Study of PAH emission from the solid fuels combustion in residential furnaces

The procedure for and results of a test study of polycyclic aromatic hydrocarbon (PAH) emission from a few types of solid fuels combustion in residential furnaces of various designs typical for Belarus are discussed. Greatest levels of PAH emission were detected from domestic wastes and wood waste combustion. Lowest levels of PAH emission are from peat briquette combustion. It was found that PAH concentration in off-gases from firewood combustion also varies significantly depending on the type of wood: the highest values of PAH are typical for waste gases from birch firewood combustion in comparison with pine firewood combustion. Draft PAH emission factors are proposed with intended application for emission inventory of such installations.     

Production and characterization of bioaerosols for model validation in spacecraft environment

This study aimed to evaluate the suitability of two bioaerosol generation systems(dry and wet generation) for the aerosolization of microorganisms isolated from the International Space Station, and to calibrate the produced bioaerosols to fulfill the requirements of computational fluid dynamics model(CFD) validation. Concentration, stability, size distribution, agglomeration of generated bioaerosol and deposition of bioaerosols were analyzed. In addition, the dispersion of non-viable particles in the air was studied.Experiments proved that wet generation from microbial suspensions could be used for the production of well-calibrated and stabile bioaerosols for model validation. For the simulation of the natural release of fungal spores, a dry generation method should be used. This study showed that the used CFD model simulated the spread of non-viable particles fairly well. The mathematical deposition model by Lai and Nazaroff could be used to estimate the deposition velocities of bioaerosols on surfaces, although it somewhat underestimated the measured deposition velocities.     

Recent trends in the decomposition of chlorinated aromatic hydrocarbons by ultrasound irradiation and Fenton's reagent

Over the past few years, a large number of studies have been conducted on the use of ultrasound for decomposition of harmful organic pollutants, particularly chlorinated aromatic hydrocarbons (CAH) in wastewater. The published reports cover a variety of applications, including both ultrasonic treatment alone and in combination with other methods, e.g., advanced chemical oxidation processes. This article presents a review of recent work on ultrasonic-based methods of CAH decomposition, with emphasis on the applications of ultrasound alone and in combination with Fenton's reagent, as attractive advanced oxidation systems. In the first part of this review, the basic principles of sonochemical treatment are presented, followed by a review of the applications of ultrasound alone for CAH degradation. In the second part, the mechanisms of CAH degradation with Fenton's reagent and its application for CAH degradation are summarized. In the final part, studies on the applications of ultrasound together with Fenton's reagent are reviewed. The reported results suggest that a combination of ultrasound and Fenton's reagent is more attractive for practical application than the use of either method separately. Further studies, however, are required in this area because the reaction mechanism and the relationship between the reaction rates and process parameters for such a combined process are not yet well established.     

Fine scale structure of convective mixed layer in ice-covered lake

Environmental Fluid Mechanics - Nonstationary convection forced by distributed buoyancy sources is a fundamental environmental fluid mechanics process, particularly in ice-covered freshwater...     

Rare earth elements upon assessment of reasons of the geophagy in Sikhote-Alin region (Russian Federation), Africa and other world regions

Rocks eaten by wild animals on the Bolshoy Shanduyskiy kudur in the Sikhote-Alin region (Russian Federation) are zeolite–clay mineral complexes—products of weathering of zeolitized vitric tuffs of rhyolite composition, deposited in aqueous medium within the volcanic caldera of about 55 million years ago. By composition of rock-forming oxides, the tuffs refer to high-potassium calc-alkaline series. In trace elements of most favorite kudurites of the Bolshoy Shanduyskiy kudur, there are significantly increased contents of most of rare earth elements (2–5 times in comparison with surrounding rocks). The results of our analysis of geological and geochemical data on kudurs and kudurites in another part of the Sikhote-Alin, as well as on other regions of the world (particularly, in Africa and Indonesia), taking into account new data on the prevalence of rare earth elements in living matter and their medical and biological properties, enable us to consider the version of causal connection of the geophagy with rare earth elements.     

A mesoscale vortex in a small stratified lake

A mesoscale vortex structure in the small stratified Lake Stechlin has been revealed by field experiments with satellite-tracked quasi-lagrangian drifters. The vortex with a radius of about 200 m drifted at 300 m/day along the western bight of the lake with nearly constant rotation speed of 3 cpd. Analysis of kinematical properties of the vortex motion demonstrates solid body character of rotation. Extrapolation of the vortex drift trajectory over the period preceding the observations combined with data on local winds and seiche dynamics has allowed tracing the vortex fate from its generation point. The normal modes analysis of the internal seiching in the lake reveals the vortex generation mechanism to be the interaction of certain seiche modes with local bottom topography and suggests generation of the mesoscale vortices to be the a regular feature of the lake circulation. Analysis of vorticity suggests additional energy supply to rotational flow, possibly from inverse cascading of small-scale turbulent motions—a feature typical for quasi-2D turbulence. The vortices can play an important role in the energy transport from basin-scale motions to small-scale boundary mixing. They can also contribute significantly to the horizontal heterogeneity of phyto- and zooplankton distribution as well as to the transport of dissolved matter such as nutrients between littoral and profundal areas. The topographically generated traveling vortices represent an analog of the synoptic eddies in the Ocean and in the Atmosphere, whereas their role in the lake hydrodynamics is practically unknown.     

Correction to: Documenting lemming population change in the Arctic: Can we detect trends?

Ambio - In the original published article, some of the symbols in figure 1A were modified incorrectly during the typesetting and publication process. The correct version of the figure is provided...     

Marginal Abatement Costs and Marginal Welfare Costs for Greenhouse Gas Emissions Reductions: Results from the EPPA Model

Marginal abatement cost (MAC) curves, relationships between tonnes of emissions abated and the CO₂ (or greenhouse gas (GHG)) price, have been widely used as pedagogic devices to illustrate simple economic concepts such as the benefits of emissions trading. They have also been used to produce reduced-form models to examine situations where solving the more complex model underlying the MAC is difficult. Some important issues arise in such applications: (1) Are MAC relationships independent of what happens in other regions?, (2) are MACs stable through time regardless of what policies have been implemented in the past?, and (3) can one approximate welfare costs from MACs? This paper explores the basic characteristics of MAC and marginal welfare cost (MWC) curves, deriving them using the MIT Emissions Prediction and Policy Analysis model. We find that, depending on the method used to construct them, MACs are affected by policies abroad. They are also dependent on policies in place in the past and depend on whether they are CO₂-only or include all GHGs. Further, we find that MACs are, in general, not closely related to MWCs and therefore should not be used to derive estimates of welfare change. We also show that, as commonly constructed, MACs may be unreliable in replicating results of the parent model when used to simulate GHG policies. This is especially true if the policy simulations differ from the conditions under which the MACs were simulated.     

Changes in Near-Surface Temperature and Sea Level for the Post-SRES CO2-Stabilization Scenarios

Changes in global near-surface temperature and sea level are calculated from 2000 to 2100 for the Post-SRES (Special Report on Emissions Scenarios) scenarios that stabilize the CO₂ concentration early in the 22nd century. Seven stabilization scenarios are examined together with their corresponding SRES marker scenarios – A1, A1/S450, A1/S550, A1/S650, A2, A2/S550, A2/S750, B1, B1/S450, B2, and B2/S550 – where the number following the S indicates the stabilized CO₂ concentration in parts per million by volume (ppmv). The calculations are performed using an energy-balance-climate/upwelling-diffusion-ocean model for three values of the climate sensitivity, ΔT _2x =1.5, 2.5 and 4.5°C. The resulting reductions in global warming and sea-level rise for the stabilization scenarios relative to their corresponding marker scenario increases with ΔT _2x and are greater the lower the stabilized CO₂ concentration. For the S550 stabilization scenarios, the reductions in global warming and sea-level rise in 2100 range from 0.29°C and 3.31 cm for B2/S550 with ΔT _2x =1.5°C, to 1.23°C and 11.81 cm for A2/S550 with ΔT _2x =4.5°C. The percent reductions for the global warming and sea-level rise for each stabilization scenario are almost independent of ΔT _2x and range respectively from about 16% and 12% for the A1/S650 scenario to about 39% and 30% for the A1/S450 scenario. The geographical distributions of near-surface temperature change are constructed using a method to superpose the patterns simulated by our atmospheric general-circulation/mixed-layer-ocean model, individually for doubled CO₂ concentration and decupled SO₄ burden. Results are illustrated for the B2 and B2/S550 scenarios for ΔT _2x =2.5°C. The near-surface temperature changes of the B2/S550 scenario in 2100 are everywhere smaller than those for the B2 scenario, with values ranging from about 0.3°C in the tropics to 0.5°C over Antarctica and 0.7°C in the Arctic. The global results of this study are available on the web at: http://crga.atmos.uiuc.edu/research/post-sres.html. We would be pleased to collaborate with other researchers in using these results in impact and integrated-assessment studies. This revised version was published online in July 2006 with corrections to the Cover Date.     

The feasibility of decontamination of reduced saline sediments from copper using the electrokinetic process

The remediation of metal contamination in estuarine and reduced sediments is another challenge for the electrokinetic process. Problems result from the complex chemical composition of saline reduced sediments. In the experiments described here copper was added into saline reduced sediments to simulate the natural situation. Two constant voltages were applied across the electrokinetic cell to investigate the effect of an increase in potential difference on the electrokinetic process. Acetic acid at pH 6 and 4 was also added to the cathode in separate experiments to enhance copper removal. The results from this study showed that in the unenhanced experiments most of copper remained in the soil and was unaffected by the electrokinetic process. At the end of unenhanced electrokinetic experiments, the copper concentration was found only to be slightly changed in the anode region. Up to 21% of the copper was found precipitated near the anode when the applied voltage was 10V and this increased to 25% when the applied voltage was 7V. In the enhanced electrokinetic experiments up to 98% of copper was removed from section 1 and precipitated again in sections 2 and 3. This indicates that a significant amount copper removal from the saline sediments may be achieved by the enhanced electrokinetic process.