Tradescantia micronucleus test indicates genotoxic potential of traffic emissions in European cities.

Urban atmospheres contain complex mixtures of air pollutants including mutagenic and carcinogenic substances such as benzene, diesel soot, heavy metals and polycyclic aromatic hydrocarbons. In the frame of a European network for the assessment of air quality by the use of bioindicator plants, the Tradescantia micronucleus (Trad-MCN) test was applied to examine the genotoxicity of urban air pollution. Cuttings of Tradescantia clone #4430 were exposed to ambient air at 65 monitoring sites in 10 conurbations employing a standardised methodology. The tests revealed an elevated genotoxic potential mainly at those urban sites which were exposed to severe car traffic emissions. This bioassay proved to be a suitable tool to detect local 'hot spots' of mutagenic air pollution in urban areas. For its use in routine monitoring programmes, however, further standardisation of cultivation and exposure techniques is recommended in order to reduce the variability of results due to varying environmental conditions.

Influence of climatic conditions on the mutations in pollen mother cells of Tradescantia clone 4430 and implications for the Trad-MCN bioassay protocol.

The present was study aimed at investigating the influence of relative humidity and temperature on spontaneous and pollution-induced mutation rates during exposure and recovery periods in the Trad-MCN test. Cuttings of Tradescantia clone 4430 were exposed to a negative control, to 4 mM maleic hydrazide (MH), and to a polluted water sample under varying conditions of air temperature and humidity in climatic chamber experiments. The relative humidity did not affect the spontaneous mutation rate in the clone investigated, but was negatively correlated with the frequency of pollution-induced mutations. Low temperature caused an increase in the number of micronuclei in the negative control, but no comparable response in polluted samples. At an extremely high temperature, signs of strong physiological damage and/or of a meiotic delay of pollen maturation were detected. When the temperature increased gradually and the extreme value was maintained only for short time, such detrimental effects were not observed. Subsequent treatment with high and low temperatures, by contrast, resulted in the highest MCN rates of all experiments. Our studies point to the possibility of producing irregular results of the Trad-MCN test if the influence of climatic factors has not sufficiently been considered.

Bioindication of air pollution effects near a copper smelter in Brazil using mango trees and soil microbiological properties.

A field study near the copper smelter of a large industrial complex examined air pollution effects on vegetation and soil parameters in Camaçari (northeast Brazil). Close to the smelter, soil pH-value was lower and total acidity as well as organic carbon contents were higher compared with a site far from the source and two reference sites. The acidification of top soil particularly and the drastically enhanced plant-available copper concentrations were caused by atmospheric deposition. High sulphur and copper deposition significantly reduced microbial biomass and altered functional diversity of soil microorganisms (arylsulphatase and xylanase). Large accumulations of sulphur, arsenic and copper were detected in mango leaves (Mangifera indica) growing downwind from the smelter suggesting potential food chain-mediated risk.

Air pollution impact on the Atlantic forest in the Cubatäo region, SP, Brazil

The rain forest covering the slopes of the Serra do Mar mountains, in the vicinity of Cubatão, SP, has been damaged by a variety of air pollutants emitted by the industrial complex established in the region. In a study by the Instituto de Botânica (São Paulo) and the Universities of Essen and Kassel (Germany) sensitive and cumulative indicator plants were explosed to the environment in an active biomonitoring program, in order to get information on the current air pollution situation and on the spatial and temporal distribution of air pollutants in the region, draw conclusions on the causes of vegetation damage, and facilitate risk prognosis. Native plant species, indigenous to the ecosystem were also studied (passive biomonitoring), in order to evaluate the present state of the vegetation, the effects of air pollution on plant vitality and detect mechanisms of pollution resistance. Both kinds of biomonitoring were performed in four sites: Pilões river valley, Caminho do Mar, Mogi river valley and Paranapiacaba, which are located at different altitudes, at various distances from pollution sources and consequently receive different kinds and loads of air pollution. Based on our results, fluorides, sulfur and metals are considered the main causes of the forest decline at the Mogi valley, whereas ozone. PAN and sulfur are implicated at Caminho do Mar. Native tree species show several chemical and biochemical alterations caused by the air pollution impact, that give information on their resistance or sensitivity to air pollution.