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251.
Vassilios Triantafyllidis Dimitra Hela Maria Papadaki Dimitrios Bilalis Ioannis Konstantinou 《Water, air, and soil pollution》2012,223(4):1625-1637
The soil mobility and dissipation of two pesticides with different physicochemical properties, namely mefenoxam, a systemic
fungicide, and pendimethalin a selective herbicide, were determined in bare and tobacco tilled soil columns, which were installed
in field conditions for over 125 days. Soil samples were collected at specific time intervals for a 125-day period and the
rate of pesticide dissipation and leaching through the soil column was studied. The dissipation half-lives of mefenoxam from
the top soil layer in tilled and bare soil columns were estimated at 10.3 and 13.1 days, respectively, while the corresponding
half-lives for pendimethalin were 26.7 and 27.5 days, respectively. The dissipation of mefenoxam and pendimethalin from the
top soil in tobacco cultivation was faster in comparison with bare soil; however, 120 days after their application, both pesticide
residues were detected in the soil. Maximum concentrations of mefenoxam and pendimethalin were observed on the 15th and 33rd day, respectively, in the soil layer of 5–10 cm depth and on the 30th day and 63rd day, respectively, in the soil layer of 10–15 cm depth. Higher concentrations were observed in bare soil columns. The leaching
of both pesticides was simulated with the continuous stirred tank reactor (CSTR) in series model. The simulated peak concentration
and peak time for both pesticides fitted reasonably well to the experimental values. 相似文献
252.
Irakli MN Samanidou VF Papadoyannis IN 《Journal of agricultural and food chemistry》2012,60(9):2076-2082
The separation and determination of tocopherols (Ts) and tocotrienols (T3s) by reversed-phase high-performance liquid chromatography with fluorescence detection has been developed and validated after optimization of various chromatographic conditions and other experimental parameters. Analytes were separated on a PerfectSil Target ODS-3 (250 × 4.6 mm, 3 μm) column filled with a novel sorbent material of ultrapure silica gel. The separation of Ts and T3s was optimized in terms of mobile-phase composition and column temperature on the basis of the best compromise among efficiency, resolution, and analysis time. Using a gradient elution of mobile phase composed of isopropanol/water and 7 °C column temperature, a satisfactory resolution was achieved within 62 min. For the quantitative determination, α-T acetate (50 μg/mL) was used as the internal standard. Detection limits ranged from 0.27 μg/mL (γ-T) to 0.76 μg/mL (γ-T3). The validation of the method was examined performing intraday (n = 5) and interday (n = 3) assays and was found to be satisfactory, with high accuracy and precision results. Solid-phase extraction provided high relative extraction recoveries from cereal samples: 87.0% for γ-T3 and 115.5% for δ-T. The method was successfully applied to cereals, such as durum wheat, bread wheat, rice, barley, oat, rye, and corn. 相似文献
253.
Air pollutants emissions from traffic are very closely connected to urban air quality, in a local scale, as well as to global
problems like climate change, in a large scale. Road transport air pollutants emissions represent, in most cases, a critical
parameter for a comprehensive and successful understanding of the mechanisms governing the air pollutants concentrations.
Hence, reliable estimations and comprehension of road transport emissions are indispensable in order to set reliable strategies
in the direction of air pollution abatement and management of air pollutants and greenhouse gases emissions. In this framework,
in the present work, the emissions of air pollutants from road transport in Greece will be presented for the whole period
1990–2009 as it was found that a detailed, accurate and reliable emissions inventory was missing. The whole period emissions
variation has clarified the impact of the change in the vehicle fleet, the engine technologies and the fuel quality. The calculated
results have revealed that the age of the vehicles and the corresponding engine technology are the critical parameters determining
the amount of the pollutants emitted. This was mainly observed in both passenger cars and heavy duty vehicles demonstrating
the importance of a renewal programme of the old circulating vehicles in order to set an effective air pollution abatement
strategy. Passenger cars were found to be responsible for the major part of most air pollutants emissions except from nitrogen
oxides and particulates emissions. Heavy duty vehicles contribute more than 66% to nitrogen oxides and particulates emissions.
For the whole time period, all calculated pollutants present a decreasing trend, with the exception of carbon dioxide and
nitrous oxide which increase constantly, ranging from −96% for sulphur dioxide to −1% for PM10. 相似文献
254.