Document Detail

Fractionation and ecotoxicological implication of potentially toxic metals in sediments of three urban rivers and the Lagos Lagoon, Nigeria, West Africa.
MedLine Citation:
PMID:  25069633     Owner:  NLM     Status:  Publisher    
The potential environmental impact of sediment-bound Cd, Cr, Cu, Pb and Zn in three trans-urban rivers in Lagos state and in the Lagos Lagoon was assessed by use of the modified Community Bureau of Reference (BCR) sequential extraction. The quality of the data was checked using BCR CRM 143R and BCR CRM 701. Good agreement was obtained between found and certified/indicative values. Of the rivers, the Odo-Iyaalaro, was generally the most contaminated and the Ibeshe the least. Higher concentrations of metals were generally found in the dry season compared to the wet season. Cadmium and Zn were released mostly in the acid exchangeable step of the sequential extraction, indicating that they have the greatest potential mobility and bioavailability of the analytes studied. Chromium and Cu were associated mainly with the reducible and oxidisable fractions, and Pb predominantly with the reducible and residual fractions. Sediments with the highest pseudototal analyte concentrations also released higher proportions of analytes earlier in the sequential extraction procedure. The study suggests that, during the dry season, potentially toxic metals (PTM) may accumulate in sediments in relatively labile forms that are released and can potentially be transported or bioaccumulate in the rainy season. Application of risk assessment codes and Hankanson potential risk indices indicated that Cd was the element of greatest concern in the Lagos Lagoon system. The study indicated that there is a need to strengthen environmental management and pollution control measures to reduce risk from PTM, but that even relatively simple strategies, such as seasonal restrictions on dredging and fishing, could be beneficial.
Aderonke O Oyeyiola; Christine M Davidson; Kehinde O Olayinka; Babajide I Alo
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2014-7-29
Journal Detail:
Title:  Environmental monitoring and assessment     Volume:  -     ISSN:  1573-2959     ISO Abbreviation:  Environ Monit Assess     Publication Date:  2014 Jul 
Date Detail:
Created Date:  2014-7-29     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8508350     Medline TA:  Environ Monit Assess     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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