Determination of Heavy Metals in Sawdust Particles, Distribution in Soil and Accumulation in Plants at Ahiaeke Timber Market in Umuahia, Nigeria

Abstract

Farmers are constrained to farming on lands adjoined to sources of pollution without considering the health implications of consuming crops grown on such lands. The main route of entry of heavy metals in human body is via ingestion of food contaminated with heavy metals. Heavy metal toxicity has proven to be a major threat and there are several health risks associated with it. This, therefore, necessitated the determination of heavy metals in sawdust, distribution in soil and accumulation in plants at Ahiaeke timber market in Umuahia, Abia State. The study assessed metals (chromium [Cr], zinc [Zn], cadmium [Cd], and copper [Cu]) in sawdust particles, their distribution in soil and accumulation in plants. The highest concentration of Zn (51.00±1.84 mg/kg) and Cr (0.170±0.014 mg/kg) was observed at the sawdust dump 2, Cu (8.24±0.60 mg/kg) was highest at sawdust dump 1 while Cd (4.72±0.071 mg/kg) was highest at sawdust dump 3. The values of the highest concentration of Zn (119.7±7.02 mg/kg), Cu (75.85±4.80 mg/kg) and Cd (22.39±3.30 mg/kg) in soil were observed in 0-10 cm depth at the distance of 20 m. The values of Zn (119.7±7.02 mg/kg) and Cd (22.39±3.30 mg/kg) in soil is above the maximum permitted levels of 60 mg/kg (Zn) and 0.1 mg/kg (Cd) established by the Codex Alimentarius Commission. The highest concentration of Zn (34.70±7.05 mg/kg), Cu (5.34±0.11 mg/kg) and Cd (2.94±0.515) in plants was assimilated by Centrosema pubescence. The level of Cd in plants is well above the permissible limit (PL) 0.3 mg/kg set by FAO/WHO for vegetables and herbs. Consumption of such contaminated C. pubescence can be a route of entry of Cd in grazing animals’ vis-à-vis the people who depend on such herbivores for protein.