Sectoral approaches to improve regional carbon budgets     

Pete Smith  Gert-Jan Nabuurs  Ivan A. Janssens  Stefan Reis  Gregg Marland  Jean-François Soussana  Torben R. Christensen  Linda Heath  Mike Apps  Vlady Alexeyev  Jingyun Fang  Jean-Pierre Gattuso  Juan Pablo Guerschman  Yao Huang  Esteban Jobbagy  Daniel Murdiyarso  Jian Ni  Antonio Nobre  Changhui Peng  Adrian Walcroft  Shao Qiang Wang  Yude Pan  Guang Sheng Zhou 《Climatic change》2008,88(3-4):209-249

Humans utilise about 40% of the earth’s net primary production (NPP) but the products of this NPP are often managed by different sectors, with timber and forest products managed by the forestry sector and food and fibre products from croplands and grasslands managed by the agricultural sector. Other significant anthropogenic impacts on the global carbon cycle include human utilization of fossil fuels and impacts on less intensively managed systems such as peatlands, wetlands and permafrost. A great deal of knowledge, expertise and data is available within each sector. We describe the contribution of sectoral carbon budgets to our understanding of the global carbon cycle. Whilst many sectors exhibit similarities for carbon budgeting, some key differences arise due to differences in goods and services provided, ecology, management practices used, land-management personnel responsible, policies affecting land management, data types and availability, and the drivers of change. We review the methods and data sources available for assessing sectoral carbon budgets, and describe some of key data limitations and uncertainties for each sector in different regions of the world. We identify the main gaps in our knowledge/data, show that coverage is better for the developed world for most sectors, and suggest how sectoral carbon budgets could be improved in the future. Research priorities include the development of shared protocols through site networks, a move to full carbon accounting within sectors, and the assessment of full greenhouse gas budgets.  相似文献   

Graphite oxidation in the Apollo 17 orange glass magma: Implications for the generation of a lunar volcanic gas phase     

Mike G. Nicholis  Malcolm J. Rutherford   《Geochimica et cosmochimica acta》2009,73(19):5905-5917

An Apollo 17 picritic orange glass composition has been used to experimentally investigate the conditions at which graphite would oxidize to form a CO-rich gas, and ultimately produce lunar fire-fountain eruptions. Isothermal decompression experiments run above the A17 orange glass liquidus temperature (>1350 °C) suggest that the initial CO-rich gas phase produced by graphite oxidation would be generated during magma ascent at a pressure of 40 MPa, 8.5 km beneath the lunar surface. Additional experiments with 2000 ppm S and 1000 ppm Cl showed that the presence of these dissolved gas species would not affect the depth of graphite oxidation, verifying that the first volcanic gas phase would be generated by the oxidation of graphite.A simple ideal chemical mixing model for calculating melt FeO activity in a Fe-metal/silicate melt system was tested with a series of 0.1 MPa controlled oxygen fugacity experiments. Agreement between the model and experiments allows the model to be used to calculate oxygen fugacity in picritic lunar glass compositions such as the A17 orange glass. Using this model in a reanalysis of chemical equilibria between the natural A17 orange glass melt and the metal spherules (Fe₈₅Ni₁₄Co₁) trapped within the glass beads indicates a log oxygen fugacity of −11.2, 0.7 log units, more oxidized than previous estimates. At the A17 orange glass liquidus temperature (1350 ± 5 °C), this f_O2 corresponds to a minimum pressure of 41 MPa on the graphite–C–O surface. The fact that the same critical graphite oxidation pressure was determined in decompression experiments and from the Fe–FeO activity model for the natural A17 orange glass–metal assemblage strongly supports this pressure (8.5 km depth) for volcanic gas formation in lunar basalts. Generation of a gas by oxidation of C in ascending magma is likely to have been important in getting dense lunar magmas to the surface as well as in generating fire-fountain eruptions. The vesicles common in many lunar basalts and the ubiquitous Fe-metal in these rocks are also likely generated by the oxidation of carbon. The presence of carbon in the lunar basalts and the recent discovery of ppm levels of water in lunar basalts indicate that at least parts of the lunar interior still contained volatiles at 3.9 bybp.  相似文献   

Calcrete formation and implications for buried archaeological deposits in the Mariana Islands,western Pacific     

Mike T. Carson  John A. Peterson 《Geoarchaeology》2011,26(4):501-513

Calcrete zones of cemented sands are found repeatedly at beach sites in the Mariana Islands, western Pacific region, with mid‐ to late‐Holocene artifacts and midden sealed within and beneath these layers. Three site‐specific cases demonstrate that the cementation process of the calcareous sand material post‐dated the deposition of artifacts and midden. Archaeological efforts must be prepared for deep excavation through zones of cemented sand. Also, recovery of preserved ancient materials can proceed by excavating large hardened blocks and soaking in light (5%) acid. This knowledge about formation process and recovery technique may prove useful not only in the Mariana Islands but also more broadly in other regions with similar settings. © 2011 Wiley Periodicals, Inc.  相似文献   

Interstellar heliospheric probe/heliospheric boundary explorer mission—a mission to the outermost boundaries of the solar system     

Robert F. Wimmer-Schweingruber  Ralph McNutt  Nathan A. Schwadron  Priscilla C. Frisch  Mike Gruntman  Peter Wurz  Eino Valtonen 《Experimental Astronomy》2009,24(1-3):9-46

The Sun, driving a supersonic solar wind, cuts out of the local interstellar medium a giant plasma bubble, the heliosphere. ESA, jointly with NASA, has had an important role in the development of our current understanding of the Suns immediate neighborhood. Ulysses is the only spacecraft exploring the third, out-of-ecliptic dimension, while SOHO has allowed us to better understand the influence of the Sun and to image the glow of interstellar matter in the heliosphere. Voyager 1 has recently encountered the innermost boundary of this plasma bubble, the termination shock, and is returning exciting yet puzzling data of this remote region. The next logical step is to leave the heliosphere and to thereby map out in unprecedented detail the structure of the outer heliosphere and its boundaries, the termination shock, the heliosheath, the heliopause, and, after leaving the heliosphere, to discover the true nature of the hydrogen wall, the bow shock, and the local interstellar medium beyond. This will greatly advance our understanding of the heliosphere that is the best-known example for astrospheres as found around other stars. Thus, IHP/HEX will allow us to discover, explore, and understand fundamental astrophysical processes in the largest accessible plasma laboratory, the heliosphere.  相似文献   

The 6dF Galaxy Survey: final redshift release (DR3) and southern large-scale structures     

D. Heath Jones  Mike A. Read  Will Saunders  Matthew Colless  Tom Jarrett  Quentin A. Parker  Anthony P. Fairall †  Thomas Mauch  Elaine M. Sadler  Fred G. Watson  Donna Burton  Lachlan A. Campbell  Paul Cass  Scott M. Croom  John Dawe †  Kristin Fiegert  Leela Frankcombe  Malcolm Hartley  John Huchra  Dionne James  Emma Kirby  Ofer Lahav  John Lucey  Gary A. Mamon  Lesa Moore  Bruce A. Peterson  Sayuri Prior  Dominique Proust  Ken Russell  Vicky Safouris  Ken-ichi Wakamatsu  Eduard Westra  Mary Williams 《Monthly notices of the Royal Astronomical Society》2009,399(2):683-698

We report the final redshift release of the 6dF Galaxy Survey (6dFGS), a combined redshift and peculiar velocity survey over the southern sky  (| b | > 10°)  . Its 136 304 spectra have yielded 110 256 new extragalactic redshifts and a new catalogue of 125 071 galaxies making near-complete samples with  ( K , H , J , r _F, b _J) ≤ (12.65, 12.95, 13.75, 15.60, 16.75)  . The median redshift of the survey is 0.053. Survey data, including images, spectra, photometry and redshifts, are available through an online data base. We describe changes to the information in the data base since earlier interim data releases. Future releases will include velocity dispersions, distances and peculiar velocities for the brightest early-type galaxies, comprising about 10 per cent of the sample. Here we provide redshift maps of the southern local Universe with   z ≤ 0.1  , showing nearby large-scale structures in hitherto unseen detail. A number of regions known previously to have a paucity of galaxies are confirmed as significantly underdense regions. The URL of the 6dFGS data base is http://www-wfau.roe.ac.uk/6dFGS .  相似文献   

Migration - why doesn't it work for deep continental data?     

Mike Warner 《Geophysical Journal International》1987,89(1):21-26

Summary. Conventional migration of deep seismic reflection data often produces disappointingly poor results even when the original unmigrated data are of high quality and are relatively noise free. Surprisingly, deep data often subjectively appear to be best migrated at velocities which are up to 50% less than appropriate interval velocities derived from crustal refraction experiments or directly from stacking velocities. The explanation for this behaviour is that near surface features distort and attenuate the seismic wave field and produce apparent discontinuities in deep reflections. Since these discontinuities are spurious they are not associated with the appropriate large diffractions which real discontinuities at depth would produce. During the process of migration reflections are invented in order to cancel out the missing diffractions thereby producing a "smiley" section which appears overmigrated. Since the lateral extent of individual smiles increases with increasing migration velocity, increasing two-way-time, and increasing seismic wavelength, the effect" is almost unnoticeable on conventional shallow seismic data but is overwhelming for deep crustal data.  相似文献   

The Palaeoproterozoic Kangerluluk gold–copper mineralization (southeast Greenland): Pb and Nd isotopic constraints on its timing and genesis     

Henrik Stendal  Robert Frei  Mike A. Hamilton  Wulf U. Mueller 《Mineralium Deposita》2001,36(2):177-188

The Ketilidian Mobile Belt (KMB) in South Greenland is dominated by the Palaeoproterozoic Julianehåb Batholith (1,850–1,770?Ma) and is bordered by supracrustal sequences. The batholith is composed of granite, granodiorite, tonalite, diorite and subordinate gabbro and appinite and formed in a juvenile magmatic arc. The supracrustal rocks consist of psammites, pelites and subordinate, interstratified mafic volcanic rocks. A Rapakivi granite suite (1,755–1,735?Ma) intrudes them. Gold is an important metal in the KMB and occurs in various settings and element associations. Here, emphasis is placed on the Kangerluluk Cu–Au mineralization in the eastern part of the mobile belt. It is hosted within a remnant supracrustal succession dominated by redundant pillowed basalts. Structurally, a syn-volcanic association with gold can be distinguished from one that is clearly related to crosscutting quartz veins. In between, calc-silicate formation in the volcanic rocks occurred contemporaneously with a pervasive sericitization (bleaching) of leucocratic granitoids that are intrusive into the volcanic sequence. Bulk rock and mineral (sulfide) Pb isotope data are comparable in the Pb isotope space. The data define two groups of mineralization where one group is characterized by relatively higher ²⁰⁷Pb/²⁰⁴Pb at given ²⁰⁶Pb/²⁰⁴Pb ratios than the other. Pb stepwise leaching (PbSL) dating experiments performed on garnet and epidote associated with both groups of mineralization confirm the offset in the Pb isotope data. With the geochronological information from PbSL, the results indicate: (1) the initial gold mineralization was genetically related to metalliferous fluids associated with the emplacement of late intrusive stages of the Julianehåb Batholith (1,800–1,770?Ma); and (2) local remobilization of the initial mineralization (1,700–1,750) involved a Pb isotopically evolved fluid, which tentatively can be correlated with the intrusion of the Rapakivi granites in the area. Radiogenic Pb was not only found in altered host rocks but also in various sulfides, suggesting that fluids may have percolated through and/or originated from uranium-bearing graphitic schists which are abundant in the sedimentary package of the KMB. Lead isotopic results suggest that the Rapakivi granites may have supplied heat for renewed circulation of fluids within the supracrustal rock pile.  相似文献   

Hydrochemical and stable isotope evidence for the extent and nature of the effective Chalk aquifer of north Norfolk, UK     

K. M. Hiscock  P. F. Dennis  P. R. Saynor  M. O. Thomas 《Journal of Hydrology》1996,180(1-4):79-107

In eastern England the Chalk aquifer is covered by extensive Pleistocene deposits which influence the hydraulic conditions and hydrochemical nature of the underlying aquifer. In this study, the results of geophysical borehole logging of groundwater temperature and electrical conductivity and depth sampling for major ion concentrations and stable isotope compositions (δ¹⁸O and δ²H) are interpreted to reveal the extent and nature of the effective Chalk aquifer of north Norfolk. It is found that the Chalk aquifer can be divided into an upper region of fresh groundwater, with a Cl concentration of typically less than 100 mg l⁻¹, and a lower region of increasingly saline water. The transition between the two regions is approximately 50 m below sea-level, and results in an effective aquifer thickness of 50–60 m in the west of the area, but less than 25 m where the Eocene London Clay boundary is met in the east of the area. Hydrochemical variations in the effective aquifer are related to different hydraulic conditions developed in the Chalk. Where the Chalk is confined by low-permeability Chalky Boulder Clay, isotopically depleted groundwater (δ¹⁸O less than −7.5‰) is present, in contrast to those areas of unconfined Chalk where glacial deposits are thin or absent (δ¹⁸O about −7.0‰). The isotopically depleted groundwater is evidence for groundwater recharge during the late Pleistocene under conditions when mean surface air temperatures are estimated to have been 4.5°C cooler than at the present day, and suggests long groundwater residence times in the confined aquifer. Elevated molar Mg:Ca ratios of more than 0.2 resulting from progressive rock-water interaction in the confined aquifer also indicate long residence times. A conceptual hydrochemical model for the present situation proposes that isotopically depleted groundwater, occupying areas where confined groundwater dates from the late Pleistocene, is being slowly modified by both diffusion and downward infiltration of modem meteoric water and diffusive mixing from below with an old saline water body.  相似文献   

Testing candidate indicators to support ecosystem-based management: the power of monitoring surveys to detect temporal trends in fish community metrics   总被引：3，自引：8，他引：3  

Nicholson  Mike D; Jennings  Simon 《ICES Journal of Marine Science》2004,61(1):35-42

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Ecological impacts of air pollution from road transport on local vegetation     

Keeley L. Bignal  Mike R. Ashmore  Alistair D. Headley  Kirstin Stewart  Katherina Weigert 《Applied Geochemistry》2007

Motor vehicles emit a cocktail of pollutants and are a major contributor to ground-level air pollution, but little is known regarding the ecological impacts of air pollution from roads on the surrounding vegetation. Data are presented on vegetation at three sites adjacent to two major motorways in the UK, comprising two woodland sites and one blanket bog site. Surveys of oak and beech tree health (at the woodland sites) and species composition (at the blanket bog site) were undertaken along transects away from the motorway.  相似文献