Lecturer, Industrial Chemistry, Elele Campus.
The concentrations of polychlorinated biphenyls (PCBs) in sediment samples from the New Calabar River in the Niger Delta Region of Nigeria were determined. Grab sediment samples were collected from five stations in the river and analyzed for individual PCB congeners using gas chromatography – mass spectrometer. The Σ8PCB (sum of eight congeners) identified in the samples ranged from 0.21 to 2.16 mg/kg. Congener 105 and 194 were the most and least abundant with 34.65 % and 2.46 % respectively. The lower chlorinated congeners (below PCB 101) were prominent with 54.68 % of the total PCBs concentration in the sediments. The results of this study should make PCBs contaminants of grave concern in the Niger Delta Region.
The composition of polycyclic aromatic hydrocarbons (PAHs) in soils within the vicinities of hot mix asphalt (HMA) production plants in Port Harcourt, Nigeria, was investigated. Soil samples were collected at an increasing distance of 10 m from two HMA plants, at surface (0-15 cm) and subsurface (15-30 cm) depths during dry and wet seasons. PAHs distribution in the soil samples were analyzed with gas chromatography equipped with flame ionization detector (GC-FID). PAHs concentrations during the dry season for HMA plant A ranged from 8.20 – 449.00 mg/kg and 5.66 – 271.00 mg/kg for surface and subsurface soils respectively. The concentrations in HMA plant B ranged from 219.00 – 378.00 mg/kg and 27.00 – 264.00 mg/kg for surface and subsurface soils respectively. The PAHs concentration in the wet season for HMA plant A ranged from 10.30 – 71.90 mg/kg and 4.11 – 38.50 mg/kg for surface and subsurface soils respectively while that of HMA plant B was between 28.70 – 106.00 mg/kg and 8.73 – 37.00 mg/kg for surface and subsurface soils respectively. PAH diagnostic ratios of Anthracene/Phenanthrene, Fluoranthene/Pyrene and Benzo[a]Anthracene/Chrysene indicated the dominant sources of PAHs within the HMA plant vicinities were pyrogenic with variable input from petrogenic sources due to petroleum fuels and oils from vehicle traffics, vehicle repair/maintenance in the plant area and runoffs during the wet season. Multivariate analysis of PAHs diagnostic ratios showed significant correlation (³ 72.04%) in soil samples from both HMA plant vicinities and revealed similar PAHs profiles dominated by pyrogenic PAHs.
This study characterised the polycyclic aromatic hydrocarbons (PAHs) in five road paving asphalt samples randomly collected from two hot mix asphalt (HMA) plants in Port Harcourt, Nigeria. The ∑16PAHs of the samples ranged from 103.79 mg/kg – 190.93 mg/kg. Naphthalene, Acenaphthylene, fluorene and benzo(g,h,i )perylene were not detected in any of the samples. The characteristic isomer ratios of the asphalt samples were also calculated to serve as a reference for road runoffs and leachates studies.
Hydrocarbon utilizing bacteria (HUB) were characterized in soils within a hot mix asphalt
(HMA) plant vicinity to ascertain their ability to thrive in such an environment. Soil samples
were collected at both topsoil (0-15 cm) and subsoil (15-30 cm) at an increasing distance of
10m from the HMA plant. The physico-chemical parameters and the n-alkane concentration
of the soil samples were determined using standard analytical methods. The results showed
the dominance of Micrococcus sp, Bacillus sp, Pseudomonas sp, Vibrio sp and
Flavobacterium sp among the isolated HUB. The pH of the soil samples were slightly acidic
while the conductivity was between 71.78±1.33 – 97.33±0.03 µS/cm. Total organic carbon
(TOC) and nitrate-nitrogen (NO3-N) were low at <10% and <0.5 mg/kg respectively. The nalkane concentration of the soil samples ranged from 8.69 – 65.08 mg/kg. This study enriches the dossier on bacterial diversity and it is expected that organisms that thrive in soils within HMA plant vicinity could be exploited for bioremediation purposes.