Distribution and Multivariate Pollution Risks Assessment of Heavy Metals and Natural Radionuclides Around Abandoned Iron-Ore Mines in North Central Nigeria

Abstract

The Itakpe abandoned iron-ore mines constitute the largest iron-ore deposits in Nigeria with an estimated reserve of about three million metric tons of ore. The present effort is a part of a comprehensive study to estimate the environmental and radiological health hazards associated with previous mining operations in the study area. In this regard, heavy metals (Fe, Zn, Cu, Cd, Cr, Mn, Pb, Ni, Co and As) and natural radionuclides (U, Th and K) were measured in rock, soil and water samples collected at different locations within the mining sites. Atomic absorption and gamma-ray spectrometry were utilized for the measurements. Fe, Mn, Zn, Cu, Ni, Cd, Cr, Co Pb and As were detected at varying concentrations in rock and soil samples. Cd, Cr, Pb and As were not detected in water samples. The concentrations of heavy metals vary according to the following pattern; rock ˃ soil ˃ water. The mean elemental concentrations of K, U and Th are 2.9%, 0.8 and 1.2 ppm and 1.3%, 0.7 and 1.7 ppm, respectively, for rock and soil samples. Pearson correlation analyses of the results indicate that the heavy metals are mostly negatively correlated with natural radionuclides in the study area. Cancer and non-cancer risks due to heavy metals and radiological hazards due to natural radionuclides to the population living within the vicinity of the abandoned mines are lower than acceptable limits. It can, therefore, be concluded that no significant environmental or radiological health hazard is envisaged.

Monte Carlo approach to risks assessment of heavy metals at automobile spare part and recycling market in Ilorin, Nigeria

“…glass wares and digestion vessels) were washed thoroughly before use, rinsed and purified with de-ionized water. Precision and accuracy of the measuring procedures were made certain through the reagent blanks and duplicate samples preparation 31 , 32 .…”

“…The carcinogenic risk assessment is used in the estimation and determination of the possibility of a population acquiring cancer of any kind after exposure to carcinogen. Incremental Lifetime Cancer Risk (ILCR ) is estimated as the incremental probability of a person developing cancer over a period of time due to exposure to HMs 6 , 31 . The formula is given as; where ILCR is the probability of an individual exposed to carcinogenic HMs to develop cancer over a period of time.…”

“…Table 10. Estimated annual dose intake of heavy metals in the top soil samples collected within the study site 31,35 .…”

“…Estimated mean HI and ILCR of the heavy metals in soil samples collected within the study site31,35 . Exposure parameters used in calculating the human health risks31,38 .…”

“…Estimated mean HI and ILCR of the heavy metals in soil samples collected within the study site31,35 . Exposure parameters used in calculating the human health risks31,38 . × 10 −2 ), Zn ( 3.00 × 10 −1 ), Cu (4.00 ×10 −2 ), Cr (3.00 ×10 −3 ), Cd ( 1.00 × 10 −3 ), Ni ( 2.00 × 10 −2 ), Pb ( 3.50 × 10 −3 ), As ( 3.00 × 10 −3 ), Cd (1 × 10 -3 ) Inhalation RfD:Mn ( 1.43 × 10 −5 ), Zn ( 3.00 × 10 −1 ), Cu(4.02 ×10 −2 ), Cr (2.86 ×10 −5 ), Ni ( 2.06 × 10 −2 ), Co ( 5.71 × 10 −6 ), Pb ( 3.25 × 10 −3 ), As ( 3.01 × 10 −4 ), Cd (5 .70 × 10 −5 ) Dermal RfD: Mn ( 1.84 × 10 −3 ), Zn ( 6.00 × 10 −2 ), Cu (1.20 ×10 −2 ), Cr (6.00 ×10 −5 ), Cd (5 .00 × 10 −4 ), Ni ( 5.40 × 10 −3 ), Co ( 1.60 × 10 −2 ), Pb ( 5.25 × 10 −4 ), As (1.23 ×10 −4 )…”