Liu Lingling, Yi Lixin, Cheng Xiaoqing, Tang Guoqiang
College of Environmental Science and Engineering, Nankai University, Mengminwei Building 405, 94 Weijin Road, Nankai District, Tianjin, China.
J Environ Radioact. 2015 Dec;150:111-20. doi: 10.1016/j.jenvrad.2015.08.008. Epub 2015 Aug 28.
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, (223)Ra and (224)Ra 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 (Kx and Kz) and advection velocities (Vx and Vz) based on the 2D advection-diffusion model. Additionally, the apparent residence ages and SGD flux were quantified based on the (224)Ra and (223)Ra activities. The results showed that the Ra activities exponentially decreased with the distance offshore, and both the Kx and Vx took the order of northern part > southern part > middle part. In vertical direction, there was the maximum value of Vz and minimum Kz in middle part and the maximum Kz and minimum Vz 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 (224)Ra was 0.09, 0.01 and 0.03 m d(-1) in the northern, middle and southern parts, respectively. The SGD flux yielded by (223)Ra was 0.08, 0.01 and 0.03 m d(-1) in northern, middle and southern parts, respectively. The result indicates that there is the fastest exchange rate and the biggest SGD flux in the southern part in Bo Sea embayment.
海底地下水排泄（SGD）如今被视为陆地与海洋之间的一条重要通道。在本研究中，为了分析渤海湾天然存在的短寿命镭同位素分布及相对SGD效应，使用镭延迟符合计数（RaDeCC）系统对湾内三个区域的²²³Ra和²²⁴Ra进行了测量。随后，基于二维平流扩散模型，通过计算扩散系数（Kx和Kz）和平流速度（Vx和Vz）来研究混合过程。此外，根据²²⁴Ra和²²³Ra活度对表观停留年龄和SGD通量进行了量化。结果表明，镭活度随离岸距离呈指数下降，且Kx和Vx均为北部＞南部＞中部。在垂直方向上，中部Vz有最大值、Kz有最小值，南部Kz有最大值、Vz有最小值。北部、中部和南部的平均年龄分别为4.28天、7.38天和3.73天。由²²⁴Ra得出的最终SGD通量在北部、中部和南部分别为0.09、0.01和0.03 m d⁻¹。由²²³Ra得出的SGD通量在北部、中部和南部分别为0.08、0.01和0.03 m d⁻¹。结果表明，渤海湾南部的交换速率最快且SGD通量最大。
