Traffic-related air pollution biomonitoring with Tradescantia pallida (Rose) Hunt. cv. purpurea Boom in Brazil.

Abstract

This study aimed to verify the capacity of Tradescantia pallida in the biomonitoring of air pollution in urban areas with different traffic intensities and under varying environmental conditions. Experiments were carried out in Ribeirão Preto, in the Southeastern Brazil, with more than 660,000 inhabitants and a fleet of more than 485,000 motor vehicles. Ten seedlings of T. pallida were exposed in three areas in the city, differing in traffic vehicle flow, in two seasons (wet and dry). At the end of each sampling period, which lasted 4 months, samples of leaves were collected, and the content of As, Ba, Ca, Cd, Cr, Cu, Fe, Hg, Mg, Mn, P, Pb, S, and Zn was determined by inductively coupled plasma mass spectroscopy (ICP-MS). The same elements were determined in soil samples for a seasonal characterization in conjunction with secondary data of environmental parameters. Additionally, micronucleus assay with early pollen tetrad cells of Tradescantia (Trad-MN) was conducted by collecting flower buds and analyzing the micronuclei frequencies in pollen mother cells. Although pollutant levels in air were below the Brazilian legal limits, plants exposed in the high-traffic flow area presented higher concentrations of elements related to vehicle emissions, especially under dry conditions, and higher micronuclei frequency in pollen mother cells. These results show the sensitivity of T. pallida to low-level urban air pollution and its suitability as bioindicator for trace elements. This alternative tool for biomonitoring can serve as a support methodology for the adoption of more restrictive public environmental policies in Brazil and extendible to other developing countries.