The dating and distribution of 239+240Pu in the sediment cores of the marginal sea of China

Abstract

According to 77 sedimentary cores of 239+240Pu in the marginal sea of China, the distribution and time-scale characteristics of 239+240Pu were analyzed, and 26possible cases of dating with 210Pb, 137Cs, and 239+240Pu were given in theory, which were in good agreement with the actual situation. The overlapping of 239+240Pu sedimentary cores from different sources made the peak profile of 239+240Pu obvious in the coastal waters (especially in estuaries). From near shore to far sea, the distribution of 239+240Pu in sedimentary cores may have bimodal distribution (multi-peaks), unimodal distribution and non-peak distribution due to the influence of comprehensive factors such as 239+240Pu source, seawater depth, Kuroshio current mixing, diffusion effect and boundary clear-up effect. When 239+240Pu in the sedimentary core present a unimodal distribution, it corresponded to the peak year of global fallout in 1963, and the time scale value was reliable. The reliability of 210Pb, 137Cs, and 239+240Pu dating under different marine environment conditions should be analyzed according to the specific marine sedimentary environment because of the difference of sedimentary properties of 137Cs and 239+240Pu.