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Mapping global forest biomass and its changes over the first decade of the 21st century

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Science China Earth sciences 2019年第3期62卷 585-594页

作者： Anping CHEN Shushi PENG Songlin FEI department of Forestry and Natural Resources Purdue University The Woods Hole Research Center laboratoire des sciences du climat et de l'environnement(lSCE) CEA-CNRS-UVSQ

Forests played an important role in carbon sequestration during the past two decades. Using a model tree ensemble method(MTE) to regress the seven reflectance bands of EOS-Terra-MODIS satellite data against country level forest biomass carbon density(BCD) of 2001–2005 provided by United Nations' s Forest Resource Assessment(FRA), we developed a global map of forest BCD at 1 km×1 km resolution for both 2001–2005 and 2006–2010. For 2006–2010, the total global forest biomass carbon stock is estimated as 279.6±7.1 Pg C, and the tropical forest biomass carbon stock is estimated as 174.4±5.4 Pg C. during the first decade of the 21 st century, we estimated an increase of global forest biomass of 0.28±0.75 Pg C yr^(-1). Tropical forest biomass carbon stock slightly decreased(-0.31±0.60 Pg C yr^(-1)); by contrast, temperate and boreal forest biomass increased(0.58±0.28 Pg C yr^(-1)) during the same period. Our estimation of the global forest biomass carbon stock and its changes is subject to uncertainties due to lack of extensive ground measurements in the tropics, spatial heterogeneity in large countries, and different definitions of forest. The continuously monitoring of forest biomass carbon stock with MODIS satellite data will provide useful information for detecting forest changes.

关键词： Forest biomass Carbon stock Model tree ensemble(MTE) MODIS Remote sensing

Sediment fingerprinting in fluvial systems:review of tracers,sediment sources and mixing models

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International Journal of Sediment Research 2013年第4期28卷 560-578页

作者： Arman HADDADCHI Darren S.RYdeR Olivier EVRARD Jon OllEY Australian Rivers Institute Griffith University School of Environmental and Rural sciences University of New England laboratoire des sciences du climat et de l'environnement(lSCE/IPSl)

Suspended sediments in fluvial systems originate from a myriad of diffuse and point sources,with the relative contribution from each source varying over time and *** process of sediment fingerprinting focuses on developing methods that enable discrete sediment sources to be identified from a composite sample of suspended *** review identifies existing methodological steps for sediment fingerprinting including fluvial and source sampling,and critically compares biogeochcmical and physical tracers used in fingerprinting *** of applying different mixing models to the same source data are explored using data from 41 catchments across Europe,Africa,Australia,Asia,and North and South *** application of seven commonly used mixing models to two case studies from the US(North Fork Broad River watershed) and France(BIcone watershed) with local and global(genetic algorithm) optimization methods identified all outputs remained in the acceptable range of error defined by the original *** propose future sediment fingerprinting studies use models that combine the best explanatory parameters provided by the modified Collins(using correction factors) and Hughes(relying on iterations involving all data,and not only their mean values) models with optimization using genetic algorithms to best predict the relative contribution of sediment sources to fluvial systems.

关键词： watershed fluvial sampling source tracing modeling local optimization genetic algorithm

Evolution of heat transport pathways in the Indonesian Archipelago during last deglaciation

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Chinese Science Bulletin 2002年第22期47卷 1912-1917页

作者： F.Guichard F.Bassinot l.labeyrie China University of Geosciences (Beijing) Beijing China laboratoire des sciences du climat et de l’environnement Domaine du CNRS Gif-sur-Yvette France

The Indonesian Archipelago provides important heat transport pathways of the Western Pacific Warm Pool between the northern Indian Ocean and western equatorial Pacific Ocean, that exert important impacts on global climate change. This study investigated AMS 14C, δ18O, planktonic foraminifer assemblages and sedimentation rates in three piston cores collected in the Indonesian Archipelago. The results indicate that changes in the Indonesian Archipelago heat transport pathways were phase characteristic and in steps during the last deglaciation. In the deglaciation Termination IA, at about 12.5 kaBP, sea level rose rapidly in a short time period, and Makassar and lombok straits widened suddenly for warm and fresh water from the Pacific to pour into the Java Sea and eastern Indian Ocean. during the Termination IB, about 9.5 kaBP, sea level rose rapidly again, and the South China Sea (SCS) started to connect with the Java Sea. With monsoon actions, a large amount of fresh water from the SCS shelf area flew

关键词： Indonesian Archipelago last deglaciation heat transport pathways β18O planktonic foraminifer assemblages.

The B/Ca and Cd/Ca of a subsurface-dwelling foraminifera Pulleniatina obliquiloculata in the tropical Indo-Pacific Ocean: implications for the subsurface carbonate chemistry estimation

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Acta Oceanologica Sinica 2019年第3期38卷 138-150页

作者： Haowen Dang Tingting Wang Peijun Qiao Franck Bassinot Zhimin Jian State Key laboratory of Marine Geology Tongji University laboratoire des sciences du climat et de l'environnement/IPSl CEA-CNRS-UVSQ Université Paris-Saclay

Pulleniatina obliquiloculata shells from 16 core-top samples from the tropical Indo-Pacific Oceans are analyzed for the ratios of boron and cadmium to calcium(B/Ca and Cd/Ca). The B/Ca ratios show a very weak positive relationship with [B(OH)_4^-] and the dissolved carbonate species at the apparent calcification depth of ***. The boron partition coefficients(K_D) between P. obliquiloculata B/Ca and seawater[B(OH)_4^-]/[HCO_3^-] distribute around 1.1×10^(-3)-1.3×10^(-3) with a mean value of(1.19±0.12)×10^(-3),and are significantly related to the nutrient concentration, especially phosphate. The lack of any clear correlation between the P. obliquiloculata B/Ca and seawater carbonate chemical parameters suggests that the physiochemical controls on boron incorporation are masked by the complexity of natural seawater condition. But the significant dependence of Ku on nutrient may likely be explained by a nutrient related growth-rate effect. Cd/Ca of *** shows significant correlation with seawater phosphate concentration, and its partition coefficients(D_(cd)) are significantly related to temperature. A first-principle methodology of P. obliquiloculata B/Ca is applied;with the aid of Cd/Ca as a phosphate proxy and a constraint on K_D, to estimating sea water carbonate chemistry(e.g., pH). The results are fairly promising and allow us to propose the possibility to apply the combination of B/Ca and Cd/Ca proxies(and also Mg/Ca and δ^(18)O for estimating temperature and salinity) for the paleoreconstruction of seawater carbonate chemistry.

关键词： Pulleniatina obliquiloculata B/Ca Cd/Ca paleo-pH estimation

Soil and vegetation water content identify the main terrestrial ecosystem changes

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National Science Review 2023年第5期10卷 167-179页

作者： Diego Bueso Maria Piles Philippe Ciais Jean-Pierre Wigneron álvaro Moreno-Martínez Gustau Camps-Valls Image Processing laboratory Universitat de València laboratoire des sciences du climat et de l'environnement Université Paris Saclay INRA Centre de Bordeaux Aquitaine Image Processing laboratory Universitat deValència

Environmental change is a consequence of many interrelated *** vegetation responds to natural and human activity still needs to be well establishe d,quantified and *** cent satellite missions providing hydrologic and ecological indicators enable better monitoring of Earth system changes,yet there is no automatic way to address this issue directly from ***,we develop an observation-based methodology to capture evidence of changes in global terrestrial ecosystems and attribute these changes to natural or anthropogenic *** use the longest time record of global microwave l-band soil moisture and vegetation optical depth as satellite data and build spatially explicit maps of change in soil and vegetation water content and biomass reflecting large ecosystem changes during the last decade,*** of prominent trends(from-8% to 9% per year) are observed,especially in humid and semi-arid *** further combine such trends with land cover change maps,vegetation greenness and precipitation variability to assess their relationship with major documented ecosystem *** regions emerge from our *** cluster changes according to human activity drivers,including deforestation(Amazon,Central Africa) and wildfires(East Australia),artificial reforestation(South-East China),abandonment of farm fields(Central Russia) and climate shifts related to changes in precipitation variability(East Africa,North America and Central Argentina).Using the high sensitivity of soil and vegetation water content to ecosystem changes,microwave satellite observations enable us to quantify and attribute global vegetation responses to climate or anthropogenic activities as a direct measure of environmental changes and the mechanisms driving them.

关键词： soil moisture vegetation water content ecosystem trend remote sensing soil moisture and ocean salinity satellite

Characteristics of Carbonaceous Particles in Beijing during Winter and Summer 2003

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Advances in Atmospheric sciences 2006年第3期23卷 468-473页

作者：于建华陈添 Benjamin GUINOT Helene CACHIER 虞统刘文清王欣 Beijing Municipal Environmental Monitoring Center labomtoire des sciences du climat et de l'Environment Anhui Institute of Optics and Fine Mechanics

Campaigns were conducted to measure Organic Carbon （OC） and Elemental Carbon （EC） in PM2.5 during winter and summer 2003 in Beijing. Modest differences of PM2.5 and PM10 mean concentrations were observed between the winter and summer campaigns. The mean PM2.5/PM10 ratio in both seasons was around 60%, indicating PM2.5 contributed significantly to PM10. The mean concentrations of OC and EC in PM2.5 were 11.2±7.5 and 6.0±5.0 μg m^-3 for the winter campaign, and 9.4±2.1 and 4.3±3.0 μg m^-3 for the summer campaign, respectively. Diurnal concentrations of OC and EC in PM2.5 were found high at night and low during the daytime in winter, and characterized by an obvious minimum in the summer afternoon. The mean OC/EC ratio was 1.87±0.09 for winter and 2.39±0.49 for summer. The higher OC/EC ratio in summer indicates some formation of Secondary Organic Carbon （SOC）. The estimated SOC was 2.8 μg m^-3 for winter and 4.2 μg m^-3 for summer.

关键词： elemental carbon organic carbon PM2.5 PM10 secondary organic carbon

Observations of contrasted glacial-interglacial dissolution of foraminifera above the lysocline in the Bay of Bengal,northeastern Indian Ocean

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Acta Oceanologica Sinica 2021年第1期40卷 155-161页

作者： duo Wang Xuan Ding Franck Bassinot School of Ocean sciences China University of Geosciences(Beijing)Beijing 100083China laboratoire des sciences du climat et de l’environnement National Agency for Nuclear Energy/National Centre for Scientifique Research/University of Versailles-Saint QuentinGif-sur-Yvette 91198France

Site U1446(19°50’N,85°44’E,at water depth 1430 m)was drilled during Expedition 353(Indian monsoon rainfall)of the International Ocean Discovery Program(IODP).It is located in the Mahanadi offshore basin,on the northern Bay of *** rates and contents of biocarbonates are high at this relatively shallow *** a micropaleontological approach,we examined planktonic and benthic foraminifera in the upper around 40 m of this site,spanning the last around 190 ka.A striking feature of the foraminiferal record is the occurrence of strong but varying dissolution although the site is located well above the modern *** strong dissolution has never been reported in this *** estimated the flux of foraminifera and quantified the ratio of benthic foraminifera over total foraminifera(benthic/total foraminifera)along with the foraminifer fragmentation index in order to characterize past changes in this above-lysocline *** study reveals a clear glacialinterglacial contrast,with a stronger dissolution during marine isotope stages(MISs)1 and 5 than during MISs 2–4 and *** a difference in preservation is likely to have a strong impact on geochemical proxies measured on *** new observations call for an in-depth study of the causes of such above-lysocline dissolution in the region,and an evaluation of its impact on the foraminifera-based proxies used for paleoenvironmental reconstruction.

关键词： foraminifera dissolution lysocline glacial-interglacial Bay of Bengal

Enhanced dielectric performance of Dy-substituted YMn2O5 for high-frequency applications

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Progress in Natural Science:Materials International 2021年第5期31卷 762-771页

作者： H.Chouaibi K.Khirouni E.Dhahri laboratoire de Physique Appliquée Faculté des Sciences Université de Sfax laboratoire de Physique des Matériaux et des Nanomatériaux Appliquée à l'environnement Faculté des Sciences de Gabès Cité Erriadh Université de Gabès

The dielectric performances as well as the effects of Dy3+ions content at A sites of YMn2O5(YMO) [x=0(YDM0)and x=0.4(YDM0.4)] polycrystalline samples were *** compounds were synthesized via sol-gel method.X-Ray diffraction and Raman measurements proved the high quality of the compounds that crystallized in an orthorhombic structure with the Pbam space ***,impedance spectroscopy and electrical modulus studies revealed that both samples exhibited a non-debye’s type of *** decrease of impedance for YDM0.4compared to the pure YDM0,may be attributed to the decrease in charge transfer *** the fit of impedance spectra,they confirmed that both compounds were simultaneously capacitive and ***,the activation energies obtained from Modulus and complex impedance were proven to be neighboring,suggesting that the relaxation process refers to electron *** each compound,the evolution of ε’and tan & with temperature indicated a clearer relaxor behavior,namely the existence of two *** first one detected at low temperature is related to the charge carriers hopping between Mn3+and Mn4+and the second at high temperature is associated with oxygen *** reduced hopping rate with Dy3+substitution for Y3+ions at A sites is responsible for the decrease in dielectric constant and dielectric *** significant findings demonstrate that these materials can be invested in a fruitful use in UV photo-detector and power applications in high frequency as microwave,millimeter wave signal processing,for civilian,military and space applications.

关键词： Multiferroic Relaxation phenomenon High dielectric constant Relaxor behavior

Clay mineral records of East Asian monsoon evolution during late Quaternary in the southern South China Sea

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Science China Earth sciences 2005年第1期48卷 84-92页

作者： C.Colin A.Trentesaux D.Blamart FRE 2566 Orsaylerre UMR PBDS du CNRSLaboratoire des Sciences du Climat et de I'Environnement Université de Paris XI91405 OrsayFranceUniversite de Lille I59655 Villeneuve d'AscqFranceLaboratoire mixte CNRS-CEA91198 Gif-sur-YvetteFrance

High-resolution clay mineral records combined with oxygen isotopic stratigraphy over the past 190 ka during late Quaternary from core MD01-2393 off the Mekong River in the southern South China Sea are reported to reconstruct a history of East Asian monsoon *** dominating clay mineral components indicate a strong glacial-interglacial cyclicity, with high glacial illite, chlorite, and kaolinite contents and high interglacial smectites content. The provenance analysis indicates the direct input of clay minerals via the Mekong River drainage *** and chlorite derived mainly from the upper reach of the Mekong River, where physical erosion of meta-sedimentary rocks is dominant. Kaolinite derived mainly from active erosion of inhered clays from reworked sediments in the middle reaches. Smectites originated mainly through bisiallitic soils in the middle to lower reaches of the Mekong River. The smectites/(illite+chlorite)and smectites/kaolinite ratios are determined as mineralogical indicators of East Asian monsoon variations. Relatively high ratios occur during interglacials and indicate strengthened summer-monsoon rainfall and weakened winter-monsoon winds; relatively lower ratios happened in glacials, indicating intensified winter monsoon and weakened summer monsoon. The evolution of the summer and winter monsoons provides an almost linear response to the summer insolation of the Northern Hemisphere, implying an astronomical forcing of the East Asian monsoon evolution.

关键词： clay minerals, East Asian monsoon, late Quaternary, Mekong River, South China Sea.