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. 238 U, 234 U, 226 Ra, 210 Pb, and 210 Po 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 210 Po and 210 Pb and different 210 Po/ 210 Pb ratios by depth. The high 226 Ra, 234 U, and 238 U activities could relate to titanium placers along coastal and river sediment sources. There was a relation between 226 Ra and 210 Pb activities with sampling depth, distance from shore, while it was insignificantly recorded for 210 Po, 234 U, and 238 U.