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291.
As a gasoline additive, ethyl tert-butyl ether (ETBE) has great market potential and its utilization might cause groundwater contamination problem. However,
little research has been done on its sorption in soil. In this study, the sorption characteristics of ETBE to Chinese reference
soils were studied in batch experiments. The results showed that the ETBE sorption to six soils can be described by linear
sorption isotherm. The temperature influences the sorption process of ETBE to soils. The negative sorption enthalpy (ΔH < 0) indicated that the sorption process was exothermic. Furthermore, ΔH is in a range from −8 to −32 kJ/mol. This showed that van der Waals forces and other specific interactions happened simultaneously
in the sorption process. With the increasing ionic strength, content of ETBE sorption to all soils decreased, which is probably
also an indication of other sorption mechanisms besides ETBE partitioning into soil organic carbon. 相似文献
292.
针对贵州省黔西县大寨地区中三叠统关岭组底部绿豆岩,利用LA-ICPMS锆石U-Pb测年手段,明确贵州黔西县大寨地区早—中三叠世界线年龄。对贵州省黔西县大寨地区中三叠统关岭组底部绿豆岩1件U-Pb年龄样品、 8件地球化学样品的测试分析,结果表明,锆石U-Pb加权年龄为248.6 Ma±2.7 Ma,谐和年龄为248.7 Ma±1.1 Ma;绿豆岩属于高硅(wSiO2均值为62.40%)、铝(wAl2O_3均值为14.61%)、钾(wK2O均值为7.22%),低铁(wFe2O_3均值为0.94%,wFeO均值为0.51%)、钛(wTiO2均值为0.24%)的中酸性火山物质,具有稀土元素总量相对较低、相对富集轻稀土元素和轻重稀土元素分馏程度低的特征,负Eu异常显著,δEu=0.17~0.22。综合分析,该绿豆岩是由火山活动喷发的火山灰经风化、搬运、沉积改造而形成,为下三叠统嘉陵江组与中三叠统关岭组松子坎段界线岩性标志,同时为测区早—中三叠世界线年龄提供了准确的年代学证据。 相似文献
293.
Xiao-Cui Chen Rui-Zhong Hu Xian-Wu Bi Hui-Min Li Jiang-Bo Lan Cheng-Hai Zhao Jing-Jing Zhu 《Mineralium Deposita》2014,49(7):843-860
The Tengchong-Lianghe tin district in northwestern Yunnan, China, is an important tin mineralization area in the Sanjiang Tethyan Metallogenic Domain. There are three N–S trending granite belts in the Tengchong-Lianghe area, with emplacement ages ranging from Early Cretaceous to Late Cretaceous and Early Cenozoic. Tin mineralization is spatially associated with these granitic rocks. However, the petrogenetic link between the tin deposits and the host granites is not clear because of the lack of age data for the tin mineralization. We investigate the possibility of direct dating of cassiterite from three typical tin deposits in the Tengchong-Lianghe tin district, using laser ablation multicollector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS). In situ LA-MC-ICP-MS dating of seven cassiterite samples from the Lailishan (LLS-1 and LLS-2), Xiaolonghe (XLH, WDS, DSP, and HJS), and Tieyaoshan (TYS) tin deposits yielded well-defined 206Pb/207Pb–238U/207Pb isochron ages. To assess the accuracy of the in situ U/Pb dating of cassiterite, 40Ar/39Ar dating of coexisting muscovite (in samples LLS-1, DSP, and TYS) was also performed. The cassiterite in situ U/Pb ages (47.4?±?2.0, 71.9?±?2.3, and 119.3?±?1.7 Ma, respectively) are in excellent agreement with the coexisting muscovite 40Ar/39Ar ages (48.4?±?0.3, 71.9?±?1.4, and 122.4?±?0.7 Ma, respectively). The U/Pb ages of cassiterite combined with the 40Ar/39Ar ages of muscovite indicate that there are three tin mineralization events in this district: the Lailishan tin deposit at 47.4?±?2.0 to 52?±?2.7 Ma, the Xiaolonghe tin deposit at 71.6?±?2.4 to 3.9?±?2.0 Ma, and the Tieyaoshan tin deposit at 119.3?±?1.7 to 122.5?±?0.7 Ma. These ages are highly consistent with the zircon U/Pb ages of the host granites. It is su.ggested that the Cretaceous tin mineralization might have taken place in a subduction environment, while the Early Tertiary tin metallogenesis was in a postcollisional geodynamic setting. 相似文献
294.
通过对历史文献资料的收集整理,重建了清代江苏省冬季逐年冷暖等级序列,并利用Morlet复小波变换分析方法对序列进行了多时间尺度特征的综合分析。结果表明:(1)整个清代江苏省冬季气候变化大致可分为2个冷时段(1644—1730年、1821—1900年)和1个暖时段(1731—1820年);(2)重建的冷暖等级序列存在多尺度下的周期变化特征,其中有较明显的周期变化尺度是38~42 a、18~20 a、13~15 a和8 a,38~42 a和8 a特征时间尺度的周期变化相对具有全域性,18~20 a尺度的周期变化在1690—1790年之间比较明显,13~15 a尺度的周期变化在1720年之前和1830年之后比较明显;(3)重建序列的第1主周期为42 a,第2、3、4主周期依次是20 a、 8 a和3 a;在42 a尺度下,清代江苏省冬季气候可划分为6个偏冷时段和6个偏暖时段。 相似文献
295.
LA-ICP-MS分析技术是获取矿物/岩石内部的元素和同位素成分变化的重要手段。在利用该技术对地质样品进行线/面扫描时,仪器输出的初始数据量远远大于点分析,数据的处理和计算是一个关键问题。本文以磷质结核样品为例,阐述了利用Iolite软件进行元素线扫描数据计算的主要过程,包括背景信号的扣除、标准物质信号的拟合、线分析数据的导出等。借助软件自带的分段导出功能,对不同时间和空间分辨率下采集数据得到的结果进行了比较。研究表明Iolite能有效处理线分析数据,分析结果与前人用传统化学全岩法测定得到的元素含量范围相当。对比不同空间分辨率下(10μm、50μm、100μm)获取的数据发现:相对于选用的束斑直径(40μm),在分辨率过小(10μm)或过大(100μm)的条件下获得的数据存在数据波动大以及细节不足等缺陷;而当分辨率(50μm)与选用的束斑直径接近时,数据质量得到最大优化。本研究展示了Iolite软件在处理线扫描数据方面具有很好的应用前景,通过分辨率的选取可实现数据的优化。 相似文献
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Stable 18O and 13C isotope records of Viviparus diluvianus (Kunth, 1865) shells from Holsteinian (MIS 11) lakes of eastern Poland as palaeoenvironmental and palaeoclimatic proxies 下载免费PDF全文
Marcin Szymanek Krzysztof Bińka Jerzy Nitychoruk 《Boreas: An International Journal of Quaternary Research》2016,45(1):109-121
The oxygen and carbon stable isotope composition of Viviparus diluvianus shells was determined in the palaeolakes of the Holsteinian interglacial (MIS 11) in eastern Poland: the Ortel Królewski, Hrud, Ossówka, Roskosz and Szymanowo lakes. The occurrence of V. diluvianus covers the Taxus zone, the so‐called intra‐interglacial cooling period (Pinus‐Larix zone), the climatic optimum (Carpinus‐Abies zone) and the post‐optimal period with an undefined pollen zone. The isotope record of V. diluvianus shells allowed palaeoclimate and palaeoenvironmental reconstructions. δ18O and δ13C vary from −8.7‰ in the post‐optimal period to −4.8‰ in the optimal period, and from −10.6‰ at the beginning of the Taxus zone to −4.2‰ at the climatic optimum, respectively. A positive correlation of the isotope curves indicates closed‐water bodies, and only at Roskosz was some occasional overflow inferred. Higher oxygen isotopes correspond to an increase in temperature and/or enhanced evaporation, which is well marked in the Carpinus‐Abies zone, whereas samples enriched in 13C are correlated with periods demonstrating a lower water level and higher productivity in the lakes. Episodes of lake shallowing and dense aquatic vegetation occurred in the Pinus‐Larix zone and during the climatic optimum. The isotope ratios for the climatic optimum significantly exceed those of the other periods, thus pointing to warmer conditions. An estimation of relative changes of average summer temperatures using the δ18O/temperature gradient yielded variation of 1–2 °C within the lakes. Absolute temperature reconstructions indicate the effects of specific local conditions. Hence, V. diluvianus shells offer a reliable proxy in qualitative studies of interglacial lake records. 相似文献
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