Contamination Characteristics, Source Analysis and Health Risk Assessment of Heavy Metals in Some Aquatic Insects Found in River Gashua, Yobe State Nigeria

Abstract

The study assesses the level of heavy metals in some aquatic insects, lethocerus species, and Hydrophilus piceus (Great silver water beetles) found in river Gashua.  The insects and soil samples found in the river were randomly collected, processed, and analysed for heavy metals using atomic absorption spectrophotometry (AAS).  There’s no significant difference in the soil samples and the aquatic insects: Lethocerus species and Hydrophilus picueus.  The results also showed that the range of the concentrations of heavy metals found in the three samples in the order of their abundance as Mn > Pb > Cu > Ni > Cd and 0.03-1.71mg/kg  > 0.03-1.15mg/kg  > 0.05-0.54 mg/kg >  0.05-0.28 mg/kg  > 0.05-0.28 mg/kg respectively.  The results were compared to acceptable levels set by the FAO/WHO to see if the heavy metal levels in the insects were safe.  Assessment of the heavy metals in the soil and aquatic insects gives an idea of how heavy metals are transferred within a food chain and shows the level of bioaccumulation of the metals in aquatic insects.  The implications of the selected heavy metals found in the area's soil and aquatic insects were identified and discussed.  Practices that will reduce heavy metal pollution rates are encouraged among the inhabitants.  It was recommended that assessing the heavy metals concentration in the soil and the aquatic insects should be a routine to prevent excessive accrual in the food chain.