2015年秋季我国气候异常及暖湿成因分析   总被引：5，自引：4，他引：1  

聂羽  孙冷  李清泉  马丽娟 《气象》2016,42(4):507-513

2015年秋季,全国平均气温较常年同期偏高,降水量偏多明显,为1951年以来同期第三高值,我国总体呈现“暖湿”的特征,但南北方降水特征有明显差异。受水汽条件不同的影响,华南地区为持续性降水,而华北表现为阵性降水。诊断分析表明,华南的持续性降水偏多与超强厄尔尼诺和赤道印度洋偏暖的共同作用有关。赤道东太平洋和赤道印度洋地区海温偏高,加强了西太平洋地区低层的反气旋环流异常,造成西太平洋副热带高压偏强偏西。受副热带高压西侧异常南风的引导,来自南海和西太平洋的异常水汽向华南输送,造成了秋季华南持续降水偏多。而受中高纬度环流经向度偏大的影响,冷空气在华北活跃,配合东路和南路水汽的阶段性输送,则造成了华北的降水偏多。  相似文献   

Constraints of molybdenite Re–Os and scheelite Sm–Nd ages on mineralization time of the Kukaazi Pb–Zn–Cu–W deposit,Western Kunlun,NW China     

Chengbiao Leng  Yuhui Wang  Xingchun Zhang  Jianfeng Gao  Wei Zhang  Xinying Xu 《中国地球化学学报》2018,37(1):47-59

The Kukaazi Pb–Zn–Cu–W polymetallic deposit, located in the Western Kunlun orogenic belt, is a newly discovered skarn-type deposit. Ore bodies mainly occur in the forms of lenses and veins along beddings of the Mesoproterozoic metamorphic rocks. Three ore blocks, KI, KII, and KIII, have been outlined in different parts of the Kukaazi deposit in terms of mineral assemblages. The KI ore block is mainly composed of chalcopyrite, scheelite, pyrrhotite, sphalerite, galena and minor pyrite, arsenopyrite, and molybdenite, whereas the other two ore blocks are made up of galena, sphalerite, magnetite and minor arsenopyrite and pyrite. In this study, we obtained a molybdenite isochron Re–Os age of 450.5 ± 6.4 Ma (2σ, MSWD = 0.057) and a scheelite Sm–Nd isochron age of 426 ± 59 Ma (2σ, MSWD = 0.49) for the KI ore block. They are broadly comparable to the ages of granitoid in the region. Scheelite grains from the KI ore block contain high abundances of rare earth elements (REE, 42.0–95.7 ppm) and are enriched in light REE compared to heavy REE, with negative Eu anomalies (δEu = 0.13–0.55). They display similar REE patterns and Sm/Nd ratios to those of the coeval granitoids in the region. Moreover, they also have similar Sr and Nd isotopes [⁸⁷Sr/⁸⁶Sr = 0.7107–0.7118; ε_Nd(t) = ?4.1 to ?4.0] to those of such granitoids, implying that the tungsten-bearing fluids in the Kukaazi deposit probably originate from the granitic magmas. Our results first defined that the Early Paleozoic granitoids could lead to economic Mo–W–(Cu) mineralization at some favorable districts in the Western Kunlun orogenic belt and could be prospecting exploration targets.  相似文献   

An Introduction of the Projects Managed by Division of Marine and Polar Sciences,Department of Earth Sciences,National Natural Science Foundation of China in 2018     

Leng Shuying  Li Wei  Li Keqiang  Sha Longbin  Sha Zhenxia  Sha Jin 《地球科学进展》2018,33(12):1305-1313

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Multi‐proxy study of Holocene environmental change and human activity in the Central Apennine Mountains,Italy     

A. G. Brown  J. Hatton  K. A. Selby  M. J. Leng  N. Christie 《第四纪科学杂志》2013,28(1):71-82

This paper describes a multi‐proxy palaeoecological investigation undertaken in conjunction with an archaeological survey of the Upper Sangro Valley in the Abruzzo National Park, Central Italy. Despite being a biodiversity hotspot and regarded as a near‐pristine area, the pollen, spore and diatom data all show major changes in the vegetation extending to over 2000 m a.s.l. during the mid to late Holocene. Although there are changes in ecological composition earlier in the Holocene they are different in type and magnitude from the changes which began about 800 cal a BC. The pollen and diatom evidence do not correlate well with regional palaeoclimate data, or on‐site isotopic evidence, but do appear to be related to Samnite (later Iron Age) clearance and upland grazing associated with transhumance and later annexation (and centuriation) of the lower slopes by Roman surveyors. The greatest change in vegetation was during the period c. AD 500–600 and corresponds with the Byzantine–Gothic Wars, and Lombard–Carolingian settlement reorganization into nucleated hilltop settlements which managed upland grazing. This pattern of intensive land use at all altitudes persisted until the early 20th century and only changed following rural depopulation after World War II. These data illustrate how cultural factors had a profound effect on this mountainous region which, in this case, far outweighed the effects of climatic fluctuations which are known to have occurred from both this study area and the region. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Evaluation of ostracod-based palaeoenvironmental reconstruction with instrumental data from the arid Faiyum Depression,Egypt     

K. W. Keatings  I. Hawkes  J. A. Holmes  R. J. Flower  M. J. Leng  R. H. Abu-Zied  A. R. Lord 《Journal of Paleolimnology》2007,38(2):261-283

The utility of ostracod-based palaeoenvironmental reconstruction was evaluated using instrumental data for Lake Qarun, Egypt. The euryhaline ostracod Cyprideis torosa was the only species found in the lake’s recent sediment record. This species is known to tolerate salinity levels and water solute compositions that may prevent colonisation by other species. Oxygen and carbon isotope ratios of ostracod carbonate from lake sediments covary with changes in instrumental values for lake level and salinity for the period 1890–1974. δ¹³C-values correlate negatively with lake water salinity (r ² = 0.87) and δ¹⁸O-values correlate negatively with measured lake level changes (r ² = 0.41). Other ostracod proxy data provide qualitative information on lake level trends. Fossil assemblage data (juvenile/adult and valve/carapace ratios and valve preservation) provide information on wave energy. Ecophenotypic variation of C. torosa valves provided some useful palaeolimnological information. Sr/Ca and Mg/Ca ratios in ostracods were not found to reflect water composition, due to the uncoupling of these ratios with salinity in Lake Qarun. Overall, our results highlight the need to calibrate ostracod proxy data in modern systems prior to their use for palaeoenvironmental reconstruction.  相似文献   

The effects of organic removal treatment on the integrity of δ<Superscript>18</Superscript>O measurements from biogenic silica     

Jonathan J. Tyler  Melanie J. Leng  Hilary J. Sloane 《Journal of Paleolimnology》2007,37(4):491-497

Prior to oxygen isotope analysis of biogenic silica by fluorination techniques, sediments must be cleaned of all organic compounds. Despite the expanding volume of research utilising oxygen isotope ratios in biogenic silica in palaeoclimatology, very little is known about the effects of different standard preparation methods for the removal of organic matter on the isotope values. Here we compare a number of methods for the removal of organic matter in order to assess their effectiveness and influence on subsequent isotope measurements. Not all the methods described here effectively removed organic matter, the best treatments were H₂O₂ and ignition in air at 550°C. Ignition in air at 950°C, and heating in vacuum at 250 and 450°C results in marked alteration of isotope values, whereas use of hydrogen peroxide (H₂O₂), nitric acid (HNO₃) and plasma ashing have little or no effect, within the bounds of analytical error. Ignition in air at 550°C was the most effective technique, and induced no alteration of δ¹⁸O_silica, but practical constraints may limit the application of this method routinely. Our findings indicate that considerable caution is required when preparing sediment for isotope analysis of biogenic silica.  相似文献   

Assessment of δ13C and C/N ratios in bulk organic matter as palaeosalinity indicators in Holocene and Lateglacial isolation basin sediments,northwest Scotland     

Elizabeth A. V. Mackie  Jeremy M. Lloyd  Melanie J. Leng  Michael J. Bentley  Carol Arrowsmith 《第四纪科学杂志》2007,22(6):579-591

Carbon isotopes (δ¹³C) and C/N ratios from bulk organic matter have recently been used as alternative proxies for relative sea‐level (RSL) reconstruction where there are problems associated with conventional biological indictors. A previous study on a single isolation basin (Upper Loch nan Eala) in northwest Scotland has shown a clear relationship between δ¹³C, C/N ratios and palaeosalinity from Younger Dryas and Holocene aged sediments. In this paper we present results of δ¹³C and C/N ratio analyses from other isolation basins in northwest Scotland over the Holocene and the Lateglacial period in order to validate this technique. The results from the Holocene sequences support the earlier findings that this technique can be used to identify RSL change from isolation basins over the Holocene in this region. The relationship between δ¹³C, C/N ratios and RSL change is not apparent in sediments of Lateglacial age. Other environmental variables such as atmospheric CO₂ concentration, poor vegetation development and temperature influence δ¹³C values during this period. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Shell growth and oxygen isotopes in the topshell Osilinus turbinatus: resolving past inshore sea surface temperatures     

Marcello A. Mannino  Kenneth D. Thomas  Melanie J. Leng  Hilary J. Sloane 《Geo-Marine Letters》2008,28(5-6):309-325

Shells of the rocky shore intertidal gastropod Osilinus turbinatus (von Born), often abundant in archaeological deposits in the Mediterranean region, are a potential source of data on palaeotemperature, palaeoseasonality and archaeological seasonality. To evaluate this species as a climate archive, investigations of annual patterns of shell growth and of monthly variations in oxygen isotopes in shell carbonates were made on different populations in NW Sicily. Mark-recapture experiments at San Vito lo Capo and Mazzaforno show that O. turbinatus grows almost continuously throughout the year but at different rates in different seasons. Around 75% of the yearly shell growth occurs in the autumn and winter. On average, larger/older shells produce narrower annual growth increments than smaller/younger ones. Conspicuous growth lines in larger/older shells show that growth stops during the hottest part of the summer. Oxygen isotope analyses on monthly collected shells of O. turbinatus from three shores (Cala Grande, Monte Cofano and Mazzaforno) show that the isotope values record temperature variations through the year. In all the datasets, surface seawater temperatures (SSTs) calculated from δ¹⁸O_SHELL mostly underestimate measured SSTs, offsets being generally greater in summer. Minimum annual offsets range from 0.0°C to 0.7°C and maximum annual offsets from 3.1°C to 8.7°C. δ¹⁸O_SHELL values fail to record temperatures higher than 25°C. Careful selection of shells to be analysed can reduce offsets between δ¹⁸O_SHELL temperature estimates and measured SSTs for many parts of the year, except the hottest. Allowing for this, shells of O. turbinatus offer good potential as climate archives and for archaeological studies of seasonal patterns of human foraging for shellfish.  相似文献   

Evolution of aerosol vertical distribution during particulate pollution events in Shanghai          下载免费PDF全文

张云伟  张群  冷春鹏  张德芹  成天涛  陶俊  张仁健  贺千山 《Acta Meteorologica Sinica》2015,29(3):385-399

A set of micro pulse lidar(MPL)systems operating at 532 nm was used for ground-based observation of aerosols in Shanghai in 2011.Three typical particulate pollution events(e.g.,haze)were examined to determine the evolution of aerosol vertical distribution and the planetary boundary layer(PBL)during these pollution episodes.The aerosol vertical extinction coefficient(VEC)at any given measured altitude was prominently larger during haze periods than that before or after the associated event.Aerosols originating from various source regions exerted forcing to some extent on aerosol loading and vertical layering,leading to different aerosol vertical distribution structures.Aerosol VECs were always maximized near the surface owing to the potential influence of local pollutant emissions.Several peaks in aerosol VECs were found at altitudes above 1 km during the dust-and bioburning-influenced haze events.Aerosol VECs decreased with increasing altitude during the local-polluted haze event,with a single maximum in the surface atmosphere.PM2.5 increased slowly while PBL and visibility decreased gradually in the early stages of haze events;subsequently,PM2.5 accumulated and was exacerbated until serious pollution bursts occurred in the middle and later stages.The results reveal that aerosols from different sources impact aerosol vertical distributions in the atmosphere and that the relationship between PBL and pollutant loadings may play an important role in the formation of pollution.  相似文献   

日照市水资源利用现状及可持续利用研究     

冷爱国  孙爱华 《地下水》2010,32(6):147-149

分析了日照市的水资源现状以及在开发利用方面存在的问题,提出了解决水资源危机、确保城市可持续发展的策略和途径：实行地表水、地下水、城市雨水以及过境水的优化分配、联合调度;发展节水农业;配套高效、健全的保障体系;建设污水处理与中水回用工程;改善水库周边环境,提高水资源保护意识;采取有效的海水入侵防治措施等。  相似文献