Ecological and potential health risk assessment of heavy metals in soils and food crops grown in abandoned urban open waste dumpsite.

PURPOSE

This work investigated the levels, ecological and potential human health risk of heavy metals in soils and crop plants of an abandoned open municipal solid waste dumpsite being used for agricultural crop planting at Ugwuaji in Enugu, Nigeria.

METHOD

Samples of soils and plants were collected from the site and heavy metals (Pb, Cr, Cd, Zn, Al and Fe) contents and some soil physicochemical parameters were determined after wet digestion with Nitric acid/perchloric acid mixture. The digested samples and all the supernatants were analyzed for heavy metals using Atomic Absorption Spectrophotometer (Shimadzu AA7000 made in Japan) fitted with deuterium lamp for background correction.

RESULTS

The heavy metal concentrations in the soils (mg/kg) ranged from 20.825 to 62.501; 7.25 to 11.806; 54.074 to 275.559; 10.861 to 40.139; 1835.751 to 2225.768; and 7166.724 to 11,601.940 for Pb, Cd, Cr, Fe, Al and Zn respectively. The Cr, Fe, Al, and Zn contents (mg/kg) in the plants samples were within the recommended limits but Cd levels were higher.

CONCLUSION

The ecological and health risk assessments revealed contamination and high human health risk associated to Cd. Apart from Cd, other heavy metals under investigation in the soil posed low ecological risk. The target hazard quotient (THQ) values for Cd in the plants samples were all above one except for for , indicating that people consuming the plants cultivated in the vicinity of the dumpsite may experience adverse effects due to Cd toxicity.