Konzentration und Speziation von verschmutzungsrelevanten Spurenmetallen in tropischen, huminstoffreichen Fluss- und Küstensystemen Ost-Sumatras.

In this thesis, the concentrations, distributions, and behaviours of six typically anthropogenic trace metals (Cd, Co, Cu, Fe, Ni, Pb) and dissolved organic carbon (DOC; < 0.45 µm) were determined in humic-rich river systems on Sumatra. This study has been carried out in six rivers and their adjacent estuaries (Rokan, Siak, Kampar, Indragiri, Batang Hari, Musi) on the west side as well as in three humic-poor river systems on the east side of Sumatra. The samples were separated into the dissolved (< 0.45 µm) and the particulate (> 0.45 µm; SPM) phase by conventional filtration. Subsequently, the dissolved phase has been separated into three colloidal fractions (0.45µm - 30 kDa, 30 kDa 10 kDa, 10 kDa - 5 kDa) and into the truly dissolved phase (< 5 kDa) by ultrafiltration. While a generally conservative behaviour of the particulate trace metals in the mixing zones was observed, the dissolved trace metals are partly removed by flocculation of the colloidal fractions, as well as by sorption of the colloidal fractions and the truly dissolved phase to the SPM. Exchange of dissolved trace metals between the colloidal fractions and the truly dissolved phase was observed in all estuarine mixing zones, which is generated by aggregation and degradation of colloidal material. In contrast to the rivers on the east side, the rivers on the west side of Sumatra are characterised by rocky catchments and low concentrations of humic substances implying that the dissolved trace metals are found in the colloidal fractions to a minor extent.