Size-fractionated uranium isotopes in surface waters in the Jiulong Estuary in China   总被引：1，自引：1，他引：0  

L&#; E  ZHANG Lei  CHEN Min  QIU Yusheng  XING N  YANG Weifeng  LI Yanping  HUANG Yipu 《海洋学报(英文版)》2008,27(1):29-41

Surface water was collected from the Jiulong Estuary for determination of activity concentrations of uranium isotopes in different size fractions, namely, greater than 53, 10 -53, 2 - 10, 0.4 -2 μm, 10 000 u -0.4 μm and less than 10 000 u fractions by microfihration and cross-flow uhrafiltration technologies. Results indicated that most of the dissolved uranium （ 〈 0.4 μm） exis- ted in the low molecular mass fraction （ 〈 10 000 u）, and the colloidal uranium-238 （10 000 u -0.4 μm） only contributed less than 1% of the dissolved uranium-238. The fractions of colloidal uranium in the dissolved phases decreased with the increasing sa- linity. A positive linear relationship between uranium-238 activities and salinities was observed for the dissolved, colloidal and low molecular mass fractions, indicating a conservative behavior of uranium in the Jiulong Estuary. In the particulate phases （ 〉 0.4 μm）, the partitioning of uranium isotopes among different size fractions was controlled by the partitioning of particle concentrations. In the regions with salinities below 20, the partitioning of uranium-238 among different size fractions was as follows： 10 - 53 μm 〉 2 - 10 μm 〉 0.4 - 2 μm greater than above 53 μm. However, the order at the offshore station with salinities above 30 changed as follows ： 0.4 - 2 μm 〉 10 - 53 μm 〉 2 - 10 μm greater than above 53 μm. The fraction of the 0.4 - 2 μm particles increased at the offshore station, suggesting the increased contribution of the authigenic uranium. The activity ratio of uranium-234 to uranium-238 in the dissolved phases, including the low molecular mass fraction and the colloidal fraction, was larger than unity, showing the occurrence of excess uranium-234. In contrast, the activity ratio of uranium-234 to uranium-238 in all size fractions of the particulate phase was close to the equilibrium value （1.0）. The observed different values of the activity ratio of uranium-234 to uranium-238 in the dissolved phase and the partic  相似文献   

The investigation on particulate organic carbon fluxes with disequilibria between thorium-234 and uranium-238 in the Prydz Bay, the Southern Ocean   总被引：1，自引：0，他引：1  

HE Jianhu  MA Hao  CHEN Liqi  XIANG Baoqiang  ZENG Xianzhang  YIN Mingduan  ZENG Wenyi 《海洋学报(英文版)》2008,27(2):21-29

Dissolved and particulate thorium-234, particulate organic carbon in the upper 150 m of water columns from five stations in the Prydz Bay, the Southern Ocean were determined during the 22nd Chinese National Antarctic Research Expedition （from November 2005 to March 2006 ）. The disequilibria between thorium-234 and its parent uranium-238 in upper layer was used to derive the averaged residence time of thorium-234, which decreased along with the latitude to the south and a minimum value, 1 - 8 d for particulate thorium-234 and 29 - 48 d for dissolved thorium-234, appeared at the medium latitude station, and the export fluxes of thorium-234 were calculated too and ＇a maximum value, 0. 35 -0. 63 Bq/（m^3 · d） for the particulate thorium-234 and 0. 44 -0. 65 Bq/ （m^3 ·d） for the dissolved thorium-234, appeared at the same station. The export fluxes of particulate organic carbon at different water columns were derived by two methods with irreversible scavenging model, and the averaged values were 104. 7 mmol/ （ m2 · d ） （ E method） and 120. 6 mmol/（ m2·d ） （ B method ）, respectively, indicating that a relatively high new production would exist in summer in the Prydz Bay where it will play a potential significant role in sequestering the absorption CO2 to deeper ocean.  相似文献   

贝壳生物矿化的研究进展   总被引：4，自引：1，他引：3  

张文兵  姚春凤  麦康森 《海洋科学》2008,32(2):74-79

生物体硬组织是高度结构化多功能复合材料的绝佳典范.这些硬组织包括骨组织(骨和茸角)、牙组织(牙本质和牙釉质)、棘皮动物骨骼单位、海绵动物骨针和贝类贝壳.在遗传因素的控制下,生物体通过节能和环境友好途径合成这些生物复合材料.这些有关生物硬组织功能和结构的研究,在医学和工程学上找到了广阔的应用前景.一方面使更好地促进骨骼和牙齿的再生成为可能.  相似文献   

山东五莲七宝山窑头隐爆角砾岩筒矿化特征及意义          下载免费PDF全文

于兆安  李彩霞  张立荣 《山东国土资源》2008,24(5):27-29

五莲七宝山地区岩浆活动频繁,具有多期次岩浆活动。环状断裂与辐射状断裂发育,形成七宝山复式火山机构。隐爆角砾岩是火山活动的产物,具有良好的成矿机制和控矿作用,窑头隐爆角砾岩筒成矿时代为燕山晚期。对窑头隐爆角砾岩筒的产状、分布、规模、围岩蚀变等地质特征进行了分析,推断窑头铜（金）矿为隐爆角砾岩型低温热液小型矿床。  相似文献   

浅成磷钙土中的铀     

朱佛宏 《海洋地质前沿》2008,24(10):42-42

磷钙土被广泛用于生产肥料的原料或直接用作肥料。对它的研究非常深入,包括分析微量元素组分。发现沉积岩中微量元素的一般分面规律和从磷钙土的实际农业化学应用观点出发是很重要的,因为在其组分中的部分微量元素是微量肥料,而部分（例如铀）则在生态上是危险的。磷钙土是获得铀的重要矿石,美国大部分铀正是从磷钙土中获取的。  相似文献   

略论青城子矿田矿化分带性     

陈江 《国土资源》2000,(3)

青城子矿田是一个大型金、银多金属综合矿田,矿田内具有（铜）铅锌－银－金的矿化分带现象。从含矿原岩建造－浊积岩建造、变质作用、岩浆作用、韧性剪切作用以及矿质分异作用角度对青城子矿田的矿化分带性做了初步研究,认为青城子矿田的矿化分带性是多种因素造成的。对矿田分带性的研究有利于青城子矿田乃至辽东地区的金、银多金属矿产找矿与勘查。  相似文献   

试论大厂锡多金属矿田矿化蚀变分带特征     

杨斌  罗德宣  张起钻 《南方国土资源》1999,12(3):17-23

大厂矿田矿化蚀变分带特征十分明显, 在水平方向, 整个矿田可分为西、中、东３ 个矿带。西、东矿带主要产出锡石—硫化物型矿床, 围岩蚀变类型主要有硅化、钾长石化、电气石化、绢云母化、碳酸盐化等。中矿带主要分布矽卡岩型锌铜硫化物矿床, 并有锑钨石英脉型矿床叠加其上。整个矿田矿化蚀变分带又具明显的不对称性, 并且每一种矿化类型又表现出各自的分带特点。大厂矿田的总体矿化蚀变分带特征与传统的顺向或逆向分带不同, 反映了多成因、多期次叠加成矿及蚀变的特点  相似文献   

用于直接测量空气中氡和钍射气浓度探测器的基本原理     

白云生  谈成龙 《国外铀金地质》1995,12(3):273-275

本文介绍了一种连续监测空气中氡同位素浓度的新技术。与其他方法相比，该技术可直接测量＾２２０Ｒｎ、＾２２２Ｒｎ衰变的α粒子。  相似文献   

在波兰上西里西亚煤盆地古生代老基底发现金属矿床的可能性     

Niec  M 盛继盛 《国外矿床地质》1995,(1):12-15

  相似文献   

韧性剪世带中含金石英脉的就位机制     

刘俊来 《吉林地质》1993,12(3):16-23

  相似文献