Su Weigang, Ma Yujun, Wang Qiugui, Yan Qiongxiong, Lu Xiaohang, Ma Zhe, Yi Lei, Liu Xiaobao, Chen Fuhong, Han Fengqing, Xu Zhengfan
Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Chinese Academy of Sciences and Qinghai Provincial Key Laboratory of Geology and Environment of Salt Lakes, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining, 810016, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Qinghai Earthquake Agency, Xining, 810001, China.
Key Laboratory of Tibetan Plateau Land Surface Processes and Ecological Conservation, Ministry of Education, Academy of Plateau Science and Sustainability, Qinghai Normal University, Xining, 810008, China.
J Environ Radioact. 2022 Jan;241:106771. doi: 10.1016/j.jenvrad.2021.106771. Epub 2021 Nov 11.
Natural radium isotopes have been widely used to study groundwater discharge in different systems. Therefore, it is of great significance to understand the desorption behavior of radium isotopes on sediments to trace water-land exchange processes. However, there is very limited studies observing the desorption Ra isotopes to lake water of the brine lake. Ra desorption experiments with different salinities and particle sizes were carried out by collecting samples of brackish water from Qinghai Lake, brine from Dabuxun Lake and river sediments entering the lakes. The results show that the desorption activity of Ra from the river sediments to lake water of Qinghai Lake is 0.2 dpm/g when the salinity is 10.07‰. The maximum desorption activity of Ra from river sediments to lake water of Dabuxun Lake is 0.195 dpm/g at a salinity of 40.81‰. A salinity of 41.81‰ and particle size of 16.28 μm are the threshold points affecting the desorption behavior of Ra. When the salinity is less than 40.81‰, the desorption activity of Ra increases linearly with increasing salinity. When the salinity is greater than 40.81‰, the desorption activity of Ra decreases nonlinearly with increasing salinity and tends toward a stable low value. When the particle size is larger than 16.28 μm, the small particle size promotes desorption. The smaller the particle size is, the greater the desorption activity is. When the particle size is less than 16.28 μm, the small particle size inhibits desorption. The smaller the particle size is, the smaller the desorption activity. The co-precipitation of Ra with supersaturated Ca, SO and other ions may be the main reason for the threshold point of salinity and particle size in Ra desorption process in salt lake system.
天然镭同位素已被广泛用于研究不同系统中的地下水排放。因此，了解镭同位素在沉积物上的解吸行为对于追踪水陆交换过程具有重要意义。然而，观察卤水湖镭同位素向湖水解吸的研究非常有限。通过采集青海湖微咸水、大布逊湖卤水以及流入湖泊的河流沉积物样本，进行了不同盐度和粒径的镭解吸实验。结果表明，当盐度为10.07‰时，河流沉积物中镭向青海湖湖水的解吸活度为0.2 dpm/g。在盐度为40.81‰时，河流沉积物中镭向大布逊湖湖水的最大解吸活度为0.195 dpm/g。盐度41.81‰和粒径16.28μm是影响镭解吸行为的阈值点。当盐度小于40.81‰时，镭的解吸活度随盐度增加呈线性增加。当盐度大于40.81‰时，镭的解吸活度随盐度增加呈非线性降低并趋于稳定的低值。当粒径大于16.28μm时，小粒径促进解吸。粒径越小，解吸活度越大。当粒径小于16.28μm时，小粒径抑制解吸。粒径越小，解吸活度越小。镭与过饱和的钙、硫酸根等离子的共沉淀可能是盐湖系统镭解吸过程中盐度和粒径阈值点的主要原因。
