Dispersion modeling of odour, gases, and respirable dust using AERMOD for poultry and dairy barns in the Canadian Prairies

For determining setback distances considering multiple air pollutants, a comprehensive study was conducted to simulate the atmospheric dispersion of odour, ammonia (NH₃), hydrogen sulfide (H₂S), and respirable dust using an US EPA air dispersion model AERMOD for a commercial dairy, broiler, and cage-layer barn in the Canadian Prairies. The simulation was conducted using five years of meteorological data. Setback distances were determined with the input of varying monthly emission rates of all four air pollutants and odour impact criteria specifically developed for all three odour sources. Results showed the layer barn had the greatest odour impact area (maximum 3023 m for an annual average odour concentration of 0.01 OU m^-3) followed by the broiler and dairy barns. Due to the prevailing south wind for all three barns, odour traveled farthest in the north. Using the suggested odour impact criteria by the Government of Saskatchewan defined for all odour sources, maximum setback distances were decreasing from 1941 to 641 m for the layer barn and from 980 to 320 m for the broiler barn along with the increasing of odour concentration (OC) thresholds (1-6 OU m^-3), all in the north direction. While for the dairy barn, setback distances were determined only under an OC limit of 1 OU m^-3; maximum 205 m in the north and minimum 171 m in the south. Using the newly developed odour impact criteria specifically for the three odour sources, maximum setback distance of 558 m in the north was determined for the layer barn under an odour threshold of 9 OU m^-3. Additionally, the results suggest the use of odour impact criteria for determining setback distance rather than using gas/respirable threshold limits set in ambient air quality standards as the former always requires much greater setback distances than the latter.

Filling in sewage sludge biodrying gaps: Greenhouse gases, volatile organic compounds and odour emissions

In the present work, a complete study of the sewage sludge (SS) biodrying technology was conducted at bench-scale, aiming at assessing its performance and providing a valuable insight into the different gaseous emission patterns found for greenhouse gases (GHG) and odorant pollutants. As process key parameters, temperature, specific airflow, dynamic respiration index, final moisture content and Lower Calorific Value (LCV) were evaluated. At the end of the biodrying, a product with a 35.9% moisture content and a LCV of 7.1 MJ·kg^-1product was obtained. GHGs emission factor was 28.22 kgCO_2eq per Mg of initial mass of dry matter in the SS (DM₀-SS). During the biodrying process, maximum odour concentration measured was 3043 ou·m^-3 and the estimated odour emission factor of the biological treatment was 3.10E + 07 ou per Mg DM₀-SS. Finally, VOCs were completely identified and quantified. The most abundant VOCs found in the biodrying gaseous emissions were terpenes, sulphur-compounds and ketones.

Contaminants migrating from crossed-linked polyethylene pipes and their effect on drinking water odour

The formation potential of contaminants diffusing from cross-linked polyethylene (PE-X) pipes and their impact on the odour of drinking water was determined. Three types of PE-X material, Pe-Xa, PE-Xb and PE-Xc, were extensively assessed by performing migration tests following EN 1420 and EN 12873-1. Migration waters were analysed for their threshold odour number (TON). The same samples were investigated by two gas chromatography-mass spectrometry methods: screening and olfactometry. Most of the PE-X materials failed the German regulation of TON <2 for cold water and TON ≤4 for warm water. PE-Xb material caused the strongest odour and also released the highest amount of contaminants. Metilox, 7,9-di-tert-butyl-1-oxaspiro(4,5)deca-6,9-diene-2,8-dione, 3,5-di-tert-butyl-4-hydroxybenzaldehyde and 2,6-di-tert-butyl-p-benzoquinone (2,6-DtBQ) were the most often detected substances leaching from the tested plastic materials. However, no odour was perceived for most of these substances. Methyl tert-butyl ether (MtBE) and 2-tert-butylphenol are believed to contribute to the sensory problem in the migration water among other substances such as tert-amyl methyl ether, 2,2,2,5-tetramethyltetrahydrofuran, toluene or xylene. In total ten specific descriptions characterized the odour of the individual contaminants: ethereal, fresh, solvent, sweet, fruity, floral, unsavoury, pungent, aromatic and chemical.

Establishing the extent of odour plumes and buffers for waste handling facilities

Odour is a significant challenge for regulators of waste handling facilities due to the increasing demand for land surrounding these facilities. Many sites, including landfills, composters, abattoirs and rendering plants, that were once isolated are now close to residential areas. In some cases, this has contributed to odour impacts on residents living in those areas. Authorities have been reliant on odour modelling and odour design criteria to predict or estimate the distance at which impacts are likely to occur on sensitive land use. However, it is increasingly evident that reliance on modelling tools, and the estimated odour emission rates used in modelling, are not reflecting ground level observations. Environment Protection Authority Victoria ("EPA") conducted six in-field odour monitoring campaigns between 2007 and 2017. We studied these six campaigns to understand the extent of odour plumes from waste handling facilities. The campaigns used odour surveillance methodology developed by EPA. They consisted of in-field odour assessments around common waste handling facilities such as composters, landfills, abattoirs and rendering plants. We used the results of surveillance in conjunction with reverse trajectory plotting to estimate the typical extent and frequency of odour plumes as a function of distance. The study showed that the application of consistent in-field odour assessment methodologies improved understanding of odour plumes, and hence increases the options available to manage impacts.

Odorous emission reduction from a waste landfill with an optimal protection system based on fuzzy logic

Effective landfill management and operation require an accurate evaluation of the occurrence and extent of odour emission events, which are among the main causes of resident complaints and concerns, in particular in densely urbanised areas. This paper proposes a fuzzy optimal protection system (FOPS) based on fuzzy logic to manage odour production from a municipal solid waste (MSW) landfill. The case study is a MSW landfill in an old quarry site located 6 km north-west of Naples city centre (Italy). The aim is to reduce the odour nuisance in the area surrounding the landfill where there are several sensitive receptors. FOPS is based on logical relationships between local atmospheric dynamics, number and intensity of odour pollution events detected by certain fixed receptors and odour emission rate via an optimal fuzzy approach. Such system allows to start, in real time, established mitigation actions required to further reduce the odorous emissions from the landfill itself (e.g. spraying of perfumed substances and activation of extraction wells), especially when weather conditions might not be favourable and cause by causing a higher odour perception. The fuzzy system was coupled with the air pollutant transport software CALPUFF to simulate the odour dispersion in the considered area taking into account both different odour emission rates and local weather conditions. FOPS results show that this approach can be very useful as, by measuring the odour concentrations, a significant reduction of the odour exceedances over the thresholds fixed, to minimise the olfactory harassment, was observed in the whole area studied.

Trickling filter technology for biotreatment of nitrogenous compounds emitted in exhaust gases from fishmeal plants

Odour emissions are a major environmental issue associated with fishmeal production. Laboratory-scale biotrickling filters (BTFs) were inoculated with microbial consortia derived from sewage sludge, with the goal to study the biotreatment of low-loads of methylamines and ammonia that are main components of odorous exhaust gases produced by fishmeal processing plants. A BTF packed with ceramic rings was subjected to a real fishmeal plant emission containing trimethylamine (TMA), dimethylamine (DMA) and monomethylamine (MMA). The highest elimination capacities (ECs) obtained were 372 mg TMA m^-3 h^-1, 5.518 mg DMA m^-3 h^-1 and 1.038 mg MMA m^-3 h^-1, with maximal removal efficiencies of 92% (TMA), 83% (DMA) and 95% (MMA) after 30 days operation. In a different experiment, a polyurethane foam packing was employed to treat ammonia (NH₃) at low inlet loads, reaching an EC of 47.19 mg N m^-3 h^-1 with 99.8% efficiency (inlet load of 47.27 mg N m^-3 h^-1). Likewise, the microbial community of the polyurethane-associated biofilm was diverse and stable during operation. These results suggested that elimination of volatile amino-compounds using BTFs inoculated with a methylotrophic microbial consortium holds potential for odour removal. In addition, sequencing analysis of 16S rDNA gene fragments allowed the identification of heterotrophic ammonia-oxidizing bacteria that are promising candidates to effectively maintain ammonia elimination in a biotreatment operation of nitrogenous compounds present in exhaust gases from fishmeal facilities.

Understanding the effect of ventilation, intermittent pumping and seasonality in hydrogen sulfide and methane concentrations in a coastal sewerage system

Gas pollutants emitted during wastewater transport contribute to atmospheric pollution, aggravated risks for utility workers, infrastructure corrosion, and odour nuisance. Field studies have shown that is difficult to effectively obtain reliable correlations between in-sewer air movement and gas pollutant concentrations. This study aimed at investigating the influence of different ventilation and operating conditions in H₂S and CH₄ horizontal and vertical movement in a section of a gravity sewer, downstream of a pumping station. Relevant liquid and gas phase quality parameters were monitored, and significant H₂S concentrations were measured (with lower contents of CH₄). Results evidenced that headspace temperature and ventilation played a key effect when analysing H₂S and CH₄ dynamics. Setups with a similar content of sulfide and chemical oxygen demand resulted in different H₂S and CH₄ headspace concentrations. It was also observed that an increase in ventilation resulted in a decrease of average headspace relative humidity of over 70%, with clear implications in corrosion potential estimates. Another interesting observation was that the wastewater drag induced by intermittent pumping, in absence of ingassing, originated pressure differences of up to 0.2 Pa m^-1 between studied manholes. This differential originated a wave pattern of gas moving upstream and downstream, thus resulting in several gas peaks per pumping event, at the same sections. In addition, in confined setups, full mixing was not observed along the manholes.

Formation of odorous and hazardous by-products from the chlorination of amino acids

The formation of odorous aldehydes and N-chloraldimines, and also nitriles, which are potentially hazardous to human health, was investigated in studies of the chlorination of amino acids (AAs) in both operational drinking water treatment plants and laboratory-based experiments. In the drinking water treatment plants studied, the concentration of total free AAs did not significantly change after treatment, even though good removal of DOC was observed. However, free AAs still contributed less than 3% of total nitrogen in the treated drinking waters, and no aldehydes, N-chloraldimines or nitriles of interest were detected in the treated waters, presumably due to the low concentrations of the precursor AAs in these water samples. Laboratory formation potential experiments showed that carboxylic acids can form from the degradation of aldehydes and nitriles. Volatile carboxylic acids could result in odour issues and some carboxylic acids may be of potential health concern. Therefore, carboxylic acids should also be considered as potential by-products of interest in distribution systems with long contact times of ≥ 7days. A higher proportion of nitrile formation, and promotion of carboxylic acid formation, was observed when the chlorine to AA ratio was greater than 4 compared to when this ratio was 2.8, indicating that the Cl:AA ratio is an important factor in DBP formation pathways. This suggests that results from laboratory formation studies undertaken at these low Cl:AA ratios cannot be directly applied to 'real' water systems, which typically have Cl:AA ratios that are orders of magnitude higher than 4. Laboratory formation potential experiments also showed that the short-term rate of formation of aldehydes and N-chloraldimines was reduced in the presence of ammonia, although formation over longer timescales (e.g. 7 days) was not significantly different between chlorination and chloramination experiments. Therefore, the use of chloramination instead of chlorination does not appear to reduce the formation of these by-products from AAs.

Host Decoy Trap (HDT) with cattle odour is highly effective for collection of exophagic malaria vectors

BACKGROUND

As currently implemented, malaria vector surveillance in sub-Saharan Africa targets endophagic and endophilic mosquitoes, leaving exophagic (outdoor blood-feeding) mosquitoes underrepresented. We evaluated the recently developed host decoy trap (HDT) and compared it to the gold standard, human landing catch (HLC), in a 3 × 3 Latin square study design outdoors in western Kenya. HLCs are considered to represent the natural range of Anopheles biting-behaviour compared to other sampling tools, and therefore, in principle, provide the most reliable profile of the biting population transmitting malaria. The HDT incorporates the main host stimuli that attract blood-meal seeking mosquitoes and can be baited with the odours of live hosts.

RESULTS

Numbers and species diversity of trapped mosquitoes varied significantly between HLCs and HDTs baited with human (HDT-H) or cattle (HDT-C) odour, revealing important differences in behaviour of Anopheles species. In the main study in Kisian, the HDT-C collected a nightly mean of 43.2 (95% CI: 26.7-69.8) Anopheles, compared to 5.8 (95% CI: 4.1-8.2) in HLC, while HDT-H collected 0.97 (95% CI: 0.4-2.1), significantly fewer than the HLC. Significantly higher proportions of An. arabiensis were caught in HDT-Cs (0.94 ± 0.01; SE) and HDT-Hs (0.76 ± 0.09; SE) than in HLCs (0.45 ± 0.05; SE) per trapping night. The proportion of An. gambiae (s.s.) was highest in HLC (0.55 ± 0.05; SE) followed by HDT-H (0.20 ± 0.09; SE) and least in HDT-C (0.06 ± 0.01; SE). An unbaited HDT placed beside locales where cattle are usually corralled overnight caught mostly An. arabiensis with proportions of 0.97 ± 0.02 and 0.80 ± 0.2 relative to the total anopheline catch in the presence and absence of cattle, respectively. A mean of 10.4 (95% CI: 2.0-55.0) Anopheles/night were trapped near cattle, compared to 0.4 (95% CI: 0.1-1.7) in unbaited HDT away from hosts.

CONCLUSIONS

The capability of HDTs to combine host odours, heat and visual stimuli to simulate a host provides the basis of a system to sample human- and cattle-biting mosquitoes. HDT-C is particularly effective for collecting An. arabiensis outdoors. The HDT offers the prospect of a system to monitor and potentially control An. arabiensis and other outdoor-biting mosquitoes more effectively.

Pilot-scale biofiltration at a materials recovery facility: The impact on bioaerosol control

This study investigated the performance of four pilot-scale biofilters for the removal of bioaerosols from waste airstreams in a materials recovery facility (MRF) based in Leeds, UK. A six-stage Andersen sampler was used to measure the concentrations of four groups of bioaerosols (Aspergillus fumigatus, total fungi, total mesophilic bacteria and Gram negative bacteria) in the airstream before and after passing through the biofilters over a period of 11 months. The biofilters achieved average removal efficiency (RE) of 70% (35 to 97%) for A. fumigatus, 71% (35 to 94%) for total fungi, 68% (47 to 86%) for total mesophilic bacteria and 50% (-4 to 85%) for Gram negative bacteria, provided that the inlet concentration was high (10³-10⁵ cfu m^-3), which is the case for most waste treatment facilities. The performance was highly variable at low inlet concentration with some cases showing an increase in outlet concentrations, suggesting that biofilters had the potential to be net emitters of bioaerosols. The gas phase residence time did not appear to have any statistically significant impact on bioaerosol removal efficiency. Particle size distribution varied between the inlet and outlet air, with the outlet having a greater proportion of smaller sized particles that represent a greater human health risk as they can penetrate deep into the respiratory system where gaseous exchange occurs. However, the outlet concentrations were low and would further be diluted by wind in full scale applications. In conclusion, this study shows that biofilters designed and operated for odour degradation can also achieve significant bioaerosol control in waste gas.

Alternating pure oxygen and air cycles for the biostabilization of unsorted fraction of municipal solid waste

Biostabilisation is a process of treating the unsorted fraction of municipal solid waste (UFMSW) mechanically pre-treated. Although concepts such as circular economy would seem to limit biostabilization, several authors have recently described the advantages of biostabilization in regions where recycling systems are inadequate. In this perspective, the development of new MBT technologies is of considerable importance. The objective of the study was to evaluate the effects of the use of alternating air and oxygen cycles on the treated waste stability as well as on the quality of leachate and process gaseous emissions. Two Herhof biocells were prepared for this purpose. One implemented the conventional process and the other the "Air + O₂" process. The biostabilization of the inlet UFMSW (3965 ± 1965 mgO₂/kgVS/h) resulted in a final product with a dynamic respirometric index almost equal in both processes. The mass balance indicated that of the 400 tons representing the input waste, 37.57% were biostabilized waste, 0.29% leachate and 62.14% CO₂ and odours. However, the biostabilized waste was lower than that of the conventional process (equal to 40.18%). The Air + O₂ system resulted in a shorter duration, increased production of leachate (although characterized by higher quality) and process gaseous emissions quality. The energy balance (20.3 kJ/kg per input waste) and cost analysis (80.0 €/ton per input waste) showed values equal or better to those of the conventional system. By contrast, weakness was in the O₂ diffusion system. Although a life cycle analysis is necessary, the results highlighted the feasibility of the proposal especially for emergency situations.

Odours and incontinence: What does the nose know?

The fear of producing malodours that can be detected by others is a daily cause of anxiety for millions of people with incontinence. For many, the risk-whether real or imagined-that leaked waste products will be detectable by odour is sufficiently concerning to result in limitations on many types of activities. However, worry about personal odours can sensitise our olfactory system and cause us to be more aware of odours that may otherwise not be perceptible. In addition, heightened olfactory attention can often lead to odour misattributions, such as when we erroneously identify our body as the source of an odour that may simply be present in the environment. Odours produced by our bodies (endogenous odours) do enjoy a greater access to emotional brain centers and are processed faster than general odours. Here we provide examples from both everyday life and laboratory studies to explain how and why the olfactory system is unique among our sensory systems and how this knowledge can provide insights to our concerns about smell and incontinence and inform the development of products and solutions for incontinence.

Human exposure to hydrogen sulphide concentrations near wastewater treatment plants

The hydrogen sulphide (H₂S) levels from wastewater treatment plants (WWTPs) in Curitiba, Brazil have been quantified for the first time. H₂S generated by anaerobic decomposition of organic matter in WWTPs is a cause for concern because it is an air pollutant, which can cause eye and respiratory irritation, headaches, and nausea. Considering the requirement for WWTPs in all communities, it is necessary to assess the concentrations and effects of gases such as H₂S on populations living and/or working near WWTPs. The primary objective of this study was to evaluate the indoor and outdoor concentration of H₂S in the neighbourhood of two WWTPs located in Curitiba, as well as its human health impacts. Between August 2013 and March 2014 eight sampling campaigns were performed using passive samplers and the analyses were carried out by spectrophotometry, presenting mean concentrations ranging from 0.14 to 32μgm^-3. Eleven points at WWTP-A reported H₂S average concentrations above the WHO recommendation of 10μgm^-3, and 15 points above the US EPA guideline of 2μgm^-3. At WWTP-B the H₂S concentration was above US EPA guideline at all the sampling points. The I/O ratio on the different sampling sites showed accumulation of indoor H₂S in some instances and result in exacerbating the exposure of the residents. The highest H₂S concentrations were recorded during the summer in houses located closest to the sewage treatment stations, and towards the main wind direction, showing the importance of these factors when planning a WWTP. Lifetime risk assessments of hydrogen sulphide exposure showed a significant non-carcinogenic adverse health risk for local residents and workers, especially those close to anaerobic WWTPs. The data indicated that WWTPs operated under these conditions should be recognized as a significant air pollution source, putting local populations at risk.

Survey of the effect of odour impact on communities

In the context of environmental malodour, surveys are valuable as they allow for the relatively detailed analysis of multiple factors pertaining to odour perception and subsequent reaction. However, the causes for an individual to experience odour impact while a neighbour will not are still not understood. The goal of this current survey design was to consolidate varying research paths for surveys within the environmental odour research space. This survey investigated the area of effect for wastewater treatment plants by using stratified random sampling techniques that radiated from the industrial areas. Additionally, this survey provided a "non-alerted" response to environmental malodour that represents a step forward for ecological validity. We found a small number of items relating to odour annoyance and home ownership that can be used in order to predict odour impact for individual community members. However, we also did not find any relationship with odour impact and perceived control. This survey design and analysis reconciles the varied approaches towards community surveys administered in prior literature, as well as providing information to improve future community engagement policies.

Characterisation of volatile organic compounds (VOCs) released by the composting of different waste matrices

The complaints arising from the problem of odorants released by composting plants may impede the construction of new composting facilities, preclude the proper activity of existing facilities or even lead to their closure, with negative implications for waste management and local economy. Improving the knowledge on VOC emissions from composting processes is of particular importance since different VOCs imply different odour impacts. To this purpose, three different organic matrices were studied in this work: dewatered sewage sludge (M1), digested organic fraction of municipal solid waste (M2) and untreated food waste (M3). The three matrices were aerobically biodegraded in a bench-scale bioreactor simulating composting conditions. A homemade device sampled the process air from each treatment at defined time intervals. The samples were analysed for VOC detection. The information on the concentrations of the detected VOCs was combined with the VOC-specific odour thresholds to estimate the relative weight of each biodegraded matrix in terms of odour impact. When the odour formation was at its maximum, the waste gas from the composting of M3 showed a total odour concentration about 60 and 15,000 times higher than those resulting from the composting of M1 and M2, respectively. Ethyl isovalerate showed the highest contribution to the total odour concentration (>99%). Terpenes (α-pinene, β-pinene, p-cymene and limonene) were abundantly present in M2 and M3, while sulphides (dimethyl sulphide and dimethyl disulphide) were the dominant components of M1.

Distribution and sensorial relevance of volatile organic compounds emitted throughout wastewater biosolids processing

A diverse range of volatile organic compounds (VOCs) are emitted from wastewater biosolids processing. Odorous emissions are predominately made up of volatile sulfur compounds (VSCs) which are typically the only odorants measured. However, a range of VOCs are known to contribute to malodours yet previous studies often overlook the contribution of VOCs in comparison with VSCs. This study aims to evaluate how emissions are affected by different biosolids processing configurations, and if any non-sulfur VOCs should be included in odour measurement and management. Non-sulfur VOCs emitted from biosolids throughout six wastewater treatment plants in the Sydney, Australia region were measured at six locations on average twice each week over 2-3weeks at each site. Variations in types of VOCs emitted throughout and between the sites were assigned to differences in WWTP processing configurations, plant operation and variations in industrial and municipal flows to the sewer network, referred to as sewer catchments. The presence of VOCs is likely due to biotic generation as well as industrial or residential additions to the sewer network. The dewatered and stored biosolids samples had the highest levels of VOC emissions. Sensorially important odorants were p-cresol and butanoic acid, based on the frequency of detection and odour activity values. Other compounds with a high risk of nuisance impacts were trimethylamine, indole and phenol emitted from the dewatered and stored biosolids, and volatile fatty acids from the anaerobic digester inlet and outlet at one particular site. The findings show that non-sulfur VOCs should be added to odorant monitoring campaigns at WWTPs. Identification of VOCs as sensorially important odorants opens opportunities for the more efficient management of nuisance odours, through targeted odour control or process improvement.

Volatile compounds and odour characteristics of seven species of dehydrated edible seaweeds

The volatile fraction of dehydrated edible seaweeds belonging to seven species (Himanthalia elongata, Laminaria ochroleuca, Palmaria palmata, Porphyra umbilicalis, Saccharina latissima, Ulva lactuca and Undaria pinnatifida) was analyzed by gas chromatography-mass spectrometry, after solid-phase microextraction of samples. Thirty-six hydrocarbons, 34 ketones, 28 aldehydes, 23 alcohols, 8 carboxylic acids, 6 halogenated compounds, 4 furans, 3 esters, 2 sulphur compounds, 2 pyrazines, 1 pyridine and 1 amine were detected among the 151 volatile compounds found in seaweeds. There were significant differences between seaweed species for all the volatile compounds. Hydrocarbons reached their highest levels in U. pinnatifida, ketones in P. umbilicalis, aldehydes in P. palmata and P. umbilicalis, alcohols in P. umbilicalis, carboxylic acids in S. latissima, and halogenated compounds in L. ochroleuca and S. latissima. Sensory analysis revealed that P. palmata, U. lactuca and H. elongata were the seaweeds showing the most potent seafood odour and seaweed odour characteristics.

Vapor intrusion risk of fuel ether oxygenates methyl tert-butyl ether (MTBE), tert-amyl methyl ether (TAME) and ethyl tert-butyl ether (ETBE): A modeling study

Vapor intrusion of synthetic fuel additives represents a critical yet still neglected problem at sites contaminated by petroleum fuel releases. This study used an advanced numerical model to investigate the vapor intrusion potential of fuel ether oxygenates methyl tert-butyl ether (MTBE), tert-amyl methyl ether (TAME), and ethyl tert-butyl ether (ETBE). Simulated indoor air concentration of these compounds can exceed USEPA indoor air screening level for MTBE (110μg/m³). Our results also reveal that MTBE has much higher chance to cause vapor intrusion problems than TAME and ETBE. This study supports the statements made by USEPA in the Petroleum Vapor Intrusion (PVI) Guidance that the vertical screening criteria for petroleum hydrocarbons may not provide sufficient protectiveness for fuel additives, and ether oxygenates in particular. In addition to adverse impacts on human health, ether oxygenate vapor intrusion may also cause aesthetic problems (i.e., odour and flavour). Overall, this study points out that ether oxygenates can cause vapor intrusion problems. We recommend that USEPA consider including the field measurement data of synthetic fuel additives in the existing PVI database and possibly revising the PVI Guidance as necessary.

Continuous measurement of atmospheric reduced sulphur compounds as key tracers between odour complaints and source apportionment

Odour complaints are frequent nowadays, particularly nearby industrial facilities emitting odorous compounds. Among all compounds susceptible of causing odour annoyance, reduced sulphur compounds (RSC) were studied, due to their unpleasant odour and low odour threshold. RSC ambient air mixing ratios, meteorological conditions and population complaints were analysed in an area of complex topography in order to identify their potential sources. Mixing ratios of three compounds, dimethyl sulphide (DMS), carbon disulphide (CDS) and dimethyl disulphide (DMDS), were continuously monitored using an online gas chromatograph coupled with a mass spectrometer detector (GC-MSD), which was placed in a mobile air quality monitoring unit. Measurement campaigns were performed during 2012 and 2013 for periods of 7-25 days in an urban area (four campaigns, N = 1368) and an urban area surrounded by industrial activities (three campaigns, N = 564). During such campaigns, RSC mixing ratios were frequently above their odour thresholds, which did not always involve citizen complaints. Average RSC ambient air mixing ratios tended to be lower in the urban area (DMS 0.06-0.33, CDS 0.05-0.10, DMDS 0.07-0.30 μg m^-3) than in the industry surrounded one (DMS 0.30-2.39, 0.05-0.18, DMDS 0.09-0.62 μg m^-3). The DMS/DMDS mixing ratio was frequently above 1, being a paper mill one of the main sources of RSC in the area. DMS/DMDS ratios below 1 were also recorded, suggesting a waste treatment plant as the RSC source or older air masses coming from the paper mill.

A review of odour impact criteria in selected countries around the world

Exposure to environmental odour can result in annoyance, health effects and depreciation of property values. Therefore, many jurisdictions classify odour as an atmospheric pollutant and regulate emissions and/or impacts from odour generating activities at a national, state or municipal level. In this work, a critical review of odour regulations in selected jurisdictions of 28 countries is presented. Individual approaches were identified as: comparing ambient air odour concentration and individual chemicals statistics against impact criteria (maximum impact standard); using fixed and variable separation distances (separation distance standard); maximum emission rate for mixtures of odorants and individual chemical species (maximum emission standard); number of complaints received or annoyance level determined via community surveys (maximum annoyance standard); and requiring use of best available technologies (BAT) to minimize odour emissions (technology standard). The comparison of model-predicted odour concentration statistics against odour impact criteria (OIC) is identified as one of the most common tools used by regulators to evaluate the risk of odour impacts in planning stage assessments and is also used to inform assessment of odour impacts of existing facilities. Special emphasis is given to summarizing OIC (concentration percentile and threshold) and the manner in which they are applied. The way short term odour peak to model time-step mean (peak-to-mean) effects is also captured. Furthermore, the fundamentals of odorant properties, dimensions of nuisance odour, odour sampling and analysis methods and dispersion modelling guidance are provided. Common elements of mature and effective odour regulation frameworks are identified and an integrated multi-tool strategy is recommended.

Performance, litter quality and gaseous odour emissions of broilers fed phytase supplemented diets

The effect of graded levels of phytase on performance, bone characteristics, excreta/litter quality and odorant emissions was examined using 720 Ross 308 male d-old broilers. A 2 × 4 factorial arrangement of treatments was employed with 6 replicates of 15 birds per pen. Factors were: diets-positive and negative control (PC, NC); phytase – 0, 500, 1,000, 1,500 FTU/kg. The PC was formulated to meet the 2014 Ross 308 nutrient specifications, whereas the NC was formulated with lower Ca (−1.4 g/kg), available P (−1.5 g/kg), Na (−0.3 g/kg), dLys (−0.2 g/kg) and MEn (−0.28 MJ/kg) equivalent to nutrient matrix values for 500 FTU/kg phytase in the starter, grower and finisher periods (i.e., downspec diet). On d 24, phytase decreased FCR by 1.6, 4.3 and 4.6 points at inclusion levels of 500, 1,000 and 1,500 FTU/kg, respectively (P < 0.01) across all diets. Phytase by diet interactions on BW gain were observed on d 24 and 35 (P < 0.01). The effect of phytase was much more pronounced in the NC diet as compared with the PC diet. On d 24, phytase increased BW gain by 37, 55 and 68 g in the PC and 127, 233 and 173 g in the NC at 500, 1,000 and 1,500 FTU/kg, respectively. Diet by phytase interactions were also observed for tibia ash, litter quality and water to feed intake ratio (P < 0.01) with higher phytase effect in NC as compared with PC. Neither diet nor phytase impacted excreta moisture content on d 18 or 21 (P > 0.05). Solid phase micro-extraction gas chromatography-mass spectrometry (SPME-GC-MS) analysis of gaseous emissions on d 39 indicated no difference in the emission of alcohols, aldehydes, ketones, volatile fatty acids and phenols between treatments (P > 0.05). The results indicate that phytase has greater benefits when formulated using nutrient matrix values as compared with adding it over the top in an already nutrient sufficient diet. The later method would be expected to increase feed costs without concomitant performance benefits.

Behavioural responses of Pacific salmon to chemical disturbance cues during the spawning migration

Many fish that are exposed to a threat release disturbance cues, which are chemicals that alert conspecifics to the presence of the threat. The release of disturbance cues has been well demonstrated in various species of laboratory-reared fish. Migratory fish species often exhibit increased cortisol levels and are exposed to numerous stressors during their migrations, which could trigger the release of disturbance cues. We tested the responses of wild migrating sockeye salmon (Oncorhynchus nerka) and pink salmon (O. gorbuscha) to the odours of disturbed and undisturbed conspecifics to determine whether these fish release disturbance cues following exposure to a simulated stressor. Furthermore, we tested the responses of sockeye salmon to water-borne cortisol, following evidence from past studies that this chemical is excreted through the gills of stressed fish, and speculation that endogenous correlates of stress might function as disturbance cues. We found that sockeye salmon avoid the odour of disturbed conspecifics, whereas pink salmon do not. Avoidance occurred in both female and male sockeye salmon, and was associated with an increase in plasma cortisol levels in females, but not in males. We also found no behavioural response to water-borne cortisol, which suggests this chemical does not act as an exogenous disturbance cue in sockeye salmon. Avoidance of disturbed conspecifics could limit exposure to risks during the sockeye salmon spawning migration, but could also delay the rate of migration and thereby accrue reproductive costs.

Effect of reuterin-producing Lactobacillus reuteri coupled with glycerol on the volatile fraction, odour and aroma of semi-hard ewe milk cheese

The effect of the biopreservation system formed by Lactobacillus reuteri INIA P572, a reuterin-producing strain, and glycerol (required for reuterin production), on the volatile fraction, aroma and odour of industrial sized semi-hard ewe milk cheese (Castellano type) was investigated over a 3-month ripening period. The volatile compounds were extracted and analyzed by SPME-GC-MS and cheese odour and aroma profiles were studied by descriptive sensory analysis. Control cheese was made only with a mesophilic starter and experimental cheeses with L. reuteri were made with and without glycerol. The addition of L. reuteri INIA P572 to milk enhanced the formation of six volatile compounds. Despite the changes in the volatile compounds profile, the use of L. reuteri INIA P572 did not noticeably affect the sensory characteristics of cheese. On the other hand, the addition of L. reuteri INIA P572 coupled with 30mM glycerol enhanced the formation of twelve volatile compounds, but decreased the formation of five ones. The use of the biopreservation system did not affect overall odour and aroma quality of cheese although it resulted in a significant decrease of the odour intensity scores. In addition, this cheese received significant higher scores for "cheesy" aroma and significant lower scores for the aroma attributes "milky", "caramel" and "yogurt-like". The first two axes of a principal component analysis (PCA) performed for selected volatile compounds and sensory characteristics, accounting for 75% of the variability between cheeses, separated cheeses made with L. reuteri INIA P572 and glycerol from the rest of cheeses, and also differentiated control cheese from cheeses made with L. reuteri INIA P572 from day 60 onward. Our results showed that the reuterin-producing L. reuteri INIA P572 strain, when coupled with glycerol, may be a suitable biopreservation system to use in cheese without affecting odour and aroma quality.

Olfactory Specific Satiety depends on degree of association between odour and food

The pleasantness of a food odour decreases when that food is eaten to satiety or even smelled for a brief period (Olfactory Specific Satiety, OSS), which suggests that odours signal food variety and encourage approach behaviour toward novel foods. In the study here, we aimed to extend this theory to understand the consequence of manipulating the food consumed and its degree of association to the evaluated odour. We also wished to clarify if these effects related to individual sensitivity to the target odour. In the study here, participants (n = 94) rated the pleasantness of a food odour (isoamyl acetate) and then consumed confectionary that had either Low or High association to that odour or a No food control. This was followed by final pleasantness ratings for the odour and a threshold sensitivity test. Results revealed that in line with OSS, pleasantness decreased in the High association group only. This effect was not dependent on any differences in sensitivity to the target odour. These findings are consistent with OSS, and that this effect likely depends on activation of brain areas related to odour hedonics rather than the degree to which the odour is detected.