The climatic impacts of land surface change and carbon management, and the implications for climate-change mitigation policy   总被引：4，自引：0，他引：4  

Gregg Marland  Roger A. Pielke Sr. 《Climate Policy》2003,3(2):149-157

Strategies to mitigate anthropogenic climate change recognize that carbon sequestration in the terrestrial biosphere can reduce the build-up of carbon dioxide in the Earth’s atmosphere. However, climate mitigation policies do not generally incorporate the effects of these changes in the land surface on the surface albedo, the fluxes of sensible and latent heat to the atmosphere, and the distribution of energy within the climate system. Changes in these components of the surface energy budget can affect the local, regional, and global climate. Given the goal of mitigating climate change, it is important to consider all of the effects of changes in terrestrial vegetation and to work toward a better understanding of the full climate system. Acknowledging the importance of land surface change as a component of climate change makes it more challenging to create a system of credits and debits wherein emission or sequestration of carbon in the biosphere is equated with emission of carbon from fossil fuels. Recognition of the complexity of human-caused changes in climate does not, however, weaken the importance of actions that would seek to minimize our disturbance of the Earth’s environmental system and that would reduce societal and ecological vulnerability to environmental change and variability.  相似文献   

Images in weather forecasting: M.J. Bader, G.S. Forbes, J.R. Grant, R.B.E. Lilley and A.J. Waters (Editors), Cambridge University Press, Cambridge, UK, 1995, hardcover, ISBN 0-521-45111-6.     

Roger A. Pielke 《Dynamics of Atmospheres and Oceans》1997,25(4):279-280

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The respiratory environment of the Namib Desert Golden Mole     

Roger S. Seymour  Mary K. Seely 《Journal of Arid Environments》1996,32(4):453-461

We measured the partial pressure of oxygen (PO₂) in the interstitial gas surrounding the sand-swimming Namib moleEremitalpa granti namibensis. At a sand temperature of 26 °C, which produced a nearly maximal rate of oxygen consumption, thePO₂near the noses of the animals averaged only 0·9 kPa (6·7 Torr) below the level in the free atmosphere. High oxygen availability was a result of the notably low metabolic rate in the 20 g mammals and the dry, porous and metabolically inactive nature of dune sand. A mathematical model indicated that normal mammals weighing 200 g or more could comfortably exist completely encased in dune sand. We concluded that the moles' small size and low metabolic rate are not adaptations to hypoxia or hypercapnia underground but are probably related to low food availability and the energetic cost of foraging in their desert environment.  相似文献   

Heavy metal retention in secondary precipitates from a mine rock dump and underlying soil, Dalarna, Sweden   总被引：7，自引：2，他引：7  

Zhixun Lin  Roger B. Herbert Jr. 《Environmental Geology》1997,33(1):1-12

This study investigates the retention of heavy metals in secondary precipitates from a sulfidic mine rock dump and underlying podzolic soils by means of mineralogical and chemical extraction methods. The rock dump, which is at least 50 years old, consists of a 5–10-cm-thick leached zone and an underlying 110–115-cm-thick accumulation zone. Optical microscopy and electron microprobe analyses confirm that pyrrhotite weathering has proceeded much further in the leached horizon relative to the accumulation horizon. The weathering of sulfides in the leached zone has resulted in the migration of most heavy metals to the accumulation zone or underlying soils, where they are retained in more stable phases such as secondary ferric minerals, including goethite and jarosite. Some metals are temporarily retained in hydrated ferrous sulfates (e.g., melanterite, rozenite). Received: 28 October 1996 · Accepted: 24 February 1997  相似文献   

Observations of borehole-source amplitude reduction due to casing     

Richard L. Gibson  Walter R. Turpening  rea Born  & Roger M. Turpening 《Geophysical Prospecting》1997,45(1):1-20

Theoretical results show that the amplitude of a borehole source is reduced when the well in which it is operated is cased and cemented. This reduction is a strong function of the formation velocity and is more weakly dependent on the direction of propagation of the wave travelling from source to receiver and on the diameter of the borehole itself. We have tested these predictions with data gathered in a cross-hole seismic experiment conducted in two stages in 1990 and 1991. The source and receivers were located in the MIT/Stech 1-21A and MIT/Burch 1-20B wells at the Earth Resources Laboratory (ERL) test site in Michigan (USA). Though the source well (MIT/Stech 1-21A) was uncased in 1990, a steel casing and cement were added prior to the collection of data in 1991. Several receiver positions were reoccupied to compare data collected with the source in open and cased holes. Using a velocity model for this area and borehole diameter measurements from a calliper log, a compensation factor can be computed that will adjust the data collected in 1991 to have amplitudes comparable to that collected in the first stage of the experiment. The accuracy of the results demonstrates the validity of the theory, which can be very useful in better understanding seismic waveforms recorded in cross-hole experiments.  相似文献   

Kinetics of the Gas-Phase Reactions of OH Radicals, NO3 Radicals and O3 with Three C7-Carbonyls Formed From The Atmospheric Reactions of Myrcene, Ocimene and Terpinolene     

Jillian Baker  Janet Arey  Roger Atkinson 《Journal of Atmospheric Chemistry》2004,48(3):241-260

Rate constants for the gas-phase reactions of OH radicals, NO₃ radicals and O₃ with the C₇-carbonyl compounds 4-methylenehex-5-enal [CH₂=CHC(=CH₂)CH₂CH₂CHO], (3Z)- and (3E)-4-methylhexa-3,5-dienal [CH₂=CHC(CH₃)=CHCH₂CHO] and 4-methylcyclohex-3-en-1-one, which are products of the atmospheric degradations of myrcene, Z- and E-ocimene and terpinolene, respectively, have been measured at 296 ± 2 K and atmospheric pressure of air using relative rate methods. The rate constants obtained (in cm³ molecule^–1 s^–1 units) were: for 4-methylenehex-5-enal, (1.55 ± 0.15) × 10^–10, (4.75 ± 0.35) × 10^–13 and (1.46 ± 0.12) × 10^–17 for the OH radical, NO₃ radical and O₃ reactions, respectively; for (3Z)-4-methylhexa-3,5-dienal: (1.61 ± 0.35) × 10^–10, (2.17 ± 0.30) × 10^–12, and (4.13 ± 0.81) × 10^–17 for the OH radical, NO₃ radical and O₃ reactions, respectively; for (3E)-4-methylhexa-3,5-dienal: (2.52 ± 0.65) × 10^–10, (1.75 ± 0.27) × 10^–12, and (5.36 ± 0.28) × 10^–17 for the OH radical, NO₃ radical and O₃ reactions, respectively; and for 4-methylcyclohex-3-en-1-one: (1.10 ± 0.19) × 10^–10, (1.81 ± 0.35) × 10^–12, and (6.98 ± 0.40) × 10^–17 for the OH radical, NO₃ radical and O₃ reactions, respectively. These carbonyl compounds are all reactive in the troposphere, with daytime reaction with the OH radical and nighttime reaction with the NO₃ radical being predicted to dominate as loss processes and with estimated lifetimes of about an hour or less.  相似文献   

Recent Progress and Future Prospects in Solar Physics, and Their Relevance for Planet Earth     

Roger M. Bonnet  Anuschka pauluhn 《Surveys in Geophysics》2004,25(5-6):371-440

Understanding our star, the Sun, is of fundamental interest for life on Earth. In this paper, the status of knowledge in solar physics of roughly two decades ago is summarised, and the most recent developments in this very active field are shown, many of them achieved by means of space based missions. The Sun–Earth connection is described and, finally, an outlook on future solar research is given.  相似文献   

An experimental study of the formation of metallic iron in chondrules     

Bosmat A Cohen  Roger H Hewins 《Geochimica et cosmochimica acta》2004,68(7):1677-1689

The abundance of metallic iron is highly variable in different kinds of chondrites. The precise mechanism by which metal fractionation occurred and its place in time relative to chondrule formation are unknown. As metallic iron is abundant in most Type I (FeO-poor) chondrules, determining under what conditions metal could form in chondrules is of great interest. Assuming chondrules were formed from low temperature nebular condensate, we heated an anhydrous CI-like material at 1580°C in conditions similar to those of the canonical nebula (P_H2 = 1.3 × 10⁻⁵ atm). We reproduced many of the characteristics of Type IA and IIA chondrules but none of them contained any iron metal. In these experiments FeO was abundant in charges that were heated for as long as 6 h. At a lower temperature, 1350°C, dendritic/cellular metal crystallized from Fe-FeS melts during the evaporation of S. However, the silicate portion consisted of many relict grains and vesicles, not typical of chondrules.Evaporation experiments conducted at P_H2 = 1 atm and 1565°C produced charges containing metallic iron both as melt droplets and inclusions in olivine, similar to those found in chondrules. Formation of iron in these experiments was primarily the result of desulfurization of FeS. With long heating times Fe° was lost by evaporation. Apart from some reduction of FeO by kerogen to make metal inclusions within olivine grains, reduction of FeO to make Fe° in these charges was not observed.This study shows that under canonical nebular conditions FeS and iron-metal are extremely volatile so that metal-rich Type I chondrules could not form by melting “CI.” Under these conditions FeO is lost predominantly by hydrogen stripping and, due to the relative low abundance of hydrogen at low pressures, remains in the melt for as long as 6 h. Conversely, at higher total pressures (1-atm H₂) iron metal (produced mainly by the desulfurization of troilite) is less volatile and remains in the melt for longer times (at least 6 h). In addition, due to elevated pressures of hydrogen, FeO is stripped away much faster. These results suggest that chondrule formation occurred in environments with elevated pressures relative to the canonical nebula for iron metal to be present.  相似文献   

Are the benches at Mormon Point, Death Valley, California, USA, scarps or strandlines?     

Roger LeB. Hooke 《Quaternary Research》2004,61(3):339-343

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Group photo Hawthorne volume     

Roger H. Mitchell   《Lithos》2004,77(1-4):xi-xiv

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