Concentrations of ²³⁸U, ²³⁴U, ²²⁶Ra, ²¹⁰Pb, and ²¹⁰Po in seawater at Thanh Hoa coastal area, Vietnam

Thanh Hoa Coastal was known for many titanium placers and key economic of the estuary area. ²³⁸U, ²³⁴U, ²²⁶Ra, ²¹⁰Pb, and ²¹⁰Po average activities in different sampling stations and depths of seawater at this coast showed 0.77, 0.78, 9.09, 49.8, and 54.3 mBq L⁻¹, respectively. The result showed disequilibrium between ²¹⁰Po and ²¹⁰Pb and different ²¹⁰Po/²¹⁰Pb ratios by depth. The high ²²⁶Ra, ²³⁴U, and ²³⁸U activities could relate to titanium placers along coastal and river sediment sources. There was a relation between ²²⁶Ra and ²¹⁰Pb activities with sampling depth, distance from shore, while it was insignificantly recorded for ²¹⁰Po, ²³⁴U, and ²³⁸U.