Levels of natural and anthropogenic radionuclides in selected environmental radioactivity monitoring sites in Singapore

Abstract This paper provides insights into the radioactivity levels in soil, sediment and surface seawater from selected monitoring sites in Singapore. The environmental samples were measured for naturally occurring and anthropogenic radionuclides. In soils, the decay series of ²³²Th and ²³⁸U are the highest contributors to the total radioactivity, while in sediments, ⁴⁰K is the main contributor to the total radioactivity. The levels of ⁹⁰Sr, ¹³⁷Cs and ²³⁹⁺²⁴⁰Pu are also reported. The data demonstrates that the main source of anthropogenic radionuclides in soils is the global fallout from nuclear weapons testings; in sediments, contributions from the Pacific Proving Grounds have been identified. This study also highlights significant differences in radioactivity levels in soils between the northern and central regions of Singapore, which are attributed to the histories of the monitoring sites.