Assessing the effects of transboundary ozone pollution between Ontario,Canada and New York,USA

We investigated the effects of transboundary pollution between Ontario and New York using both observations and modeling results. Analysis of the spatial scales associated with ozone pollution revealed the regional and international character of this pollutant. A back-trajectory-clustering methodology was used to evaluate the potential for transboundary pollution trading and to identify potential pollution source regions for two sites: CN tower in Toronto and the World Trade Center in New York City. Transboundary pollution transport was evident at both locations. The major pollution source areas for the period examined were the Ohio River Valley and Midwest. Finally, we examined the transboundary impact of emission reductions through photochemical models. We found that emissions from both New York and Ontario were transported across the border and that reductions in predicted O3 levels can be substantial when emissions on both sides of the border are reduced.     

Drivers of deforestation and degradation for 28 tropical conservation landscapes

Analysing the drivers of deforestation and forest degradation in conservation landscapes can provide crucial information for conservation management. While rates of forest loss can be measured through remote sensing, on the ground information is needed to confirm the commodities and actors behind deforestation. We administered a questionnaire to Wildlife Conservation Society’s landscape managers to assess the deforestation drivers in 28 tropical conservation landscapes. Commercial and subsistence agriculture were the main drivers of deforestation, followed by settlement expansion and infrastructure development. Rice, rubber, cassava and maize were the crops most frequently cited as drivers of deforestation in these emblematic conservation landscapes. Landscape managers expected deforestation trends to continue at similar or greater magnitude in the future, calling for urgent measures to mitigate these trends.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01325-9) contains supplementary material, which is available to authorized users.     

A comprehensive review of hydrophobic silica and composite aerogels: synthesis,properties and recent progress towards environmental remediation and biomedical applications

Environmental Science and Pollution Research - The hydrophobicity of silica and composite aerogels has enabled them to acquire applications in a variety of fields. With remarkable structural,...     

Allometric models for the estimation of above- and below-ground biomass of Jatropha curcas L. in semi-arid regions of Southern India

Jatropha curcas L. (Jatropha) is an important multipurpose tree valued for oil. In India, plans are underway to bring substantial area under this crop for meeting the biofuel requirements of the country. A study was conducted to develop allometric relationships in Jatropha to predict various biomass-related components (above ground and below ground) using easily measurable attributes, viz. collar diameter, tree height, number of branches, crown diameter, and crown depth. Further, it was aimed to establish the reliability of these relationships using an independent dataset obtained from varied management situations. Destructive sampling was carried out during the rainy season of 2011, when Jatropha plants were eight years old. Highly significant allometric relationships (F-values significant at 1% level) were obtained while predicting various biomass components (above, below, and total) using easily measurable attributes with R² values ranging from 0.89 to 0.98. Of all the predictors, collar diameter exhibited a highly significant relationship with total dry biomass per plant (R² = 0.97). The allometric relationships developed were validated with an independent dataset. The allometric relationships developed would serve as valuable tools for estimating total dry biomass production and carbon sequestration with reasonable accuracy in Jatropha systems, as they are proposed to be taken up in substantial area in the years to come.     

Assessing the impacts of partial mass depletion in DNAPL source zones I. Analytical modeling of source strength functions and plume response

Analytical solutions are developed for approximating the time-dependent contaminant discharge from DNAPL source zones undergoing dissolution and other decay processes. The source functions assume a power relationship between source mass and chemical discharge and can consider partial DNAPL source remediation (depletion) at any time after the initial DNAPL release. The source functions are used as a time-dependent boundary condition in an idealized chemical transport model to develop leading order approximations of the plume response to DNAPL source removal. The results suggest that partial DNAPL remediation does not tend to have a dramatic impact on the maximum extent of the plume if very low concentration values are used to define the plume boundaries. However, the solutions show that partial DNAPL removal from the source zone is likely to lead to large reductions in plume concentrations and mass, and it reduces the longevity of the plume. When the mass discharge from the source zone is linearly related to the DNAPL mass, it is shown that partial DNAPL depletion leads to linearly proportional reductions in the plume mass and concentrations.     

Stabilization and solidification of metal-laden wastes by compaction and magnesium phosphate-based binder

Bench-scale and full-scale investigations of waste stabilization and volume reduction were conducted using spiked soil and ash wastes containing heavy metals such as Cd, Cr, Pb, Ni, and Hg. The waste streams were stabilized and solidified using chemically bonded phosphate ceramic (CBPC) binder, and then compacted by either uniaxial or harmonic press for volume reduction. The physical properties of the final waste forms were determined by measuring volume reduction, density, porosity, and compressive strength. The leachability of heavy metals in the final waste forms was determined by a toxicity characteristic leaching procedure (TCLP) test and a 90-day immersion test (ANS 16.1). The structural composition and nature of waste forms were determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. CBPC binder and compaction can achieve 80-wt% waste loading and 39-47% reduction in waste volume. Compressive strength of final waste forms ranged from 1500 to 2000 psi. TCLP testing of waste forms showed that all heavy metals except Hg passed the TCLP limits using the phosphate-based binder. When Na2S was added to the binder, the waste forms also passed TCLP limits for Hg. Long-term leachability resistance of the final waste forms was achieved for all metals in both soil and ash wastes, and the leachability index was approximately 14. XRD patterns of waste forms indicated vermiculite in the ash waste was chemically incorporated into the CBPC matrix. SEM showed that waste forms are layered when compacted by uniaxial press and are homogeneous when compacted by harmonic press.     

Cosolvent-enhanced chemical oxidation of perchloroethylene by potassium permanganate

A laboratory study was conducted to examine cosolvent-enhanced in-situ chemical oxidation (ISCO) of perchloroethylene (PCE) using potassium permanganate (KMnO4). The conceptual basis for this new technique is to enhance permanganate oxidation of dense non-aqueous phase liquids (DNAPLs) with the addition of a cosolvent, thereby increasing DNAPL solubility while avoiding mobilization. Among 17 cosolvent candidates screened, tertiary butyl alcohol (TBA) and acetone were the most stable in the presence of KMnO4, both of which increased PCE aqueous solubility significantly, and therefore are suitable to be used as cosolvent in this study. Batch experiments indicated that the second-order rate constant for PCE oxidation by potassium permanganate was 0.043+/-0.002 M(-1) s(-1) in the purely aqueous (no cosolvent) solution. In the presence of 20% cosolvent (volume fraction=fc=0.2), the rate constant decreased to 0.036+/-0.003 M(-1) s(-1) with TBA and to 0.031+/-0.002 M(-1) s(-1) with acetone. However, in the presence of free-phase PCE, chloride ion concentration from PCE oxidation in acetone/water solutions (fc=0.2) was about twice that in aqueous solutions, indicating that the increase in PCE solubility more than compensated for the decrease in reaction rate constant, such that the oxidation efficiency of PCE was increased with cosolvent. A complete chlorine mass balance was observed in the aqueous system, whereas approximately 70% was obtained in TBA/water or acetone/water (fc=0.2). In soil columns containing residual DNAPL and subjected to isocratic flushing with step-wise increases in f(c) cosolvent, TBA at fc=0.2 resulted in PCE mobilization, whereas acetone at fc相似文献   

海化集团自备热电厂1#炉除尘系统改造

针对海化集团自备热电厂130 t/h煤粉炉原有除尘系统存在的问题进行了全面的分析,在此基础上,结合厂方提出的要求,确定了改造方案,并进行了改造设计.改造后实际运行情况表明:1#炉除尘系统运行良好,除尘效率超出厂方提出的要求,达到98.5%以上.     

欧盟绿色壁垒对我国出口产品的影响分析

欧盟绿色壁垒虽然从客观上促使我国加强环境保护、推进可持续发展战略,但也严重限制了我国主要出口产品的对欧贸易。“绿色”外衣下掩盖的是贸易保护的实质。我国惟有努力提高环保标准和管理水平,提高企业和产品的环境竞争力,才能有效突破绿色壁垒,力争贸易与环保双赢。     

Microbial ecology of the soils of Indian desert

A comprehensive study on the microbial ecology of Indian desert soils was carried out. Although different groups of microorganisms e.g., fungi, actinomycetes, bacteria, Azotobacter and nitrifying bacteria were present, but in relatively low numbers, there was considerable variation in numbers from one site to another within the desert as the physicochemical characters of the soils varied. Actinomycetes formed a high proportion of the total microflora. In the majority of the soils, 80% of the fungal population belonged to the genera Aspergillus and Penicillium, while Gram-positive spore formers were the dominant group among bacteria. No significant decline in the population of microorganisms was observed during summer, in spite of high surface soil temperatures. Microbiological properties of these soils also varied depending on the type of land use pattern: grasslands, in general, supported higher numbers of microorganisms than three plantations, cultivated fields or barren land. Stabilization of shifting and sand dunes introduction of vegetation has markedly increased the soil microflora. In general the low organic matter content and poor moisture availability of desert soils were the major factors limiting optimum microbial activity.