geomorphic hazards‐prone areas of the coastal zone. Time series analysis of high to very high resolution visible/radar satellite images acquired from the 1970s to present, revealed major landscape evolution. Such dynamic systems prevailing in recent decades permitted the study of human/environment interactions to help minimize their effects. Major deformations of an industrial dike were analysed and quantified. The results underline the necessity in the Anthropocene of careful analysis of relevant data sources acquired before and during subsidence, particularly in karst topography zones and prior to the development of major human activities in economically appealing environments around the world. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献