Biomonitoring of air quality in the Bodoquena microregion, Mato Grosso Do Sul: mutagenic and morphoanatomical alterations in Tradescantia pallida (rose) D.R. Hunt var. purpurea

The objective of this study was to assess air quality in relation to vehicular traffic flow in cities located at different elevations in the Bodoquena microregion, state of Mato Grosso do Sul, Brazil. To do so, a micronucleus test was carried out using the TRAD-MCN bioassay on young Tradescantia buds collected from February to November 2018 in seven cities of the microregion with different traffic flow intensities. Meteorological parameters were evaluated, and vehicular traffic was counted to determine traffic flow in each city. With data from the Shuttle Radar Topography Mission (SRTM) and processing in Esri ArcGIS® software version 10.5.1, the regions was mapped based on an Elevation Model. Morphoanatomical analyses were performed according to standard methodology. Measurements were taken of thickness, length and width of tissues and structures, including the upper and lower cuticle, upper and lower epidermis, hypodermis and mesophyll. The greatest traffic flow was found in the cities of Bodoquena, Guia Lopes da Laguna, Jardim, and Porto Murtinho, with the period from 5:00 to 6:00 p.m. showing the highest traffic flow. The greatest frequency of mutagenic alterations was found in the city of Guia Lopes da Laguna, although the results did not differ significantly from Bonito, Caracol, and Jardim. Throughout the biomonitoring, the summer and autumn seasons showed the greatest micronuclei frequencies in all evaluated cities. Variations in the tissue/structure thickness was observed across cities and seasons, but with a decrease in thickness during autumn. In general, the tissues/structures were smaller for the cities of Nioaque and Porto Murtinho, while the anatomical and morphological characteristics of leaf length and thickness showed no differences among cities. We found limited correlation between micronuclei frequency and traffic flow, supporting the hypothesis that although mutagenic alterations are observed in T. pallida, in this microregion the changes are numerically lower when compared to other regions of the state. In light of the genotoxic and morphoanatomical factors assessed herein, the Bodoquena microregion appears to be well preserved in terms of air quality, presenting low micronuclei frequency and a limited reduction in tissues and leaf structures, regardless of the season.