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排序方式: 共有10000条查询结果,搜索用时 13 毫秒
941.
Wan Azlina Wan Ab. Karim Ghani Iffah Farizan Rusli Dayang Radiah Awang Biak Azni Idris 《Waste management (New York, N.Y.)》2013,33(5):1276-1281
Tremendous increases in biodegradable (food waste) generation significantly impact the local authorities, who are responsible to manage, treat and dispose of this waste. The process of separation of food waste at its generation source is identified as effective means in reducing the amount food waste sent to landfill and can be reused as feedstock to downstream treatment processes namely composting or anaerobic digestion. However, these efforts will only succeed with positive attitudes and highly participations rate by the public towards the scheme. Thus, the social survey (using questionnaires) to analyse public’s view and influencing factors towards participation in source separation of food waste in households based on the theory of planned behaviour technique (TPB) was performed in June and July 2011 among selected staff in Universiti Putra Malaysia, Serdang, Selangor. The survey demonstrates that the public has positive intention in participating provided the opportunities, facilities and knowledge on waste separation at source are adequately prepared by the respective local authorities. Furthermore, good moral values and situational factors such as storage convenience and collection times are also encouraged public’s involvement and consequently, the participations rate. The findings from this study may provide useful indicator to the waste management authorities in Malaysia in identifying mechanisms for future development and implementation of food waste source separation activities in household programmes and communication campaign which advocate the use of these programmes. 相似文献
942.
James E. Bonany Paul J. Van Geel H. Burak Gunay O. Burkan Isgor 《Waste management (New York, N.Y.)》2013,33(5):1215-1228
A landfill operated in Ste. Sophie, Québec, Canada was instrumented to better understand the waste stabilization process in northern climates. Instrument bundles were placed within the waste to monitor temperature, settlement, oxygen, moisture content, total load, mounding of leachate and electrical conductivity. A finite element model was developed to simulate the heat budget for the first waste lift placed in the winter months and was calibrated using the first 10.5 months of collected temperature data. The calibrated model was then used to complete a sensitivity analysis for the various parameters that impact the heat budget. The results of the analysis indicated that the heat required for phase change to thaw the liquid fraction within frozen waste had a significant impact on the heat budget causing sections of waste to remain frozen throughout the simulation period. This was supported by the data collected to date at Ste. Sophie and by other researchers indicating that frozen waste placed during the winter months can remain frozen for periods in access of 1.5 years. 相似文献
943.
A. Cammarota R. Chirone P. Salatino R. Solimene M. Urciuolo 《Waste management (New York, N.Y.)》2013,33(6):1397-1402
Combustion of two semi-dried sewage sludges in a 110 mm has been characterized in terms of particulate and gaseous emissions. Sludges differed in that they had been conditioned – at the flocculation stage of wastewater treatment – either with Ca-based inorganics or with polyelectrolytes. Combustion was efficient for both sewage sludges under all the operating conditions tested. Significant differences have instead been observed between the two types of sewage sludges as regards particulate and macro-pollutant gaseous emissions (SO2, NOx). NOx formation is significantly influenced by ash accumulation inside the bed only when sewage sludge conditioned with Ca-based inorganics is fired. The time-resolved profiles of NOx concentration and the mass flow rate of the elutriated fines have been worked out to evaluate the fuel nitrogen yield to NOx as a function of ash accumulated inside the bed divided by the air mass feed rate. Experimental results have been compared with data present in literature. 相似文献
944.
Reliable estimates of animal density are fundamental to understanding ecological processes and population dynamics. Furthermore, their accuracy is vital to conservation because wildlife authorities rely on estimates to make decisions. However, it is notoriously difficult to accurately estimate density for wide‐ranging carnivores that occur at low densities. In recent years, significant progress has been made in density estimation of Asian carnivores, but the methods have not been widely adapted to African carnivores, such as lions (Panthera leo). Although abundance indices for lions may produce poor inferences, they continue to be used to estimate density and inform management and policy. We used sighting data from a 3‐month survey and adapted a Bayesian spatially explicit capture‐recapture (SECR) model to estimate spatial lion density in the Maasai Mara National Reserve and surrounding conservancies in Kenya. Our unstructured spatial capture‐recapture sampling design incorporated search effort to explicitly estimate detection probability and density on a fine spatial scale, making our approach robust in the context of varying detection probabilities. Overall posterior mean lion density was estimated to be 17.08 (posterior SD 1.310) lions >1 year old/100 km2, and the sex ratio was estimated at 2.2 females to 1 male. Our modeling framework and narrow posterior SD demonstrate that SECR methods can produce statistically rigorous and precise estimates of population parameters, and we argue that they should be favored over less reliable abundance indices. Furthermore, our approach is flexible enough to incorporate different data types, which enables robust population estimates over relatively short survey periods in a variety of systems. Trend analyses are essential to guide conservation decisions but are frequently based on surveys of differing reliability. We therefore call for a unified framework to assess lion numbers in key populations to improve management and policy decisions. 相似文献
945.
946.
María Pía Areal M. Lorena Arciniegas Fernanda Horst Verónica Lassalle Francisco H. Sánchez Vera A. Alvarez Jimena S. Gonzalez 《Journal of Polymers and the Environment》2018,26(8):3129-3138
Scientific and technological researches are devoted to obtain materials capable of retaining different kinds of pollutants, contributing to contamination solutions. In this context, hydrogels have emerged as great candidates because of their excellent absorption properties as well as good mechanical, thermal and chemical properties. More specifically, ferrogels (magnetic gels) present the extra advantage of being easily manipulated by a permanent magnet. Here, we present the results derived from the application of ferrogels as efficient tools to extract heavy metal pollutants from wastewater samples. The gels were prepared following the method of freezing and thawing of a polyvinyl alcohol aqueous solution with magnetic nanoparticles coated with polyacrylic acid. Ferrogels were fully characterized and their ability to retain Cu2+ and Cd2+, as model heavy metals, was studied. Thus kinetics and mechanisms of adsorption were evaluated and modeled. The concentration of MNPs on the PVA matrix was key to improve the adsorption capability (approximately the double of retention is improved by the MNPs addition). The adsorption kinetics was determined as pseudo-second order model, whereas the Langmuir model was the most appropriate to explain the behavior of the gels. Finally reuse ability was evaluated to determine the real potential of these materials, the ferrogels demonstrated high efficiency up to about five cycles, retaining about 80–90% of their initial adsorption capability. All the results indicated that the materials are promising candidates able to compete with the commercial technology regarding to water remediation. 相似文献
947.
948.
A method was developed for measurement of active oxygen production in embryonic stages of the brown seaweed Fucus spiralis, using the label CM-DCFH-DA. Active oxygen species convert the label into the green fluorescent CM-DCF (exc/em 488/530 nm)
that is detected via confocal laserscan microscopy and quantitative image analysis. Loading of the label did not harm the
embryos; loading efficiency was age-independent, and the esterases needed for conversion to CM-DCFH were not inhibited by
the effective UV dose (2 W m−2) applied in the experiments. After correction for daily variation of the laser power, and calibration with DCF standard solutions,
this automated analysis of confocal images rendered active oxygen concentrations in fucoid embryos (μM DCF). An experiment
was designed for the assessment of active oxygen production following irradiance stress in the light-sensitive embryos. Dim-light-acclimated,
1-, 2- and 4-day-old embryos were transferred for 60 min to defined high-light conditions (4π-irradiance 300 μmol photons
m−2 s−1), optionally without UV radiation, including UVA, or including UVA plus UVB. PSII yield measurements (PAM fluorometer) were
carried out in order to assess the degree of photoinhibition under these light conditions. The imposed light stress initially
caused a rapid decrease of the PSII yields (ΦP). With increasing embryo age, minimum ΦP values attained under light stress remained higher. Consequently, electron transport rates (ETR) would increase with embryo
age, i.e., with the development of their photosynthetic apparatus. Active oxygen production increased with ETR, and when UVB
was included, relatively greater amounts of active oxygen were produced. A slow, second-phase decrease of ΦP under light stress that was proportional to active oxygen production indicated that some photooxidative damage was caused,
in particular during UVB exposure. Recovery from light stress was a rapid process in the absence of UVB; in such cases ΦP was almost restored to the initial values within 60 min. The relative state of recovery of ΦP was correlated with both the effective UV dose and active oxygen production rate (DCF). Recovery was slowest in embryos exposed
for 60 min to an experimental UVB dose, which was representative of a situation at low tide, on a sunny day. The results suggest
that active oxygen may cause an in situ inhibition of growth of the earliest life stages of F. spiralis.
Received: 26 January 2000 / Accepted: 4 September 2000 相似文献
949.
We examined the vertical distributions of scallop (Placopecten magellanicus) veligers in deep (0.6 m diameter, 9.5 m deep) polyethylene mesocosms from December 1991 to January 1992. In the mesocosms
temperature stratification varied from 0 to 1.5 °C. Profiles of vertical distribution revealed several repeated patterns.
Peaks in veliger numbers often appeared at the water surface and just above the thermocline. Higher density patches were seen
below the surface peaks, and revealed the presence of bio-convective cells. Distribution away from these discontinuities was
usually even. Distribution of veligers was affected by thermoclines above 1.0 °C. Responses to thermoclines varied with larval
age and time of day, and 28 to 30 d veligers passed in both directions through a 1.5 °C thermocline. We conclude that larval
behaviour is a major determinant of whether veligers pass through a thermocline. Kinematic viscosity may play a role in perception
of temperature changes. Two potential consequences of such behaviour are (1) remaining in more productive upper water layers,
where feeding opportunities are enhanced, and (2) increased horizontal transport in the region of the thermocline, which may
enhance recruitment.
Received: 15 May 1996 / Accepted: 11 May 2000 相似文献
950.
Y. Nassiri P. S. Rainbow C. Amiard-Triquet F. Rainglet B. D. Smith 《Marine Biology》2000,136(3):477-484
The talitrid amphipod crustacean Orchestia gammarellus (Pallas) was collected from metal-contaminated (Dulas Bay, Gironde) and control (Millport) sites in the UK and France. Irrespective
of site of origin, the amphipods showed the same physiological mechanism of trace-metal detoxification, involving the ventral
caeca. Copper was always present in lysosomal residual bodies in the ventral caeca. Following laboratory exposure to zinc
and cadmium, the lysosomes usually contained both copper and zinc but cadmium was not detectable. The lysosomal copper concentration
is positively correlated to that of sulphur, while the concentration of lysosomal zinc is related to that of phosphorus. Results
are interpreted in terms of the differential rates of turnover of metallothioneins chelating copper, zinc or cadmium.
Received: 9 February 1999 / Accepted: 2 December 1999 相似文献