Distribution of Ra-223 and Ra-224 in the Bo Sea embayment in Tianjin and its implication of submarine groundwater discharge

作者：Liu, Lingling^*; Yi, Lixin; Cheng, Xiaoqing; Tang, Guoqiang

来源：Journal of Environmental Radioactivity, 2015, 150: 111-120.

DOI：10.1016/j.jenvrad.2015.08.008

• Short-lived radium isotopes
• Advection-diffusion process
• Residence time
• SGD
• Bo sea embayment

Submarine groundwater discharge (SGD) is now recognized as an important pathway between land and sea. In this study, in order to analyze the distribution of naturally occurring short-lived radium isotopes and the relative SGD effect in Bo Sea embayment, Ra-223 and Ra-224 were measured in three parts of the embayment with the radium-delayed coincidence counting (RaDeCC) system. Subsequently, the mixing process was studied by the calculation of diffusion coefficients (K-x and K-z) and advection velocities (V-x and V-z) based on the 2D advection-diffusion model. Additionally, the apparent residence ages and SGD flux were quantified based on the Ra-224 and Ra-223 activities. The results showed that the Ra activities exponentially decreased with the distance offshore, and both the K-x and V-x took the order of northern part > southern part > middle part. In vertical direction, there was the maximum value of Vz and minimum K-z in middle part and the maximum K-z and minimum V-z in southern part. The average ages for the northern, middle and southern parts were 4.28, 7.38 and 3.73 days, respectively. The final SGD flux yielded by Ra-224 was 0.09, 0.01 and 0.03 m d(-1) in the northern, middle and southern parts, respectively. The SGD flux yielded by Ra-223 was 0.08, 0.01 and 0.03 m d(-1) in northern, middle and southern parts, respectively.

• 出版日期2015-12
• 单位南开大学