Toxicologie environnementale et analytique

A mathematical model of heat balance was developed to predict the compost temperature during the maturation stage. The components of the energy balance of the compost pile which include: heat gained (heat generation and solar radiation) and heat lost (radiation, evaporation, convection, and conduction) at different ambient temperatures. The model was able to predict the pile temperature at different ambient temperatures (15, 20, 25, 30 and 35°C) and different airflow rates (0.7, 1.1 and 1.5 mg air s-1 kg-1 dry matter). The results showed that the pile temperature increases with increasing ambient temperature and it decreases with increasing airflow rates, where, as the ambient temperature increased from 15 to 35°C, the pile temperature increased from 33.40 to 37.41°C, and when the airflow rates increased from 0.7 to 1.5 mg air s-1 kg-1 dry matter, the pile temperature decreased from 34.40 to 32.39°C. The pile temperature increased slightly and reached a maximum value at day 14. It indicates that the net energy gained to the pile increases with increasing ambient temperature, meanwhile, the heat lost decreases with increasing ambient temperature. The model results indicated that the predicted daily temperature was in a reasonable agreement with those measured ones and other data in literature (Barrena et al. and Ahn et al.) at different ambient temperatures and airflow rates, where, it ranged from 30.30 to 73.40°C, while it was from 18.0 to 71.0°C experimentally during the whole period of compost maturation.

The study was conducted to estimate total mercury in water and sediment of Bidyadhari river of Indian Sundarban delta in pre-monsoon, monsoon and post-monsoon period. Bidyadhari river presently serves as a sewage and excess rainwater outlet from the Kolkata metropolitan and adjacent area which ultimately empties at the Bay of Bengal in the course of the Indian Sundarban delta. Four different study sites situated around the course of the river were selected from the outfall of sewage canals at Kulti-Ghushighata (S1) where metropolitan sewages discharged and mixed up into water of Bidyadhari river which ultimately carried through this river via stations Malancha (S2), Kanmari (S3) to Dhamakhali (S4), just before the river confluences with the larger Raimangal river at northern Sundarban delta. Mean mercury concentration in collected water ranged BDL to 0.014 ± 0.001 μg ml-1 and sediment samples ranged BDL to 0.260 ± 0.014 μg g-1. Highest mercury accumulations in river water both high tide and low tide was found at S4 followed by S3 with pronounced seasonal variation. Mercury present in the sediment (0-5 cm) showed a remarkable site and season specific differences with highest concentration in S4. Box whisker plot revealed that one extreme value was found at the S4 along with one outlier was at S3 and five outliers were at S4 during monsoon period. Regarding total mercury assemblages, PCA analysis showed all the sites except S4 are significantly associated. Based on Effective Range Low (ERL) value it is considered that sediment is still low mercury enrichment with less ecotoxicological risk while level often above the requirement desirable limit of drinking water recommended by WHO.

The presence of synthetic dyes is often underestimated in environmental protection. However, it has been demonstrated the impact of colored compounds in ecology and human health. Green tea (GT) and peppermint (PM) tea bag wastes were used as potential adsorbents of dyes from aqueous solutions to evaluate the effect of pH on the adsorption. Basic yellow 57, basic blue 99 and crystal violet were chosen as model dyes due to their widespread use in the industry. Dye solutions at different pH values were placed in contact with the adsorbents in batch experiments at room temperature. Results indicate that crystal violet is totally removed from the solution by the adsorbents (100% removal), followed basic blue 99 and basic yellow. PM reports the highest dye removal. Our data was compared to recently published reports, indicating their potential applicability to real wastewaters, as it is optimum at neutral pH values. These results demonstrate that these materials are excellent and cost-effective candidates for the removal of dye pollutants from contaminated solutions.

Our study was aimed to evaluate the effects of cadmium on chick embryo liver tissue. 10th, 11th and 12th day old Bobcock strain chick embryos were exposed to cadmium individually, by in ovo treatment. These concentrations 40, 50, 60 μg of Cadmium at different time intervals i.e., 24, 48, 72 hr, were administered to developing chick embryo. On the 13th study day, blood and the liver tissues collected were tested for genotoxic and lipid peroxidation assays. In this study, the presence of micronucleated erythrocytes and also various abnormal cells in the blood smear indicated the role of cadmium-induced genotoxicity. Current findings showed that frequency of micronucleated erythrocytes increased with increased doses of cadmium and time interval. MDA levels were high in cadmium exposed group compared to control group. These findings suggest the genotoxic and an oxidative stress mechanism in cadmium-induced liver tissue enhances damage.

Topographic and climatic conditions of major parts of Khyber Pakhtunkhwa warrant special measures for management of natural resources to prevent degradation of land resources, conservation of forest related natural resources, optimization of resource use, provision of sustainable livelihood and alleviation of poverty. National rate of deforestation is around 7000 to 9000 hectares per annum in Khyber Paktunkhwa. Destruction of forests is more evident in certain areas of Khyber Pakhtunkhwa. To reverse this trend and to conserve natural resources, participatory approach has been suggested as an instrument at several national and international forums. The linchpin in the participatory approach is formation and mobilization of Village Development Committees (VDCs). These committees were formulated under Malakand Social Forestry Project. It was assessed through this research how much instrumental have been VDCs to mobilize communities. Results show there is some partial success. Still a lot is needed to improve the working of VDCs.

Background concentrations of heavy metal ions concentration in soils are important due to their pollution potential and toxic effect of these elements on human health and the environment. These metals in soils in the vicinity of paper manufacturing industry were studied. Concentrations of these heavy metal ions (e.g., Pb, Zn, Cd,Cr) were analyzed using Atomic Absorption Spectrophotometer (A.A.S). The findings revealed that the average concentrations of these metals in soil samples were three to ten times higher than the permissible limits. Levels of these trace metals in the industrial environment were generally high, indicating that the activities of paper industry and associated processes contributed to the observed higher levels of trace metals in the industry environment. The aim of this study was to determine the levels of these heavy metals in the soil and to ascertain the pollution status.

From June 2009 to August 2011, an integrated physical and ecological engineering experiment (PEE) for ecological remediation was conducted in the Maixi river estuary in Baihua Reservoir. An experiment site (EXP) inside, and a reference site (REF) outside, the engineering enclosure were selected. Total nitrogen (TN), total phosphorus (TP), Chlorophyll-a (Chl-a), and chemical oxygen demand (COD) at EXP were significantly lower than at REF; and the greatest differences were 1.00 mg/L, 0.04 mg/L, 23.06 μg/L, and 8.40 mg/L, respectively. Transparency at EXP was dramatically higher than at REF. The trophic index state (TSI) was between oligotrophic and mesotrophic at EXP, between mesotrophic and eutrophic at REF. Phytoplankton abundance in June 2011 was 2100×104 cells/L at REF, but lower at EXP with 33×104 cells/L. Cyanobacteria dominated phytoplankton biomass at both sites, but a higher proportion of diatoms and dinoflagellates was found at EXP. Rotifers were the main estuarine zooplankton. Copepod abundance was significantly different among the sites (p<0.01), with greater abundance at EXP. In general, eutrophication was controlled by the PEE, which could be adjusted to improve water quality.

The study aimed at chemical and mineralogical characterization of whole particulate matter (PM) in the vicinity of a mining phosphate basin at urban area in Gafsa. Heavy metals concentrations in PM samples (Cd, Fe, Cu, Mn, Cr, Zn, Ni, Al, Pb), MgO and SiO2 were determined by atomic absorption spectrometry. Calcium and phosphorus oxides (CaO, P2O5) were analyzed by Technicon Auto-analyzer. Potassium and sodium oxides (K2O, Na2O) were analyzed by flame photometer. Ionic species (S04 2-, Cl-, NO3 -) were quantified by ion chromatography while organic carbon (OC) content was determined using carbon sulfur Analyzer. The mineral phase identified by X-Ray powder diffraction technique and SEM-EDX provides information about morphology and chemical composition of PM. As regards the chemical characterization it was found that samples were enriched predominantly in SiO2, CaO and P2O5 which were detected only at mining area (S2 and S3) Weak concentrations of K2O, Na2O and MgO were also found. In addition the minerals phases identified in the samples were carbonate fluorapatite, Calcite, Heulandite, Gypsum and Dolomite. The values of ionic composition were in the flowing order SO4 2->Cl->NO3 -. Results also showed that heavy metals pollution increased by the proximity to the mining area. SEM-EDX revealed that particles are almost spherical.

The application of nanoparticle technology is rapidly expanding. The reduced dimensionality of nanoparticles can give rise to changes in chemical and physical properties, often resulting in altered toxicity. People are exposed dermally to titanium dioxide (TiO2) nanoparticles in industrial and residential settings. The general public is increasingly exposed to these nanoparticles as their use in cosmetics, sunscreens and lotions expands. The toxicity of TiO2 nanoparticles towards human skin cells is unclear and understudied. We used a human skin fibroblast cell line to investigate the cytotoxicity and clastogenicity of TiO2 nanoparticles after 24 h exposure. In a clonogenic survival assay, treatments of 10, 50 and 100 μg/cm2 induced 97.8, 88.8 and 84.7% relative survival, respectively. Clastogenicity was assessed using a chromosomal aberration assay in order to determine whether TiO2 nanoparticles induced serious forms of DNA damage such as chromatid breaks, isochromatid lesions or chromatid exchanges. Treatments of 0, 10, 50 and 100 μg/cm2 induced 3.3, 3.0, 3.0 and 2.7% metaphases with damage, respectively. No isochromatid lesions or chromatid exchanges were detected. These data show that TiO2 nanoparticles are not cytotoxic or clastogenic to human skin cells.