Seasonal variations in heavy metal concentrations in soil and some selected crops at a landfill in Nigeria

In this study, the seasonal variations in concentrations of the heavy metals - As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn - in soil and crops from a farm near the refuse dump site of Obafemi Awolowo University, Ile-Ife, Nigeria were investigated during the two major seasons of Nigeria. This was done to assess the pollution status of the farm and hence the safety levels of the crops produced. Soil and crop samples collected during the 2005/2006 rainy and dry seasons were treated and digested using standard wet digestion methods. Heavy metals were determined with Atomic Absorption Spectrophotometer (AAS). Analytical results of soil from landfill indicated that in the wet and dry seasons, values for Cd, Cu, Fe, Ni, Cr, Zn, Co and Pb were higher than normal levels of a typical agricultural soil, but As (3.20 and 4.13 mg/kg) was found to be within the acceptable range while Mn values of 597.00 - 828.37 mgkg-1 were slightly above the usual background levels. The study showed highest concentrations of As (8.31 mg/kg), Cr (9.00 mg/kg) and Ni (40.00 mg/kg) in Manihot esculenta leaves; Cu (25.0 0 mg/kg) and Fe (176.00 mg/kg) in Xantosoma mafaffa tuber; Cd (14.50 mg/kg), Co (22.50 mg/kg), Mn (189.50 mg/kg), Pb (680.00 mg/kg) and Zn (440.59 mg/kg) in Talinum triangulare. In general, the levels of heavy metals in soil and crops were higher in the dry season than in the wet season, but this difference is not statistically significant. Particularly, the levels of As, Cd, Cr, Ni, and Pb were above the critical toxic level in plant leaves in both dry and wet seasons while Zn and Cu occurred at toxic levels only in the dry season.Key words: Contamination, heavy metals, landfill, refuse dump, transfer factor

Essential and Non-Essential Metals Profile in Blood of some Nigerian Pregnant Women

In this study, the concentrations of some essential (Ca, Cu, Fe, Mg, Mn, Ni, and Zn) and non-essential metals (Cd and Pb) were determined in blood of pregnant women aged between 15 \u2013 45 years and enrolled at the Obafemi Awolowo University Teaching Hospitals Complex, Ile \u2013 Ife, Nigeria, for antenatal care. Fifty samples of whole blood were collected from the pregnant women and twenty five samples from non pregnant women as control. Levels of essential and non- essential metals were determined by atomic absorption spectrophotometry. The analyses were performed in order to assess the body burden of pregnant women with the metals and the health implications of the latter to pregnant women and their fetuses. Data analysis by descriptive and inferential statistics revealed that age, education, and profession correlate with the levels of the metals. The mean levels of the two non-essential metals obtained in this study were lower than the recommended limits for whole blood. While compared with other studies of pregnant women elsewhere results obtain were generally higher. Generally the values obtained in this study have indicated no serious body burden on the pregnant women. The importance of establishing factors that influence low human exposure concentrations is becoming critical in efforts to reduce exposures and hence the potential for adverse health effects

Bromate and trace metal levels in bread loaves from outlets within Ile-Ife Metropolis, Southwestern Nigeria

Bread loaves randomly sampled from nine outlets and bakeries within Ile-Ife were analysed to determine their safety levels for human consumption with respect to bromate and trace metal contents. Bromate determination was carried out via spectrophotometric method while trace metals in the digested bread samples were profiled using Flame Atomic Absorption Spectrophotometer. Bromate levels in the analyzed bread samples ranged from 2.051 ± 0.011 μg/g to 66.224 ± 0.014 μg/g while the trace metal levels were of the order: 0.03–0.10 μg/g Co = 0.03–0.10 μg/g Pb < 0.23–0.46 μg/g Cu < 2.23–6.63 μg/g Zn < 25.83–75.53 μg/g Mn. This study revealed that many bread bakers around Ile-Ife had not fully complied with the bromate-free rule stipulated by NAFDAC contrary to the “bromate free” inscribed on the labels of the bread. The bread samples contained both essential and toxic trace metals to levels that could threaten the health of consumers over prolonged regular consumption

Concentrations of Polybrominated Diphenyl Ethers (PBDEs) in Water from Asunle Stream, Ile-Ife, Nigeria

This study assessed the concentrations of polybrominated diphenylethers (PBDEs) in stream water obtained from Asunle stream, an adjoining stream of the Obafemi Awolowo University dumpsite. Water samples were collected for a period of eight months from six different locations comprising of a spot upstream in an uphill area relative to the refuse dumpsite and five others downstream along the stream course. The sampled waters were extracted with dicholoromethane using liquid-liquid extraction method and cleanup was carried out with silica gel. The final extracts after concentration were analyzed using GC-MS/MS. The recovery experiments were adequate (105%–110%). The mean levels of Ʃ6PBDEs compounds analyzed ranged from 0.03 to 0.45 ng/mL. Seasonal variability of PBDEs indicated that higher levels were found during the wet season. The levels of PBDEs recorded in this work were relatively lower compared to the values reported in the literature from other developed nations

Speciation study of the heavy metals in commercially available recharge cards coatings in Nigeria and the health implication

This work assessed levels of heavy metals exposure from silver coatings of mobile phones recharge cards of three major companies (designated as A, B and C) with price denominations 100, 200 and 400 from companies A, B and C respectively, which were carefully scratched using a plastic scraper into a glass tube. The coatings were acid digested for total metal concentration, while speciation experiment for Mn, Cu, Cd and Pb was carried out. Total metals and speciation analysis were done using AAS and XRF techniques. The total metal concentration from XRF analysis was in the range: Ca (70–2140 μg/g), K (20–4930 μg/g), Sc (80–270 μg/g), Ti (1530–12,580 μg/g), Fe (50–6660 μg/g), Ni (20–2040 μg/g), Cu (20–850 μg/g) and Zn (40–460 μg/g). Cr had the lowest concentration (10 μg/g) in A (400) while Ti had the highest concentration (12,580 μg/g) in C (500) for all the coatings analyzed. AAS and XRF results agreed closely except for Fe with higher concentration. A (100) contained high concentration of the metals compared with others. Speciation study identified Mn as the most mobile element when present in the environment