ABSTRACT
New mixtures of pesticides are being placed on the market to increase the spectrum of phytosanitary action. Thus, the eco(geno)toxic effects of the new commercial mixture named Platinum Neo, as well as its constituents the neonicotinoid Thiamethoxam and the pyrethroid Lambda-Cyhalothrin, were investigated using the species Daphnia magna, Raphidocelis subcapitata, Danio rerio, and Allium cepa L. The lowest- and no-observed effect concentration (LOEC and NOEC) were measured in ecotoxicological tests. While Thiamethoxam was ecotoxic at ppm level, Lambda-Cyhalothrin and Platinum Neo formulation were ecotoxic at ppb level. The mitotic index (MI), chromosomal aberrations and micronucleus [MN] frequency were measured as indicators of phytogenotoxicity in A. cepa plants exposed for 12 hours to the different insecticides and their mixture under different dilutions. There were significant alterations in the MI and MN frequency in comparison with the A. cepa negative control group, with Thiamethoxam, Lambda-Cyhalothrin, and Platinum Neo treatments all significantly reducing MI and increasing MN frequency. Thus, MI reduction was found at 13.7 mg L-1 for Thiamethoxam, 0.8 µg L-1 for Lambda-Cyahalothrin, and 2.7:2 µg L-1 for Platinum Neo, while MN induction was not observed at 14 mg L-1 for Thiamethoxam, 0.8 µg L-1 for Lambda-Cyahalothrin, and 1.4:1 µg L-1 for Platinum Neo. The insecticide eco(geno)toxicity hierarchy was Platinun Neo > Lambda-Cyhalothrin > Thiamethoxam, and the organism sensitivity hierarchy was daphnids > fish > algae >A. cepa. Eco(geno)toxicity studies of new pesticide mixtures can be useful for management, risk assessment, and avoiding impacts of these products on living beings.
ABSTRACT
Urban afforestation can mitigate the effects of air pollution by acting as a sink for atmospheric emissions, but these emissions (e.g., combustion gases from diesel engines) can be a precursor of structural and physiological changes in higher plant species, which could compromise the success of afforestation projects. In this study, Guabiroba (Campomanesia xanthocarpa O. Berg.) plants were exposed in greenhouses to combustion gases emitted by a diesel engine over 120 days, with daily intermittent gas exposure. Every 30 days, leaf injury (chlorosis and necrosis), plant biomass and physiological/biochemical parameters (proteins, chlorophyll and peroxidase enzyme activity) were evaluated. The data obtained were used to construct a hierarchy of the sensitivity (and inversely, of the resistance or tolerance) of this higher plant species to the diesel oil combustion gases: peroxidase > biomass ≈ chlorophyll > protein > leaf injury. Variations in these parameters could be used for the early diagnosis of plant stress or as a marker for stress tolerance in trees. In the first case, a sensitive species could be used for the phytomonitoring of air quality and in the second case the lack of significant variations in these parameters would indicator tolerance of the plant species to air pollution. The results showed that Guabiroba, a plant native to the Atlantic forest, is sensitive to air pollution and could therefore be used for air quality monitoring, since all parameters analyzed were affected by the polluted air.
Subject(s)
Air Pollutants/analysis , Air Pollution , Environmental Monitoring , Gasoline , Vehicle Emissions/analysisABSTRACT
The influence of the pH and the contaminant desorption/emulsification on ozone (O3), ozone-hydrogen peroxide (O3/H2O2) and ozone-photolysis (O3/UV) oxidation reactions were performed to treat crude petroleum (CP) contaminated soil and water samples. Oxidation efficiency is also related to both free radicals formation in reaction medium (which is dependent of the pH), and contaminant availability (which is dependent of the compounds solubilization or desorption processes). Thus, batch basic processes of O3/H2O2 or O3/UV were improved with sonication system and surfactant addition. In the case of O3/H2O2 process, the reactions were performed at adjusted (pH = 11) and natural pH (free pH= 4-5). The effectiveness of the improved advanced oxidation processes were evaluated through the time-course analysis of the chemical oxygen demand (COD), biochemical oxygen demand (BOD5), and total organic carbon (TOC) values. For both improved treatment processes, CP-contaminated water samples displayed higher values for TOC removal and BOD5/COD ratios than CP-contaminated soil samples. The O3/H2O2 process provided better results than the O3/UV process regarding degradation efficiency, but the former is associated with higher treatment costs due to H2O2 consumption. Overall, oxidation treatment processes increase their efficiencies when reactions are carried out associated with solubilization and desorption systems promoted by sonication/surfactant action.
