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991.
With a growing awareness of water pollution problems, in recent years there has been a considerable increased effort in developing and applying numerical models to predict accurately the contaminant distributions, particularly in free surface flows. This numerical study presents a predictive hydrodynamic model in order to explore the dispersion phenomenon of a pollutant injected from time-dependent sources in a turbulent free surface flow. More precisely, we study the impact of pulsation on the dispersion of an injected material. The air/water interface was modeled with the volume of fluid method and sharpness of the free surface was assured by means of Geo-Reconstruct scheme. The numerical results showed that the pulsation played a dominant role at the early stage of the pollutant transport. It was also observed that the pulsation affected the distribution of the injected material especially near the front and that a major swirling action was developed compared to the constant-rate-injection case. 相似文献
992.
Guo Ping Yu Shaocai Wang Liqiang Li Pengfei Li Zhen Mehmood Khalid Chen Xue Liu Weiping Zhu Yannian Yu Xing Alapaty Kiran Lichtfouse Eric Rosenfeld Daniel Seinfeld John H. 《Environmental Chemistry Letters》2019,17(3):1333-1340
Environmental Chemistry Letters - Climate change is predicted to induce more extreme events such as storms, heat waves, drought and floods. Dust storms are frequently occurring in northern China.... 相似文献
993.
Raja Jelassi Chedliya Ghemari Hajer Khemaissia Maryline Raimond Catherine Souty-Grosset Karima Nasri-Ammar 《Chemistry and Ecology》2019,35(4):361-378
This study was conducted to compare metals bioaccumulation in the Talitrid O. mediterranea collected from the banks of Bizerte lagoon. Individuals were exposed to a series of contaminated soil with different concentrations of cadmium, copper, and zinc. Biological and physiological responses were highlighted. Body metals concentrations were measured in the talitrid using flame atomic emission spectrometry. Results showed that after the second week, the mortality increased especially with cadmium exposure, and a mass gain was obtained between weeks for copper and zinc. Furthermore, the concentration factor indicated that O. mediterranea could be considered as a macroconcentrator of copper and zinc. Histopathological analysis showed that the different metals concentrations induced significant changes in the morphology and in the ultrastructural organisation of hepatopancreatic cells. Significant alterations obtained after metals exposure were the increase in the number of the majority cell organelles. Also, heavy metals were present in the form of numerous granules with different size in the cell surface. Furthermore, metals exposure affected the brush border causing the disruption of microvilli filament. Through these results, O. mediterranea could be a good indicator providing measurable responses. It could be an attractive candidate for the biochemical study of heavy metals toxicity in coastal ecosystems. 相似文献
994.
Bontemps Christophe Bougherara Douadia Nauges Céline 《Environmental Modeling and Assessment》2021,26(4):609-630
Environmental Modeling & Assessment - Even if there exists an extensive literature on the modeling of farmers’ behavior under risk, actual measurements of the quantitative impact of risk... 相似文献
995.
《Atmospheric environment (Oxford, England : 1994)》2005,39(19):3565-3572
This work explores the application of fractional Brownian motion (FBM) analysis to SEM micrographs of soot aggregates exhausted by a model dynamometer. By directly quantifying the surface texture of fractal-like aggregates to extract their Hurst coefficients (H), the FBM analysis was successful in parameterizing fractal dimension (Df) values, from which the relative aggregate structure variables could easily be determined. For two microscopic magnification scales (×50,000 and ×105), the soot aggregate Df fell in the range of 1.6–1.7. The experimental results closely agreed with the main conclusions derived from previous studies. An alternative approach is to clarify the impact of image properties on Df measurements due to digital image processing and data recording. A twofold change in SEM magnification size gave rise to a 7% deviation, and scaling up from the original image increased the discrepancy compared to miniaturization. In conclusion, texture characterization is useful for estimating the fractal properties of most chain-like or cluster soot aggregates. 相似文献
996.
《Atmospheric environment (Oxford, England : 1994)》2005,39(14):2661-2672
The possible occurrence of polluted aerosols formed by a bubbling mechanism from hydrocarbon-rich aqueous surface layers was investigated in laboratory through the determination of hydrocarbon adsorption from diluted solutions.Benzene and cyclohexane both exhibited positive adsorption. Further to our previous demonstration of lead nitrate coadsorption with benzene near the solubility limit (Sadiki et al., 2003. Atmospheric Environment 37, 3551–3559) the present study revealed a positive coadsorption of lead nitrate with both hydrocarbons, even in diluted solutions.The use of the bubble-column (Wan, Tokunaga, 1998. Environment Science and Technology 32, 3293–3298) as an experimental tool is discussed as well as the physico-chemical mechanisms involved in adsorption and coadsorption processes with their impact on the environment. 相似文献
997.
《Atmospheric environment (Oxford, England : 1994)》2005,39(16):2945-2955
Within 2 years of trace gas measurements performed at Arosa (Switzerland, 2030 m above sea level), enhanced ozone mixing ratios were observed during south foehn events during summer and spring (5–10 ppb above the median value). The enhancements can be traced back to ozone produced in the strongly industrialized Po basin as confirmed by various analyses. Backward trajectories clearly show advection from this region during foehn. NOy versus O3 correlation and comparison of O3 mixing ratios between Arosa and Mt. Cimone (Italy, 2165 m asl) suggest that ozone is the result of recent photochemical production (+5.6 ppb on average), either directly formed during the transport or via mixing of air processed in the Po basin boundary layer. The absence of a correlation between air parcel residence times over Europe and ozone mixing ratios at Arosa during foehn events is in contrast to a previous analysis, which suggested such correlation without reference to the origin of the air. In the case of south foehn, the continental scale influence of pollutants emission on ozone at Arosa appears to be far less important than the direct influence of the Po basin emissions. In contrast, winter time displays a different situation, with mean ozone reductions of about 4 ppb for air parcels passing the Po basin, probably caused by mixing with ozone-poor air from the Po basin boundary layer. 相似文献
998.
Cajo J. F. ter Braak Petr Šmilauer Stéphane Dray 《Environmental and Ecological Statistics》2018,25(2):171-197
Correspondence analysis with linear external constraints on both the rows and the columns has been mentioned in the ecological literature, but lacks full mathematical treatment and easily available algorithms and software. This paper fills this gap by defining the method as maximizing the fourth-corner correlation between linear combinations, by providing novel algorithms, which demonstrate relationships with related methods, and by making a detailed study of possible biplots and associated approximations. The method is illustrated using ecological data on the abundances of species in sites and where the species are characterized by traits and sites by environmental variables. The trait data and environment data form the external constraints and the question is which traits and environmental variables are associated, how these associations drive species abundances and how they can be displayed in biplots. With microbiome data becoming widely available, these and related multivariate methods deserve more study as they might be routinely used in the future. 相似文献
999.
Bhawana Jain Ajaya Kumar Singh Hyunook Kim Eric Lichtfouse Virender K. Sharma 《Environmental Chemistry Letters》2018,16(3):947-967
Nowadays, the water ecosystem is being polluted due to the rapid industrialization and massive use of antibiotics, fertilizers, cosmetics, paints, and other chemicals. Chemical oxidation is one of the most applied processes to degrade contaminants in water. However, chemicals are often unable to completely mineralize the pollutants. Enhanced pollutant degradation can be achieved by Fenton reaction and related processes. As a consequence, Fenton reactions have received great attention in the treatment of domestic and industrial wastewater effluents. Currently, homogeneous and heterogeneous Fenton processes are being investigated intensively and optimized for applications, either alone or in a combination of other processes. This review presents fundamental chemistry involved in various kinds of homogeneous Fenton reactions, which include classical Fenton, electro-Fenton, photo-Fenton, electro-Fenton, sono-electro-Fenton, and solar photoelectron-Fenton. In the homogeneous Fenton reaction process, the molar ratio of iron(II) and hydrogen peroxide, and the pH usually determine the effectiveness of removing target pollutants and subsequently their mineralization, monitored by a decrease in levels of total organic carbon or chemical oxygen demand. We present catalysts used in heterogeneous Fenton or Fenton-like reactions, such as H2O2–Fe3+(solid)/nano-zero-valent iron/immobilized iron and electro-Fenton-pyrite. Surface properties of heterogeneous catalysts generally control the efficiency to degrade pollutants. Examples of Fenton reactions are demonstrated to degrade and mineralize a wide range of water pollutants in real industrial wastewaters, such as dyes and phenols. Removal of various antibiotics by homogeneous and heterogeneous Fenton reactions is exemplified. 相似文献
1000.
The Mediterranean basin has undergone widespread land cover change. Urbanization of coastal areas, land abandonment of steeper slopes, and agricultural intensification in alluvial plains are recurrent themes. The objective of this study was to examine how vineyard land cover changes have affected agricultural soil erosion in a 50 year period (1950–2011). The study area covers a 235 km2 catchment located near the Gulf of St Tropez. Aerial photographs were used to map land cover in 1950, 1982, 2003 and 2011, and the RUSLE soil erosion model was run to estimate soil erosion.Between 1950 and 2011, vineyard went from about 2,426 ha to 1,561 ha. Mean soil erosion increased as vineyard slopes became steeper (11.8 T ha?1, 13.2 T ha?1, 14.4 T ha?1 and 13.5 T ha?1 for 1950, 1982, 2003 and 2011). Total erosion decreased after 1982: 28,621 T y?1 in 1950, 29,030 T y?1 in 1982, 22,848 T y?1 in 2003, and 21,074 T y?1 in 2011. Total soil loss in 2011 is about 75% of values in 1950–1982, so impacts on water pollution and channel dredging have evolved positively over time. 相似文献