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31.
Vegetation stress detection through chlorophyll a + b estimation and fluorescence effects on hyperspectral imagery 总被引:2,自引:0,他引:2
Zarco-Tejada PJ Miller JR Mohammed GH Noland TL Sampson PH 《Journal of environmental quality》2002,31(5):1433-1441
Physical principles applied to remote sensing data are key to successfully quantifying vegetation physiological condition from the study of the light interaction with the canopy under observation. We used the fluorescence-reflectance-transmittance (FRT) and PROSPECT leaf models to simulate reflectance as a function of leaf biochemical and fluorescence variables. A series of laboratory measurements of spectral reflectance at leaf and canopy levels and a modeling study were conducted, demonstrating that effects of chlorophyll fluorescence (CF) can be detected by remote sensing. The coupled FRT and PROSPECT model enabled CF and chlorophyll a + b (Ca + b) content to be estimated by inversion. Laboratory measurements of leaf reflectance (r) and transmittance (t) from leaves with constant Ca + b allowed the study of CF effects on specific fluorescence-sensitive indices calculated in the Photosystem I (PS-I) and Photosystem II (PS-II) optical region, such as the curvature index [CUR; (R675.R690)/R2(683)]. Dark-adapted and steady-state fluorescence measurements, such as the ratio of variable to maximal fluorescence (Fv/Fm), steady state maximal fluorescence (F'm), steady state fluorescence (Ft), and the effective quantum yield (delta F/F'm) are accurately estimated by inverting the FRT-PROSPECT model. A double peak in the derivative reflectance (DR) was related to increased CF and Ca + b concentration. These results were consistent with imagery collected with a compact airborne spectrographic imager (CASI) sensor from sites of sugar maple (Acer saccharum Marshall) of high and low stress conditions, showing a double peak on canopy derivative reflectance in the red-edge spectral region. We developed a derivative chlorophyll index (DCI; calculated as D705/D722), a function of the combined effects of CF and Ca + b content, and used it to detect vegetation stress. 相似文献
32.
The potential of concentrating solar power plant (CSPP) technology in Jordan is assessed and the next steps for development of the first CSPP in the country are presented. For this purpose, a prototype of a 50 MW CSPP for electricity generation in Jordan is proposed and analysis of its economic feasibility has been performed. Moreover, a calculation model – using the concept design of the proposed CSPP, and the solar irradiation data – was developed to estimate the energy yield of the plant. Based on the analyzed solar irradiation data, it was found that Jordan has an outstanding potential for CSPP, especially in the southern locations of the country such as Quweira. At the same time Jordan's energy master plan is seeking for independent energy supply and for an increasing share of renewable energies. Furthermore, Jordan's demand curve over a day closely matches the electricity production of the proposed plant. Combination of these factors creates a very favorable situation. Therefore, establishment of the proposed 50 MW CSPP is highly recommended not only in Jordan, but also in many other countries, which have similar political and economical conditions such as those countries located in the Middle East and North Africa (MENA) region. 相似文献
33.
Kyrre Sundseth Jozef M. Pacyna Elisabeth G. Pacyna John Munthe Mohammed Belhaj Stefan Astrom 《Journal of Cleaner Production》2010,18(4):386-394
Anthropogenic processes have increased the exposure of humans and wildlife to toxic methyl mercury (MeHg). Mercury emissions will increase by about 25% between 2005 and 2020, if the present trajectory is maintained. A global assessment of societal damages caused by the ingestion of methyl mercury, based merely on loss of IQ (Intelligence Quotient), suggests that the annual cost will be approximately US$3.7 billion (2005 dollars) in 2020. The corresponding cost of damages resulting from the inhalation of methyl mercury is estimated at US$2.9 million (2005 dollars). Under a higher degree of emission control such as in the case of the Extended Emission Control (EXEC) and the Maximum Feasible Technological Reduction (MFTR) scenarios, total emissions could decrease in the period 2005–2020 by about 50–60%. The corresponding annual benefits in 2020 are estimated to be about US$1.8–2.2 billion (2005 dollars). Large economic benefits can be achieved by reducing global mercury emissions. 相似文献
34.
Dissolution of raw phosphate (apatite) in sea water of the Gulf of Aqaba was investigated through lab incubation experiments. Three types from three different sources (Al-Hasa, Al-Abyad and Esh-Shydiya) have been used for these experiments. Impact of quantity, grain size, and source (type) of raw phosphate on dissolution rate were studied. Statistical analysis shows significant differences between the results obtained from comparing each two weights; as weight of apatite increased, dissolved inorganic phosphate-phosphorus (DIP) and fluoride in sea water solution increased. The differences between the dissolution rates of raw phosphate from the three sites were not significant while the differences between the different grain size fractions were significant. Dissolution rates were inversely related to particle size. Using a worst-case scenario, a conservative estimate of the maximum increase in DIP in seawater of the Gulf of Aqaba due to the apatite particles lost to the sea during ship loading resulted in DIP concentrations of 0.03 μM per year. As the residence time of the water in the Gulf of Aqaba is about one year, the DIP concentration will not increase by more than 0.03 μM under the estimated annual quantity of exported phosphate. Fluoride will not increase by more than 0.03 mg/l under the same conditions. 相似文献
35.
Waled Morsy El-Senousy Ahmed Mohammed El-Sayed Ragab Eman Mohammed Abd El Hamed Handak 《Food and environmental virology》2015,7(2):132-141
The objective of this study is to compare the prevalence of rotaviruses groups A and C in Egyptian children and aquatic environment. From 110 stool specimens of children with acute diarrhea and using RT-PCR, 35 samples (31.8 %) were positive for human rotavirus group A and 15 samples (13.6 %) were positive for human rotavirus group C. From 96 samples collected from Zenin wastewater treatment plant over a 2-year period (November 2009–October 2011) and using RT-PCR, rotavirus group A was detected in (4/24) 16.7 %, (5/24) 20.8 %, (4/24) 16.7 %, and (4/24) 16.7 %, while rotavirus group C was detected in (2/24) 8.3 %, (3/24) 12.5 %, (3/24) 12.5 %, and (0/24) 0 % in raw sewage, after primary sedimentation, after secondary sedimentation, and after final chlorination, respectively. Moreover, from 96 samples collected from El-Giza water treatment plant over a 2-year period (November 2009–October 2011), rotavirus group A was detected in (7/24) 29.2 %, (6/24) 25 %, (5/24) 20.8 %, and (3/24) 12.5 %, while rotavirus group C was detected in (3/24) 12.5 %, (1/24) 4.2 %, (1/24) 4.2 %, and (0/24) 0 % in raw Nile water, after sedimentation, after sand filtration, and after final chlorination, respectively. Using SYBR Green real-time RT-PCR, the number of human rotavirus group A genome or infectious units was higher than rotavirus group C. VP6 sequence analysis of the RT-PCR positive rotavirus group C samples revealed that four clinical specimens and three environmental samples showed similar sequences clustered with Moduganari/Human Nigerian strain AF 325806 with 98 % homology, and two clinical specimens and one environmental sample showed similar sequences clustered with Dhaka CB/Human Bangladesh strain AY 754826 with 97 % homology. 相似文献
36.
Omar Farah Nadia Loo Yu Xiang Lee Yei Lie Dzulkornain Chairil Anuar Mohammed P.Mohd Afandi Samsu Azhari Baharuddin 《环境科学学报(英文版)》2015,28(2):81-94
Co-composting of poultry manure and rubber wood sawdust was performed with the ratio of 2:1(V/V) for a period of 60 days. An investigation was carried out to study the extracellular enzymatic activities and structural degradation utilizing Fourier transform infrared spectroscopy(FT-IR), thermogravimetry and differential thermal analysis(TG/DTA)and scanning electron microscopy(SEM). The microbial succession was also determined by using denaturing gel gradient electrophoresis(DGGE). The compost was able to reach its highest temperature of 71°C at day 3 and stabilized between 30 and 40°C for 8 weeks.CMCase, FPase and β-glucosidase acted synergistically in order to degrade the cellulosic substrate. The xylanase activities increased gradually during the composting and reached the peak value of 11.637 U/g on day 35, followed by a sharp decline. Both Li P and Mn P activities reached their peak values on day 35 with 0.431 and 0.132 U/g respectively. The FT-IR spectra revealed an increase in aromaticity and a decrease in aliphatic compounds such as carbohydrates as decomposition proceeded. TGA/DTG data exhibited significant changes in weight loss in compost samples, indicating degradation of organic matter. SEM micrographs showed higher amounts of parenchyma exposed on the surface of rubber wood sawdust at day 60, showing significant degradation. DGGE and 16 S r DNA analyses showed that Burkholderia sp., Pandoraea sp., and Pseudomonas sp. were present throughout the composting process. Ornithinibacillus sp. and Castellaniella ginsengisoli were only found in the initial stage of the composting, while different strains of Burkholderia sp. also occurred in the later stage of composting. 相似文献
37.
Decentralized forest management is a pivotal approach in Ethiopia for balancing biodiversity conservation with demand for economic development, and for improving forest-dependent local peoples’ livelihoods. With the aim of filling the literature gap on Ethiopia, this paper explores the dynamics of decentralization in the forestry sector using the actor-power-accountability framework. Generally, three forms of decentralization are practiced: deconcentration to government administrative branches, devolution of selected decision-making power to local people, and delegation to enterprises. Although transfer of meaningful discretionary power to local people or to downwardly accountable lower-tier governments is a precondition for achieving positive outcomes from decentralization, this prerequisite has been realized in none of the three forms decentralization. Overall, three important trends emerged from the latest decentralization reform, which was a switch from the conservation-oriented deconcentration form of decentralization to the income generation-oriented delegation form of decentralization. Those trends are as follows: monetary income generation for local people through enterprise, albeit with possible risk of being deprived of income and subsistence opportunities on which local people depend for their livelihoods; moving decision-making power away from the grassroots; and lack of incentive to manage natural forests, a major source of biodiversity. 相似文献
38.
Salim M.Mohammed 《Ambio-人类环境杂志》2002,31(8)
坦桑尼亚的海岸带(图1)有多种生物栖息地,其中包括珊瑚礁、红树林、海草床、沙坝、湿地和沙滩.除了承担海岸带所有功能中的基本连接作用外,这些海岸带栖息地还提供了生物和非生物资源. 相似文献
39.
Amina Chnirhe Mourad Harir Basem Kanawati Mohammed El Azzouzi Istvan Gebefgi Philippe Schmitt-Kopplin 《环境科学学报(英文版)》2012,24(9):1686-1693
The photodegradation of mefenpyrdiethyl (MFD), an herbicide safener, was investigated in aqueous suspensions by using Degussa P-25 and Hombikat UV100 titanium oxide under simulated sunlight irradiation. The effects of initial concentration of the herbicide, pH, catalysts and hydrogen peroxide doses as well as their combinations were studied and optimized. Accordingly, the kinetic parameters were determined and the effectiveness of the processes was assessed by calculating the rate constants. A pseudo first-order kinetics was observed. Under experimental conditions, the degradation rate constants were strongly influenced using P-25 and no noticeable effect was observed for Hombikat UV100. DFT calculations with B3LYP/6-311+G(2d,p)//B3LYP/6-31+G(d,p) level of theory were performed to check whether significant conformational changes occur when the charge state of the MFD substrate changes and whether these changes could play a role in the dependency of photodegradation rate constant on the studied pH. High resolution mass spectrometry (FT-ICR/MS) was implemented to identify the main degradation products. 相似文献
40.
Mohammed Moussavian Larry Samuelson 《Journal of Environmental Economics and Management》1984,11(2):139-146
Hotelling's r-percent rule does not hold for monopoly extractors of durable exhaustible resources. An example with a nondurable resource in which the rule also fails to hold is presented. An economy with a fixed average propensity to save is modelled. The monopoly extractor recognizes that resource extraction, by affecting output and hence capital accumulation, affects future demand. The firm exploits this effect by causing the marginal profitability of extraction to grow faster or slower than the rate of interest, depending upon initial conditions. Conditions are developed under which the growth rate will be less than the interest rate. 相似文献