Towards a climate event stratigraphy for New Zealand over the past 30 000 years (NZ‐INTIMATE project)

It is widely recognised that the acquisition of high‐resolution palaeoclimate records from southern mid‐latitude sites is essential for establishing a coherent picture of inter‐hemispheric climate change and for better understanding of the role of Antarctic climate dynamics in the global climate system. New Zealand is considered to be a sensitive monitor of climate change because it is one of a few sizeable landmasses in the Southern Hemisphere westerly circulation zone, a critical transition zone between subtropical and Antarctic influences. New Zealand has mountainous axial ranges that amplify the climate signals and, consequently, the environmental gradients are highly sensitive to subtle changes in atmospheric and oceanic conditions. Since 1995, INTIMATE has, through a series of international workshops, sought ways to improve procedures for establishing the precise ages of climate events, and to correlate them with high precision, for the last 30 000 calendar years. The NZ‐INTIMATE project commenced in late 2003, and has involved virtually the entire New Zealand palaeoclimate community. Its aim is to develop an event stratigraphy for the New Zealand region over the past 30 000 years, and to reconcile these events against the established climatostratigraphy of the last glacial cycle which has largely been developed from Northern Hemisphere records (e.g. Last Glacial Maximum (LGM), Termination I, Younger Dryas). An initial outcome of NZ‐INTIMATE has been the identification of a series of well‐dated, high‐resolution onshore and offshore proxy records from a variety of latitudes and elevations on a common calendar timescale from 30 000 cal. yr BP to the present day. High‐resolution records for the last glacial coldest period (LGCP) (including the LGM sensu stricto) and last glacial–interglacial transition (LGIT) from Auckland maars, Kaipo and Otamangakau wetlands on eastern and central North Island, marine core MD97‐2121 east of southern North Island, speleothems on northwest South Island, Okarito wetland on southwestern South Island, are presented. Discontinuous (fragmentary) records comprising compilations of glacial sequences, fluvial sequences, loess accumulation, and aeolian quartz accumulation in an andesitic terrain are described. Comparisons with ice‐core records from Antarctica (EPICA Dome C) and Greenland (GISP2) are discussed. A major advantage immediately evident from these records apart from the speleothem record, is that they are linked precisely by one or more tephra layers. Based on these New Zealand terrestrial and marine records, a reasonably coherent, regionally applicable, sequence of climatically linked stratigraphic events over the past 30 000 cal. yr is emerging. Three major climate events are recognised: (1) LGCP beginning at ca. 28 000 cal. yr BP, ending at Termination I, ca. 18 000 cal. yr BP, and including a warmer and more variable phase between ca. 27 000 and 21 000 cal. yr BP, (2) LGIT between ca. 18 000 and 11 600 cal. yr BP, including a Lateglacial warm period from ca. 14 800 to 13 500 cal. yr BP and a Lateglacial climate reversal between ca. 13 500 and 11 600 cal. yr BP, and (3) Holocene interglacial conditions, with two phases of greatest warmth between ca. 11 600 and 10 800 cal. yr BP and from ca. 6 800 to 6 500 cal. yr BP. Some key boundaries coincide with volcanic tephras. Copyright © 2007 John Wiley & Sons, Ltd.     

无载气氢化物发生－石英缝管捕集原子吸收光谱法测定地质试样中的铋

文章介绍石英缝管原子捕集技术在氢化物－火焰原子吸收光谱法测定Ｂｉ中的应用。采用自制的无载气氢化物发生装置，对实验条件进行了最佳化。实验结果表明，原子捕集技术的应用使氢化物－火焰原子吸收法的灵敏度提高２．２倍；方法检出限（３σ）达２．５ｎｇ；２０ｎｇ／ｍｌＢｉ的标准溶液１０次测定的ＲＳＤ为２．９％。方法用于地质标样中微量Ｂｉ的测定，结果与推荐值符合。     

The effect of varied dam release mechanisms and storage volume on downstream river thermal regimes

Temperature plays an essential role in the ecology and biology of aquatic ecosystems. The use of dams to store and subsequently re-regulate river flows can have a negative impact on the natural thermal regime of rivers, causing thermal pollution of downstream river ecosystems. Autonomous thermal loggers were used to measure temperature changes downstream of a large dam on the Macquarie River, in Australia’s Murray-Darling Basin to quantify the effect of release mechanisms and dam storage volume on the downstream thermal regime. The magnitude of thermal pollution in the downstream river was affected by different release mechanisms, including bottom-level outlet releases, a thermal curtain (which draws water from above the hypolimnion), and spill-way release. Dam storage volume was linked to the magnitude of thermal pollution downstream; high storage volumes were related to severe thermal suppressions, with an approximate 10 °C difference occurring when water originated from high and low storage volumes. Downstream temperatures were 8 ̶ 10 °C higher when surface releases were used via a thermal curtain and the spillway to mitigate cold water pollution that frequently occurs in the river. Demonstrating the effectiveness of engineering and operational strategies used to mitigate cold water pollution highlight their potential contribution to fish conservation, threatened species recovery and environmental remediation of aquatic ecosystems.     

夏季黄海冷水团海域的丙烯酸分布与海洋环境因子和叶绿素a变化之间的关系

海水中主要含硫化合物β-二甲基巯基丙酸内盐(DMSP)降解可产生丙烯酸(AA)和活性气体二甲基硫(DMS)。2011年8月对黄海冷水团海域的AA及相关参量的分布特征进行了研究。结果表明,该海域表层海水中AA的浓度为0~0.208μmol/L,平均值为(0.081±0.075)μmol/L。AA的高值区出现在海域的东南部,可能是受到长江冲淡水的影响。AA的浓度总体上呈现出由南到北递增的趋势,与Chl-a较为一致,表明该海域的AA主要是由DMSP裂解产生的。表层海水中AA与温度表现出明显的负相关性。AA的垂直分布表现为:中层底层表层,这可能是产生AA的浮游植物与消耗AA的细菌共同作用的结果。海域中AA浓度与DMSP或DMS无明显的相关性。AA浓度远高于DMS,AA/DMS平均为106∶1,初步估算出DMSP降解产生的AA约为66.5%。AA/Chl-a平均为126.6 mmol/g,比DMSP/Chl-a高1个数量级,比DMS/Chl-a高2个数量级。     

Early Cambrian high pressure/low temperature metamorphism in the southeastern Tarim craton in response to circum-Gondwana cold subduction

The circum-Gondwana subduction initiated by the early Cambrian has been suggested to reflect the establishment of the modern plate tectonics. The metamorphic rocks with low thermobaric (T/P) ratios indicative of cold subduction in the present tectonic regime have not been well investigated. To better understand the circum-Gondwana subduction and to test its possible link with the emergence of the modern plate tectonics, this study focused on blueschist-facies metamorphic rocks in the Altyn Tagh of the southeastern Tarim craton. Mineral assemblage and chemistry, phase equilibrium modelling, and quartz-in-garnet Raman elastic geobarometry reveal that the zoisite blueschist and glaucophane (Gln)-bearing quartz schist in northern Altyn Tagh were metamorphosed to lawsonite to epidote blueschist-facies at 520–545 °C and 16–19 kbar. It reflects high-pressure (HP)/low temperature (LT) metamorphism with low T/P ratios of <300 °C/GPa and thermal gradients of <10 °C/km. These blueschist-facies metamorphic rocks underwent rapid decompression starting at P-T conditions of <495 °C and <9.6 kbar during exhumation. Ar-Ar geochronology records paragonite Ar-Ar plateau ages of 520–506 Ma for the zoisite blueschist samples and phengite Ar-Ar plateau ages of 522–516 Ma for the Gln-bearing quartz schist samples, suggesting that the peak HP/LT metamorphism occurred prior to ca. 522 Ma. Based on new results and available data from the major Gondwana blocks, cold subduction was suggested to profoundly operate along circum-Gondwana in the early Cambrian after the amalgamation of Gondwana. The extensive circum-Gondwana subduction represents the earliest global cold subduction in Earth’s history associated with the establishment of the modern plate tectonics, as directly recorded by the studied early Cambrian blueschist-facies metamorphic rocks and a dramatic drop in the mean T/P of metamorphism since the early Paleozoic.     

疏松砂岩稠油油藏出砂冷采机理及配套技术研究

稠油出砂冷采技术对地层原油含有溶解气的各类疏松砂岩稠油油藏具有较广泛的适应性，它通过大量砂子的产出和泡沫油的形成，获得较高的原油产量，河南油田于1996年在国内率先开展稠油出砂冷采技术调研及可行性研究，出砂冷采机理及配套工艺技术研究，并于1997年6月进入现场先导试验，矿场试验已展示出明显出砂冷采特征的G4906井，日产油量20t-30t，是常规开采和蒸汽吞吐的10倍和4倍以上，开采成本比蒸汽吞吐降低47%，出砂冷采工业化应用配套技术的形成和应用，将使国内及河南油田稠油资源利用程度进一步提高。     

Defining the Potential of Nanoscale Re‐Os Isotope Systematics Using Atom Probe Microscopy

Atom probe microscopy (APM) is a relatively new in situ tool for measuring isotope fractions from nanoscale volumes (< 0.01 μm³). We calculate the theoretical detectable difference of an isotope ratio measurement result from APM using counting statistics of a hypothetical data set to be ± 4δ or 0.4% (2s). However, challenges associated with APM measurements (e.g., peak ranging, hydride formation and isobaric interferences), result in larger uncertainties if not properly accounted for. We evaluate these factors for Re‐Os isotope ratio measurements by comparing APM and negative thermal ionisation mass spectrometry (N‐TIMS) measurement results of pure Os, pure Re, and two synthetic Re‐Os‐bearing alloys from Schwander et al. (2015, Meteoritics and Planetary Science, 50, 893) [the original metal alloy (HSE) and alloys produced by heating HSE within silicate liquid (SYN)]. From this, we propose a current best practice for APM Re‐Os isotope ratio measurements. Using this refined approach, mean APM and N‐TIMS ¹⁸⁷Os/¹⁸⁹Os measurement results agree within 0.05% and 2s (pure Os), 0.6–2% and 2s (SYN) and 5–10% (HSE). The good agreement of N‐TIMS and APM ¹⁸⁷Os/¹⁸⁹Os measurements confirms that APM can extract robust isotope ratios. Therefore, this approach permits nanoscale isotope measurements of Os‐bearing alloys using the Re‐Os geochronometer that could not be measured by conventional measurement principles.     

EPR investigation of the methyl radical,the hydrogen atom and carbon oxide radicals in Maxixe-type beryl

The EPR spectra of Maxixe-type beryl contain a large number of overlapping signals. The angular dependence of the 1:3:3:1 signal typical for the CH₃ radical shows that this radical is located at the center of the channel cavity with its symmetry axis parallel to the crystal c-axis and is rotating around this axis. Its EPR spectrum is axially symmetric with g _// = 2.00263, g _⊥ = 2.00249 and A_// = 2.288 mT, A_⊥ = 2.256 mT. These anisotropies have the opposite signs of those found for surface-adsorbed methyl radicals. Hydrogen atoms are located at position 2a at the center of the beryl cavity and the EPR parameters of the narrow doublet signal are A ₀ = 1,407 MHz and g = 2.00230. Another doublet signal, which is broader and has axial symmetry with g _// = 2.00265, g _⊥ = 2.00625 and A_// = 0.895 mT, A_⊥ = 0.885 mT, could come from a HCO₃ radical. One narrow and easily saturated signal with g _// = 2.00227 and g _⊥ = 2.00386 is interpreted to arise from a carbon monoxide radical in the beryl channel, oriented with its axis parallel to the crystal c-axis. Additional weak doublet lines, which have similar g values as the carbon monoxide radical, are created by nearby hydrogens. A powder spectrum with g _// = 2.0017 and g _⊥ = 2.0004 appears upon UV irradiation of the single crystal and is easily saturated. This spectrum is interpreted to arise from a carbon dioxide radical, which rotates around its symmetry axis.     

Vegetation and environmental conditions in the Doñana Natural Park coastal area (SW Iberia) at the beginning of the last glacial cycle

Detailed reconstructions of the vegetation of Iberia during the last glacial inception are rare due to the limited number of terrestrial sites recording this period. Active retreat of El Asperillo cliff, located on the Atlantic coast of southwestern Iberia, has exposed a fossil organic level dating back to one of the early stades of the last glacial cycle. Pollen and macrofossil analyses from this site show that the Doñana area was covered mainly by steppic vegetation; temperate trees survived the coldest periods, albeit in reduced numbers. Mediterranean taxa are extremely reduced, in contrast with other dry areas of southern Iberia over this time span. This vegetation suggests cold and arid climatic conditions, in accordance with paleoclimatic reconstructions based on several Atlantic marine cores.     

微机双道原子荧光光度计测控系统设计

该系统采用串口通信方式完成嵌入式单片机系统^[1]和计算机之间通信，通过测量待测溶液和标样的荧光强度来计算待测液中某痕量元素的含量，该系统具有图形化友好菜单操作、可视化的曲线分析和数据处理等特点。