Coastal Dump Sites in the Lagos lagoon and toxicity of their leachate on brackish water shrimp (Palaemonetes africanus)

Abstract

An assessment of the coastal dumpsites and their impacts on shrimp mortality in the Lagos lagoon was investigated. The study involved a census of dumpsites in the major sections of the coastline associated with anthropogenic activities, followed by specific bioassay to determine the acute toxicity of leachates from one of the dump sites. Our investigations revealed that there were 8 major dumping localities with approximately 28 dumpsites generated mostly by deliberate efforts and in some cases by tidal activities which litter the coastline. The major dumping localities were Abule Eledu, Ebute Ilaje, Oworonshoki, Ibese, Offin, Off Ozumba Mbadiwe Road, Iddo and Okobaba. The largest number of dumpsites was recorded at Owonronshoki and Ibeshe, each with 19% of the total dumps while the least number was recorded at Off Ozumba Mbadiwe Road (4%). The major waste categories include fabrics (worn clothes), plastics, wood and wood shavings, glass, metallic objects as well as paper and packaging materials. The acute toxicity assessment of leachates from a dumpsite at Abule Eledu indicated moderate toxicity to brackish water shrimps (Palaemonetes africanus) with 96 hr LC50 value of 93.59% (935.9ml/L). The leachate was found to be high on biological and chemical oxygen demand, conductivity, total dissolved solids, nitrate and sulphate. The findings from this study indicate widespread and unregulated practice of coastal solid waste dumping with potential effects on water quality and biota. The need for improved waste management system in the City of Lagos was discussed.

Keywords: Aquatic Pollution; Waste Management; Environmental Policy; Solid Waste; Waste Recycling