Fate and spatial distribution of Pb, Cd, Cu and Zn in the water column and in the surface sediment of Indonesian Estuary (Citarum River Estuary)

Abstract

The Citarum River Estuary is an area where mixing among seawater and freshwater occurs since directly connected with the Java Sea. The different condition in estuary will affect heavy metal concentrations in the dissolved phase and suspended/deposited in sediment phase. In this study, fates and distributions from Pb, Cd, Cu and Zn were analyzed along 2 km from estuary mouth. Samples were analyzed by Flame AAS. The study began with water/sediment quality assessments, and fate and distribution analyses with Adsorption Capacity Indices (ACI), Dissolved Transport Indice (DTI), Koc, Kow, spatial distribution in water (3D) and sediment (2D) using MATLAB, and statistical analysis (ANOVA/Kruskal-Wallis). In conclusion, heavy metals sequence from the highest pollution level in water were: Zn > Pb > Cu > Cd, and in sediment were: Cd > Pb > Zn > Cu. Pb, Cd, Cu, and Zn had a tendency to be in sediment compared to water (ACI = 99.69% – 99.89%; DTI = 0.109% – 0.309%), slightly mobile (log Koc = 3.11 – 3.58), and hydrophobic (log Kow = 3.35 – 3.87). Pb and Cd showed significantly different concentrations in water columns (surface/midst/base) (p<0.05), in contrast to Cu and Zn. Pb, Cd, Cu, and Zn had insignificant concentration difference based on zone division from estuary mouth, both in water and sediment.