检索结果-南通市图书馆

在线全文

学校读者我要写书评

暂无评论

极地峡湾有机碳来源和埋藏研究进展

海洋地质与第四纪地质 2022年第4期42卷 73-83页

作者：万霞张海龙肖晓彤中国海洋大学深海圈层与地球系统前沿科学中心和海洋化学理论与工程技术教育部重点实验室青岛266100 青岛海洋科学与技术试点国家实验室海洋生态与环境科学功能实验室青岛266237

峡湾是开阔海洋与陆地生态系统重要的连接区域,在全球气候变化的背景下,峡湾的生物地球化学过程正发生剧烈的变化。峡湾的特殊地形以及生物地球化学特性使其成为有机碳埋藏和储存的重要区域。研究表明,全球峡湾的平均有机碳累积速率高达... 详细信息

峡湾是开阔海洋与陆地生态系统重要的连接区域,在全球气候变化的背景下,峡湾的生物地球化学过程正发生剧烈的变化。峡湾的特殊地形以及生物地球化学特性使其成为有机碳埋藏和储存的重要区域。研究表明,全球峡湾的平均有机碳累积速率高达54 gc·m^(−2)·a^(−1),有机碳埋藏量为18×10^(12) gc·a^(−1),约占全球海洋有机碳埋藏量的11%,有巨大的储碳潜力。极地峡湾由于存在冰川作用,其沉积有机碳的输入、迁移转化和埋藏呈现与温带峡湾不同的特征。极地峡湾湾内以及各峡湾之间的沉积有机碳来源、组成和累积、埋藏速率均存在空间差异,湾内表现为由峡湾前端向湾口方向的梯度变化;各峡湾之间表现为有冰川的峡湾比无冰川的峡湾有更高的碳累积速率;沉积有机碳组成差异受到淡水和海水输入的影响。厘清峡湾沉积有机碳的来源对认识峡湾有机碳埋藏至关重要,通过测定总有机碳及单体化合物放射性碳同位素可实现对不同来源有机碳的定量估算。全球变暖使冰川快速消融,导致极地峡湾表现出不同的有机碳累积或埋藏特征,而在全球碳循环中,极地峡湾捕获和埋藏有机碳的能力是否能适应全球气候变化变得愈发重要。

关键词：峡湾沉积物 14c 有机碳埋藏气候变化

Interactive Effects of Lead and Bensulfuron-Methyl on Decomposition of ^(14)c-Glucose in Paddy Soils

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2009年第5期19卷 577-587页

作者： HOU Xian-Wen WU Jian-Jun XU Jian-Ming TANG cai-Xian Institute of Soil and Water Resources and Environmental Science Zhejiang Provincial Key Laboratory of SubtropicalSoil and Plant Nutrition Zhejiang University Hangzhou 310029 （China） Institute of Environmental and Plant Protection Chinese Academy of Tropical Agricultural Sciences Danzhou 571737（China） Department of Agricultural Sciences La Trobe University Victoria 3086 （Australia）

Little information is available on the interactive effects of inorganic and organic pollutants on carbon utilization by soil microorganisms.This study examined the effects of two common soil pollutants,lead(Pb) and bensulfuron-methyl herbicide(BSM),on decomposition of an adscititious carbon source(14c-glucose).Two contrasting paddy soils,a silty clay soil and a clay loam soil,were incubated with different concentrations and combinations of pollutants for 60 days.Orthogonal rotatable central composite design was adopted to design the combinations of the pollutant concentrations so that rate response curves could be derived.Rapid decomposition of 14c-glucose occurred in the first three days for both soils where no Pb or BSM was added(control).Overall,63%-64% of the added 14c-glucose was decomposed in the control over the 60-day incubation.The addition of Pb or BSM significantly decreased the decomposition of 14c-glucose during the first week but increased the decomposition thereafter;as a result,the percentages of 14c-glucose decomposed(57%-77%) over the 60-day period were similar to or higher than those of the control.Application of the pollutants in combination did not further inhibit decomposition compared with the control.Overall,decomposition rates were lower in the silty clay soil than in the clay loam soil,which was related to the soil texture,cation exchange capacity,and pH.The relationship between the decomposition rates and the pollutants could be well characterized by the quadratic regression orthogonal rotation model.The initial antagonistic effects of the pollutants followed by the synergistic effects on microbial activity might result from changes of the concentrations of the pollutants.

关键词：互动效应葡萄糖水稻土 14c 分解铅

Hydrological changes and settlement migrations in the Keriya River delta in central Tarim Basin ca. 2.7–1.6 ka BP: Inferred from ^(14)c and OSL chronology

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2011年第12期54卷 1971-1980页

作者： ZHANG Feng WANG Taoi Hamid . YIMIT SHI QingDong RUAN QiuRong SUN ZhiQiong LI Fang Key Laboratory of Desert and Desertification Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China Key Laboratory of Oasis Ecology （Xinjiang University） Ministry of Education Urumqi 830044 China School of Geographic Sciences and Tourism Xinjiang Normal University Urumqi 830054 China Xinjiang Institute of cultural Relics andArchaeology Urumqi 830000 China

Over one hundred artifacts, including shards, chopped wood, bronze and iron ware debris as well as footprints, have been discovered during archaeological investigations at and around the central Taklamakan Desert Yuansha Site (38°52′N, 81°35′E). Dating (14c and OSL) and landform study show that the present-day dry Keriya River once sustained an oasis human settle- ment in 2.6 ka BP, historically falling into the Spring and Autumn Period (716-475 BcE) of chinese history. The chronology and archaeological interpretations also show that some 400 years later, the local Keriya River channel had shifted 40 km southeast to sustain a Western Han (206 BcE-25 cE) Wumi settlement at the Karadun site. In the meantime, river-channel migration had allowed reoccupation of a site west of Yuansha city around 1.9 ka BP (abandoned again by 1.6 ka BP). The remains' chronology shows that this site was affiliated to Wumi culture and Eastern Han (24-220 cE) dynasty rule. Palaeoclimatic records indicate that the migrations of the river and oasis settlers between 2.7 and 1.6 ka BP were coeval with central Asian climate changes. Yuansha city was built just after the end of 2.8 ka BP glacier advances in western china, suggesting that release of more water during the subsequent glacier recession may have facilitated oasis development such that Iron Age European peoples could settle in the Tarim Basin. As shown from analysis of archeological remains, not only at Yuansha but also in other ancient cities in the Tarim such as Loulan and Jingjue (Niya), conditions around 1.6 ka BP were dry enough to cause oasis decline. Thus, the results reported here enhance our knowledge about environmental changes and their effects on human activities and cultural evolution in western china and will stimulate further interdisciplinary studies of landscape and oasis history in the Tarim Basin.

关键词：塔里木盆地克里雅河水文变化年代学 14c BP 迁移三角洲

^(14)c measurement of forest soils in Dinghushan Biosphere Reserve

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 1999年第3期44卷 251-256页

作者： SHEN chengde , LIU Dongsheng (LIU Tungsheng) , PENG Shaolin, SUN Yanmin , JIANG Mantao , Yl Weixi , XING changping , GAO Quanzhou , LI Zhi’an and ZHOU Guoyi Guangzhou Institute of Geochemisry, chinese Academy of Sciences, Guangzhou 510640, china Institute of Geology, chinese Academy of Sciences , Beijing 100029, china South china Institute of Botany, chinese Academy of Sciences, Guangzhou 510650, china Guannzhou Institute of Geochemisry Chinese Academy of Sciences Guanazhou China Institute of Geology Chinese Academy of Sciences Beijing China South china Institute of Botany Chinese Academy of Sciences Guangzhou China

Organic carbon in forest soils of Qingyunsi and Wukesong profiles can be divided into fast and slow components. Δ14c values of these profiles decrease with increasing of depth. The Δ14c values in 30—40 cm depth interval of Wukesong profile are decreasing sharply until a very low value,showing that a strong geological environment change occurred about 1 560 years ago. The 14c apparent ages of Wukesong profile show that the coniferous and broad-leaf mixed forests around Wukesong profile have been developing since 425 a BP, which is consistent with historical documents. The penetrating depths of "bomb 14c" in Qingyunsi and Wukesong profiles are 10 and 20 cm, respectively.

关键词： Dinghushan forest soil 14c tracing 14c apparent age.

Shifts of the Kuroshio axis over the last 20 000 years

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 1998年第12期43卷 1053-1056页

作者： Jian Zhimin Y. Saito Wang Pinxian Li Baohua chen Ronghua Tongji Univ Lab Marine Geol Shanghai 200092 Peoples R China Geol Survey Japan Marine Geol Dept Tsukuba Ibaraki 305 Japan chinese Acad Sci Nanjing Inst Geol & Paleontol Nanjing 210008 Peoples R China State Ocean Adm Inst Oceanog 2 Hangzhou 310012 Peoples R China

core 255 from the southern Okinawa Trough was selected to monitor the shift of the Kuroshio axis over the last 20 000 years. During the last glacial maximum the Kuroshio axis had ever shifted outside the Okinawa Trough. It entered the Okinawa Trough again at about 6 500 a BP, leading to abrupt increase of sedimentation rate, distinctly coarser sediment and remarkably increased abundance of foraminiferal indicators of the Kuroshio in the core. But, during about 4 000-3 000 a BP the abundance of the Kuroshio indicator Pulleniatina obliquiloculata sharply decreased again, indicating that the Kuroshio axis had ever shifted easterly for a short period or the Kuroshio was weakened and that moment.

关键词： Kuroshio paleooceanography AMS 14c dating foraminifera Okinawa Trough.

Hydrogeochemical characteristics of hot springs exposed from fault zones in western Guangdong and their ^(14)c age correction

在线全文

学校读者我要写书评

暂无评论

Journal of Groundwater Science and Engineering 2019年第1期7卷 1-14页

作者： WANG Hua MAO Xu-mei WANG Tao FENG Liang LIANG Li-li ZHU Dong-bo YANG Kai-ming School of Architecture and civil Engineering Xihua University School of Environmental Studies China University of Geosciences

Hot springs are natural exposed points of the hydrothermal system. The hydrogeochemistry of hot springs can be used to interpret the formation of the hydrothermal system; and the ^(14)c dating can be used to evaluate the renewability of the hydrothermal system. The hot springs exposed from fault zones in western Guangdong are classified as granite fissure water and clastic rock fissure water, which are sampled and tested. The results of water chemistry analysis show that hot spring water is mainly HcO_3-Na type in the beginning, while the mixing of seawater leads to the increase of cl^-. Hydrogen and oxygen isotopes indicate that these hot springs mainly come from atmospheric precipitation, and water-rock interactions produce oxygen isotope exchange reactions, where a significant "oxygen drift" phenomenon can be observed. The relationship between δ^(13)c and HcO_3^- indicates that there is a deep source of cO_2 "dead carbon" in hot spring water. This systematic error is not considered in the existing ^(14)c dating correction models. The ^(14)c age of the deep source "dead carbon" correction proposed in this paper is close to the ^(14)c age of the reverse chemical simulation correction, the Gonfiantinie model, and the Mook model. The deep source "dead carbon" correction method can improve the systematic error. Therefore, the ^(14)c age corrected by the deep source "dead carbon" may be more representative in terms of the actual age of geothermal water.

关键词： Hydrogeochemistry 14c age Deep source “dead carbon” Hot spring Western Guangdong

Super solar particle event around AD775 was found

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2014年第22期59卷 2736-2742页

作者： Dazhuang Zhou chi Wang Binquan Zhang Shenyi Zhang Ping Zhou Yueqiang Sun Jinbao Liang Guangwu Zhu Ji Wu National Space Science center Chinese Academy of Sciences

A rapid radiocarbon14c increase of 120/00in AD774–775 has been reported in cedar and oak tree rings.So far,the origin of the14c increase is still uncertain and the possible origin is either supernova or solar particle event.The most possible origin of14c increase is strong solar flares and coronal Mass Ejections(cMEs)with strong particles emission.comprehensive approaches to identify the strong historical solar particle events based on the rapid14c/10Be increase in tree/coral rings and ice cores,long duration strong auroras and geomagnetic storms are introduced.Evidence of the super auroras in AD775 was first found in a chinese chronicles Jiutangshu and it supports the views that the rapid14c increase and strong auroras around AD775 are most possibly caused by strong solar storms with intense particles emission.It was identified that the solar event around AD775 would be the strongest solar particle event in the past 11400 years.The discovery is significant for the research on the history of solar activities,space weather and forecast,radiation of solar energetic particles and protection.

关键词：太阳耀斑子事件日冕物质抛射太阳高能粒子粒子辐射太阳风暴 14c 放射性碳

小型加速器质谱测量高放废物中3H和14c的实验方法研究

在线全文

学校读者我要写书评

暂无评论

小型加速器质谱测量高放废物中3H和14C的实验方法研究

作者：唐俊森广西师范大学

学位级别：硕士

H和c是核设施排放的主要放射性核素,核设施中的H主要由H（n,γ）H、Li（n,α）H、B（n,2α）H和He（n,p）H反应产生;c由c（n,γ）c、N（n,p）c和O（n,α）c的中子诱发产生。H与c的定量测量可以反映退役核设施的辐照计量,对判断退役核设... 详细信息

H和c是核设施排放的主要放射性核素,核设施中的H主要由H（n,γ）H、Li（n,α）H、B（n,2α）H和He（n,p）H反应产生;c由c（n,γ）c、N（n,p）c和O（n,α）c的中子诱发产生。H与c的定量测量可以反映退役核设施的辐照计量,对判断退役核设施的辐照情况以及其对环境的影响有重要作用。同时,在生物医学、地质学以及核环境评估中,H与c都有广泛应用价值。本研究使用广西师范大学紧凑型200k V单级静电加速器质谱仪（GXNU-AMS）,主要开展了高放废物中辐照石墨积累的H和c的浓度定量实验。研究的主要内容如下:（1）H与c同时分离纯化制样装置的建立及制样方法研究。装置设计思路为将初始样品完全氧化燃烧,将H氧化燃烧成HTO,c氧化燃烧成cO,再通过真空制样系统分别回收。实验收集的HTO将采用锌钛法制备,cO主要采用锌铁法回收,制成H靶和c靶后供加速器测量。由于需要同时回收样品中的H和c,故而设计了一套专门用于制备高放射性样品的真空制样系统,能同时满足H和c的收集制备。（2）对采集的某重水堆辐照石墨进行加速器质谱测量和分析。实验选取了辐照石墨柱的10个位置进行H与c的放射性定量测量。辐照石墨样品经H和c同时回收真空系统制备样品,生成氢化钛靶样和石墨靶样后利用加速器质谱仪进行H和c测量,得到H/H丰度比和c/c丰度比,通过与标样对比,归一化处理后得最终放射性活度,进而获取退役核设施的放射性活度情况。（3）加速器质谱测H和c条件的调试与优化。使用商业氢化钛和商业石墨进行AMS测H和c调试,H选用H和c作为导航束流模拟传输,c则选用c束流进行模拟传输。测量结果给出仪器的H本底值为（1.23±0.17）×10;c的本底值为（2.23±0.045）×10。H和c的本底值已达国际同类产品水平。以氚水（5.426×10～3Bq/g）和草酸（NIST,USA）作为标准样品,经样品制备系统分别制备成氢化钛和石墨单质后,由广西师范大学的小型AMS系统测量。H样品的H引出束流大于10μA,c的引出束流大于40μA,均已满足AMS的测量需求。本工作经实验室制样及加速器测量分析,最终实现了H与c的同时回收,成功分析出辐照石墨中的H与c的放射性活度。与液闪测量结果对比,加速器质谱能更精确的测量H与c的放射性活度,并且所需样品量少（毫克级别）,测量灵敏度更高。本文提供了一种H与c同时回收的方法,这种方法不仅可以应用于核石墨样品测量,还可以用于有机样品如树心样品的测量,同时为双示踪同位素H与c同时标记的实验提供了制样测量方法。

关键词： 3H 14c 3H-AMS 辐照石墨

秦山核电基地外围植被中^(14)c水平分布研究

同方学位论文库评论

在线全文

同方学位论文库

学校读者我要写书评

暂无评论

原子能科学技术 2012年第B9期46卷 683-688页

作者：王钟堂向元益郭秋菊王侃龚传德北京大学物理学院核物理与核技术国家重点实验室北京100871 浙江省辐射环境监测站浙江杭州310012

为了解秦山核电基地外围14 c的水平分布与规律,本文采用加速器质谱法(AMS)对秦山核电基地外围6.5km以内的植物样品(苔藓、松针)与食物样品中的14 c比活度进行测量。测量结果显示:苔藓样品的14 c比活度范围为223.0～265.6Bq/kg c(本底为2... 详细信息

为了解秦山核电基地外围14 c的水平分布与规律,本文采用加速器质谱法(AMS)对秦山核电基地外围6.5km以内的植物样品(苔藓、松针)与食物样品中的14 c比活度进行测量。测量结果显示:苔藓样品的14 c比活度范围为223.0～265.6Bq/kg c(本底为223.8Bq/kg c),14 c比活度随距排放点距离的增加呈降低的趋势,在距排放源6.5km处达到了本底水平。与松针相比,苔藓更适合做核设施14 c排放的指示植物。苔藓样品的14 c比活度分布规律表明,14 c气态污染物在大气中的扩散受地形和风向因素的影响。食物样品的14 c比活度比参照样品高8.5～13.0Bq/kg c(大米样品除外),给当地公众带来的附加剂量为0.5μSv/a。

关键词： 14c 秦山核电基地 AMS 比活度分布剂量