Atrazine distribution measured in soil and leachate following infiltration conditions

Atrazine transport through packed 10 cm soil columns representative of the 0-10 cm soil horizon was observed by measuring the atrazine recovery in the total leachate volume, and upper and lower soil layers following infiltration of 7.5 cm water using a mechanical vacuum extractor (MVE). Measured recoveries were analyzed to understand the influence of infiltration rate and delay time on atrazine transport and distribution in the column. Four time periods (0.28, 0.8, 1.8, and 5.5 h) representing very high to moderate infiltration rates (26.8, 9.4, 4.2, and 1.4 cm/h) were used. Replicate soil columns were tested immediately and following a 2-d delay after atrazine application. Results indicate atrazine recovery in leachate was independent of infiltration rate, but significantly lower for infiltration following a 2-d delay. Atrazine distribution in the 0-1 and 9-10 cm soil layers was affected by both infiltration rate and delay. These results are in contrast with previous field and laboratory studies that suggest that atrazine recovery in the leachate increases with increasing infiltration rate. It appears that the difference in atrazine recovery measured using the MVE and other leaching experiments using intact soil cores from this field site and the rain simulation equipment probably illustrates the effect of infiltrating water interacting with the atrazine present on the soil surface. This work suggests that atrazine mobilization from the soil surface is also dependent on interactions of the infiltrating water with the soil surface, in addition to the rate of infiltration through the surface soil.     

Modeling aerosol formation in opposed-flow diffusion flames

The microstructures of atmospheric pressure, counter-flow, sooting, flat, laminar ethylene diffusion flames have been studied numerically by using a new kinetic model developed for hydrocarbon oxidation and pyrolysis. Modeling results are in reasonable agreement with experimental data in terms of concentration profiles of stable species and gas-phase aromatic compounds. Modeling results are used to analyze the controlling steps of aromatic formation and soot growth in counter-flow configurations. The formation of high molecular mass aromatics in diffusion controlled conditions is restricted to a narrow area close to the flame front where these species reach a molecular weight of about 1000 u. Depending on the flame configuration, soot formation is controlled by the coagulation of nanoparticles or by the addition of PAH to soot nuclei.     

Assessment of the effect of welding fumes on welders’ cognitive failure and health-related quality of life

Introduction. This study examined whether cognitive symptoms and health-related quality of life can be affected by welding fume exposure. Method. Participants consisted of welders (n?=?40) and welder assistants (n?=?25) from welding units as the exposed group, and office workers (n?=?44) as the non-exposed group. All participants were studied using ambient air monitoring and two types of questionnaires: the Cognitive Failures Questionnaire (CFQ) and the 36-item Short Form Health Survey (SF-36). Results. Welders and welder assistants were exposed to higher concentrations of all airborne metals than office employees, except for aluminum and chromium (p?p?M (SD)?=?54.84 (17.88)). The relationships between total CFQ score and the measured concentration of nickel at peak work rate was significant for welders. Conclusion. Cognitive symptoms and health-related quality of life were not related to the measures of welding fume exposure and further research should be performed to find other influencing factors.     

Phenol removal from aqueous environments by natural & chemically modified kaolin clay

Natural, acid and base modified kaolin clays were studied for the sake of phenol and 4-chlorophenol removal from aqueous environments and their application to real ground and industrial wastewater samples. Scanning electron microscope (SEM), infrared spectroscopy (IR), X-ray diffraction (XRD), Thermo Gravimetric Analysis (TGA), Differential Thermal Analysis (DTA), and Surface area analysis were employed for characterization of the adsorbents microstructure. Operating factors such as adsorbent dose, solution pH, initial phenol concentration, and contact time were studied. The experimental data displayed that the increase of the adsorbent dose, contact time, and pH value from 2 to 7 increases the efficiency of the removal process. Optimal conditions for phenolic removal were; contact time of 300 min, primary phenol solution of 25 mg/L, pH 7 and 2.5 g/L as an appropriate adsorbent dose using crude (natural), acid modified and base modified kaolin clays. The higher phenolic removal efficiencies were obtained at 5 mg/L as 90, 97, 96.2%, respectively, for the adsorbents in the previously mentioned order. The adsorption capacity in the removal of phenol and 4-chlorophenol were 7.481 and 4.195, 8.2942 and 3.211, and 8.05185 and 18.565 mg/g, respectively, for the adsorbents in the same mentioned order. The adsorption equilibrium data were fitted and analyzed with four isotherm models, namely, Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherm equations. The adsorption process of phenol on studied adsorbents was exothermic, spontaneous and thermodynamically favorable proved by the negative values of their thermodynamic parameters ΔH° and ΔG°. The correlation coefficient (R²) for all concentrations was higher than 0.94, which indicates that in the studied system, the data suitably fit the first-order kinetics. The % desorption capacity was amounted to 96%, 91.11%, and 87.06% of adsorbed phenol, respectively, for the adsorbents in the previous order using 0.1N NaOH and 10% V/V ethanol solutions as eluents at 25°C, indicating the reusability of the adsorbents. Kaolin and its modified forms can be introduced as eco-friendly and low-cost adsorbents in water remediation implementation.     

A comparative study of trace metals in male and female Caspian kutum (<Emphasis Type="Italic">Rutilus frisii kutum</Emphasis>) from the southern basin of Caspian Sea

This study focuses on the extent of zinc (Zn), copper (Cu), cadmium (Cd), cobalt (Co), manganese (Mn), lead (Pb), mercury (Hg), and arsenic (As) bioaccumulation in edible muscles of Caspian kutum (Rutilus frisii kutum), in both male and female sexes at Noor and Babolsar coastal regions from the southern basin of Caspian Sea. These values were compared with the WHO and the UNFAO safety standards regarding the amount of the abovementioned heavy metals in fish tissues (mg/kg ww). Results showed that the accumulation of these elements (except for Zn) was not significantly different between sexes of male and female in Babolsar coastal regions (P?>?0.05). In the other hand, accumulation of Hg and As at edible muscles of Caspian kutum has significant difference between two sexes of male and female in Noor coastal regions (P?<?0.05), the female had higher concentration than the male. Furthermore, it was not significantly correlated with sex and rivers in length and weight of fish (R ²?<?0.50; P?>?0.05). Based on the results, the concentration of heavy metals in the studied fish tissues proved to be significantly lower than international standards (P?<?0.05), so its consumption is not a threat to the health of consumers.     

Prophylactic effects of Cynara scolymus L. leaf and flower hydroethanolic extracts against diethylnitrosamine/acetylaminoflourene-induced lung cancer in Wistar rats

Environmental Science and Pollution Research - The study examines the prophylactic action of artichoke leaf hydroethanolic extract (ALE) and artichoke flower head hydroethanolic extract (AFE)...     

Green synthesis of recyclable iron oxide nanoparticles using Spirulina platensis microalgae for adsorptive removal of cationic and anionic dyes

Environmental Science and Pollution Research - Globally, organic dyes are major constituents in wastewater effluents due to their large-scale industrial applications. These persistent pollutants...     

MANAGING GROUND WATER QUALITY IN RELATION TO AGRICULTURAL ACTiVITIES1

ABSTRACT: Ground water quality is an environmental issue of national concern. Agricultural activities, because they involve large land areas, often are cited as a major contributor of ground water contaminants. It appears that some degree of ground water contamination from agricultural land use is inevitable, especially where precipitation exceeds evapotranspiration. For this reason, and because agriculture differs significantly from point sources of pollution, farmers, policymakers, and scientists need alternative management strategies by which to protect ground water. Mathematical models coupled to geographic information systems to form expert systems can be important management tools for both policymakers and agricultural producers. An expert system can provide farmers, researchers, and environmental managers with information by which to better manage agricultural production systems to minimize ground water contamination. Significant research is necessary to perfect such a system, necessitating interim ground water management strategies that include not only a strong research program, but educational and public policy components as well.