Interfacial geochemistry of barium in suspension and sediment from Zhujiang Estuary

Chemical forms of Ba are determined in samples of suspension and sediment from the Zhujiang Estuary.Their interfacial geochemical processes are discussed.Total suspended Ba content is between 2.4 and 40.4 μg/L,and mostly exists in the crystalline form (43.5%),secondly in the Fe-Mn oxidative form (23.1%).Percentages of organic,carbonate and exchangeable forms are 14.8%,11.l% and 7.4%,respectively.Total content of Ba in the sediment is between 158.6 and 48.0 ug/g.Percentages of crystalline form,Fe-Mn oxidative form and carbonate form are 78.4%,13.5% and 8.2%,respectively.Organic and exchangeable forms are not detected.The study on the mechanism of interfacial movement suggests that the salinity range of 10 is the turning point for the varied distribution of Ba.The subsidence of crystalline form affects the decrease of Ba content in suspension.The decrease mostly takes place in the salinity range lower than 10,which corresponds to the high value of Ba content in the sediment.