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411.
Nicoleta A. Suciu Ettore Capri 《Journal of environmental science and health. Part. B》2013,48(6):525-532
Sorption of three pesticides (chlorpyrifos, metalaxyl and penconazole) has been measured on a commercial clay montmorillonite and on the same mineral modified with either of two cationic-surfactant micelles. Both micelle–clay complexes, commercial names Cloisite 20A and Cloisite 30B, showed a good capacity to sorb all three pesticides from water, whereas their sorption on the natural montmorillonite was not described by an isotherm. Modelling sorption on both micelle–clay complexes showed that the Freundlich sorption constant (K F) was higher for chlorpyrifos on Cloisite 20A (K F = 7.76) than on Cloisite 30B (K F = 5.91), whereas the sorption of metalaxyl was stronger on Cloisite 30B (K F = 1.07) than on Cloisite 20A (K F = 0.57). Moreover the micelle–clay complex Cloisite 20A also showed a good affinity for penconazole, the maximum quantity adsorbed (q m) of 6.33 mg g?1 being 45% more than that on Cloisite 30B. Single-batch adsorption of each pesticide onto both micelle–clay complexes was studied using the Freundlich isotherm for chlorpyrifos and metalaxyl and the Langmuir isotherm for penconazole. The Cloisite 20A micelle–clay complex was predicted to require 23% less adsorbent to treat certain volumes of wastewater containing 30 mg L?1 chlorpyrifos, 43% more to treat metalaxyl similarly and 57% less to treat penconazole compared with Cloisite 30B. 相似文献
412.
Ramazan Bal Gaffari Türk Mehmet Tuzcu Okkes Yilmaz Tuncay Kuloglu Ramazan Gundogdu 《Journal of environmental science and health. Part. B》2013,48(5):434-444
In the current study it was aimed to investigate the toxicity of low doses of imidacloprid (IMI) on the reproductive organ systems of adult male rats. The treatment groups received 0.5 (IMI-0.5), 2 (IMI-2) or 8 mg IMI/kg body weight by oral gavage (IMI-8) for three months. The deterioration in sperm motility in IMI-8 group and epidydimal sperm concentration in IMI-2 and IMI-8 groups and abnormality in sperm morphology in IMI-8 were significant. The levels of testosterone (T) and GSH decreased significantly in group IMI-8 compared to the control group. Upon treatment with IMI, apoptotic index increased significantly only in germ cells of the seminiferous tubules of IMI-8 group when compared to control. Fragmentation was striking in the seminal DNA from the IMI-8 group, but it was much less obvious in the IMI-2 one. IMI exposure resulted in elevation of all fatty acids analyzed, but the increases were significant only in stearic, oleic, linoleic and arachidonic acids. The ratios of 20:4/20:3 and 20:4/18:2 were decreased and 16:1n-9/16:0 ratio was increased. In conclusion, the present animal experiments revealed that the treatment with IMI at NOAEL dose-levels caused deterioration in sperm parameters, decreased T level, increased apoptosis of germ cells, seminal DNA fragmentation, the depletion of antioxidants and change in disturbance of fatty acid composition. All these changes indicate the suppression of testicular function. 相似文献
413.
Mahrous M. Kandil Ahmed F. El-Aswad William C. Koskinen 《Journal of environmental science and health. Part. B》2013,48(7):473-483
Sorption–desorption of the insecticide imidacloprid 1-[(6-chloro-3-pyridinyl)-methyl]-N-nitro-2-imidazolidinimine onto a lacustrine sandy clay loam Egyptian soil and its clay and humic acid (HA) fractions was investigated in 24-h batch equilibrium experiments. Imidacloprid (IMDA) sorption–desorption isotherms onto the three sorbents were found to belong to a non-linear L-type and were best described by the Freundlich model. The value of the IMDA adsorption distribution coefficient, Kdads, varied according to its initial concentration and was ranged 40–84 for HA, 14–58 for clay and 1.85–4.15 for bulk soil. Freundlich sorption coefficient, Kfads, values were 63.0, 39.7 and 4.0 for HA, clay and bulk soil, respectively. The normalized soil Koc value for imidacloprid sorption was ~800 indicating its slight mobility in soils. Nonlinear sorption isotherms were indicated by 1/nads values <1 for all sorbents. Values of the hysteresis index (H) were <1, indicating the irreversibility of imidacloprid sorption process with all tested sorbents. Gibbs free energy (ΔG) values indicated a spontaneous and physicosorption process for IMDA and a more favorable sorption to HA than clay and soil. In conclusion, although the humic acid fraction showed the highest capacity and affinity for imidacloprid sorption, the clay fraction contributed to approximately 95% of soil-sorbed insecticide. Clay and humic acid fractions were found to be the major two factors controlling IMDA sorption in soils. The slight mobility of IMDA in soils and the hysteresis phenomenon associated with the irreversibility of its sorption onto, mainly, clay and organic matter of soils make its leachability unlikely to occur. 相似文献
414.
James Burdon Michael H.B. Hayes Malcolm E. Pick 《Journal of environmental science and health. Part. B》2013,48(1):37-51
Abstract Charge distributions in 1, 1'‐ethylene‐2, 2'‐bipyridylium (diquat), 1,1'‐dimethyl‐4,4'‐bipyridylium (paraquat) and 1‐methylpyridinium organocations were calculated by a Complete Neglect of Differential Overlap semi‐empirical quantum mechanical procedure. The data show that the positive charges in the organocations are distributed around the molecules and are greatest in the positions ortho and para to the heterocyclic nitrogen atoms. Earlier interpretations of the mechanisms of adsorption of paraquat and diquat by soils and clays assumed that the charges were located in the heterocyclic nitrogen atoms. Here some consideration is given to the influence of the charge delocalizations on the processes of adsorption by montmorillonite and vermiculite clay preparations. 相似文献
415.
采用压汞法(MIP)和扫描电镜(SEM)法,在自由和侧限状态下,试验研究了高压实新疆阿尔泰膨润土在不同吸力条件下的微观结构变化特征。吸力的控制采用了气相法和渗析(液相)法。研究结果表明:(1)低吸力范围内,自由膨胀和侧限条件下的高压实膨润土土水特征存在明显差异;(2)膨润土在自由和侧限状态下的水化过程中呈现出了截然不同的微结构变化特征。自由膨胀条件下,土的吸水膨胀量主要来自土中大孔隙的逐渐膨胀。侧限状态下,随着控制吸力的降低,膨润土的大孔隙逐渐被压缩,较小孔隙的数量不断增加,土中孔隙分布变得更加均匀。 相似文献
416.
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418.
419.
邢国军 《中国环境管理干部学院学报》2012,(1):7-9,32
对开展排污权交易的目的、意义、关键因素进行了分析,对唐山排污权交易的工作进程以及交易指标、交易主体、交易程序、指导价格、申购数量、交易范围、优先及限制条件等模式特点进行了阐述,以期为同类型城市开展排污权交易提供参考。 相似文献
420.
Shalamu Abudu J. Phillip King Zhuping Sheng 《Journal of the American Water Resources Association》2012,48(1):10-23
Abudu, S., J.P. King, Z. Sheng, 2011. Comparison of the Performance of Statistical Models in Forecasting Monthly Total Dissolved Solids in the Rio Grande. Journal of the American Water Resources Association (JAWRA) 48(1): 10‐23. DOI: 10.1111/j.1752‐1688.2011.00587.x Abstract: This paper presents the application of autoregressive integrated moving average (ARIMA), transfer function‐noise (TFN), and artificial neural networks (ANNs) modeling approaches in forecasting monthly total dissolved solids (TDS) of water in the Rio Grande at El Paso, Texas. Predictability analysis was performed between the precipitation, temperature, streamflow rates at the site, releases from upstream reservoirs, and monthly TDS using cross‐correlation statistical tests. The chi‐square test results indicated that the average monthly temperature and precipitation did not show significant predictability on monthly TDS series. The performances of one‐ to three‐month‐ahead model forecasts for the testing period of 1984‐1994 showed that the TFN model that incorporated the streamflow rates at the site and Caballo Reservoir release improved monthly TDS forecasts slightly better than the ARIMA models. Except for one‐month‐ahead forecasts, the ANN models using the streamflow rates at the site as inputs resulted in no significant improvements over the TFN models at two‐month‐ahead and three‐month‐ahead forecasts. For three‐month‐ahead forecasts, the simple ARIMA showed similar performance compared to all other models. The results of this study suggested that simple deseasonalized ARIMA models could be used in one‐ to three‐month‐ahead TDS forecasting at the study site with a simple, explicit model structure and similar model performance as the TFN and ANN models for better water management in the Basin. 相似文献