Toxicity assessment of African locust bean effluents on agricultural soil and aquatic organism at Jimba- Oja and Temidire locust bean ( Parkia biglobosa) processing centers

Abstract

Indiscriminate processing of agricultural produces has led to the alteration of agricultural soil and aquatic habitat, consequently threatening food security, human health and natural population size of aquatic organisms. This study investigated chemical properties of the soil at Jimba- Oja and Temidire locust bean (Parkia biglobosa) processing centres. The static bioassays were also performed on Clarias gariepinus to evaluate the median lethal concentrations of the locust bean effluents within 72 and 96 hours. Physico-chemical parameters of effluents showed that pH was slightly acidic (6.44 to 6.73 respectively). The dissolved oxygen ranged from 6.48 to 6.73 mg/L and phosphate from 67.52 to 82.60 mg/L. The concentration of copper, iron, nickel ranged from 6.77 to 8.84, 32.57 to 47.67 and 0.21 to 1.04 mg/L respectively. These parameters exceeded the Federal  Environmental Protection Agency (FEPA) permissible limits. The Effluents from Parkia biglobosa impacted soil with high concentrations of heavy metals ranging from: copper 4.72 to 5.02, cadmium 0.03 to 0.35, iron 51.82 to 76.41 and nickel 0.13 to 0.05 at processing centers compared to the control site. Toxicity assessments indicated that the mortality increased with increase in effluent concentration. LC tests (36 %:72 hours), (20 %: 96  hours), (30.1 %: 50 72 hours) and (20 %: 96 hours) concentrations were carried out for Jimba-oja and Temidire respectively and the sublethal dose of below 7.5 % for both Parkia biglobosa processing centers were obtained. The study concluded that releasing Parkia biglobosa effluent to the  environment have negative impacts on agricultural soil and aquatic organisms. There is therefore need for relevant government agencies to control indiscriminate discharge of these effluents into the environment untreated. Keywords: Locust bean effluent, Toxicity, Agric soil, Aquatic Organism