1. Temporal trend of background atmospheric PAH concentration in France derived from archived leaves
Emmanuel NAFFRECHOUX
LCME, University Savoie Mont-Blanc, France
NEGRO Sara , CARTERET Marion, BESSE-DELEAVAL Julie, DAVID Bernard (LCME)
POULENARD Jerome (EDYTEM, CNRS University Savoie Mont-Blanc)
NICOLAS Manuel (RENECOFOR, ONF Fontainebleau)

2. Regulation of PAHs emission in Europe: a success for air quality ?
Numerous industrialized states attempt to reduce harmful pollutants concentration in the air making legislation (european directive  96/62/CE, 2008/50/CE, French décret n° )
→ is it successful ?
Between 1990 and 2011, total PAH emissions decreased in the EU-27 by 58 %.
The Member States that contributed most (more than 10 %) to the emissions of total PAHs in 2011 were Spain, Germany, Poland and Romania.

3. → Quite a poor time resolution !
Conclusion from indirect measurements (ice or sediment cores) ?
J Gabrieli, Environ. Sci. Technol. 2010
E. Leorri, Science of the Total Environment, 2014
→ Quite a poor time resolution !
Some conclusions could be drawn from indirect measurements, from ice cores or sediment cores.

4. proximity to primary sources drives PAH air concentrations
Inference from direct measurements of PAHs concentration in air (gas+particle)?
K. Prevedouros, Environmental Pollution 2004
The best way to quantify the efficiency of legislation will be to measure directly the pollutant concentration in the air.
However, the inherent noise in ambient air monitoring data makes it difficult to derive unambiguous evidence of underlying declines.
It is quite impossible to confirm the effectiveness of international source reduction measures.
proximity to primary sources drives PAH air concentrations
strong winter>summer seasonality is linked to seasonally-dependent sources
downward trend for many PAHs at some sites… but increasing trends at Hazelrigg for Fla, Py and B[a]A

5. → difficult to derive unambiguous evidence of declines
Use of data from long-term air monitoring projects (IADN and EMEP): 4 HMW PAHs
L.Y. Liu, Environment International 2014
→ difficult to derive unambiguous evidence of declines
Significant long-term decreasing trends of all these PAH atmospheric concentrations were observed at Chicago and Cleveland.
For the other sites, either less significant or no long-term decreasing trends were observed.
Clear seasonality was observed at Košetice and Aspvreten (the same at Sleeping Bear Dunes) with the highest PAH concentrations observed in mid-January.

6. Inter- and intraspecific variations around a factor 3
No information on the seasonal variability of the air concentrations
Usefull for assessment of temporal trends (to discern variations of an order of magnitude)

7. C. Schröter-Kermani, J. Environ. Monit., 2006
No clear tendancy in rural sites
C. Schröter-Kermani, J. Environ. Monit., 2006

8. RENECOFOR (Réseau National de suivi à long terme des ECOsystèmes FORestiers)
Created by ONF in 1992
Long term monitoring of forest ecosystems and understanding of modifications
14 sampling forest plots
All remote sites
10 with coniferous trees
4 with deciduous trees
8-9 months old vegetal

10. No clear relationship between variables
→ sampling sites can be considered as receptors of LRAT PAHs
Predominance of LMW PAHs
PHE(50%)>FLT>PYR>FLN
Phenanthrene, fluoranthene, pyrene and fluorene (in that order) are the most abundant compounds in the vegetation.

11. atmospheric signature ≈ emission signature
A. Dvorská, Atmospheric Environment 2012
atmospheric signature ≈ emission signature
comparable profile in 1990’ and 2000’
Predominance of LMW PAHs
PHE>FLN>FLA>PYR
PHE ≈ 25 to 60% tot
S.N. Meijer, Environ. Sci. Technol. 2008
The “vegetals” signature is comparable to the atmospheric signature.
This last one seems to closely mirror emissions, which have quite the same profile since 1990.
It is possible to conclude that levels of PAHs in air are still influenced by the same sources…
or more probably this lends strength to the idea that source apportionment is very limited with these PAH.
Anyway, the PAH signature in our leaves or needles seems related to PAH air composition.

12. B.L. Van Drooge, Environ. Sci. Pollut. Res. 2010

13. Simulated concentration : 5 ngPHE/g in 2030

14. From vegetation to atmospheric concentration
J. Klanova, Envir. Poll., 2009 →Veq(m3/g)=CV/CA
For PHE, Veq=9-18 m3/g and CV=30 ng/g in → CA=1.7 to 3.3 ng/m3
Tentative air concentration in 2030: [PHE]=0.3 to 0.6 ng/m3

15. Some ideas to bring back home
1) about PAHs contamination of the air in France:
global diminution (comparable trend in UK)
Actual [PHE]≈1 ng/m3
[PHE]<0.3ng/m3 probably after 2030 !
specific variations due to sources influence (forest fire, urban area)
2) How to (well) use leaves as PAH passive samplers for air quality evaluation:
numerous tree species
«old» leaves or needles (8 to 9 months old)
numerous sampling sites (>10)
distant from ponctual sources (>50 km)
quantification of LMW PAHs (or PHE)
need of more experiments to convert vegetal to atmospheric concentration

16. Thank your for your attention...
see you in the french alpine forests !
blackpeuf.com