| Abstract: | The distribution and nature of the As-bearing components of the sediments of selected fresh water lakes in Saskatchewan, Canada, were studied. The total As contents ranged from 2.7 to 13.2 ppm As and were found to be present in both colloidal and non-colloidal fractions of the lake sediments. The proportion of the As bound to carbonates, organic matter and sesquioxides accounted for 12 to 74% of the total As of the sediments. The remaining As was apparently associated with apatite and silicates. The data indicate that the bulk of As in the lake sediments resides in sesquioxidic components and apatite. The release of As from the lake sediments would thus be affected by the stability of these As-bearing components in a series of particle size fractions. Furthermore, based on information on the geographical distribution of As in the lake sediments, land erosion and agricultural runoff appear to be contributing significantly to the As concentration in lake sediments. It is thus suggested that close attention should be paid to land management and soil conservation to prevent further enrichment of As in lake sediments and to curtail the subsequent As contamination of the food chain. |
