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651.
The continuous extraction of wood and the conversion of forest to small- and large-scale agricultural parcels is rapidly changing the land cover of the mount Cameroon region. The changes occur at varying spatial scales most often not more than 2ha for the small-scale subsistence farms and above 10ha for the extensive agricultural plantations of cocoa and palm. Given the importance of land use and land cover data in conservation planning, accurate and efficient techniques to provide up-to-date change information are required. A number of techniques for realising the detection of land cover dynamics using remotely sensed imagery have been formulated, tested and assessed with the results varying with respect to the change scenario under investigation, the information required and the imagery applied. In this study the Change Vector Analysis (CVA) technique was implemented on multitemporal multispectral Landsat data from the Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM) sensors to monitor the dynamics of forest change in the mount Cameroon region. CVA was applied to multi-temporal data to compare the differences in the time-trajectory of the tasseled cap greenness and brightness for two successive time periods - 1987 and 2002. The tasseled cap was selected as biophysical indicator because it optimises the data viewing capabilities of vegetation, representing the basic types of land cover - vegetation, soil and water. Classes were created arbitrarily to predict the technique's potential in monitoring forest cover changes in the mount Cameroon region. The efficiency of the technique could not be fully assessed due to the inavailability of sufficient ground truth data. Assessment was based on the establishment of an error matrix of change versus no-change. The overall accuracy was 70%. The technique nevertheless demonstrated immense potentials in monitoring forest cover change dynamics especially when complemented with field studies. 相似文献
652.
Van Lancker F Adams A Delmulle B De Saeger S Moretti A Van Peteghem C De Kimpe N 《Journal of environmental monitoring : JEM》2008,10(10):1127-1133
An automated headspace solid phase microextraction method followed by GC-MS analysis was used to evaluate and compare the in vitro production of microbial volatile organic compounds (MVOCs) on malt extract agar, plasterboard and wallpaper. Five fungal strains were isolated from the walls of water-damaged houses and identified. In addition, four other common molds were studied. In general, MVOC production was the highest on malt extract agar. On this synthetic medium, molds typically produced 2-methylpropanol, 2-methylbutanol and 3-methylbutanol. On wallpaper, mainly 2-ethylhexanol, methyl 2-ethylhexanoate and compounds of the C8-complex such as 1-octene-3-ol, 3-octanone, 3-octanol and 1,3-octadiene were detected. The detection of 2-ethylhexanol and methyl 2-ethylhexanoate indicates an enhanced degradation of the substrate by most fungi. For growth on plasterboard, no typical metabolites were detected. Despite these metabolite differences on malt extract agar, wallpaper and plasterboard, some molds also produced specific compounds independently of the used substrate, such as trichodiene from Fusarium sporotrichioides and aristolochene from Penicillium roqueforti. Therefore, these metabolites can be used as markers for the identification and maybe also mycotoxin production of these molds. All five investigated Penicillium spp. in this study were able to produce two specific diterpenes, which were not produced by the other species studied. These two compounds, which remain unidentified until now, therefore seem specific for Penicillium spp. and are potentially interesting for the monitoring of this fungal genus. Further experiments will be performed with other Penicillium spp. to study the possibility that these two compounds are specific for this group of molds. 相似文献
653.
Kurt Lewin and others have showed that group discussion effectively changed attitudes and behaviors compared to individually targeted messages. This study examines the roles of normative and informational social influence in this effect. High school students heard a message about replacing toxic products with nontoxic alternatives; classes were randomly assigned to hear the message delivered as a lecture or via guided group discussion. For female students (N=250 in 26 classes), HLM mediation analyses suggested normative influence predominated: Discussion was more effective than lecture and this effect was fully mediated by students’ perceptions that other students endorsed nontoxics. Content analyses of students’ comments indicated that three kinds of remarks led female students to this perception: (1) sharing knowledge about nontoxics; (2) asking questions about nontoxics; and (3) little praise for toxic products. For male students in separate HLM analyses (N=107 in 19 of the same classes), informational influence was most apparent: Postmeeting attitudes were higher after discussion than lecture, and this effect was partially mediated by cognitive elaboration about the message (but not perceptions others endorsed the message). In addition, males’ quiz grades were higher after discussion, and students’ comments fully mediated the discussion to quiz grades relationship. Results support the importance of hearing others’ promessage comments for changing socially motivated behaviors, although the routes of influence appear to differ for these samples of male and female students. 相似文献
654.
Manju R. Agrawal John Boland Barbara Ridley 《Environmental Modeling and Assessment》2013,18(4):481-492
In the financial year 2011–2012, wind farms supplied 26 % of South Australia’s electricity demand according to the Australian Energy Market Operator’s report. This contribution has risen from zero in 2003. The operation of the electricity grid depends heavily on knowledge of the variability of supply. Wind farm output displays similar conditional volatility as financial market variables. In this paper, a new method of estimating wind farm output volatility on a 5-min time scale is developed through the use of higher-frequency wind farm output data. First, an autoregressive model for the high-frequency data is developed, and it is used to derive a volatility measure for 5-min data. The results are also true in certain general situations when the high-frequency data follow an autoregressive moving average process or exhibits long memory features. The methods described here are analogous to realised volatility measures used in financial series, except that wind farm output data are measured at uniform intervals, unlike random trading times for financial transactions. 相似文献
655.
Shippi Dewangan Rajan Chakrabarty Barbara Zielinska Shamsh Pervez 《Environmental monitoring and assessment》2013,185(11):9279-9286
Worshipping activity is a customary practice related with many religions and cultures in various Asian countries, including India. Smoke from incense burning in religious and ritual places produces a large number of health-damaging and carcinogenic air pollutants include volatile organic compounds (VOCs) such as formaldehyde, benzene, 1,3 butadiene, styrene, etc. This study evaluates real-world VOCs emission conditions in contrast to other studies that examined emissions from specific types of incense or biomass material. Sampling was conducted at four different religious places in Raipur City, District Raipur, Chhattisgarh, India: (1) Hindu temples, (2) Muslim graveyards (holy shrines), (3) Buddhist temples, and (4) marriage ceremony. Concentrations of selected VOCs, respirable particulate matter (aerodynamic diameter, <5 μm), carbon dioxide, and carbon monoxide were sampled from the smoke plumes. Benzene has shown highest emission factor (EF) among selected volatile organic compounds in all places. All the selected religious and ritual venues have shown different pattern of VOC EFs compared to laboratory-based controlled chamber studies. 相似文献
656.
The migration pathways of heavy metals derived from an area previously in agricultural use was investigated in the Wielkopolski
National Park (mid-western Poland). The heavy metals involved (Cd, Cu, Cr, Pb, Ni and Zn) were determined in groundwater,
the springs that feed Lake Góreckie and the lake itself. In order to show how the heavy metals may be set free and what is
their biological availability, soil and sediment samples were subjected to single-stage extraction, using 0.01 M CaCl2, 0.02 M EDTA, 0.005 M DTPA, 0.1 M HCl, 1 M HCl and de-ionised water. Varying metal concentrations were recorded in the water
samples during the study period (from November 2009 to July 2010), usually with higher values in winter and lower ones in
summer. The seasonal changes may be ascribed to natural processes taking place in the ground- and surface waters of Lake Góreckie.
On the other hand, the concentration levels (mostly of Cd, Pb and Cr) are indicative of anthropogenic activity. It should
be mentioned in this context that the highest metal concentrations were found in the soil layer. The concentrations were also
found to exceed both the Polish and the World Health Organization water-quality standards. It appears that the soils are highly
contaminated, mostly with cadmium. The long-lasting effect of acid precipitation in the area makes it possible for immobile
forms to become mobile, thus facilitating further migration into the environment. 相似文献
657.
Isabelle M. Cozzarelli Barbara A. Bekins Robert P. Eganhouse Ean Warren Hedeff I. Essaid 《Journal of contaminant hydrology》2010,111(1-4):48-64
Benzene and alkylbenzene biodegradation rates and patterns were measured using an in situ microcosm in a crude-oil contaminated aquifer near Bemidji, Minnesota. Benzene-D6, toluene, ethylbenzene, o-, m- and p-xylenes and four pairs of C3- and C4-benzenes were added to an in situ microcosm and studied over a 3-year period. The microcosm allowed for a mass-balance approach and quantification of hydrocarbon biodegradation rates within a well-defined iron-reducing zone of the anoxic plume. Among the BTEX compounds, the apparent order of persistence is ethylbenzene > benzene > m,p-xylenes > o-xylene ≥ toluene. Threshold concentrations were observed for several compounds in the in situ microcosm, below which degradation was not observed, even after hundreds of days. In addition, long lag times were observed before the onset of degradation of benzene or ethylbenzene. The isomer-specific degradation patterns were compared to observations from a multi-year study conducted using data collected from monitoring wells along a flowpath in the contaminant plume. The data were fit with both first-order and Michaelis-Menten models. First-order kinetics provided a good fit for hydrocarbons with starting concentrations below 1 mg/L and Michaelis-Menten kinetics were a better fit when starting concentrations were above 1 mg/L, as was the case for benzene. The biodegradation rate data from this study were also compared to rates from other investigations reported in the literature. 相似文献
658.
L.-J. Sally Liu Harish C. Phuleria Whitney Webber Mark Davey Douglas R. Lawson Robert G. Ireson Barbara Zielinska John M. Ondov Christopher S. Weaver Charles A. Lapin Michael Easter Thomas W. Hesterberg Timothy Larson 《Atmospheric environment (Oxford, England : 1994)》2010,44(28):3422-3431
We monitored two Seattle school buses to quantify the buses’ self pollution using the dual tracers (DT), lead vehicle (LV), and chemical mass balance (CMB) methods. Each bus drove along a residential route simulating stops, with windows closed or open. Particulate matter (PM) and its constituents were monitored in the bus and from a LV. We collected source samples from the tailpipe and crankcase emissions using an on-board dilution tunnel. Concentrations of PM1, ultrafine particle counts, elemental and organic carbon (EC/OC) were higher on the bus than the LV. The DT method estimated that the tailpipe and the crankcase emissions contributed 1.1 and 6.8 μg m?3 of PM2.5 inside the bus, respectively, with significantly higher crankcase self pollution (SP) when windows were closed. Approximately two-thirds of in-cabin PM2.5 originated from background sources. Using the LV approach, SP estimates from the EC and the active personal DataRAM (pDR) measurements correlated well with the DT estimates for tailpipe and crankcase emissions, respectively, although both measurements need further calibration for accurate quantification. CMB results overestimated SP from the DT method but confirmed crankcase emissions as the major SP source. We confirmed buses’ SP using three independent methods and quantified crankcase emissions as the dominant contributor. 相似文献
659.
Barbara Gabriella Renzi Matthew Cotton Ralf Barkemeyer 《Environmental Communication: A Journal of Nature and Culture》2017,11(5):624-640
Nuclear power plays an important but controversial role in policies to ensure domestic energy security, fuel poverty reduction and the mitigation of climate change. Our article construes the problem of nuclear power in terms of social discourse, language and public choice; specifically examining the role that metaphors play in the policy domain. We empirically analyze metaphors as framing devices in nuclear energy policy debates in the UK between April 2009 and March 2013, thereby capturing the impact of the Fukushima nuclear disaster in 2011. We employ documentary analysis of major UK national broadsheet and tabloid newspapers, using electronic bibliographic tools to extract the metaphors. We then map these metaphors using a Type Hierarchy Analysis, which examines how elements of the target domain (energy technologies and policies) originate from a different source domain. Type hierarchies identify and categorize metaphors, defining the affectual and emotional responses associated with them, providing us with grounded insight into their role in shaping discourse and as a consequence influence public engagement with energy policy. Our analysis highlights three emergent domains of discourse metaphors and discusses the implications of their deployment. Metaphors were found to be classified into three different categories: Rebirth (Renaissance), Devastation (Apocalypse, Inferno, Genie and Bomb) and Sickness (Addiction and Smoking). 相似文献
660.
The Use of Zero‐Valent Iron (ZVI) Technology to Promote DDT and Dieldrin Degradation at Point Pelee National Park 下载免费PDF全文
Point Pelee National Park (PPNP) is highly contaminated with dichlorodiphenyltrichloroethane (DDT) and dieldrin due to the historical use of these two persistent organochlorine pesticides. Zero‐valent iron (ZVI) technology with and without amendments has been successfully used in the past to promote organochlorine pesticides degradation in several locations in North America and Europe. In this study, the use of two commercially available ZVI products, DARAMEND® and EHC®, to promote DDT and dieldrin degradation in PPNP's soil and groundwater were investigated. DARAMEND® was applied to PPNP's soil in a laboratory experiment and in an in situ pilot‐scale plot. In both cases, DARAMEND® did not significantly increase DDT or dieldrin degradation in treated soils. The effectiveness of EHC® was tested in a laboratory experiment that simulated the park's groundwater environment using PPNP's pesticide contaminated soil. The result was consistent with the one reported for DARAMEND®, in that there was no significant increase in DDT or dieldrin degradation in any of the samples treated with EHC®. These results demonstrate that both of these ZVI commercially available products are not suitable for in situ remediation at PPNP. ©2017 Wiley Periodicals, Inc. 相似文献