Hydrocarbons In Sediment Cores Research Articles

Ecological and health risks of polycyclic aromatic hydrocarbons in the sediment core of Phayao Lake, Thailand

Polycyclic aromatic hydrocarbons (PAHs) in sediment cores from Phayao Lake were investigated in terms of their concentration, distribution, and potential effects on the environment and human health. The concentration of Σ16PAHs ranged from 77.6 to 1251.1 ng g-1. Additionally, low molecular weight PAHs (two or three fused aromatic rings) were dominant, indicating that the main source of PAHs is the incomplete combustion of organic sources. The toxic equivalent quantities (TEQs) of 16 PAHs varied from 2.67 to 155.09 ng g-1, with an average of 38.29 ± 46.69 ng g-1. Furthermore, the TEQs of 9 known carcinogenic PAHs averaged 20.77 ± 30.63 ng g-1. B[a]P had the highest TEQ, followed by D[a,h]A and B[k]F, with values of 16.93 ± 25.49, 13.89 ± 15.37 and 2.12 ± 3.64, respectively. The RQ(NCs) of ∑PAHs (RQ∑PAHs(NCs)) ranged from 1.65 × 10-4 to 6.27 × 10-1 with an average value of 1.18 × 100 ± 1.52 × 100. Moreover, RQ(NCs) was less than 1 for individual PAHs, indicating a minor risk. However, RQ(MPCs) was less than 1 for individual PAHs, indicating a moderate risk. The results showed a significant incremental lifetime cancer risk (ILCR) from sediment-bound PAHs with dermal absorption, followed by ingestion and inhalation, as the prevalent route of exposure. The measured ILCR values of all PAHs were less than 10-6 for both adults and children, which were lower than the baseline value, indicating that each PAH poses a low risk of cancer to humans. This study provides information for control and preventive actions to limit future PAH pollution in Phayao Lake.

Unusual natural polycyclic aromatic hydrocarbons in sediment cores of an Amazon estuary.

Polycyclic aromatic hydrocarbons (PAHs) most likely derived from natural sources were observed in two sediment cores covering the last 100years in an Amazon estuarine region. A considerable change in the PAHs main source was observed in the 1960s. Before the 1960s, the sources of PAHs seem to be related to biogenic and/or early-diagenetic processes. Concentrations of perylene were higher before the 1960s and suggest that its primary source to the sediments in the Amazon region is linked to a short-term diagenetic transformation of their biogenic precursors. The natural formation of alkylated PAHs in sediments was linked to the methylation of the parental aromatic hydrocarbons due to sediment maturation processes and the dehydrogenation of sterols in the sediments. The relatively rapid reaction occurring in recent sediments of the Amazon region suggests the importance of the microbial community in the transformation of biogenic precursors to alkylated-PAHs in the sediments.

Concentrations and source identification of priority polycyclic aromatic hydrocarbons in sediment cores from south and northeast Thailand

In this study, the environmental fate of carcinogenic polycyclic aromatic hydrocarbons (PAHs) in tropical lake sediments and their potential sources have been discussed. 15 PAHs (i.e. ΣPAH) have been investigated in two lakes, namely Songkhla Lake (SKL) and Nong Han Kumphawapi Lake (NHL), which are located at the southern and north-eastern parts of Thailand, respectively. Since these two lakes are registered as important wetlands under the Ramsar convention (United Nations Educational, Scientific and Cultural Organization: UNESCO), the quantitative identification of potential contributors of PAHs is an inevitable analytical tool for launching an evidence-based policy. The ΣPAH concentrations observed in SKL and NHL sediments (n = 135) were in the range of 19.4–1,218 ng g−1 and 94.5–1,112 ng g−1, respectively. While the exponential decline of ΣPAH contents were detected in SKL sediments, NHL showed a trend of enhancing PAH contents with depth. The averaged benzo [a]pyrene (B [a]P) contents of surface sediments in both lakes were much below the value stipulated by the United States Environmental Protection Agency (US-EPA) guidelines for carcinogen risk assessment. Based on numerous multivariate statistical techniques coupled with source apportionment analysis, “biomass burning” and “anthropogenic activities” are two potential contributors of the PAHs detected in the study areas. To achieve the long-term conservation of nature with related ecosystem services and cultural values, it is therefore important to promote decision-making based on ecotoxicological studies of carcinogenic substances.

Spatial and temporal trends of polycyclic aromatic hydrocarbons in sediment cores of Brunei Bay, East Malaysia

The spatial and temporal distribution of polycyclic aromatic hydrocarbons (PAHs) in three sediment cores from Brunei Bay, Southern South China Sea was investigated. The total concentrations of 16 priority PAHs (∑PAH16) and their alkyl-substituted derivatives ranged from 10.4 to 376 ng g−1 and 30.7 to 2263 ng g−1, respectively. PAH biomarker diagnostic ratios and principal component analysis (PCA) combined with absolute principal component score (APCS) and multiple linear regression (MLR) were performed to apportion the source contribution. The results revealed mixed inputs of fuel combustion residues and uncombusted petrogenic products. The downcore PAH profile revealed that the highest peaks could be related to past human activities using biofuel and coal during the industrialization/agriculture revolution period. The 1,7/(2,6+1,7)-dimethylphenanthrene ratio also highlighted wood combustion during forest fire outbreaks, which appeared to coincide with the past climate events.

Occurrence, distribution and composition of aliphatic and polycyclic aromatic hydrocarbons in sediment cores from the Lower Fox River, Wisconsin, US.

The Lower Fox River is a 39 mile section which supports approximately 270,000 rural inhabitants across 18 counties, 303,000 metropolitan residents in Green Bay and Appleton, Wisconsin, and several large industrial complexes such as paper mills and power plants. This paper presents the distribution and concentrations of aliphatic (n-alkanes) and aromatic hydrocarbons (polycyclic aromatic hydrocarbons [PAHs]) as well as total organic carbon (TOC) in the Lower Fox River to identify the sources of hydrocarbon contamination. Excluding one outlier, percent TOC values were between 0.73 and 19.9% with an average value of 6.74%. Total n-alkanes ranged from 3.51μg/g to 117μg/g and showed a strong presence of odd carbon-numbered n-alkane ratios (range of C25 to C35), suggesting source input from terrestrial biomass. The mean polycyclic aromatic hydrocarbon (PAH) concentration was 24,800ng/g. High molecular weight PAH concentrations dominated the distribution of hydrocarbon contaminants. Cross-plots of PAHs were used to compare diagnostic source ratios of benz[a]anthracene (BaA), chrysene (Chr), fluoranthene (Flu), pyrene (Pyr), anthracene (Ant), phenanthrene (Phe), indeno[1,2,3-cd]pyrene (InP), and benzo[g,h,i]perylene (BghiP) by depth and area. PAH ratios varied slightly with the core depth. Deeper core sections indicated the presence of biomass combustion while the upper core sections indicated combustion of both petroleum and biomass. The PAH toxicity of one core was estimated using toxicity equivalency factors, and the benzo[a]pyrene toxic equivalence quotient totaled 2,293ng/g-dry wt. Levels of PAHs in sediments are compared with established regulatory values and recommendations are made.

Distribution and evolution of sterols and aliphatic hydrocarbons in dated marine sediment cores from the Cabo Frio upwelling region, SW Atlantic, Brazil.

We report the distribution of selected lipid biomarkers specifically sterols and aliphatic hydrocarbons in sediment cores from Cabo Frio, SW Atlantic continental shelf, Brazil, corresponding approximately to the last 700years. In the Cabo Frio region, a costal upwelling occurs as a quasi-seasonal phenomenon characterized by nutrient-rich bottom waters that intrude on the continental shelf and promote relatively high biological productivity compared to other Brazilian continental shelf areas. The results for sterols indicate the predominance of organic matter (OM) inputs related to marine organisms, mainly plankton, in all of the cores along the time scale studied. Principal component analyses show three different groups of variables, which may be associated with (i) the more effective intrusion of the nutrient-rich South Atlantic Central Water, resulting in the increase of marine lipid biomarkers such as sterols and short-chain n-alkanes; (ii) the influence of the Coastal Water with higher surface water temperature and subsequently lower primary productivity; and (iii) OM characterized by high total organic carbon and long-chain n-alkanes related to an allochthonous source. Relatively high concentrations of sterols and n-alkanes between 1450 and 1700AD, chronologically associated with the Little Ice Age, suggest a period associated with changes in the local input of specific sources of these compounds. The concentrations of lipid biomarkers vary over core depth, but this does not suggest a notably high or low intensity of upwelling processes. It is possible that the climatic and sea surface temperature changes reported in previous studies did not affect the input of the sedimentary lipid biomarkers analyzed here.

Polycyclic aromatic hydrocarbons in sediment cores from the Dashiwei Tiankeng reach in the Bailang underground river, South China

Sediment cores from the Dashiwei Tiankeng reach of the Bailang underground river were collected and analyzed for polycyclic aromatic hydrocarbons (PAHs). The concentrations of total PAHs ranged from 35.34 to 280.17 ng/g (mean 107.65 ng/g), and the concentrations of benzo[a]pyrene ranged from 1.78 to 175.74 ng/g (mean 35.94 ng/g). Analyses on molecular markers inferred that the PAHs were sourced mainly from wood and coal combustion before 1998, but there were obvious petroleum and petroleum combustion inputs after 1999. The PAHs profile indicated that the Bailang underground river was polluted by two major events. One was steel smelting in the 1950s, and the other was rapid economic development in the 1990s. The relationship between the PAHs and the sediment organic matter (SOM) in the profile was negative. Factors that impacted the SOM contents in sediment core included vegetation, agriculture crops, wood and fossil fuel burning, and soil erosion caused by construction. The sediment cores from the Bailang underground river reflected the economic development of the region.

Vertical profile, sources, and equivalent toxicity of polycyclic aromatic hydrocarbons in sediment cores from the river mouths of Kaohsiung Harbor, Taiwan

Six sediment cores collected at four contaminated river mouths and two harbor entrances in Kaohsiung Harbor (Taiwan) were analyzed to evaluate the sources and potential toxicity of polycyclic aromatic hydrocarbons (PAHs). PAHs presented the wide variations ranging from 369±656 to 33,772±14,378ngg−1 at the six sampling sites. The composition of PAHs presented a uniform profile reflecting the importance of atmospheric input from vehicle exhausts or coal combustion in the river mouths. PAHs diagnostic ratios indicated a stronger influence of coal combustion in the Salt River mouth and the prevalence of petroleum combustion and mixed sources in the other rivers and harbor entrances. PAHs toxicity assessment using the mean effect range-median quotient (m-ERM-q: 0.011–1.804), benzo[a]pyrene-toxicity equivalent (TEQcarc: 22–2819ngTEQg−1), and dioxin-toxicity equivalent (TEQfish: 37–5129pgTEQg−1) identified the Salt River mouth near the industrial area of the harbor as the most affected area.

Evaluation of anthropogenic inputs of hydrocarbons in sediment cores from a tropical Brazilian estuarine system

Sources and historical deposition of aliphatic and polycyclic aromatic hydrocarbons (PAHs) were investigated in sediment cores from the tropical Mundaú–Manguaba estuarine-lagoon system (MMELS), an important and representative ecosystem of Brazil. The MMELS has approximately 30% of its areas covered of sugar-cane monoculture. Anthropogenic inputs from sugar-cane processing and urban growth can pose environmental problems. The short cores from MMELS were collected in 2007 at four sites: Manguaba Lagoon (C03 and C09), Mundaú Lagoon (C07) and Mundaú River (C08). The analytical method was evaluated for n-alkanes and PAHs, the recoveries of the samples demonstrated good accuracy (mostly above 70% recovery) and precision (below 30%). The total aliphatic hydrocarbon (TAH) concentrations ranged from 27.8 to 139.5μgg−1. Only core C07 presented values above 100μgg−1, being considered contaminated by aliphatic hydrocarbon. The presence of the unresolved complex mixture (UCM), hopanes and steranes indicated petrogenic contribution. The characteristics of n-alkanes based on the terrigenous/aquatic ratio (TAR), carbon preference index (CPI) and average chain lengths (ACL) showed that the terrigenous input was predominant. The Σ16PAH concentrations ranged from 29.2 to 222.7ngg−1, and thus the sediments are considered slightly polluted. The abundance of perylene compared to other PAHs can be used as an indicator of natural origin of this compound. The MMELS cores showed concentrations of perylene greater than 10% of the total penta-aromatic isomers, indicating natural contribution of this compound. The lowest values of Σ16PAH and perylene were found for core C07, nevertheless the higher values of TAH, UCM, hopanes and steranes were observed. The PAH isomeric ratios reflected a pattern of mainly pyrogenic input (petroleum, coal and biomass combustion). The potential ecosystem risk assessment indicated for PAHs is considered relatively low in MMELS. Despite the industry and the sugar-cane monoculture, the system did not show elevated or alarming data.

Variations and Origins of Aliphatic Hydrocarbons in Sediment Cores from Chini Lake in Peninsular Malaysia

Over the past decade, Chini Lake has experienced tremendous changes due to land conversions from forest to agriculture such as oil palm and rubber plantations and also construction of a small barrage downstream of the Chini River. This land conversion has caused changes to the plant community and increased sedimentation rates in the lake. Consequently, this study was carried out to investigate the distribution patterns and sources of n-alkanes in four sediment core samples from Chini Lake and to evaluate the relative changes in organic matter inputs from land and lake flora. In the long-chain n-alkanes (LHC > C23)region, carbon preference index (CPI) values ranged from 1–1.52 in the sediment cores. Most lake sediments analyzed did not contain an unresolved complex mixture (UCM). The average nC17/pristane ratios (nC17/Pr) were 5.34 ± 1.99 and the average nC18/phytane (nC18/Ph) ratios were 1.27 ± 0.25 for the sediment profiles. The n-alkane average chain length (ACL) was 29.68 ± 0.15in the study area. There was significant positive correlation between ACL and CPI in the sediment cores at station B (r = 0.769, p = 0.003), station C (r = 0.735, p = 0.015), station D (r = 0.737, p = 0.006), and station E (r = 0.741, p = 0.006). Positive correlations between diploptene and long-chain n-alkanes (nC25−nC33) were found for sediment core B (r = 0.976, p<0.001), sediment core C (r = 0.836, p = 0.003), sediment core D (r = 0.824, p = 0.001) and sediment core E (r = 0.865, p < 0.001). Terrigenious to aquatic ratio for hydrocarbons (TARHC) and total n-alkanes (∑HC) concentrations increased with depth a pattern that contrast with short chain n-alkanes/total organic carbon (SHC/TOC) ratios. It can be concluded that the petrogenic hydrocarbon contamination in the sediment cores is minimal and that the n-alkanes preserved in Chini Lake sediments are influenced by higher plant waxes and bacteria.

Fingerprinting Analysis and Characterization of Hydrocarbons in Sediment Cores from the Pearl River Estuary, China

The Pearl River Delta (PRD) in southern China has undergone rapid urbanization and industrialization over the past few decades, leading to a substantial accumulation of hazardous organic compounds and a significant environmental impact. Forensic analysis of estuarine sediments is critical in order to uncover the contamination history and evaluate the level of contamination of the aquatic system and its ambient regions. A number of hydrocarbons and hydrocarbon groups including polycyclic aromatic hydrocarbons (PAHs), biomarkers, and diamondoids were found in representative sediment cores collected in the Pearl River Estuary (PRE) with average values determined to be 1,300, 288, and 5.85 ng/g dry weight in core #1 (inner shelf) and 283, 26.8, and 2.06 ng/g dry weight in core #2 (outer shelf), respectively. The results clearly suggest that the contamination in PRE sediment was derived from various inputs including petrogenic, biogenic, and pyrogenic sources. Because diamondoids are naturally absent from modern sediments that are free from petroleum contamination, in addition to the signatures of determined alkylated PAHs and biomarker terpanes and steranes, the presence of trace diamondoid compounds provides further evidence of petroleum contamination in the offshore and coastal areas of the PRE.

Distribution of trace metals, aliphatic hydrocarbons and polycyclic aromatic hydrocarbons in sediment cores from the Sicily Channel and the Gulf of Tunis (south‐western Mediterranean Sea)

Under the framework of the IAEA's Technical Co‐operation project RAF7/004, international research cruises were carried out in 2004 to assess the distribution of radionuclides and micropollutants in the south‐western Mediterranean Sea. Sediments samples had variable concentrations of total aliphatic hydrocarbons and polycyclic aromatic hydrocarbons ranging from 0.2 to 1.8 µg g−1 and 26.9 to 364.4 ng g−1, respectively, in the Sicily Channel and from 0.7 to 2.8 µg g−1 and 14.7 to 618.1 ng g−1, respectively, in the open sea of the Gulf of Tunis. Hydrocarbon concentrations changed with depth and were relatively high at 3 cm and 10 cm depths. The use of ‘fingerprint’ ratios of certain isomeric pairs of polycyclic aromatic hydrocarbons (PAH) and the proportion of 2–3 ring and 4–5 ring PAH concentrations showed that the main origins are characteristic of petroleum sources. The ranges of trace metal concentrations, expressed in µgg−1, in the Sicily Channel and in the Gulf of Tunis, respectively, were: Hg 0.009–0.2 and 0.02–0.1; Pb 9.9–26.1 and 21.2–32.5; Cd 0.06–0.1 and 0.07–0.33; Fe 23.7–28.1 and 29.9–36.2p; Zn 83–99.5 and 83–104; Mn 309.2–752.5 and 651–814; Cu 17.1–18.5 and 33.5–51.3. Sediment metal abundances were in the order: Mn > Zn > Fe > Cu > Pb > Cd > Hg. The results showed significant differences (p < 0.001) for trace metal and hydrocarbon mean concentrations between the two cores. These concentrations are generally similar to the background levels from the Mediterranean Sea and could be affected by physico‐chemical conditions and sedimentation rate as well as biodegradation.

Temporal trends of hydrocarbons in sediment cores from the Pearl River Estuary and the northern South China Sea

Concentrations and fluxes of unresolved complex mixture of hydrocarbons (UCM) and polycyclic aromatic hydrocarbons (PAHs) were analyzed for two (210)Pb dated sediment cores from the Pearl River Estuary (PRE) and the adjacent northern South China Sea (NSCS). Compound-specific stable carbon isotopic compositions of individual n-alkanes were also measured for identification of the hydrocarbon sources. The historical records of PAHs in the NSCS reflected the economic development in the Pearl River Delta during the 20th century. PAHs in the NSCS predominantly derive from combustion of coal and biomass, whereas PAHs in the PRE are a mixture of petrogenic and pyrogenic in origins. The isotopic profiles reveal that the petrogenic hydrocarbons in the PRE originate predominantly from local spillage/leakage of lube oil and crude oils. The accumulation rates of pyrogenic PAHs have significantly increased, whereas UCM accumulation has slightly declined in the NSCS in the recent three decades.

Hydrocarbons in age-dated sediment cores from two basins in the Southern California Bight

The distributions of hydrocarbons in sediment cores dated by 210Pb (1845–1977) from San Pedro and San Nicolas Basins in the Southern California Bight have been determined by gas Chromatographic and combined gas chromatographic-mass spectrometric analysis. The chromatograms of the hydrocarbons contain peaks of resolved alkanes and cycloalkanes, as well as an unresolved complex mixture which decrease in content with increasing depth in both of the cores. The concentrations of o,p' and p,p'-DDE are highest in the top 50 mm of the San Pedro core section. The 45–50 mm segment of this core was deposited in the 1945–1950 period when DDT (the precursor of DDE compounds) came into common use. The relatively high content of hydrocarbons and DDE in this core is attributable to the proximity of the site to the San Pedro Harbor which receives petroleum residues from shipping, sewage outfalls and industrial effluents. The presence of only traces of DDE throughout the San Nicolas core, and the low hydrocarbon content are explainable by the greater distance of this basin from anthropogenic inputs and probably a greater rate of degradation of deposited organic matter during bioturbation. δ 13C, δ 15N and electron-spin resonance analyses of kerogens and humic substances in these cores, indicate that most of this organic matter in these sediments is of a marine origin.