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91.
Four colonies of Acropora formosa were incubate with Na2
14CO3 for separate 2 h periods within a 24 h period, and then returned to the reef from which they were collected. Terminal branches were collected at intervals over the following 5 d and analysed for radioactivity associated with the skeleton and certain organic pools. Colonies incubated at night showed little or no loss of fixed radioactivity during the 5 d on the reef. However, 50–60% of photosynthetically-fixed 14C was lost from the terminal branches during the first 40 h on the reef. This loss of radioactivity probably resulted from release of mucus and dissolved organic carbon from the coral tissues. Most of the loss of photosynthetically-fixed 14C was due to decrease in the radioactivity of lipids (80% of the total 14C loss) and methanol-water soluble compounds. Determination of any sequencing in metabolic compartments was made difficult by the rapidity with which 14C dissappeared from most of the metabolic pools measured. 14C was incorporated into the skeleton throughout the 5 d on the reef, although the rate of incorporation was very low in colonies which had been incubated with Na2
14CO3 at night. 相似文献
92.
Cox SS Little JC Hodgson AT 《Journal of the Air & Waste Management Association (1995)》2001,51(8):1195-1201
The initial solid-phase concentration of volatile organic compounds (VOCs) is a key parameter influencing the emission characteristics of many indoor materials. Solid-phase measurements are typically made using solvent extraction or thermal headspace analysis. The high temperatures and chemical solvents associated with these methods can modify the physical structure of polymeric materials and, consequently, affect mass transfer characteristics. To measure solid-phase concentrations under conditions resembling those in which the material would be installed in an indoor environment, a new technique was developed for measuring VOC concentrations in vinyl flooring (VF) and similar materials. A 0.09-m2 section of new VF was punched randomly to produce -200 0.78-cm2 disks. The disks were milled to a powder at -140 degrees C to simultaneously homogenize the material and reduce the diffusion path length without loss of VOCs. VOCs were extracted from the VF particles at room temperature by fluidized-bed desorption (FBD) and by direct thermal desorption (DTD) at elevated temperatures. The VOCs in the extraction gas from FBD and DTD were collected on sorbent tubes and analyzed by gas chromatography/mass spectrometry (GC/MS). Seven VOCs emitted by VF were quantified. Concentration measurements by FBD ranged from 5.1 microg/g VF for n-hexadecane to 130 microg/g VF for phenol. Concentrations measured by DTD were higher than concentrations measured by FBD. Differences between FBD and DTD results may be explained using free-volume and dual-mobility sorption theory, but further research is necessary to more completely characterize the complex nature of a diffusant in a polymer matrix. 相似文献
93.
Preference rankings for 13 macrophytes were established for the subtidal herbivorous snail Lithopoma undosum using two-choice laboratory experiments and consumption rates. L. undosum did not discriminate among three kelp foods (Egregia menziesii, Eisenia arborea and Macrocystis pyrifera) but ate kelp preferentially and more rapidly over all but Ulva spp. among tested macrophytes. Secondary preferences were established for the red alga Pterocladiella capillacea, followed by the coralline Lithothrix aspergillum, whereas the brown seaweeds Zonaria farlowii and Halidrys dioica and the seagrass Phyllospadix
torreyi were the least preferred macrophytes. Fastest consumption rates (1.91 g day−1) were measured in trials consisting only of kelp foods. These results indicate that L. undosum exhibits clear feeding preferences even when given less-preferred, non-kelp macrophytes. Using an ash-marker technique, we
determined total organic, carbon, and nitrogen assimilation efficiencies (AE%) for six macroalgae used in preference trials.
Tested macrophytes were assimilated at different efficiencies but a pattern was not detected between AE (%) and a macrophyte’s
position in L. undosum’s preference hierarchy. Highest total organic AEs were found for P. capillacea (61.2%) and H. dioica (59.4%); lowest AEs were detected for E. menziesii (34.9%), a preferred dietary item. Nitrogen was assimilated from red algae with higher efficiencies (74.9–84.3%) than from
brown or green algae. These data suggest that the digestive capabilities of L. undosum are better suited for assimilating organic material and nitrogen from less-preferred, non-kelp foods. This supports the hypothesis
that factors besides nutritional composition and digestive optimization have played a role in the evolution of feeding preferences
in L. undosum and probably other herbivorous snails associated with northeastern Pacific kelp beds. 相似文献
94.
A comparison of cat‐related risk perceptions and tolerance for outdoor cats in Florida and Hawaii
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Dara M. Wald Cheryl A. Lohr Christopher A. Lepczyk Susan K. Jacobson Linda J. Cox 《Conservation biology》2016,30(6):1233-1244
Risk perceptions and attitudes toward animals often explain tolerance for wildlife and management preferences. However, little is understood about how these relationships vary across different geographic regions and stakeholder groups. To address this gap in knowledge, we compared differences in acceptance capacity, risk perceptions, perceived enjoyment from outdoor cats, and experiences with outdoor cats among 3 groups (general public, conservation community, and animal‐welfare community) in Hawaii and Florida, two states with large conservation challenges. We combined independently collected data from Florida and Hawaii, to determine how perception of the risks presented by outdoor cats, group membership, and state of residence influenced people's tolerance for outdoor cats. Florida respondents were significantly more tolerant of outdoor cats and less concerned about cat‐related risks than Hawaii respondents (p < 0.05). In both states, animal‐welfare group members reported greater enjoyment seeing cats and perceived a smaller increase in the cat population and lower levels of risk than other groups (p < 0.05). All groups exhibited similar relationships between acceptance capacity and enjoyment and the perceived increase in the cat population. Our results suggest public tolerance for cats varied due to the influence of local or geographical concerns, but that strongly held beliefs, risk perceptions, and feelings about cats explained more of the variance in stakeholder tolerance. 相似文献
95.
96.
Andrew Fry Brad Adams Kevin Davis Dave Swensen Shawn Munson William Cox 《International Journal of Greenhouse Gas Control》2011
Real-time electrochemical measurements of corrosion rate were performed to evaluate the respective corrosion rates of one boiler waterwall material (SA210) and three boiler superheater materials (T22, P91 and 347H) while firing Utah Western bituminous, Illinois high-sulfur bituminous and Powder River Basin (PRB) sub-bituminous coals in a 1.5 MW pulverized coal-fired furnace. The raw average measured corrosion rates were very low, between 0.0003 and 0.016 mm/year (0.012 and 0.63 mils/year) for most materials under air- and oxy-fired conditions. For some high-sulfur conditions measured corrosion rates were as high as 0.72 mm/year (28 mils/year). Waterwall corrosion rates decreased consistently when converting from air- to oxy-firing while superheater corrosion rates generally increased, although they were less than twice the air-fired rate under most conditions. Corrosion rates for the lower alloyed materials (SA210 and T22) increased significantly during transients from reducing to oxidizing conditions. Measured increases in the corrosion rate of 347H material under high sulfur and low temperature conditions, and associated decrease in corrosion rate at higher temperatures on this alloy, were consistent with the formation of trisulphates in the superheater deposits. The increase of corrosion rate with increased metal temperatures was demonstrated, as was the consistently repeatable nature of the observed results. 相似文献
97.
Pesticide Risk Indicators: Unidentified Inert Ingredients Compromise Their Integrity and Utility 总被引:1,自引:0,他引:1
Pesticide Risk Indicators (PRIs) are widely used to evaluate and compare the potential health and environmental risks of pesticide
use and to guide pest control policies and practices. They are applied to agricultural, landscape and structural pest management
by governmental agencies, private institutions and individuals. PRIs typically assess only the potential risks associated
with the active ingredients because, with few exceptions, pesticide manufacturers disclose only the identity of the active
ingredients which generally comprise only a minor portion of pesticide products. We show that when inert ingredients are identified
and assessed by the same process as the active ingredient, the product specific risk can be much greater than that calculated
for the active ingredient alone. To maintain transparency in risk assessment, all those who develop and apply PRIs or make
decisions based on their output, should clearly disclose and discuss the limitations of the method. 相似文献
98.
Marrs RH Galtress K Tong C Cox ES Blackbird SJ Heyes TJ Pakeman RJ Le Duc MG 《Journal of environmental management》2007,85(4):1034-1047
Conservation management in Europe is often geared towards restoring semi-natural ecosystems, where the objective is to reverse succession and re-establish early-successional communities, to comply with national and international conservation targets. At the same time, it is increasingly recognised that ecosystems provide services that contribute to other, possibly conflicting policy requirements. Few attempts have been made to define these conflicts. Here, we assess some potential conflicts using a Calluna vulgaris-dominated moorland invaded by bracken (Pteridium aquilinum) as a model system, where the current policy is to reverse this process and restore moorland. We examined impacts of bracken control treatments on services (stocks and losses of C and mineral nutrients), litter turnover and biodiversity within a designed experiment over 7 years. Bracken litter was >2000 g m(-2) in untreated plots, and treatments reduced this quantity, and its element content, to varying degrees. Cutting twice per year was the most successful treatment in reducing bracken litter and its element content, increasing litter turnover, and increasing both mass and diversity of non-bracken vegetation. Diversity was greatest where bracken litter had been reduced, but species composition was also influenced by light sheep grazing. There was a significant loss of some chemical elements from bracken that could not be accounted for in other pools, and hence potentially lost from the system. In absolute terms large amounts of C and N were lost, but when expressed as a percentage of the total amount in the system, Mg was potentially more important with losses of almost a third of the Mg in the surface soil-vegetation system. There is, therefore, a potential dilemma between controlling a mid-successional invasive species for conservation policy objectives, especially when that species has evolved to sequester nutrients, and the negative effect of increasing environmental costs in terms of carbon accounting required, the potential input of nutrients to aquatic systems, and long-term nutrient loss. There is, therefore, a need to balance conservation goals against potential damage to biogeochemical structure and function. 相似文献
99.
The Biogeography of Faunal Place Names in the United States 总被引:1,自引:0,他引:1
100.
N. J. Brown R. Cox R. Pakeman A. G. Thomson R. A. Wadsworth M. Yates 《Journal of Coastal Conservation》2002,8(1):55-60
Very high resolution imagery from an airborne multi-spectrål scanner has been used to estimate the distribution of different salt-marsh communities along a 30-km stretch of the North Norfolk coast. Field observations have been used to develop a mathematical relationship between the vegetation, physical environment and sediment accumulation. This relationship has been used to produce provisional sediment accretion maps for the north Norfolk coast. 相似文献