Lead-210 and polonium-210 in the winter well-mixed turbid waters in the mouth of the Yellow Sea

Concentration profiles of ²¹⁰Pb and ²¹⁰Po were measured along a traverse of the mouth of the Yellow Sea in February 1993. Winter time suspended particulate matter concentration was more than 10-100 mg l^-1 in the coastal domain and less than 10 mg l^-1 in the central domain. Concentrations of dissolved ²¹⁰Pb over the area were low (< 5 dpm kg^-1) due to the efficient removal of ²¹⁰Pb from the water column over the shelf. Evidence for release of ²¹⁰Po is seen in a sub-surface layer, close to the sediment-water interface, where ²¹⁰Po is enriched in the dissolved form and depleted in the particles. The high concentration of SPM in the mouth of the Yellow Sea appears to determine dissolved and particulate ²¹⁰Pb and ²¹⁰Po activities. The atmospheric input of ²¹⁰Pb is the major source of ²¹⁰Pb in the region with minor contribution from the ²¹⁰Pb rich Kuroshio Water. The K(d) values of ²¹⁰Po varied by a factor of 50 while the corresponding values of ²¹⁰Pb varied only by a factor of 4. It appears that in waters where particle concentrations are high (> 10 mg l^-1), the K(d) appears to be independent of particle concentration.