Automated Analyte Separation by Ion Chromatography Using a Cobot Applied to Geological Reference Materials for Li Isotope Composition

The demand for large and reliable data sets on isotopic composition has increased in geochemistry and environmental sciences over recent years. We present an automated ion chromatographic separation method using a robotic pipetting arm, termed ‘ChemCobOne’, to reduce sample separation time. Its performance was tested for lithium isotope separation in geological reference materials using a single‐step separation with HCl (0.2 mol l^?1) and a 2 ml resin volume. This refined lithium purification method does not forfeit precision, accuracy or purity compared with manual sample processing. In addition, a δ⁷Li value for NASS‐6 of 30.99 ± 0.50‰ (2s) (95% CI = 0.14‰, n = 44) was determined and the first δ⁷Li values for the granite rock reference material GS‐N (?0.57 ± 0.25‰ (2s), 95% CI = 0.15‰, n = 15), and for the soil reference material NIST SRM 2709a (?0.37 ± 0.67‰ (2s), 95% CI = 0.15‰, n = 63) are proposed.     

Molybdenum Mass Fractions and Stable Isotope Compositions of Sedimentary Carbonate and Silicate Reference Materials

A double‐spike method in combination with MC‐ICP‐MS was applied to obtain molybdenum (Mo) mass fractions and stable isotope compositions in a suite of sedimentary silicate (marine, lake, stream, estuarine, organic‐rich sediment, shales, slate, chert) and carbonate reference materials (coral, dolomite, limestones, carbonatites), and a manganese nodule reference material, poorly characterised for stable Mo isotope compositions. The Mo contents vary between 0.076 and 364 μg g^?1, with low‐Mo mass fractions (< 0.29 μg g^?1) found almost exclusively in carbonates. Intermediate Mo contents (0.73–2.70 μg g^?1) are reported for silicate sediments, with the exception of chert JCh‐1 (0.24 μg g^?1), organic‐rich shale SGR‐1b (36.6 μg g^?1) and manganese nodule NOD‐A‐1 (364 μg g^?1). The Mo isotope compositions (reported as δ⁹⁸Mo relative to NIST SRM 3134) range from ?1.77 to 1.03‰, with the intermediate precision varying between ± 0.01 and ± 0.12‰ (2s) for most materials. Low‐temperature carbonates show δ⁹⁸Mo values ranging from 0.21 to 1.03‰ whereas δ⁹⁸Mo values of ?1.77 and ?0.17‰ were obtained for carbonatites CMP‐1 and COQ‐1, respectively. Silicate materials have δ⁹⁸Mo values varying from ?1.56 to 0.73‰. The range of δ⁹⁸Mo values in reference materials may thus reflect the increasingly important relevance of Mo isotope investigations in the fields of palaeoceanography, weathering, sedimentation and provenance, as well as the magmatic realm.     

Nitrogen Mass Fraction and Stable Isotope Ratios for Fourteen Geological Reference Materials: Evaluating the Applicability of Elemental Analyser Versus Sealed Tube Combustion Methods

Thirteen commercially available silicate reference materials (RM) and one in‐house reference material, eleven of which have no previously published values, were analysed for nitrogen mass fraction and isotopic ratios with an Elemental Analyser (EA), and a Sealed Tube Combustion line, coupled to a continuous flow isotope ratio mass spectrometer (IRMS). These materials ranged from < 10 μg g^?1 to 1% m/m nitrogen mass fractions and δ¹⁵N of ?0.5 to +19.8‰. Existing nitrogen RM BHVO‐2, MS#5 and SGR‐1b were used to assess the accuracy of the data from the sealed tube combustion line, which was found to be in good agreement with existing published values. In contrast, the EA‐IRMS failed to fully liberate nitrogen from all silicate rocks and minerals (achieving a mean of 44 ± 10% nitrogen yield) resulting in kinetic fractionation of isotope values by ?1.4‰ on average. Therefore, sealed tube combustion is better suited for analyses of silicate‐bound nitrogen. The EA worked reliably for organic samples, but care should be taken when using the EA for silicate nitrogen research. Moving forward, it is recommended that BHVO‐2, Biotite‐Fe, FK‐N and UB‐N be used as quality control materials as they appear to be most reproducible in terms of nitrogen mass fraction (relative error < 10%, 1s), and isotopic composition (< 0.6‰, 1s).     

中国油页岩富集与地质事件研究

油页岩是一种有机质富集的细粒沉积岩,高古湖泊生产力和稳定的还原环境是油页岩成矿的关键。越来越多的学者研究发现,在含油页岩沉积组合序列中,经常出现火山、热液、大洋缺氧、气候突变、海侵、重力流等地质事件。通过对全国50个盆地、95个含矿区油页岩成因和分布规律的总结和归纳,揭示出火山、热液、大洋缺氧、气候突变、海侵、重力流等事件不同程度地改变古湖泊水体条件,引发湖泊表层高生产力,促进藻类勃发和微生物繁盛,并形成稳定的湖泊分层环境,成为油页岩富集的有利因素。但若过量的火山灰、频繁火山爆发释放大量气体、高温高压的间歇性热液流体以及频繁的重力流作用将不利于油页岩富集。针对这些地质事件研究,目前还只停留在对单个事件的分析,未来需要从地球系统科学整体出发,促进沉积学、地球化学、微生物学等多学科交叉,揭示非常规油气资源沉积富集与重大地质环境突变的生态循环过程,进一步深入加强多种地质事件耦合作用对油页岩成矿影响,丰富非常规油气沉积学理论。     

Slowness–azimuth corrections of teleseismic events for IMS primary arrays in China

The seismic arrays at Hailar (HILR) and at Lanzhou (LZDM) in China are both primary stations of the International Monitoring System for verifying compliance with the Comprehensive Nuclear Test Ban Treaty. These two stations became operational in 2002 and have since then provided continuous data. In this study, the so-called slowness–azimuth station corrections (SASC) were derived and used to improve the location accuracy of the two arrays. The SASC are found by comparing the back-azimuth and slownesses obtained from array processing to the theoretical values calculated from the reported event locations and the corresponding seismic velocity model. Events reported by the National Earthquake International Center in the time period 2002 to 2006 were used as reference events, and the IASP91 was used as the theoretical velocity model. Small correction vectors with random orientation were found for HILR. Larger correction vectors with systematic vector biases were found for LZDM. The LZDM correction vectors seem to point to the same direction in a large part of the slowness space and may be attributed to local structure. After introducing the SASC for HILR, the standard deviations of back-azimuth and slowness residuals drop from 7.1° to 4.6° and from 1.0 to 0.6 s/°, respectively. For LZDM, these values drop from 22.3° to 10.2° and from 2.9 to 1.1 s/°, respectively. The variations of back-azimuth and slowness residuals were reduced by 32% and 30.2%, respectively, for HILR after SASC and the reductions were 21% and 40.2% for LZDM. The improvements were 77% in back-azimuth and 67% in slowness location for HILR and were 79% and 81% for LZDM after SASC. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

典型旱涝年环流的旬平均和旬距平特征

利用ＥＣＭＷＦ高度场资料，详细分析了１９８５年和１９９１年５月主要季风环流系统的旬平均和旬距平特征。结果表明，５月名旬，旱涝年的主要季风系统的位置和强度有明显差异。并指出夏季降水的异常，不仅与５月各旬北半球的南亚高压，极涡，西太平洋副高等系统的活动异常有关，而且与南半球的澳大利亚冷高，马斯克林高压的强弱有关，甚至与南半球中高纬环流的经向度大小也有联系。     

1960—2012年中国东部冬季风时期极端降温事件的时空特征

利用1960-2013年中国753个站逐日日平均气温资料,对中国东部冬季风时期极端降温事件进行了定义,并研究了近53 a中国东部冬季风时期极端降温事件的时空特征。结果发现,极端降温事件发生最频繁的地区位于东北南部、华北大部分地区和华中北部,华中南部则较少发生。过去的53个冬季风时期,中国东部极端降温事件普遍减少,且东北南部、华北南部和东部、华中北部以及华东北部的减少趋势最为明显,减小幅度可达0.4~0.8次/（10 a）。此外,东北、华北和华中的极端降温事件发生频次分别在1980、1973、1969年出现了由多到少的突变。极端降温事件的强度也存在空间差异,其平均强度从北到南呈现出强-弱-较强的特点。     

High-frequency climatic oscillations recorded in a Holocene coral reef at Leizhou Peninsula, South China Sea

A detailed study of the Goniopora reef profile at Dengloujiao, Xuwen County, Leizhou Peninsula, the northern coast of the South China Sea suggests that a series of high-frequency, large-amplitude and abrupt cold events occurred during the Holocene Hypsithermal, an unusual phenomenon termed “Leizhou Events” in this paper. This period (corresponding to ¹⁴C age of 6.2-6.7 kaBP or calendar age of 6.7-7.2 kaBP), when the climatic conditions were ideal for coral reefs to develop, can be divided into at least nine stages. Each stage (or called a “climate optimum”), lasting about 20 to 50 a, was terminated by an abrupt cold nap and (or) a sea-level lowering event in winter, leading to widespread emergence and death of the Goniopora corals, and growth discontinuities on the coral surface. Such a cyclic process resulted in the creation of a >4m thick Goniopora reef flat. During this period, the crust subsided periodically but the sea level was rising. The reef profile provides valuable archives for the study of decadal-scale mid-Holocene climatic oscillations in the tropical area of South China. Our results provide new evidence for high-frequency climate instability in the Holocene Hypsithermal, and challenge the traditional understanding of Holocene climate.     

Linear combinations of order statistics to estimate the position and scale parameters of the Generalized Pareto distribution

 Ad hoc techniques for estimating the position and the scale parameters of the Generalized Pareto distribution are introduced. The estimators proposed are simple linear combinations of the order statistics: they provide valuable estimates of the parameters of interest, both when the shape parameter is known and when it is unknown (this latter case being of great relevance in practical applications), and show a good performance as well when the sample size is small. The procedures are tested on simulated data, and comparisons with other techniques are shown.     

High flow events and sediment transport in small streams in the ‘tertiary basin’ area in piedmont (Northwest Italy)

Rainfall, peak discharges, and suspended sediment transport were surveyed for 280 events in three small (0.8 to 10 km²) catchments in a hilly area derived from Neogene marls, silts, and sands. Under similar hydrological input conditions, stream flow behaviour and sediment delivery differed considerably from one catchment to another, depending on topography, lithology, land use, and especially sediment availability. Analytical treatment of data showed a good fit between sediment yield and peak flow discharge. Less good, although still significant, was the correlation between sediment concentration and discharge values for different flow stages. Rainfall peak/basin lag time and rainfall/discharge showed poor or no correlation, mainly due to strong variations in rainfall distribution. Sediment concentration in the catchments varied enormously according to season, from zero up to 334 g 1^?1; sediment yield was 160-900 tonnes km^?2 yr^?1 in the two major catchments, and over 5200 tonnes km^?2 yr^?1 in the headwater catchment, stressing the importance of small tributaries not only in inducing floods in downstream channels, but also in sediment supply.