Assessment of Heavy Metals in Cassava Mill Effluents Contaminated Soil in a Rural Community in the Niger Delta Region of Nigeria

This study assessed the level of some selected heavy metals in cassava mill effluents contaminated soil from Ndemili community in the Niger Delta region of Nigeria. Triplicate soil samples were collected using soil augar at 0 20 cm depth from 6 locations including one control. Sampling was carried out bimonthly (from November 2016 to September 2017) covering the two predominant seasons wet and dry. The samples were dried, digested and analyzed using flame atomic absorption spectrophotometer (FAAS). Result for both spatial and bimonthly distribution of heavy metals for copper 1.10 6.83 mg/kg, zinc 14.32 46.15 mg/kg, manganese 18.42 47.49 mg/kg, iron 1303.29 4934.04 mg/kg, lead 1.33 9.42 mg/kg, cadmium < 0.001 0.24 mg/kg, chromium 0.19 3.41 mg/kg, nickel 1.57 3.76 mg/kg and cobalt < 0.008 9.71 mg/kg. Analysis of variance showed that there was significant variation (P < 0.05) among the various locations, months and interaction of locations and months apart from iron and chromium in the bimonthly distribution. Positive significant correlation (P < 0.05) also exists among most of the heavy metals, indicating that contamination is of similar origin apart from cadmium that showed negative correlation with cobalt. The study showed that cassava mill effluents are having impact on soil receiving the effluent with regard to heavy metals concentration.