Uptake of heavy metals by some edible vegetables irrigated using wastewater

a preliminary study in Accra, Ghana

Michael Ackah*, Alfred Kwablah Anim, Eva Tabuaa Gyamfi, Nafisatu Zakaria, John Hanson, Delali Tulasi, Sheriff Enti-Brown, Esther Saah-Nyarko, Nash Owusu Bentil, Juliet Osei

*Corresponding author for this work

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

The heavy metals (Fe, Zn, Pb, Ni, Cr, Co, and Cd) burden in wastewater, soil, and vegetable samples from a wastewater irrigated farm located at KorleBu, Accra has been investigated. Flame atomic absorption spectrometry after microwave digestion using a combination of HNO3, HCl, and H 2O2 (for water), and HNO3 and HCl (for soil and vegetables). The mean concentrations (in milligrams per kilogram) of heavy metals in the soil samples were in the order of Fe (171 ± 5.22) > Zn (36.06 ± 4.54) > Pb (33.35 ± 35.62) > Ni (6.31 ± 8.15) > Cr (3.40 ± 3.63) > Co (1.36 ± 0.31) > Cd (0.43 ± 0.24), while the vegetables were in the order of Fe (183.11 ± 161.2) > Zn (5.38 ± 3.50) > Ni (3.52 ± 1.27) > Pb (2.49 ± 1.81) > Cr (1.46 ± 0.51) > Co (0.66 ± 0.25) > Cd (0.36 ± 0.15). The bioconcentration factors suggest environmental monitoring for the heavy metals as follows: Cd (0.828), Cr (0.431), Ni (0.558), Co (0.485), and Fe (1.067). Estimated daily intakes were very low for both children and adults except Fe (0.767 mg/kg/day) in children. The population that consume vegetables from the study area were, however, estimated to be safe based on the results obtained from the health risk index, which were all < <1. The sodium absorption ratio according to FAO (1985) classifications indicate that the wastewater in the study area is unsuitable for irrigation purposes.

Original languageEnglish
Pages (from-to)621-634
Number of pages14
JournalEnvironmental Monitoring and Assessment
Volume186
Issue number1
DOIs
Publication statusPublished - Jan 2014
Externally publishedYes

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Keywords

  • bioconcentration factor
  • health risk index
  • irrigation
  • monitoring
  • vegetables

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