An 11 year study of multipollutant correlations of urban aerosols in Krakow, Poland

Krakow is the most polluted, as far as particulate matter (PM) is concerned, city in Poland. This is an important public concern as Krakow is also the second largest populated Polish city. The specific geomorphological localization of Krakow influences the atmospheric dynamics over the city, resulting in still- or weak-winds promoting air pollution accumulation, especially during the heating season. Seasonal variability in concentrations and multipollutant correlations of gaseous pollutants (i.e. NO2, NO, NOx, SO2) and PM10, 2.5 measured over a period of January 2005 to December 2013 were investigated. Data for the study were obtained from reports published by the Voivodship Inspectorate for Environmental Protection in Krakow. A strong seasonal variation in PM10 concentration revealed that during warm months the European Union annual limit value of 40 µg/m3 was not exceeded, whereas during the heating season, it was exceeded more than twice (Figure 1). Normalized monthly concentration patterns of all investigated pollutants and temperatures revealed that NO2 had the most consistent concentration pattern over the year. Conversely, SO2, PM2.5 and PM10 levels varied greatly (e.g. SO2 concentrations in January were more than 100% greater and 54% lower than the monthly average in May). Moreover SO2 had the strongest negative correlation (r = -0.64) with temperature. Seasonal correlations between pairs of pollutants were the highest between NO and NOx (0.99) and between PM10 and PM2.5 in annual and seasonal terms. The non-heating season (May-August) was characterised by lower coefficients than the heating season (September-April), when coefficients were similar to the annual values. Additionally, the ratios between average concentrations of investigated pollutants were also higher in the heating season. Transmission electron microscopy (TEM) images confirmed that particles were consistent with the known morphology of fly-ash (Brown et al., 2011) and other combustion-derived PM (BéruBé et al., 1999; Figure 2). For example, individual carbonaceous spheres’ forming grape-like bunches of aggregates and agglomerates which are highly-respirable. Natural factors such as geomorphology, climate and weather conditions have been determined to be the perpetrators of air pollution accumulation over the city (Wlodarczyk et al., 2015). The main source of elevated pollution levels were traffic emissions (i.e. nitrogen compounds) during warm months and residential coal-burning during the heating season. In conclusion, high annual levels, especially for PM, are greatly affected by measurements from the heating season. This ‘seasonality’ in PM2.5 concentrations should be taken into account when treating PM2.5 as a proxy in epidemiological studies for Krakow; as people in colder months spend less time outdoors. Further analysis including in vitro toxicology of PM is required to assess its direct effects on human lung biology. Brown, P., Jones, T. and BéruBé, K. (2011). Environmental Pollution 159 (12):3324-3333. BéruBé, K., Williamson, B., Winters, C., et al., (1999). Atmospheric Environment, 33(10):1599-1614

Source apportionment and the role of meteorological conditions in the assessment of air pollution exposure due to urban emissions

As particulate matter (PM) impacts human health, knowledge about its composition, exposure and source apportionment is required. A study of the urban atmosphere in the case of Augsburg, Germany, during winter (31 January–12 March 2010) is thus presented here. Investigations were performed on the basis of aerosol mass spectrometry and further air pollutants and meteorological measurements, including mixing layer height. Organic matter was separated by source apportionment of PM1 with positive matrix factorization (PMF) in three factors: OOA – oxygenated organic aerosol (secondary organic factor), HOA – hydrocarbon-like organic aerosol (traffic factor or primary organic factor) and WCOA – wood combustion organic aerosol (wood combustion factor), which extend the information from black carbon (BC) measurements. PMF was also applied to the particle size distribution (PSD) data of PM2.5 to determine different source profiles and we assigned them to the particle sources: nucleation aerosol, fresh traffic aerosol, aged traffic aerosol, stationary combustion aerosol and secondary aerosol. Ten different temporal phases were identified on the basis of weather characteristics and aerosol composition and used for correlations of all air pollutants and meteorological parameters. While source apportionment from both organic PM composition and PSD agree and show that the main emission sources of PM exposure are road traffic as well as stationary and wood combustion, secondary aerosol factor concentrations are very often the highest ones. The hierarchical clustering analysis with the Ward method of cross-correlations of each air pollutant and PM component and of the correlations of each pollutant with all meteorological parameters provided two clusters: "secondary pollutants of PM1 and fine particles" and "primary pollutants (including CO and benzene) and accumulation mode particles". The dominant meteorological influences on pollutant concentrations are wind speed and mixing layer height which are coupled with a certain wind direction. The compounds of the cluster "secondary pollutants and fine particles" show a negative correlation with absolute humidity, i.e., low concentrations during high absolute humidity and vice versa. The PM10 limit value exceedances originated not only from the emissions but also in combination with specific meteorological conditions. NC3-10 (number concentration of nucleation mode particles) and NC10-30 (Aitken mode particles), i.e., ultrafine particles and the fresh traffic aerosol, are only weakly dependent on meteorological parameters and thus are driven by emissions. The results of this case study provide information about chemical composition and causes of PM exposure during winter time in urban air pollution

Particulate matter from both heavy fuel oil and diesel fuel shipping emissions show strong biological effects on human lung cells at realistic and comparable in vitro exposure conditions

Background: Ship engine emissions are important with regard to lung and cardiovascular diseases especially in coastal regions worldwide. Known cellular responses to combustion particles include oxidative stress and inflammatory signalling. Objectives: To provide a molecular link between the chemical and physical characteristics of ship emission particles and the cellular responses they elicit and to identify potentially harmful fractions in shipping emission aerosols. Methods: Through an air-liquid interface exposure system, we exposed human lung cells under realistic in vitro conditions to exhaust fumes from a ship engine running on either common heavy fuel oil (HFO) or cleaner-burning diesel fuel (DF). Advanced chemical analyses of the exhaust aerosols were combined with transcriptional, proteomic and metabolomic profiling including isotope labelling methods to characterise the lung cell responses. Results: The HFO emissions contained high concentrations of toxic compounds such as metals and polycyclic aromatic hydrocarbon, and were higher in particle mass. These compounds were lower in DF emissions, which in turn had higher concentrations of elemental carbon (“soot”). Common cellular reactions included cellular stress responses and endocytosis. Reactions to HFO emissions were dominated by oxidative stress and inflammatory responses, whereas DF emissions induced generally a broader biological response than HFO emissions and affected essential cellular pathways such as energy metabolism, protein synthesis, and chromatin modification. Conclusions: Despite a lower content of known toxic compounds, combustion particles from the clean shipping fuel DF influenced several essential pathways of lung cell metabolism more strongly than particles from the unrefined fuel HFO. This might be attributable to a higher soot content in DF. Thus the role of diesel soot, which is a known carcinogen in acute air pollution-induced health effects should be further investigated. For the use of HFO and DF we recommend a reduction of carbonaceous soot in the ship emissions by implementation of filtration devices

Image processing of affymetrix microarrays.

One of the purposes of several statistical techniques is to reduce random noise and improve the quality of the data. In microarray experiments random noise can introduce errors that affect gene expression measurements and obscure the interesting biological variation. In recent years, several authors have described common techniques to minimize the effects of systematic variation incorporated into microarray data at different stages of the manufacturing process (see for example [3] and [4]). There is though a particular step in the microarray data analysis workflow that is and that be performed the image of raw data

BZLF1 governs CpG-methylated chromatin of Epstein-Barr virus reversing epigenetic repression.

Epigenetic mechanisms are essential for the regulation of all genes in mammalian cells but transcriptional repression including DNA methylation are also major epigenetic mechanisms of defense inactivating potentially harmful pathogens. Epstein-Barr Virus (EBV), however, has evolved to take advantage of CpG methylated DNA to regulate its own biphasic life cycle. We show here that latent EBV DNA has an extreme composition of methylated CpG dinucleotides with a bimodal distribution of unmethylated or fully methylated DNA at active latent genes or completely repressed lytic promoters, respectively. We find this scenario confirmed in primary EBV-infected memory B cells in vivo. Extensive CpG methylation of EBV's DNA argues for a very restricted gene expression during latency. Above-average nucleosomal occupancy, repressive histone marks, and Polycomb-mediated epigenetic silencing further shield early lytic promoters from activation during latency. The very tight repression of viral lytic genes must be overcome when latent EBV enters its lytic phase and supports de novo virus synthesis in infected cells. The EBV-encoded and AP-1 related transcription factor BZLF1 overturns latency and initiates virus synthesis in latently infected cells. Paradoxically, BZLF1 preferentially binds to CpG-methylated motifs in key viral promoters for their activation. Upon BZLF1 binding, we find nucleosomes removed, Polycomb repression lost, and RNA polymerase II recruited to the activated early promoters promoting efficient lytic viral gene expression. Surprisingly, DNA methylation is maintained throughout this phase of viral reactivation and is no hindrance to active transcription of extensively CpG methylated viral genes as thought previously. Thus, we identify BZLF1 as a pioneer factor that reverses epigenetic silencing of viral DNA to allow escape from latency and report on a new paradigm of gene regulation

Open chromatin structures regulate the efficiencies of pre-RC formation and replication initiation in Epstein-Barr virus.

Whether or not metazoan replication initiates at random or specific but flexible sites is an unsolved question. The lack of sequence specificity in origin recognition complex (ORC) DNA binding complicates genome-scale chromatin immunoprecipitation (ChIP)-based studies. Epstein-Barr virus (EBV) persists as chromatinized minichromosomes that are replicated by the host replication machinery. We used EBV to investigate the link between zones of pre-replication complex (pre-RC) assembly, replication initiation, and micrococcal nuclease (MNase) sensitivity at different cell cycle stages in a genome-wide fashion. The dyad symmetry element (DS) of EBV's latent origin, a well-established and very efficient pre-RC assembly region, served as an internal control. We identified 64 pre-RC zones that correlate spatially with 57 short nascent strand (SNS) zones. MNase experiments revealed that pre-RC and SNS zones were linked to regions of increased MNase sensitivity, which is a marker of origin strength. Interestingly, although spatially correlated, pre-RC and SNS zones were characterized by different features. We propose that pre-RCs are formed at flexible but distinct sites, from which only a few are activated per single genome and cell cycle

Spatial and temporal variability of source contributions to ambient PM10 during winter in Augsburg, Germany using organic and inorganic tracers.

Daily PM10 samples were collected during a one-month sampling campaign from February 13 to March 12, 2008 at eight different sampling sites in Augsburg, Southern Germany. Source apportionment was performed to identify the main sources and related contributions by analysis of organic and inorganic tracers. Nine factors were separated comprising: solid fuel combustion, traffic-related emissions, secondary inorganics, and mixed sources. Spatiotemporal variation of the source contributions was evaluated using the Pearson correlation coefficient (r) and coefficient of divergence (COD). All factors (except hopanes and mixed sources) showed moderate to high (0.60.8) correlation coefficients between the eight sites and were distributed heterogeneously. Secondary sulfate and secondary nitrate factors were relatively more uniformly distributed (compared to other factors) with lower medians of COD value (0.47 and 0.56, respectively) and higher correlation values (r=0.97 and 0.85, respectively). The maximum daily average contribution for coal & wood combustion factor was observed at the LfU suburban site (4.0μgm(-3)); wood combustion factor at the LSW residential site (5.1μgm(-3)) ; diesel & fuel oil consumption factor at the Bifa suburban and BP urban sites (both 2.5μgm(-3)); road dust & tram factor at the KP traffic site (16.2μgm(-3)) and the BP urban site (6.6μgm(-3)); hopanes factor at the BP urban and Bifa suburban sites (both 0.7μgm(-3)); and de-icing NaCl factor at the KP traffic site (4.8μgm(-3)). Secondary sulfate and secondary nitrate factors had approximately similar contributions (6.2μgm(-3) and 4.3μgm(-3), respectively) at all sites. Mixed sources factor had the highest daily average contribution to PM10 mass at the KP traffic site (7.0μgm(-3))

Comparison of emissions from wood combustion. Part 2: Impact of combustion conditions on emission factors and characteristics of particle-bound organic species and Polycyclic Aromatic Hydrocarbon (PAH)-related toxicological potential.

The impact of combustion conditions on emission factors and characteristics of log wood combustion was investigated. Two different kinds of log woods (spruce and beech) and one kind of briquette (spruce sawdust) were used to study differences in emission behavior depending upon the wood type. Beech wood was used to examine additionally the impact of different moisture contents and maloperation on emissions of fine particulate matter (PM). Therefore, wood logs with three different levels of moisture content were used. Maloperation was simulated by an overload scenario and an air deficiency scenario. Toxicity equivalent (TEQ) values were calculated for the different combustion conditions. It was found that PM mass varies only by a factor of 8 at a maximum, whereas TEQ values can vary more than a factor of 80 (regular beech wood combustion, 6 μg MJ–1; beech wood combustion in an overloaded combustion chamber, 500 μg MJ–1). In particular, wood with a higher moisture content (19%) released high amounts of intermediate products from lignin and cellulose degradation. The PM emissions in this case were the highest among the tested operation conditions, especially during the initial (cold start) inflaming (660 μg MJ–1), but were not in correspondence with the toxicity potential. The TEQ (37 μg MJ–1) in that case was much lower than during maloperation

An evaluation of the "GGP" personal samplers under semi-volatile aerosols: Sampling losses and their implication on occupational risk assessment.

Semi-Volatile (SV) aerosols still represent an important challenge to industrial hygienists due to toxicological and sampling issues. Particularly problematic is the sampling of hazardous SV that are present in both particulate and vapour phases at a workplace. In this study we investigate the potential evaporation losses of SV aerosols when using off-line filter-adsorber personal samplers. Furthermore, we provide experimental data showing the extent of the evaporation loss that can bias the workplace risk assessment. An experimental apparatus consisting of an aerosol generator, a flow tube and an aerosol monitoring and sampling system was set up inside a temperature controlled chamber. Aerosols from three n-alkanes were generated, diluted with nitrogen and sampled using on-line and off-line filter-adsorber methods. Parallel measurements using the on-line and off-line methods were conducted to quantify the bias induced by filter sampling. Additionally, two mineral oils of different volatility were spiked on filters and monitored for evaporation depending on the samplers flow rate. No significant differences between the on-line and off-line methods were detected for the sum of particles and vapour. The filter-adsorber method however tended to underestimate up to 100 % of the particle mass, especially for the more volatile compounds and lower concentrations. The off-line sampling method systematically returned lower particle and higher vapour values, an indication for particle evaporation losses. We conclude that using only filter sampling for the assessment of semi-volatiles may considerably underestimate the presence of the particulate phase due to evaporation. Thus, this underestimation can have a negative impact on the occupational risk assessment if the evaporated particle mass is no longer quantified

Short-term evaporation of semi-volatile N-alkane aerosol particles: Experimental and computational approach.

The process of semi-volatile aerosol particle evaporation was studied with respect to both computational and experimental approaches. A Sinclair-La Mer type aerosol generator was used to produce monodisperse particles from four n-alkanes (tetradecane, hexadecane, octadecane, eicosane) while particle sizing and FID measurements were applied to quantify particle- and vapor mass and their subsequent phase distribution. Aerosol dilution and later stationary analyses in a flow tube at two time intervals enabled an experimental study on particle evaporation into a finite and constant volume. Experiments carried out for n-alkanes at 25 degrees C showed that tetradecane particles evaporated almost completely within 3 seconds whereas eicosane particles remained nearly unchanged. A diffusion based model that accounts for the evaporation dynamic of variously concentrated particle populations was developed. Good agreement between experimental and computational results was found, with relative deviations being less than 20% for the majority of the experiments. The study has shown that evaporation of semi-volatile n-alkane aerosol particles can be successfully predicted using the diffusion based model