Sediment accumulation rate and radiological characterisation of the sediment of Palmones River estuary (southern of Spain)

Abstract

Chemical analyses and radioecological methods were combined in order to estimate the sediment accumulation rate in the upper 20 cm depth of the Palmones River estuary. Organic matter, total carbon, C:N and 137Cs vertical profiles showed changes at 13 cm depth. These changes could be associated with the decrease in river input since 1987 when a dam situated in the upper part of the estuary started to store water. Using 1987 as reference to date the sediment, accumulation rate was 1.2 cm yr −1. As alternative method, two layer model of 210Pb xs vertical distribution showed a sedimentation rate of 0.7 cm yr −1 with a surface mixing layer of 7 cm thickness. The high ammonium, potassium and sodium content in pore water and the strong correlation between 137Cs activities and organic matter in dry sediment suggests that 137Cs (the only anthropogenic product detected) is mainly accumulated in the estuary associated with the particulate organic material from the catchment area.