Abstract：
A prototype tool has been developed for deriving sediment distribution coefficients,Kd, in the marine environment by harvesting simultaneous measurements of activity concentrations of radionuclides in seawater and sediments based on the International Atomic Energy Agency\'s Marine Radioactivity Information System (MARIS). As a case study, theKdvariability in the Baltic Sea was investigated as this region has been extensively monitored by HELCOM since 1984 resulting in a comprehensive dataset with good spatial and temporal coverage and required ancillary parameters. The prototype tool was used to derive a dataset ofin-situapparentKd(a)values derived from measurements of seawater and sediment in quasi-equilibrium conditions from the Baltic Sea over a period of approximately 35 years. For Cs, a comprehensive analysis of the Baltic SeaKd(a)dataset was undertaken, focusing on the temporal trend ofKd(a)and comparing the results toKdvalues derived elsewhere. For Sr and Pu, for which there were fewer data records available a more rudimentary analysis was carried out. The CsKd(a)median values derived from137Cs data in this study were estimated to be 2154 l kg-1for seabed sediment and 10 000 l kg-1for suspended sediment. The value derived for seabed sediment is in good agreement with the previously recommended ocean margin CsKdvalue of 4000 l kg-1. The analysis demonstrated the important distinction in the Baltic Sea betweenKdvalues for seabed sediment and suspended sediments, which differed by an order of magnitude. The analysis also highlighted the dependence ofKdvalues on the variation in both the salinity of seawater and the type of seabed sediment. Such variability can significantly influence outcomes when modelling the behaviour of radionuclides in marine dispersion modelling.
摘要：
已开发出一种原型工具，用于推导沉积物分布系数，Kd,在海洋环境中，通过基于国际原子能机构的海洋放射性信息系统（MARIS）同时测量海水和沉积物中放射性核素的活度浓度。作为一个案例研究，研究了波罗的海的Kdvariability，因为自1984年以来，HELCOM对该地区进行了广泛的监测，从而形成了具有良好时空覆盖和所需辅助参数的综合数据集。原型工具用于得出现场Kd（a）值的数据集，该数据集是在大约35年的时间内从波罗的海准平衡条件下对海水和沉积物的测量得出的。对于Cs，对波罗的海Kd(a)数据集进行了全面分析，关注Kd(a)的时间趋势，并将结果与其他地方得出的Kd值进行比较。对于Sr和Pu，对于可用的数据记录较少，进行了更基本的分析。在这项研究中，从137Cs数据得出的CsKd（a）中值估计为海底沉积物为2154lkg-1，悬浮沉积物为10000lkg-1。得出的海底沉积物值与先前建议的海洋边缘CsKd值为4000lkg-1非常吻合。分析表明，波罗的海海底沉积物和悬浮沉积物的Kd值之间存在重要区别，相差一个数量级。分析还强调了Kd值对海水盐度和海底沉积物类型变化的依赖性。在对海洋弥散建模中的放射性核素的行为进行建模时，这种可变性会极大地影响结果。
