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981.
X. Gu T. Cheng D. Xie Z. Li T. Yu H. Chen 《Atmospheric environment (Oxford, England : 1994)》2011,45(36):6607-6612
A precise estimate of polarization induced by surface is crucial for polarized remote sensing dedicated to monitoring aerosol properties over urban area. The accurate knowledge of interaction between surface and aerosol polarized reflectance is essential for accurately achieving aerosol properties. In order to study surface and aerosol polarized reflectance for aerosol retrievals over urban area, a new airborne directional polarimetric camera (DPC) with high spatial resolution (4 m at 4000 m a.g.l) was developed. The surface polarized reflectance over distinct surface covers of urban area (forest, shrub, and soil) were studied using DPC measurements during a field campaign in the Pearl River Delta (PRD), China. The large variations were found in surface polarized reflectance of distinct urban covers due to surface type variability. For all surface types, the empirical BPDF model cannot describe accurately surface polarized reflectance at all possible illumination and observation geometries. From the quantitatively study of relationship between surface and aerosol polarized contribution to DPC measurements, we show that the polarized contributions of aerosol, which optical properties were defined by ground-based measurements, are much larger than the polarized contribution of surface, and found that the polarized contribution of surface covers increases with decreasing NDVI. The effect of polarization accuracy of measurements on aerosol retrieval was also investigated using DPC measurements, and found that 0.1% polarization accuracy of measurements can be neglected when AOD is retrieved using polarized measurements. Based on the information of effects of polarized reflectance differences between distinct surface covers and polarization accuracy of polarized measurements on retrieved aerosols over urban area, we found that the accuracy of aerosol retrieval over forest covers is higher than other surface types using polarized remote sensing. 相似文献
982.
983.
臭氧降解选矿药剂丁基黄药的实验研究 总被引:3,自引:2,他引:1
采用臭氧氧化去除水中的丁基黄药,研究了臭氧氧化丁基黄药的影响因素,考察了反应溶液的初始pH值、臭氧投加量、反应物初始浓度、自由基抑制剂对丁基黄药降解率的影响。结果表明,pH值、臭氧投加量越高,丁基黄药降解率越高,随着丁基黄药初始浓度的升高,丁基黄药的去除效率会下降,但绝对去除量会升高。碳酸氢根和叔丁醇能在一定程度上降低丁基黄药的降解效率。同时讨论了体系中COD、TOC、UV254、pH和电导率的变化情况,结果表明臭氧氧化很难将体系中的COD和TOC大幅度降低,反应体系pH随氧化时间的增加而降低的,GC—MS分析表明,丁基黄药氧化的臭氧化产物为醇类和羧酸类物质。 相似文献
984.
Cu fractions, mobility and bioavailability in soil-wheat system after Cu-enriched livestock manure applications 总被引:4,自引:0,他引:4
Fertilization of crops with livestock manure (LM) is a common waste disposal option, but repeated application of LM containing high concentrations of heavy metals such as Cu could lead to crop toxicity and environmental risk. To examine the Cu availability and uptake by wheat in a Mollisol affected by Cu-enriched LM, pot experiments were conducted. LM (376 mg kg−1 Cu originally) was spiked with different concentrations of Cu (0, 100, 200, 400, 600 and 800 mg kg−1 soil, added as CuSO4) to simulate soil Cu contamination by LM application. The results indicated that Cu was predominately distributed in organic bound fraction, while the most drastic increase was found in reducible fraction. Acid-extractable fraction played a more important role than other fractions in controlling the mobility and bioavailability of Cu. DTPA-extractable Cu may overestimate the Cu bioavailability since DTPA solution could extract soluble and part of stable forms. The application of LM at 1% level significantly decline the Cu mobility, but that at 3% level exhibited the opposite effect.Although the quantities of Cu in wheat was very low compared with the accumulation in soil, Cu concentrations in roots increased evidently from 12 to 533 mg kg−1 and that in aerial parts were in a narrow range from 12.1 to 32.7 mg kg−1, indicating the more sensitivity of roots to the Cu toxicity. The Cu concentrations in grains after 3% manure application did not approach the threshold for Cu toxicity (<20 mg kg−1) even at higher Cu addition rates. 相似文献
985.
Köllo Z Palcsu L Major Z Papp L Molnár M Ranga T Dombóvári P Manga L 《Journal of environmental radioactivity》2011,102(1):53-59
Tritium occurs in nature in trace amounts, but its concentration is changing due to natural and artificial sources. Studies focusing on natural tritium have to take into account the effect of artificial sources. Also, the impact of tritium is an important issue in environmental protection, e.g. in connection with the emissions from nuclear power plants. The present work focuses on the rain washout of tritium emitted from the Paks nuclear power plant in Hungary. Rainwater collectors were placed around the plant and after a period of precipitation, rainwater was collected and analysed for tritium content. Samples were analysed using low-level liquid scintillation counting, with some also subject to the more accurate 3He ingrowth method. The results clearly show the trace of the tritium plume emitted from the plant; however, values are only about one order of magnitude higher than environmental background levels. A washout model was devised to estimate the distribution of tritium around the plant. The model gives slightly higher concentrations than those measured in the field, but in general the agreement is satisfactory. The modelled values demonstrate that the effect of the plant on rainwater tritium levels is negligible over a distance of some kilometres. 相似文献
986.
赣江流域淡水生态系统完整性与健康状态的鱼类F-IBI值评价 总被引:1,自引:0,他引:1
河流生态系统是地球上最为复杂的生态系统之一,它触及到自然环境所有部分,且几乎与各方面的人类活动均存在直接或间接的联系。河流生态学中最具活力的领域之一就是生态系统健康研究。鱼类是最早建立的生物完整性和健康评价的生物类群,一直以来被广为应用。在调查赣江流域17条一级支流和干流的不同江段的鱼类资源之后,首次通过鱼类完整性指数(F IBI)来评价赣江流域生态系统的健康状态。研究结果表明:赣江流域近70%调查样点鱼类群落完整性处于一般的状态,25%调查样点处于较好状态,5%调查样点则处于差的状态;赣江水系各河流的鱼类群落完整性均处于差-一般的水平。总之,流域支干流的水生态系统健康处于差-一般的状态。认为鱼类完整性受损与人工筑坝和蓄水等人类活动密不可分。建议开展系列补救措施,如增加鱼道或鱼梯等 相似文献
987.
This article examines the thermal decomposition of alpha-cypermethrin, one of the most common pyrethroid pesticides. The objective was to identify its decomposition pathways and to gain an understanding into the formation of toxic species in the environment, including those that may behave in combustion systems, especially in fires in the environment, as precursors for PCDD/F (polychlorinated dibenzo-p-dioxins and dibenzofurans). The experiments were conducted under non-oxidative conditions using a tubular reactor housed in a three-zone heating furnace and operated with a dilute stream of alpha-cypermethrin in 99.999% nitrogen. The condensable products were identified and quantitated, after being collected in a cold solvent trap and in an activated charcoal cartridge. The study revealed the formation of pollutants including precursors of toxic PCDD/F such as diphenyl ether and phenol. It was also found that the decomposition of alpha-cypermethrin involved parallel pathways of an unusual vinylcyclopropane rearrangement-cum-aromatisation reaction transforming alpha-cypermethrin and a rupture of the C(O)OC(CN) linkage. The former is similar to that occurring in the decomposition of permethrin pesticide, whereas the latter constitutes a newly discovered channel for the formation of pollutants. Density functional theory (DFT) calculations allowed us to attribute the occurrence of the second pathway to the effect of the cyanide group in significantly weakening the OC bond. 相似文献
988.
Jian-Guang Wu Xiang-Yu Meng Xiao-Meng Liu Xian-Wei Liu Zhi-Xia Zheng De-Qian Xu Guo-Ping Sheng Han-Qing Yu 《Environmental management》2010,46(4):610-617
Life cycle assessment (LCA) was applied to analyze a food-processing wastewater treatment plant and investigate the economic
and environmental effects of the plant. With the long-term operational data of this plant, an inventory of relative inputs,
e.g., flow rate, chemical oxygen demand (COD), and suspended solids, etc., and outputs of the plant, e.g., effluent COD and
suspended solids, methane production, etc., was compiled. The potential environmental effects associated with those inputs
and outputs were evaluated, and the results of the inventory analysis and impact assessment phases of the plant were interpreted.
One feature of this study was the assessment of the treatment plant based on both energy and material flows. Another feature
was the establishment of an assessment model with an integration of plant operating parameters, system recognition and grey
relation. The analytical results are helpful for the design and operation of wastewater treatment plants. 相似文献
989.
990.
C. R. Chen I. R. Phillips L. L. Wei Z. H. Xu 《Environmental science and pollution research international》2010,17(5):1110-1118