近年秋季南美沿岸海表温度周期性下降对ＥＮＳＯ事件的可能影响

文章分析了1950年以来赤道南美沿岸海表温度变化特点，发现1999年以来，Nino1＋2区海表温度的年变化振幅呈增大趋势，使得赤道东太平洋东北地区每年出现周期性降温，这主要是由秋季月平均SST最低值偏低造成，这种长时间持续偏低是1950年以来首次出现。进一步的分析表明，近年来南美沿岸海表温度在秋季的周期性下降可能对ENS0暖事件发生产生了影响，使得2002／2003ENS0暖事件成为20世纪50年代以粜由玲事件向瞎事件转换历时最长的一次．     

气候变化国家评估报告(Ⅰ):中国气候变化的历史和未来趋势

The climate change in China shows a considerable similarity to the global change, though there still exist some significant differences between them. In the context of the global warming, the annual mean surface air temperature in the country as a whole has significantly increased for the past 50 years and 100 years, with the range of temperature increase slightly greater than that in the globe. The change in precipitation trends for the last 50 and 100 years was not significant, but since 1956 it has assumed a weak increasing trend. The frequency and intensity of main extreme weather and climate events have also undergone a significant change. The researches show that the atmospheric CO2 concentration in China has continuously increased and the sum of positive radiative forcings produced by greenhouse gases is probably responsible for the country-wide climate warming for the past 100 years, especially for the past 50 years. The projections of climate change for the 21st century using global and regional climate models indicate that, in the future 20-100 years, the surface air temperature will continue to increase and the annual precipitation also has an increasing trend for most parts of the country.     

1-D and 2-D analyses of weak motion data in Fraser Delta from 1966 Duvall earthquake

The 1996 Duvall earthquake in Washington State triggered ground motion stations in the Fraser Delta, British Columbia, located on varying depths of Holocene and Pleistocene soils to a maximum depth of 800 m and one station on bedrock. Recorded ground motions were used to examine the applicability of 1-D and 2-D site response analyses for amplification studies in the Delta. 1-D response analysis gave a good indication of the period of peak response. Response spectra computed by 1-D analysis did not compare well with recorded spectra except at very deep sites. The use of 2-D analyses to include buried topography generally improved the predictions of site response spectra at the shallow sites. However, for the shallow earth sites, the recorded motions showed a strong spectral response at short periods in the range of 0.1–0.25 s. Neither 1-D nor 2-D analysis predicted this response.     

A new type of interaction between generalized Chaplygin gas and dark matter

In this paper, we investigate the model with a new type of interaction between generalized Chaplygin gas (GCG) and dark matter. It is shown that there exists a stable scaling attractor, which provides the possibility to alleviate the coincidence problem. The equation of state (EoS) of GCG approaches the attractor phase from either w _g >?1 or w _g w _g w _g w _g >?1), and next cross again the phantom divide (the transition from w _g >?1 to w _g Q can change its sign from Q<0 to Q>0 as the universe expands, which is different from the usual interaction. Moreover, we investigate the model from statefinder viewpoint. The statefinder diagnostic can not only discriminate the model with different coupling constant but also distinguish the model from other dark energy models.     

Study on Effects of Low Viscosity Fluid Pre-injection on Hydraulic Fracture Complexity in Tight Heterogeneous Glutenite Reservoirs

Tight heterogeneous glutenite reservoir is typically not easy to form complex hydraulic fracture (HF) due to its poor physical properties, poor matrix seepage capacity, and small limit discharge radius and undeveloped natural fracture system. To improve the HF complexity and the stimulated reservoir volume (SRV), a novel stimulation technology called CO₂ miscible fracturing has been introduced and its fracturing mechanism has been studied. The CO₂ miscible fracturing modifies the in situ stress field by injecting low viscosity fluid to increase the HF complexity and SRV. Therefore, a series of numerical simulations based on a hydro-mechanical-damage model were carried out to study the effects of low viscosity fluid pre-injection on pore pressure, stress field, and fracturing effect in tight heterogeneous glutenite reservoirs. The results indicate that the low viscosity fluid injection can effectively increase the pore pressure around the wellbore and reduce the effective stress of the glutenite. The FCI and SRV increase with the increase of the pre-injection amount of the low viscosity fluid. The HF complexity and SRV can be improved by pre-injecting low viscosity fluid to transform the in situ stress field. The field application of this technology in a well of Shengli Oilfield showed that low-viscosity fluid pre-injection can effectively increase the width of the fractured zone, improve the SRV, and optimize the fracturing effect.

     

鄂西宜昌地区页岩气勘探发现对MVT铅锌矿成矿的指示意义

油气成藏和有机质参与金属成矿的内在联系是近年来国内外地学界关注的热点问题.根据流体包裹体岩相学观察和激光拉曼光谱分析,在鄂西宜昌地区震旦系陡山沱组和下寒武统牛蹄塘组页岩储层及震旦系灯影组MVT（Mississippi Valley type）铅锌矿床中发现了高密度甲烷包裹体,并利用甲烷包裹体的甲烷拉曼散射峰v₁计算了甲烷包裹体的密度;同时采用Rb-Sr、Sm-Nd同位素定年确定了MVT铅锌矿成矿年代.鄂阳页1井陡山沱组页岩石英脉和何家坪MVT铅锌矿方解石样品中甲烷包裹体密度分别为0.237~0.278 g/cm3和0.213~0.271 g/cm3,属于高密度甲烷包裹体.何家坪铅锌矿共生矿物闪锌矿和方铅矿的Rb-Sr等时线年龄为189.1±1.8 Ma,方解石的Sm-Nd等时线年龄为189.9±2.0 Ma,指示铅锌矿形成于燕山早期的构造挤压运动;共生矿物的初始87Sr/86Sr值（0.711 92）和方解石的初始87Sr/86Sr值（0.712 03~0.712 27）指示何家坪铅锌矿成矿流体的Sr同位素主要来源于页岩层.何家坪铅锌矿中捕获的以流体包裹体形式存在的高密度甲烷流体最有可能来源于陡山沱组页岩和/或牛蹄塘组页岩内高密度超压甲烷流体.页岩气层和MVT铅锌矿中高密度甲烷包裹体的发现及MVT铅锌矿成矿时间的确定为探讨有机质参与MVT铅锌矿成矿提供了新证据.      

渝东北奥陶-志留纪之交沉积地球化学及其环境演化--以城口地区燕麦剖面临湘组-龙马溪组为例

通过沉积及元素地球化学分析,重庆城口地区燕麦剖面临湘组自底部小瘤状灰岩向上沉积岩性依次为褐黄色泥灰岩、暗灰绿色泥岩,逐渐过渡为五峰组-龙马溪组深灰色硅质泥岩。水体深度呈现出由深变浅再变深的特征,向上总体水体还原性增强、氧化性减弱,在临湘组中上部存在微弱的氧化性增强的特征,指示区域构造短暂抬升,水体变浅,为宜昌上升运动的早期响应。古生产力指标显示氧化条件较好的观音桥段以及临湘组下部（层5）具有更高的生物生产率,与冰期气候变冷海平面下降导致上升洋流盛行以及水体氧化还原条件改善有关。燕麦剖面临湘组-五峰组-龙马溪组倾向于活动型大陆岛弧环境沉积,自下向上陆源组分含量逐渐降低,火山碎屑组分含量逐渐升高。剖面上部五峰组和龙马溪组底部硅质泥岩热水沉积地球化学特征较为明显,可能受到深部热液活动的影响。     

Late Ordovician high-Mg adakitic andesite in the western South China block: evidence of oceanic subduction

The Early Palaeozoic was an important period in the geologic evolution of the South China block (SCB), marking the intracontinental orogen in the Wuyi-Yunkai region. One salient feature of the western SCB is the absence of Early Palaeozoic oceanic subduction-related magmatism. Here, we report the first known occurrence of Late Ordovician andesites from the Shimian area, western SCB. Zircon SHRIMP U–Pb dating reveals that the andesites formed at ca. 451 Ma. They have geochemical features of high-Mg adakitic andesite (HMAA) and are characterized by low K₂O (1.09–2.24 wt.%) and Th (2.50–5.65 ppm) and high MgO (4.02–6.91 wt.%) and Mg# (56–71). Furthermore, their zircon grains display positive ε_Hf(t) (+11.4 to +19.6) and low δ¹⁸O (4.72–6.20‰) values. The andesites are interpreted to have been derived from partial melting of a peridotitic mantle wedge in an oceanic subduction setting and subsequent fractional crystallization. Integrating previous studies of the Qinling-Dabie orogenic belt with the data presented in this contribution, we suggest that the SCB was probably involved in the Early Palaeozoic Andean-type orogeny along the Gondwanan proto-Tethyan margin.     

Comparison of Fenton,ultraviolet–Fenton and ultrasonic–Fenton processes on organics and colour removal from pre-treated natural gas produced water

Produced water (PW) from natural gas field, characterized with high organic contents, has brought high environmental concerns world widely. Fenton and enhanced Fenton technologies were considered as the potential methods to degrade the organic contaminates in the PW, but with very limited data or reference. Here, we examined the optimum conditions of Fenton on organics and colour removal from natural gas PW after coagulation pre-treatment. Simultaneously, the optimal Fenton process integrated with ultraviolet (UV) and ultrasonic (US) irradiation were applied to enhance pollutants removal efficiencies. The optimal Fenton conditions were found at 60 min with molar ratios of 6:1 and 25:1 for H₂O₂/COD and H₂O₂/Fe²⁺, respectively and the initial pH of 3. Among these the three treatment processes, chemical oxygen demand (COD), total organic carbon, 5-day biological oxygen demand (BOD₅), and colour removal efficiencies were highest during UV–Fenton (82, 73, 68, and 95%,) followed by US–Fenton (79, 70, 66, and 95%) and Fenton treatment (70, 58, 51, and 92%), respectively. High biodegradability (BOD₅/COD) was also observed after UV–Fenton process (0.76) than the others (both 0.73). The current study showed a satisfactory carbon and colour removal efficiencies from PW using different Fenton processes; however, there still is a need for final polishing such as biological treatment or low cost constructed wetland before discharge. This study can be a good reference for engineering application PW treatment.     

First observation of domoic acid and its isomers in shellfish samples from Shandong Province,China

Journal of Oceanology and Limnology - A total of 133 shellfish samples were collected in seven cities of Shandong Province, China, from May to October, 2019. The domoic acid (DA) concentrations...