Biological and ecological factors related to trace element levels in harbour porpoises (Phocoena phocoena) from European waters

Selected trace elements (Cd, Cu, Hg, Se, Zn) were measured in the kidneys and the liver of 104 harbour porpoises (Phocoena phocoena) stranded along the coasts of France, Galicia (Spain), Ireland, Scotland (UK), and the Netherlands. Generally, relatively low concentrations of toxic elements were encountered in the tissues of European porpoises, except for two individuals, which displayed high hepatic Hg concentrations. Also, elevated Cd levels obtained in Scottish porpoises could be related to their feeding preferences and this result suggests an increase of the proportion of cephalopods in their diet with latitude. Moreover, significant geographical differences were seen in hepatic Zn concentrations; the elevated Zn concentrations displayed by porpoises from the Netherlands may relate their poor health status. Variation in metal concentrations within porpoises from the North Sea is likely to reflect a long-term segregation between animals from northern (Scotland) and southern areas (the Netherlands), making trace elements powerful ecological tracers.     

Neuroendocrine disruption in Mya arenaria clams during gametogenesis at sites under pollution stress

This study examined the neuroendocrine status of clams on intertidal mud flats in the St. Lawrence Estuary and Saguenay Fjord areas during late gametogenesis. The impact of pollution was determined by a test battery of early stress markers (metallothioneins, heme levels, glutathione S-transferase activity), tissue damage (lipid peroxidation and DNA damage) and morphologic characteristics (age, soft-tissue weight ratio and growth index). Neuroendocrinal status was examined by tracking serotonin and dopamine metabolism, monoamine adenylate cyclase activity in synaptosomes, monoamine oxidase and arachidonate cyclooxygenase activities in relation to gametogenetic activity: pyrimidine synthesis, (aspartate transcarbamoylase activity or ATC), vitellogenin-like proteins and gonado-somatic index. The results show that clam soft tissue weights were reduced at sites close to harbours and higher at sites near domestic wastewater outfalls. The age-to-length ratio of clams was generally higher at impacted sites, suggesting reduced growth. The biomarkers of stress or damage confirmed that oxidative stress, DNA damage, metallothioneins and glutathione S-transferase activity were significantly increased at varying degrees, at the polluted sites. Vitellogenin-like proteins and gametogenetic activity were significantly increased at sites influenced by domestic wastewaters. Furthermore, the clams were still in active gametogenesis and not ready for spawning, as indicated by the concordance of the serotonin/dopamine ratio with vitellogenin-like proteins and pyrimidine synthesis. However, gonadal cyclooxygenase activity was increased at polluted sites and significantly correlated with most of the stress biomarkers, suggesting that the clams were in a state of inflammation rather than at the spawning stage. Finally, a multivariate analysis revealed that the sites were readily discriminated with high efficiency (>71%) and that both neuroendocrine physiological markers and stress responses were identified as the major components, thus explaining the global physiological response of the clams. We conclude that the effects of pollution compromise the clams' health status and that the initiation of gametogenesis in environments contaminated by municipal wastewaters or harbours contributes to the toxic effects of pollution.     

页岩气储层压力测井评价模型研究——以涪陵地区龙马溪组页岩为例

欠压实/构造抬升背景下附加生烃增压是形成页岩气储层异常高压的主要成因机制,单一成因机制的压力评价方法无法准确解决这类储层压力评价难题.本研究以页岩孔隙组分测井评价为基础,分析页岩储层压力与不同类型孔隙的成因关系,依据压实平衡原理,评价欠压实/构造抬升作用形成的"背景孔隙压力",进而推导Ⅰ型高-过熟干酪根生烃附加增压测井...     

A new three-stage evolution model for millimeter to centimeter wavelength outbursts in BL Lacertae

The multi-frequency light curves of BL Lacertae during 1997.5 – 1999.5 have been modeled by four outbursts,each having a 3-stage evolution in the (S m,νm) plane with distinct rising–plateau–decaying phases.It is shown that the observed light curves can be well fitted for the eight frequencies from 350GHz to 4.8GHz.The main characteristics of the model-fitting are: (1) the outbursts are found to have very flat spectra with an optically thin spectral index α (defined as Sν∝ν-α) of about 0.15.This is consisten...     

辽河坳陷青龙台辉绿岩的Ar-Ar年代学和地球化学特征——对华北东部岩石圈减薄作用完成时间的限制

辽河坳陷青龙台辉绿岩全岩Ar-Ar同位素定年所获得的坪年龄为(35.5±0.7)Ma,与正反等时线年龄在误差范围内均相吻合,表明该辉绿岩侵位于新生代古近纪的沙河街期。地球化学分析结果显示,青龙台辉绿岩贫硅,富碱、钛,轻重稀土元素分异明显,略具Eu正异常,富集大离子亲石元素(LILE,如Sr、Ba等)和高场强元素(HFSE,如Nb、Ta等),显示与洋岛玄武岩(OIB)类似的地球化学特征。区域资料显示,华北克拉通东部晚白垩世-古近纪均以拉斑质玄武岩的喷发为主,为尖晶石二辉橄榄岩相高程度部分熔融的产物,新近纪以来则以碱性玄武岩的喷发为主,为石榴子石二辉橄榄岩相低程度部分熔融的产物。青龙台辉绿岩具较高的LaCN/YbCN、Ce/Y值和较明显的Sr、Ba、Eu异常,应是尖晶石-石榴子石过渡相的二辉橄榄岩经较低程度部分熔融的产物。因此,青龙台辉绿岩的形成时间可代表华北东部岩石圈由减薄至增厚的转折时间。     

贵州省煤炭资源有效保障能力分析

利用灰色聚类分析和层次分析等数学方法,建立了煤炭资源有效保障能力分析的数学模型,分析了贵州省煤炭资源有效保障能力。结果表明:贵州煤炭资源保障能力的基本态势是总量丰富,但有效供给能力不足。省内已发现资源的开采年限可达111a,但受限于资源特性和可采性,发现的资源/储量有效保障能力相对不足,净有效量确定的保障年限为45a,当前可供净有效量确定的保障年限仅为30a。     

双星演化与大样本恒星演化

主要介绍了大样本恒星演化所面临的困难，为解决困难所做的努力及对未来的展望。     

贵州矿山地质灾害类型及其基本特征

贵州是矿产资源大省,随着全省矿产开发利用规模、强度的不断扩大和提高,不可避免地带来了一系列的矿山环境地质问题的出现,其中矿山地质灾害数量多、分布广,其危害和威胁最为严重。根据实地调查结果,贵州省矿山地质灾害主要发育有采空地面塌(沉)陷、滑坡、崩塌(危岩)、泥石流和矿坑突水五类。其中,采空地面塌(沉)陷分布最广、造成的直接经济损失最严重,滑坡和崩塌频发、造成的人员伤亡最大。本文基于实际调查数据,从地质环境条件、矿种、矿山开采规模和开采方式等方面,分析论述了贵州省矿山地质灾害的主要类型、发育分布特征及其危害特点。     

三眼峪特大泥石流发展趋势分析

舟曲“8．8”特大山洪泥石流灾难之后,研究其发展趋势是做好舟曲灾后重建和防灾减灾工作的基础。通过现场调查和搜集历史数据,分析了泥石流再次爆发的可能性和发展趋势。认为三眼峪沟爆发泥石流的地形地貌和降雨条件依然存在,“8．8”特大泥石流的下泄量体积仅180×10^4m^3,仅为总物源的1／15,大量的松散物质仍然堆积在沟谷内,三眼峪仍然具有再次发生泥石流的可能性。三眼峪沟泥石流仍处于不断发展之中,频率和规模将呈现增大的趋势,灾后泥石流堆积扇上人员、住房和基础设施减少会使泥石流造成的灾害损失减小。