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(46-31) Toxicity and trace metal concentrations of sediments from Lake Maryut (Alexandria, Egypt). Prenner, Monika*,1, Ibrahim, Hesham2, Lewis, John1, Crane, Mark1, 1 School of Biological Sciences, Royal Holloway, University of London, Egham, UK2 IGSR, University of Alexandria, Alexandria, Egypt ABSTRACT- Chironomus riparius bioassays and chemical analyses were used to identify areas of high and low sediment pollution in lake Maryut, Egypt so that remediation measures could be targeted. Lake Maryut, which is one of four Nile delta lakes, is situated south of Alexandria. The lake is heavily polluted from industrial, agricultural and domestic effluent sources. In this study 11 sediment samples were collected along two transects in the main basin. Spot samples were taken from adjoining basins. First instar C. riparius larvae were exposed to sediment samples for 10 days, and mortality, weight, and AChE activity of recovered C. riparius larvae were measured. ICP-AES was used to determine trace metal concentrations in each sample. No chironomid larvae survived in samples taken along the northern shoreline of Lake Maryut, where a high number of effluent inputs occur. In contrast, larvae survived after 10 days of exposure to sediment samples from the southern shoreline transect, where there are fewer effluent inputs. However, these surviving larvae showed a reduction in weight and reduced AChE activity compared to larvae from controls. Principal Components Analysis of trace metal concentrations showed a clear distinction between the north and south transect and the neighbouring basins. However, larvae seemed to be more affected by unmeasured components (e.g. organic chemical contaminants) than by metal concentrations. Remediation should focus initially on the northern shore of the lake, but further analyses are necessary to identify a full range of potential organic and inorganic pollutants. Key words: Lake Maryut, Chironomus riparius , bioassay, pollution |
