Air pollution

Contaminant concentrations and their variability affect rate of removal of air contaminant in biofiltration. In this study with toluene as the air contaminant, extent of degradation rate at varying concentrations (from 50 to 700 ppm) in terms of elimination capacity (EC) was measured using a soil biofilter run for 215 days. It appears that no inhibition or oxygen limitation was observed at 700 ppm as EC went higher at this concentration reaching 58 g m-3 hr-1. Results show that at low toluene concentrations in the gas stream, toluene was degraded faster than it could diffuse into the biofilm while at high toluene concentrations, the whole biofilm was fully penetrated and there was no increase in EC due to biological activity limitation. Oxygen limitation may influence removal rates even if oxygen is not completely depleted in the biofilm with biofilm thickness as another factor in oxygen limitation. There was growth in the biofilm but it did not produce a biofilm thick enough to give rise to oxygen limitation. Though toluene inhibition and/or oxygen limitation could eventually become influencing factors, biofiltration may be used as an air pollution control technology at varying contaminant concentration.

Odour nuisance is the second environmental problem with more citizen complaints after noise. This fact and the lack of odour regulation in Portugal led way to develop a bottom-up approach focused on citizens to co-create the analysis. Despite the existence of odour measuring instruments, the human nose is a universal sensor with high sensitivity that allows to assess the impact of discomfort on human receptors. A sensorial method was conducted in a community neighbor of an oilseed industry that cause impact on their daily life because of the “cereal/flours/feeds” odour (based on citizens’ complaints, industry type, exploratory survey). Two monitoring campaigns were conducted with the help of a group of citizens forming an observers panel (OP) whose function was to record odour observations. A road circuit was outlined by the technical team also to register odour observations but essentially to verify the OP registers. For both cases a meteorological analysis was conducted with a weather station. Results showed that the “cereal/flours/feeds” kind of odour was registered by the OP 150 times during a six month period. The intensity level, although week, was several times perceived when the meteorological conditions were week wind and wind blowing from the northwest which led the plume towards the population.

An important aspect in the design of wind farms and consequently in wind power production, is the sensitivity of wind turbines to wind gusts. This study aims at estimating the probability of occurrence of daily wind gusts for different atmospheric circulation regimes. The analysis is performed for a 31-year period (1979-2009) for the Hellinikon station in Athens, Greece. The proposed methodology estimates wind gust speed values from the mean daily wind speed observations for a given atmospheric circulation pattern. The large-scale atmospheric circulation classification is based on a two-stage clustering approach, using Self-Organizing Maps as a clustering methodology. The classification is based on the Sea Level Pressure, the geopotential at 500hPa, the zonal and meridional wind components at 10m and at 850hPa, the specific humidity at 700hPa and the air and dew-point temperature at 2m. Following the gust factor method, different statistical models are trained for each of the eight identified atmospheric modes. The results demonstrate the suitability of associating wind gusts and mean wind speeds. The adopted gust factor method provides accurate estimates of daily wind gust speeds and that the atmospheric circulation enhances the precision of the statistical models.

This paper aims to assess the air quality improvement and resulting health implications in a Portuguese urban area, by testing traffic management scenarios focused on nitrogen dioxide (NO2) emission reduction. To that end, an integrated multiscale modelling system was developed and applied for a typical traffic-activity day using dynamical downscaling to the street level. At this finer scale, the tested scenarios contributed to a reduction of the daily maximum NO2 concentration and health benefits, though the LEZ effect is more felt within its influence area.

Odour emissions from complex industrial plants may cause potential impacts on the surrounding areas and, as consequence, complaints with the local residents. The identification of specific odour control plan is therefore needed in the plant management. The current challenge is the definition of Instrumental Odour Monitoring Systems (IOMSs) that allow the continuous odour characterization. No regulation or standardized procedure exist at present. Limited data are available in the literature with reference to the characteristics and operational procedure of this systems for the environmental odours monitoring. The study presents a novel prototype of intelligent and integrated IOMS for the continuous classification and quantification of the odours emitted in ambient air by complex industrial plants, with the scope to control the plants emissions in an objective and continuous manner, thus avoiding odour impact. The architecture and the principal components of the IOMS are highlighted. The operational procedures are presented and discussed. Results highlights the importance and the flexibility of the proposed IOMS in the odour monitoring. Real-time and accurate information are provided by the system about the source and concentration of the odour emissions.