Mutagenicity analysis of water samples from Seydisuyu (Kırka, Turkey) stream under the influence of boron production complex

Inhibition of boric acid and sodium borate on the biological activity of microorganisms in an aerobic biofilter

The aim of this work was to study the inhibition effect of boric acid and sodium borate on the treatment of boron containing synthetic wastewater by a down flow aerobic fixed bed biofilm reactor at various chemical oxygen demand (COD)/boron ratios (0.47-20.54). The inhibitory effect of boron on activated sludge was evaluated on the basis of COD removal during the experimental period. The biofilter (effective volume = 2.5 L) was filled with a ring of plastic material inoculated with acclimated activated sludge. The synthetic wastewater composed of glucose, urea, KH2PO4, MgSO4, Fe2 SO4, ZnSO4 x 7H20, KCl, CaCl2, and di-sodium tetraborate decahydrate or boric acid (B = 100-2000 mg L(-1)). The biological treatment of boron containing wastewater resulted in a low treatment removal rate due to the reduced microbial activity as a result of toxic effects of high boron concentrations. The decrease in the COD removal rate by the presence of either boric acid or sodium borate was practically indistinguishable. It was observed from the experiments that about 90-95% of COD removal was possible at high COD/boron ratios.

Oxidative stress-mediated genotoxicity of wastewaters collected from two different stations in northern India

Oxidative stress-mediated genotoxicity of wastewaters taken from two different cities, Saharanpur (SWW) and Aligarh (AWW), were compared with a battery of short-term assays namely the Allium cepa genotoxicity test, the plasmid-nicking assay, and the Ames fluctuation test. Both test-water samples - when used undiluted - increased the frequency of chromosomal abnormalities and/or micronuclei and alterations in the mitotic index of root cells of Allium cepa. Bridges and fragmentation of the chromosome were the predominant effects of the Saharanpur water sample while the Aligarh sample induced mainly chromosome fragmentation. Single- and double-strand breaks were also observed in plasmid DNA treated with these test wastewaters. The plasmid-nicking assay performed on SWW resulted in linearization of plasmid DNA when 18μl was tested (in a total reaction volume of 20μl). However, with the same amount of AWW, all three forms of plasmid, viz. supercoiled, open circular and linear were observed. Supplementation with specific scavengers of reactive oxygen species (ROS) caused a significant decline in mutagenicity of test-water samples in all the tests, pointing at oxidative stress as the mediator of the observed genotoxicity. The role of heavy metals in the AWW-induced oxidative stress and that of phenolics in SWW cannot be ruled out.

Genotoxicity testing and biomarker studies on surface waters: an overview of the techniques and their efficacies

Rapid industrialization, use of modern agriculture practices, and fast urbanization vis-a-vis indiscriminate use of xenobiotics have led to the serious problems of water pollution in India and abroad. The complexicity of the pollutants in environmental samples demands a multitude of genotoxicity testing with increasing simplicity, sensitivity, and affordability. Moreover, various pollutants mutually affect their own toxic behavior, which complicates the problem of risk assessment. An overview, highlighting the genotoxicity testing system, such as Ames plate incorporation test, Ames fluctuation test, E. coli survival assay, Allium cepa toxicity/genotoxicity test, comet assay, and plasmid nicking assay, is presented in this article, and a comparison has been made to estimate the efficacy of these genotoxicity bioassays performed on some surface waters. Some work on toxicity biomarkers vis-a-vis studies on surface waters has also been included in the present review.