Abstract

A natural, riparian buffer/farm adjoining a 3000 m² suburban animal park/market in Uyo municipality was investigated to establish the heavy metal (HM) pollution and transfer to plants/vegetables grown on the soil affected by polluted runoff and organic waste disposal from upslope animal market/park. Wet acid digestion and atomic absorption spectrometry were applied to determine HM concentrations.  Data were analyzed using SPSS ver.17. Heavy metal pollution index (HPI), transfer factor (TF) and leaf/root HM ratio (LFR) were evaluated. Heavy metal concentrations in the contaminated soils were high and significantly above normal ranges (p<0.05; p<0.01). The HM concentrations varied significantly (p<0.05) between plots on the buffer/farm. Significant correlation (r = 0.862-0.968, p< 0.01) between HM in contaminated farm soil and cultivated plants was observed. HPI varied between 1.84 and 1.80. TF showed wide variability between farm plots and metal analytes. The HM levels in vegetable leaves were high and correlated significantly with HM in its soil (r = 0.874) and in roots (r = 0.986). HM leaf/root ratio >1.0 was obtained for 6 HMs, while Cd, Hg and V had <1.0. Regulating the content of Pb in soil can control the level of co-absorption of other HMs by plants.

Key words: Heavy metal toxicity, riparian farmland, sub-urban animal market, vegetables, heavy metal pollution index (HPI), transfer factor.