原子荧光法测定天然矿泉水及地下水中的痕量锗

将地下水及矿泉水水样蒸发浓缩后,于10％磷酸介质中,利用无色散原子荧光法的原理,选择了XDY—Ⅱ型原子荧光光度计仪器的最佳工作条件,试验了各种条件对锗测定结果的影响。测定结果表明,该方法的检出限为6.69μg/l,相对标准偏差为4.5％,锗的回收率为96.45％—105.0％。本法快速、灵敏、准确,可用于大批量天然矿泉水及地下水中痕量锗的测定。     

COUPLED PHYSICAL-ECOLOGICAL MODELLING IN THE CENTRAL PART OF JIAOZHOU BAY Ⅱ. COUPLED WITH AN ECOLOGICAL MODEL

ＩＮＴＲＯＤＵＣＴＩＯＮＭｕｃｈｅｆｆｏｒｔｈａｓｂｅｅｎｍａｄｅｔｏｗａｒｄｓｉｍｕｌａｔｉｏｎｏｆｔｈｅｅｃｏｓｙｓｔｅｍｅｖｏｌｕｔｉｏｎｉｎｃｏａｓｔａｌｚｏｎｅ.Ｔｈｅｆｉｒｓｔｍａｔｈｅｍａｔｉｃａｌｄｅｓｃｒｉｐｔｉｏｎｏｆｔｈｅｓｅａｓｏｎａｌｐｌａｎｋｔｏｎｄｙｎａｍｉｃｓ(Ｒｉｌｅｙｅｔａｌ.,1949)ｗａｓａｄｖａｎｃｅｄｂｙｔｈｅｅｃｏｌｏｇｉｃａｌｔｈｅｏｒｙｏｎｔｈｅｒｅｇｕｌａｔｉｏｎｏｆｐｏｐｕｌａｔｉｏｎｓｂｙｃｏｍｐｅｔｉｔｉｏｎａｎｄｐｒｅｄａｔｏｒｐｒｅｙｉｎｔ…     

Numerical Modelling of Geochemical Behaviour of Fluoride in the Shallow Groundwater Systems

The Xingtai piedmont plain in Hebei Province is a representative area in northern China where endemic fluorosis is serious and shallow high-F ground water is distributed. In this paper, the area is selected as a typical study area, and on the basis of large amounts of field work and the experiments, through groundwater geochemical modelling and by applying the theory and method of the coupled model of hydrodynamic transport and chemical reactions in a multicomponent system, the author performed numerical modelling of the geochemical behaviour of fluoride in a shallow groundwater system, quantitatively studied the hydrodynamic transport and chemical reaction of fluorine migration, transformation and concentration in a water-heterogeneous unsaturated soil system under the conditions of meteoric water infiltration and quantitatively determined the speciation of fluorine and the saturation state and dissolution/precipitation trend of various solid precipitates in shallow high-F groundwater, thus deepening t     

Stratospheric aerosol sulfuric acid: First direct in situ measurements using a novel balloon-based mass spectrometer apparatus

The first direct in situ measurements of the sulfuric acid contained in stratospheric aerosol particles were made using a novel balloon-based Ion Molecule Reaction Mass Spectrometer instrument (IMRMS) equipped with an aerosol vaporizer. The IMRMS method employed offers direct aerosol sulfuric acid measurements with high spatial resolution. The balloon flight took place on 23 October 1995 in middle latitudes (44°N) and reached a maximum altitude of 24 km. Measured molecular number densities of aerosol sulfuric acid decreased with increasing altitude from about 2.9 × 109 cm-3 at 15km altitude to about 2.4 × 108 cm-3 at 21 km. Corresponding mass mixing ratios are 2.5 and 0.6 ppbm, respectively. Calculated sulfuric acid mixing ratios from aerosol volumes inferred from aerosol size distribution measurements on the same balloon agree well with the IMRMS data using standard assumption aerosol composition.     

EAWM流型域——一种与东亚冬季风异常相联的海-气耦合流型域

提出海-气耦合流型域的概念,并探讨了与东亚冬季风异常有关的耦合流型域——EAWM 流型域。本文得出如下结果: 利用ECMWF分析资料10年的冬半年500 hPa高度场和同期COADS资料SST场,在SVD分析和聚类分析的基础上确定了三个海-气耦合流型域。第一个和第二个耦合流型域以ENSO事件冷暖位相与北太平洋/北美区的正负位相PNA型之间的关系为主要特征。第三个耦合流型域,即EAWM流型域则以强东亚冬季风环流型以及类似于La Ni?a事件冷暖分布却有明显区别的SSTA型为主要特征。数值试验结果表明,EAWM流型域的SSTA型,作为强迫,有利于东亚冬季风活动的加强并导致对应的大气型。数值试验同样证实,与强东亚冬季风活动相联系的EAWM流型域的大气型,作为强迫,可以导致该耦合流型域海温异常型的形成和维持。EAWM流型域的SSTA型和大气型间的这种双向相互作用导致正反馈过程,从而展示了该耦合流型域形成的主要特征,即以强东亚冬季风活动衔接的热带海-气相互作用以及热带内外大气相互作用。     

Cosmic ray produced isotopes in terrestrial systems

Continuing improvements in the sensitivity of measurement of cosmic ray produced isotopes in environmental samples have progressively broadened the scope of their applications to characterise and quantify a wide variety of processes in earth and planetary sciences. In this article, I will concentrate on the new developments in the field of nuclear geophysics, based on isotopic changes produced by cosmic rays in the terrestrial systems. This field, which is best described as cosmic ray geophysics, caught roots with the discovery of cosmogenic¹⁴C on the Earth by Willard Libby in 1948, and grew rapidly at first, but slowed down during the ’60s and ’70s. In the ’80s, there was arenaissance in cosmic ray produced isotope studies, thanks mainly to the developments of the accelerator mass spectrometry technique capable of measuring minute amounts of radioactivity in terrestrial samples. This technological advance has considerably enhanced the applications of cosmic ray produced isotopes and today we find them being used to address diverse problems in earth and planetary sciences I discuss the present scope of the field of cosmic ray geophysics with an emphasis ongeomorphology. I must stress here that this is the decade in which this field, which has been studied passionately by geographers, geomorphologists and geochemists for more than five decades, has at its service nuclear methods to introduce numeric time controls in the range of centuries to millions of years.     

Ocean Response to a Climate Change Heat-Flux Perturbation in an Ocean Model and Its Corresponding Coupled Model

State-of-the-art coupled general circulation models(CGCMs)are used to predict ocean heat uptake(OHU)and sealevel change under global warming.However,the projections of different models vary,resulting in high uncertainty.Much of the inter-model spread is driven by responses to surface heat perturbations.This study mainly focuses on the response of the ocean to a surface heat flux perturbation F,as prescribed by the Flux-Anomaly-Forced Model Intercomparison Project(FAFMIP).The results of ocean model were compared with those of a CGCM with the same ocean component.On the global scale,the changes in global mean temperature,ocean heat content(OHC),and steric sea level(SSL)simulated in the OGCM are generally consistent with CGCM simulations.Differences in changes in ocean temperature,OHC,and SSL between the two models primarily occur in the Arctic and Atlantic Oceans(AA)and the Southern Ocean(SO)basins.In addition to the differences in surface heat flux anomalies between the two models,differences in heat exchange between basins also play an important role in the inconsistencies in ocean climate changes in the AA and SO basins.These discrepancies are largely due to both the larger initial value and the greater weakening change of the Atlantic meridional overturning circulation(AMOC)in CGCM.The greater weakening of the AMOC in the CGCM is associated with the atmosphere–ocean feedback and the lack of a restoring salinity boundary condition.Furthermore,differences in surface salinity boundary conditions between the two models contribute to discrepancies in SSL changes.     

Butyltin compounds in a sediment core from the old Tilbury basin, London, UK

Sections from a sediment core taken from the River Thames were analysed for butyltin species using gas chromatography with species-specific isotope dilution mass spectrometry. Results demonstrated that in most samples tributyltin concentrations of 20–60 ng/g accounted for <10% of the total butyltin species present, which is in agreement with data from other sediment samples which were historically contaminated with tributyltin. Vertical distribution of the organotin residues with depth throughout the core, with data on organochlorine compounds and heavy metals allowed for the construction of a consistent hypothesis on historical deposition of contaminated sediments. From this it was possible to infer that the concentrations of tributyltin in sediments deposited during the early 1960s were in the order of 400–600 μg/g by using degradation rate constants derived by other workers. Such values fall well within the range quoted for harbour sediments in the literature.     

Organosulfates – A New Component of Humic-Like Substances in Atmospheric Aerosols?

Ion trap mass spectrometry (ITMS) was used to obtain further qualitative information about the chemical composition of humic-like substances (HULIS) in atmospheric particulate matter. Particles ≤10 μm (PM₁₀) were collected on quartz fiber filters for 24 h in the region of Basel (Switzerland) and extracted with water. HULIS were separated from inorganic salts by size exclusion chromatography (SEC) and detected by electrospray ionization in the negative ion mode (ESI(−)). Series of consecutive fragment ion spectra (MSⁿ) were recorded by ITMS. Full scan mass spectra of the extracts showed a mass distribution pattern characteristic for HULIS. Different molecular ions were selected from this pattern for further fragmentations. Among them the molecular ion m/z 299 was considered as representative and intensively studied. Many MS² and MS³ fragment spectra contained a fragment m/z 97 and a neutral loss of 80 u. Time-of-flight (TOF) MS and deuterium exchange experiments identified m/z 97 as hydrogen sulfate. MS² and MS³ fragment spectra supported the existence of sulfate covalently bound to HULIS. The fragmentation behavior of sulfated HULIS could be confirmed by model compounds.