Improvement of Oxygen Release from Calcium Peroxide‐polyvinyl Alcohol Beads by Adding Low‐cost Bamboo Biochar and Its Application in Bioremediation          下载免费PDF全文

Chih‐Hung Wu  Shih‐Hsien Chang  Chi‐Wen Lin 《洁净——土壤、空气、水》2015,43(2):287-295

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Paramagnetic lattice defects in quartz for applications to ESR dating     

《Quaternary Geochronology》2015

Quartz is one of the minerals useful for ESR dating with many applications. Although the study has quite a long history since 1980's, ESR dating of quartz is still in a developing stage. After the basis in physics for the ESR signals in quartz is described, the current status of ESR dating of quartz is summarized for applications to fault gouge, tephra and sediment. Both basic studies for mechanisms and practical applications with independent age controls are still necessary to establish the protocols.  相似文献   

大荔人遗址黄土-古土壤剖面岩石磁学性质研究   总被引：1，自引：0，他引：1       下载免费PDF全文

霍俊杰  Reidar Lovlie  李斌  苏朴 《地球物理学报》2010,53(6):1463-1474

自从大荔人化石被发现以来,其遗址剖面便成为研究热点.先前的研究主要集中在地层的对比划分与头盖骨年龄的推断方面,然而对于载磁矿物的鉴定及其古气候含义方面的研究却相对较少.鉴于此,本文运用热磁分析、饱和等温剩磁和剩磁矫顽力谱分析、磁滞回线分析、频率磁化率分析、热退磁分析等方法,对大荔人遗址剖面进行了系统的岩石磁学性质研究,鉴定出其主要载磁矿物为磁铁矿,赤铁矿,磁赤铁矿,磁畴状态主要是似单畴.磁铁矿,赤铁矿是样品中特征剩磁的携带者;主要起源于成土作用的超顺磁颗粒和新生成的亚铁磁性矿物,是古土壤样品磁化率增强的主要贡献者;古土壤中软磁性矿物的含量高于黄土.样品中磁赤铁矿的含量并不高.黄土-古土壤样品的频率磁化率曲线,古里雅冰芯氧同位素、细微粒浓度曲线,岐山五里铺剖面有机质含量曲线在古气候记录方面具有一致性,都展示出至少从MIS5以来,气候从冰期到间冰期的变化是渐变的,反之则表现了突变特征.上述岩石磁学研究丰富了大荔剖面的磁学领域研究内容,为相关课题的深入研究提供了依据.  相似文献   

Local variability of sedimentation rate in Lake Arendsee, Germany     

Burkhard W. Scharf  Bertram Boehrer  Conrad Kopsch 《Limnologica》2010,40(2):97-101

We measured the thickness and the dry weight of recently deposited sediment along several transects across Lake Arendsee in order to quantify the sedimentation rate and its local variability. As a time marker, we used an artificial marl layer that was deposited by a remediation program in the year 1995. A portion of the sediment deposited during the year was transported from the littoral and the top of the submerged hills to the foot of the slope, where we found the greatest deposition. Within the same lake, the deposited sediment layer varied by a factor of 4 between minimal and maximal values over the same time periods. Lake Arendsee is a holomictic and eutrophic lake with depletion of oxygen in summer time.  相似文献   

湖泊无机碳酸盐矿物氧同位素组成差值及其单矿物同位素组成的确定          下载免费PDF全文

曾承  吴鑫  钱晨阳 《盐湖研究》2010,18(1):21-28

湖积物中不同无机碳酸盐矿物常常混杂在一起,其氧同位素组成(δ18O)差异会影响碳酸盐δ18O环境信息提取的可靠性。不同矿物之间δ18O差值明显且幅度不一。20~25℃时生成的白云石比共生的方解石富集18O可能为0‰~9‰不等,亦或方解石比白云石可能更富集18O达0‰~12.3‰。常温状态,相同条件下形成的文石δ18O值较方解石高出0‰~1‰,或者方解石较文石δ18O值高出0‰~4.47‰。镁方解石中MgCO3的mol百分含量每增加1%,其δ18O值相对于纯方解石δ18O值增加0.06‰~0.17‰。在利用碳酸盐δ18O进行气候及环境研究时,不能根据某种差值进行校正,而应进行单矿物测试。由此,对不同无机碳酸盐矿物的分离及同位素测试、推算方法进行了归纳和述评。  相似文献   

Separation of Vanillin and Syringaldehyde from Oxygen Delignification Spent Liquor by Macroporous Resin Adsorption     

Zhaojiang Wang  Kefu Chen  Jun Li  Qianqian Wang  Jie Guo 《洁净——土壤、空气、水》2010,38(11):1074-1079

This paper reports on an approach for separating vanillin and syringaldehyde (VSA) from oxygen delignification spent liquor using non‐polar macroporous resin. The effects of temperature and pH on the adsorption isotherms were studied. The adsorption capacity and adsorption equilibrium constant were obtained using the Langmuir adsorption model at pH<4.5, where the ionization of the VSA to ionic forms was negligible. The standard enthalpy change was calculated using the van't Hoff equation and clearly showed that the adsorption is an exothermic process. The effect of pH on the adsorption isotherm is well‐described by a modified Langmuir model and shows that the adsorption equilibrium constant decreases significantly with the increasing pH. The VSA adsorbed on macroporous resin was eluted by ethyl ether. The separated VSA contained 37.51% vanillin, 31.88% syringaldehyde. The recoveries of VSA were 96.2 and 94.7%, respectively.  相似文献   

Using ocean quahog (<Emphasis Type="Italic">Arctica islandica</Emphasis>) shells to reconstruct palaeoenvironment in Öresund,Kattegat and Skagerrak,Sweden     

Elena Dunca  Harry Mutvei  Peter Göransson  Carl-Magnus Mörth  Bernd R. Schöne  Martin J. Whitehouse  Mikael Elfman  Susanne P. Baden 《International Journal of Earth Sciences》2009,98(1):3-17

Shells of Arctica islandica collected between 1884 and 2004 from Öresund, Kattegat and Skagerrak (Swedish West Coast) were used to monitor local climate variations and the influence of human activities on the local environment. For this purpose, we analysed the growth, structure and chemical composition of these shells and compared them with shells collected from Kiel Bay, Norway and Iceland. The growth rate of the studied shells registers an NAO periodicity of ca 8 years. However, the observed signal is weak because of other environmental interferences that are either of natural or anthropogenic origin. For example, the oxygen isotope ratios show temperature fluctuation, but also the influx of low salinity water. Higher contents of S, N, Cu, Zn, As, Cd and P in shell portions formed during the last century are related to human activities such as mining and industrial development. Our study indicates that in order to use Arctica shells as archives of climate change it is necessary to study the full range of environmental data that is recorded in the shells by using a multi element and isotope approach in combination with different analytical techniques including investigation of growth rates and shell structure.  相似文献   

Comparison of an Electrochemical and Luminescence‐Based Oxygen Measuring System for Use in the Biodegradability Testing According to Closed Bottle Test (OECD 301D)     

Judith Friedrich  Andreas Längin  Klaus Kümmerer 《洁净——土壤、空气、水》2013,41(3):251-257

The effects of persistent organic pollutants on the aquatic environment still can hardly be assessed. Therefore, ready biodegradability is a desired key characteristic of chemicals. Accordingly, biodegradation testing is of utmost importance and is a vital part within the risk assessment for organic chemicals. In the closed bottle test (CBT; OECD 301D) the degree of biological degradation of a chemical is assessed by monitoring the oxygen consumption so far with a Clark electrode as standard method. However, this method is time‐consuming, laborious and led to frequent fluctuations of the test results, which limited their validity. Due to these shortcomings, an optical system that enables contact‐free measuring of the oxygen concentration in a closed bottle, based on dynamic luminescence quenching, was examined. The test results were compared to those obtained with the “classical” electrochemical technique (Clark electrode). At first, a basic standard for the handling of the new instrument in the laboratory was developed. Then possible influencing factors, reliability, comparability, and reproducibility of the test results were investigated by running the CBTs in parallel with the electrode and optode method. The findings proved the new optode method to be unambiguously superior to the electrode technique. The frequency of fluctuations of the test results and time and effort necessary for the test run could considerably be reduced. The degradation kinetics of the test substances could be followed easily in the CBT by increasing the measuring points without much additional effort.  相似文献   

海水硝酸盐氮、氧同位素组成研究进展   总被引：2，自引：0，他引：2  

杨志  陈敏 《地球科学进展》2012,27(3):268-275

海洋中氮的生物地球化学循环影响着海洋生态系统的结构和功能,并和全球气候变化有着密切的联系,一直是海洋科学研究的重点和热点。海水硝酸盐的15N/14N和18O/16O比值可以反映海洋中氮循环的主要过程,因而成为研究海洋氮循环的一个重要手段。综述海水硝酸盐氮、氧同位素组成的测定方法,同化吸收作用、硝化作用、反硝化作用、生物固氮作用等氮循环过程所导致的氮、氧同位素分馏及其在海洋学研究中的应用。海洋生态系中硝酸盐氮、氧同位素的分布可以提供支持生物生产力的氮来源信息,以及氮在不同储库迁移转化的路径与机制。未来的研究需要发展适用于低含量硝酸盐的同位素测量方法,构筑海洋氮的收支平衡,掌握影响上层海洋硝酸盐氮、氧同位素变化的过程,获取全球海域有关硝酸盐氮、氧同位素组成的更多数据。  相似文献   

Rapid macrofaunal colonization of water-based drill cuttings on different sediments     

Trannum HC  Setvik S  Norling K  Nilsson HC 《Marine pollution bulletin》2011,62(10):2145-2156

A field experiment was conducted to investigate how water-based drill cuttings and sediment type influence colonization of soft bottom communities. Bottom frames with trays containing defaunated sediments were placed at the seabed for 6 months to study colonization of macrofauna. Two different sediments (coarse and fine) were used, and 6 or 24 mm layer of water-based drill cuttings were added on top of these sediments. Some of the sediments were controls with no additions. In the end of the experiment, the oxygen availability in sediment porewater and macrofaunal abundance were reduced in treatments with 24 mm drill cuttings compared to controls. Tube-building annelids were particularly sensitive to drill cuttings. However, these responses were only minor, and notably, the drill cuttings initiated a weaker faunal response than sediment type and site of the bottom frame. Sediments capped with water-based drill cuttings thus showed a rapid colonization of macrofaunal communities.  相似文献