Genotoxicity biomonitoring of sewage in two municipal wastewater treatment plants using the Tradescantia pallida var. purpurea bioassay

Abstract

The genotoxicity of untreated and treated sewage from two municipal wastewater treatment plants (WTP BN and WTP SJN) in the municipality of Porto Alegre, in the southern Brazilian state of Rio Grande do Sul, was evaluated over a one-year period using the Tradescantia pallida var. purpurea (Trad-MCN) bioassay. Inflorescences of T. pallida var. purpurea were exposed to sewage samples in February (summer), April (autumn), July (winter) and October (spring) 2009, and the micronuclei (MCN) frequencies were estimated in each period. The high genotoxicity of untreated sewage from WTP BN in February and April was not observed in treated sewage, indicating the efficiency of treatment at this WTP. However, untreated and treated sewage samples from WTP SJN had high MCN frequencies, except in October, when rainfall may have been responsible for reducing these frequencies at both WTPs. Physicochemical analyses of sewage from both WTPs indicated elevated concentrations of organic matter that were higher at WTP SJN than at WTP BN. Chromium was detected in untreated and treated sewage from WTP SJN, but not in treated sewage from WTP BN. Lead was found in all untreated sewage samples from WTP SJN, but only in the summer and autumn at WTP BN. These results indicate that the short-term Trad-MCN genotoxicity assay may be useful for regular monitoring of municipal WTPs.

Biomonitoring of water genotoxicity in a Conservation Unit in the Sinos River Basin, Southern Brazil, using the <italic>Tradescantia</italic>micronucleus bioassay

“…MCN frequency variations along time draw attention to the importance of monitoring at various time points throughout the year. Although the Trad-MCN bioassay may be sensitive to environmental variables, as discussed in studies about the genotoxicity of atmospheric air (Savóia et al, 2009;Costa and Droste, 2012) and of wastewater treatment plants (Thewes et al, 2011), MCN frequency variations in the present study were not associated with rainfall. The influence of rain on the genotoxic potential of water bodies has to be investigated more extensively, since there are records of lower MCN frequencies in Tradescantia pallida var.…”

“…The influence of rain on the genotoxic potential of water bodies has to be investigated more extensively, since there are records of lower MCN frequencies in Tradescantia pallida var. purpurea exposed to sewage of wastewater treatment plants (Thewes et al, 2011) and in Allium cepa exposed to water from the Sinos River, Brazil (Oliveira et al, 2012) after periods of precipitation.…”

“…Seven slides were prepared for each sample, and the number of MCN in a random set of 300 tetrads per slide was scored under 400× magnification (Olympus CX4 microscope). MCN frequencies were calculated by dividing the total number of micronuclei by the total number of tetrads scored, and the results were expressed as MCN/100 tetrads (Thewes et al, 2011).…”

“…Hunt var. purpurea Boom, a wild species that is well adapted to subtropical and tropical climates, has a high sensitivity to genotoxic agents and has been used to monitor water bodies and residual waters of domestic sewage (Umbuzeiro et al, 2007;Mielli et al, 2009;Thewes et al, 2011). In this study, the genotoxicity of water bodies in the PMHLR Conservation Unit was biomonitored for one year using the Trad-MCN bioassay.…”

Bioassays with Plants in the Monitoring of Water Quality

“…Results of both cytogenetic tests should be expressed in terms of number of breaks per cell or per 100 cells. The Vicia root tip mitotic test is reliable, efficient, and relatively inexpensive [12]. A collaborative study involving laboratories in six countries was initiated under the sponsorship of the International Programme on Chemical Safety (IPCS) to determine the sensitivity, efficiency and reliability of the Vicia faba root tip meristem chromosomal aberration assay using a standardized protocol.…”