Abstract: Undoubtedly, the most important advance in the environmental regulatory monitoring of elements of the last decade is the widespread introduction of ICP-mass spectrometry (ICP-MS) due to standards developed by the European Committee for Standardization. The versatility of ICP-MS units as a tool for the determination of major, minor and trace elements (Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, P, Pb, Sb, Se, Sn, Ti, V and Zn) in surface water, groundwater, river sediment, topsoil, subsoil, fine particulates and atmospheric deposition is illustrated in this paper. Ranges of background concentrations for major, minor and trace elements obtained from a regional case study (Flanders, Belgium) are summarized for all of these environmental compartments and discussed in the context of a harmonized implementation of European regulatory monitoring requirements. The results were derived from monitoring programs in support of EU environmental quality directives and were based on a selection of (non-polluted) background locations. Because of the availability of ICP-MS instruments nowadays, it can be argued that the main hindrance for meeting the European environmental monitoring requirements is no longer the technical feasibility of analysis at these concentration levels, but rather (i) potential contamination during sampling and analysis, (ii) too limited implementation of quality control programs, validating the routinely applied methods (including sampling and low level verification) and (iii) lack of harmonization in reporting of the chemical environmental status between the individual member states.

Abstract: The aim of this study is to investigate the dispersion of ultrafine particles and its spatial distribution in a street canyon and its neighbourhood with the 3D CFD model ENVI-met®. The performance of the model at street scale is evaluated and the importance of the boundary conditions like wind field and traffic emissions on the UFP concentration is demonstrated. To support and validate the modelled results, a short-term measurement campaign was conducted in a street canyon in Antwerp, Belgium. The UFP concentration was measured simultaneously with P-TRACK (TSI Model 8525) at four different locations in the canyon. The modelled UFP concentrations compare well with the measured data (correlation coefficient R from 0.44 to 0.93) within the standard deviation of the measurements. Despite the moderate traffic flow in the street canyon, UFP concentrations in the canyon are in general double of the background concentrations, indicating the high local contribution for this particle number concentration. Some of the observed concentration profiles are not resembled by the model simulations. For these specific anomalies, further analysis is performed and plausible explanations are put forward. The role of wind direction and traffic emissions is investigated. The performance evaluation of ENVI-met® shows that in general the model qualitatively and quantitatively describes the dispersion of UFP in the street canyon study.

Abstract: A new parameterization for size resolved ultrafine particles (UFP) traffic emissions is proposed based on the results of PARTICULATES project (Samaras et al., 2005). It includes the emission factors from the Emission Inventory Guidebook (2006) (total number of particles, #/km/veh), the shape of the corresponding particle size distribution given in PARTICULATES and data for the traffic activity. The output of the model UFPEM (UltraFine Particle Emission Model) is a sum of continuous distributions of ultrafine particles emissions per vehicle type (passenger cars and heavy duty vehicles), fuel (petrol and diesel) and average speed representative for urban, rural and highway driving. The results from the parameterization are compared with measured total number of ultrafine particles and size distributions in a tunnel in Antwerp (Belgium). The measured UFP concentration over the entire campaign shows a close relation to the traffic activity. The modelled concentration is found to be lower than the measured in the campaign. The average emission factor from the measurement is 4.29E + 14 #/km/veh whereas the calculated is around 30% lower. A comparison of emission factors with literature is done as well and in overall a good agreement is found. For the size distributions it is found that the measured distributions consist of three modes Nucleation, Aitken and accumulation and most of the ultrafine particles belong to the Nucleation and the Aitken modes. The modelled Aitken mode (peak around 0.040.05 μm) is found in a good agreement both as amplitude of the peak and the number of particles whereas the modelled Nucleation mode is shifted to smaller diameters and the peak is much lower that the observed. Time scale analysis shows that at 300 m in the tunnel coagulation and deposition are slow and therefore neglected. The UFPEM emission model can be used as a source term in dispersion models.

Abstract: Mass, major ionic components (MICs) of PM2.5, and related gaseous pollutants (SO2, NOx, NH3, HNO2, and HNO3) were monitored over six locations of different anthropogenic influence (industrial, urban, suburban, and rural) in Belgium. SO42-, NO3-, NH4+, and Na+ were the primary ions of PM2.5 with averages diurnal concentrations ranging from 0.44.5, 0.37.6, 0.94.9, and 0.41.2 µg m-3, respectively. MICs formed 39% of PM2.5 on an average, but it could reach up to 8098%. The SO2, NO, NO2, HNO2, and HNO3 levels showed high seasonal and site-specific fluctuations. The NH3 levels were similar over all the sites (26 µg m-3), indicating its relation to the evenly distributed animal husbandry activities. The sulfur and nitrogen oxidation ratios for PM2.5 point towards a low-to-moderate formation of secondary sulfate and nitrate aerosols over five cities/towns, but their fairly intensive formation over the rural Wingene. Cluster analysis revealed the association of three groups of compounds in PM2.5: (i) NH4NO3, KNO3; (ii) Na2SO4; and (iii) MgCl2, CaCl2, MgF2, CaF2, corresponding to anthropogenic, sea-salt, and mixed (sea-salt + anthropogenic) aerosols, respectively. The neutralization and cation-to-anion ratios indicate that MICs of PM2.5 appeared mostly as (NH4)2SO4 and NH4NO3 salts. Sea-salt input was maximal during winter reaching up to 12% of PM2.5. The overall average Cl-loss for sea-salt particles of PM2.5 at the six sites varied between 69 and 96% with an average of 87%. Principal component analysis revealed vehicular emission, coal/wood burning and animal farming as the dominating sources for the ionic components of PM2.5.