EVALUATING THE ROLE OF LOCATION-BASED POLLUTION IN HEAVY METAL CONTAMINATION OF VEGETABLES GROWN IN BENIN METROPOLIS.
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Abstract
Urban vegetable cultivation in Benin Metropolis contributes significantly to household nutrition but faces contamination risks from heavy metals. This study assessed heavy metal concentrations in vegetables grown in polluted areas (Ibiwe axis) and less contaminated zones (Oko community). A comparative cross-sectional design was adopted, and samples of Talinum triangulare (water leaf), Ocimum gratissimum (scent leaf), Vernonia amygdalina (bitter leaf) and
Telfairia occidentalis (pumpkin leaf) were collected from dumpsites, mechanic workshops and residential gardens. Following acid digestion, cadmium (Cd), lead (Pb), nickel (Ni), copper (Cu) and zinc (Zn) levels were determined using Atomic Absorption Spectrophotometry. Independent sample t-tests (p < 0.05) showed significantly higher concentrations of Cd, Zn and Ni in vegetables from polluted sites. For instance, Cd in water leaf was 0.017 ± 0.001 mg/kg in
polluted sites compared with 0.004 ± 0.001 mg/kg in cleaner areas, while Zn in scent leaf reached 0.080 ± 0.001 mg/kg against 0.002 ± 0.001 mg/kg. Bitter leaf showed the highest accumulation across all metals, particularly Ni (p = 0.001). Although overall concentrations were below WHO/FAO limits, polluted-site vegetables contained 4–40 times more metals than those from unpolluted zones. These findings highlight that cultivation location strongly influences
metal accumulation and emphasize the need for stricter environmental controls and regular
monitoring to safeguard public health.
Telfairia occidentalis (pumpkin leaf) were collected from dumpsites, mechanic workshops and residential gardens. Following acid digestion, cadmium (Cd), lead (Pb), nickel (Ni), copper (Cu) and zinc (Zn) levels were determined using Atomic Absorption Spectrophotometry. Independent sample t-tests (p < 0.05) showed significantly higher concentrations of Cd, Zn and Ni in vegetables from polluted sites. For instance, Cd in water leaf was 0.017 ± 0.001 mg/kg in
polluted sites compared with 0.004 ± 0.001 mg/kg in cleaner areas, while Zn in scent leaf reached 0.080 ± 0.001 mg/kg against 0.002 ± 0.001 mg/kg. Bitter leaf showed the highest accumulation across all metals, particularly Ni (p = 0.001). Although overall concentrations were below WHO/FAO limits, polluted-site vegetables contained 4–40 times more metals than those from unpolluted zones. These findings highlight that cultivation location strongly influences
metal accumulation and emphasize the need for stricter environmental controls and regular
monitoring to safeguard public health.
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