The Impact of Agrochemicals on Heavy Metal Concentrations in Agricultural Soil

Abstract

Concentration of six heavy metals (Cu, Cr, Ni, Cd, Zn and Pb) were studied in the soils around Fadama area in Argungu Local Community, Kebbi State, Nigeria to assess heavy metals contamination distribution due to agricultural activities. Soil samples were collected at a depth of 0-15 cm in Fadama agricultural areas and the Fallow ground. The soil samples randomly obtained were subjected to wet digestion and the concentration of total metal was determined using the convectional Atomic Emission Spectroscopy (AES). Overall concentrations of Cd, Cr, Ni, Pb, Cu and Zn in the soil samples ranged from 0.01-0.06, 0.03-3.11, 0.69-2.40, 0.29-3.33,0.65-7.02 and 0.95-22.61 mg/kg respectively. The concentration of heavy metals in the soil display the following decreasing trend: Zn>Cu>Pb>Cr>Ni>Cd. The Pollution index revealed that Cu and Pb were classes as heavily contaminated in the Fadama areas, 23% of the samples in the Fadama areas are moderately contaminated, while 66% of the samples showed low contamination. Conversely, 100% of the samples collected from the fallow ground showed low contamination levels. Results of combined heavy metal concentration and heavy metal assessment indicated higher metals concentration in the Fadama areas, that could be as a consequence of agricultural activities. Indiscriminate used of agrochemicals in agricultural activities could have negative impacts on the environment, especially pollution loadings which can cause adverse effects in the food chain, natural ecosystems and decreased biodiversity. These indicate that heavy metal contamination especially Cu and Pb, should be taken into account during development strategies to protect the Fadama areas from long term pollution load