Determination of Aliphatic and Polycyclic Aromatic Hydrocarbons in Marine Core Sediments off Johor, Malaysia

Aliphatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) were studied in two sediment cores of southern South China Sea off Johor coastal area. The concentrations of the total identified resolved aliphatic hydrocarbons (TiRAHs) in the coastal station (STC104) ranged from 0.35 to 2.07 µg/g while the offshore station (STC100) varied from 0.05 to 14.7 µg/g. The concentrations of total PAHs were varied from not detected to 33.9 ng/g. The nalkanes distribution in STC104 were predominant in short chain carbons from marine productivity, petroleum mixture and minor higher plant input, while STC100 exhibited a bimodal distribution with mixed input of marine and terrestrial origin. PAHs isomer ratios cross-plot have showed mixed input of pyrogenic and petrogenic inputs while perylene was dominated in STC100 followed by fossil fuels and pyrogenic source. Presence of perylene in both cores suggesting the contribution of biogenic sources. Principal component analysis was used to cluster the relationship of the hydrocarbons at both sediment cores.

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

Polycyclic aromatic hydrocarbons (PAHs) are very toxic and persistent environmental micro-contaminants that possess health-impacting tendencies. Environmental levels of PAHs are mainly exacerbated by anthropogenic activities. At elevated concentrations, PAHs become toxic and readily bio-magnify across the food chain. This study was undertaken to determine the concentration and identify possible sources of PAHs in Imiringi River. PAH concentrations depicted the following ranges; Oswan-1 (0.00046 – 0.05010 mg/L and 0.00002 – 0.01812 mg/kg); Olem-1 (0.02428 - 2.86264 mg/L and 0.00151 - 3.96536 mg/kg); Oswan-4 (0.00041 - 0.30012 mg/L and 0.00143 - 0.04530 mg/kg) for water and sediment samples respectively. PAHs mostly exceeded the recommended maximum contaminant levels (MCL) stipulated by United States Environmental Protection Agency (USEPA), while high molecular weight PAHs (4 – 6 ring PAHs) are prevalent in the environment. The applied diagnostic ratio (fluoranthene/pyrene) values for surface waters at Oswan-1 (0.8364) and Olem-1 (0.7337), and sediment at Olem-1 (0.4894) were less than 1, thereby reflecting petrogenic PAHs (from gasoline and diesel). On the other hand, Fluoranthene/Pyrene ratio of sediments from Oswan-1 (2.4558), Oswan-4 (2.3565) and surface water at Oswan-4 (2.0252) depicted values greater than 1, indicating pyrogenic PAHs (from coal combustion). Results further showed Fluoranthene/(Fluoranthene + Pyrene) ratio for all sampling locations at values greater than 0.4 for both surface water and sediment. Hence, revealing pyrogenic source PAHs (from combustion of fossil fuel, coal, grass, wood, etc). Overall, the water body showed reasonable hydrocarbon contamination. As such, it is unsuitable for consumption, as well as recreational and agricultural activities. The application of One-way ANOVA statistics showed spatial variability (p < 0.05) for different PAH species across different sections of river, while principal component analysis (PCA) revealed discrete similarities for most PAHs, excluding anthracene and Dibenz(a,h)anthracene.

Bulk and molecular composition variations of gold-tube pyrolysates from severely biodegraded Athabasca bitumen

Gold-tube pyrolysis experiments were performed on two Athabasca oil sand bitumens at 300 °C to 525 °C with 2 °C/h rate and 25 °C step under 50 MPa. Pyrolysis temperature of 425 °C is critical for weight loss of bulk bitumen and hydrocarbon generation and destruction. Polar compounds are the main source of saturated and aromatic hydrocarbon, gas and coke fractions. Molecular compositions in pyrolyzates vary systematically with increasing pyrolysis temperatures. High molecular weight n-alkanes (C26+) are gradually destructed during pyrolysis due to thermal cracking. Moderate molecular weight n-alkanes (C21–C25) show the highest thermal stability in designed pyrolysis temperatures. The loss of low molecular weight n-alkanes (C20−) might be caused by volatilization during pyrolysis, which may alter commonly used molecular parameters such as ∑n-C20−/∑n-C21+, Pr/n-C17 and Ph/n-C18. Aromatic hydrocarbons were generated from 300 to 425 °C, then condensation and dealkylation have been initiated at 425 °C as evidenced by decreased summed alkylnaphthalenes to alkylphenanthrenes ratios and increased unsubstituted aromatics to substituted homologs ratios in higher temperatures. The occurrence of anthracene and benz[a]anthracene in pyrolysates indicates pyrogenic origin, while fluoranthene shows unexpected behaviors during pyrolysis. Ratios derived from them are not always reliable for pyrogenic source input diagnosis in environmental samples.

Levels of PAHs in shrimps, Penaeus monodon from Jones Creek southern Nigeria

Polycyclic aromatic hydrocarbons (PAHs) were measured in shrimp samples (Penaeus monodon) of Jones Creek southern Nigeria during the rainy and dry seasons and analysed for 16 priority PAHs. The ΣPAHs ranged from 0.073 to 0.800 mg/kg for shrimp samples collected for the 18 month duration of this study. Fluorene and anthracene were the most dominant PAH observed with concentrations of 0.084 ± 0.010 mg/kg and 0.059 ± 0.007 mg/kg respectively. Fluorene was also the most detected PAH comprising 21.91% of the 16 PAHs detected while benzo(g,h,i)perylene was the least with 0.02%. The source of contamination is closely related to human activities such as domestic and industrial discharges, refining activities and street runoff. High concentrations were recorded during the rainy season and during the first quarter of the year. The investigated samples were classified as minimally contaminated when compared with FDA levels of PAHs in shrimp samples. Distribution patterns showed that PAHs with 3 and 4 rings dominated confirming the pyrogenic source of the detected PAH. Diagnostic ratios such as phenanthrene/anthracene and benzo(a)anthracene/chrysene were achieved to evaluate the emission sources of PAHs. These ratios indicated a pyrolytic source of PAHs for sediments, as well as a pyrolytic or pyrogenic origin of the PAHs detected in the shrimp samples obtained within the study area.Key words: PAHs, sediment, shrimps, cancer risk, diagnostic ratio.

Distribution and characteristic of PAHs in sediments from the southwest Caspian Sea, Guilan Province, Iran

Contamination by polycyclic aromatic hydrocarbons (PAHs) in the southwest Caspian Sea was assessed by examination of 45 sediment samples, collected from the coasts of the Guilan Province in 2012 and analyzed for 29 PAHs. The concentrations of PAHs were in the range of 232.1–1,014 ng g−1 dry weight (mean 520 ± 246.4 ng g−1). The predominance of alkyl-substituted naphthalenes and phenanthrenes and the higher contributions of petrogenic compounds (NPD = 35.4–74.4%) compared to pyrogenic PAH compounds (COM = 18.1–47.4%) reveal a petrogenic source for PAHs with ubiquitous distribution in the study area. Offshore increase of total PAH concentrations was found to be correlated with increase of organic matter content of sediments, but no correlations with particle size fractions were found. The evaluation of ecotoxicological risk by sediment quality guidelines indicated that total PAH concentrations at all sites were below the effects range-low (ERL), but some individual petrogenic PAHs at some stations were significantly above their ERL and likely to adversely affect benthic biota. According to the diagnostic ratios used, most stations revealed the major source of the PAHs to be petrogenic, but some stations suggested a mixed petrogenic-pyrogenic source.