ABSTRACT
Muthurajawela marsh in Sri Lanka is an ecologically and economically significant, unique ecosystem with high biodiversity. Acid sulfate soil (ASS) soil materials in Muthurajawela soil are a good source and sink of trace elements. Previous studies have shown an occurrence of higher amounts of trace elements such as Cu, Zn and Cr in Muthurajawela marsh. However, the occurrence of arsenic (As) and its potential for mobility in soils are unknown. In this study we estimated the arsenic content partitioned into different soil fractions down the soil profiles in three different locations of the marsh. The sulfidic soil material content was also determined as chromium reducible sulfur (CRS) in the same soil profiles. Soils collected from northern and middle segments of the marsh contained substantial amount of As exceeding the natural background level (40 mg As kg-1) set for soils. More than 75% of the total As in these two soil profiles was partitioned into ASS materials (e.g. pyritic or iron oxyhydroxy sulfate minerals) indicating a close relationship between As and ASS materials.
