Regional air quality in Leipzig, Germany: detailed source apportionment of size-resolved aerosol particles and comparison with the year 2000

A detailed source apportionment of size-resolved aerosol particles in the area of Leipzig, Germany, was performed. Sampling took place at four sites (traffic, traffic/residential, urban background, regional background) in parallel during summer 2013 and the winters 2013/14/15. Twenty-one samples were taken per season with a 5-stage Berner impactor and analysed for particulate mass, inorganic ions, organic and elemental carbon, water-soluble organic carbon, trace metals, and a wide range of organic species. The compositional data were used to estimate source contributions to particulate matter (PM) in quasi-ultrafine (up to 140 nm), accumulation mode, and coarse size ranges using Positive Matrix Factorisation (PMF) receptor modelling. Traffic (exhaust and general traffic emissions), coal combustion, biomass combustion, photochemistry, general secondary formation, cooking, fungal spores, urban dust, fresh sea/road salt, and aged sea salt were all found to contribute to different extents to observed PM concentrations. PMF derived estimates agreed reasonably with estimates from established macrotracer approaches. Quasi-ultrafine PM originated mainly from traffic (20–50%) and photochemistry (30–50%) in summer, while it was dominated by solid fuel (mainly biomass) combustion in winter (50–70%). Tentatively identified cooking aerosol contributed up to 36% on average at the residential site. For accumulation mode particles, two secondary sources typically contributed 40–90% to particle mass. In winter, biomass and coal combustion contributions were up to ca. 25% and 45%, respectively. Main sources of coarse particles were diverse and included nearly all PMF-resolved ones depending on season and air mass origin. For PM₁₀, traffic (typically 20–40% at kerbside sites), secondary formation (30–60%), biomass combustion (10–15% in winter), and coal combustion (30–40% in winter with eastern air mass inflow) were the main quantified sources. At the residential site, contributions from biomass combustion derived up to 60% from local emissions. Coal combustion as a significant source was only present during eastern air mass inflow and showed very similar concentrations at all sites, indicating the importance of trans-boundary air pollution transport in the study area. Overall, nearly half of the PM₁₀ mass was attributed to urban sources by a simple subtractive approach with highest reduction potentials of up to 80% for local (urban) mitigation measures in ultrafine and coarse particles. Local increments of elemental carbon have decreased by about 50% as compared to the year 2000, corroborating results from a former study on the positive effects of a low emission zone, implemented in Leipzig in 2011.

Main particulate matter components in Saxony (Germany): Trends and sampling aspects

Aerosol filter samples have been collected nearby the industrialised basin of Leipzig in Saxony (Germany) at the research station Melpitz of the Institut für Troposphärenforschung e.V. (IfT). Time series (1992-1998) and a three year comparison (1995-1997) of two different aerosol filter sampling systems, the Sierra-Andersen-PM 10 high volume sampler (daily sample, PM 10 inlet) and the Rupprecht and Patashnik Co. Inc. Model Partisol 2000 (weekly sample, PM 10 and PM 2.5 inlet) are presented and discussed. The comparison of the different sampling systems and strategies yields small differences between the daily and weekly samples for mass and different ions, which may be influenced by sampling duration and flow rates. A general trend of change in aerosol composition was observed: Soot and Sulphate concentrations decreased whereas Nitrate and Ammonium concentrations increased. During summers the mass of coarse particles is higher than in other seasons. One reason could be found in the occurrence of longer periods of dry ground surfaces enabling reemission of crustal and biological material. The time series have been integrated in a longer historical aerosol mass trend for Saxony and do show a good agreement. Since 1990 a significant downward trend in gravimetric mass concentration was found.

Long-term expression of the hepatitis B virus core-e- and X-proteins does not cause pathologic changes in transgenic mice

BACKGROUND/AIMS

Chronic infections with the human hepatitis B virus can result in liver cirrhosis and primary hepatocellular carcinoma. The reasons for these long-term effects are unclear. The aim of this study was to generate transgenic mice expressing the HBV X- and c/e-gene under authentic and foreign promoter control and to test whether the respective gene products can cause pathologic effects during the lifespan of a mouse. Moreover, the temporal and the tissue-specific regulation of the crucial HBV c/e-gene promoter was analyzed.

METHODS

Eight transgenic mouse lines were generated. Four contained the c/e- and X-gene and two contained only the X-gene under authentic promoter control. Two lines expressed only the X-gene under control of the rat insulin promoter/enhancer. Gene expression was tested by protein and mRNA analyses. During an observation period of 2 years, mice were sacrificed and organs subjected to histologic examination. Mice expressing the X-gene in pancreatic beta cells were tested for the development of diabetes.

RESULTS

In the liver, slight histopathologic alterations but no neoplastic changes could be observed in mice expressing the X-gene. Activity of the c/e-gene promoter/enhancer was age dependent and was not restricted to hepatocytes.

CONCLUSION

No evidence was obtained that long-term expression of the HBV c/e- and X-gene products can cause neoplasia during the lifespan of a mouse.