Toxicologie environnementale et analytique

Arsenic, a poisonous metalloid, is ubiquitous in the environment, and affects nearly all organ systems of animals including humans. The present study was conducted to understand the protective role of quercetin, a natural flavonoid on arsenic-induced oxidative damage in rat brain. Forty male Sprague Dawley rats, aged between 7 to 8 weeks and weighing 150-200 g were divided into four groups viz. normal control, arsenic treated, quercetin treated and arsenic + quercetin treated. Rats in normal control group were given normal food and drinking water. Rats in arsenic treated group were given arsenic daily in the form of sodium arsenite (NaAsO2) in drinking water at a dose of 100 mg/l. Rats in the quercetin treated group were given quercetin, dissolved in distilled water, orally everyday through intubation gavage at a dose of 50 mg/kg body weight. Rats in the combined arsenic + quercetin treated group were given arsenic and quercetin in a similar manner as was given to rats belonging to arsenic and quercetin treated group. After 2 months of treatment, antioxidant defense status and changes in the brain histo-architecture were assessed. A significant increase in the levels of lipid peroxidation and a decrease in reduced glutathione levels were observed in the brain of arsenic treated rats, when compared to the normal controls. Further, decrease in the activities of antioxidant defense enzymes such as superoxide dismutase, glutathione peroxidase, glutathione-s-transferase and glutathione reductase, as well as the activity of enzyme nitric oxide synthase were detected in arsenic treated group, which however were restored to normal levels upon simultaneous treatment with quercetin. Brain tissue of arsenic treated rats, also showed changes at the histo-architectural level which were normalized on simultaneous treatment with quercetin. The study, therefore, reveals that quercetin shall prove to be beneficial in containing the neuro-toxic effects of arsenic.

Magnesium doped titanium dioxide (Mg+2-TiO2) with varying magnesium weight percentages (0.25 - 1.0 wt.%) has been synthesized by sol-gel method and is characterized by XRD, UV-Visible, XPS, SEM and FT-IR methods. XRD data has shown anatase crystalline phase in Mg+2-TiO2 catalysts indicating that Mg+2 did not influence the crystal patterns of TiO2. Absorption shift due to the presence of Mg+2 ions in the TiO2 structure is significant. SEM image revealed that doped catalyst has smaller particle size and higher surface area than undoped TiO2. FT-IR spectral study along with XPS established the substitution of Mg+2 into TiO2 lattice. The photocatalytic efficiency of the synthesized catalysts was investigated by performing photocatalytic degradation of methyl orange dye (MO) under visible light irradiation and it has been found that the Mg+2-TiO2 catalysts possess better catalytic activity than undoped TiO2. The effect of dopant concentration, pH, catalyst, dosage and pollutant concentrations was studied for obtaining optimal degradation conditions.

The present study deals with removal efficiency of the pesticide fenamiphos and chemical oxygen demand (COD) from aqueous solution by electrocoagulation method. The effects of initial pH, current density, initial pesticide concentration, salt concentration, usage of different electrolytes and temperature on the removal efficiency and COD have been investigated. The obtained results showed that fenamiphos and COD removal were 97.4% and 96.4% by using C with SS (Carbon as the anode and stainless steel as the cathode) at 60 min and were 90.3% and 88.2% by using SS with Ti (stainless steel as the anode and titanium as the cathode) at the same time. These electrodes provided a higher oxidation rate, higher current efficiency, high over potential and consume less electrical energy. The experimental data were fitted with several adsorption isotherm models to describe the electrocoagulation process. This study has been carried out to determine the feasibility of fenamiphos adsorption on carbon and stainless steel species by EC process using the Langmuir and Freundlich Isotherm. In addition, results for the fenamiphos removal kinetics at various effects show that the kinetic rates conformed to the pseudo first order kinetic model with good correlation using both electrodes.

In this study drinking water samples were collected from three sites of Arbaminch town and have been analyzed for some physico-chemical parameters like pH, electrical conductivity (EC), total dissolved solids (TDS), total suspended solids (TSS), total solids (TS), total alkalinity (TA), total hardness (TH), chloride (Cl-) and fluoride (F-). The result showed that pH, EC, TDS, TSS, TS, TA, TH, Cl- and F- ranged from 7.13 to 7.76, 210.0 to 230.5 μScm-1, 134.4 to 147.1 mg/L, 11.22 to 15.44 mg/L, 145.62 to 262.45 mg/L, 88.6 to 182.02 mg/L, 119.2 to 135.11 mg/L, 135.22 to 554.46 mg/L and 2.0 to 4.41 mg/L respectively. All the measured parameters were within the standard drinking water quality values of WHO except Cl- content in AMU sampling site and F- in all sampling sites. The level of Cl- in Secha and Sikela sampling sites were within the standard value of WHO (500 mg/L). But the level of Cl- was found beyond the standard value of WHO in AMU sampling site. Similarly the concentration of F- was found higher than the standard limit value of WHO (1.5 mg/L) in all sampling sites but within the maximum permissible values of US-EPA (4.0 mg/L) except in the AMU sampling site which is a little bit higher than the US-EPA. In general the present investigation found that the maximum parameters were not at a level of pollution.

Rose bengal (RB) is xanthene dye, that extensively used in dyeing, printing industries and also as an insecticide. It has severe toxic effects on the human health. Although there are many studies on adsorption/photodegradation of rose bengal using different reductants, it is of interest to explore the environmentally benign Fe(III)–montmorillonite (Fe(III)–Mt). Fe(III)–Mt was interacted with rose bengal (RB) solution at different pH (5-10), temperature (0-40°C) and solid-to-liquid ratio. The concentration of RB removal was estimated from its absorbance at λmax = 545 nm using UV-Vis spectrophotometer. In general, the dye removal was rapid in acidic pH and increases with temperature up to 50°C. A complete reduction through adsorption occurred within 3 min at pH 5 and 6. The time taken for complete adsorption at 0°C, 30°C and 40°C are 7 min, 5 min and 3 min respectively. The adsorption followed by immobilization of dye on the spent clay mineral was evident from FT-IR and FESEM/ EDX analysis. This adsorption process can be easily scaled-up for real system applications.

The aim of this study is to identify the characteristics of hazardous substances of coal ash and to evaluate the environmental contamination possibility in order to enable the recycling of coal ash generated in thermal power plants. Currently, the various requirements for the activation coal ash (bottom ash) thermal power plant recycling of emitters and are also required by law to be considered as the country’s environmental impact on the environment of large amounts of recycling coal ash. In South Korea’s national assembly in requesting an environmental impact if the potential for soil and groundwater that can occur when you recycle roadbed, cover soil of coal ash were performed in this study. Based on this study we intend to develop a plan to expand the use of recycled coal ash. There are 10 coal-fired thermal power plants in Korea. About 8.6 million tons of coal ash was generated from those power plants in 2012. Coal ash is composed of fly ash (82%) and bottom ash (18%). While most of the fly ash is recycled as ready-mix concrete admixtures and cement additives, bottom ash is left unused in landfill located within power plant. So, in this study we assessed the recyclability of the bottom ash generated by Samcheonpo and Hadong thermal power plant. The concentrations of hazardous substances contained in coal ash (bottom ash) were generally lower than criteria for contaminants in soil and standard for hazardous substances contained in designated waste. Result of column leaching test for potential environmental impact assessment indicated that increased leaching led to reduced ionic strength of coal ash. Heavy metals did not show any clear pattern of decreased concentration; however the level of heavy metals in coal ash was generally low. Ecological toxicity in the effluent from column was the level of wastewater disposal criteria (2TU) of Korea, which is judged to be not concerned level in environmental aspects.

Urbanization adjacent to rivers has increased in recent years and is considered a source of environmental contamination. The resulting increase in number of urban rivers in highly populated areas, such as the Caribbean island of Puerto Rico, has led to the appearance of synthetic as well as naturally occurring chemicals not previously observed nor regularly monitored in freshwater habitats. Some of these chemicals, such as heavy metals and plasticizers, have been shown to affect endocrine, respiratory, and nervous system function in animals and humans, even at relatively low concentrations. The purpose of this study was to measure concentrations of such emergent contaminants on rivers of urbanized areas on the northeast of Puerto Rico, as one element in the assessment of the impact of urbanism on water quality in these communities. To accomplish this, we used Inductively Coupled Plasma and Gas Chromatography Mass Spectrometry to measure amounts of heavy metals and phthalates, respectively, in superficial water of three rivers of Puerto Rico: Mameyes (non-urban), Río Piedras (urban river without a dam), and La Plata (urban river with a dam). The urban rivers had significantly higher concentrations of heavy metals arsenic, barium, cadmium, manganese, and antimony, when compared with the reference nonurban river. Manganese was the only metal found in concentrations higher than limits established by the EPA for drinking water. Of eight phthalates amenable to measurement with the chosen protocol and instrumentation, only dibutyl phthalate was detected, only in the La Plata river, and at concentrations ranging from 3 to 8 parts-per-billion. These findings suggest that urbanism close to rivers of Puerto Rico is likely having an impact on water quality and thus further study to identify the potential sources, as well as the inclusion of these emergent contaminants on the list of chemicals regularly monitored by government agencies is justified.

Peanut shells-derived activated carbons (ACPNS) with different chemical characteristics, appropriate for the removal of methomyl pesticide in aqueous solutions are prepared. The steam activated carbon is obtained from the carbonized peanut shells in the presence of nitrogen in the temperature range from 973 to 1173K. The carbonized peanut shells are, further, chemically activated using NaOH and ZnCl2. The structure of the ACPNS was characterized by N2 adsorption at 77K, scan electron microscopy and FTIR. B.E.T methods are used to deduce the effective surface areas. The parameters (such as initial pH, temperature, etc) affecting the adsorption capacity of peanut shells-derived activated carbons toward methomyl removal from aqueous solutions are investigated using batch experiments. The study of kinetic models including pseudo first order and pseudo second-order are carried out. Adsorption isotherms are investigated. Equilibrium adsorption data fitted the Langmuir adsorption isotherm well with R2> 0.9980. The maximum adsorption capacities of peanut shells-derived activated carbons for the removal of methomyl, are calculated. The thermodynamic parameters including ΔG°, ΔH° and ΔS° for the adsorption processes of methomyl on the ACPNS were calculated, and the negative value of ΔG° indicated the spontaneous nature of adsorption. The prepared peanut shells derived activated carbons are successfully applied to the removal of methomyl pesticide from different water samples with a recovery % > 95 and a RSD< 3%. The mechanism of adsorption is proposed.

Feldspar clay sample obtained from Federal Institute of Industrial Research Oshodi (FIIRO), Lagos, Nigeria was modified with Carica papaya seed to obtain CPS-modified feldspar clay Composite. The SEM of modified and unmodified samples showed irregular crystal structures. FTIR results proved the surface modification of the Feldspar at –Al–O and –Si–O centers. The CPS-modified adsorbent presented with broader peaks of inner –OH. Modification of feldspar clay sample with papaya seed decreased its PZC from pH 4.34 to 3.50 while its Specific Surface Area (SSA) was increased from 12.58 m2g−1 to 18.64 m2g−1. Modification with Carica papaya seed increased the adsorption capacity of feldspar clay from 18.26 mg/g to 45.81 mg/g for Pb (II) and 12.57 mg/g to 46.18 mg/g for Cu (II) at 308°K. Increasing temperature and initial metal ions concentration was found to increase the adsorption of both metals onto both adsorbents suggesting an endothermic adsorption reaction. The simultaneous presence of electrolyte in aqueous solution with Pb and Cu (II) was found to decrease the adsorption capacity of CPS-modified adsorbent for Pb and Cu (II). The thermodynamic calculations for the modified feldspar clay sample indicated an endothermic nature of adsorption (ΔHmean+4.38 kJ mol−1 for Pb (II) and +3.81 kJ mol−1 for Cu (II)) and an increase in entropy as a result of adsorption of Pb (II) and Cu (II) (ΔSmean−21.75 J mol−1 K for Pb (II) and −18.32 J mol−1 K for Cu (II)). The small positive values of free energy change (ΔGmean) indicated that the adsorption of Pb (II) and Cu (II) onto the modified adsorbent may require some small amount of energy to make it more feasible. Modeling equilibrium adsorption data obtained suggested that CPS-modified adsorbent sample has homogeneous adsorption sites and fit very well with Langmuir adsorption model. CPS-modified feldspar clay sample show some very good potentials as a low-cost adsorbent for the adsorption of Pb (II) and Cu (II) from aqueous solutions.

Background: The presence of gold deposits discovered in rural areas in Ghana has attracted a lot of unemployed youth and smallscale mining ventures to the rural communities. The activities of illegal small-scale gold mining (locally referred to as “galamsey”) in the community is causing serious environmental havoc and destruction. The results of heavy element profiling of gold ores associated with the underground artisanal gold mining activities of the Tongo mines in the Upper East Region of Ghana have been reported in this paper. The analysis was made to assess the occupational exposure of the miners as well as to investigate the environmental impact of toxic heavy metals. Results: Gold ores from seven artisanal gold mines were sampled and analysed for heavy elemental content using Atomic Absorption Spectroscopy technique. The ranges of major elements detected were: Pb (14.16-37.00 mg/kg); Co (6.40-31.52 mg/kg); As (25.08-27.36 mg/kg); Hg (5.04-6.16 mg/kg); Ni (69.44-332.40 mg/kg); Mn (259.04-528.64 mg/kg) and Cd were Below Detectable Limits (BDL). The potential health risk assessment calculated for a lifetime of exposure for ingestion, inhalation and dermal contact were determined as the cumulative carcinogenic risk for children and adults. Risk assessment indicated that the carcinogenic risk is completely insignificant but the cumulative non-carcinogenic Hazard Index recorded alarming values of 4.55E+00 to 4.15E+01 and 8.53E-01 to 3.43E+01 for children and adults respectively. Conclusions: The investigations show that the concentrations of Pb, As and Ni which are known carcinogens presents no significant carcinogenic lifetime risk due to ingestion, inhalation and/or dermal contact but the non-carcinogenic risk, expressed as the Hazardous Index (HI), is not so benevolent; the cumulative index for all elements exceeding 1 and should be of concern, particularly in cases of the exposure of children. Capsule abstract: The concentrations of elements ranged from 5.04 mg/kg for Hg to 528.64 for Mn with highest Hazard Index being 4.55E+00 to 4.15E+01 and 8.53E-01 to 3.43E+01 for children.