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191.
192.
Bernardo Strassburg R. Kerry Turner Brendan Fisher Roberto Schaeffer Andrew Lovett 《Global Environmental Change》2009,19(2):265-278
Despite accounting for 17–25% of anthropogenic emissions, deforestation was not included in the Kyoto Protocol. The UN Convention on Climate Change is considering its inclusion in future agreements and asked its scientific board to study methodological and scientific issues related to positive incentives to reduce emissions from deforestation. Here we present an empirically derived mechanism that offers a mix of incentives to developing countries to reduce emissions from deforestation, conserve and possibly enhance their ecosystem's carbon stocks. We also use recent data to model its effects on the 20 most forested developing countries. Results show that at low CO2 prices (~US$ 8/t CO2) a successful mechanism could reduce more than 90% of global deforestation at an annual cost of US$ 30 billion. 相似文献
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The excretion of photosynthetically fixed carbon from cultured marine diatoms and its influence on Cu, Zn and Cd complexation in seawater was studied for three species. For each species, an isolate from oligotrophic waters was compared with an estuarine isolate. Complexation of metal was determined with the use of differential pulse anodic stripping voltammetry. Excreted material from cells in log-phase growth complexed Cu > Zn > Cd, while material derived from senescent cells complexed only Zn. The filtrates of all cultures complexed these metals comparably with natural coastal seawater. There were no appreciable differences in complexing ability within or among species, suggesting that no excretion-complexation ‘strategy’ peculiar to each ecosystem exists among these species. 相似文献
196.
A multi-wavelength radar backscatter study of the echo characteristics of radio-meteors has yielded measurements of the height dependence of the radii, ri, of overdense plasma meteor columns. For electron line densities α ~ 1015 m?1 it is found that ri ∝ ??0.63 (? atmospheric density) with ri = 5 m at a height of 100 km. 相似文献
197.
Laboratory measurements are presented showing how a laser sand detector (LSD) can be used to discriminate between bubbles and sand, because sand depolarizes light, whereas bubbles do not. 相似文献
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An application of polynomial curve fitting to sediment cumulative frequency distributions is presented to delineate the foreshore depositional patterns along the barrier beaches of the Rhode Island southshore. The analysis is based on 92 sampled stations where data for beach geometry, tidal stage, and sediment size were collected. Using the size-frequency classes obtained from sieving the foreshore sediment samples at 0.25 O intervals and fitting third-degree polynomial equations to these data, over 94% of the variation within the sediment cumulative frequency distributions is explained. The four curve coefficients (a, b, c, d) derived from the predicted third-degree equation are used in a discriminant function analysis to test the relationship between the curve shape and sediment source. Comparison of the discriminant scores with the respective station locations suggests that a series of Pleistocene headlands which occur as discrete points along the beach are serving as independent sources of sediment for the system. 相似文献
200.
We present a series of numerical simulations of the quiet-Sun plasma threaded by magnetic fields that extend from the upper
convection zone into the low corona. We discuss an efficient, simplified approximation to the physics of optically thick radiative
transport through the surface layers, and investigate the effects of convective turbulence on the magnetic structure of the
Sun’s atmosphere in an initially unipolar (open field) region. We find that the net Poynting flux below the surface is on
average directed toward the interior, while in the photosphere and chromosphere the net flow of electromagnetic energy is
outward into the solar corona. Overturning convective motions between these layers driven by rapid radiative cooling appears
to be the source of energy for the oppositely directed fluxes of electromagnetic energy. 相似文献