Impact of Agricultural Chemical Inputs on Metal Levels in Soil And Arable Plants on Kwali Area Council

ABSTRACT     

The concentrations of Pb, Cu, Zn, Ni and Cd in agricultural soils and vegetation of Kwali Area Council were determined by flame atomic absorption spectrophotometry. The HN03 -HCI04-HF mixture was used for the digestion of soil samples for metal determination, while HNOTHCI04 was used for metals determination in vegetation. The coefficient of variation for Pb, Cu, Zn, Ni and ....... Cd in soil were 4.0%, 4.8%, 3.2%, 3.9% and 4.3% while in vegetation were 7.0%, 4.8% 5.4%, 6.9% and 7.2% for Pb, Cu, Zn Ni and Cd respectively. Recovery studies carried out for the analysis of metals in soil samples using HN03 -HCI04-HF procedure gave percentage recovery for metals as 96 ±3.8%, 95±1.6%, 96±2.9%, 95±4.3% and 96+1.9% for Pb, Cu, Zn Ni and Cd respectively. The analysis of metals in vegetation samples using HNOT HNCI04 procedure gave percentage recovery as 96±1.5%, 97±1.9%, � 97±1.1 %, 97±1.1% and 98±1.3% for Pb, Cu, Zn, Ni and Cd respectively. The mean concentration (I Jg/g) and ranges of Pb, Cu, Zn, Ni and Cd in agricultural , soils were 8.30±1.70 (5.59 - 11.00), 11.52±2.23 (8.20-15.80), 15.44±2.81 (10.40-20.00), 8.90±1.70 (6.00-12.40(!nd 0.73±0.05 (0.64-0.84) respectively, whilst 1.80±0.50 (1.00-2.50), 2.61 ±0.80 (1.20-4.00), 3.02±0.66 (1.80-4.1 0), 2.1 0±1.1 0 (0.60-4.20) and 0.24±0.07 (0.1 0-0.32) were the mean concentrations ( I Jg/g) and ranges for Pb, Cu, Zn, Ni and Cd respectively in vegetation. A significant correlation was obtained between plant Pb/soil Pb (0.799), plant/soil Cu (0.965) and plant Cd/soil Cd (0.604) at 95% confidence limit. These results suggest that anthropogenic activities such as the use of agricultural materials appear to be the source of these metals in the study area. However, the concentration of metals studied in soil and vegetation were within the acceptable levels