Strategic Aspects of POP monitoring
—тратегические аспекты мониторинга —ќ«
by Hoffmann M., Galagan A.A., Mykhaylenko V. P., Godina O. O. and Seleznev, A. N.
Centre of Environmental Monitoring of Ukraine (CEMU), Kyiv
работе обсуждаютс€ вопросы географического распределени€ и
биоаккумул€ции —ќ« в зависимости от их физико-химических и
микробиологических свойств. ѕредставлены первичные результаты
мониторинговых исследований ѕ’Ѕ, начатых ÷ентром в дельте ƒуна€.
ќбсуждаютс€ вопросы распределени€ и деградации ѕ’Ѕ в исследованных
образцах на примере гомологов, существующих в виде 209 различных
конгенеров. ѕоказано вли€ние количества атомов хлора на их
биоаккумул€цию и последующую деградацию. ѕриведенные рассуждени€ могут
быть полезны дл€ составлени€ плана мониторинговых исследований.
Persistent organic pollutants
(POPs) are known to be dangerous not only because of their toxicity and
resistance against degradation. One of the main problems is their
worldwide distribution in the environment, in food chains and even in
humans. In the US and the EC, POP concentration in human fat tissue and
breast-milk has reached unexpected high concentrations. It was
discussed if breast-feeding of babies can still be recommended. If one
considers human bodies (hypothetically) as waste, they would have been
to be treated as Уspecial refuseФ requiring a waste deposit place for
dangerous materials. Fortunately, newer investigations have shown that
the concentration of PCBs for example has already decreased in western
countries due to counter measures.
require sophisticated action plans that are based on the knowledge of
POP occurrence in our environment. To gain this knowledge, it is
necessary to monitor POPs all over the country in various environmental
media for some time. This would be a huge task and would require a
corresponding financial basis. It is therefore necessary to reduce the
investigation volume and to set priorities.
Setting monitoring priorities concerns several aspects as
Place of production
Transport and storage
Place of use
Physical, chemical and biological influences on the further fate and distribution
2. Physico-chemical and biological behaviour of POPs
presentation will highlight a few aspects only that are connected to
the fourth item (see above). As an example, PCB have been chosen for
further consideration in this paper. Fig. 1 shows the potential
distribution paths of PCBs .
Fig. 1: Pathways of PCB distribution in the environment 
potential distribution of PCBs through wind and water currents and
erosion depends from the physico-chemical characteristics of those
- Structure and size of molecules
- Temperature of freezing and boiling
- Evaporation curve and volatility from water
- Fat and water solubility (measured as octanol-water partitioning coefficient)
- Adsorption and desorption
- Density, viscosity, permeability
- UV and light sensitivity
- Hydrolyse (depending on pH)
further fate of PCBs and also other POPs depends on their resistance
against abiotic degradation (connected to the above mentioned
parameters) and against biotic degradation. The biological
degradability very much depends from the same parameters as
temperature, solubility, adsorption, permeability etc. One of the main
factors however is the degree and type of chlorination. This factor has
an influence on the distribution of POPs and their possible toxicity
and degradation. It is therefore also an important strategic aspect for
designing a monitoring program. Again PCB have been selected as example
because they are widespread and highly dangerous for human health. The
following figure shows the structure formula of the molecule.
Fig. 2: PCB molecule with figures indicating the possible Cl-positions 
Biphenyls (PCB) appear in the form of 209 Congeners (different
molecules) with molar masses between 189 and 499 depending on the
number of chlorine atoms; the table lists the possible number of
Table 1: PCB homologes and number of congeners in each homolog 
of the big number of possible variants, a system of sequential numbers,
called "BZ Numbers" , for the 209 PCB congeners was introduced
providing a method of identifying a given congener simply, precisely,
and accurately. Today, the scheme of the International Union of Pure
and Applied Chemistry (IUPAC) is commonly used. It overtook the same BZ
numbers but changed the name of congeners in several cases.
are produced and used as a mixture of congeners and can be found in
special oils, colours, transformers, also in households, e.g. as
softener in plastics. If the congener mixture is Уhighly halogenatedФ
(up to 60 % of chlorine content) it will not be flammable anymore. This
is why PCB were used mainly in open and closed systems to protect
against fire. In Germany for example since 1972, the use of PCB is
restricted to closed systems, in 1983 the production of PCB was
terminated. Congeners with 1 to 4 Cl-atoms (< ~ 30 % Cl) are called
Уweakly halogenatedФ. Compared with Уweakly halogenatedФ PCB, Уhighly
halogenatedФ PCB are
- less soluble in water (more lipophil)
- stronger enriched in the food chain
- less degradable by bacteria.
is the reason why the proportion of Уhighly halogenatedФ PCB (compared
to Уweakly halogenatedФ PCB) increases in the food chain. After
sufficient time for degradation, for example in river sediments, the
proportion of Уweakly halogenatedФ PCB can be increased. The following
table shows examples of PCB accumulation in various materials.
Table 2: Examples of PCB concentrations detected in environmental samples and milk 
|Type of sample||
|seawater (in mg/L)||
|macrophytes (water plants)||
3.2 - 4.0
|eggs of Podiceps cristatus (L.) (fish-eating bird) ||
0.01 - 1.6
|human breast milk||
0 - 10
toxicity of PCB varies very much depending on the position of the
chlorine atoms. If they are in the position 2, 6, 2Т and 6Т (compare
fig.2) the PCB are ortho-substituted. They are known to have
neurochemical and neurobehavioural effects. Non-ortho or mono-ortho
substituted PCB show toxicological effects similar to those of dioxins.
Some animals as dolphins are unable to degrade those non-ortho
substituted compounds and are therefore highly endangered to accumulate
lethal quantities .
degradation of POPs, especially of DDT and PCB, is known to be
difficult and very slowly. This difficulty is increased after
adsorption on soil particles and protection against UV radiation. The
degradation of DDT is a question of decades that of PCB lasts even
longer time. The process can be divided into following steps:
- oxidations and reductions
Fig. 3: Example scheme of PCB degradation 
The following statements are related on the degradation of PCB. In general one can say that
- the higher the chlorine contents of the compound, the more difficult the degradation process.
- The location of the Cl-atoms on the molecule is very important too: the p- and the m-configuration facilitate the degradation.
- If two neighbouring C-atoms are free of chlorine, the degradation will be easier. Free 3,4-positions are optimal for degradation.
- Hydroxy-derivates can be more toxic than the original compound.
4. Recommendations for the monitoring
monitoring program should follow the usual international standards for
planning, sampling, stabilisation and transport of samples [5, 6 and so
on]. Like heavy metals POPs are enriched on adsorbing surfaces (clay,
phytoplankton), the uptake through macrophytes is less important.
Therefore, in case of water samples, it is recommended to analyse
suspended matter (gained through centrifugation) or otherwise, if the
whole water sample is analysed, the amount of suspended matter or
phytoplankton should also be controlled.
samples have to be carefully selected. In natural waters, the local and
spatial distribution of the different sediment types should be known
and a decision been made on the depth of sediment sampling (depending
on the investigated problem). In the laboratory, sediment samples
should be sieved to exclude the biggest fraction (according to
international standards > 2 mm) and additional determinations of
УCo-factorsФ should be carried out as particle size distribution,
content of organics etc. for further ecological interpretation.
If mussels are collected, the species should be identified and their age. Both parameters have an influence on the fat content.
analytical procedures and information on the equipment complete the
picture. As it is very labor intensive to analyse all 209 congeners,
seven guide-PCB have been selected that were frequently produced and
often found in environmental samples: According to an international
agreement this concerns the PCB IUPAC Nr. 28, 52, 101, 118, 138, 153,
180. For the sum of these guide congeners (УS PCB7Ф) the European OSPAR
commission has defined threshold values for fish and mussels. For
sediments, German investigators have found that S PCB7 is critical if
450 mg/kg (dry weight) are exceeded; in case of higher values PCB can
be expected in fish as well . Comparisons with literature data will
only be possible if all monitoring methods are accurately harmonised.
- First results of Danube delta monitoring and comparisons
Monitoring of a selected number of POPs in the frame of the
Danube delta monitoring programme [8, 9] is one of the tasks that have been overtaken from the Centre of Ecological Monitoring of Ukraine. Sampling was started in autumn 2004 and will
be continued 3 times per year until 2006. The analyses of PCB were carried out by the L.I.Medved Institute of Ecohygiene and Toxicology, Kyiv. Results
of sediment analyses are related to the dry weight of the complete
sample, mussel results are related to the wet weight of the soft part and water samples have been used unchanged. Beside the compounds
listed in the following table, 8 different poly-aromatic hydrocarbons (PAH) have been additionally
3: Results of PCB analyses, given in mg/kg, from different sample types
collected in the Ukrainian part of the Danube delta. (PDK = 0.06 mg/kg;
Sanitary norm ¹4433-87 related to soil samples)
| ||Sample -à
- - - - - - - - - - - - - - - -
| ||Σ PCB||0,0308||0,0318||0,0256||0,0450||0,0231|
results show that highly chlorinated congeners as octachlorobiphenyl
have not been detected. The same is true for nonachlorobiphenyl and
decachlorobiphenyl that are not listed in the table. The sum of PCB
concentrations in the mussels (Sinanadonta woodiana ) differ very much.
In comparison with the sediment analyses they contain more highly
chlorinated compounds (heptachlorobiphenyl) than the sediments. This
can be connected to their higher fat content. On the other hand,
sediments contain more weakly chlorinated compounds as
trichlorobiphenyl. The reason could be the less lipophil character of
those compounds or the result of the beginning bacterial degradation.
water samples are also contaminated, but for an assessment of results
it is necessary to clarify further details and to await future
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Environmental Protection Agency (EPA) (2005): Polychlorinated Biphenyls
(PCBs), website, url: http://www.epa.gov/toxteam/pcbid/
- BALLSCHMITER and ZELL (1980): Analysis of polychlorinated biphenyls (PCB) by glass capillary gas chromatography. Fresenius Z. Anal. Chem. 302:20-31. 1980.
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in der marinen Umwelt (ISO/DIS 5667-19:2002
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