A Survey of Concentrations and Source Characterization of Polycyclic Aromatic Hydrocarbons in Surface Waters of the Imiringi River System

Abstract

Ten water samples were collected along the Imiringi water channel, cutting across several sub-communities of the upstream to downstream sections of the river. All samples were collected in the month of August 2019, reflecting increased tidal movement of water and aggravated pollutants redistribution which is typical of the rainy season. Analysis was carried out using the HP 6890 Plus gas chromatograph – flame ionization detector (GC-FID). The rate of ionization of each PAH component was directly proportional to the obtained concentration. The total concentrations of 14 PAHs ranged from <0.01 to 300.1 µgL-1, with the high molecular mass PAHs (4-6 ring HPAHs) observed as the most important fractions showing 82.4% distribution. Also, the low molecular mass PAHs (2-3 ring LPAHs) were found in trace concentrations, accounting for 17.6% of total PAH mass. The application of PAH source diagnostic ratios revealed vegetation and coal combustion as primary sources, followed by petroleum combustion, and then, petroleum sources. Correlation cluster analysis (CCA) and principal component analysis (PCA) showed discrete localization for samples of stations OL1, OB2 and OS4. The pyrogenic inputs are most likely from runoffs of seasonally burnt vegetation at near-coastal farmlands as well as leachates from surrounding waste-dumpsites. Petroleum sources may have resulted from neighbouring oil installations and illegal oil bunkering sites. Overall, the study is aimed at identifying the most important contributing sources of polycyclic aromatic hydrocarbon (PAH) micro-pollutants in the aquatic environment.

Determination of sources, spatial variability, and concentration of polycyclic aromatic hydrocarbons in surface water and sediment of Imiringi River

“…In addition, the high level of HPAHs (Benzo(b)fluoranthene and Dibenz(a,h)anthracene) is solely an indication of biomass combustion (Figure 2). A spatial variability trend similar to the current study was reported for surface water samples collected from Imiringi River [21]. Also, due to oil bunkering activities along the Azuabie creek, the affected water ways recorded outlier concentrations of hydrocarbons (TPH and PAHs) as compared to control location.…”

“…Also, the Oswan-4 sample site depicted anthracene (0.30012 mg/L) with the highest concentration, while chrysene (0.00041 mg/L) reflected the least concentration. In the same vein, Aigberua [21] had recorded relatively higher concentrations of high molecular weight PAH fractions.…”

“…Apart from the unidentified PAH compounds, all other observed PAHs had concentrations exceeding the maximum allowable concentration (0.0002 mg/L) as given by Agency for Toxic Substance and Disease Regulation (ATSDR). Similarly, Aigberua [21] had reported the prevalence of high molecular weight PAHs (4-6 ring PAHs) in surface waters of Imiringi River. In the same vein, Yang et al [22] had reported the prevalence of 4 to 6 ring PAHs in suspended particulate dust around the Niger Delta region.…”

“…These fractions may have been lost due to environmental attenuation factors such as elevated temperature, low humidity, and tidal nature of the river, amongst others. Aigberua [21] had reported loss in light molecular weight PAHs in surface waters of the Imiringi River.…”

Polycyclic Aromatic Hydrocarbons: Evaluation of concentrations in environmental media in Bayelsa State

“…Environmental monitoring of the PAH levels of the water, soil, and fish was done and PAH levels were determined using the gas chromatography/flame ionization detector (GC/FID) method as described by Aigberua. 22 PAHs diagnostic ratios were used as a tool for the identification of the emission sources of the PAHs in the different environmental media. [23][24][25] Water samples were collected from five points in each study community using previously cleaned 1-L capacity glass bottles.…”