Active monitoring of urban air with a simple short-term Tradescantia pallida var. purpurea bioassay under different temperature conditions

Abstract

The aim of this study was to investigate the influence of temperature regimes on the formation of micronuclei, and to assess the efficiency of a simple short-term exposure of Tradescantia pallida var. purpurea cuttings maintained in distilled water for in situ monitoring of air genotoxicity during different climatic seasons. The first experiment tested the effect of four temperature regimes and a reference temperature on the formation of micronuclei in growth chambers. For the second experiment, plant cuttings kept in distilled water were periodically exposed for 24 hours, from spring 2010 to winter 2011, in an urban site in the municipality of Novo Hamburgo, in the Sinos River Basin, State of Rio Grande do Sul (Brazil); in addition an indoor control was carried out. Micronuclei frequencies (MCN) were determined in young tetrads of pollen mother cells and expressed as MCN/100 tetrads. The MCN frequencies varied from 0.70 to 1.17, however there was no significant difference between the different temperature regimes (minimum and maximum temperatures of 6 and 38 °C) and the temperature of 26 °C. Under field conditions, MCN frequencies were significantly higher in samples from the urban site than in those from the control and did not vary significantly among seasons (4.0 in spring, 2.9 in summer, 3.1 in autumn and 4.3 in winter). The results indicated the validity of this simple method as a suitable experimental model for active air monitoring under the environmental conditions of the study.