TITLE:
Evaluation of Agricultural Contamination Level by Heavy Metals and Pesticides in Sediments of Rivers and Water Bodies for Shrimp Fishing in the Lower Ouémé: Case of the Aguigadji, Ahlan and Sele Stations in Benin
AUTHORS:
Souradjou Orou Goura, Fadéby Modeste Gouissi, Armelle Sabine Yélignan Hounkpatin, Wakili Bolatito Yessoufou, Tayéwo Sylvain Biaou, Nonvignon Martial Fassinou
KEYWORDS:
Pesticides, Heavy Metals, Sediments, Shrimp Fishing Area, Lower Ouémé
JOURNAL NAME:
Advances in Materials Physics and Chemistry,
Vol.14 No.2,
February
5,
2024
ABSTRACT: This study assessed sediment contamination by heavy
metals and pesticide active ingredients linked to chemical inputs used in
agricultural activities in the lower Ouémé. Pesticide residues from the
organochlorine, pyrethroid and organophosphorus families were investigated by
gas chromatography, and heavy metals (Cd, Pb, As, Ni, Zn, Fe, Mg, Cr and Hg) by
atomic absorption spectrophotometry. The metallic pollution indices, the
contamination factor (CF) and the ecological risk index were calculated. The
results revealed 8 active ingredients in the rainy season and 9 in the dry
season. Glyphosate was the active ingredient with the highest concentration at
all stations, 9.65 ± 0.84 mg/kg recorded in the dry season at the Aguigadji
station. All glyphosate values were above the EQS. DDT, Atrazine and Endosulfan
also showed high concentrations in the dry and rainy seasons. Emamectin,
Abamectin and Lambda Cyhalothrin also showed high concentrations in the dry
season at Aguigadji, Ahlan and Sele. Only glyphosate was recorded at the
control station (Toho), but in very low concentrations. Lead showed the highest
concentrations at all the stations, 265.96 ± 21.02 mg/Kg in the rainy season
and 255.38 ± 79.09 mg/Kg in the dry season, all detected at the Aguigadji
station and above the EQS. Zn, Ni, Fe, Cu and Cr were all representative in
both the dry and rainy seasons at the contaminated stations. Manganese showed
high concentrations in the rainy season. Pb showed very high contamination (FC
≥ 6) at the Aguigadji and Ahlan stations and significant contamination (3 ≤ FC 6) at the Sele station in both the rainy and dry seasons. Ni, Hg and Cd,
showed either moderate or significant contamination at the contaminated
stations. The risk values showed a considerable ecological Ri (190 ≤ Ri