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Eurobionet: Standardised
Methods for Biomonitoring
Air Quality in European
Cities
By: Andreas Klumpp, Gabriele
Klumpp and Wolfgang Ansel
Air quality in most European
cities has significantly improved during the last decades as a consequence of
more rigorous legal regulations, the adoption of less-polluting technologies
and the migration of industries out of the city centres. In particular, the
relevance of acidic air pollutants (winter smog) has clearly decreased during
this period. Nevertheless, air pollution continues to be a prominent
environmental problem in Europe. Continuously increasing, road traffic is a
primary culprit. Thus, air pollution by ozone and other photo-oxidants (summer
smog), but also by suspended particulate matter and potentially carcinogenic
organic air pollutants is a major concern today.
National legislation and European
directives oblige the authorities to establish air quality monitoring networks
and to record the ambient concentrations of the most important air pollutants
continuously. Such measurements are being made by physical and chemical methods
using automated monitoring stations. The data obtained from such measurements
permit control of compliance with current air quality standards and limit
values. Data on ambient pollutant concentrations, however, do not allow direct
conclusions to be drawn on potential impacts on humans and the environment.
Evidence of harmful effects can only be provided by using living organisms,
i.e. by bio-indicators. Such bio-indicators also integrate the effects of all
environmental factors including interactions with other pollutants or climatic
conditions. This permits the risk of complex pollutant mixtures and chronic
effects occurring even below threshold values to be assessed.
Bio-indicator plants have been
used in scientific investigations on air pollution effects for many years. In a
few countries such as Germany, Austria or The Netherlands, some of these
methods are also being applied by environmental authorities and private
enterprises for routine monitoring of industrial installations and urban
agglomerations. At the European level, however, the use of bio-indicator plants
to assess air pollution effects is not very well established. The insufficient
standardisation of the techniques and consequently the low comparability of the
results is one of the major reasons for the poor acceptance of this
effect-related methodology of air quality monitoring by policy makers, public
administration and the private sector.
The principles adopted by the
Earth Summit held at Rio de Janeiro in 1992 ensure the citizens' right of
appropriate access to information concerning the environment. This right was
confirmed by the UNECE Aarhus Convention in 1998. The free access of citizens
to environmental data and the commitment of public institutions to provide
sufficient and extensive information raise the question of how complex issues
like the distinction between "good", ozone in the stratospheric ozone layer and
"bad" ozone at the earth's surface can be explained to laypersons
appropriately. As a consequence, the demand for efficient and attractive
communication strategies in the environmental sector is increasing.
Bio-indicator plants feature
several properties that qualify them not only for the effect-oriented
monitoring of air quality but particularly for environmental communication and
education. Frequently, they reveal the detrimental effects of air pollutants
directly, i.e. visibly to the naked eye, by responding to the environmental
impact with apparent injury symptoms. They make these problems, which are
normally quite abstract, visible and understandable to people directly and
within their everyday life. They address people emotionally as evident plant
damages may evoke a personal concern and prompt conclusions on potential air
pollution effects on one's own well being.
EuroBionet: A Network of
Authorities, Science and the Public
This was the background for the
implementation of the "European Network for the Assessment of Air Quality by
the Use of Bio-indicator Plants" (EuroBionet) in 1999 with financial support by
the LIFE Environment. Programme of the European Commission. EuroBionet is a
network of local governments and research institutions from twelve cities in
eight EU member states. It addresses the use of bio-indicator plants in air
duality monitoring and environmental awareness-raising of the urban population.
Under the scientific and technical coordination of the University of Hohenheim
(Germany), participants in this project include the cities of Edinburgh (GB),
Sheffield (GB), Copenhagen (DK), Dusseldorf (D), Valencia (E), Ditzingen (D),
Klagenfurt (A), Verona (I) and Glyfada (GR), the regions of Grand Nancy (F) and
Grand Lyon (F) as well as the Province of Catalonia (E), together with their
scientific partners. The scientific and communicative objectives of the project
are to establish the use of bio-indicator plants at the European `level, to
contribute to the standardisation of methods and to the transfer of expertise
and knowledge, to analyse and evaluate the urban air quality in Europe, to
compare pollution types among different cities and regions, to, demonstrate the
effects of air pollutants , in a way easily comprehensible for laypersons, to
contribute to a sensitisation of the urban population towards environmental
issues, to stimulate initiatives in schools, companies, public authorities and
private households, and to provide tools for 'green' urban marketing. In order
to use synergy in achieving these goals, a powerful integration of science,
administration and the broad public, particularly schools, was aimed at from
the onset.
Bio-indicators in Air Pollution
Control
Based on the knowledge of the
present air pollution situation in cities, bio-indicator plants to assess
ozone, sulphurous compounds, heavy metals, polycyclic aromatic hydrocarbons,
and mutagenic substances were chosen. In each of the participating cities,
local networks of eight to ten bio-indicator stations were established and
operated for three years. The stations included urban and suburban sites, sites
close to streets with heavy traffic as well as reference sites with low
pollution load. At these sites, bio-indicator plants were exposed to ambient
air to assess the effects of air pollutants. Cultivation and exposure of plants
as well as injury assessment and sampling was done according to a common
instruction manual to ensure a high degree of standardisation. Additional
quality control was done by organising courses and training working groups on
site.
Ozone: A Gradient through Europe
The experiments with the
ozone-sensitive tobacco (Nicotiana tabacum) variety Bel-W3 demonstrated
a very clear gradient of O3 impact, with increasing plant injury
levels from the North and Northwest of Europe to Central and Southern regions.
The lower intensity of solar radiation in the United Kingdom, Denmark and
North-western Germany resulted in reduced atmospheric O3 formation
and consequently in only weak to moderate ozone-induced injuries. The climatic
conditions in Central and Southern Europe, however, favoured the O3
formation and hence the development of strong ozone damage in bio-indicator
plants. Local emission conditions and large-scale atmospheric transport
processes additionally influenced the degree of ozone pollution at the
individual sites. The analysis of air pollution data from automated measuring
stations documented that the threshold and target values of the World Health
Organisation (WHO) and the EU were clearly exceeded in most of the cities. As
climatic factors influence the response of plants to ozone, there are no
generally accepted relationships between ambient ozone pollution and the degree
of ozone-induced plant damage. Overall, however, a good correspondence in the
geographical distribution pattern of leaf injuries and atmospheric ozone
concentrations was found.
Mutagenic Substances: Successful
Test Campaigns of a New Methodology
In spiderwort (Tradescantia
clone #4430), mutagenic substances cause chromosome damage in the pollen mother
cells of certain development stages after a few hours of exposure. The
resulting formation of so-called micronuclei can be scored microscopically and
serves as a measure for mutagenic effects. This Tradescantia-Micronucleus-Test
has now been tested over such a large geographical extension for the first
time. The test campaigns provided important hints on the occurrence of
mutagenic substances in the urban environment. Elevated micronuclei formation
was found particularly along heavy trafficked roads, clearly suggesting the
need for more detailed investigations on the genotoxic potential of traffic
emissions.
Heavy Metals: Local Hot Spots due
to Traffic and Industrial Emissions
Standardised grass cultures using
Italian rye grass (Lolium multiflorum) are relatively resistant to air
pollutants, but very efficiently accumulate different toxic substances. Based
on the accumulation rates in rye grass, it is possible to draw conclusions on
the pollution load by sulphurous compounds, heavy metals and organic substances
and on the potential, risk these elements pose to the food chain..
As opposed to the impact by
photo-oxidants, no large-scale geographical pattern of heavy metal pollution
was found in our project. Moreover, the situation was characterised by a
small-scale distribution of the pollutants in the direct neighbourhood of local
emission sources. The exposed rye grass cultures, e.g., revealed a local hot
spot of heavy metal pollution due to industrial emissions in one of the cities.
More than fifty-fold increased chromium concentrations and elevated levels of
several other heavy metals at a single bio-indicator site were very probably
ascribed to the emissions of neighbouring heavy industry facilities. This
example demonstrates that screening studies with bio-indicator plants are very
useful to determine local hot spots of air pollution, which can then be
investigated in more detail.
In most of the other local
networks, by contrast, the heavy metal accumulation in the grass cultures was
dominated by traffic emissions. Sites at roads or crossings with intense
traffic generally exhibited the highest chromium, copper, iron, and lead
concentrations. The accumulation of antimony, a semi-metal released from the
brake linings of cars, proved to be particularly characteristic of
traffic-influenced sites. The lead levels in grass cultures, on the other hand,
were normally very low; this demonstrates the positive environmental
consequences of introducing unleaded petrol in the EU. In accordance with the
only recent ban of leaded petrol in Spain, the lead levels in rye grass
remained high in the Spanish cities until summer 2001 and rapidly declined by
2002. This example proves that bio-indicators are adequate means to assess even
short-term changes of the pollution situation.
A Broad Range of Different Organic
Pollutants
Curly kale (Brassica oleracea)
accumulates organic air pollutants such as polycyclic aromatic hydrocarbons (PAH)
in its waxy leaves. In the EuroBionet project, 20 different PAH compounds were
analysed, among them the potentially carcinogenic benzo(a)pyrene. Similar to
the results with heavy metals, a clear distinction was found between PAH levels
of urban and rural sites. In general, the values were in an intermediate range.
The highest values of total PAH compounds as well as of benzo(a)pyrene were
again detected at sites with heavy traffic. This indicates that, in urban
areas, traffic emissions are an important source of this pollutant category as
well.
Bio-indicators as Green
Ambassadors
For publicity campaigns, a
modular, centralised communication concept was developed for the decentralised
implementation in the partner cities. The "local experience idea" has been the
main element of this concept. It aimed at establishing central sites in the
cities where environmental problems could be rendered visible and
comprehensible for laypersons. This concept has been implemented in the form of
a green cubic information pavilion (Green Box'), which has been staging the
otherwise unimposing bio-indicator plants and thus served as the starting point
for further communicative activities. The sheer size and colour of the box
attracted attention. In the same way that a construction wall arouses the
curiosity of passers-by, the big green box induced people to come a little
closer to find out what might be going on behind the green walls. Peep holes in
the walls allowed a look inside the pavilion where a bio-indicator station and
information boards explaining the objectives and methods of the project as well
as local environmental problems and their possible solutions could be seen.
The scientific investigations and
the presentation in the green information pavilions have been accompanied by
intensive press campaigns. Using the bio-indicator plants and particularly the
heavily ozone-damaged tobacco plants enabled the journalists to illustrate and
present otherwise complex and abstract issues like air pollution and air
quality in a visually attractive and emotive way. Hence, the publications on
experiments with bio-indicator plants frequently became the peg to hang on more
detailed reports dealing with "Air Pollution and Mobility", issues that clearly
exceed the restricted field of bio-indication research.
Stimulating the environmental
awareness of children and teenagers has been another important component of the
communication concept. For this purpose, a pilot school project was initiated
in which students of different age groups participated. Depending on the age
group, the classes were variously involved in different project activities. The
students took care of the indicator plants exposed at stations on schoolyards,
performed growth measurements and assessed air pollution-induced injuries.
Thus, for the first time the detrimental effects of air pollution on plants
became visible and comprehensible in the youngsters' own environment. In a
further step, the students acted as multipliers. On various occasions, they
presented the methods, results and conclusions of the school project to the
public using their own information stands. On poster walls, the population was
informed about the harmful effects of ozone and its formation from precursor
substances emitted by cars. This underlined the responsibility of each
individual for maintaining and improving air quality. Particularly the
bio-indicator plants as "living measuring instruments" were instrumental in
calling the attention of the citizens. All the activities conducted by the
children and teenagers found public approval and were accompanied by an
intensive publicity campaign. The publications in official bulletins and in
newspapers created positive feedback and thus boosted the educational effects.
The experience gained with these
activities confirmed that bio-indicator plants are a very useful tools to pick
out different aspects of air pollution and their consequences for humankind and
the environment as a central educational theme for children and teenagers of
all age groups. The students' own experience of the harmful effects of air
pollution provoked personal concern; this served as a basis for debates on this
topic and on potential solutions. The contact with plants, as living organisms,
proved to be very suitable to demonstrate the relationships between traffic,
air pollution and environmental damage to young people. This approach seemed to
leave much more lasting impression than abstract technical statistics on
pollutant concentrations.
EuroBionet as an Example
For the first time, extensive
information on the effects of urban air pollution on bio-indicator plants has
been obtained in a highly standardised way. This has yielded a broad data
collection on the pollution load of European cities by a wide range of
pollutants. The methods proved to be a very suitable tool to document the
spatial and temporal distribution of the pollution impact as well as its
short-term modifications. Thus, they enable an efficient verification of the
success of emission reduction measures. Moreover, EuroBionet has decisively
helped to standardise methods on a European level and thus permanently
establish this biological method of environmental monitoring.
The modular communication concept
enabled us to successfully draw public attention to urban air pollution as a
key environmental problem in Europe. Hence, the tasks and activities of
European environmental authorities came to the public eye. Environmental topics
were identified as a central theme and intensively discussed by interested
citizens, schools, public authorities and particularly by the press and radio
programmes.
The success of EuroBionet serves
as an example for the use of bio-indicator plants in environmental monitoring
and communication inside the EU, but has great potential in developing
countries as well. The high degree of standardisation achieved in this project
demonstrates that a Europe-wide use of such biological methods of air quality
monitoring is feasible and recommendable. The methods applied in EuroBionet may
serve as a basis for future European guidelines. They have already been
incorporated by similar projects in Hungary and Poland and are also a component
in environmental monitoring programmes being planned or already established in
developing countries such as Ethiopia, Brazil or China. The model character of
EuroBionet is particularly obvious in the fields of environmental communication
and education. The modular communication concept may easily be transferred to
other regions or used for different purposes. The educational concepts and
methods have already been adopted by various schools throughout Europe.
Prof Andreas Klumpp, Drs. Gabriele
Klumpp and Wolfgang Ansel are associated with the Institute for Landscape and
Plant Ecology, University of Hohenheim, D-70593 Stuttgart, Germany. |
