Heavy metal distribution and enrichment at Port-Reitz Creek, Mombasa
Port-Reitz Creek (04°04' S, 39° 39' E) is one of the two main tidal mangrove fringed creeks found in Mombasa Island. It experiences semi-diurnal pattern of two low and two high tides every 24 hour cycle. Six stations were strategically positioned along the length of the creek and sampled for heavy metal (cadmium, copper, iron and zinc) content during July 1998. A peak of Cu and Zn (87 and 235 µg/g dry weight respectively) was observed at Station 2, which borders a steel factory and fish-processing firm. A correlation matrix showed close distribution pattern between Zn and Cu (r = 0.67) and between Fe and Cd (r = 0.62). A peak for Cd (6 µg/g dry wt) was observed at Station 3. Fluvial input in the creek was a source of Cd, Cu, Fe and Zn. Cd and Zn were of anthropogenic origin (Enrichment factor, EF > 1) while Cu seemed to be depleted (EF < 1). Lateral distribution of Cd, Cu, Fe and Zn on surface sediments showed a decline in concentration in a seaward direction.