TITLE:
Mercury Concentration Profile in Sediment Cores of a Tropical Lagoon under High Anthropogenic Activities around an Urban City—Abidjan, Côte d’Ivoire
AUTHORS:
Achille Gueu, Sébastien Koffi Ouffoué, Bruno Zeli Digbéhi
KEYWORDS:
DMA-80, Mercury, Pollution, Sediments
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.9 No.5,
May
28,
2021
ABSTRACT: The
present study focuses on the quantification of mercury in sediment cores from
Cocody, Banco, Koumassi and Milliardaires bays in Abidjan, Côte d’Ivoire. It
aims at assessing the state of mercury contamination of the lagoon bottom using
DMA-80 (Direct Mercury Analyser). The automatic analyzer DMA-80 mercury is an
innovative instrument for the analysis of mercury at very low content in solid
and liquid samples in five minutes, without requiring any prior steps of
pretreatment wet. The results showed, according to the lithological description
of different bays, that the cored sediments consist of mud, sand, sandy mud or
muddy sand with occasional shells. In addition, our results showed the presence
of mercury in the sediments of the lagoon bottom at a degree of contamination
that varies from moderate to very high according to the calculated
contamination factor (CF) values. The highest contamination was observed in
Cocody Bay at the surface with a contamination factor of 7.5, while the lowest
contamination was observed in Milliardaires Bay at the water-sediment interface
with a contamination factor of 1.67. In addition, mercury concentrations
compared to sediment guide values (SQGs) reveal that these sediments mostly
show occasional biological effects but no toxicity except Koumassi core
(sediments at 20 cm depth). Also, dredging, hydrodynamics have probably
impacted the mercury content. The depositional environment of mercury metal is
therefore a limiting factor for its fate in the aquatic environment.