HEAVY METALS POLLUTION AT MUNICIPAL SOLID WASTE DUMPSITES IN KANO AND KADUNA STATES IN NIGERIA

Soil samples collected from two major dumpsites each in Kano and Kaduna states were investigated for heavy metals pollution. Each of the dumpsite was divided into north, south, east and west. Four soil samples were collected at a depth of 0-15 cm from each part and pooled to form a composite sample. Soil samples from reserve areas within the same geographical locations as the dumpsites were collected as control. Acid-extractable cadmium (Cd), chromium (Cr), nickel (Ni) and lead (Pb) were determined using 2 M nitric acid solution and atomic absorption spectroscopy. The ranges of Cd, Cr, Ni and Pb levels for all the dumpsites were 0.30–49.8, 5.76–139, 0.39–19.1 and 42.6–9662 mg/kg, respectively. Kano dumpsite 2 was found to pollute most with Cd, Cr and Pb in 50-100 % soil samples collected having concentrations higher than the threshold limits set by regulatory body. Paper and food scraps showed higher percentages in both Kano and Kaduna dumpsites. The soil was high is sand for all the dumpsites implying high leaching potentials of the heavy metals pollutants

Assessment of water and sediment around a lead-acid battery plant dumpsites in South-Western Nigeria

In a quick assessment carried out around dumpsites of a battery manufacturing plant, heavy metals content of sediment, surface water and ground water samples from seven ponds, three streams and a well were assessed using Atomic Absorption Spectrophotometer (AAS). Some physicochemical parameters of the samples were also investigated. Metal concentration in pond and stream sediment samples ranged from 25.71-75,843 μg/gPb, 0.74-4.13 μg/gCd, 32.35-385.31 μg/gCu, 3.17-28.5 μg/gNi, 558.25-908.42 μg/gFe and 10.01-53.59 μg/gZn and these metal concentrations exceeded allowable guidelines for sediment by USEPA. For water samples in general, concentration of metals ranged as Pb(0.001-5.69 mg/L), Cd(0.0006-0.0699 mg/L), Cu(0.001-0.09 mg/L), Ni(0.001-0.38 mg/L), Fe(0.0399-17.099 mg/L) and Zn(0.001-0.14891 mg/L). Physicochemical parameters in water were pH (4.54-7.59), Temperature (25-28 OC), DO (2.49-6.45 mg/L), TS (296-35,100 mg/L), TSS (2.0-281 mg/L), TDS (290-34,800 mg/L), Cl- (12.2-52.5 mg/L), NO3- (3.2-800 mg/L), PO43- (0.14-1.58 mg/L) and SO42- (76.0-5,300 mg/L). Results obtained for TSS, TDS, NO3-, SO42-, Pb, Cd and Fe in water, especially in ponds at Ile-Igbon and Ni in Aweere Stream, exceeded limits set by standard organisations as well as results from similar work

Toxic metal levels in Nigerian electronic waste workers indicate occupational metal toxicity associated with crude electronic waste management practices

The poor management of electronic wastes (e-waste) in Nigeria exposes workers to toxic chemicals in waste electrical and electronic equipment. In this study, we evaluated the toxic metal levels in Nigerians occupationally exposed to e-waste. Whole blood levels of Lead (Pb), Mercury (Hg), Arsenic (As), Cadmium (Cd), and Chromium (Cr) were determined in Nigerian e-waste workers (n=63) and in age-matched non-exposed participants (n=41), using standard electrothermal atomic absorption spectrometry and inductively coupled plasma-mass spectrometry methods. The results showed statistically significant (p<0.01) elevated body burden of toxic metals in e-waste workers (Pb, 0.95 ± 0.00 µmol/L; Cr, 405.99 ± 6.34 µmol/L; Cd, 108.54 ± 1.60 nmol/L; As, 10.09 ± 0.01 µmol/L; and Hg, 25.02 ± 0.14 nmol/L) compared with non-exposed group ((Pb, 0.03 ± 0.00 µmol/L; Cr, 178.44 ± 5.99 µmol/L; Cd, 56.99 ± 1.42 nmol/L; As, 1.02 ± 0.0008 µmol/L; and Hg, 1.62 ± 0.0672 nmol/L). These data indicate that the elevated body burden of toxic metals in the e-waste exposed  population is an indication of occupational metal toxicity associated with crude e-waste management practices in Nigeria. In addition, the potential health implications of exposure to these toxic metals, such as chronic kidney disease, cancer; preceded by genome instability and depressed immune response were highlighted.Keywords: Metal toxicity, e-waste, Nigeria, Occupational exposure

Surface Mixed Layer Profile of Physical and Biogeochemical Variables in the Subpolar North-West and -East Atlantic Ocean: A Data-Model Comparison Study

This paper presents a study of physical and biogeochemical variables using numerical model and mixed layer oceanographic data from a 2 - 3 year in situ measurements in the Northwestern and Northeastern sites of the Atlantic Ocean. Model outputs are presented and indicated that very good estimates may be obtained. The outputs showed considerable agreement in reproducing seasonal distributions of pCO2, pCO2-T, pCO2-nonT, mixed layer temperature, and chlorophyll-a in both winter and summer, and therefore provide useful physical and theoretical understanding of their biogeochemistry. The model pCO2 indicated a distinct temporal variability with seasonal changes coinciding with the change in sea surface temperature. It also provides an agreement that there is a strong seasonal cycle of mixed layer parameters filliped by nonthermal and physical factors. As an outgrowth of this work, the pCO2 model outputs affirm the North Atlantic Ocean capacity as an important oceanographic sink for anthropogenic carbon dioxid

Toxic metal levels in Nigerian electronic waste workers indicate occupational metal toxicity associated with crude electronic waste management practices

The poor management of electronic wastes (e-waste) in Nigeria exposes workers to toxic chemicals in waste electrical and electronic equipment. In this study, we evaluated the toxic metal levels in Nigerians occupationally exposed to e-waste. Whole blood levels of Lead (Pb), Mercury (Hg), Arsenic (As), Cadmium (Cd), and Chromium (Cr) were determined in Nigerian e-waste workers (n=63) and in age-matched non-exposed participants (n=41), using standard electrothermal atomic absorption spectrometry and inductively coupled plasma-mass spectrometry methods. The results showed statistically significant (p<0.01) elevated body burden of toxic metals in e-waste workers (Pb, 0.95 \ub1 0.00 \ub5mol/L; Cr, 405.99 \ub1 6.34 \ub5mol/L; Cd, 108.54 \ub1 1.60 nmol/L; As, 10.09 \ub1 0.01 \ub5mol/L; and Hg, 25.02 \ub1 0.14 nmol/L) compared with non-exposed group ((Pb, 0.03 \ub1 0.00 \ub5mol/L; Cr, 178.44 \ub1 5.99 \ub5mol/L; Cd, 56.99 \ub1 1.42 nmol/L; As, 1.02 \ub1 0.0008 \ub5mol/L; and Hg, 1.62 \ub1 0.0672 nmol/L). These data indicate that the elevated body burden of toxic metals in the e-waste exposed population is an indication of occupational metal toxicity associated with crude e-waste management practices in Nigeria. In addition, the potential health implications of exposure to these toxic metals, such as chronic kidney disease, cancer; preceded by genome instability and depressed immune response were highlighted

Polychlorinated Biphenyls in Brackish Water Fish in the River Niger, Nigeria

Background. Anthropogenic polychlorinated biphenyls (PCBs) in aquatic environments poses human and ecological health risks in Nigeria. Objectives. This study determined the concentrations of PCBs in brackish water fish in the River Niger to assess the contamination status of fish consumed by the local population. Methods. The sampled fish species included Drepane africana, Mochokus niloticus, Chrysichthys nigrodigitatus, Pristipoma jubelini, Vomer septapinis, Pseudotolithus senegalensis, Mugil cephalus, Pseudotolithus elongatus, Sphyraena piscatorum and Lutjanus goreensis, purchased from landing sites. Six fish from each species were sampled, for a total of 60 samples. Twenty-seven (27) PCB congeners, #8, #18 #28, #44, #52, #60, #77, #81, #101, #105, #114, #118, #123, #126, #128, #138, #153, #156, #157, #167, #169, #170, #180, #185, #189, #195, and #206 were screened in the fish samples using standard methods. The PCBs were identified and quantified using gas chromatography (GC) (Hewlett Packard GC 5890 series 11 with electron capture detector). Confirmation was performed using Shimadzu GCMS QP2010. Results. The sum of the National Oceanic and Atmospheric Administration Agency (ΣNOAA) PCBs occurred at the highest concentration of 1830.0±484.0 μg/kg detected in Vomer septapinis, and the lowest in Pseudotolithus senegalensis, with a mean concentration of 795±169.3 μg/kg. The concentration of dioxin-like (DL) PCBs was highest in Pristipoma jubelini (992.0±88.6 μg/kg) and lowest (285.6±81.5 μg/kg) in Drepane africana. The highest mean concentration (418.±177.6 μg/kg) of International Council for the Exploration of the Seas-7 (ICES-7) PCBs was observed in Vomer septapinis. The heavier ICES-7 congeners PCB-138, PCB-153, and PCB-180 occurred at higher concentrations compared to the lighter molecular weight ICES-7: PCB-28, PCB-52, and PCB-101. The European Union (EU) marker PCB limit of 335 μg/kg was exceeded in all the brackish water fishes with the exception of Mochokus niloticus, Pristipoma jubelini and Pseudotolithus senegalensis. Discussion. The total level of PCBs in the brackish fish samples was relatively high at >1000 μg/kg (above the World Health Organization (WHO) and Food and Agriculture Organization of the United Nations (FAO) guideline of 1000 μg/kg fresh weight). The EU guideline value for fish (220 μg/kg fresh weight) was exceeded in about 80% of the brackish fish samples studied. Conclusions. Consumption of fish from the River Niger may expose humans to polychlorinated biphenyls. In addition, since contamination of the fish samples is an indication of river contamination, river water quality is of great concern and there is a need for additional PCB data on water quality to be distributed to the community, followed by mitigation measures. Competing interests. The authors declare no competing financial interests

Initial Inventory of Plastics Imports in Nigeria as a Basis for More Sustainable Management Policies

Background. Plastic is a waste stream with recycling and recovery potential. However, the recycling rates for plastic in African countries are low. Furthermore, use and production of virgin plastics are increasing. Therefore, a high proportion of plastic waste is being disposed of in landfills and dumpsites. Plastic serves as fuel for open burning at landfills/dumpsites with associated releases and constitutes a large fraction of marine litter, making it a major and growing global pollution concern. Objectives. This study aims to develop an initial inventory of plastics in Nigeria towards the development of an effective plastics management frame. Methods. A search was conducted of the recent literature and the United Nations (UN) Comtrade database using harmonized system (HS) codes for import data of various polymer categories and major product categories containing plastic. Algebraic expressions were developed for calculation of the share of plastic in these products. Results. Approximately 14,200,000 tons of plastics in primary form were imported into Nigeria between 1996–2014. Approximately 3,420,000 tons total plastic were imported in the form of products and approximately 5,545,700 tons were imported as product components. Approximately 194,000 tons of plastic toys were imported over a six-year period. Discussion. The total amount of plastics imported in primary form and as products equals 17,620,000 tons. The total volume of imported plastic, newly produced plastic and plastic components going into the technosphere was 23,400,000 tons. The huge amount of plastic and other polymers entering the technosphere in Nigeria has important implications for marine litter, pollution, waste management and resource recovery. Conclusions. A huge volume of plastics has entered the Nigerian technosphere, with less than 12% of the resulting waste entering the recycling stream. There is a need for sustainable management of this crucial waste and resource category. Potential mitigating strategies include waste plastic reuse, recycling, waste conversion to energy, and appropriate plastic control policy frameworks. Competing Interests. The authors declare no competing financial interests

Pollution vulnerability and health risk assessment of groundwater around an engineering landfill in Lagos, Nigeria

Solid wastes disposal, through the use of non-sanitary landfill facility has tremendous health impacts on man and environment, yet without regard to environmental consequences, the use of controlled dumpsite is at best a common practice in underdeveloped countries. The paucity of data on modelling of potential vulnerability of neighboring aquifer to the pollution from Soluos dumpsite (a non-engineering landfill) necessitate the study of the use of a model DRALTC (modified DRASTIC) on the estimation of vulnerability of groundwater to dumpsite pollution and associated health risks. Six hydrogeological factors: Depth to water, net recharge, aquifer media, distance of wells to dumpsite, topography, and clay content, were involved in the modification of the model (DRALTC) which helps in characterizing the hydrogeological setting of the study area and estimation aquifer vulnerability. Sodium adsorption ratio (SAR) and permeability index (PI) were used to analyse the data generated in this study. The health risk indices (HRI) were also estimated for trace metals in the groundwater samples. The pollution vulnerability ranged between (161 and 175) moderate and high groundwater pollution potential. SAR results observed in this study reveal 25% excellent, 20 % good, 10% doubtful and 45% unsuitable. The order HRI observed was Cd > Zn > Cu > Ni > Pb for adult, while Cd > Cu > Ni > Zn >Pb trend was found for children, though the HRI value for all the metals investigated were within the safe limit (HRI < 1.0) suggesting no health risk