北京猿人洞堆积旋回与黄土和深海气候旋回对比

北京猿人洞13个堆积层可划分为7个堆积旋回。每个旋回早期的堆积层(砂、粉砂、粘土和钙扳层),含有暖温带气候特征的哺乳动物和孢粉组合;晚期的堆积层(洞穴角砾与巨砾层),含有温带较干冷气候特征的哺乳动物和孢粉组合。堆积层年代测定数据表明北京猿人洞7个堆积旋回形成于更新世中期,年代为128-730ka,与中国黄土层L2-S7,相当,可与深海氧同位素阶段6-19和气候旋回C-I对比。北京猿人在此洞断续生活了约35万年,即从距今约60万年的第5堆积旋回(δ18O第14阶段)至距今约25万年的第2堆积旋回(δ18O第8阶段)。     

Development of a real-time PCR method for Thalassiosira rotula rapid detection

Gene specific primers and DNA probe were designed based on the sequence of 18S rDNA cloned from the red tide alga Thalassiosira rotula. A real-time fluorescent quantitative PCR (RFQ-PCR) method was developed for quantitative detection of T.rotula. The RFQ-PCR assay data showed that the results obtained with the RFQ-PCR quite good agreement with those with the light microscope (LM) counting method, which suggested that the RFQ-PCR could be a useful method for red tide alga detection.     

Recharge source and hydrogeochemical evolution of shallow groundwater in a complex alluvial fan system,southwest of North China Plain

Many cities around the world are developed at alluvial fans. With economic and industrial development and increase in population, quality and quantity of groundwater are often damaged by over-exploitation in these areas. In order to realistically assess these groundwater resources and their sustainability, it is vital to understand the recharge sources and hydrogeochemical evolution of groundwater in alluvial fans. In March 2006, groundwater and surface water were sampled for major element analysis and stable isotope (oxygen-18 and deuterium) compositions in Xinxiang, which is located at a complex alluvial fan system composed of a mountainous area, Taihang Mt. alluvial fan and Yellow River alluvial fan. In the Taihang mountainous area, the groundwater was recharged by precipitation and was characterized by Ca–HCO₃ type water with depleted δ¹⁸O and δD (mean value of −8.8‰ δ¹⁸O). Along the flow path from the mountainous area to Taihang Mt. alluvial fan, the groundwater became geochemically complex (Ca–Na–Mg–HCO₃–Cl–SO₄ type), and heavier δ¹⁸O and δD were observed (around −8‰ δ¹⁸O). Before the surface water with mean δ¹⁸O of −8.7‰ recharged to groundwater, it underwent isotopic enrichment in Taihang Mt. alluvial fan. Chemical mixture and ion exchange are expected to be responsible for the chemical evolution of groundwater in Yellow River alluvial fan. Transferred water from the Yellow River is the main source of the groundwater in the Yellow River alluvial fan in the south of the study area, and stable isotopic compositions of the groundwater (mean value of −8.8‰ δ¹⁸O) were similar to those of transferred water (−8.9‰), increasing from the southern boundary of the study area to the distal end of the fan. The groundwater underwent chemical evolution from Ca–HCO₃, Na–HCO₃, to Na–SO₄. A conceptual model, integrating stiff diagrams, is used to describe the spatial variation of recharge sources, chemical evolution, and groundwater flow paths in the complex alluvial fan aquifer system.     

近400年来新疆策勒红柳沙包稳定氧同位素与气候变化

建立红柳沙包沉积纹层年代序列和提取气候环境信息是高分辨率古气候环境变化研究的重要手段。利用策勒达玛沟红柳沙包高度约450 cm沉积纹层红柳落叶的稳定氧同位素数据,结合策勒气象站1960~2011年观测数据,运用移动平均法对稳定氧同位素和气象数据进行平滑处理后,运用相关分析及逐步回归法,定量重建了策勒地区近400年来的4月平均气温和3月降水量序列。研究结果表明:红柳落叶δ^18O平均值为33.96‰,波动范围为27.18‰~44.07‰,波动幅度为16.89‰,δ^18O变化受多个气候要素的综合影响。δ^18O与4月平均气温呈显著负相关,与2月和12月平均气温呈显著正相关;δ^18O与10月、4月、5月、9月、7月以及全年的空气相对湿度呈显著正相关;δ^18O与3月、9月和8月的降水量呈显著正相关,与2月降水量呈显著负相关;δ^18O与2月日照时数呈显著正相关,与9月和10月的日照时数呈显著负相关。策勒地区近400年来气候变化可划分4个阶段:1635~1725年为暖干期,1726~1792年为冷湿期,1793~1897年为暖干期,1898~2009年为冷湿期。     

耳鲍(Haliotis asinina)核糖体小亚基(18S rRNA)编码基因的克隆与序列分析

采用分子生物学的方法,对南海不同海区的两个地理群体耳鲍(Haliotis asinina)18S rRNA基因全长进行了克隆和序列分析,并将耳鲍18S rRNA基因的序列与NCBI数据库中已收录鲍的18SrRNA基因进行了比较。结果发现,南海耳鲍核糖体18S rRNA基因与耳鲍H.asinina isolate H11核糖体18S rRNA基因序列的相同率高达98%;同一地理群体内耳鲍核糖体18S rRNA基因序列完全一致;不同地理群体间耳鲍核糖体18S rRNA基因在碱基组成上的相似率为99%,仅在某些位点处发生了碱基替换,即腺嘌呤(T)被鸟嘌呤(G)替换;同时,将这两个不同群体中耳鲍的18S rRNA基因与泰国耳鲍18S rRNA基因序列进行比较分析发现,它们之间也只是发生了碱基替换。     

Authigenic sericite record of a fossil geothermal system: the Offenburg trough,central Black Forest,Germany

A fossil geothermal area is hosted by the Carboniferous, Permian and Bunter sandstones of the Offenburg intramontane trough in the central Black Forest. The hydrothermal alteration is identified on the basis of newly formed sericites, which appear as pseudomorphs after feldspar and filling of pore spaces. According to K–Ar dating of sericite, serititization occurred about 145 Ma ago (Jurassic). On the basis of ¹⁸O analyses of sericite, sericite composition and vitrinite reflectance, the hydrothermal fluids had temperatures of 150–210 °C. Because their electrolyte content was low, these fluids are assumed to have derived from meteoric water. A second pulse of electrolyte-rich hydrothermal fluids resulted in quartz overgrowths. Fluid mobilization seems to be linked to the disintegration of Pangaea and to reactivated fault systems extending from the crystalline basement into the intramontane sediments.     

Simulation of river flow in Britain under climate change: Baseline performance and future seasonal changes

Climate change is likely to manifest in river flow changes across the globe, which could have wide-ranging consequences for society and the natural environment. A number of previous studies used the UK Climate Projections 2009 (UKCP09) to investigate the potential impacts on river flows in Britain, but these projections were recently updated by the release of UKCP18, thus there is a need to update flow studies. Here, the UKCP18 Regional (12 km) projections are applied using a national-scale grid-based hydrological model, to investigate potential future changes in seasonal mean river flows across Great Britain. Analysis of hydrological model performance using baseline climate model data (1980–2010) shows relatively good agreement with use of observation-based data, particularly after application of a monthly precipitation bias-correction. Analysis of seasonal mean flow changes for two future time-slices (2020–2050 and 2050–2080) suggests large decreases in summer flows across the country (median −45% by 2050–2080), but possible increases in winter flows (median 9% by 2050–2080), especially in the north and west. Information on the potential range of flow changes using the latest projections is necessary to develop appropriate adaptation strategies, and comparisons with previous projections can help update existing plans, although such comparisons are often not straightforward.     

Celestite formation, bacterial sulphate reduction and carbonate cementation of Eocene reefs and basinal sediments (Igualada, NE Spain)

Petrographic and geochemical studies of an Upper Eocene reef and associated basinal sediments from the mixed carbonate–siliciclastic fill of the south‐eastern Pyrenean foreland basin near Igualada (NE Spain) provide new insights into the evolution of subsurface hydrology during the restriction of a marine basin. The reef deposits are located on delta‐lobe sandstones and prodelta marls, which are overlain by hypersaline carbonates and Upper Eocene evaporites. Authigenic celestite (SrSO₄) is an important component in the observed diagenetic sequences. Celestite is a significant palaeohydrological indicator because its low solubility constrains transportation of Sr²⁺ and SO₄^2? in the same diagenetic fluid. Stable isotopic analyses of carbonates in the reef indicate that meteoric recharge was responsible for aragonite stabilization and calcite cementation. Sulphur and oxygen isotope geochemistry of the celestite demonstrates that it formed from residual sulphate after bacterial sulphate reduction, but also requires that there was a prior episode of sulphate recycling. Meteoric water reaching the reef and basinal areas was most probably charged with SO₄^2? from the dissolution of younger Upper Eocene marine evaporites. This sulphate, combined with organic matter present in the sediments, fuelled bacterial sulphate reduction in the meteoric palaeoaquifer. Strontium for celestite precipitation was partly derived in situ from dissolution of aragonite corals in the reef and basinal counterparts. However, ⁸⁷Sr/⁸⁶Sr data also suggest that Sr²⁺ was partly derived from dissolution of overlying evaporites. Mixing of these two fluids promoted celestite formation. The carbonate stable isotopic data suggest that the local meteoric water was enriched in ¹⁸O compared with that responsible for stabilization of other reefs along the basin margin. Furthermore, meteoric recharge at Igualada post‐dated evaporite deposition in the basin, whereas other parts of the same reef complex were stabilized before evaporite formation. This discrepancy resulted from the spatial distribution of continental siliciclastic units that acted as groundwater conduits.     

OIPC和RCWIP降水氢氧稳定同位素数据在新疆天山地区的适用性

降水中氢氧稳定同位素的空间分布是同位素水文学和同位素生态学研究的基础资料, 近年来高空间分辨率的氢氧稳定同位素分布数据产品获得了越来越多的重视。利用新疆天山地区实测降水同位素数据, 评估两套常用的全球降水同位素分布模拟数据（OIPC和RCWIP）的适用性。结果表明： 从时间尺度来看, 两套产品在夏半年（4 - 10月）的模拟效果明显优于冬半年（11月 - 次年3月）; 在各自然区中, 准噶尔盆地荒漠自然区的模拟效果相对较好, 而吐鲁番盆地-哈密（戈壁）荒漠自然区模拟效果相对较差。通过均方根误差、 线性判定系数、 平均偏置误差、 平均绝对误差等指标的比较, 在本研究区内RCWIP数据产品对降水同位素值的模拟效果比OIPC的效果好。结合乌鲁木齐多年降水氢氧稳定同位素数据, 发现降水同位素年际变化差异并未明显影响到代表性, 在缺乏长期监测的情况下这两套数据仍有重要的使用价值。