This study assesses the likely health risks to human contamination of heavy metals from fish consumption. The analysis of the idea of fish destination and status (fishing area) for heavy metals was determined by the assessment of its risk limits (daily intake of metal and health risk index). Variations in the accumulation of heavy metals concentrations were between various tissues/organs (skin, muscle, gills, liver, intestine, kidneys, brain, and bones) across the batches of two fishing origins. Post hoc (Duncan) multicomparison shows that there are significant differences ( < 0.05) across batches. The concentrations of heavy metals analyzed, in the investigated tissues of Scomber scombrus, showed higher levels of heavy metals accumulations in the order: Fe > Hg > Pb > Cd > Ni and were above the recommended safety limits outlined by FAO/WHO. However, the consumer's health risk with the consumption of fish muscles tissues shows that there are greater tendencies for cadmium, lead, and mercury exposure. Also consumption of Scomber scombrus species above the recommended daily intake (stated in this study) might lead to ingestion of heavy metals at unacceptable concentrations.
Due to industrialization of Kano City, more industries located within Challawa industrial estate have discharged waste informed of effluents into River Challawa, which is the main source of irrigation water for agricultural land. Hence, this study is aim at assessing the bioavailable fractions of the metals zinc (Zn), lead (Pb), copper (Cu), chromium (Cr) and cadmium (Cd) in surface water of river Challawa, Kano, Nigeria, across seasons. It was found that the concentrations of most metals increased significantly during the dry seasons. Concentrations of Cu and Zn are within the standard limits of EPA and WHO for these metals in drinking water while Pb, Cr, and Cd have their concentrations higher than EPA and WHO standard limits. Analysis of relationship between metals indicated significant positive correlation ( < 0.05) between Cr and Zn, in all seasons with exception of warm and dry season. This might explain the consistent variation of these metals in the sites in a particular season. Also, significant negative correlation was observed between Cd and Cu (hot and dry season). The chemical fractionation trends were found to be dominated by particulate fractions of metals studied except Zn (cool and dry season) and Cd. The highest percentages of all metals analysed were found in the particulate fraction with exception of Cd. This could reflect less availability of this metal to the immediate environment. However, availability of metals such as Cd, Cr, and Pb in the dissolved and mobile fractions reflects the greater tendency to become available to the aquatic system and through the food chain to man.
The crude oils and their source rocks from Niger Delta basin, Nigeria were investigated by optical microscopy for the maceral compositions and by gas chromatography - mass spectrometry (GC-MS) for the composition, distribution and abundances of saturated and aromatic biomarkers. The data obtained showed that the rock samples and crude oils were formed from the mixed input of terrestrial and marine organic matter, and deposited under oxic to sub-oxic conditions in a lacustrine-fluvial/deltaic environment. The aliphatic maturity parameters calculated for the source rocks and oil samples showed that they have immature to early mature; and early oil window maturity respectively, whereas aromatic maturity ratios indicated that they were within immature to peak of oil generation and beyond; and peak to late oil generative window, respectively. The crude oils and source rocks were characterized by the dominance of C 2 -fluorenes over other alkylated homologues. The predominance of C 2 fluorenes over other alkylated homologues might have been influenced by source facies and depositional environments. The relative percentages of fluorenes (FLs %), dibenzofurans (DBFs %) and dibenzothiophenes (DBTs %) values for the rock samples range from 9.36 to 38.04 %, 35.82–71.60 % and 10.02–42.52 %, respectively, while the crude oils have ranges of values from 18.91 to 56.38 %, 24.90–72.34 % and 5.99–19.02 %, respectively. These values showed that the crude oils and source rocks originated from the mixture of organic matter (terrestrial and marine) with higher contribution from terrestrial organic matter and deposited in a marine/brackish-saline lacustrine/swampy environments. The abundance and distribution of fluorenes and its derivatives were found to be effective in determining the origin and depositional environments of crude oils and source rocks in the Niger Delta Basin, Nigeria.
This study was initiated as a follow-up information on some impounded products chocolates and candies (Samples A, B, C and D) imported from overseas, and sold in Nigeria markets. This result as their failure to meets Nation Agency for food drug administration and control (NAFDAC) regulatory standard. Samples of these products were collected in five markets of each six states each from the six geographical zones: North-West (Bauchi), North-East (Kano), North-Central (Kogi), South-West (Lagos), South-East (Abia), and South-South (Rivers) of the country. In order to evaluate the quality of the products, the levels of some heavy metals (Cu, Mn, Fe, Ni, Zn, Ti and Cr) were evaluated in the samples using X-ray fluorescence (XRF). Concentrations of metals in both chocolates and candies ranged 3.0 -4.2 mg/g for Cu, 40.0 -55.7 mg/g for Mn, ND -102.5 mg/g for Fe, ND -305.0 mg/g for Ni, ND -42.5 mg/g for Zn, ND -23.8 mg/g for Ti, and ND -10.8 mg/g for Cr. The results showed that that these metals are at higher levels in Samples A, B, C and D compared to other studies in candies and chocolates in Nigeria. Correlation analysis among metals revealed positive correlations, which indicates similar sources of these metals. Also, evaluation of dietary intake of these products daily revealed that Samples A (except for Cu), B and C are above the daily dietary recommended limit for all the studied metals in food. Thus a frequent intake of these contaminated products is likely to induce health effects arising largely from Cu, Mn, Fe, Ni and Zn.
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