硅酸盐氧同位素标样研制   总被引：1，自引：0，他引：1  

刘敬秀 《岩矿测试》1990,9(4):276-282

本文介绍了硅酸盐氧同位素标准物质(SH和H)的研制。均匀性检验证实该标准物质是均匀的。该标准物质采用直接比较测量法标定,即直接与国际标准V-SMOW和SLAP进行比较。 国际标准水样采用CO_2-H_2O平衡法制备CO_2;石英标样采用BrF_5法制备CO_2。将六个定值实验室提供的数据统一处理后,获得SH和H的δ~(18)Ox/v-s_(MOW)值分别为11.11±0.06(‰)和-1.75+0.08(‰)。该标准物质于89年12月被国家技术监督局批准为国家一级标准物质,山阳石英标样(SH)统一编号为GBW04409,浒坑石英标样(H)为GBW04410。  相似文献   

Seasonal variation in stable oxygen and carbon isotope values recovered from modern lacustrine freshwater mollusks: paleoclimatological implications for sub-weekly temperature records     

Christopher M. Wurster  William P. Patterson 《Journal of Paleolimnology》2001,26(2):205-218

A fingernail clam (Sphaerium simile, Sphaeriidae) from Science Lake, a small watershed located in Allegany State Park, New York, USA and a zebra mussel (Dreissena polymorpha, Dreissenidae) from Keuka Lake, New York, the third largest Finger Lake of central New York, were selected to evaluate the applicability of using ¹⁸O_(CaCO3) and ¹³O_(CaCO3) values for sub-weekly climate records. Seasonal variation in ¹⁸O_(CaCO3) values was compared with predicted equilibrium values to test the hypothesis that lacustrine molluscs produce shell aragonite according to environmental variables. For the purpose of comparison, aragonite temperature-fractionation equations determined by Grossman& Ku (1986) and Patterson et al. (1993) were used. Sphaerium simile appears to produce ¹⁸O_(CaCO3) values predicted by Patterson et al. (1993), while Dreissena polymorpha produces ¹⁸O_(CaCO3) values in agreement with Grossman & Ku (1986). We attribute the difference to family-specific temperature-fractionation relationships. Because both types of mollusc record climate variables with a high degree of integrity, they should each serve as excellent paleoclimate proxies.The fingernail clam collected from a small watershed exhibits higher variation about the seasonal pattern than did the zebra mussel collected from a large watershed. This is attributed to the increased sensitivity of the small watershed to storm perturbation. Analysis of fossil molluscs from such watersheds might be useful in discerning paleo-storminess.  相似文献   

地幔氧逸度的研究进展   总被引：13，自引：0，他引：13  

刘丛强  李和平  黄智龙  苏根利 《地学前缘》2001,8(3):73-82

通过对目前国际上诸多有关地幔氧逸度的研究结果的系统分析和总结 ,提出了地幔中自由氧对地幔物质的性质、状态及运动过程产生影响的基本作用方式 ;介绍了目前地幔氧逸度研究的主要研究手段 ,包括本征氧逸度的实验室测量、模拟氧逸度的实验室测量、地幔氧逸度计及理论计算等及其优缺点 ;定性探讨了地幔氧逸度的时空分布规律 ,获得了地幔随时间的推移变得愈来愈氧化 ,随深度的增加变得愈来愈还原 ,以及在横向上不同大地构造部位的地幔区域具有不同的氧逸度等诸多结论。结合目前人们对地幔物质组成、性质、状态、运动过程及地球的起源与演化历史等的认识 ,初步提出了地幔不同圈层氧逸度的约束机制。最后 ,针对目前地幔氧逸度的研究现状 ,为今后提出了一些参考性的研究方向。  相似文献   

青藏高原北缘哈拉湖近800年来 湖泊沉积及其环境意义^*   总被引：5，自引：5，他引：5  

曹洁  张家武  张成君  陈发虎 《第四纪研究》2007,27(1):100-107

文章以青藏高原北缘高山祁连山湖泊——哈拉湖作为研究对象,利用放射性核素²¹⁰ Pb和¹³⁷ Cs测年资料,通过对此高海拔湖泊沉积碳酸盐氧碳同位素、碳酸盐含量、总有机碳含量、磁化率等环境代用指标的分析,揭示了这一地区近800年来的气候环境变化过程。分析表明哈拉湖记录的气候环境变化经历了3个阶段:1206~1700A.D.环境较为寒冷、湿润,并有持续变湿的趋势;1700~1920A.D.环境由冷湿的状况趋向温暖干旱,1771年之后,环境保持相对稳定;1920~2002A.D.是自1206年以来最为温暖干旱的阶段。  相似文献   

椒江河口沉积物As、Hg黄铁矿矿化程度及其生物有效性          下载免费PDF全文

叶思源钟少军  丁喜桂袁红明 《地质论评》2007,53(4):499-505

本文利用取自浙江椒江河口3个未扰动柱状沉积物样,进行了孔隙水化学测试、固相沉积物的活性分量与黄铁矿分量的分级提取和测试,结果表明：Hg主要以黄铁矿态形式存在于沉积物中。As在有机碳较高的河口区潮上带和沉积速率较慢的潮下带主要以黄铁矿形态存在[DTMP（degree of trace metal pyritization,痕量元素黄铁矿矿化程度）〉50%）],而在中潮带As的黄铁矿矿化程度略低（DTMP均值为40.99%）,研究区DOP（Fe的黄铁矿矿化程度）值普遍较低（〈35%）,Mn-DTMP低于3.32%。从而揭示了浙江椒江河口沉积物在数厘米以下,毒性痕量元素Hg和As被高度黄铁矿矿化的规律性,并指出在遇有海事活动或风暴潮事件对海底沉积物进行扰动时,河口沉积物与充氧的海水反应,高度黄铁矿矿化的痕量元素会转变成活性态,从而导致近海生态系统的毒性事件。  相似文献   

High-resolution climate variability of southwest China during 57-70 ka reflected in a stalagmite δ18O record from Xinya Cave   总被引：1，自引：0，他引：1  

Li TingYong  Yuan DaoXian  Li HongChun  Yang Yan  Wang JianLi  Wang XinYa  Li JunYun  Qin JiaMing  Zhang MeiLiang  Lin YuShi 《中国科学D辑(英文版)》2007,50(8):1202-1208

A 26-cm-long stalagmite (XY2) from Xinya Cave in northeastern Chongqing of China has been ICP-MS ²³⁰Th/U dated, showing a depositional hiatus at 2.3 cm depth from the top. The growth of the 2.3–26 cm interval determined by four dates was between 57 ka and 70 ka, with a linear growth rate of 0.023 mm/a. We have analyzed 190 samples for δ ¹⁸O and δ ¹³C, mostly in the 2.3–26 cm part. The δ ¹⁸O and δ ¹³C values between 57 ka and 70 ka reveal decadal-to-centennial climatic variability during the glacial interval of Marine Isotope Stage 4 (MIS4), exhibiting much higher resolution than that of the published Hulu and Dongge records during this interval. Speleothem δ ¹⁸O in eastern China, including our study area can be used as a proxy of summer monsoon strength, with lighter values pointing to stronger summer monsoon and higher precipitation, and vice versa. Two decreases in the δ ¹⁸O signature of XY2 record around 59.5 and 64.5 Ka are argued to correspond to the Dansgaard-Oeschger (D-O) events 17 and 18 respectively. The Heinrich event 6 (H6) can be identified in the record as a heavy δ ¹⁸O peak around 60 ka, indicating significant weakening of the monsoon in Chongqing during the cold period. The XY2 δ ¹⁸O record shows very rapid change toward to the interstadial condition of the D-O event, but more gradual change toward to the cold stadial condition. This phenomenon found in the Greenland ice core records is rarely observed so clearly in previously published speleothem records. According to SPECMAP δ ¹⁸O record, the glacial maximum of MIS 4 was around 64.5 ka with the boundary of MIS 3/4 around 60 ka. Unlike the marine record, the speleothem record of XY2, China, exhibits much high frequency variations without an apparent glacial maximum during MIS 4. However, the timing of MIS 3/4 boundary seems to be around 60 ka when the H6 terminated, in agreement with the marine chronology. The growth period of sample XY2 during glacial times probably reflects a local karstic routing of water, rather than having climatic significance. Supported by the National Natural Science Foundation of China (Grant Nos. 40672165, 90511004, 40672202) and the Academician Special Project of Chongqing Science Committee (Grant No. 2003-7835)  相似文献   

对流层氮氧化物光化学转化特征研究   总被引：10，自引：0，他引：10       下载免费PDF全文

朱彬  孙照渤  安俊岭 《大气科学》2002,26(4):487-495

应用大气光化学模式研究了日间影响NOx光化学转化率的主要物理化学因子.探讨了在不同NMHC/NOx比值时,NOx光化学特征及其转化产物的变化规律.结果表明,影响NOx转化率的主要因子是阳光辐射强度和NMHC/NOx比值.但在NMHC/NOx比值很低时,光强的增加并不能显著提高NOx转化率.温度和初始臭氧浓度对NOx转化率的影响次之.相对湿度对NOx转化率的影响较小.在不同NMHC/NOx比值下,NOx转化特征和产物有很大区别.NMHC/NOx比值高时,产物中PAN＞HNO3.NMHC/NOx比值中(低)时,产物主要是HNO3,PAN等有机氮不到10%(1%).最后初步比较了模拟和观测的NOy组成.  相似文献   

胶南榴辉岩矿物氧同位素平衡及其Sm-Nd年代学制约   总被引：2，自引：4，他引：2  

郑永飞  王峥嵘  李曙光  李龙 《地球化学》2001,30(1):66-78

对苏鲁地体中的胶南榴辉岩进行了矿物氧同位素分析，并与同一手标本矿物的Sm-Nd内部等时线定年和Nd-Sr同位素分布进行了对比。研究表明，石榴子石与绿辉石之间的氧同位素平衡与否能够对矿物Sm-Nd同位素体系的平衡状况和内部等时线定年结果的有效性给予直接制约。合理的石榴子石＋绿辉石Sm-Nd内部等时线年龄产于两矿物之间达到并在峰变质条件下保持氧同位素平衡的样品中，而两矿物之间处于氧同位素不平衡的样品不能给出正确的Sm-Nd内部等时线年龄。同一矿物在手标本尺度出现显著的O-Nd-Sr同位素不均一性，据此对这些元素在石榴子石和绿辉石中的扩散速率顺序进行了估计，不仅得到了与实验扩散系数相吻合的结果，而且由此估计出在峰变质条件下达到矿物内部同位素均一化所需要的时间应大于10Ma。  相似文献   

A New Coastal Marine Ecosystem Model Study Coupled with Hydrodynamics and Tidal Flat Ecosystem Effect   总被引：3，自引：0，他引：3  

Akio Sohma  Yasuyuki Sekiguchi  Hiroshi Yamada  Tatsuaki Sato  Kisaburo Nakata 《Marine pollution bulletin》2001,43(7-12):187-208

A new coastal marine ecosystem model was developed, which was composed of pelagic and benthic ecosystems, and was applied to Mikawa Bay, Japan. This model deals with variations of biochemical and physical interactions among dissolved oxygen and C–N–P species (composition formed out of carbon, nitrogen and phosphorus elements) so that it resolves the flux dynamics of carbon, nitrogen, phosphorus and oxygen elements. The physical and biochemical mechanism figured in this model is constructed for the purpose of simulating the estuarine lower trophic ecosystem, in areas where the sea was too deep for light to reach the sea-bottom. As a result of coupling the benthic with pelagic system, the effect of process of sedimentation and nutrient diffusion back to the pelagic system could be indicated. In addition, by implementing the tidal flat ecosystem model's calculation result, the integrated model can include the effect of water purification in tidal flats where the light can reach the sea-bottom, and where sea-weed, sea grass and benthic algae exist. In this study, the model indicates that oxygen-depleted water exists at the sea-bottom especially in summer mainly caused by an increase of oxygen consumption in the benthic system and a decrease of the vertical mixing water process. Furthermore, by comparing the case – with the tidal flat ecosystem model and the case without it, the effect of water purification of tidal flat estuaries was indicated. From the viewpoint of a short time scale, the tidal flat has the potential to restrict red tide (rapid increase of phytoplankton), and from the viewpoint of a long time scale, it restricts the sedimentation of detritus. Restricting the sedimentation prevents oxygen-depleted water occurring in the coastal marine system of Mikawa Bay.  相似文献   

永城煤电集团滤波装置改造的技术经济分析     

艾永乐  康润生等 《中国煤田地质》2001,13(4):67-69

根据对永城煤电集团供电系统中存在的主要谐波情况，翔实分析了其所造成的附加损耗和经济损失。针对永城煤电集团用电负荷造成的谐波现状及现有的固定LC滤波装置的特点，经综合分析最后确定选用TCR型静止动态无功补偿装置与两矿现有的LC滤波装置并联，组成TCR＋FC结构。从技术、经济两方面看，具有重大意义。  相似文献