Dispersion Conditions Research Articles

Modeling Reactive Ammonia Uptake by Secondary Organic Aerosol in a Changing Climate: A WRF-CMAQ Evaluation

In addition to the well-constrained inorganic acid-base chemistry of ammonia resulting in fine particulate matter (PM2.5) formation, ammonia also reacts with certain organic compounds in secondary organic aerosol (SOA) to produce less basic nitrogen-containing organic compounds. In this study, the potential meteorology and air quality impacts of the heterogeneous uptake of NH3 by SOA are investigated using the WRF-CMAQ two-way coupled model, which calculates the two-way radiative forcing feedback caused by aerosol between meteorology and chemistry in a single simulation. Simulations with and without the NH3-SOA uptake are performed over the contiguous US for July 2014 and July 2050 under the RCP 8.5 IPCC scenario to study the potential impact of climate change. A comparison with multiple observation network data shows that the NH3-SOA uptake improves the model performance for PM2.5 prediction (bias reduced from −22% to −17%), especially the underestimation of organic carbon over the Southeastern US (bias reduced from −17% to −7%). Secondly, the addition of the NH3-SOA chemistry significantly impacts the concentration of NH3 and NH4+, thus affecting the modeled particle acidity. Including the NH3-SOA uptake also impacts the meteorological conditions through the WRF-CMAQ two-way feedback. Moreover, the impact on meteorological conditions results in different windspeed or dispersion conditions, thus affecting air quality predictions. Finally, simulations including the NH3-SOA uptake under the warmer climate conditions of 2050 show a smaller impact on air quality predictions than it does under current climate conditions. This study confirms the importance and necessity of including NH3-SOA chemistry in air quality predictions.

Thermoelectric Properties of Cu2Te Nanoparticle Incorporated N-Type Bi2Te2.7Se0.3.

To develop highly efficient thermoelectric materials, the generation of homogeneous heterostructures in a matrix is considered to mitigate the interdependency of the thermoelectric compartments. In this study, Cu2Te nanoparticles were introduced onto Bi2Te2.7Se0.3 n-type materials and their thermoelectric properties were investigated in terms of the amount of Cu2Te nanoparticles. A homogeneous dispersion of Cu2Te nanoparticles was obtained up to 0.4 wt.% Cu2Te, whereas the Cu2Te nanoparticles tended to agglomerate with each other at greater than 0.6 wt.% Cu2Te. The highest power factor was obtained under the optimal dispersion conditions (0.4 wt.% Cu2Te incorporation), which was considered to originate from the potential barrier on the interface between Cu2Te and Bi2Te2.7Se0.3. The Cu2Te incorporation also reduced the lattice thermal conductivity, and the dimensionless figure of merit ZT was increased to 0.75 at 374 K for 0.4 wt.% Cu2Te incorporation compared with that of 0.65 at 425 K for pristine Bi2Te2.7Se0.3. This approach could also be an effective means of controlling the temperature dependence of ZT, which could be modulated against target applications.

Comparative Study of Source Inversion Under Multiple Atmospheric Pollutant Emission Scenarios

Source inversion is an effective approach for estimating air pollutant source parameters (e.g., source emission or source strength [Q0], source horizontal location [x0, y0], and release height [z0]) in industrial activities or accidents. Air pollution events in the real world generally correspond to complex application scenarios arising from unknown source parameters (i.e., Q0, [Q0, z0], [Q0, x0, y0], and [Q0, x0, y0, z0]) and atmospheric dispersion conditions. However, the source inversion characteristic law of these complex practical scenarios and the interaction mechanism between source location prior information and source strength inversion have not been revealed. In this study, the source inversion performance (accuracy and robustness) under the aforementioned scenarios was evaluated based on the Prairie Grass field experiments. Results indicated that the estimation accuracy of source strength was worse with an increase in the number of unknown source parameters with absolute relative deviations of 34.4, 46.0, 80.1, and 83.6% for a single parameter and double, triple, and quadruple parameters, respectively. Source strength inversion performance was obviously affected by location parameters; robustness was markedly reduced when source height was unknown, whereas accuracy was obviously reduced when source horizontal locations were unknown. Impacts of atmospheric conditions on different source parameters were distinct. Extreme atmospheric conditions (stability A and F) can obviously reduce the estimation accuracy of source strength for single and double parameter inversion scenarios, whereas unstable conditions (stability A, B, and C) can reduce the estimation accuracy of source strength for triple and quadruple parameter scenarios. Source inversion accuracy and robustness were generally poor under extremely stable conditions. This study can fill the knowledge gap in characteristic laws of source inversion under complex application scenarios and the interaction relationship between different unknown source parameters. The results of the influence law of location prior information on source strength inversion have important guiding significance to further improve the inversion accuracy of source strength in practical environmental managements.

Spatiotemporal characteristics, influencing factors and evolution laws of water exchange capacity of Poyang Lake

As an important indicator of pollutant transport and dispersion conditions in lakes, the water exchange capacity of large shallow lakes has always been a focus in research on lake hydrodynamic and water environment. Poyang Lake is a large shallow lake and also the largest freshwater lake in China, which is being given prominent environmental and ecological status. Poyang Lake’s hydrological situation fluctuates dramatically and the spatial and temporal characteristics and influencing factors of its water exchange capacity are complicated. In this paper, water age was selected to describe the water exchange capacity of Poyang Lake, and a water age model of Poyang Lake was established. With the water age model, the spatial and temporal characteristics and influencing factors of water age of Poyang Lake were studied and the law of response of the water age to the evolution of River-Lake relationship between Yangtze River and Poyang Lake and the proposed Poyang Lake Water Conservancy Hub was analyzed. The results showed that: (1) The water age of Poyang Lake demonstrates significant spatial and temporal heterogeneity, that is, the water age in summer and autumn is obviously higher than that in winter and spring and the water age in the disc-shaped lake and lake bay area is obviously higher than that in the main river channel and beach; (2) The water stage at Hukou and catchment inflow are the main factors affecting the water age of Poyang Lake and the influence of the water stage at Hukou on the water age of Poyang Lake is greater than that of the catchment inflow, and the higher water stage at Hukou, the higher the water age of Poyang Lake, while the higher the catchment inflow, the lower the water age of Poyang Lake; (3) After 2003, the water age of Poyang Lake decreases with the evolution of River-Lake relationship and the most significant decrease happens in autumn; (4) The proposed Poyang Lake Water Conservancy Hub may increase the water age of Poyang Lake to some extent while it alleviates the problem of low water in Poyang Lake. This study can provide a scientific base for the water environment management of Poyang Lake and provide a reference for research on water exchange capacity of other large shallow lakes.

Assessment of the link between atmospheric dispersion and chemical composition of PM10 at 2-h time resolution

The concentration of air pollutants is governed by both emission rate and atmospheric dispersion conditions. The role played by the atmospheric mixing height in determining the daily time pattern of PM components at the time resolution of 2 h was studied during 21 days of observation selected from a 2-month field campaign carried out in the urban area of Rome, Italy.Natural radioactivity was used to obtain information about the mixing properties of the lower atmosphere throughout the day and allowed the identification of advection and stability periods. PM10 composition was determined by X-ray fluorescence, ion chromatography, inductively coupled plasma-mass spectrometry and thermo-optical analysis. A satisfactory mass closure was obtained on a 2-h basis, and the time pattern of the PM10 macro-sources (soil, sea, secondary inorganics, organics, traffic exhaust) was acquired at the same time scale.After a complete quality control procedure, 27 main components and source tracers were selected for further elaboration. On this database, we identified some groups of co-varying species related to the main sources of PM. Each group showed a peculiar behaviour in relation to the mixing depth. PM components released by soil, biomass burning and traffic exhaust, and, particularly, ammonium nitrate, showed a clear dependence on the mixing properties of the lower atmosphere. Biomass burning components and organics peaked during the night hours (around midnight), following the atmospheric stabilization and increased emission rate. Traffic exhausts and non-exhausts species also peaked in the evening, but they showed a second, minor increase between 6:00 and 10:00 when the strengthening of the emission rate (morning rush hour) was counterbalanced by the dilution of the atmosphere (increasing mixing depth). In the case of ammonium nitrate, high concentrations were kept during the whole night and morning.

Advanced light-tolerant microalgae-nitrifying bacteria consortia for stable ammonia removal under strong light irradiation using light-shielding hydrogel

The consortium of microalgae and nitrifying bacteria has attracted attention owing to its advantages, such as energy- and cost-efficiency in terms of using only light irradiation without aeration. However, high light intensity can easily cause photoinhibition of nitrifying bacteria, resulting in process breakdown of the consortium. This challenge limits its practical application in outdoor environment. In a previous study, we developed a “light-shielding hydrogel” which entrapped nitrifying bacteria in carbon black-added alginate hydrogel beads and confirmed its effectiveness of protecting the nitrifying bacteria from intense light up to 1600 μmol photons m−2 s−1. However, the applicability of the light-shielding hydrogel to microalgae–nitrifying bacteria consortia under strong light irradiation has not yet been clarified. In this study, we aimed to establish consortia of Chlorella sorokiniana and nitrifying bacteria immobilised in light-shielding hydrogel and evaluate their nitrification performance under strong light. Three nitrifying bacteria conditions were used: light-shielding hydrogel, hydrogel containing only nitrifying bacteria without carbon black (‘hydrogel’), and dispersed nitrifier without immobilisation (‘dispersion’) as a control. At 1600 μmol photons m−2 s−1, the dispersion afforded a significant decrease in nitrification activity and subsequent process breakdown. In contrast, light-shielding hydrogel achieved complete nitrification without nitrite accumulation and had nitrification rates of approximately nine and two times higher than those for the dispersion and hydrogel conditions, respectively. Based on the overall evaluation, a possible sequence of process breakdown under strong light was also proposed. This study demonstrated for the first time that the light-shielding hydrogel/consortia combination had potential for applications, which require mitigation of photoinhibition under strong light irradiation. Further, it is expected that the proposed method will contribute to realise the practical application of microalgae–nitrifying bacteria consortia in various countries that experience high sunlight intensity due to their location in the sunbelt areas.

МОДЕЛИРОВАНИЕ ЗАГРЯЗНЕНИЯ ПРИЗЕМНОГО ВОЗДУХА С ХАРАКТЕРНЫМИ В ПЕРИОД COVID-19 СОКРАЩЕНИЯМИ ЭМИССИЙ В АТМОСФЕРУ С ИСПОЛЬЗОВАНИЕМ МОДЕЛЕЙ CHIMERE И COSMO-ART

The results of numerical modeling of air pollution using CHIMERE and COSMO-ART chemical transport models are presented. The modeling was performed according to the scenarios of the 50-60% reduction of emissions from anthropogenic sources in the Moscow region during the period of March-July 2020. Scenario calculations of pollutant concentrations were compared with baseline simulations using regionally adapted inventory of anthropogenic pollutant emissions to the atmosphere. The most significant decrease in the concentrations of NO2 and CO was reproduced by the models when emissions from two sectoral sources (vehicles and nonindustrial plants) were reduced. The PM10 drop was mostly influenced by the reduction of emissions from industrial combustion. With the total reduction of emissions from anthropogenic sources as compared to the baseline calculations, the pollutant concentration decreased by 44-54% for NO2, by 38-44% for CO, and by 26-39% for PM10. This generally coincides with the quantitative estimates of the pollution level drop obtained by other authors. The greatest effect of reducing pollutant emissions into the atmosphere was found during the episodes of adverse weather conditions for air purification, when the simulated and observed pollution level increases by 3-5 times as compared to the conditions of intense pollutant dispersion.

Modeling Surface Air Pollution with Reduced Emissions during the COVID-19 Pandemic Using CHIMERE and COSMO-ART Chemical Transport Models

The results of numerical modeling of air pollution using CHIMERE and COSMO-ART chemical transport models are presented. The modeling was performed according to the scenarios of the 50–60% reduction of emissions from anthropogenic sources in the Moscow region during the period of March–July 2020. Scenario calculations of pollutant concentrations were compared with baseline simulations using regionally adapted inventory of anthropogenic pollutant emissions to the atmosphere. The most significant decrease in the concentrations of NO2 and CO was reproduced by the models when emissions from two sectoral sources (vehicles and nonindustrial plants) were reduced. The PM10 drop was mostly influenced by the reduction of emissions from industrial combustion. With the total reduction of emissions from anthropogenic sources as compared to the baseline calculations, the pollutant concentration decreased by 44–54% for NO2, by 38–44% for CO, and by 26–39% for PM10. This generally coincides with the quantitative estimates of the pollution level drop obtained by other authors. The greatest effect of reducing pollutant emissions into the atmosphere was found during the episodes of adverse weather conditions for air purification, when the simulated and observed pollution level increases by 3–5 times as compared to the conditions of intense pollutant dispersion.

Synergy of multiple drivers leading to severe winter haze pollution in a megacity in Northeast China

Severe haze repeatedly shrouded Harbin during the winter of 2019–2020, making it one of the 10 most polluted cities in China for January of 2020. Here we explored the major drivers for the extreme atmospheric pollution events. Enhanced formation of secondary organic and inorganic aerosols was evident at higher pollution levels, accompanied with a sharp growth of aerosol water content (AWC) and a persistent increase of aerosol pH. Non-biomass burning (non-BB) combustion sources were inferred to be relatively stable during the measurement period. The elemental carbon mass apportioned to the non-BB sources exhibited an apparent increasing trend as aerosol concentrations became higher, pointing to the influence of unfavorable dispersion conditions. In addition, biomass burning (BB) emissions were found to be strengthened at higher aerosol concentrations. This trend was associated with a large drop of temperature, presumably indicating that the strengthened BB emissions were due to more intensive use of biomass for heating. In brief, the winter haze events in Harbin were caused by a synergy of three factors, i.e., enhanced secondary aerosol formation, unfavorable dispersion conditions and strengthened BB emissions. A semi-quantitative approach was developed to further estimate the relative importance of these drivers. Strengthened BB emissions were always less responsible for haze events compared to other factors, whereas the less severe and heavily polluted haze events were caused mainly by unfavorable dispersion conditions and enhanced secondary aerosol formation, respectively. This study provides observational evidences for efficient production of secondary species in aerosol water despite the frigid winter in Harbin, and thus highlights the need for effective control of gaseous precursors, both organic and inorganic.

Simulating the pollutant dispersion during persistent Wintertime thermal Inversions over urban areas. The case of Madrid

A correct simulation of the dispersion during wintertime thermal inversions is important not only to improve the physical understanding of the phenomena but also to design and evaluate strategies to improve air quality. In this study WRF with the multilayer urban canopy scheme BEP-BEM is used to simulate the dispersion during one of those episodes over Madrid, Spain, using a passive tracer representing NOx. The results are compared against NOx measurements obtained at 24 ground stations, grouped in 5 zones. The results show a strong spatial variability of dispersive conditions, with a tendency of the pollutants to accumulate in the topographical depressions. Furthermore, a simple methodology is proposed to derive NO2 from NOx concentrations based on an empirical fitting of two months of observations. The statistical indicators for NO2 computed in this way are similar to those obtained with photochemical models, making this approach a valid, and computationally efficient, alternative, in particular for forecasting purposes. In the last part of this contribution, the model is used to derive information that can be useful for air pollution abatement strategies. In particular, it has been found that: 1) there is no pollutant accumulation from one day to the following one, so the air quality of one day is entirely determined by the emissions and meteorological conditions of that day, 2) displacing part of the emissions of the rush hours to the central hours of the day, when the dispersive conditions are more favorable, can significantly reduce the peaks, and to a lesser extent the daily mean, without changing the total amount of pollutants emitted. So, reducing the total amount of pollutants emitted is not the only way to improve air quality. Benefits can be achieved also by redistributing the emissions in a more optimal way during the whole diurnal cycle.

Influence of dispersion conditions and nature of the emulsifier on the dispersity and stability of artificial polymer suspensions based on polyetherimide

Influence of dispersion conditions and nature of the emulsifier on the dispersity and stability of artificial polymer suspensions based on polyetherimide

A finite-element algorithm with a perfectly matched layer boundary condition for seismic modelling in a diffusive-viscous medium

AbstractSeismic numerical modelling involved in each stage of seismic exploration process is aimed at predicting seismograms in an assumed subsurface medium. The energies and phases of waves vary with the presence of fluids, while the frequency-dependent seismic reflections in a reservoir with hydrocarbons was explained using the diffusive-viscous wave (DVW) equation. We proposed a Galerkin finite-element method (FEM) to numerically study the propagation properties of the DVW in fluid-filled media to ascertain the influences of saturated fluids on characteristics of the wavefield. We also theoretically analysed the numerical dispersion and stability condition of the FEM algorithm, which indicated that a minimum of six nodes per wavelength is recommended to achieve more accurate results. In numerical simulation, we presented a non-split perfectly matched layer (NPML) boundary condition for the DVW equation to absorb the artificial reflections in finite-element modelling, using a homogeneous model to demonstrate the effectiveness of the NPML boundary condition through comparisons with the results without the PML condition. Moreover, we modelled the DVW propagation in a fluid-saturated (gas, oil and water) medium with sharp edges and curved interfaces using the proposed method and compared the results with those pertaining to acoustic waves. The numerical results indicated significant amplitude damping and phase variation in the DVW when it propagates across the fluid-saturated layers compared with those of acoustic waves. Furthermore, we compared the numerical results in the fluid-saturated model calculated via the FEM with those calculated via FCT-FDM (flux corrected transport-finite-difference method) to demonstrate the validity of the former.

A Method to Detect Abnormal Gas Dispersion Conditions in Flotation Machines

This short communication presents a methodology to detect abnormal gas dispersion conditions in flotation machines. These abnormal conditions are characterized by the significant presence of cap-shaped bubbles. The approach considers the use of a bubble size analyzer to measure gas dispersion at industrial scale. The detection of abnormal conditions is critical when estimating bubble size by automated software. Otherwise, the estimates are significantly biased, since irregular bubbles are typically removed from the analysis. From the recorded images and the respective black and white representation, the variability of the shadow percentage caused by the bubbles in the vision field, abruptly increases in the presence of cap-shaped bubbles. Experimental conditions with coefficients of variation lower than 60–70% in the shadow percentage represent spherical and spherical-ellipsoidal regimes. In the former, automated bubble sizing software has proved to be sufficiently effective in obtaining reliable results. In the latter, different segmentation techniques have been proposed to obtain satisfactory results. Abnormal conditions are detected under coefficients of variation greater than 80% in the shadow percentage. The presence of cap-shaped bubbles causes inefficiencies in the collection of hydrophobic minerals in the pulp zone as well as disturbances in the separation stage (froth zone). Therefore, the detection of these irregular bubbles is suitable to provide feedback to flotation processes, allowing gas dispersion to be driven towards normal operating conditions.

Using Resonance-Enhanced Multiphoton Ionization Time-of-Flight Mass Spectrometry to Evaluate the Movement of a Constituent in a Multiple Emulsion.

Herein, we propose a method for evaluating the movement of a constituent in a multiple emulsion while maintaining its original dispersed condition. In this study, an oil-in-water-in-oil (O1/W/O2) emulsion was prepared using a two-step emulsification method with styrene as an analyte species in the inner phase (O1). The emulsion was measured using resonance-enhanced multiphoton ionization time-of-flight mass spectrometry without pretreatment such as centrifugation. From a series of obtained mass spectra, a time profile for the peak areas arising from styrene was constructed. When the emulsion was measured immediately following preparation, a time profile composed of a base, positive, and negative signals confirmed the presence of styrene in the O2, O1, and W phases, respectively. Moreover, while a small amount of styrene was present in the inner O1 phase, almost all of the styrene was found in the outer O2 phase. Furthermore, the results of the obtained time profile were converted into a box plot, and a method for the selection of the base, positive, and negative signals was tentatively determined. Then, the movement of styrene among the phases could be evaluated using the time courses of these signals; the time constant of the movement of styrene from an O1/W droplet to the O2 phase was calculated to be 0.8 h.

A study of morphology, UV measurements and zeta potential of Zinc Ferrite and Al2O3 nanofluids

Nanofluids are generally used as working fluids in heat exchangers and heat transfer equipments because of their unique and improved heat efficacy. But their poor stability due to sedimentation and agglomeration with passage of time has limited them to use in practical applications. Stability of the nanofluids can be increased by addition of surfactants, which induces repulsion between the nanoparticles. Present work focuses on morphology, UV measurements and zeta potential measurements of zinc ferrite and aluminium oxide/water nanofluids. Nanofluids were synthesized by homogeneous mixing of zinc ferrite and aluminium oxide nanoparticles in distilled water to obtain different weight concentrations of the nanofluids using Cetyl Trimethyl Ammonium Bromide as surfactant. Results showed that both the nanofluids offer best dispersion conditions as per zeta potential values, allowing quitehigh stability of the nanofluids. Highest values of absorbance i.e. 3.922 and 3.569 were obtained using 0.5 wt% of the Zinc ferrite and Aluminium Oxide/water nanofluids. Also, highest values of zeta potential i.e. 42.7 and 45.2 mV were obtained using 0.02 wt% of the Zinc ferrite and Aluminium Oxide/water nanofluids.

Ultrasensitive multiwall carbon nanotube-mesoporous MCM-41 hybrid-based platform for the electrochemical detection of ascorbic acid.

This work presents for the first time the systematic preparation of a novel carbon nanotube-MCM-41 hybrid employing the mesoporous material MCM-41 as a successful dispersant for multiwall carbon nanotubes (MWCNTs). Relevant dispersion variables such as the amount of MWCNTs, MCM-41 concentration, and sonication time were optimized through a central composite design (CDD)/response surface methodology (RSM). Several solvents were evaluated and N,N-dimethylformamide (DMF) was selected because it allowed reaching stable dispersions with very good electrochemical response. The electrochemical performance of glassy carbon electrodes (GCE) modified with different hybrids was evaluated by cyclic voltammetry (CV) using ascorbic acid (AA) as redox marker, while their surface morphology was characterized by SEM microscopy. The optimal MWCNT-MCM-41 dispersion condition was 0.75 mg mL-1 MWCNTs, 0.25 mg mL-1 MCM-41, and 30 min sonication. Both, electrochemical results and SEM images correlate with a percolation behavior from MWCNT-MCM-41 hybrid. Electrooxidation of AA at GCE modified with the optimal hybrid occurred under diffusion control and exhibited an enhanced current response (65 μA) and a lower overvoltage (-0.005 V) compared to bare GCE (ip = 22 μA, Ep = 0.255 V). The amperometric response of AA at GCE/MWCNT-MCM-41 exhibited remarkable figures of merit, including an ultralow detection limit (1.5 nM), high sensitivity (45.4 × 103 μA M-1), excellent short- and long-term stability, and very good anti-interference ability for AA detection. The analytical applicability of the developed electrochemical sensor was evaluated by sensing AA in several real samples, showing excellent correlation with the values reported by manufacturers in both pharmaceutical and food samples.

Comparing smoke emissions and impacts under alternative forest management regimes

Smoke from wildfires has become a growing public health issue around the world but especially in western North America and California. At the same time, managers and scientists recommend thinning and intentional use of wildland fires to restore forest health and reduce smoke from poorly controlled wildfires. Because of the changing climate and management paradigms, the evaluation of smoke impacts needs to shift evaluations from the scale of individual fire events to long-term fire regimes and regional impacts under different management strategies. To confront this challenge, we integrated three widely used modeling tools to analyze smoke impacts across different management scenarios within a future of changing climate. We applied this multi-stage framework to a case study analysis in the Lake Tahoe basin, in which managers proposed scenarios that involved varying levels of hand- and mechanical-thinning treatments and prescribed fires. We began by using the LANDIS-II model to project daily emissions of fine particulate matter from wildland fires under various climate and management scenarios over a century. We also modeled dispersion and health impacts based upon individual wildfire events selected to be representative of different management scenarios. For those events, we modeled smoke conveyance to downwind communities from representative future fires using the BlueSky smoke dispersion model. Lastly, we estimated human health impacts resulting from the modeled smoke using the U.S. Environmental Protection Agency's BenMAP model. Our results suggest that emissions from wildfires will substantially increase in future decades; however, increased levels of forest thinning could substantially reduce those emissions and harmful health impacts from large wildfires. We also found that increased use of prescribed burning could reduce the health impacts associated with large wildfires but would also increase the frequency of low levels of emissions. Furthermore, the modeling results suggested that individual prescribed fires could have substantial health impacts if dispersion conditions are unfavorable. Our results suggest that increased management is likely to yield important benefits given expected increases in wildfire activity associated with climate change. However, there remain many challenges to projecting the effects of alternative management regimes, especially ones that involve substantial increases in intentional burning.

Not waiting for the death knell: a pilot study to examine supplementation and survivorship in a declining population of Tasmanian eastern quoll (Dasyurus viverrinus)

Tasmanian populations of the eastern quoll (Dasyurus viverrinus) represent the last wild stronghold of this species after its extirpation from the Australian mainland, but they have experienced declines of more than 50% over the past three decades. We investigated the feasibility of supplementing wild populations with captive-bred individuals in attempts to halt and reverse observed declines in Tasmanian populations. We released 20 captive-bred eastern quolls into an extant wild population in the Tasmanian central plateau, and monitored their short-term survival, dispersal and body condition. We recorded high initial survival and low initial dispersal of captive-bred individuals relative to previous release attempts in unfenced areas of mainland Australia. Further work to determine long-term survival of released individuals, and the genetic and population-level impacts on local populations is ongoing. Our preliminary results support the use of population supplementation as an effective conservation action, which allows for early intervention to address species declines while testing hypotheses about their underlying causes.

IMPROVING THE ENVIRONMENTAL SAFETY OF BOILER PLANTS CHIMNEYS

The study results of heat engineering and environmental indicators of emissions from chimneys of gas-consuming heating boiler plants equipped with systems for deep heat recovery of exhaust gas are presented. The issues of the application heat methods efficiency to prevent condensate formation in these pipes to improve the environmental safety of chimneys when using heat-recovery technologies are considered. Methods such as partial bypassing of boiler exhaust gases past heat-recovery equipment, drying of the exhaust gases cooled after heat-recovery in heat exchangers-gas heaters and mixing dry and heated air from the boiler house air heater into the cooled gases have been studied. The effectiveness of using these methods to improve the dispersion conditions in the environment of harmful emissions contained in the flue gases of gas-consuming boilers has been analyzed. The relative decrease in the maximum surface concentration of such harmful emissions as nitrogen and carbon oxides due to the use of specified heat methods in heat-recovery systems has been determined. Comparison of efficiency indicators of the proposed methods and their ranking to improve the conditions for the dispersion of harmful emissions by chimneys of various types is carried out. It is shown that the proposed methods, usually used for corrosion protection of boiler plants chimneys using heat-recovery technologies with deep cooling of exhaust gases, also contribute to improving (up to 32 %) of the environmental friendliness of these pipes. The ranking of the considered heat methods is carried out.

The Effects of Unfulfilled Preferential Treatment and Review Dispersion on Airbnb Guests’ Attitudes and Behavior

In sharing accommodation business such as Airbnb, while the provision of personalized amenities and services may seem like good business, hosts should be aware of the potential unintended consequences when they are not able to deliver what they promise. The present research examines how expectation gaps created by guest reviews interact with different types of preferential services to subsequently affect consumer behavior in the peer-to-peer accommodation economy. Grounded in attribution theory, this study offers new insights on customer responses to unfulfilled preferential treatment. The results suggest that in the condition of utilitarian services (e.g., airport transportation), participants in the low dispersion condition exhibited more negative attitudes, a lower level of repurchase intention, and a decreased willingness to write an online review. Conversely, in the condition of hedonic services (e.g., perform a talent show), expectation discrepancy did not result in different consumer evaluations across the dispersion conditions.