CAJ | 학술논문

运用实验模拟的手段，对铀(U)、钍(Th)在碳酸钙-海水界面的附着行为进行了初步研究，通过测定相关的分异系数(D)定量评估了文石和方解石两种碳酸钙矿物对U和Th的捕集作用。实验结果显示，不仅 U 和 Th 之间存在显著差异，而且两种碳酸钙矿物之间也存在明显不同。U 介于碳酸钙和海水之间的分异系数(DU)分别在1.5~3.5(文石)和0.04~0.19(方解石)区间内变化，分异行为非常微弱但其分异系数随着碳酸钙沉淀速率的增加而逐渐上升。这表明U元素主要是以共沉淀的方式进入到文石或方解石沉淀中，但由于其在海水溶液中主要以2223UO (CO )n? n的形式存在，因而只能以占据晶格缺陷的方式进入碳酸钙。与之相反的是，文石和方解石都对 Th 表现出极强的捕集能力，所测定的分异系数(DTh)分别在240~6330(文石)和430~6160(方解石)范围内变化，但DTh与碳酸钙沉淀速率之间无明显关联。Th 在碳酸钙表面的附着行为可界定为单纯的吸附作用，这一行为应与 Th 主要以 Th(OH)4的形式赋存于溶液中有关。
운용실험모의적수단，대유(U)、토(Th)재탄산개-해수계면적부착행위진행료초보연구，통과측정상관적분이계수(D)정량평고료문석화방해석량충탄산개광물대U화Th적포집작용。실험결과현시，불부 U 화 Th 지간존재현저차이，이차량충탄산개광물지간야존재명현불동。U 개우탄산개화해수지간적분이계수(DU)분별재1.5~3.5(문석)화0.04~0.19(방해석)구간내변화，분이행위비상미약단기분이계수수착탄산개침정속솔적증가이축점상승。저표명U원소주요시이공침정적방식진입도문석혹방해석침정중，단유우기재해수용액중주요이2223UO (CO )n? n적형식존재，인이지능이점거정격결함적방식진입탄산개。여지상반적시，문석화방해석도대 Th 표현출겁강적포집능력，소측정적분이계수(DTh)분별재240~6330(문석)화430~6160(방해석)범위내변화，단DTh여탄산개침정속솔지간무명현관련。Th 재탄산개표면적부착행위가계정위단순적흡부작용，저일행위응여 Th 주요이 Th(OH)4적형식부존우용액중유관。
Using the constant addition system, the uptake of uranium and thorium at the interface of CaCO3-seaw-ater was investigated. Significant differences were observed not only between U and Th but also between aragonite and calcite. Partition coefficients of U (DU) between CaCO3 and seawater were determined to range from 1.5 to 3.5 for aragonite and 0.04 to 0.19 for calcite. The partitioning of U is very weak, but the value of DU was observed to increase with increasing precipitation rates of aragonite or calcite. It suggests that U was incorporated into CaCO3 precipitates via coprecipitation. However, because U(VI) is present in seawater in the form of 2 22 3UO (CO )n? n , the incorporation of U(VI) could only be achieved by the occupation of defect sites. As compared to U, Th could be strongly gathered by both calcite and aragonite. The partition coefficients of Th (DTh) between CaCO3 and seawater range from 240 to 6330 for aragonite and 430 to 6160 for calcite. However, there is no correlation between DTh and CaCO3 precipitation rates. The uptake of Th at the interface of CaCO3-seawater was achieved simply via adsorption. Such behavior of Th(IV) should be related to dominance of Th(OH)4 in our solutions.