TY  - JOUR
AB  - Anthropogenic emissions are a dominant contributor to air pollution. 
      Consequently, mitigation policies have attempted to reduce anthropogenic
       pollution emissions in Europe since the 1990s. To evaluate the 
      effectiveness of these mitigation policies, the German Ultrafine Aerosol
       Network (GUAN) was established in 2008, focusing on black carbon and 
      sub-micrometer aerosol particles, especially ultrafine particles. In 
      this investigation, trends of the size-resolved particle number 
      concentrations (PNC) and the equivalent black carbon (eBC) mass 
      concentration over a 10-year period (2009–2018) were evaluated for 16 
      observational sites for different environments among GUAN. The trend 
      analysis was done for both, the full-length time series and on subsets 
      of the time series in order to test the reliability of the results. The 
      results show generally decreasing trends of both, the PNCs for all size 
      ranges as well as eBC mass concentrations in all environments, except 
      PNC in 10–30 nm at regional background and mountain sites. The annual 
      slope of the eBC mass concentration varies between −7.7 % and −1.8 % per
       year. The slopes of the PNCs varies from −6.3 % to 2.7 %, −7.0 % to 
      −2.0 %, and −9.5 % to −1.5 % per year (only significant trends) for 
      10–30 nm, 30–200 nm, and 200–800 nm particle diameter, respectively. The
       regional Mann-Kendall test yielded regional-scale trends of eBC mass 
      concentration, N[30–200] and N[200–800]
       of −3.8 %, −2.0 % and −2.4 %, respectively, indicating an overall 
      decreasing trend for eBC mass concentration and sub-micrometer PNC 
      (except N[10–30]) all over Germany. The most 
      significant decrease was observed on working days and during daytime in 
      urban areas, which implies a strong evidence of reduced anthropogenic 
      emissions. For the seasonal trends, stronger reductions were observed in
       winter. Possible reasons for this reduction can be the increased 
      average ambient temperatures and wind speed in winter, which resulted in
       less domestic heating and stronger dilution. In addition, decreased 
      precipitation in summer also diminishes the decrease of the PNCs and eBC
       mass concentration. For the period of interest, there were no 
      significant changes in long-range transport patterns. The most likely 
      factors for the observed decreasing trends are declining anthropogenic 
      emissions due to emission mitigation policies of the European Union.
AU  - Sun, J.*
AU  - Birmili, W.*
AU  - Tuch, T.*
AU  - Weinhold, K.*
AU  - Merkel, M.*
AU  - Rasch, F.*
AU  - Müller, T.*
AU  - Schladitz, A.*
AU  - Bastian, S.*
AU  - Löschau, G.*
AU  - Cyrys, J.
AU  - Gu, J.
AU  - Flentje, H.*
AU  - Briel, B.*
AU  - Asbach, C.*
AU  - Kaminski, H.*
AU  - Ries, L.*
AU  - Sohmer, R.*
AU  - Gerwig, H.*
AU  - Wirtz, K.*
AU  - Meinhardt, F.*
AU  - Schwerin, A.*
AU  - Bath, O.*
AU  - Ma, N.*
AU  - Wiedensohler, A.*
C1  - 57412
C2  - 47751
TI  - Decreasing trends particle number and black carbon mass concentrations at 16 observational sites in Germany  from 2009 to 2018.
JO  - Atmos. Chem. Phys. Discus.
PY  - 2019
SN  - 1680-7367
ER  - 

TY  - JOUR
AB  - Trees can significantly impact the urban air chemistry by the uptake and emission of reactive biogenic volatile organic compounds (BVOCs), which are involved in ozone and particle formation. Here we present the emission potentials of "constitutive" (cBVOCs) and "stress-induced" BVOCs (sBVOCs) from the dominant broadleaf woody plant species in the megacity of Beijing. Based on an inventory of BVOC emissions and the tree census, we assessed the potential impact of BVOCs on secondary particulate matter formation in 2005 and 2010, i.e., before and after realizing the large tree-planting program for the 2008 Olympic Games. We found that sBVOCs, such as fatty acid derivatives, benzenoids and sesquiterpenes, constituted a significant fraction (∼ 15 %) of the total annual BVOC emissions, and we estimated that the overall annual BVOC budget may have doubled from ∼ 3.6 × 109 g C year-1 in 2005 to ∼ 7.1 × 109 g C year-1 in 2010 due to the increase in urban greens, while at the same time, the emission of anthropogenic VOCs (AVOCs) could be lowered by 24 %. Based on our BVOC emission assessment, we estimated the biological impact on SOA mass formation in Beijing. Compared to AVOCs, the contribution of biogenic precursors (2–5 %) for secondary particulate matter in Beijing was low. However, sBVOCs can significantly contribute (∼ 40 %) to the formation of total secondary organic aerosol (SOA) from biogenic sources; apparently, their annual emission increased from 1.05 μg m-3 in 2005 to 2.05 μg m-3 in 2010. This study demonstrates that biogenic and, in particular, sBVOC emissions contribute to SOA formation in megacities. However, the main problems regarding air quality in Beijing still originate from anthropogenic activities. Nevertheless, the present survey suggests that in urban plantation programs, the selection of plant species with low cBVOC and sBVOC emission potentials have some possible beneficial effects on urban air quality.
AU  - Ghirardo, A.
AU  - Xie, J.*
AU  - Zheng, X.*
AU  - Wang, Y.*
AU  - Grote, R.*
AU  - Block, K.
AU  - Wildt, J.*
AU  - Mentel, T.*
AU  - Kiendler-Scharr, A.*
AU  - Hallquist, M.*
AU  - Butterbach-Bahl, K.*
AU  - Schnitzler, J.-P.
C1  - 46915
C2  - 39030
SP  - 23005-23049
TI  - Urban stress-induced biogenic VOC emissions impact secondary aerosol formation in Beijing.
JO  - Atmos. Chem. Phys. Discus.
VL  - 15
PY  - 2015
SN  - 1680-7367
ER  - 

TY  - JOUR
AB  - From the rural Global Atmosphere Watch (GAW) site Hohenpeissenberg in the pre-alpine area of Southern Germany, a dataset of 24 C2–C8 non-methane hydrocarbons over a period of seven years was analyzed. Receptor modeling was performed by Positive Matrix Factorization (PMF) and the resulting factors were compared to literature source profiles. Photochemical aging during transport to the relatively remote site violates the PMF prerequisite of mass conservation from source to receptor. However, previous studies showed plausible results with this method at remote sites; the applicability and restrictions of the PMF model to such a remote dataset and the influence of photochemical processing on the interpretability of the results are discussed. A six factor solution showed a high stability and the most plausible results. In addition to biogenic sources and remote sources of very stable compounds – reflecting the continental background – four additional anthropogenic factors were resolved that could be divided into two short- and two long-lived patterns from evaporative sources and incomplete combustion processes, respectively. A method to increase the uncertainty for each individual compound by including photochemical reactivity did not improve the results, but decreased the stability of the model output. The contribution of the different source categories at the site over the entire period was, in decreasing order: remote sources, long-lived evaporative sources, residential heating and long-lived combustion sources, short-lived evaporative sources, short-lived combustion sources, and biogenic sources. Despite a low overall impact, biogenic sources played an important role during summer, in particular in terms of reactivity.
AU  - Leuchner, M.*
AU  - Gubo, S.*
AU  - Schunk, C.*
AU  - Wastl, C.*
AU  - Kirchner, M.
AU  - Menzel, A.*
AU  - Plass-Dülmer, C.*
C1  - 32404
C2  - 35069
CY  - Göttingen
SP  - 8143-8183
TI  - Can positive matrix factorization identify sources of organic trace gases at the continental GAW site Hohenpeissenberg?
JO  - Atmos. Chem. Phys. Discus.
VL  - 14
PB  - Copernicus Publ.
PY  - 2014
SN  - 1680-7367
ER  -