In this study, we evaluated the concentrations, composition, sources, and potential risks of polycyclic aromatic hydrocarbons (PAHs) in soils, and indoor and outdoor dust from Port Harcourt city in ...Nigeria. Gas chromatography-mass spectrometry (GC-MS) was used for the detection and quantification of PAH species in the samples. The concentrations of the US EPA 16 PAHs plus 2-methyl-naphthalene (∑17 PAHs) in soils, and indoor and outdoor dust from Port Harcourt city ranged from 240 to 38 400, 276 to 9130 and 44 to 13 200 μg kg
−1
(dry weight, d.w.) respectively. The PAH concentrations in these matrices followed the sequence: soil > indoor dust > outdoor dust. The composition of PAHs in soils and dust (indoor and outdoor) showed remarkable differences with prominence of 3- and 5-ring PAHs. The estimated carcinogenic risk to the residents arising from exposure to these concentrations of PAHs in soils, and indoor and outdoor dust from Port Harcourt was above the acceptable target cancer risk value of 10
−6
. We concluded that these sites require clean-up, remedial actions and implementation of stringent pollution control measures with the intention of reducing the undesirable impacts of PAHs on both the ecosystem and humans.
This study evaluated the concentrations, composition, sources, and potential risks of polycyclic aromatic hydrocarbons (PAHs) in soils, and indoor and outdoor dust from Port Harcourt city in Nigeria.
In this study, the concentrations of 28 polychlorinated biphenyl (PCB) congeners, including 12 dioxin-like PCBs and 7 indicator PCBs, were determined in sediments around oil production facilities in ...the Escravos River Basin of the Niger Delta in Nigeria. The aim was to describe the spatial patterns, sources, and ecosystem risks associated with exposure to PCBs in sediments of this river basin. Gas chromatography-mass spectrometry (GC–MS) was used to determine the concentrations of PCBs in the sediments. The Ʃ28 PCB concentrations in sediments from the Escravos River Basin ranged between 226 and 31,900 ng g−1 with a median concentration of 2300 ng g−1. The results indicated that sediments around crude oil production facilities, such as, wellheads, flow stations, and truck lines, had significantly higher levels of Ʃ28 PCBs (p < 0.05) than those collected near residential communities within the river basin. The median concentrations of PCB homologues in sediments from this river basin followed the sequence: hexaPCBs > penta-PCBs > tetra-PCBs > hepta-PCBs > tri-PCBs > di-PCBs > deca-PCBs > octa-PCBs > nona-PCBs. The risk assessment of PCBs in sediments from this river basin suggest very high potential risks for both organisms and humans.
•PCBs were measured in sediments from the Escravos River Basin.•Low chlorinated PCBs were dominant in the sediments.•Potential ecological risk exists for exposure of organisms to PCBs in sediments.•PCBs in the sediments are associated with inadvertent sources.
This study investigates the concentrations, sources, and ecological and human health risks resulting from exposure to polycyclic aromatic hydrocarbons (PAHs) in soils of rural communities around gas ...flaring points in Delta State, Nigeria. PAHs were extracted from these soil samples with hexane/dichloromethane by ultra-sonication and the extracts were cleaned on a silica gel/alumina-packed column. The PAH concentrations in the extracts were quantified by gas chromatography-mass spectrometry (GC-MS). The 16 PAH concentrations in soils from these communities varied from 2370134000, 461389000, and 213034900 g kg
1
for Emu-Ebendo (EME), Otu-Jeremi (OTJ) and Ebedei (EBD), respectively. The estimated lifetime carcinogenic risk values recorded in this study were above the acceptable limit of 10
6
, indicating a high potential carcinogenic risk resulting from human exposure to PAHs in these soils. The isomeric ratio and principal component analysis results suggest that emissions from high-temperature combustion, potentially gas flaring, vehicular emissions, burning of wood/biomass, and fossil fuel combustion are responsible for the high concentrations of PAHs in soils of these rural communities. This study recommends implementing remediation and source control measures to minimise the impact of PAHs in the affected soils on humans and the environment.
This study investigates the concentrations, sources, and ecological and human health risks from exposure to polycyclic aromatic hydrocarbons (PAHs) in soils of rural communities around gas flaring points in Delta State, Nigeria.
Indoor and outdoor dust from three rural communities (Emu-Ebendo, EME, Otu-Jeremi, OTJ, and Ebedei, EBD) around gas flaring points, and a rural community (Ugono Abraka, UGA) without gas flare points, ...in the Niger Delta of Nigeria, was analysed for the concentrations and distribution of polycyclic aromatic hydrocarbons (PAHs), their sources, and possible health risk resulting from human exposure to PAHs in dust from these rural communities. The PAHs were extracted from the dust with a mixture of dichloromethane/
n
-hexane by ultrasonication, and purified on a silica gel/alumina packed column. Gas chromatography-mass spectrometry was employed to determine the identity and concentrations of PAHs in the cleaned extracts. The Σ16PAH concentrations in the indoor dust ranged from 558 to 167 000, 6580 to 413 000, and 2350-37 500 μg kg
−1
for EME, OTJ and EBD respectively, while those of their outdoor counterparts varied from 347 to 19 700, 15 000 to 130 000, and 1780 to 46 300 μg kg
−1
for EME, OTJ and EBD respectively. On the other hand, the UGA community without gas flare points had Σ16PAH concentrations in the range of 444-5260 μg kg
−1
for indoor dust, and 154-7000 μg kg
−1
for outdoor dust. The lifetime cancer risk values for PAHs in these matrices surpassed the acceptable limit of 10
−6
suggesting a potential carcinogenic risk resulting from human exposure to PAHs in indoor and outdoor dust from these rural communities. Principal component analysis suggested that PAH contamination of dust from these communities arises principally from gas flaring, combustion of wood/biomass, and vehicular emissions.
Indoor and outdoor dust from three rural areas around gas flaring points, and a rural area without such points in the Niger Delta of Nigeria, was analysed for the concentrations and distribution of PAHs, their sources, and possible health risk.
This study assessed the concentrations, sources, and risks of polycyclic aromatic hydrocarbons (PAHs) in sediments from the Rivers Niger, Ase and Forcados in the western Niger Delta. The ...concentrations of PAHs (in μg kg−1 dry weight), as determined by gas chromatography–mass spectrometry, in sediments from these rivers varied from 2400 to 19,000, 2930 to 16,100, and from 1620 to 19,800 for the Niger, Ase and Forcados Rivers respectively. High molecular weight (HMW) PAHs were the most prevalent compounds present in these sediments. An assessment of the possible ecological and human health risks suggested high risks for both organisms and humans. The PAH source analysis suggested that sediments from these river systems were contaminated with PAHs arising from burning of biomass, gasoline/diesel emissions, burning of natural gas, and oil spillages.
•Sediments from the Niger, Ase and Forcados Rivers were contaminated with PAHs.•The PAH composition in these sediments showed prominence of 5- and 6-ring PAHs.•There is a high risk to both organisms and humans from these PAHs in sediments.•Remedial actions and stringent control measures are required to reduce this risk.•Possible sources of this PAH contamination have been identified.
The concentrations of metals (Cd, Pb, Ni, Cr, Cu, Co, Fe, Mn, and Zn) were determined in selected brands of canned mackerel, sardine, and tuna in Nigeria with a view to providing information on the ...dietary intakes of metals and lifelong health hazards associated with the consumption of these products. The concentrations of metals were determined by using atomic absorption spectrometry after acid digestion. The mean concentrations of metals in canned mackerel, sardine, and tuna were found as 0.04–0.58, 0.06–0.44, 0.32–0.83 μg/g for Cd; 0.05–2.82, 0.70–2.98, 0.23–2.56 μg/g for Pb, 1.33–11.33, <0.20–17.53, nd–34.2 μg/g for Ni, 0.49–3.79, 0.22–1.89, 0.66–14.39 μg/g for Cr, 0.33–0.92, 0.03–1.51, <0.08–1.31 μg/g for Cu, 0.11–2.17, nd–0.75, 0.14–0.50 μg/g for Co, 6.45–26.90, 6.06–53.54, 3.06–95.78 μg/g for Fe, 2.30–3.84, 0.95–21.78, 1.65–2.33 μg/g for Mn, 1.15–7.19, 3.60–17.88, 1.21–5.35 μg/g for Zn, respectively. The mean concentrations of Cd, Pb, and Fe in some of these brands of canned fish were above their permissible limits while other metals occurred at levels below their permissible limits. The estimated daily intakes of metals from consumption of 20.8 g fish per day by a 60 kg body weight adult were below the provisional tolerable daily intakes for Cd, Pb, Ni, Cr, and Cu and recommended daily intakes for Co, Fe, Mn, and Zn. The estimated target hazard quotients of the examined metals were less than 1 in the majority of the samples indicating no long-term health hazard at the present circumstance.
The levels of Cd, Pb, Cr, Ni, Cu, Co, Ba, Mn, Zn, Al and Fe were evaluated in indoor dusts from electronic workshops, cybercafés and offices in southern Nigeria. The study was aimed at providing ...information on the distribution patterns, and the associated risks that may arise from exposure of humans to these metals in indoor dusts from the three work environments. The dust samples were digested with aqua-regia and analyzed for the metal concentrations by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The metal concentrations (mg kg−1) in the indoor dusts from these work environments ranged from 0.2 to 20.5 Cd, 0.6–4810 Pb, 8.65–2210 Cr, 1.85–209 Ni, 6.75–2820 Cu, 0.25–19.6 Co, 22.7–597 Mn, 6.65–140 Ba, 43.3–7310 Zn, 1040–16,800 Al and 969–78,300 Fe. The metal distribution patterns in these dust samples followed the order: electronic workshops > cybercafés > offices. The concentrations of Cd, Pb and Cu in significant proportions of the dust samples from the electronic workshops and cybercafés surpassed their respective permissible limits in soils. The health risk assessment suggests considerable non-cancer risks arising from childhood contact with Pb in dust from the electronic workshops while no considerable non-cancer risk is associated with the adult and child exposure to dust from the cybercafés and offices. The results indicated that Cr and Pb are the main elements responsible for the non-carcinogenic risk arising from childhood exposure to electronic workshop dusts. The carcinogenic risk due to exposure of humans to metals in these dust samples were within the range regarded as safe by the USEPA.
•Considerable non-cancer risks for childhood contact with Pb in electronic workshop dusts.•Cr and Pb are the main elements responsible for the non-carcinogenic risk.•No considerable cancer risk from exposure of humans to dust-borne metals.
The concentrations of metals (Cd, Pb, Ni, Cr, Cu, Fe, Mn and Zn) were determined in soils under different land use types in an urban environment in order to study the impact of land uses on the ...concentrations of metals in the soils. The mean concentration range of metals for all land use types were 42.1 to 410, 11.2 to 118.2, 4388.2 to 31891.1, 9.7 to 65.4, 0.1 to 1.8, 4.7 to 35.2, 2.0 to 16.8 and 77.9 to 881.7 mg/kg, for Mn, Pb, Fe, Cu, Cd, Cr, Ni and Zn, respectively. The computed multiple pollution index (MPI) indicated that 67 % of the examined sites had MPI values between 1 and 20 i.e. at the pollution range, while 33 % of sites had MPI values of zero which indicated that these sites were not polluted with the studied metals. Zinc had the highest impact on the multiple pollution index values. Three main principal components were identified from the principal component analysis which include (i) Cu, Zn, Pb, Cr and Ni originating from both industrial and agricultural sources, and as well as automobile exhausts; (ii) Fe and Mn which originated from both natural and anthropogenic sources; (iii) Cd which its anthropogenic origin is different from components I and II. This study provided information on the sources of metals in the urban environment and extent of contamination associated with each land use, which are useful in the ranking of contaminated sites, environmental quality management, environmental forensic studies and guidance for remediation/redevelopment of contaminated land.
Concentrations of metals in household dust samples from rural, semi-urban and urban zones of the Niger Delta in Nigeria were measured during both 2009 and 2014 with the aim of providing information ...on changes in the concentrations, distribution patterns, sources and risks of metals in these zones. The concentrations of metals in the dust samples were quantified by using inductively coupled plasma atomic emission spectrophotometry (ICP-AES) after digestion with aqua regia. The measured concentrations (mg kg
−1
) of metals in the three zones within the study periods were as follows: <LOQ–21.2; <LOQ–182; 7.90–265; <LOQ–117; <LOQ–471; 3.37–2310; 0.35–7.9; 4.25–365; 6.78–61,600; 219–37,700; and 1180–18,000 for Cd, Pb, Ba, Cr, Ni, Cu, Co, Mn, Zn, Fe and Al, respectively. The results from the two periods indicate significant changes in the concentrations, distribution patterns and risk factors which reflects a deterioration of the quality of the household environment over this time span. The hazard index (HI) values calculated for children were greater than 1 indicating significant non-cancer risks for these subjects in these areas. The HI values for adults were less than 1 and consequently do not pose a significant risk. The carcinogenic risk levels for exposure to metals for both adults and children in these zones were below the range specified as safe by the US EPA (×10
−6
and ×10
−4
) thereby indicating a low cancer risk. The sources of metals in household dust from these zones include emissions from industries, traffic, artisanal workshops and releases from household furniture, metal-based fittings, metal roofing and pesticides.
The concentrations of the 16 U.S. Environmental Protection Agency polycyclic aromatic hydrocarbons (PAHs) were measured in urban street dust with a view to understanding the potential risk to urban ...residents exposed to street dust, sources, and distribution of the PAHs. Gas chromatography–mass spectrometry was used to measure the concentrations of the PAHs after ultra-sonication with hexane/dichloromethane and clean up. The total concentrations of the Ʃ16 PAHs in the urban street dust from Warri and its environs ranged from 165.1 to 1012 µg kg ⁻¹. The isomeric ratios and the PCA indicated that combustion of petroleum and biomass are the major sources of PAHs in Warri and its environs. The total BaP carcinogenic and mutagenic potency concentrations (ƩBaP TEQ and ƩBaP MEQ) were in the range of 0.03 to 219 µg kg ⁻¹ and 0.52 to 182 µg kg ⁻¹, respectively. The incremental life cancer risk from exposure of the residents of Warri and its environs ranged from 4.07 × 10 ⁻⁷ to 3.11 × 10 ⁻³ and 2.13 × 10 ⁻⁷ to 1.49 × 10 ⁻³ for the children and adults, respectively, which were higher than the baseline value of acceptable risk of 10 ⁻⁶ (i.e ., one case per million people).
