准噶尔无叶豆的地理分布、群落学特征及生物生态学特性

准噶尔无叶豆(Eremosparton songoricum(Litv.)Vass.)是国家级保护植物。对该植物地理分布、群落特征及生物生态学特性进行的研究表明:①准噶尔无叶豆分布区和生态幅狭窄,在我国仅斑块状分布于新疆古尔班通古特沙漠腹地局部地段及沙漠东南缘的部分流动沙地上;②群落中包含植物14科33属37种,可划分为7个地理区系成分,其中,温带分布型属占75.76%。依据群落组成及外貌,划分为5个群丛,主要特点为:不表现为显著的景观植被,且小面积出现;结构简单,层次单调,植物组成均系适沙和耐沙的种类;整个群落以先锋性为特征。此外,群落不稳定,有逐步被其他类型的、相对稳定的群落所替代的趋势,具有时空分布的"暂时性";③具有"花多果少"的果实产量格局,2005年结实率为(15.36±2.16)%。呈"水泡状"或"干瘪状"的种子比率达(16.2±2.31)%,虫蛀率达(16.92±2.69)%;④种子向幼苗转化率低。依靠超强的水平根茎克隆能力来扩展种群空间。经综合分析,认为准噶尔无叶豆对生境高度专一,人为干扰破坏所带来的生境丧失将使该种受胁状态加剧。对该物种进行保护首先应加强现有生境的就地保护,减少人为破坏;其次,积极开展迁地保护生物学研究,建立苗圃,营造人工种群

A Study on the Method for Separation and Determination of Pa-231 from Manganese Nodules

着重研究了锰结核样品中Pa的分离条件,建立了~(231)Fa分离的流程。锰结核样品加入示踪剂~(232)U-~(228)Th和~(233)Pa,在 0.05 mol/l HF 存在下用盐酸和硝酸溶解,离心除去不溶残渣,溶解液蒸干用1mol/l HNO_3提取,在pH=7 下使 Fe(OH)_3 沉淀后进行Th-Pa-U 的离子交换色层分离。Pa用 0 mol/l HCl+0.05 mol/l HF 洗脱,洗脱液用0.5 mol/l TTA-苯萃取纯化和制源,比较了~(231)Fa α能谱法和α计数法测试的结果,实测了一个碳酸盐标准样品的~(231)Fa/~(235)U 法年龄为(85±10)×10~3 y与~(230)Th/(234)u法的平均年龄(84±4)×10~3 y 是一致的。Pa的化学回收率为78～86％。 【英文摘要】 The separation conduction for Pa from inanganese nodules has beea studied and a procedure has been established for separation and determination of Pa.After adding U232-Th223 and Pa-233 as tracer manganese nodule samples are dissolved with HC1 and HNO3 in the presence of 0.05mol/l HF, and centifuged to isolate insoluble residues off. Dissolved solution is then eraporaed to dryness and taken up with 1 mol/1 HNO3, Subsequently Th, Pa, U are coprecipitaed by Fe(OH)3 at pH=7, and separoted on the anion exchanger..

九龙江—厦门湾河口区溶解~(226)Ra的分布

利用锰纤维富集和直接射气法测定海水中~(226)Ra的方法,对九龙江-厦门湾溶解~(226)Ra的分布进行了一次调查。结果发现在河口区内溶解态的~(226)Ra呈非保守行为,与世界上几大河流河口区~(226)Ra的行为极为相似。在海门岛附近的水体中(S≈9)发现溶解态~(226)Ra浓度最大,其值为0.598dpm/dm~3,说明咸淡水在此处混合最激烈。本河口区溶解~(226)Ra的最大值比Mississippi河的值小,比其他河流的值大2～5倍。国家自然科学基

STEPWISE SEPARATION AND DETERMINATION OF (231)~pa ISOTOPES OF U AND Th IN MARINE SAMPLES

本文结合已报道的U,Th分离方法和~(231)Pa分离条件建立了Th-Pa-U联合分离流程和测试技术,并用以分离测定一个锰结核和一个深海沉积物样品中的~(231)Pa,U和Th同位素含量的深度分布。用~(231)pa_(ex),~(230)Th_(ex)和~(230)Th_(ex)/~(232)Th法分别计算该锰结核的生长速率为1.5,0.9和1.5mm/Ma。U,Th和~(231)Pa的化学回收率(％)分别为40—80,80—92和60—86。 【英文摘要】 Combing the published method of determing isotopes of U and Th with the condition of separating 231Pa, a new method was established to separate and determinate 231Pa, isotopes of U and Th simultaneouly.The profiles of U, Th and 231Pa in a deep-sea manganese nodule and in a sample of the deep-sea sediment were determined, respectively, using the method. The growth rates of the manganese nodule were 1.5, 0.9 and 1.2mm/M.yr. separately, through the methods of 231Paex, 230Thex and 230Thex/232Th. The recoveries ..

海洋沉积物中~(226)Ra、~(210)Pb和U、Th同位素联合分离测定的研究

本文建立了一个联合分离测定沉积物中~(226)Ra、~(210)Pb和U、Th同位素的方法,讨论了这些核素之间的分离、纯化以及影响化学回收率的因素,报道了此法的一些应用。国家教委博士点科学基

湄洲湾天然放射性核素地球化学行为

本文通过湄洲湾秀屿站沉积物和海水中放射性含量的测定,讨论若干放射性核素的地球化学行为。 我们于1985年11月3日在北纬25°12.3′、东经119°0.4′用箱式采样器取沉积物样, 【英文摘要】 Abstract The geochemical behaviors of same natural radionuclides in Meizhou Bay have Leen studied. Based on the profiles of Fe & Ma ia the core, the relationship between the change of redox conditions and the distributions of Uranium have been discussed

THE SEPARATION OF HIGH PURITY ~(233)Pa FROM ~(237)Np

一、引言~(231)Pa是AcU(~(235)U)天然放射系的一个重要成员。在海洋地球化学和地质年代学研究中,它是一个非常重要的核素。但可作为~(231)Pa分离用的产额示踪剂的核素只有~(233)Pa,它是β-γ发射体,半衰期短(27.0 d)。因此如果能够简便地制得示踪剂~(233)Pa,对~(231)Pa年代学的研究和应用以及对镤化学和放射化学的研究无疑是个促进。 【英文摘要】 A new method is presented for high purity ~(233)Pa separation from ~(237)Np usingTTA (2-thenoyltrifluoroacetone) as extractant. ~(233)Pa is extracted with an equalvolume of TTA in benzene from 8 mol/1 HNO_3 solution containing ~(237)Np, thenwashed the organic phase with 8 mol/1 HNO_3 three times. Subsequently, ~(233)Pa isreexacted into an equal volume of 1 mol/1 HNO_3-0.1 mol/1 HF from organicphase. The aqueous phase is washed by 0.5 mol/1 TTA in benzene. After all HFis removed by evaparation, and the resid..

The Separation of U, Th And the Determination of U-Series Age in the Geological Carbonate Samples

本文报道了我们测定两个国内铀系碳酸盐标准样的结果。叙述了所用的α能谱技术和铀、钍化学分离流程。结果表明,我们所测得的铀、钍α谱的能量分辨率为31—40keV,铀—钍的互相分离比较完全;获得的各项数据与十个实验室数据的平均值基本一致。 【英文摘要】 This laboratory is involved in Uranium-Series Intercomparison Project in China, for standardizing the 232U concentration in the 232U-228Th spike solution and determining various U,Th isotope ratios of two carbonate samples from which their U-series ages could be calculated. Various data obtained by us were well agreeable with the mean values recorded by all the laboratories concerned.The present paper describes the alpha spectrometry technique used for determining U, Th isotopes and U, Th chemical separatio..

湄州湾沉积物的混合速率和沉积速率的研

本文对近岸海域~(210)Pb年代学的双层模式的适用性进行了讨论,并成功地用于湄州湾沉积速率和混合速率的研究,讨论了由~(210)Pb和~(137)Cs求出的湄州湾沉积速率之间的差别,用过剩~(234)Th测定了沉积物表层的混合速率

A NEW METHOD FOR SEPARATION AND DETERMINATION OF U AND Th IN DEEP-SEA MANGANESE NODULES

A new and simple method for separation and determination of U and Th in manganese nodules has been developed. The results show that the addition of NH4NO3 to the dilute HNO3 medium increases the selectivity of anion-exchange separation of U and Th. The simple procedure and high recoveries of the method make it valuable to the analyses of U and Th in manganese nodule