Distribution Trends and Source Diagnosis of Polycyclic Aromatic Hydrocarbons (PAHs) in Sediments of Imiringi River

Abstract

The environmental menace caused by hydrocarbon releasing activities on water bodies have remained a cause for great concern. Such activities are accompanied by the release of highly toxic and carcinogenic polycyclic aromatic hydrocarbons (PAH), which are easily biomagnified across the food chain, ultimately aggravating adverse health conditions in human. This study was aimed at identifying the most important environmental contributors of PAHs in sediments of the Imiringi river. Owing to the activities of oil facilities among other anthropogenic influences, water bodies are inundated with hydrocarbon pollutants which settle within river bed sediments, thereby, playing an important role in the redistribution of contaminants. The applied diagnostic ratios (Phenanthrene/Anthracene, Fluorene/Fluorene + Pyrene, Fluoranthene/Fluoranthene + Pyrene, pyrogenic index and total index) revealed the presence of mixed source of PAHs (pyrogenic and petrogenic). PAH concentrations ranged from <0.01 to 3,965.4 µg/kg with most detected compounds exceeding regulatory limits. The high molecular mass PAHs (4 - 6 ring HPAHs) represents the primary source showing 94.29% distribution, while the low molecular mass PAHs (2 - 3 ring LPAHs) recorded trace concentrations of about 5.71% of total PAHs. Principal component analysis (PCA) revealed Indeno(1,2,3-cd)pyrene and Dibenz(a,h)anthracene as principal PAH components in the environment. In addition, Pearson correlation showed Benzo(k)fluoranthene and Benzo(b)fluoranthene as the most positively correlating PAH species in sediment. Overall, the midstream section of the river was relatively more polluted than the up and down-river locations. Most notably, HPAHs recorded higher concentrations than the LPAHs. This may be due to intensive agricultural practices such as bush incineration, while waste dumps along the river bank remain tangible pyrogenic PAH contributors. On the other hand, trace amounts of observed petrogenic PAHs in some locations are possibly spill-over’s from oil bunkering activities and infiltrations from nearby oil installations.

Source Apportionment and Health Risk of Some Organic Contaminants in Water and Suspended Particulate Matter from Imo River, Nigeria

“…PCA source allocation of PAHs in SPM is shown in Table 6. and Seiyaboh, 2021). The toxicity of benzo (a)pyrene related to PAHs in SPM and water are presented in Table 7.…”

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

“…The extraction method that has been previously applied was adopted in this study. 29 They were air-dried at room temperature, crushed, and sieved through a 2 mm mesh sieve. Five grams of the well-homogenized sample was weighed, and this was transferred into 50 mL glass vials with Teflon crimp caps.…”

“…Others include setting the detector temperature at 310°C, nitrogen flow amount of 30 mL/min, hydrogen flow amount of 35 mL/min, and an airflow rate of 250 mL/min. 29…”

“…Results were expressed in concentration units of μg/kg. 29 Another 5 g portion of the soil was ceded into a 50 mL glass vial with Teflon crimp caps. It was spiked with predeuterated PAH internal standards mix (naphthalene-d8, phenanthrene-d10, chrysene-d12 and perylene-d12).…”

“…Others include setting the detector temperature at 310°C, nitrogen flow amount of 30 mL/min, hydrogen flow amount of 35 mL/min, and an airflow rate of 250 mL/min. 29 Extraction and quantification of PAHs from fish samples Fresh fish samples were cleaned using distilled water to get rid of dirt and the tissues were dissected and cut up into smaller pieces, after which a sub-sample was taken from the homogenate. The blending of the samples was then done, and the blended components were kept in airtight containers before the extraction process.…”