Petroleum and PAH contamination of the Black Sea

Concern has been expressed regarding the extent of contamination of the Black Sea. Analyses of coastal sediments taken from throughout the region indicate, however, that levels of petroleum hydrocarbons (2-300 microg g(-1) dry wt total hydrocarbons) are generally comparable to those encountered in the Mediterranean and are lower than concentrations reported for highly contaminated areas such as the Gulf, Hong Kong, Taiwan and New York Bight. Highest concentrations of total hydrocarbons (>100 microg g(-1) dry wt) were associated with discharges from Odessa, Sochi and the River Danube. Chronic/degraded petroleum was the major contributor at these sites. Samples from the Ukrainian coastline were comparatively clean (<10 microg g(-1) dry wt total hydrocarbons). Major contributions of fresh oil (as indicated by sigma n-C14-34) occur through the River Danube. Concerning total PAH, concentrations (7-638 ng g(-1) dry wt) compare to relatively unpolluted locations in the Mediterranean and are much lower than levels reported for polluted UK estuaries (e.g. Mersey, Tyne, Thames). Both pyrolytic and petrogenic PAH are present in most samples, although petroleum derived PAH are dominant at Sochi and pyrolytic sources are prevalent in the Bosphorus region. The absence of a correlation between total hydrocarbons and PAH (R2 = 0.04) indicates different primary sources for the two.     

Polycyclic aromatic hydrocarbons in the sediments of the Yalujiang Estuary,North China

Selected polycyclic aromatic hydrocarbons (PAHs) in surface sediments of the Yalujiang Estuary, North China, have been investigated by gas chromatography-mass spectrometry (GC-MS) for flood season (August, 1994) and dry season (May, 1996), respectively. PAHs concentrations from sediments range from 68 to 1500 ngg(-1) depending upon the sample locations. The most contaminated sediment samples are found in the turbidity maximum area for both dry and flood seasons. The source of PAHs is most likely pyrolytic, with minor contributions from petrogenic and diagenetic PAHs for some samples. Perylene is mainly derived from biogenic inputs, and occurs at almost stations. In the Yalujiang Estuary, both biogenic and anthropogenic hydrocarbons are primarily derived form riverine discharges and are accumulated in the mixing zone. The overall levels of PAHs in this study are low compared to other regions and reveal moderate PAHs pollution in the Yalujiang Estuary.     

Evaluation of surface sediment contamination by polycyclic aromatic hydrocarbons in the "Saco do Laranjal" - (Patos Lagoon, Brazil)

This paper evaluates the concentration of Polyaromatic hydrocarbons - PAHs in the Estuarine area of the Patos Lagoon, more precisely in a local named "Saco do Laranjal" in Pelotas City (southern Brazil). The samples were collected in May 2008. The concentrations of 16 US-EPA priority polycyclic aromatic hydrocarbons (PAHs) were determined by gas chromatography with a mass spectrometry detector (GC/MS). The sum of PAHs concentration ranged from 7.3 to 92.8μgkg(-1) in dry weight. The positive correlation (Pearson test) between the total organic material (TOM) and the total PAH concentration (0.98) suggests that TOM plays an important role in controlling the PAHs levels in the sediments. According to the observed ratios of individual PAHs, the contamination in the studied area is originated, predominantly pyrolytic sources. The values found are considered under normal levels and indicates a not impacted area.     

Inputs and sources of hydrocarbons in sediments from Cienfuegos bay, Cuba

The spatial distribution of aliphatic and polycyclic aromatic hydrocarbons (PAHs) was investigated in sediments from the Cienfuegos bay. The highest anthropogenic hydrocarbon inputs were found near the city of Cienfuegos with an unresolved complex mixture (UCM) of aliphatic hydrocarbons and alkylated PAHs, indicative of petrogenic inputs. Parent PAHs, which are typical of high-temperature combustion processes, were evenly distributed in the whole basin and largely prevailing in the southern part of the Cienfuegos city. Biomarker fingerprints assign the sources of pollution to mixes of national and non-national crude oils. The overall levels of anthropogenic hydrocarbons are relatively high compared to relevant areas worldwide and reveal a moderate/high level of hydrocarbon pollution. The Cienfuegos bay sediments received over a period of 5 yr, 50 T/yr of petrogenic unresolved hydrocarbons (UCM) and 2 T/yr of PAHs, being deposited the 80% in the sediments of the north basin.     

Sources and distribution of aliphatic and polyaromatic hydrocarbons in sediments of Jiaozhou Bay, Qingdao, China

The composition and distribution of aliphatic (n-alkanes) and polyaromatic hydrocarbons (PAHs) were measured for the surface sediments collected at 25 sites from Jiaozhou Bay, Qingdao, China. Total n-alkanes and PAH concentrations ranged from 0.5 to 8.2 microg/gdw and 0.02 to 2.2 microg/gdw, respectively, and the distribution of both n-alkanes and PAHs showed large spatial variations in the bay. The distribution of PAHs in the sediments was predominated by the three or more ring compounds. High hydrocarbon levels were generally found in the areas associated with high anthropogenic impact and port activities in the bay. The calculated hydrocarbon indexes suggest that petroleum contamination was the main source of n-alkanes, while both pyrolytic and petrogenic sources contributed PAHs to the surface sediments of Jiaozhou Bay. In comparison to other polluted coastal sediments, the level of contamination from both aliphatic hydrocarbons and PAHs in Jiaozhou Bay sediments is relatively low at the present time.     

Aliphatic and aromatic hydrocarbons in coastal Caspian Sea sediments

This investigation represents the first extensive study of the spatial distribution and sources of aliphatic (n-alkanes and unresolved complex mixture of fossil hydrocarbons) and polycyclic aromatic hydrocarbons (PAHs) in coastal sediments from the Caspian Sea. PAH concentrations, n-alkanes and biomarker profiles all suggested that there was limited petrogenic contamination in the shallow North Caspian Sea sediments, which are coarse with a low total organic carbon content. In contrast, moderate to high petrogenic contamination was found in the South Caspian Sea, in particular in the offshore oil fields near Baku, Azerbaijan. Contaminant patterns indicated that the PAHs were mainly from fossil sources, with higher contributions of pyrolytic only near industrialized and urban areas. A high contribution of perylene, a geochemically derived PAH, to the total PAHs was found in the west and south at sites influenced by the Kura, Safid Rud, Terek, Sulak and Samur Rivers.     

The 1974 spill of the Bouchard 65 oil barge: petroleum hydrocarbons persist in Winsor Cove salt marsh sediments

Petroleum hydrocarbons persist in salt marsh sediments in Winsor Cove (Buzzards Bay, Massachusetts) impacted from the 1974 spill of No. 2 fuel oil by the barge Bouchard 65. Intertidal sediment cores were collected from 2001 to 2005 and analyzed for total petroleum hydrocarbons (TPHs). TPHs content was greatest (as high as 8.7 mg g(-1) dry weight) in the surface sediments and decreased with distance landward. Select samples were analyzed for polycyclic aromatic hydrocarbons (PAHs) with values as high as 16.7 microg g(-1) for total naphthalenes and phenanthrenes/anthracenes. These remaining PAHs are mainly C(4)-naphthalenes and C(1)-, C(2)-, and C(3)-phenanthrenes/anthracenes revealing preferential loss of almost all of the naphthalenes and the parent compound phenanthrene. Inspection of the data indicates that biodegradation, water-washing and evaporation were major removal processes for many of the petroleum hydrocarbons in the marsh sediments. In addition, historical data and photographs combined with their recent counterparts indicate that erosion has physically removed these contaminants from this site.     

Spatio-temporal distribution and characteristics of PAHs in sediments from Masan Bay, Korea

The distribution of polycyclic aromatic hydrocarbons (PAHs) has been investigated in the surface and core sediments from Masan Bay, Korea. Total PAHs in the surface sediments ranged from 207 to 2670 ng/g dry weight with a mean value of 680 ng/g. Qualitative similarity and quantitative difference between inner and outer bay indicate that the main sources of PAHs are located in the inner bay and outer bay is also affected by the same sources. Vertical distribution of PAHs revealed that three distinctive stages could be differentiated with the help of PCA analysis. The highest concentration (industrialization stage) appeared between late 1950s and 1980, which was 10 years later than other developed countries. A strong pyrolytic source fingerprint has been detected with slight influence of petrogenic sources, and diagenetic PAH, perylene also contributed. Total organic carbon normalized PAHs (sum of 13 PAHs, 8.85-88.0 microg/g OC) were under the threshold effects concentration (TEC, 290 microg/g OC).     

Carbon speciation and composition of natural microbial communities in polluted and pristine sediments of the Eastern Mediterranean Sea

Sediment samples collected from polluted (Augusta Bay) and pristine regions of the Eastern Mediterranean Sea (South Ionian Sea, Thracian Sea) were analyzed for black carbon, aliphatic hydrocarbons and phospholipid ester-linked fatty acids (PLFA). The aim of the study was to investigate the anthropogenic and biogenic inputs into the Eastern Mediterranean Sea and to evaluate the effects of refractory organic matter (e.g. black carbon) and the level of hydrocarbon contamination on benthic microbial community composition. Black carbon, generally considered to be chemically and biologically inert, comprised a significant but highly variable fraction of the sedimentary carbon pool in the analyzed sediments with a ratio to total organic carbon ranging from 0.02 to 0.66. Principal component analysis of the chemical characteristics of the sediments (organic carbon content, black carbon, bioavailable organic carbon, chlorophyll a, phaeopigments, aliphatic hydrocarbons) revealed clustering of samples along a gradient from the most productive and contaminated region of Augusta Bay to the carbon-poor and pristine sediments of the Thracian Sea. PLFA analysis revealed that gram-negative bacteria and microeukaryotes were most abundant in Augusta Bay and in the most impacted station of the Thracian Sea. The high levels of branched and odd-chain fatty acids recorded for these stations is probably linked to the elevated amounts of hydrocarbons at these stations; e.g. microbial communities may have developed the ability to degrade either naturally occurring aliphatic hydrocarbons or hydrocarbons derived from oil contamination.     

Nature, distribution and origin of polycyclic aromatic hydrocarbons (PAHs) in the sediments of Olbia harbor (Northern Sardinia, Italy)

The nature, origin and distribution of US EPA polycyclic aromatic hydrocarbons (PAHs) in the sediments of Olbia harbor (North Sardinia, Italy) were investigated by gas-chromatography/mass spectrometry (GCMS). PAH concentrations in the sediments (SigmaPAHs) ranged from 0.16 to 0.77 microg g(-1), indicating a homogeneously low level of pollution. A rather exceptional prevalence of low molecular weight PAHs was substantiated: nearly 80% of SigmaPAHs include naphthalene (15.19%) and phenanthrene (64.47%). Carcinogenic compounds were present in very low (BaP, BkF, BaA and DBA) or negligible (BbF and Inp) concentrations. As indicated by the Phen/Ant molar ratio, the main source of PAHs is petrogenic, probably due to oil spills from shipping. The low/high molecular weight ratio (ranging between 1.2 and 26) distinguishes the sediments of the tourist harbor from those of the commercial/industrial harbor. Moreover, a slight but meaningful pyrolytic contribution to pollution was found in the tourist harbor, which has the most polluted sediments in the whole harbor. Finally, good linear correlations were found between a selected PAH (Phen and Naph) and selected sums of PAHs (i.e. the total amount of the other 15 US EPA and the sum of low molecular weight PAHs).     

Sources of organic matter in surface sediments of the Louisiana Continental margin: Effects of major depositional/transport pathways and Hurricane Ivan

Lignin and pigment biomarkers were analyzed in surface sediments of the Louisiana Continental margin (LCM) to distinguish differences in the degradative state of sedimentary organic matter along and between two major depositional pathways (along shore and offshore to the Mississippi Canyon) from Southwest (SW) Pass in July 2003. Barataria Bay, an inter-distributary estuary, was also assessed as a potential source of terrestrial organic matter to the LCM. Sediment signatures taken along the same pathways after Hurricane Ivan (October 2004) were compared with the pre-Ivan signature to elucidate carbon dynamics after major hurricane events. Density fractions were investigated at key stages across the LCM. Mississippi Canyon sediments are a depocenter for labile and refractory organic matter derived from river and previously deposited shelf sediments. Barataria Bay material may be a contributing source of sedimentary organic matter in shallow shelf areas bordering the bay and is thus potentially important in carbon cycling in sediments of these shallow areas; however, our results show that organic matter inputs from the bay were likely rapidly decomposed and/or diluted. Hurricane Ivan mobilized sedimentary organic carbon (SOC) offshore and homogenized terrestrial sediment parameters and gradients. As observed through pigment concentrations sediments tended to equilibrate to a more steady-state condition within months of the disturbance. Insights from density fractions show that selective degradation and aggregation/flocculation processes were also very important processes during cross-shelf transport. Zooplankton grazing, largely on diatoms and other algae, was a shelf wide phenomenon, however, grazing products dominated the marine-derived SOC in margin sediments west of the birdsfoot delta indicated by the abundance of steryl chlorin esters (SCEs).     

Composition and sources of organic matter and its solvent extractable components in surface sediments of a bay under serious anthropogenic influences: Daya Bay, China

Organic matter of nine surface sediments from the Daya Bay was Soxhlet-extracted with a mixture of 2:1 (v/v) dichloromethane-methanol and separated into five fractions: non-aromatic hydrocarbons, aromatic hydrocarbons, ketones, alcohols, and fatty acids and asphaltenes, and analyzed to determine their bulk and biomarker composition. Marine autogenic input appears to be a major source of organic matter. Generally, non-aromatic hydrocarbons are the most dominant fraction of solvent-extractable organic matter (EOM) followed by the other four fractions in decreasing amounts: fatty acids and asphaltenes, ketones, alcohols and aromatic hydrocarbons. On average, both non-aromatic hydrocarbon fraction and fatty acid and asphaltene fraction account for approximately 40% of EOM. The sources of acyclic methyl ketones, alkanols and fatty acids were examined. For n-alkan-2-ones, allochthonous input is a more important source than marine autogenetic input; the reverse is true for n-fatty acids; for n-alkanols, allochthonous and autogenetic inputs seem comparable. Both n-alkan-2-ones and n-fatty acids in the surface sediments of different areas appear to be derived from common sources.     

Using the N/C ratio to correct bulk radiocarbon ages from lake sediments: Insights from Chilean Patagonia

The offset between AMS radiocarbon ages obtained on bulk lake sediments and the true age of deposition was evaluated at four sites in Northern Chilean Patagonia. Our results show that the bulk radiocarbon ages are systematically older by 300 to 1100 years. In this region free of carbonate and carbonaceous rocks, we argue that this difference results from variable inputs of terrestrial organic carbon from the Holocene soils that cover the lake watersheds. For the four studied lakes, the age offset is clearly related to the fraction of terrestrial carbon preserved in the lake sediments, which was estimated using the N/C ratio of the bulk organic matter. We propose that N/C measurements can be used to significantly improve chronologies based on radiocarbon dating of bulk lake sediments.     

Distributions of polycyclic aromatic hydrocarbons in the Daliao River Estuary of Liaodong Bay, Bohai Sea (China)

The distributions of 16 polycyclic aromatic hydrocarbons (PAHs) were determined in the aqueous phase, suspended particulate matter (SPM), sediment, and pore water of the Daliao River Estuary in Liaodong Bay, Bohai Sea (China). Total PAH concentrations ranged from 139.16 to 1717.87 ng L⁻¹ in surface water, from 226.57 to 1404.85 ng L⁻¹ dry weight in SPM, from 276.26 to 1606.89 ng g⁻¹ dry weight in sediments, and from 10.20 to 47.27 μg L⁻¹ in pore water. PAH concentrations were at relatively moderate levels in water, SPM, sediment and pore water in comparison with those reported for other estuary and marine systems around the world. Sedimentary PAH concentrations decreased offshore owing to active deposition of laterally-transported river-borne particles. PCA analysis of the possible PAH source suggested petrogenic and pyrolytic PAH inputs in the studied region.     

Effects of algal turfs and sediment on coral settlement

Successful settlement and recruitment of corals is critical to the resilience of coral reefs. Given that many degraded reefs are dominated by benthic algae, recovery of coral populations after bleaching and other disturbances requires successful settlement amidst benthic algae. Algal turfs often accumulate sediments, sediments are known to inhibit coral settlement, and reefs with high inputs of terrestrial sediments are often dominated by turfs. We investigated the impacts of two algal turf assemblages, and of sediment deposits, on settlement of the coral Acropora millepora (Ehrenberg). Adding sediment reduced coral settlement, but the effects of different algal turfs varied. In one case, algal turfs inhibited coral settlement, whereas the other turf only inhibited settlement when combined with sediments. These results provide the first direct, experimental evidence of effects of filamentous algal turfs on coral settlement, the variability in those effects, and the potential combined effects of algal turfs and trapped sediments.     

Concentration,composition and sources of PAHs in the coastal sediments of the exclusive economic zone (EEZ) of Qatar,Arabian Gulf

Surface sediments were collected from sixteen locations in order to assess levels and sources of polycyclic aromatic hydrocarbons (PAHs) in sediments of Qatar exclusive economic zone (EEZ). Samples were analyzed for 16 parent PAHs, 18 alkyl homologs and for dibenzothiophenes. Total PAHs concentration (∑PAHs) ranged from 2.6 ng g⁻¹ to 1025 ng g⁻¹. The highest PAHs concentrations were in sediments in and adjacent to harbors. Alkylated PAHs predominated most of the sampling locations reaching up to 80% in offshore locations. Parent PAHs and parent high molecular weight PAHs dominated location adjacent to industrial activities and urban areas. The origin of PAHs sources to the sediments was elucidated using ternary plot, indices, and molecular ratios of specific compounds such as (Ant/Phe + Ant), (Flt/Flt + Pyr). PAHs inputs to most coastal sites consisted of mixture of petroleum and combustion derived sources. However, inputs to the offshore sediments were mainly of petroleum origin.     

Hydrocarbons in surface sediments from the Changjiang (Yangtze River) Estuary, East China Sea

Sedimentary aliphatic (AH) and polycyclic aromatic hydrocarbons (PAHs) were studied in the Changjiang Estuary and the adjacent East China Sea. Total AH ranged from 2.20 to 11.82 μg g⁻¹ and consisted of n-alkanes and a dominant petroleum-related unresolved complex mixture (UCM). Within the n-alkanes, terrestrial plant wax compounds prevailed at nearly all stations. Of the PAHs, biogenic perylene dominated at stations receiving riverine inputs. Anthropogenic PAHs originating from combustion/pyrolysis processes varied from 17 to 157 ng g⁻¹, while fossil PAH concentrations ranged from 42 to 187 ng g⁻¹. Both biogenic and anthropogenic hydrocarbons are primarily derived from riverine discharges and accumulate at shallow-water stations. Distinct phase associations lead, nevertheless, to different sedimentation patterns. Fossil PAHs are enhanced at offshore stations where they are introduced directly by shipping activities. Biomarker fingerprints ascribe their source to Chinese crude oils. The overall levels of anthropogenic hydrocarbons are low compared to relevant areas worldwide and reveal a low/moderate level of hydrocarbon pollution.     

Relationships between persistent organic pollutants and carbonaceous materials in aquatic sediments of Taiwan

Recent studies have shown that many persistent organic pollutants (POPs, e.g., polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and various pesticides), are strongly associated with carbonaceous materials (including organic carbon (OC) and black carbon (BC)). We hypothesize that carbonaceous materials can be used as a first-order pollution index, to indicate areas where POP pollution may require further investigation. We tested our hypothesis and found that strong, positive correlations between BC and OC contents versus the concentrations of PCBs (and PAHs) existed in estuarine sediments of the Danshui River in 2005 and 2008. Thus, our preliminary results demonstrate that POC and BC are potential indicators of the POP pollution potential in fluvial sediments of the Danshui River in Taiwan. This innovative approach can provide a simple, relatively inexpensive and expedient means to monitor concentrations of POPs in polluted aquatic sediments of Taiwan, and/or those having a legacy of POP inputs.     

Aliphatic and polyaromatic hydrocarbons in bottom sediments of offshore mouth area of the Volga

Data on the concentration and composition of aliphatic and polyaromatic hydrocarbons in the surface layer and the body of bottom sediments in Volga delta and on the northern Caspian shelf are given. Volga delta sediments are shown to contain large concentrations of organic compounds. It is established that the concentrations of organic compounds is largely dependent on the dispersiveness of sediments. Anthropogenic hydrocarbons, both oil and pyrogenic, fail to pass the marginal filter of the Volga River and do not reach the open part of the sea. Therefore, the hydrocarbons contained in the bottom sediments on the Caspian Sea shelf are mostly of natural genesis. The distribution of organic compounds in the bottom sediment strata has a complex character. In some cases, their concentration increases because of the higher flux of hydrocarbons (especially, polyarenes in the 1950s).     

Hydrocarbons in the modern sediments of the Caspian Sea

The presented results have been obtained in a study of the concentrations and composition of aliphatic and polycyclic hydrocarbons in bottom sediments of Volga delta branches and in its shallow zone (2009–2010), as well as the Caspian Sea proper (2010–2013). Oil hydrocarbon pollution has been found to manifest itself mostly in Volga delta branches, which, despite the low concentrations (up to 54.5 μg/g), showed higher hydrocarbons share in C_org (up to 33.8%), while the composition of alkanes suggested their oil genesis. The geochemical barrier the Volga–the Caspian Sea prevents anthropogenic hydrocarbons from entering the open parts of the Caspian. Bottom sediments in the shallow zone of the Northern Caspian, represented by coarse-grained material, are now polluted by oil hydrocarbons to a lesser extent compared with other areas. The highest concentrations of aliphatic hydrocarbons (up to 178 μg/g) were recorded in the deepsea bottom sediments of Derbent Depression and in depressions of the Middle and Southern Caspian. These areas show a higher concentration of C_org (up to 9.884%) and a low concentration of hydrocarbons in C_org (up to 0.16%), while odd high-molecular homologues (n-C₂₅–C₃₁) dominate in the composition of alkanes.