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Global warming has caused an increase in frequency and degree of heat stress over the last decades. In conventional livestock husbandry systems with insulated buildings, mechanical ventilation systems and high stocking density pigs and poultry can be more affected by climate change than in free range husbandry systems. To reduce heat stress in livestock buildings, adaptation measures are used. This article assesses a wide variety of adaptation measures including energy-saving air treatment systems, which cool the inlet air (e.g. cooling pads, earth-air-heat exchanger), the use of certain building elements (e.g., insulation), optimising building characteristics (e.g., spatial orientation), modification of the indoor climate at the animal level (e.g., fogging, cooling the drinking water, increasing air velocity), and adaptation of livestock management (e.g., reduction of stocking density). The efficacy of some of these measures was quantified using simulation models and then used as a benchmark for assessing the efficacy of other measures. The efficacy of the various adaptation measures varies widely: air treatment devices which are cooling the inlet air showed the highest performance, while measures aimed at reducing the heat release of the animals (e.g., lower animal density, higher ventilation rate) performed poorest. In confined livestock systems, the reduction of heat stress by implementing adaptation measures will reduce economical losses. The selection of appropriate adaptation measures, in addition to improving animal welfare, can also be seen as a contribution to strengthen the economic resilience of farmers.

Airborne emissions from concentrated animal feeding operations (CAFOs) have the potential to pose a risk to human health and the environment. Here, we present an assessment of the emission, dispersion, and health-related impact of ammonia and hydrogen sulfide emitted from a 300-head, full-scale dairy farm with an exercise yard in Beijing, China. By monitoring the referred gas emissions with a dynamic flux chamber for seven consecutive days, we examined their emission rates. An annual hourly emission time series was constructed on the basis of the measured emission rates and a release modification model. The health risk of ammonia and hydrogen sulfide emissions around the dairy farm was then determined using atmospheric dispersion modeling and exposure risk assessment. The body mass-related mean emission factors of ammonia and hydrogen sulfide were 2.13 kg a−1 AU−1 and 24.9 g a−1 AU−1, respectively (one animal unit (AU) is equivalent to 500 kg body mass). A log-normal distribution fitted well to ammonia emission rates. Contour lines of predicted hourly mean concentrations of ammonia and hydrogen sulfide were mainly driven by the meteorological conditions. The concentrations of ammonia and hydrogen sulfide at the fence line were below 10 μg m−3 and 0.04 μg m−3, respectively, and were 2–3 orders of magnitude lower than the current Chinese air quality standards for such pollutants. Moreover, the cumulative non-carcinogenic risks (HI) of ammonia and hydrogen sulfide were 4 orders of magnitudes lower than the acceptable risk levels (HI = 1). Considering a health risk criterion of 1E-4, the maximum distance from the farm fence line to meet this criterion was nearly 1000 m towards north-northeast. The encompassed area of the contour lines of the ambient concentration of ammonia is much larger than that of hydrogen sulfide. However, the contour lines of the ammonia health risk are analogous to those of hydrogen sulfide. In general, the ammonia and hydrogen sulfide emissions from the dairy farm are unlikely to cause any health risks for the population living in the neighborhood.

Economic risks for livestock production are caused by volatile commodities and market conditions, but also by environmental drivers such as increasing uncertainties due to weather anomalies and global warming. These risks impact the gross margin of farmers and can stimulate investment decisions. For confined pig and poultry production, farmers can reduce the environmental impact by implementing specific adaptation measures (AMs) to reduce heat stress. A simulation model driven by meteorological data was used to calculate indoor climate for 1981 to 2017. This dataset was extrapolated for a projection in the year 2030. The heat stress was calculated for a business-as-usual livestock building and for several AMs. For 2030, the expected value of the reduction of the gross margin was calculated by EUR 3.98 a−1 per animal place for the business-as-usual scenario. The results show that only energy-saving adaptation measures to reduce the inlet air temperature are appropriate to reduce the economic risk to the level of the year 1980 between EUR 0.03 a−1 and EUR 1.02 a−1 per animal place. The efficiency of other AMs to reduce heat stress is distinctly lower (between EUR 2.62 a−1 and EUR 3.80 a−1 per animal place). The results in this study can support the decision making of farmers concerning adaptation management and investments. It can inform agricultural policy design as well as technological development.

Regarding air quality, odours have been repeatedly ranked as the number one reason for public complaints to authorities. The most widely used method for assessing odour impacts is dispersion modelling. However, the entire impact assessment chain is permeated with uncertainty, and the role of different sources of uncertainty is not well understood. A critical component of this chain is the emission, the focus of this work. Here we develop modelling analyses for examining the influence of variable emissions against constant emissions on the outcomes of impact assessments. The analyses are built upon six hourly-resolved emission scenarios and one time-invariant scenario applied for the fattening phase of pig production systems. All seven scenarios are configured to treat total emissions due to a mechanically ventilated shed as coming from an elevated point source with an unobstructed vertical release. A total of 378 impact maps from three sites in two countries (Austria and the U.S.) over relatively flat terrain are scrutinised. The influence and relevance of accounting for variability in odour emissions over time depend strongly on the nature of the emissions (e.g., temporal pattern, presence of stochastic and deterministic components) as well as other factors such as building downwash, odour impact criterion and stack height. Altogether, the results suggest that using hourly odour emission rates can improve the confidence in impact assessments compared with the simulations driven by constant emissions. For odour impact criteria based on high-end percentiles, the assumption of constant emissions can be more easily compromised. In contrast, lower percentiles are found to be more robust in offsetting the source emission variability. Results also indicate that the variability in odour emissions might become less of an issue for releases under the influence of downwash than those without obstacle effects. This systematic work is the largest investigation to date on the consequences of incorporating variable emissions when modelling odour impacts. Our findings demonstrate that the emission scenario used as input to dispersion models can play a central role in dictating the conclusions of odour impact assessments.

In biogas plants, where biological treatment of organic matter by anaerobic digestion (AD) is performed, as well as in plants for upgrading of biogas to biomethane, there might be emissions to air from different parts of the plants. Precise and comparable methods to quantify methane (CH4) emissions from biogas plants are necessary to evaluate mitigation strategies and to generate more accurate emissions factors for national emission inventories in the context of the United Nations Framework Convention on Climate Change (UNFCCC) reporting. The main objective of this study was to provide recommendations for the measurement and modelling procedures of inverse dispersion modelling (IDM) to assure comparability of CH4 emissions among diverse approaches and AD facilities. Two Lagrangian stochastic dispersion models were used operating in forward (LASAT) and backward (WindTrax) mode based on open-path concentration and meteorological data acquired by three international measurement teams at two biogas plants. The sensitivity analysis of the modelling systems regarding input parameters and setups (e.g. source configuration, terrain, sampling distance from the site, different combinations of wind data) showed that in WindTrax (backward mode) the measurement speed of meteorological parameters (via three-dimensional ultrasonic anemometer) had the largest influence on the calculated emission estimates, while in LASAT (forward mode) the assumption of the source configuration greatly affected the flux estimates. The used concentration data (e.g. location of observations, measurement mode of background concentration) was critically important to the success of IDM. The CH4 emission rates from the AD facility in flat terrain (plant 1) calculated with both Lagrangian models by IDM showed good agreement with the DIAL (Differential Absorption Light Detection And Ranging) method and methane release tests (deviation in the range of 10–20%) when using best fit configurations (e.g. volume source in LASAT, area source in WindTrax, optimal measurement fetch). In moderately complex terrain (plant 2), the retrieval rates of controlled CH4 releases, and thus the certainty of flux estimates of both dispersion models tended to decrease without the use of a terrain model.

Pigs and poultry are raised predominantly at high stocking densities in confined, insulated livestock buildings with mechanical ventilation systems. These systems are quite sensitive to heat stress, which has increased in recent decades from anthropogenic warming. A dataset of hourly meteorological data from 1981 to 2017 was used to drive a steady-state balance model for sensible and latent heat that simulates the indoor climate of a conventional reference system, and this model was used to predict the effect of global warming on growing-fattening pigs housed in such livestock confinement buildings. Seven adaptation measures were selected to investigate the effect on the indoor climate; these measures included three energy-saving air preparation systems, a doubling of the maximum ventilation rate, a reduction in the stocking density, and a shift in the feeding and resting time patterns. The impact of heat stress on animals was calculated with the following three heat stress metrics: a threshold of the indoor temperature, the temperature-humidity index, and a body mass–adapted temperature. The seven adaptation measures were quantified by a reduction in factors of the heat stress parameters. The highest reduction of heat stress in comparison with the conventional reference system was achieved by the three air preparation systems in the range of 54 to 92% for adiabatic systems and 65 to 100% for an earth-air heat exchanger, followed by an increase in the ventilation rate and the time shift. The reduction in the stocking density showed the lowest improvement. In addition to the reduction in the heat stress, a temporal trend over three decades was also used to quantify the resilience of pig confinement systems. The efficacy of some of the adaptation measures is great enough to mitigate the increase of heat stress that occurs due to global warming.

This study examined climate change impacts (CCI) on productivity of pig production systems, their resource use, environmental impacts and the relevance of potential adaptation options. The impact of increasing temperature and temperature-humidity index (THI) on performance of pigs in confined housing systems was analysed by a meta-analysis. Using climate data for an Austrian site for the period 1981 to 2010, different scenarios (cold year, warm year, hot year, worst case scenario) were modelled and compared. Although significant differences between thermoneutral and heat stress conditions were detected for the analysed traits of growing and finishing pigs, overall performance, resource use (cumulative energy demand) and environmental impacts (global warming, acidification and eutrophication potential) per kg of live mass for finished pigs and reared piglets did not significantly differ between most scenarios. Elements of pig production systems resilient to CCI, which were not considered under performance and environmental impacts (LCA), were addressed in a system analysis that was based on literature and expert knowledge. The most important detected system elements are plants and animals with an appropriate genetic potential, securing the access to inexpensive feed, including land for feed production, securing water supply and the implementation of health plans and measures against diseases associated with CCI.

Short-term events are one of the specific aspects that differentiate odour nuisance problems from conventional air quality pollutants. Atmospheric dispersion modelling has been considered the gold standard to realise odour impact assessments and to calculate separation distances. Most of these models provide predictions of concentrations of a pollutant in ambient air on an hourly basis. Even when the hourly mean odour concentration is lower than the perception threshold, concentration peaks above the threshold may occur during this period. The constant peak-to-mean factor is nowadays the most widespread method for evaluating short-term concentrations from the long-term ones. Different approaches have been proposed in the scientific literature to consider non-constant peak-to-mean factors. Two prominent approaches to do so are the i) variable peak-to-mean factor which considers the distance from the source and atmospheric stability and the ii) concentration-variance transport. In this sense, the aim of this work is to compare the results of three different freely available dispersion models (namely, CALPUFF, LAPMOD and GRAL), which implement three distinct ways to evaluate the short-term concentration values. Two sites, one in Austria and the other in Italy, were selected for the investigation. Dispersion model results were compared and discussed both in terms of long-term (hourly) concentrations and short-term. An important outcome of this work is that the dispersion models provided more equivalent results for hourly mean concentrations, in particular in the far-field. On the contrary, the method to evaluate short-term concentrations can deliver disparate results, thereby revealing a potential risk of poor assessment conclusions. The utilistion of a multiangle methodological approach (dispersion models, study site locations, algorithms to incorporate short-term concentrations) allowed providing useful information for future studies and policymaking in this field. Accordingly, our findings call for awareness on how the use of a particular dispersion model and its sub-hourly peak calculation method can affect odour impact assessment conclusions and compliance demonstrations.

In the mid-latitudes, pigs and poultry are kept predominantly in confined livestock buildings with a mechanical ventilation system. In the last decades, global warming has already been a challenge which causes hat stress for animals in such systems. Heat stress inside livestock buildings was assessed by a simulation model for the indoor climate, which is driven by meteorological parameters. Besides the meteorological conditions, the thermal environment inside the building depends on the sensible and latent energy release of the animals, the thermal properties of the building and the ventilation system and its control unit. For a site in Austria in the north of the Alpine Ridge, which is representative for confined livestock buildings for growing-fattening pigs in Central Europe, meteorological data between 1981 and 2017 were used for the model calculations of heat stress measures. This business-as-usual simulation over these 37 years resulted in an increase of the mean relative annual heat stress parameters in the range between 0.9 and 6.4% per year since 1981. In order to minimise the negative economic impact as the consequence of this positive trend of heat stress, adaptation measures are needed. The calculations for growing-fattening pigs show that such a simulation model for the indoor climate is an appropriate tool to determine the level of heat stress of livestock inside confined livestock buildings.

Transported Saharan dust creates a substantial natural background to particulate matter concentrations in Central Europe. The contributions by Saharan dust are especially detectable at Alpine mountain sites, where many other sources have little impact. The ability of a chemical weather forecasting model to simulate dust transport is of vital interest, as serious health effects due to this phenomenon, similar in scale to those resulting from nuclear or industrial accidents, wildfires, pollen, etc., may require countermeasures. Thus, we investigate whether the WRF-Chem model set-up, which is run operationally for air quality forecasts in Austria, can accurately predict the transport of the Saharan dust cloud towards Central Europe in April 2016. WRF-Chem simulations with and without desert dust emissions reveal that whenever PM concentrations were high during the three periods of this event, 60–70% of the dust arriving at the Eastern Alps originated in the desert. The measurements and model results deliver a detailed picture of the course of this extraordinary dust event, with successive peaks over the Eastern Alpine region. Using this long-lasting Saharan dust event as an example, a structured step-wise approach is proposed to investigate peak dust episodes based on data analysis of representative background sites, source area analysis by means of Lagrangian dispersion modelling, and coupled meteorological and chemical modelling.

Ammonia and odour are the most relevant pollutants emitted from livestock buildings used for monogastric animal production. Whereas odour can cause annoyance in the close vicinity of the source, emission of ammonia is a precursor for the formation of particulate matter and acidification on a regional scale. Because of clean air regulation in Europe, total ammonia emissions reduced by 23% between 1990 and 2015 whilst, over the same period, anthropogenic warming became more and more evident. By a simulation of the indoor climate of a confined livestock building with a mechanical ventilation for 1800 fattening pigs, the modification of the odour and ammonia emission was calculated for the period between 1981 and 2017. For ammonia emission, a relative increase of 0.16% per year was determined. But following the clean air endeavour between 1990 and 2015 emissions over that period were reduced by 23%. The global warming signal counteracting this reduction in the range of 4% during over this period, which means that the overall reduction for the ammonia emission was only 19%. For Austria with a global warming increase of 1% from 1990 to 2015, this gives an increase in emissions of 5% instead. Odour emissions also increased by about 0.16% per year. The relative increase of the separation distances for the four cardinal directions was about 0.06% per year, the related increase for the separation area was 0.13% per year. This case study on the fattening pigs shows that the global warming signal has a negligible impact on separation distances.

Intensive pig and poultry production are predominantly performed in confined livestock buildings which are equipped with mechanical ventilation systems. The frequency of heat stress will increase due to climate change. Heat stress events are accompanied by performance depressions (e.g. daily weight gain, egg production, mortality, feed conversion rate). Consequently, appropriate air treatment devices can become necessary to optimise the indoor climate of confined livestock buildings because of a high inlet air temperature. In this study, we analysed the effects of three energy saving air treatment devices: (1) earth-air heat exchanger, (2) direct evaporative cooling by cooling pads, and (3) indirect evaporative cooling systems which combine evaporative cooling (e.g. by cooling pads) with a subsequent heat recovery system. All systems are compared to a reference ventilation system without air treatment, which is today's typical housing system. The results show that the earth-air heat exchanger (1) is the most efficient air treatment device. It eliminates heat stress and can also be used during wintertime to increase the inlet air temperature. The two adiabatic cooling systems (2) and (3) can reduce heat stress by about 90%. Cooling pads can lead to a high relative humidity of the inlet air between 75% and 100%, which can cause problems inside the livestock buildings, e.g. increasing the moisture content of the bedding material. The indirect cooling device can avoid this disadvantage at the expense of a reduced temperature reduction of the inlet air temperature and higher investment costs.

Odorous gases emitted from landfills have always been a public concern, but studies evaluating the odour contribution and the correlation between the odour concentrations are limited. The objectives of this study were to assess the odour contribution and to correlate the measured odour concentration C OD with the calculated odour concentration SOAV , which was calculated as sum of individual odour activity value ( OAV ). Odorous air samples from a landfill in Beijing were collected seasonally and measured by both gas chromatography and an olfactometer. Different from previous studies, we measured the odour threshold of 51 detected compounds using a uniform methodology to minimize the imprecision of citing odour threshold from disparate literature. The odour threshold is used to convert the individual chemical concentration into the OAV , which is used as a surrogate of the odour concentration. Evaluation of the OAV revealed that hydrogen sulfide (65.9%), dimethyl sulfide (14.4%) and trimethylamine (8.6%) contributed the most to the odour at the landfill. Moreover, the correlation between the calculated odour concentration SOAV and the measured odour concentration C OD resulted in a linear regression equation of C OD = 6.28 SOAV ( r = 0.914, n = 24, p K = 6.28, the average ratio of calculated odour concentration to measured odour concentration could be improved from less than 0.2 to 1.1. By the calibration of the calculated odour concentration SOAV , it is possible to use continuous measurements of chemical concentrations to derive odour concentration for this site for monitoring purposes.

In a changing climate it is expected that the predicted temperature rise will also affect wind conditions and parameters needed to determine atmospheric stability. In this paper we investigate how the changes in wind conditions and stability will affect the dispersion of airborne emissions. For odorous substances, the separation distances around livestock farms are calculated to protect the neighbourhood from odour annoyance. This is done for two Central European sites in Austria with different meteorological conditions, situated in areas with considerable livestock activity, namely around Wels in the north-alpine foreland and at Feldbach in the Raab valley south of the Alpine chain. Two climate scenarios have been used, namely the time period 1981–2010 (present climate) and the period 2036–2065 (future climate). Slight changes in wind and stability conditions for the two sites have been obtained, influencing the changes in separation distances. Although these are only minor, they show some interesting differences not expected a priori. We conclude that the climate change signal has mostly only a low impact on the separation distances. This will not substantially affect the zoning and licensing of livestock buildings in Austria in the course of this century. Keywords: Stability class, Separation distance, Odour, Climate change, Livestock

Direction-dependent separation distances to avoid odour annoyance, calculated with the Gaussian Austrian Odour Dispersion Model AODM and the Lagrangian particle diffusion model LASAT at two sites, are analysed and compared. The relevant short-term peak odour concentrations are calculated with a stability-dependent peak-to-mean algorithm. The same emission and meteorological data, but model-specific atmospheric stability classes are used. The estimate of atmospheric stability is obtained from three-axis ultrasonic anemometers using the standard deviations of the three wind components and the Obukhov stability parameter. The results are demonstrated for the Austrian villages Reidling and Weissbach with very different topographical surroundings and meteorological conditions. Both the differences in the wind and stability regimes as well as the decrease of the peak-to-mean factors with distance lead to deviations in the separation distances between the two sites. The Lagrangian model, due to its model physics, generally calculates larger separation distances. For worst-case calculations necessary with environmental impact assessment studies, the use of a Lagrangian model is therefore to be preferred over that of a Gaussian model. The study and findings relate to the Austrian odour impact criteria.

International audience; In the companion (Part I) paper, we have described and evaluated a new versatile optical particle counter/sizer named LOAC (Light Optical Aerosol Counter), based on scattering measurements at angles of 12 and 60 •. That allows for some typology identification of particles (droplets, carbonaceous, salts, and mineral dust) in addition to size-segregated counting in a large diameter range from 0.2 µm up to possibly more than 100 µm depending on sampling conditions (Renard et al., 2016). Its capabilities overpass those of preceding optical particle counters (OPCs) allowing the characterization of all kind of aerosols from submicronic-sized absorbing carbonaceous particles in polluted air to very coarse particles (> 10–20 µm in diameter) in desert dust plumes or fog and clouds. LOAC's light and compact design allows measurements under all kinds of balloons , on-board unmanned aerial vehicles (UAVs) and at Published by Copernicus Publications on behalf of the European Geosciences Union. 3674 J.-B. Renard et al.: LOAC: a counter/sizer for ground-based and balloon measurements – Part 2 ground level. We illustrate here the first LOAC airborne results obtained from a UAV and a variety of scientific balloons. The UAV was deployed in a peri-urban environment near Bordeaux in France. Balloon operations include (i) tethered balloons deployed in urban environments in Vi-enna (Austria) and Paris (France), (ii) pressurized balloons drifting in the lower troposphere over the western Mediter-ranean (during the Chemistry-Aerosol Mediterranean Experiment – ChArMEx campaigns), (iii) meteorological sounding balloons launched in the western Mediterranean region (ChArMEx) and from Aire-sur-l'Adour in southwestern France (VOLTAIRE-LOAC campaign). More focus is put on measurements performed in the Mediterranean during (ChArMEx) and especially during African dust transport events to illustrate the original capability of balloon-borne LOAC to monitor in situ coarse mineral dust particles. In particular, LOAC has detected unexpected large particles in desert sand plumes.

Governments are increasingly introducing odour impact criteria (OIC) to determine separation distances between odour sources and residential areas. Previous studies have shown the wide range of OIC available for this purpose, depending on the desired level of protection against odour annoyance. However, it is unclear whether OIC with similar levels of protection can ensure analogous separation distances, which would reasonably be expected. This study presents a comparative analysis of separation distances calculated at two sites for different OIC, but all related to an equivalent level of protection. Here, the equivalent level of protection was defined for urban residential areas (land use), swine odour (hedonic tone) and new facilities (facility type). In this manner, the regulatory criteria currently enforced in Germany, Ireland, and Queensland (Australia) were selected as references for the investigation. The results clearly show that, even for an equivalent level of protection, disparate separation distances can be obtained. Differences in separation distances were found to be greater in prevailing wind directions compared to distances in additional wind directions. Overall, the results demonstrate a risk of poor conclusions in odour assessments. This means that care must be taken when adopting OIC for decision making, principally in those countries that have not yet established specific regulations to manage environmental odours. Concomitantly, the results stress the need for better harmonisation of the concept of the odour impact criterion and components thereof. By using perturbation analysis, it has also been found that the stack exit temperature influences the separation distances in a distinct way, reliant on the criteria used to determine the distances. This finding is of significance for input data collection in future odour modelling studies. Furthermore, approaches used to derive OIC, equivalence between dispersion modelling and field inspections (European standard EN 16841-1), as well as implications of the findings for regulatory practice are summarised and discussed.

Continuous odour measurements both of emissions as well as ambient concentrations are seldom realised, mainly because of their high costs. They are therefore often substituted by concentration measurements of odorous substances. Then a conversion of the chemical concentrations C (mg m-3) into odour concentrations COD (ouE m-3) and odour intensities OI is necessary. Four methods to convert the concentrations of single substances to the odour concentrations and odour intensities of an odorous mixture are investigated: (1) direct use of measured concentrations, (2) the sum of the odour activity value SOAV, (3) the sum of the odour intensities SOI, and (4) the equivalent odour concentration EOC, as a new method. The methods are evaluated with olfactometric measurements of seven substances as well as their mixtures. The results indicate that the SOI and EOC conversion methods deliver reliable values. These methods use not only the odour threshold concentration but also the slope of the Weber-Fechner law to include the sensitivity of the odour perception of the individual substances. They fulfil the criteria of an objective conversion without the need of a further calibration by additional olfactometric measurements., accepted for publication on Dec. 20, 2015, Atmospheric Environment (2016)

Die Messung von Treibhausgasemissionen bei biologischen Abfallbehandlungsanlagen, insbesondere von Methan (CH4), stellt eine wichtige Voraussetzung dar, die Relevanz dieser Emissionen verlasslich zu beurteilen bzw. auch Masnahmen zu rechtfertigen, um diese Emissionen vermeiden zu konnen. Bei der Erhebung emittierter Methanfrachten sind vor allem jene Standorte problematisch, bei denen grose Mengen an diffusen Emissionen auftreten, da diese messtechnisch bisher nur mit sehr hohem Aufwand oder uberhaupt ungenugend quantifizierbar sind. Am Institut fur Abfallwirtschaft (Universitat fur Bodenkultur Wien) wird derzeit eine mikrometeorologische Methode in Verbindung mit einem optischen Fernmessgerat (open-path Tunable Diode Laser Absorption Spectroscopy – OP-TDLS) fur emissionsrelevante Fragestellungen bei Deponien und anderen abfallwirtschaftlichen Anlagen (Biogasanlagen, Nachrotteflachen von mechanisch-biologischen Abfallbehandlungsanlagen, Kompostierungsanlagen etc.) angewandt. Anhand von zwei Fallstudien wird das Potenzial dieser Quantifizierungsmethode zur Emissionsbewertung von Kompost- bzw. Vergarungsanlagen dargestellt. Mithilfe dieser Methode konnen grose Flachen schnell optisch abgescannt werden, ohne die Gasflusse an der Oberflache bzw. Austrittsstelle zu beeinflussen. Die Ergebnisse zeigen, dass die CH4-Freisetzung von Biogasanlagen bzw. Kompostwerken im Tagesverlauf stark schwankt. Aufgrund der langen Messperioden konnten die Emissionen sowohl betriebstechnisch als auch meteorologisch interpretiert werden. Verglichen mit herkommlichen, punktuellen Messmethoden (z. B. Haubenmessung) konnten diffuse und temporare Quellen durch das optische Fernmesssystem einfacher und uber einen langeren Zeitraum hinweg erfasst werden.

Dispersion models are a common means to calculate separation distances around odour sources to protect the neighbourhood from odour nuisance. As the models usually calculate half-hourly or hourly averages of concentrations, they have to account somehow for the ability of the human nose to perceive odour within a single breath. For this purpose, the authors have developed and already published a peak-to-mean approach used with the Austrian Odour Dispersion Model (AODM), a Gaussian model adapted for the prediction of odour sensation. This approach is here used also with the Lagrangian particle diffusion model LASAT in a post-processing mode. Both models can now calculate direction-dependent separation distances for a prescribed combination of odour threshold and exceedence probability which are a function of the prevailing atmospheric stability conditions. This is demonstrated for a rural site in the Austrian flatlands east of Vienna. In addition, separation distances are also determined for an odour threshold of 0.25 (factor 4) of the German TA Luft (Technical Guideline for Clean Air) uniquely applied over all stability conditions and distances. The resulting separation distances and their implications when using these approaches with the two models are presented and discussed.

In recent years, there has been a growing concern about potential impacts on public health and wellbeing due to exposure to environmental odour. Separation distances between odour-emitting sources and residential areas can be calculated using dispersion models, as a means of protecting the neighbourhood from odour annoyance. This study investigates the suitability of using one single year of meteorological input data to calculate reliable direction-dependent separation distances. Accordingly, we assessed and quantified the inter-annual variability of separation distances at two sites with different meteorological conditions, one in Brazil and the other in Austria. A 5-year dataset of hourly meteorological observations was used for each site. Two odour impact criteria set in current regulations were selected to explore their effect on the separation distances. The coefficient of variation was used as a statistical measure to characterise the amount of annual variation. Overall, for all scenarios, the separation distances had a low degree of inter-annual variability (mean coefficient of variation values from 8% to 21%). Reasonable agreements from year to year were therefore observed at the two sites under investigation, showing that one year of meteorological data is a good compromise to achieve reliable accuracy. This finding can provide a more cost-effective solution to calculate separation distances in the vicinity of odour sources.

To determine separation distances between odour sources and residential areas to avoid odour nuisance and complaints by the residents, odour impact criteria OIC have to be adopted by the responsible authorities. There is a wide variety of OIC used for this purpose, which differ by the odour concentration threshold between 0.12 ou m−3 and 10 ou m−3 and by the tolerated exceedance probability of this threshold between 0.1% and about 35%. For two national OIC for a protection level of rural residential areas (Ireland with a threshold of 6 ou m−3 and an exceedance probability of 2% and Germany 0.25 ou m−3/20%) and two national OIC fur urban residential areas (Ireland: 3 ou m−3/2%, Germany 0.25 ou m−3/13.6%), the direction depending separation distances were calculated, and the similarity to 166 various OIC was investigated. The large discrepancies among the national OIC provokes the question if separation distances calculated for the same protection level are then still comparable and thus meet general expectations or not. For this comparison the normalised mean standard error was selected as a statistical measure. There are two groups of OIC used in various jurisdictions: The first one with a low odour concentration threshold and a high exceedance probability evaluating ambient odour intensity close to the perception threshold (Germany) and the second group of the remaining countries with high odour intensity by using a high concentration threshold and a low exceedance probability. The direction depending separation distances of OIC with the same protection level can vary considerably. The OIC of the last group, evaluating higher ambient odour intensities, show a much lower sensitivity to site specific meteorological data. Therefore a higher exceedance probability seems more appropriate for the determination of OIC. Even if the similarity of separation distances by various OIC could be determined, the direction dependent separation distances differ considerably for the same protection level.

For the assessment of odour annoyance by dispersion models, the odour emission rate of the source has to be known. In general, an annual mean value is used, although the live mass of the animals increases dramatically during the fattening period and odour emission from the building is known to depend strongly on indoor air temperature and ventilation rate. This annual mean value of the odour emission rate was compared with various emission scenarios for a continuous flow production system with a constant live mass of 75 kg and an all-in/all-out system. For the last one an inverse transfer sampling method was used to avoid an interaction between the growth of the animals and the annual variation of the outdoor temperature. The variation of the emission factor was taken into account twofold, first by a schematized diurnal emission pattern for the various seasons and second by a steady state simulation model that employs a sensible heat balance to calculate indoor temperature and ventilation rate which both influence the odour release. The results indicate an underestimation of the odour emission rate of a livestock building during summer compared with winter when using an annual mean value. For the all-in/all-out system, this effect is superposed by an overestimation at the beginning of the fattening period and an underestimation at the end. Using the emission model which takes into account a time series of the odour emission rate, a more realistic description of the odour emission characteristics can be achieved compared with an annual mean value.

Open digestate storage tanks were identified as one of the main methane (CH4) emitters of a biogas plant. The main purpose of this paper is to determine these emission rates using an inverse dispersion technique in conjunction with open-path tunable diode laser spectroscopy (OP-TDLS) concentration measurements for multisource reconstruction. Since the condition number, a measure of "ill-conditioned" matrices, strongly influences the accuracy of source reconstruction, it is used as a diagnostic of error sensitivity. The investigations demonstrate that the condition number for a given source-sensor configuration in the highly disturbed flow field within the plant significantly depends on the meteorological conditions (e.g., wind speed, stratification, wind direction, etc.). The CH₄ emissions are retrieved by removing unrepresentative periods with high condition numbers, which indicate uncertainty in recovering the individual sources. In a final step, the CH₄ emissions are compared with the maximum biological methane potential (BMP) in the digestate analyzed under laboratory conditions. The retrieved methane emission rates represent an average of 50% of the maximum BMP of the stored digestate in the winter months, while they comprised an average of 85% during the measurement campaigns in the summer months. The results indicate that the open tanks have the potential to represent a substantial emission source even during colder periods.

The impact of ambient concentrations in the vicinity of a plant can only be assessed if the emission rate is known. In this study, based on measurements of ambient H2S concentrations and meteorological parameters, the a priori unknown emission rates of a tannery wastewater treatment plant are calculated by an inverse dispersion technique. The calculations are determined using the Gaussian Austrian regulatory dispersion model. Following this method, emission data can be obtained, though only for a measurement station that is positioned such that the wind direction at the measurement station is leeward of the plant. Using the inverse transform sampling, which is a Monte Carlo technique, the dataset can also be completed for those wind directions for which no ambient concentration measurements are available. For the model validation, the measured ambient concentrations are compared with the calculated ambient concentrations obtained from the synthetic emission data of the Monte Carlo model. The cumulative frequency distribution of this new dataset agrees well with the empirical data. This inverse transform sampling method is thus a useful supplement for calculating emission rates using the inverse dispersion technique.

In this paper, two approaches to estimate odour concentrations in dispersion models are compared. The approaches differ in the estimation of the momentary (peak) odour concentration for the time interval of a single human breath (approximately 5 s). The Austrian Odour Dispersion Model (AODM) is a Gaussian model with peak-to-mean factors depending on wind speed and atmospheric stability. The German Lagrange code AUSTAL2000 uses a constant factor 4 in all meteorological conditions to derive the maximum odour concentration over a short integration time. As the Lagrange model, in contrast to the Gauss model, can be applied also in complex topography and with isolated buildings, the implementation of the Austrian peak-to-mean approach in AUSTAL2000 would enable for more realistic separation distances in these environments. In a current scientific project, this implementation will be carried out, and a comparison of separation distances with AODM and AUSTAL2000 will be undertaken.

Biologically relevant exposure to environmental pollutants often shows a non-linear relationship. For their assessment, as a rule short term concentrations have to be determined instead of long term mean values. This is also the case for the perception of odour. Regulatory dispersion models like AUSTAL2000 calculate long term mean concentration values (one-hour), but provide no information on the fluctuation from this mean. The ratio between a short term mean value (relevant for odour perception) and the long term mean value (calculated by the dispersion model), called the peak-to-mean value, is usually used to describe these fluctuations. In general, this ratio can be defined in different ways. Janicke et al. (2012) , in a comment to Schauberger et al. (2012) which includes a statement that AUSTAL2000 uses a constant factor of 4, argue that AUSTAL2000 does not apply a peak-to-mean factor and does not calculate odour exceedance probabilities. Instead it calculates the frequency of so-called odour-hours by applying the relation between the 90-percentile of the instantaneous concentration and the hourly mean ( Janicke and Janicke, 2007a ), not between some peak value and the mean. According to Janicke and Janicke (2007a) , the 90-percentile of the instantaneous concentration can in practice be estimated with sufficient accuracy from the hourly mean by using a factor of 4. Having so far replied to Janicke et al. (2012) we take additionally the opportunity to elaborate a little more on the peak-to-mean concept, especially pointing out that a constant factor independent of the stability of the atmosphere, the distance from and the geometry of the source, is not appropriate. On the contrary it shows a sophisticated structure which cannot be described by only one single value.