The study evaluated the levels of some heavy metals in the roadside soils at different traffic circles using geo-accumulation index, ecological risk and Hakanson method to assess the overall ecological risk and identify ecological potential risk of heavy metals pollution. The top soil samples were collected at three different traffic circles from edge and at 50 m distance from the roadside, and analysed for heavy metal (Pb, Cd, Cu and Zn) using atomic absorption spectrophotometer. The mean concentrations of heavy metals (mg/kg) ranged from (15.0-45.07) Pb, (0.35-2.60) Cd, (19.05-38.0) Cu and (58.10-101.0) Zn. The abundance of metals was found in declining order: Zn > Pb > Cu > Cd. The metals concentrations were found to be higher in the soil samples from edge due to high traffic volume and human activities, and there was significantly decrease in concentration with increase in roadside distance. The Geoaccumulation index (Igeo) examined in this study revealed that soil samples from edge and 50 m distance from the roadside were polluted with cadmium. Ecological risk assessment carried out showed that the metals posed low ecological risk and cadmium contributed 66.63-94.21% of the total potentially ecological risk.

The concentrations of potentially toxic elements (Fe, Cd, Pb, Cu, Ni, Cr, and Zn) in most consumed medicinal herbs in Northern Nigeria were analyzed using Atomic Absorption Spectrometry (AAS). Twenty medicinal herbs were selected and purchased from the local markets. The findings of the study revealed that the investigated herb samples contained considerable levels of elements; Cu, Fe, Pb, Cd, and Cr above the permissible limits. The health risk observed as hazard index (HI) indicated that values were >1, in some samples. Therefore, the consumption of these studied medicinal herbs should be monitored to prevent the health implication due to a high level of these elements in the medicinal herbs.

The potential of Lonchocarpus laxiflorus roots (LLR) for the removal of Cd (II) ions from aqueous solutions has been investigated. The adsorption of Cd (II) ions was found to be affected by solution pH, contact time, adsorbent dosage, initial metal ion concentration, and temperature. The equilibrium was analysed using Langmuir and Freundlich isotherm models. The data was found to have a closer correlation with the Lamgmur isotherm as evidenced by a higher correlation coefficient (R 2). The adsorption capacity for L. laxiflorus was found to be 19.35 mg g-1 and the removal efficiency of the LLR was found to be 98% under optimized conditions. The kinetics data was also subjected to pseudo-firstorder and the pseudo-second-order kinetic models. The data could be explained better using the pseudo-second-order kinetic model. The selected biosorbent has been analyzed by FT-IR for identification of contributing functional groups, x-ray powder diffraction (XRD) for its structural properties and scanning electron microscope (SEM) for the structural morphology analysis.

This study determined the levels of three different sites within Gombe metropolis. at each sampling site using standard method. metals (As, Cr and Ni) using Atomic Absorption Spectrophotometer. The concentration of heavy metals ranged from 0.96-1.95 mg/kg for Cr, and 1.06-2.11 mg/kg at A site, 0.98 while the concentration of As was below detectable limit in all the study sites. The mean concentrations of the metals were compared with that of Department of Petroleum Resources (DPR, 2002) Standard values for Nigerian All the concentration of the metals studied were found to be below the DPR and WHO target values. Results of contamination factor (Cf) showed contaminated one with Cr and Ni being found with values greater than one. The values of Pollution Load Index obtained from these three sites (PLI <1) were less than 1 in all the studied sites, thus indicating perfection.

The concentration of DDT and its metabolites in the two fish species (Clarias gariepinus and Bagrus docmak) from River Gongola basin and its dam, Dadinkowa in Gombe State Nigeria was determined and human health risk association from the consumption of contaminated fish was evaluated. Fish samples were collected for period of six months and the pesticide residues analysis was carried out by using QuEChERS method along with conventional method (Hand shaken technique) and gas chromatography with electron capture detector (GC-ECD). (DDTs) and its metabolites were observed with DDD were the predominant contaminants, followed by DDT. The predominance of DDE may be attributed to their current use in vector control and contamination from past usage. The estimated daily intakes (EDIs) of DDT and its metabolites from all fish species were much lower than the acceptable daily intakes (ADIs), indicating that consumption of fish is at little risk to human health at present. However, the cancer risk estimates in the area of concern and the hazard ratios (HRs) of DDTs below the threshold value of one, indicating daily exposure to these compounds is a potential concern.