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431.
Beatrice Oneda Rosa Baldinger Regina Reissmann Irina Reshetnikova Pavel Krejci Rahim Masood Nicole Ochsenbein-Kölble Deborah Bartholdi Katharina Steindl Denise Morotti Marzia Faranda Alessandra Baumer Reza Asadollahi Pascal Joset Dunja Niedrist Christian Breymann Gundula Hebisch Margaret Hüsler René Mueller Elke Prentl Josef Wisser Roland Zimmermann Anita Rauch 《黑龙江环境通报》2014,34(6):525-533
432.
Mostafa Lamhamdi Ahmed Bakrim Noureddin Bouayad Ahmed Aarab René Lafont 《Environmental science and pollution research international》2013,20(10):7377-7385
Spinach extracts contain powerful natural antioxidants and have been used to improve the response of animal cells to various stress factors. The aim of the present study was to assess the effects of a methanolic extract of spinach (SE) used at two concentrations (21.7 and 217 ppm) on the growth, certain enzymes and antioxidant systems in wheat seedlings under lead stress. When wheat seedlings were grown for 7 days in a solution containing Pb(NO3)2 (3 mM), germination and growth were impaired, while signs of oxidative stress were observed. SE (217 ppm) pretreatment was able to protect seedlings from Pb toxicity by both reducing Pb uptake and Pb-induced oxidative stress. As a consequence, almost normal germination, elongation, biomass and α-amylase activity were restored by SE (217 ppm) pretreatment of wheat seedlings, in spite of the presence of Pb. Our results support the protective role and the antioxidant effect of SE against Pb. These results show an amazing similarity to the effects of SE in animals, which suggests that providing “nutraceuticals” to plants could improve their “health” status. 相似文献
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A Comparison of Bayesian Methods for Uncertainty Analysis in Hydraulic and Hydrodynamic Modeling 下载免费PDF全文
René A. Camacho James L. Martin William McAnally Jairo Díaz‐Ramirez Hugo Rodriguez Peter Sucsy Song Zhang 《Journal of the American Water Resources Association》2015,51(5):1372-1393
We evaluate and compare the performance of Bayesian Monte Carlo (BMC), Markov chain Monte Carlo (MCMC), and the Generalized Likelihood Uncertainty Estimation (GLUE) for uncertainty analysis in hydraulic and hydrodynamic modeling (HHM) studies. The methods are evaluated in a synthetic 1D wave routing exercise based on the diffusion wave model, and in a multidimensional hydrodynamic study based on the Environmental Fluid Dynamics Code to simulate estuarine circulation processes in Weeks Bay, Alabama. Results show that BMC and MCMC provide similar estimates of uncertainty. The posterior parameter densities computed by both methods are highly consistent, as well as the calibrated parameter estimates and uncertainty bounds. Although some studies suggest that MCMC is more efficient than BMC, our results did not show a clear difference between the performance of the two methods. This seems to be due to the low number of model parameters typically involved in HHM studies, and the use of the same likelihood function. In fact, for these studies, the implementation of BMC results simpler and provides similar results to MCMC. The results of GLUE are, on the other hand, less consistent to the results of BMC and MCMC in both applications. The posterior probability densities tend to be flat and similar to the uniform priors, which can result in calibrated parameter estimates centered in the parametric space. 相似文献
435.
为了阐明反复扰动下,不同初始浓度藻对沉积物中各形态磷释放的影响.以太湖梅梁湾沉积物和上覆水作为研究材料,探讨了扰动和藻类共同作用下沉积物中各形态磷的变化规律.结果表明,无扰动状态下,NH4Cl-P和Res-P均有所降低,而Fe/Al-P和Ca-P则有所增加.其中,Ca-P随藻类初始浓度增加而增加,分别增加48%、66%、74%.但是,扰动状态下,NH4Cl-P和Res-P也明显降低.Fe/Al-P明显增加,其占总磷的百分比为66.2%(3组试验的平均值)高于不扰动状态(53.4%,3组试验的平均值);此外,Ca-P占总磷的百分比为24.1%(3组扰动试验的平均值)明显低于不扰动状态(33.0%,3组试验的平均值).这暗示了扰动和藻类共同作用下促进了Fe/Al-P的形成,而无扰动下藻类却促进了Ca-P的形成. 相似文献
436.
短链氯化石蜡(short-chain chlorinated paraffins,SCCPs)是一组成分复杂的氯代正构烷烃,在环境中普遍存在。然而有关其毒性机理的信息十分有限,限制了对其健康风险的评估。本研究采用液相色谱–串联质谱(LC-MS/MS)分析技术,研究了不同剂量的SCCPs暴露(0、1.0、10.0和100.0μg·L-1;C13-CPs;55.0%Cl)对人体肝癌细胞Hep G2的糖代谢、氨基酸代谢和脂肪酸代谢的影响。通过偏最小二乘判别分析(PLS-DA)鉴别各组代谢产物谱差异,发现3个SCCPs暴露剂量组均能够与对照组完全分开,表明SCCPs短期暴露能够引起细胞代谢活动的显著改变。SCCPs的低剂量暴露可明显刺激Hep G2细胞对氨基酸的吸收。与对照组相比,SCCPs低剂量暴露组(1.0μg·L-1)培养基中谷氨酰胺、色氨酸和丝氨酸的含量显著(P0.05)降低。而高剂量SCCPs(100.0μg·L-1)暴露抑制了细胞对氨基酸和葡萄糖吸收,但促进了乳酸、丙氨酸、半胱氨酸的生成。氨基酸吸收的抑制不可避免地会影响蛋白质的合成。同时,SCCPs的暴露使饱和脂肪酸代谢紊乱,使不饱和脂肪酸水平上调。为确定SCCPs的毒性作用方式,有必要从转录组和蛋白组层面进一步研究其毒性机制。 相似文献
437.
Junxia Li Zipeng Dong Yiyu Li Junmei Yang Xingang Liu Liang Yuan Yan Yin Zhanqing Li Peiren Li Gang Ren Lijun Jin Runjun Li 《环境科学学报(英文版)》2015,27(8):44-56
Vertical distributions of aerosol optical properties based on aircraft measurements over the Loess Plateau were measured for the first time during a summertime aircraft campaign, 2013 in Shanxi, China. Data from four flights were analyzed. The vertical distributions of aerosol optical properties including aerosol scattering coefficients (σsc), absorption coefficients (σab), Angström exponent (α), single scattering albedo (ω), backscattering ratio (βsc), aerosol mass scattering proficiency (Qsc) and aerosol surface scattering proficiency (Qsc′) were obtained. The mean statistical values of σsc were 77.45 Mm− 1 (at 450 nm), 50.72 Mm− 1 (at 550 nm), and 32.02 Mm− 1 (at 700 nm). The mean value of σab was 7.62 Mm− 1 (at 550 nm). The mean values of α, βsc and ω were 1.93, 0.15, and 0.91, respectively. Aerosol concentration decreased with altitude. Most effective diameters (ED) of aerosols were less than 0.8 μm. The vertical profiles of σsc,, α, βsc, Qsc and Qsc′ showed that the aerosol scattering properties at lower levels contributed the most to the total aerosol radiative forcing. Both α and βsc had relatively large values, suggesting that most aerosols in the observational region were small particles. The mean values of σsc, α, βsc, Qsc, Qsc′, σab and ω at different height ranges showed that most of the parameters decreased with altitude. The forty-eight hour backward trajectories of air masses during the observation days indicated that the majority of aerosols in the lower level contributed the most to the total aerosol loading, and most of these particles originated from local or regional pollution emissions. 相似文献
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439.
Assessment of potential soybean cadmium excluder cultivars at different concentrations of Cd in soils 总被引:2,自引:0,他引:2
The selection of cadmium-excluding cultivars has been used to minimize the transfer of cadmium into the human food chain. In this experiment, five Chinese soybean plants were grown in three soils with different concentrations of Cd (0.15, 0.75 and 1.12 mg/kg). Variations in uptake, enrichment, and translocation of Cd among these soybean cultivars were studied. The results indicated that the concentration of Cd in seeds that grew at 1.12 mg/kg Cd in soils exceeded the permitted maximum levels in soybeans. Therefore, our results indicated that even some soybean cultivars grown on soils with permitted levels of Cd might accumulate higher concentrations of Cd in seeds that are hazardous to human health. The seeds of these five cultivars were further assessed for interactions between Cd and other mineral nutrient elements such as Ca, Cu, Fe, Mg, Mn and Zn. High Cd concentration in soil was found to inhibit the uptake of Mn. Furthermore, Fe and Zn accumulations were found to be enhanced in the seeds of all of the five soybean cultivars in response to high Cd concentration. Cultivar Tiefeng 31 was found to fit the criteria for a Cd-excluding cultivar under different concentrations of Cd in soils. 相似文献
440.