Atmospheric sulfur and nitrogen budgets for southeast Europe

Precipitation composition and wet deposition temporal pattern in Central Serbia for the period from 1998 to 2004

Bulk samples collected on a daily basis at three principal meteorological stations in central Serbia were analyzed on chloride (Cl(-)), nitrate (NO(3)(-)), sulfate (SO(4)(2-)), sodium (Na(+)), ammonium (NH(4)(+)), potassium (K(+)), calcium (Ca(2+)), and magnesium (Mg(2+)) in addition to precipitation amount, pH and conductivity measurements over the period 1998-2004. The data were subjected to variety of analyses (linear regression, principal component analysis, time series analysis) to characterize precipitation chemistry in the study area. The most abundant ion was SO(2-)(4) with annual volume weighted mean concentration of 242 microeq L(-1). Neutralization of precipitation acidity occurs both as a result of the dissolution of alkaline compounds containing Ca(2+), Mg(2+), and K(+) as well as the absorption of ammonia. The ratio of SO(4)(2-)/NO(3)(-) was above 5, which indicated that the combustion process of low-grade domestic lignite for electricity generation from coal-fired thermal power plants was the main source of pollution in the investigated area. A considerable mean annual bulk wet deposition of SO(4)-S determined by precipitation amount and concentrations of sulfate in the precipitation was calculated to be 12-35 kg ha(-1).

Atmospheric sulfur flux rates to and from Israel

Both field measurements and model simulation studies have shown that Israel is the recipient of long range transported air pollutants that originated over various parts of Europe. The present paper presents results of aircraft measurements aimed at quantitizing the sulfur flux arriving at Israel's western coast from Europe and the Israeli pollution contribution to the air masses leaving its eastern borders towards Jordan. During the research flights, measurements of sulfur dioxide and sulfate particulates and meteorological data were recorded. Two different legs were performed for each research flight: one over the Mediterranean Sea, west of the coast and the second along the Jordan Valley. All flights were carried out at a height of approximately 300 m above ground level. A total of 14 research flights were performed covering the summer and autumn seasons. The results indicate that the influx of sulfur arriving at the Israeli coast from Europe varied in the range of 1-30 mg S/h, depending on the measuring season. The particulate sulfate level in the incoming LRT air masses was at least 50% of the total sulfur content. The contribution of the local pollutant sources to the outgoing easterly fluxes also varies strongly according to season. During the early and late summer, the Israeli sources contributed an average of 25 mg S/h to the total pollution flux as compared to only approximately 9 mg S/h during the autumn period. Synoptic analysis indicates that conditions during the summer in Israel favor the accumulation of pollution species above the Mediterranean basin from upwind European sources. This season features a shallow mixed layer and weak zonal flow leads to poor ventilation rates, inhibiting an efficient dispersion of these pollutants while being transported eastward. Under these conditions, in flux, local contribution and the total out-flux of these pollutants are elevated as opposed to during other seasons. During the fall, the eastern Mediterranean region is usually subjected to weak easterly winds, interrupted at times by strong westerly wind flows inducing higher ventilation rates. These meteorological conditions and the lack of major emitting sources eastwards of Israel result in lower sulfur budgets to and from Israel for this season. An estimate of the yearly flux showed that approximately 0.06 tg S arrived at the Israeli coast from the west. This is approximately 15% of the estimated pollution leaving Europe towards the eastern edge of the Mediterranean basin. The local contribution to the out-flux towards Jordan was calculated to be 0.13 tg S per year, almost all of the sulfur air pollutants emitted in Israel.

The potential for long-range transport of air-pollutants into Greece: a climatological analysis

A flow climatology using 5 years (1983-1987) of back trajectories has been created for the Aliartos meteorological-chemical station (Greece's EMEP-station phi = 38 degrees 13'N, lambda = 23 degrees 00'E) using the Air Resources Laboratory (ARL) trajectory model. Air mass back trajectories were analysed to quantify the contributions of major source areas to the air pollution concentration in the area of Greece. The trajectories were produced two times a day at the 850-hPa and 700-hPa pressure surface. The trajectories were classified and summarised in order to produce a long range trajectory climatology. The purpose of this paper is to use the above flow climatology to improve understanding to atmospheric transport pathways to Greece (and to the greater south-eastern area of Europe) and to evaluate the polluting potential of distant source regions outside the country. The limited chemical concentration data available from Aliartos are used to evaluate the conclusions reached from the flow climatology and emissions analysis. The results show that trajectories reach Greece from five major source areas: (i) Northwest Europe, (ii) west Europe, (iii) north Europe, (iv) Northwest Asia, and (v) Northwest Africa. Sector analysis of air pollution concentrations and emissions also showed that: (i) Most air pollutants transport from distances beyond 1800 km takes place, and the most probable source areas are the industrialised countries of Europe. (ii) Countries of west and north-central Europe emit the greater amounts of air pollutants (S and N). (iii) Sulphate and nitrate concentrations are similar among transport sectors.