南海近海水中U,90Sr,137Cs,3H和总β放射性分布

1 水样的采集和分析 1.1 水样的采集和预处理 在1988～1990年间,我们对南海近海(包括大亚湾核电站周围海区)进行了放射性本底监测。共布设11个采水站位(见表1),每年3～4月份采水样一次,每站均采其表层海水100L,将所采海水装入塑料桶,并按每升海水加1ml浓HCL的比例进行酸化处理。 1.2 海水中放射性物质的分析     

青岛市7Be, 210Pb 和210Po大气沉降通量的测定

运用本实验室建立的大气沉降中7Be,210Pb的γ谱分析方法和210Po的α谱分析方法,测定了青岛大气沉降通量.结果表明,青岛市2002年4～11月大气沉降的7Be和210Pb通量平均为1.67和0.32 Bq/(m2·d);2004年5～9月7Be,210Pb和210Po通量平均值为2.15,0.51和0.083 Bq/(m2·d).     

EFFECTS OF 137Cs, 131I AND 32P ON THE EMBRYONIC DEVELOPMENT OF MUSSEL AND SEA-URCHIN

Preliminary investigations were recently made in laboratory on the effects of low-levelradioactivity contaminated by radioisotopes using embryonic of mussel (Mytilus edulis) andsea-urchin (Hemicentrotus pulcherrimus) as the material. The gametes and various stagesof fertilized eggs of mussel and sea-urchin were maintained in seawater contaminated with~(137)Cs (~(131)I or ~(32)P) over the concentration range 10~(-10)Ci/L to 10~(-2) Ci/L. The effects     

Measurement of 224Ra, 226Ra and 228Ra in seawater using Mn-fiber adsorption-γ spectrum method

I~IOXThe half-lives of natural radioactive nuclides "'Ra, 226Ra and 228Ra are 3. 66 d, 5. 76 a,1600 a respectively, hence, the marine process with various time scales can be researched by taking these nuclides as tracers. Because these nuclides can be determined by measuring them or theirdaughters' a,g, y-rays, they have been applied extensively in oceanography research. Huang(1996), Huang et al. (1996 a,b) and Chen (1996) have given reviews on it.Since the contents of "'Ra, 226Ra and 228…     

极高温度下17O(p,α)14N与17O(p,γ)18F两反应道分支比的计算

本文计算在极高温度(非共振能量情况)下     

海水中137Cs/90Sr的比值

在海洋环境中,放射性核素~(90)Sr和~(137)Cs的测定占有重要的位置。 研究~(137)Cs/~(90)Sr比值,有助于了解这两个核素的地球化学过程、分馏现象以及在海洋中的归宿。同时,还可以根据其比值和其中一个核素的含量,推算出另一个核素的浓度。 一、核爆炸后的~(137)Cs/~(90)Sr比值 1965年,Harley等人根据百万吨级的核     

海水中的18O/16O比值及其应用

氧是地球上最丰富的元素,自然界中的氧元素实际上是多个稳定同位素(~(16)O,~(17)O,~(18)O)的混合物,它们的丰度相差很大,~(18)O占0.1995％,~(16)O占99.763％,~(17)O只占0.0375％。由于氧同位素丰度大,质量差也大,因此,可以测定~(18)O/~(16)O的比值,并且通过比值的变化了解     

南海全新世珊瑚礁AMS14C,230Th/234U和ESR年龄的对比研究

用~(14)C(AMS和稀释技术),铀系和ESR方法对南海珊瑚礁进行了测年对比研究,表明这些珊瑚礁形成于全新世早、中期。此外,对测年方法的一些有关问题也进行了讨论。     

黄河下游及河口区表层沉积物中U,Ra,Th,40K和137Cs的测定

本文从地球化学和环境保护的角度,用8180—4Kγ谱仪直接测定方法确定了天然放射性元素U,Ra,Th,~(40)K,及人工核素~(137)Cs的含量,讨论了它们的分布特点及其影响因素,指出了河口区与下游段元素变化的差异及其制约条件。     

光照、温度对小球藻吸收60Co,137Cs影响的实验研究

本文研究了光照、温度对小球藻(Chlorella sp.)吸收~(60)Co和~(137)Cs以及对生长的影响。实验是在~(60)Co,~(137)Cs混合示踪条件下进行的,结果表明:(1)小球藻对~(60)Co有着很高的累积能力,而对~(137)Cs的累积能力较低;(2)光照无论对藻吸收~(60)Co还是吸收~(137)Cs的浓缩系数的影响都是全光照>半光照>黑暗;(3)温度升高藻吸收~(60)Co的浓缩系数增大;(4)小球藻在全光照、28℃时的生长最好,而在黑暗、35℃时的生长最差。     

A study on the distribution of 210Pb, 226Ra and total β radioactivity in estuary sediments

Determination on the content variation of 210Pb, 226Ra and total β radioactivity in estuary sediments of the Jiulongjiang River and the Changjiang River were made to study distributions of natural radioactive substances in the areas studied. Sources of radioactive substances were determined, and the transportation of bottom waters and sediments in the areas was searched according to the distributions.     

THE TRANSFER OF 137Cs, 60Co ALONG THE FOOD CHAIN OF PLATYMONAS BRACHIONUS AND TILAPIA

The transfer of 137C3, 60Co along Platymonas sp., Brachionus plieatilis Muller and Tilapia mos-sambica Peters was studied by using the tracer methods of both 137C3 and 60Co with Ge (Li) Gamma ray detector and S-80 type multichannel-analyser for measuring the radioactivity of the sample. The experiment was carried out in four groups and the period of the experiment was fifteen days. It was found that 60Co could be transferred along seawater→Platymonas→Brackionus→Tilapia, and that 137C3 could only be transferred from seawater to Platymonas. 137C3 was not accumulated by Brachionus in any group of the experiment. Brachionus ingested 60Co mainly from Platymonas, when 60Co was ingested by Tilapia; Brachionus played an important role in the transfer and the Tilapia ingested 137C3 mainly from seawater.     

THE METABOLISM OF 60Co AND 137Cs BY ARCA GRANOSA LINNUS

The pathway by which "Co and 137C3 got into Area, and the type of uptake in animal were studied. The results showed that 60Co was taken up by gill and was transferred quickly to other organs through blood. There are more uptake pathways for 137Cs. The uptake of 60Co by Arca was mainly active transfer and the energy comes mainly from the process of biotic oxidation. On the contrary, the uptake of 137C3 by Arca was mainly a passive transfer, and for most organs the exchange through body-wall was a significant factor.     

基于7Be、210Pb和210Po的厦门岛沿岸地区大气过程示踪研究及辐射剂量评估

本研究测定了2015年1~7月厦门市大气气溶胶中的7Be、210Pb和210Po,利用多核素联合示踪研究了相关的大气过程.结果表明7Be和210Pb在1、3和4月份具有较高的活度水平和较大的活度变化范围,在6~7月份降低到相对较低的活度水平和一个相对较小的变化范围,不同的气团来源、对流混合及清除机制是其主要的控制因素.相对于7Be,7Be和210Pb同位素对对臭氧(O3)具有更好的相关关系.基于210Pb和210Po的数据计算出厦门市大气气溶胶停留时间为21~188 d,平均值为87 d.通过辐射剂量评估发现这3种放射性核素对人体所产生的年待积有效剂量仅为5.31μSv,近似为天然辐射本底的千分之一.     

不同潮时对厦门湾水体中234Th/238U不平衡的影响

厦门海水体中^234Th/^238U不平衡的时间序列数据表明，无论是溶解态、颗粒态^234Th还是总^234Th,相对于母体^238U均严重亏损，呈现出与开阔大洋水明显不同的特征。溶解态、颗粒态^234Th的停留时间介于0．5－41d之间，其中低潮时停留时间比高潮时小2－4倍，证实近岸海域具有强烈的清除、迁出作用，且潮汐变化对海域颗粒动力学特征有重要影响。^234Th停留时间与总悬浮颗粒物浓度（TSM）、Ch1.α的关系则表明，近岸海域元素的清除、迁出作用主要受陆源颗粒物输送的影响，与生物活动关系并不密切。此外，非稳态与稳态清除模型结果的对比证明，稳态模型对于具有强烈清除、迁出作用的近岸海域是适用的。     

渤海近岸区表层沉积物中U,Ra,Th,40K,137Cs的Ge(Li)γ谱仪测定及地球化学研究

海洋环境中存在着大量的天然和人工放射性同位素,研究其含量变化及存在形式,对于同位素地球化学、沉积化学、地质年龄、水团运动和环境保护均有重要意义。随着科学的进步和仪器的更新,近年来这方面的研究获得了迅速的发展。     

长江口及其邻近陆架沉积物中226Ra和210Pb的分布特征

本文利用放射化学分析法测定了长江口及其邻近陆架沉积物中~(226)Ra和~(210)Pb的含量。结果表明,在该海区的沉积物中,~(226)Ra含量的水平分布随经度增加而直线下降,而~(210)Pb含量的水平分布则随经度增加而直线上升,二者形成明显的同步反向分布。