Ambient air
air masses (taken from Bartoš 2003)
As ambient air pollution and its impact on human health have become a subject of broad public interest, new methods for air sampling and subsequent determination of various chemical substances present in air have recently been developed. A high attention is paid especially to persistent organic pollutants (POPs) due to their extensive distribution, ability of bioaccumulation in fat tissues, cancerogenity, mutagenicity and possible endocrine disruption. They are emitted into ambient air from various primary and secondary sources and atmosphere plays a key role in their transport both around their source surroundings and on long distances. Atmospherical transport is also main pathway of POPs transport into aquatic and terrestric ecosystems (Hermanson et al., 1991; Harner et al., 1995). Current research of POPs global fate searches new information on sources (Hafner and Hites, 2003), but also on other factors that affect pollutants concentration in ambient air, because climate (Simcik et al., 1999; Ma et al., 2004), processes at the interface of air and soil or water surface, and atmospherical transport significantly affect spatial and time variability of POPs in ambient air (Hillery et al., 1997; Cousins and Jones, 1998; Bidleman, 1999). From this point of view, regular measurements of pollutants concentration in ambient air at various localities and monitoring studies at various levels from immediate vicinity of local point sources up to continental level are of key importance. Important components of these measurements are monitoring design, selection of monitored chemicals, selection of sampling and analytical methods, processing method, and data interpretation.
Issues of POPs in atmosphere have currently been a subject of several international regional and global conventions, of which the Stockholm Convention on Persisten Organic Pollutants (SC) is of highest significance from global point of view. One of the SC member countries is also the Czech Republic (Holoubek et al., 2005). The main aim of the SC is protection of human health and the environment from POPs by means of their emissions reduction and elimination.
It is naturally important to evaluate whether and how the SC aims are achieved. Therefore, a mechanism must exist that provides all signatory countries authentic, representative, and comparable monitoring data about background levels of these substances at localities that are not directly affected by local sources and their trends. Efficiency evaluation of accepted measures must be an integral part of National Implementation Plans (NIP). This approach is also embeded in the Czech NIP.
Nowadays there is a number of regional monitoring programmes that provide data on POPs occurrence in the environment. Nevertheless, there is almost no experience with POPs monitoring proposal so that it could serve for efficiency evaluation of obligations and measures resulting from international conventions on a global level.
According to the Paragraph 16 the Convention efficiency evaluation started four years after it entered into force and subsequently in 6-year intervals. Persistent pollutants global monitoring that is supposed to become a tool for such evaluation and ensure even coverage of all regions must be feasible and sustainable, thus simple, practical, and cheap. It is necessary to be based upon existing programmes and use available data and capacities in a maximal possible extent.
The SC Technical Group (founded at the 2nd Conference of the Parties) suggested ambient air and breast milk as suitable matrices for POPs global monitoring. This concept was accredited at the 3rd Conference of the Parties in 2007 together with the plan of global monitoring implementation and methodological procedure for its realization.
Regarding ambient air, two approaches are being considered: active sampling employing so called high-volume samplers, which would be used in range of 3-5 so called superstations per UN region, and so called passive sampling using polyurethane foam or polymer sorbent Amberlite XAD-2 in range of 15-20 backgroung localities per region.
high-volume sampler PS-1
1) Active sampling in the Czech Republic
The Czech Republic is one of the few European countries, in which a long-term monitoring of POPs has existed. Due to the cooperation of RECETOX MU and CHMI Prague POPs have been monitored since 1988 at the CHMI observatory in Kosetice
( http://www.chmi.cz/uoco/struct/odd/ook/index.html ).
This observatory is accepted as a background station for Central Europe and is the only one in Europe where POPs have been observed not only in ambient air, but also in wet atmospherical deposition, surface waters, sediments, soils, mosses, and needles (integrated POPs monitoring).
The monitoring is a part of the UN ECE CRLTAP (Convention on Long-Range Transboundary Air Pollution) and its EMEP programme. Polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorinated pesticides (OCPs) are observed in stated matrices, ambient air sampling takes place once a week. Such concept corresponds to the "superstations" network according to the SC and CRLTAP and the Kosetice observatory can join such network immediately.
A high-volume pumping device has been commonly used for air sampling and subsequent POPs analysis - for example PS-1 type (manufacturer Thermo-Andersen, USA).
Two discs are placed in its sampling heads - quartz disc and pretreated polyurethane disc (PUF). The quartz discs catch dust fraction sorbed pollutants, PUF discs catch contaminants from gas phase (US EPA methodology TO-13).
2) Passive sampling in the Czech republic ( network MONET-CZ )
Passive samplers provide information about long-term contamination of the selected site and may be used as a screening method for semiquantitative comparison of various localities. Integrative character is their main advantage, i.e. providing long-term average values with low sensitivity to short-term accidental fluctuations of pollutants concentration. It was verified that these methods can serve for obtaining data on local to continental level, from gradients between industrial and countryside areas to continental transects. Option of using these samplers in far away and unapproachable localities is another significant advantage. Therefore, they may be employed in long-term monitoring programmes, in which they may serve for identification and characterization of point sources as well as better understanding of individual primary and secondary sources effects, distribution and transport of contaminants in individual regions and among them.
The functional principle of passive sampling devices is simple. Sampling takes place by means of spontaneous diffusion of the monitored substance into the collecting medium. This process runs as a result of different chemical potentials between two media. Air is flowing around the passive disc, membrane or another medium, in which the observed pollutant is being caught. This medium is analyzed after sampling termination and the substance concentration in air is calculated. Main factors affecting sorption kinetics of passive samplers include particularly temperature, wind speed and exposure duration. Due to providing information on long-term average contamination level they are not suitable for observation of quick changes of air pollution. The disadvantages include mainly impossibility of accurate determination of passed air volume, advantages are low purchase and maintenance costs (no need for operator presence and power source), noiselessness, and low requirements for installation and technical support.
The Czech Republic is currently the only country, in which this tool has been fully developed, successfully tested, and broadly used. The method has been already employed for five years and results may thus be used for assessment of POPs occurrence trends in ambient air in the Czech Republic. The second unique property is existing range of MONET-CZ network sampling sites, whose design covers both sampling localities for long-range transport assessment and localities representing model sources as defined by the SC. Therefore, it is possible to evaluate effects of model sources and nowadays also trends characterizing efficiency of measures applied on these sources for the purpose of POPs emission reduction. While passive samplers on the basis of polyurethane foam have been used in the GAPS (Global Atmospheric Passive Sampling; http://www.msc-smc.ec.gc.ca/gaps/ ) monitoring campaign worldwide, organized as the 2-year Environment Canada project, no individual country disposes of sufficiently representative and continuously measured network of monitoring localities. Thus, long-term sustainability of the present passive air sampling network in the Czech Republic consisting of 50 sampling sites for three years is a prestigious issue of high priority. The Czech network also serves as a model for building of similar tools in other countries, particularly those, in which any data about air quality is completely missing. Concerning these circumstances RECETOX has run activities leading to the estabilishment of an open association of cooperating subjects that use the results and also support the monitoring network ( www.monet-cz.cz ).
It may be concluded that:
- passive samplers are able to determine occurrence and levels of POPs in ambient air
- the Kosetice observatory also serves as a calibration point, in which both sampling approaches have been employed
- they suitably supplement available data from active sampling, because they provide continuous, monthly-averaged information
- provide information about spatial and time trends at other localities in comparison to the "superstation" in Kosetice
References
Bartoš 2003: M.Sc. thesis - Toxafen. May 2003.
Bidleman, T. F. (1999): Atmospheric transport and air-surface exchange of pesticides. Water, Air and Soil Pollution 115, 115-166.
Cousins, I. T., Jones, K. C. (1998): Air-soil exchange of semi-volatile organic compounds (SOCs) in the UK. Environ. Pollut. 102, 105-118.
Hafner, W.D., Hites, R.A. (2003): Potential sources pesticides, PCBs, and PAHs to the atmosphere of the Great Lakes. Environ. Sci. Technol. 37, 3764-3773.
Harner, T., Mackay, D., Jones, K. C. (1995): Model of the Long-Term Exchange of PCBs between Soil and the Atmosphere in the Southern UK. Environ. Sci. Technol. 29, 1200-1209.
Hermanson, M. H., Christensen, E. R., Buser, D. J., Chen, L. M. (1991): Polychlorinated-Biphenyls in Dated Sediment Cores from Green Bay and Lake-Michigan. J. Great Lakes Res. 17, 94-108.
Hillery, B. R., Basu, I., Sweet, C. W., Hites, R. A. (1997): Temporal and spatial trends in a long-term study of gas phase PCB concentrations near the Great Lakes. Environ. Sci. Technol. 31, 1811-1816.
Holoubek, I., Adamec, V., Bartoš, M., Bláha, K., Bláha, L., Budňáková, M., Černá, M., Čupr, P., Demnerová, K., Drápal, J., Hajšlová, J., Hanzálková, M., Holoubková, I., Hrabětová, S., Jech, L., Klánová, J., Kohoutek, J., Kužílek, V., Machálek, P., Matějů, V., Matoušek, J., Matoušek, M., Mejstřík, V., Novák, J., Ocelka, T., Pekárek, V., Petira, O., Petrlík, J., Provazník, J.,Punčochář, M., Rieder, M., Ruprich, J., Sáňka, M., Tomaniová, M., Vácha, R., Volka, K., Zbíral, J. (2005): Návrh Národního implementačního plánu pro Implementaci Stockholmské úmluvy v České republice. Projekt GF/CEH/01/003: ENABLING ACTIVITIES TO FACILITATE EARLY ACTION ON THE IMPLEMENTATION OF THE STOCKHOLM CONVENTION ON PERSISTENT ORGANIC POLLUTANTS (POPs) IN THE CZECH REPUBLIC. TOCOEN, s.r.o., Brno v zastoupení Konsorcia RECETOX - TOCOEN & Associates, TOCOEN REPORT No. 252, Brno, říjen 2005, 100 s + 23 s souhrnu + 11 příloh, http://recetox.muni.cz/projekty/Unido/unido-NIP.htm
Ma, J. M., Hung, H., Blanchard, P. (2004): How do climate fluctuations affect persistent organic pollutant distribution in North America? Evidence from a decade of air monitoring. Environ. Sci. Technol. 38, 2538-2543.
Simcik, M. F., Basu, I., Sweet, C. W., Hites, R. A. (1999): Temperature dependence and temporal trends of polychlorinated biphenyl congeners in the Great Lakes atmosphere. Environ. Sci. Technol. 33, 1991-1995.
Wania, F. (2003): Assessing the potential of persistent organic chemicals for long-range transport and accumulation in polar regions. Environ. Sci. Technol. 37, 1344-1351.
Materials from the 3rd Conference of the SC Parties concerning the SC measures efficiency evaluation:
Effectiveness evaluation (link: www.pops.int)
UNEP/POPS/COP.3/22 and Corr.1 - Effectiveness evaluation
UNEP/POPS/COP.3/23 - Draft implementation plan for the global monitoring plan for the first effectiveness evaluation
UNEP/POPS/COP.3/INF/14 - Guidance on the global monitoring plan
UNEP/POPS/COP.3/INF/15 - Updated information on existing human health and environment monitoring programmes
UNEP/POPS/GMP/TWG.1/6 - Report of the Provisional Ad Hoc Technical Working Group on the work of its first meeting
UNEP/POPS/GMP/TWG.2/8 - Reports of the Provisional Ad Hoc Technical Working Group on the work of its second meeting
UNEP/POPS/COP.3/INF/33* - Global project on assessment of existing capacity and capacity building needs for the analysis of persistent organic pollutants in developing countries
