Photocatalytic degradation of trinitrotoluene and other nitroaromatic compounds

The photocatalytic degradation of 2,4,6-trinitrotoluene and ten other nitroaromatic compounds in aerated TiO₂ suspensions has been studied. The following order of reactivity was observed: nitrotoluenes > nitrobenzene > dinitrotoluenes . dinitrobenzenes > 2,4,6-trinitrotoluene > 1,3,5-trinitrobenzene, which reflects the known influence of nitro groups towards the attack of electrophilic reagents on the aromatic molecule.     

(M)VOC and composting facilities. Part 1: (M)VOC emissions from municipal biowaste and plant refuse

GOAL, SCOPE AND BACKGROUND: Malodorous volatiles derived from the decomposition of biowaste within the process of composting might pose a risk to human health. Different techniques of process engineering have been developed to minimise the burden of malodorous compounds in air possibly affecting compost workers and residents in the vicinity. METHODS: In the present study, three different composting facilities were examined for the emission of volatiles to estimate the impact of process engineering on the dispersal of odorous compounds and to discuss its relevance for human health. RESULTS AND DISCUSSION: Concentrations of single compounds belonging to alcohols, ketones, furanes, sulfur-containing compounds and especially terpenes ranged from 10(2) up to nearly 10(6) ng/m3 depending on the sampling sites and the process engineering. The ratio of MVOC and total VOC measured changed throughout the process of biodegradation. A certain combination of volatile compounds coincided with the occurrence of typical compost odour. CONCLUSION: The type of process engineering seemed to have a major impact on the emission of volatiles, as amounts of (microbial) volatiles emitted were characteristic for the different techniques used. Thus, the MVOC emission basically depends on the degree of biodegradation. It is likely that the concentrations workers are exposed to can have an impact on human health. RECOMMENDATIONS AND OUTLOOK: It is obvious that less sophisticated types of process engineering give rise to greater amounts of bioaerosols and volatiles and, therefore, technical devices have to be improved and controlled regularly to minimise adverse health effects on workers.     

Analysis of particle-associated semi-volatile aromatic and aliphatic hydrocarbons in urban particulate matter on a daily basis

PM_2.5 Particle-associated semi-volatile organic compounds (SVOC) were determined in the city of Augsburg, Germany. Daily samples were collected at a central monitoring station from late summer to late autumn 2002. The concentrations of polycyclic aromatic hydrocarbons (PAH), oxidized PAH (O-PAH), n-alkanes, hopanes and long chain linear alkylbenzenes were determined by direct thermal desorption-gas chromatography-time of flight mass spectrometry (DTD-GC-TOFMS). Additionally, PM_2.5 particle mass and number concentrations were measured. The sampling campaign can be divided into two parts, distinguished by a lower temperature level in the second part of the campaign. The particulate mass concentration showed no significant changes, whereas most of the SVOC had significant higher mean and peak concentrations in the colder period. The analysis of the data showed an increased influence of non-traffic sources in the colder period, reflected by a weak shift in the PAH profile and a significant shift in the hopane pattern. Statistical analysis of the inter-group correlations was carried out. Eight clusters partly representing different sources of the aerosol have been identified.     

Communal nesting is explained by subsequent mating rather than kinship or thermoregulation in the Siberian flying squirrel

Research on group living in animals is concentrated on highly social species, but studying less social species may hint at the factors possibly leading to the evolution of increased sociality. Thermoregulation is often thought to explain communal nesting in solitarily breeding mammals but also other factors may be involved. For example, it is observed that even solitary species may have cryptic kin cooperation. We studied factors affecting communal nesting in the Siberian flying squirrel. Flying squirrels breed solitarily but, similar to most other rodents, adults may sometimes huddle in groups. Communal nesting in flying squirrels was most frequent during winter and autumn, but also occurred during other seasons. This pattern was explained by the breeding season, which took place in the spring–summer, when communal nesting was less common. Neither monthly temperature, after accounting for breeding season, nor daily temperatures in winter explained communal nesting. Group size was small, two to three individuals. In most cases the group was a pair consisting of unrelated male and female, possibly indicating that group formation was related to mating behavior. This study contributes to the understanding of mammalian group formation in two major ways. First, our study contributes to the understanding of the role of relatedness in rodent group formation, demonstrating a case where close relatedness is not related to group formation. Second, our study indicates that in a solitarily breeding, rodent huddling may be more driven by other factors than temperature.     

Three-dimensional characterization of the ammonia plume from a beef cattle feedlot

In Canada approximately 45% of ammonia (NH₃) emissions are attributed to dairy and beef cattle industries. The present study focused on NH₃ emissions from a beef feedlot with a one-time capacity of 17,220 head. The aim was to improve the Canadian NH₃ emission inventories and air quality forecasting capabilities. A Cessna 207, equipped with a fast-response NH₃/NO_y detector and a quadrupole aerosol mass spectrometer, was flown in a grid pattern covering an area of 8 × 8 km centered on a feedlot (800 × 800 m) at altitudes ranging from 30 to 300 m above ground. Stationary ground measurements of NH₃ concentration and turbulence parameters were made downwind of the feedlot. Three flights were conducted under varying meteorological conditions, ranging from very calm to windy with near-neutral stratification. NH₃ mixing ratios up to 100 ppbv were recorded on the calm day, up to 300 m above ground. An average feedlot NH₃ emission rate of 76 ± 4 μg m^?2 s^?1 (equivalent to 10.2 g head^?1 h^?1) was estimated. Characteristics of the measured NH₃ plume were compared to those predicted by a Lagrangian dispersion model. The spatially integrated pattern of NH₃ concentrations predicted and measured agreed but the measured was often more complex than the predicted spatial distribution. The study suggests that the export of NH₃ through advection accounted for about 90% of the emissions from the feedlot, chemical transformation was insignificant, and dry deposition accounted for the remaining 10%.     

Oxygenated polycyclic aromatic hydrocarbons in atmospheric particulate matter: Molecular characterization and occurrence

Particulate matter (PM) has become a major research issue receiving increasing attention because of its significant negative impact on human health. There are main indicators that next to the morphological characteristics of the particle, also the chemical composition plays an important role in the adverse health effects of PM. In this context, the rather polar organic fraction of PM is expected to play a major role, and advanced analytical techniques are developed to improve the knowledge on the molecular composition of this fraction. One component class that deserves major attention consists of the oxygenated polycyclic aromatic hydrocarbons (PAHs). Those compounds are considered to be among the key compounds in PM toxicity. This paper presents a comprehensive review focusing on the analysis, fate and behavior of oxygenated PAHs in the atmosphere. The first part of the paper briefly introduces (i) the main sources and atmospheric pathways of oxygenated PAHs, (ii) available physical–chemical properties and (iii) their health effects. The second and main part of this paper gives a thorough discussion on the entire analytical sequence necessary to identify and quantify oxygenated PAHs on atmospheric PM. Special attention is given to critical parameters and innovations related to (i) sampling, (ii) sample preparation including both extraction and clean-up, and (iii) separation and detection. Third, the state-of-the-art knowledge about the atmospheric occurrence of oxygenated PAHs is discussed, including an extended overview of reported concentrations presented as a function of sampling season and geographical location. A clear seasonal effect is observed with the median of the oxygenated PAHs concentrations during winter being a factor of 3–4 higher than during summer. However, the oxygenated PAH/parent PAH ratio is about 20 times higher during summer, indicating the importance of photochemical activity in the atmosphere.     

Gamma-dose rates from terrestrial and Chernobyl radionuclides inside and outside settlements in the Bryansk Region, Russia in 1996-2003

In order to estimate current external gamma doses to the population of the Russian territories contaminated as a result of the Chernobyl accident, absorbed gamma-dose rates in air (DR) were determined at typical urban and suburban locations. The study was performed in the western districts of the Bryansk Region within the areas of 30 settlements (28 villages and 2 towns) with the initial levels of 137Cs deposition ranging from 13 to 4340 kBqm(-2). In the towns, the living areas considered were private one-story wooden and stone houses. DR values were derived from in situ measurements performed with the help of gamma-dosimeters and gamma-spectrometers as well as from the results of soil samples analysis. In the areas under study, the values of DR from terrestrial radionuclides were 25+/-6, 24+/-5, 50+/-10, 32+/-6, 54+/-11, 24+/-8, 20+/-6, 25+/-8, and 18+/-5 nGyh(-1) at locations of kitchen gardens, dirt surfaces, asphalt surfaces, wooden houses, stone houses, grasslands inside settlement, grasslands outside settlement, ploughed fields, and forests, respectively. In 1996-2001, mean normalized (per MBqm(-2) of 137Cs current inventory in soil) values of DR from (137)Cs were 0.41+/-0.07, 0.26+/-0.13, 0.15+/-0.07, 0.10+/-0.05, 0.05+/-0.04, 0.48+/-0.12, 1.04+/-0.22, 0.37+/-0.07, and 1.15+/-0.19 microGyh(-1) at the locations of kitchen gardens, dirt surfaces, asphalt surfaces, wooden houses, stone houses, grasslands inside settlement, grasslands outside settlement, ploughed fields, and forests, respectively. The radiometric data from this work and the values of occupancy factors determined for the Russian population by others were used for the assessments of annual effective doses to three selected groups of rural population. The normalized (per MBqm(-2) 137Cs current ground deposition) external effective doses to adults from 137Cs ranged from 0.66 to 2.27 mSvy(-1) in the years 1996-2001, in accordance with professional activities and structures of living areas. For the areas under study, the average external effective doses from 137Cs were estimated to be in the range of 0.39-1.34 mSvy(-1) in 2001. The average external effective doses from natural radionuclides appeared to be lower than those from the Chernobyl fallout ranging from 0.15 to 0.27 mSvy(-1).