Mean Ground Level Concentrations Research Articles

Ground level ozone (O3) associated with radon (222Rn) and particulate matter (PM) concentrations in Bucharest metropolitan area and adverse health effects

The aim of this paper is to contribute with new information in the application of ground based radon (222Rn) observations to atmospheric research, namely its relation with air pollution due to ground-level ozone (O3) and particle matter in two size fractions (PM10 and PM2.5) for Bucharest metropolitan area in Romania. During January 1–December 31, 2011, ground levels of radon, ozone and particulate matter (PM) have been continuously monitored in synergy with the main meteorological parameters (air temperature, humidity and pressure), and daily global air quality indices. A systematic analysis of surface ozone observations of ground level radon, ozone and PM is presented. Observational results indicate the following yearly daily mean ground level concentrations: 40.26 ± 7.54 Bq/m3 for radon, 90.51 μg/m3 for ozone, 35.96 μg/m3 for PM2.5, and 40.91 μg/m3 for PM10. The assessment of the results showed the influence of local and meteorological conditions on the daily mean radon, ozone and PM concentrations. However, in densely populated metropolitan area of Bucharest the mean daily values of ozone, PM2.5, PM10, and attached 222Rn are sometimes higher than European Community limit values leading to serious public concern during the last years. Due to the high risk of increased levels of O3, PM2.5, PM10, and attached 222Rn on human health respiratory function (especially for children and older persons), and urban green, the results are very useful for atmospheric, radiological protection, epidemiological and environmental studies.

Transport to ground of emissions in aircraft wakes. Part II: Effect on NO x concentrations in airport approaches

Predictions as to the transport of aircraft NO x emissions to ground level in the vicinity of an airport are made, taking account of the vortical dynamics of the aircraft wake. A model is used to calculate mean ground-level concentrations. It employs a kinematic approach, harnessing results from dynamical models in the literature. Two aircraft types are considered, a B737-300 (twin turbofan), taken as representative of short-range aircraft, and a B747-400, taken as representative of long-range aircraft. Airport and meteorological parameters are assigned values as holding in the case of Manchester Airport, UK, during a fortnight in May 1999 (prior to the opening of a second runway there). The airport operated at a capacity of about 45 aircraft movements per hour in the peak morning period, with frequencies in the middle of the day being about half this. Aircraft of maximum takeoff weight in excess of 120 tonnes accounted for some 6% of all movements. The simulations predict mean NO x concentrations of maximum 3 μg m −3 at the centre of the runway arising as a result of the vortex-mediated transport (as expressed on conversion of all NO to NO 2), with concentrations on the order of 1 μg m −3 arising 0.5 km laterally from the runway.

Emissions of mercury and other trace elements from coal-fired power plants in Japan

To evaluate trace element emissions from modern coal-fired power plants into the atmospheric environment in Japan, trace elements in the coal used in electric utility boilers, stack concentrations, emission rates and emission ratios of coal-fired power plants, and proportions of trace elements in coal-fired power plants were studied. The elements were As, B, Be, Cd, Co, Cr, F, Hg, Mn, Ni, Pb, Sb, Se and V, which are designated in the Law of Pollutant Release and Transfer Register. The particulate trace elements were collected in an electrostatic precipitator and a wet desulfurization scrubber. Emissions into the atmosphere were lower than 1% of the quantity in coal, but the volatile trace elements showed somewhat higher emission ratios. For mercury, the mean concentration in coal was 0.045 ppm, the mean emission rate was 4.4 μg/kW h, and the mean emission ratio was 27%, the highest ratio among all elements in this study. The total annual emission of mercury from coal-fired power plants of the electric power industry in Japan was estimated to be 0.63 t/y. On the basis of these data, the atmospheric environment loads from a coal-fired power station were investigated. The calculation of stack gas dispersion showed that maximum annual mean ground level concentrations were in the order of 10 − 2 to 10 − 5 of the background concentrations, and that the adverse effect of the emissions from the coal-fired power station was small.

Effects of uncertainties in parameters of a Lagrangian particle model on mean ground-level concentrations under stable conditions

This work evaluates the effects of uncertainties in five parameters or inputs of a source-receptor Lagrangian particle model on mean ground-level concentrations. The scope of work is short-range dispersion in the atmospheric boundary layer under weakly and moderately stable conditions over a smooth flat terrain within 3 km downwind from a continuous point source located near the ground. Model inputs include four meteorological parameters and the universal constant in the random component of the model. The meteorological parameters are friction velocity, mean surface turbulent heat flux magnitude (shortly, heat flux), surface roughness height (shortly, roughness height), and mean surface temperature (shortly, temperature). Model outputs of interest are mean ground-level concentrations at a number of receptors downwind from the source. The formal uncertainty analysis was performed for the atmospheric conditions corresponding to stability indices (defined as the ratio of mixing height to Monin-Obukhov length) of 1.2, 2.5, and 4.1. Input uncertainties were propagated through the model using Monte Carlo simulations with Latin hypercube sampling. Linear regression modeling was used to statistically partition an output uncertainty and determine the relative importance of an input to an output. It is shown that the concentration uncertainty increases with the level of meteorological uncertainty and that its magnitude varies with stability degree. Among the meteorological parameters, friction velocity is the most influential. Another important input is the universal constant whose contribution can dominate when the level of meteorological uncertainty becomes low. The overall contributions from roughness height and temperature are relatively small.

면/이동오염원 배출량 공간 할당방식에 대한 고찰

In the present study, space allocation methods of pollutant emission from area and mobile sources are assessed by the actual application to air quality modeling of Pohang area. It is found that the TM-based modeling which allocates emission onto the 1km x 1km sized TM-grid system predicts almost the same mean ground-level concentration as that by the GIS-based modeling which uses geographical information of area and mobile sources directly, while maximum ground-level concentration by the TM-based modeling is predicted considerably lower than that by the GIS-based modeling. Moreover, the problem is found that the TM-based modeling causes deviation of mobile roads. In conclusion, it is anticipated to applying GIS-based modeling for a more accurate assessment of air quality in local scale.

Overall properties of the heavy gas clouds in the Thorney Island phase II trials

Estimation of cloud areas, advection speeds, mean ground-level concentrations and height-scales has been carried out for three flat-ground trials and a

Groundlevel concentration fluctuations from a buoyant and a non-buoyant source within a laboratory convectively mixed layer

With the use of mixed-layer scaling, the near-surface mean concentration and the concentration fluctuations at moderate distances downwind of a stack emitting a highly buoyant effluent are obtained and compared quantitatively with those from a non-buoyant source that is otherwise identical. The environment is a laboratory mixed layer in a state of free convection with mean wind simulated by towing the stack along a horizontal line. Although the buoyant effluent has a much smaller maximum mean groundlevel concentration occurring at a greater downwind distance than the non-buoyant effluent, the decay of mean concentration from that point downwind is found to be exceedingly slow in the buoyant case. The cumulative frequency distributions of sampled concentrations greater than zero for these same two cases are found to be log-normal in only a bimodal sense, with the weaker concentrations having a greater logarithmic range in amplitude than the stronger concentrations. The ratio of the root-mean-square (r.m.s.) concentration fluctuation to the mean concentration, in the central portion of the mean plume, is found to decay with downwind distance. Homogenization associated with both downstream and vertical mixing is believed responsible for the rapid decay observed.

An application of a multiple point source atmospheric dispersion model

A multiple point-source Gaussian dispersion model designed to calculate the dispersion of industrial emissions, utilizing readily available meteorological data and suitable for use by control authorities, is described. The model has been applied to sulphur dioxide emission data from the Milford Haven area and its performance has been evaluated by comparison with National Survey monitoring data collected over a 49day period. The mean predicted concentrations for this period were found to be in reasonable agreement with those measured, the median error in prediction being of the same order as the limiting error of the measuring apparatus, namely about 7μg m −3. It was concluded that the model could be usefully employed to study the effect of proposed developments, both in isolation and in relation to other emission sources, on long period mean ground level concentrations. It could not be used for day to day control.

Ambient sulphur dioxide inventory derived from National Survey data in the Southampton neighbourhood

The daily mean SO 2 data available from 13 National Survey monitors in the Southampton Water neighbourhood were correlated with wind direction data. The directional daily SO 2 data were then analysed to determine the mean ground level concentration from an oil refinery, a power station and the city of Southampton. The drift into the area from sources outside was determined also. The long-term mean contributions from the three major emission sources accounted for 3 μg m −3 in a total mean ambient glc of 39 μg m −3. About 30 μg m −3 was accounted for by drift from outside the area, the balance, apparently, by numerous minor local sources within the area.

The transport of atmospheric pollutants across the North Sea and English Channel

Daily mean concentrations of smoke and sulphur dioxide were monitored at six coastal sites in England, Germany and Denmark. Winter mean concentrations of ammonium, chloride, nitrate and sulphate were determined from smoke filters. The observations were grouped into wind octants for each site and a mean value calculated. The results give an upper figure for the background level in unpolluted maritime air and indicate that emissions in Great Britain give rise to mean ground level concentrations on the far side of the North Sea only marginally above those due to natural sources. Concentrations in airstreams from the Continent reaching eastern England are distinctly higher, however, sometimes equalling the levels observed in urban areas. Sources as far distant as eastern Europe seem to be responsible.

A Discussion on recent research in air pollution - Variability and upper bounds for maximum ground level concentrations

The properties of the various factors which arise in the conventional formula for maximum hourly mean ground level concentration (max. g.l.c.) after fixing mean wind speed and source strength are studied with a view to assessing variability and comparing with results from the Tilbury field trial. The analysis indicates some ambiguity in defining vertical spread for dispersion from tall stacks and suggests that the formula might be more profitably rearranged. A natural rearrangement is pointed out and this leads to a simple upper bound for max. g.l.c. in an unbounded atmosphere which is only 20 % larger than the familiar result for a uniform atmosphere. This result is obtained using the diffusion equation with simple power laws for wind speed and eddy diffusivity. The general conservation equation is then considered and this leads to a specific definition of mean wind speed below source level and the indication of a general upper bound some 50 % larger than the uniform atmosphere value provided certain reasonable conditions are met. The practical implications of these results are discussed and the extra effects introduced by stable layers are pointed out.

Paper V: Properties of the maximum ground level concentration from an elevated source

Simple one and two layer models of the atmosphere are used to derive properties of the downwind position and value of the maximum in mean ground level concentration which can effect either the handling or the interpretation of field data. It is shown that this maximum is quite flat, implying that whilst the peak value can be found accurately its position will be subject to large errors. The effect of stable layers above the source is also discussed and it is indicated how much of the scatter in field results can be attributed to this cause. The distribution of maximum concentration values which arise from a simple distribution of stable layer heights is evaluated and compared with experiment.

Single Point and Relative Diffusion in Unstable Wall Layers

An entirely Lagrangian similarity analysis is used to determine, (a) the mean trajectory and mean ground level concentration resulting from continuous sources located at the origin in both slightly unstable and strongly unstable boundary layers and (b) the behavior of particle pairs released near the ground in such layers. It is predicted that the mean particle trajectories are somewhat more sensitive to a slightly unstable condition than has been previously suggested and also that the mean ground level concentration drops off more rapidly with distance for a line source. Furthermore, the effective cloud diffusivity is linearly dependent on time for the neutral boundary layer and quadratically dependent on time in the strongly unstable limit.