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Vol. 9 No. 3 - July 2003

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.

This article has been reproduced from the archives of EnviroNews - Newsletter of ISEB India.

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