准噶尔盆地腹部侏罗系原油勘探前景探讨

准噶尔盆地腹部地区长期以来以二叠系原油的勘探与研究为主。本文在总结本区现已发现侏罗系典型原油地球化学特征的基础上,通过混源油人工配比模拟实验揭示了侏罗系与二叠系原油在混合过程中的典型生物标志物变化特点,提出判识混源油组成的可能标志。据此标准,查清了研究区现有侏罗系原油和油砂的分布特点,再结合侏罗系烃源岩的分布情况,认为本区侏罗系原油可望具有良好的勘探前景,应重视对其勘探和研究。     

An application of artificial intelligence for rainfall-runoff modeling

This study proposes an application of two techniques of artificial intelligence (AI) for rainfall-runoff modeling: the artificial neural networks (ANN) and the evolutionary computation (EC). Two different ANN techniques, the feed forward back propagation (FFBP) and generalized regression neural network (GRNN) methods are compared with one EC method, Gene Expression Programming (GEP) which is a new evolutionary algorithm that evolves computer programs. The daily hydrometeorological data of three rainfall stations and one streamflow station for Juniata River Basin in Pennsylvania state of USA are taken into consideration in the model development. Statistical parameters such as average, standard deviation, coefficient of variation, skewness, minimum and maximum values, as well as criteria such as mean square error (MSE) and determination coefficient (R ²) are used to measure the performance of the models. The results indicate that the proposed genetic programming (GP) formulation performs quite well compared to results obtained by ANNs and is quite practical for use. It is concluded from the results that GEP can be proposed as an alternative to ANN models.     

Organic carbon source tracing and DIC fertilization effect in the Pearl River: Insights from lipid biomarker and geochemical analysis

The photosynthetic conversion of dissolved inorganic carbon (DIC) into organic carbon (OC) by using aquatic phototrophs in rivers may serve as a potential carbon sink, especially in the carbonate rock areas, thereby offering a clue for finding the missing carbon sink. However, primary-produced autochthonous OC is erroneously considered as terrestrial-derived allochthonous OC. Thus, carbonate weathering-related carbon sink is underestimated if only DIC concentrations sampled at river mouths are considered, and the transformation of DIC to autochthonous OC is neglected. Therefore, distinguishing sources of autochthonous and allochthonous OC is vital in the assessment of carbon sink. In this study, source-specific biomarkers, in association with chemical compositions and phytoplankton proxies in water samples collected from the Pearl River, were analyzed to determine OC sources. Results showed that biomarkers in the Pearl River were quite abundant, and the calculated average autochthonous OC was approximately 65% of the total OC, indicating intense in-river primary productivity. Moreover, phytoplankton biomass and DIC concentration were positively related, indicating the DIC fertilization effect on aquatic photosynthesis. High total suspended solid (TSS) on the water surface blocked the sunlight and then reduced phytoplankton production. However, in situ photosynthesis of phytoplankton could also produce autochthonous OC, even larger than the allochthonous source at sites with high DIC, and even with higher TSS concentrations. These findings comprehensively elucidated the formation of autochthonous OC based on the coupling action of rock weathering and photosynthetic activity in the riverine system, suggesting a potential direction for finding the missing carbon sink.     

红鳍笛鲷(Lutjnaus erythropterus)酪氨酸酶相关蛋白1基因克隆及表达分析

本文利用RACE技术克隆获得红鳍笛鲷(Lutjnaus erythropterus)酪氨酸酶相关蛋白1基因全长,并利用生物信息学方法对该基因的m RNA序列特征、氨基酸序列特征、分类及系统发生进行了分析。结果表明,在红鳍笛鲷中,酪氨酸酶相关蛋白1基因含有TYRP1a和TYRP1b两个拷贝,其中TYRP1a序列全长3178bp,开放阅读框(ORF)长1566bp,5?端235bp,3?端1377bp;TYRP1b基因c DNA全长1871bp,ORF区长1656bp,5?端89bp,3?端126bp。序列分析发现,TYRP1a和TYRP1b基因与其它物种的同源基因保守性较高,尤其是酪氨酸酶基因家族典型的酶活性位点序列在脊椎动物中具有高度保守性。进化分析发现,TYRP1a和TYRP1b基因的种间同源性高于两个基因间的同源性。荧光定量PCR数据分析表明,TYRP1a和TYRP1b基因都在眼睛部位具有最高表达,TYRP1b在黑色皮肤也有较高表达。结果可为进一步阐述TYRP1基因在红鳍笛鲷身体和眼睛部位的色素合成机制提供一定的理论基础。     

基于形态和16S rRNA基因的拟相手蟹分类研究

拟相手蟹属因其形态极其相似成为相手蟹科分类中最有疑问的一个属。通过对中国沿海近亲拟相手蟹Parasesarma affine、斑点拟相手蟹P. pictum、三栉拟相手蟹P. tripectinis、P. ungulatum及褶痕拟相手蟹P. plicatum 5种拟相手蟹的形态对比发现,可从它们的螯足形状(包括螯足掌节背面的梳状栉,可动指背面突起数目)及雄性第一腹肢形状对其进行区分。对其线粒体16S rRNA基因序列进行分子系统发育分析,结果表明5种拟相手蟹之间的遗传距离为1.9%～9.3%,达到了种间差异水平;构建的系统发育树显示近亲拟相手蟹与褶痕拟相手蟹汇聚成一支,随后与P. ungulatum聚在一起,斑点拟相手蟹与三栉拟相手蟹汇聚成独立支系。形态和分子证据均支持5种拟相手蟹分别为独立有效物种。     

海湾扇贝维甲酸受体(RXR)cDNA克隆与表达分析

维黄酸受体(RXR)是核受体超家族的重要成员,已有研究表明其在脊椎动物中广泛参与调控生长发育、新陈代谢等多种重要的生理过程。本研究采用RACE技术克隆获得海湾扇贝(Argopecten irradians)RXR(AiRXR)cDNA序列,采用荧光定量RT-PCR技术分析该基因在性腺发育不同时期的不同组织中的表达特点。结果表明,AiRXR的c DNA序列开放阅读框为1338bp,含有两个亚型:AiRXRα和AiRXRβ,两个亚型之间在T-box中相差4个氨基酸。该蛋白序列与人(Homo sapiens)和栉孔扇贝(Chlamys farreri)等的RXR相似性很高。AiRXR进化树分析显示,AiRXR与软体动物RXR聚为一支。AiRXR基因具有广泛的组织表达特点,在检测的组织中(外套膜、鳃、性腺、闭壳肌)均有表达,推测AiRXR以信号分子的形式参与多种组织细胞的生命过程;在海湾扇贝性腺发育过程中AiRXR基因在性腺发育的各时期均有表达且增殖期表达量最高,说明AiRXR基因可能参与调节性腺发育和分化的过程。     

羌塘盆地东部石炭系杂多群分子地球化学特征及地质意义

对羌塘盆地东部刻莫地区石炭系杂多群16个烃源岩样品的饱和烃和芳烃组分的GC-MS分析表明,其烃源岩正构烷烃主要是以C_(23)为主峰碳的单峰型,n C21-/n C22+值介于0.22~0.74之间,规则甾烷主要以C_(29)占优势,少数以C_(27)占优势,在C_(27)-C_(28)-C_(29)三角图中主要位于混合源区域,芳烃组分中检测出了与高等植物有关的海松烯和1-甲基菲。这些结果表明,杂多群烃源岩有机质生源以高等植物输入为主,低等水生生物有机质对成烃母质也有一定贡献。杂多群烃源岩Pr/Ph比值为0.83~1.43,一般大于1;1-甲基菲/9-甲基菲比值为0.77~9.95,1-甲基菲含量较高,同时还检测出源于高等植物的海松烯(1,7-二甲基菲);"三芴"系列化合物总体分布特征表现为OFSFF、SFOFF或者OFFSF,在ΣSF/(ΣF+ΣSF)-ΣOF/(ΣF+ΣOF)关系图上主要落于氧化-还原环境附近,可能为弱氧化-弱还原环境,也有部分样品位于沼泽相或煤的氧化环境中。杂多群烃源岩OEP值为1.01~1.16,C_(29)ααα20S/ααα(20S+20R)和C_(29)αββ/(ααα+αββ)比值分别为0.17~0.45和0.27~0.49,根据甲基菲和烷烃二苯并噻吩换算出的等效镜质体反射率平均值分别为0.70%和0.85%,反映出杂多群烃源岩具有成熟有机质的特征。     

内蒙古双尖子山银多金属矿床区域地球化学特征

内蒙古双尖子山银多金属矿床是中国乃至亚洲规模最大的银多金属矿床,本研究在回顾矿床发现史的基础上对双尖子山矿床区域地球化学数据进行再分析。采用19级累积频率法制作研究区39种元素或氧化物的地球化学图,结果发现在双尖子山矿区范围内出现明显高值的有MgO、CaO、Fe₂O₃、Pb、Zn、Ag、V、Cr、Ni等多达22种氧化物或元素,其中主量成分的明显富集特征应受控于研究区的岩性分布情况。采用变值七级异常法制作研究区29种微量元素的地球化学异常图,结果发现在双尖子山矿区及其附近存在W、Sn、Mo、Bi、Pb、Zn、Ag、As、Sb计9种热液成矿元素的异常区,而其他微量元素在双尖子山矿区的明显富集情况可能是由双尖子山矿区及其附近母岩岩性及其风化作用所致。基于地球化学基因技术制作了研究区金矿化基因和钨矿化基因的矿化相似度地球化学图,结果发现在双尖子山矿区及其附近存在金矿化相似度和钨矿化相似度的异常区,表明矿化相似度可以作为该区金属矿产勘查的一种有效指标,认为区域化探工作在该区金属矿产勘查中具有很好的参考价值。     

Amazon Fan biomarker evidence against the Pleistocene rainforest refuge hypothesis?

Ocean Drilling Program Leg 155 Site 942 on the Amazon Fan is an ideal location for monitoring palaeoclimatic changes within a significant proportion of the Amazon Basin. We present n‐alkane δ¹³C and taraxerol and laevoglucosan concentration records from this site covering the last 38 ka. The entire n‐alkane δ¹³C record is constrained between ?31‰ and ?34‰, which is well within the isotopic range occupied by C₃ vegetation. The concentration and relative abundance of taraxerol, a mangrove indicator, varies by over an order of magnitude, but seems to have had no effect on the n‐alkane δ¹³C record. The laevoglucosan concentrations are extremely low during the last glacial period, suggesting a relatively low occurrence of forest fires. Laevoglucosan concentrations are highest between 13.5 and 12.5 ka, suggesting an increased incidence of Amazon forest fires at the very end of the Younger Dryas. These records, combined with previously published pollen records from Site 932, reveal no evidence for massive incursions of grasslands into Amazonia during the last glacial period, despite evidence of reduced outflow of the Amazon River indicating more arid conditions. We therefore suggest that savannah encroachment, as proposed by the Pleistocene refuge hypothesis, can be refuted as an explanation for high species endemism within the Amazon Basin, and alternative explanations are required. Copyright © 2012 John Wiley & Sons, Ltd.