Solar Intranetwork Magnetic Elements: Evolution and Lifetime

Based on Hinode SOT/NFI observations with greatly improved spatial and temporal resolution and polarization sensitivity, the lifestory of the intranetwork (IN) magnetic elements are explored in a solar quiet region. A total of 2282 IN elements are followed from their appearance to disappearance and their fluxes measured. By tracing individual IN elements their lifetimes are obtained, which fall in the range from 1 to 20 min. The average lifetime is 2.9±2.0 min. The observed lifetime distribution is well represented by an exponential function. Therefore, the e-fold characteristic lifetime is determined by a least-square fitting to the observations, which is 2.1±0.3 min. The lifetime of IN elements is correlated closely with their flux. The evolution of IN elements is described according to the forms of their birth and disappearance. Based on the lifetime and flux obtained from the new observations, it is estimated that the IN elements have the capacity of heating the corona with a power of 2.1×10²⁸ erg s⁻¹ for the whole Sun.     

Sedimentary Environments of Cambrian–Ordovician Source Rocks and Ultra-deep Petroleum Accumulation in the Tarim Basin

The Tarim Basin is the only petroliferous basin enriched with marine oil and gas in China. It is presently also the deepest basin for petroleum exploration and development in the world. There are two main sets of marine Source Rocks (SRs) in the Tarim Basin, namely the high over-mature Cambrian–Lower Ordovician (∈–O1) and the moderately mature Middle–Upper Ordovician (O2–3). The characteristic biomarkers of SRs and oils indicate that the main origin of the marine petroleum is a mixed source of ∈–O1 and O2–3 SRs. With increasing burial, the hydrocarbon contribution of the ∈–O1 SRs gradually increases. Accompanied by the superposition of multi-stage hydrocarbon-generation of the SRs and various secondary alteration processes, the emergence and abnormal enrichment of terpenoids, thiophene and trimethylaryl isoprenoid in deep reservoirs indicate a complex genesis of various deep oils and gases. Through the analysis of the biofacies and sedimentary environments of the ∈–O1 and O2–3 SRs, it is shown that the lower Paleozoic high-quality SRs in the Tarim Basin were mainly deposited in a passive continental margin and the gentle slope of the platform, deep-water shelf and slope facies, which has exhibited a good response to the local tectonic-sedimentary environment. The slope of the paleo-uplift is the mutual area for the development of carbonate reservoirs and the deposition of marine SRs, which would be favorable for the accumulation of petroleum. Due to the characteristics of low ground temperature, the latest rapid and deep burial does not cause massive oil-cracking in the paleo-uplift and slope area. Therefore, it is speculated that the marine reservoirs in the slope of the Tabei Uplift are likely to be a favorable area for deep petroleum exploration, while the oil-cracking gas would be a potential reserve around the west margin of the Manjiaer Depression. Hydrocarbons were generated from various unit SRs, mainly migrating along the lateral unconformities or reservoirs and the vertical faults. They eventually brought up three major types of exploration fields: middle and lower Cambrian salt-related assemblages, dolomite inner reservoirs and Middle and Lower Ordovician oil-bearing karst, which would become the most favorable target of marine ultra-deep exploration in the Tarim Basin.     

地球物理数据网格化方法的选取

绘制地球物理数据等值线图时,需要根据客观环境特征和数据本身的特点,选择合适的网格化方法。通过实例,分别介绍了加权反距离插值法、克里格法、最小曲率法、最近邻点法、多项式回归法、径向基函数法、带线性插值的三角剖分法等常用网格化方法的选取方法、适用范围及参数设置等使用技巧。     

三峡蓄水后典型河段分形维数的变化分析

针对三峡工程蓄水后下游河道河床表面形态的变化,采用分形维数对河床表面形态进行量化,并分析河道冲淤调整特点,对河床表面分形维数(BSD)的变化特点及物理意义进行探讨。结果表明,BSD与河床各个剖面形态之间的关系是整体与部分的关系,BSD能全面地反映床面形态的复杂程度。三峡蓄水后,宜昌-虎牙滩和宜都河段BSD明显增大,关洲河段增大幅度较小,而芦家河河段BSD值略有减小,同时,各河段BSD的变化可在一定程度上表征三峡蓄水后下游河道河床综合阻力的调整结果。可通过对各河段演变趋势的分析,来预测其BSD的变化,进而为分析其阻力和水位的变化趋势提供依据。     

大渡河流域河谷深厚覆盖层特征与发育分布规律研究

随着近年来对西部各流域水电梯级开发的全面实施,越来越多的钻孔资料揭露我国西南地区各流域普遍存在河谷深切和深厚覆盖的特殊现象。河谷深切和深厚覆盖层的存在,不仅大大增加了西南地区各流域水电开发的难度,同时也诞生出一系列新的科学问题。本文以梯级水电站较密集、河床勘探资料相对较丰富的大渡河流域为主要研究对象,通过系统分析整理该流域河床钻探资料,对该流域河谷深厚覆盖层的分布特征、物质组成与结构特征、形成时间等进行了较为系统地分析总结,并对其形成机理提出了新的认识。研究结果表明,除局部地段受构造隆升(大岗山、下尔呷)或构造断陷(冶勒)的影响外,大渡河流域95％的河段其河谷覆盖层厚度大于30m,河谷深切和深厚覆盖具有流域性、区域性特点。河谷覆盖层是由一套不同时期、不同成因类型的沉积物相互迭置的结果,由表及里宏观上可分为3层: 表层为现代河流相堆积;  中间主要为以冰水、崩积、坡积、堰塞堆积与冲积混合为主的加积层,厚度相对较大;  底部主要为古河床的冲积、冰水漂卵砾石层。覆盖层的形成时代一般在1～3万年前,基本与地质历史上末次冰期及冰消期时间相对应。为了更好地解释河谷深切和深厚覆盖具有区域性的特点,本文提出了全球气候变化和海平面升降引起河谷深切和深厚覆盖的观点: 冰期海平面的大幅度下降会引起区域性基准面大幅下降,河流比降加大,由此引起强烈下切,形成深切河谷;  冰后期海平面大幅回升,区域性基准面将大幅抬升,河流纵比降减小,水流的携砂能力减弱,冰期河谷深切所形成的固体物质开始大量沉积,并由此形成深厚覆盖层。     

岱海与太湖沉积物焦碳和烟炱最近200年历史对比研究

黑碳是不完全燃烧产生的一种难熔的含碳物质的连续统一体,由焦碳(char)和烟炱(soot)组成.岱海与太湖沉积物焦碳和烟炱浓度对比显示,两个湖泊焦碳浓度和通量变化受局地火事件影响,无明显的规律; 而烟炱具有相似的变化历史,主要反映在1970年代后期急剧升高,与中国工业化历史一致.烟炱粒径细小,具区域传输特点,可以通过沉积物指示大气烟炱.结合当前大气气溶胶烟炱浓度,恢复了岱海与太湖地区最近200年来的大气烟炱浓度.其变化趋势与200年来北半球温度对比显示,大气烟炱中的高浓度对应于高温,低浓度对应低温.这种历史关系进一步证实大气烟炱在全球增温中具有极其重要的作用.     

地幔转换带中的水及其地球动力学意义

综述了近20年国际上地幔转换带中水的研究进展。前人研究表明,地球深部的水主要以OH-(hy-droxyl)形式存储在名义上无水矿物(NAMs)中。高温高压实验研究表明,地幔转换带中的主要矿物均具有较高的储水能力,且在转换带的温压条件下,其储水能力随着温度的升高而降低,其中瓦兹利石(β-Ol)和林伍德石(γ-Ol)的储水能力为2%～3%,超硅石榴子石(Mj)的储水能力为0.1%左右,据此估算地幔转换带的储水能力约为1.2%～1.91%,是地表水总量的3.9～6.2倍;而转换带除外的上地幔和下地幔主要矿物的含水量或储水能力均小于0.1%,因此与上、下地幔相比,地幔转换带可能是地幔的主要储水库。尽管地幔转换带具有较强的储水能力,但对地幔转换带的实际含水量还存在干、湿两方面的地质和地球物理证据和争议。地幔转换带中的水会对转换带中一系列的过程产生重要影响,当水含量增加时,橄榄石(Ol)向β-Ol、γ-Ol分解以及超硅石榴石的分解反应分别向低压、高压和低压方向迁移,从而由橄榄石向β-Ol和γ-Ol分解两个相变反应界定的转换带宽度也会增加;水还会使地幔深部的部分熔融温度降低,熔体的密度降低;同时,水的加入可以很好地解释地幔岩"pyrolite"模型在410km不连续面处产生的与地震波测量不相符突变,也可以解决全地幔对流模式所不能解释的地幔成分分层问题。因此,深入研究和探讨转换带中的水对地球深部动力学过程的影响,包括中国东部地区受太平洋板块深俯冲作用的影响,均具有重要的约束和研究意义。     

黄河黑山峡大柳树坝坝址岩体渗漏量及灌浆量数值模拟研究

大坝坝址岩体的渗漏研究对于大坝的安全运营至关重要。在进行渗漏治理的措施中,灌浆是常见的一种,但目前确定灌浆的各项参数,如配合比,孔距等,需通过灌浆试验花费大量的人财物力及时间才能确定。为快速查清每一种灌浆方案所灌浆量,本文针对模拟坝址水库渗漏灌浆效果的三维数值模拟开展了计算研究。在对大柳树坝坝址岩体地质情况及渗漏情况分析的基础上,将蓄水前的地下水运移规律模拟出,与实际通过钻孔平硐资料及分析得出的实际地下水运移规律做比较,验证对地下水运移规律的假设;然后将蓄水后的地下水运移规律模拟出,确定地下水的运移规律,了解地下水运移的方向,验证与根据实际情况初步判断的地下水运移方向是否吻合;最后通过数值模拟确定在一定灌浆浆液配合比的情况下所需灌浆量与实际的灌浆试验结果做比较。得出结果与实际灌浆试验结果吻合,证明通过数值模拟,建立浆液配合比与灌浆效果之间的关系,在类似情况快速地选取配合比是可行的。     

干湿交替条件下包气带土柱中氮素迁移转化规律实验

干湿交替的回灌方法常被用于解决地面回灌补给地下水的堵塞问题。研究干湿交替条件下地面回灌对地下水的影响对于指导再生水回灌地下水具有重要实际意义。通过室内土柱模拟实验,在入渗强度为10.5 mm/h的条件下,日均进水量3 888 mL;用干湿交替的地面回灌模式持续运行136 d,累计灌入氨氮含量为5 mg/L的模拟再生水23 894 L,研究包气带土柱对氨氮的去除效果及氮素在包气带中的迁移转化规律。研究表明,充分利用包气带的好氧、兼氧和厌氧环境,生物脱氮是地下水回灌过程中脱氮的主要途径。包气带对氨氮的去除机理主要为土壤对氨氮的吸附作用和微生物的降解作用。回灌过程中累积在土颗粒表面的氨氮在干期发生硝化作用,干湿交替会加强氮素在包气带的迁移转化,导致干期后的回灌初期大量硝态氮迁移到饱和带地下水中。     

Abiotic interactions of natural dissolved organic matter and carbonate aquifer rock

Abiotic interactions between natural dissolved organic matter (NDOM) and carbonate aquifer rock may be controlling factors of biogeochemical processes and contaminant fate in carbonate aquifer systems. The importance and effects of these interactions were examined using batch adsorption experiments of soil NDOM and representative carbonate sorbents from the Floridan Aquifer. Adsorption of NDOM carbon to aquifer rocks was well-described using a modified linear model and was mostly reversible. Significant adsorption was observed at higher NDOM concentrations, while the release of indigenous organic matter from the rocks occurred at lower concentrations. Longer interaction periods led to more adsorption, indicating that adsorption equilibrium was not achieved. For relatively pure carbonate rock samples, sorbent surface area was found to be the most important controlling factor of adsorption, whereas the presence of indigenous organic matter and subdominant mineral phases were more important, when they occurred. Preferential adsorption of a high over low molecular weight and humic over fulvic components of NDOM onto carbonate sorbents was detected using liquid size exclusion chromatography and excitation–emission fluorometry, respectively. The presence of NDOM inhibited mineral dissolution, though this inhibition was not proportional to NDOM concentration as surface area and mineralogy of carbonate sorbents played additional roles. Though the NDOM–carbonate rock adsorption mechanism could not be completely determined due to the heterogeneity and complexity of NDOM and sorbent surfaces, it is speculated that both rapid and weak outer-sphere bonding and stronger but slower hydrophobic interaction occur. These results have important implications for groundwater quality and hydrogeologic projects such as aquifer storage and recovery.