Publication Date:
2010-10-01
Description:
Persistent organic pollutants (POPs) are recognized for their potential to create harmful effects in remote areas and several monitoring programs have been established which measure POPs in air. Active air sampling (AAS) has so far been the recommended method used under the EMEP (co-operative programme for monitoring and evaluation of the long-range transmissions of air pollutants in Europe) measurement program. The number of EMEP AAS stations is still limited and mainly located in the north western part of Europe. Passive air sampling (PAS) methods, which have become increasingly popular in recent years, offer an opportunity as a complementary sampling strategy which could improve sampling coverage under EMEP. To gain further insight into spatial patterns of POPs in European background air and to evaluate PAS as an alternative sampling technique under EMEP, PAS were deployed at 86 European background sites during summer 2006. Duplicate PAS samplers were also deployed at EMEP AAS sites to allow for a comparison of results obtained using both methods. The PAS were analyzed for selected PCBs, HCHs, DDTs, PAHs, chlordanes and HCB, and air concentrations were calculated on the basis of losses of performance reference compounds. Air concentrations of PCBs were generally lowest in more remote areas of Northern Europe with elevated levels in more densely populated areas. γ-HCH was found at elevated levels in more central parts of Europe, whereas α-HCH, β-HCH and DDTs showed higher concentrations in the southeastern part. There was no clear spatial pattern in the concentrations for PAHs, indicative of influence by local sources, rather than long range atmospheric transport (LRAT). HCB was evenly distributed across Europe, while the concentrations of chlordanes were typically low or non-detectable. Co-deployed PAS samples showed a fair agreement between the duplicates, typically within 30%. Larger differences were seen when comparing results obtained on the basis of AAS and PAS. The latter results illustrated that coordinated PAS campaigns have the potential serve as a useful intercomparison exercise within and across existing monitoring networks. We furthermore adopted an existing Lagrangian transport model (FLEXPART) as recently modified to incorporate key processes relevant for POPs to evaluate potential source regions affecting observed PAS concentrations at selected sites. Using PCB-28 as an example, the model predicted concentrations which agreed within a factor of 3 with PAS measurements for all except 2 out of the 17 sites that were investigated in this analysis.
Electronic ISSN:
1680-7375
Topics:
Geosciences
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