This study profiled labile exogenous metals ubiquitous in the ecology of Ogun River induced by persistent anthropogenic activities along the riverbanks. The labile metals existing as metal-ions were trapped with a passive sampling technique of diffused gradients in thin films (DGT) subsequent upon which the metal-ions were carefully extracted and analyzed using the Atomic Absorption Spectroscopy (AAS). Nine labile metals (Pb, Cd, Ni, Cr, Co, Cu, Mn, Fe and Zn) were targeted in this study. The results of the study showed that mean values of labile Fe and Zn exceeded 3 µg/L whilst those of labile Pb, Cd and Mn occurred in the range of 1.41 and 1.88 µg/L in the river matrices. The mean values of labile Cr, Co, Ni and Cu occurred below 1.0 µg/L in the river matrices. The high industrial activities and population density along the Isheri, Ilo and Owo axes of the Ogun River accentuated the presence of labile Pb, Zn and Fe in the river matrices.

There is an increasing global concern for adverse effects of inorganic fertilizer and pesticides applied to agricultural soils. This study investigated metal speciation in soil and health risk assessment of Jute mallow (Corchorus olitoriuos) from a farm settlement in Ikorodu, Lagos State. Soil samples were collected according to the set standard procedure, sequentially extracted and analyzed for selected heavy metals using standard methods. Results showed that chromium (Cr) was associated with reducible fraction (Fe-Mn) for top soil, while cadmium (Cd), manganese (Mn), and copper (Cu); lead (Pb) and nickel (Ni); and Cr were predominantly bound to carbonate, reducible and residual mineral components respectively for sub-soil. The results of Contamination Factor (CF), Contamination Degree (CD), Pollution Load Index (PLI) and Geoaccumulation Index (Igeo) showed that the soil samples were not polluted for all the investigated metals. The Cd level in the soil (13.54 ± 1.21 mg·kg﹣1) and vegetables (0.83 ± 0.05 mg·kg﹣1) were above the USEPA critical permissible limit of 3.0 mg·kg﹣1 and 0.1 - 1.2 mg·kg﹣1 respectively. The daily intake of estimated selected heavy metals from the vegetable ranged from 8.8 × 10﹣03 to 1.4 × 10﹣02 for adult and 3.8 × 10﹣03 to 1.1 × 10﹣02 for children while the Hazard Quotient (HQ) for adults ranged from 5.4 × 10﹣05 to 1.1 × 10﹣01 and that of children ranged from 8.3 × 10﹣03 to 1.4 × 10﹣02. The cancer risk (CR) values of heavy metals in the soil ranged from 1.02 × 10﹣11 to 9.90 ×

Pollutants in soils and other environmental matrices can directly pose significant human health risks through various exposure pathways, especially for local population. The concentration and distribution of heavy metals (Pb, Ni, Cd, Cr, Fe and Zn) and the gamma ray emitting (U-238, Th-232, and K-40) radionuclides in bituminous soils were analyzed using well calibrated atomic absorption spectrophotometer (AAS) and gamma-ray spectrometry using NaI(TI) detector. The average concentration of Pb, Ni, Cd, Cr, Fe and Zn were 28.2, 24.1, 5.16, 42.5, 170 and 226 mg kg(-1) respectively. The average activity concentration of U-238, Th-232, and K-40 were 42.6 +/- 6.50, 113 +/- 10.5 and 461 +/- 24.3 Bq kg(-1) respectively. These values were above the world average value, although only six samples were higher than the world average value. The average activity concentrations, radium equivalent and dose rate of measured radionuclides were compared with other literature values and country's maximum allowable limit for heavy metals. The geo-accumulation index (Igeo), contamination factor, pollution loading index (PI), enrichment factor, and potential ecological risk index (PERI) were calculated to assess the heavy metals pollution level in soils. The total hazard index (THI) and carcinogenic risk (CR) were used to assess human health risk of heavy metals. The pollution level using the four pollution assessment model were in the order Pb > Cd > Ni > Cr > Fe > Zn. The estimated carcinogenic risk (CR) for children and adults obtained were all higher than the safe limit (1 x 10(-6)) while the non-carcinogenic risk (THI) was below the safe limit (THI (<) 1). Pollution sources were identified using multivariate statistical analysis. It was found that Cr contributed > 97% to the overall cancer risk (CR) for children and adults. The pollution sources were identified using multivariate statistical analysis. Therefore, the federal and state ministry of environment, health and solid minerals must rise to the urgent need of remediating the bituminous soil which may pose great health risk to human population in the study area.

Anthropogenically enhanced naturally occurring radionuclides U-238, Th-232 and K-40 present in the tar sand soil samples were measured by gamma ray spectrometer using a highly shielded Nal (TI) detector with the aim of evaluating the environmental radiological hazards. Mineralogical analysis and characterization was carried out using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) techniques. The results obtained showed that the average activity concentrations of U-238, Th-232 and K-40 ranges from BDL <-> 76.00 +/- 12.00, BDL <-> 204.48 +/- 13.02 and BDL <-> 755.6 +/- 40.15 Bqkg(-1) respectively. Eleven other radiological and hazard parameters were estimated to know the complete hazardous nature of the samples. The values obtained for radionuclides and all its associated radiological and health hazard parameters were all higher than the world's average set by UNSCEAR. Five different minerals were identified and characterized as major and minor minerals. The mean radionuclides activity concentrations, radium equivalent and dose rate of measured radionuclides were compared with other literature values. RESRAD computer code was used to calculate the probability of excess lifetime cancer incurred by dwellers of the tar-sand deposit site, the level of which was determined to be 2.3 x 10(-3) (223/10000). Spatial distribution of natural radionuclides in the study area was also investigated for radioactivity disequilibrium. Multivariate statistics were applied to establish the effect of mineralogy on radionuclides activity. Therefore, the tar-sand soil samples are considered to pose serious radiological hazard and cancer risk to human through the multiple routes of exposure and significant soil remediation action need to be taken for future use of the soils. (C) 2017 Elsevier Ltd. All rights reserved.

The concentration and spatial distribution of the gamma ray emitting 238U, 232Th, 40K and 137Cs radionuclides in dumpsite soils in Agbara were analyzed with the aim of evaluating the radiation hazards and excessive lifetime cancer risk using well calibrated HPGe γ-ray spectrometry technique. The ranges of activity concentrations of 238U, 232Th, 40K and 137Cs are 11.5 ± 1.0 ↔ 166 ± 40 Bq kg−1, 15.6 ± 1.8 ↔ 31.4 ± 2.3 Bq kg−1, 20.4 ± 1.3 ↔ 366 ± 30 Bq kg−1 and 0.52 ± 0.1 ↔ 8.44 ± 0.2 Bq kg−1 respectively. Radiological parameters such as absorbed dose rate, radium equivalent, annual effective dose equivalent, internal and external hazard indices, gamma level index, activity utilization index, annual genetic significant dose equivalent, exposure rate and excessive lifetime cancer risk were calculated to know the complete radiological hazardous nature of the dumpsite soils to the inhabitants of the sites. The calculated radiological parameters were higher than the world average value in two of the sampling points. The ratio of the detected radioisotopes was calculated for spatial distribution of natural radionuclides in the study area. RESRAD computer code was applied to calculate the total effective dose equivalent (TEDE). The code was also used to calculate the probability of excess lifetime cancer incurred by dwellers/inhabitants of the dumpsites, the level of which was determined to be 0.5 × 10−4 and 2.5 × 10−5 for Idowale and Ibijola dumpsite soils over a period of 30 years respectively. Therefore, the radiological risks to the general populations from waste enhanced naturally occurring radioactive materials (WENORM) from the Idowale dumpsite top soils are considered to be significant.

Environmental and health risk posed by heavy metals from municipal landfill cannot be over emphasized. However, the toxicity and fate of metal in the soil is dependent on its chemical form and therefore quantification of the different forms of metal is more meaningful than the estimation of its total concentration. This study investigated the chemical form and potential hazards of heavy metal pollution at two municipal landfills in Sagamu, Ogun state, Nigeria. Soil samples were collected around the landfills and chemical form of Cu, Zn, Cd, Pb, and Fe were studied, using the Tessier Five-step sequential chemical extraction procedure. The results showed that Cu and Fe were speciated into residual fractions with averages of 23.9 and 31.3% respectively, while Cd and Zn were associated with Carbonate fractions with respective averages of 20.3 and 20.6%. The order of mobility and bioavailability of these metals are: Cd > Pb > Cu > Zn > Fe. A comparison of the result of total extractible metals with standard set by USEPA reveals that Cd and Cu level in the dumpsite soils are far above the critical permissible limit of 3.0 and 250 mg kg−1, respectively which potent a health risk. Assessment of soil pollution level using geoaccumulation index (Igeo) revealed that the landfill was extremely polluted by Cd (Igeo > 5). Pearson correlation and principal component analysis showed that there were no significant correlations (p < 0.05) among all the metals, suggesting that they are all from different anthropogenic sources. The cancer risk ranged from 1.36E−01 to 2.18E−04 and 5.82E−01 to 9.35E−04 for Children and Adult respectively. The level of cancer risk falls above the threshold values (10−4–10−6) which US Environmental Protection Agency considered as unacceptable risk. Based on the above findings, it was suggested that environmental management policy should be implemented to decrease the environmental risks.