Distribution and characteristics of PAHs in sediments from the Mediterranean coastal environment of Egypt

To assess the contamination of polycyclic aromatic hydrocarbons (PAHs) in the Mediterranean coastal environment of Egypt, 26 sediment samples from the coastline, harbours, estuaries and coastal lakes were collected and analyzed. The sediment PAH concentrations of thirty-nine 2-6 ring PAHs ranged from 13.5 to 22,600 ng/g. PAH profiles varied according to the nature of the site and its proximity to sources. Industrialized and urbanized region showed high level of PAHs contamination. In general, the contamination levels of PAHs were similar to those observed in contaminated and slightly contaminated sediments of the Mediterranean Sea. Molecular indices based on ratios of selected PAH concentrations were used to differentiate PAHs from pyrogenic and petrogenic and mixed origins. Good correlations were observed between the petrogenic index, MP/P, A-PAHs/P-PAHs and HMW/LMW. Finally, PAH levels in sediments were compared with Sediments Quality Guidelines (ERM-ERL) for evaluation of probable toxic effects on organism.     

PAH contamination of western Irish Sea sediments

Concentrations of the sum of 15 PAHs in 22 surficial sediment samples from the western Irish Sea ranged from below 100 ng g⁻¹ in sandy sediments to a maximum of 1422 ng g⁻¹ in the centre of the mud basin. The concentrations are typical of coastal shelf sediments, but greater than those observed for aquatic sediments remote from known anthropogenic sources. Organic C and the % sediment <15 μm were positively correlated with ΣPAH. ΣPAH was normalised to organic C and particle size (i.e. expressed as ΣPAH/C^org and ΣPAH/%<15 μm) and significant relationships were still observed with organic C and %<15 μm. The results are discussed in the context of using organic C to normalise concentrations of PAHs to assess contamination levels in sediments.     

Occurrence and phase distribution of polycyclic aromatic hydrocarbons in riverine runoff of the Pearl River Delta,China

The occurrence and phase distribution of polycyclic aromatic hydrocarbons (PAHs) in waters at the eight riverine outlets of the Pearl River Delta (China) were examined based on a monthly sampling program from March 2005 to February 2006. The total concentrations of PAHs in the aqueous phase and suspended particulate matter (SPM) combined ranged from 55.5 to 522 ng/L, at the mid level of the global values in rivers and estuaries. No clear temporal and spatial trends of PAH concentrations were found. However, the concentrations of PAHs associated with SPM coincided with the monthly precipitation of Guangzhou, indicating the importance of atmospheric deposition. The PAHs found in the region were likely derived from a combined pyrolytic and petrogenic origin, as suggested by the molecular indices of PAHs. Normalized partition coefficient (K_oc) between water and SPM was correlated with octanol–water partition coefficient (K_ow) to understand the environmental behavior of PAHs.     

Composition, distribution and sources of polycyclic aromatic hydrocarbons in sediments of the Gulf of Trieste, Northern Adriatic Sea

The composition, distribution and the sources of polycyclic aromatic hydrocarbons (PAHs) in the surficial sediments of the Gulf of Trieste were investigated. To document the spatial PAH input, surficial sediment samples from 17 locations throughout the Gulf were analysed. The total PAH load determined in the surficial sediment samples are between 30 and 600 ng g-1, and were the highest in the immediate vicinity of the Port of Trieste. The PAH contents decline rapidly with increasing distance from the shore. The ratios of methylphenanthrenes/phenanthrene and methylpyrene/pyrene are sensitive indicators of the origin of PAH pollution in the Gulf which is mostly pyrolitic. The phenanthrene/anthracene ratio was used to determine the approximate location and distance from the source of PAH pollution, while 1-methy 1-7-isopropylphenanthrene (retene) was used as indicator for forest fires. A sediment depth profile indicates a major increase in the PAH concentrations after the First World War.     

Distribution and origins of polycyclic aromatic hydrocarbons (PAHs) in riverine, estuarine, and marine sediments in Thailand

To assess the status of polycyclic aromatic hydrocarbon (PAH) contamination in coastal and riverine environments in Thailand, we collected 42 surface sediment samples from canals, a river, an estuary, and coastal areas in Thailand in 2003 and analyzed them for PAHs with 3-7 benzene rings by gas chromatography-mass spectrometry (GC-MS). The total concentration of PAHs ranged from 6 to 8399 ng/g dry weight. The average total PAH concentrations were 2290+/-2556 ng/g dry weight (n=8) in canals, 263+/-174 (n=11) in the river, 179+/-222 (n=9) in the estuary, and 50+/-56 (n=14) in coastal areas. Comparison of the concentration range with a worldwide survey of sedimentary PAH concentrations ranked PAH contamination in Thai sediments as low to moderate. The ratio of the sum of methylphenanthrenes to phenanthrene (MP/P ratio) allows discrimination of PAH sources between petrogenic (>2) and pyrogenic (<0.5) origins. Sediments from urban canals in Bangkok showed the highest PAH concentrations and petrogenic signatures (MP/P=1.84+/-0.98 [n=6] in canal sediments) with abundant alkylated PAHs, indicating major sources of petrogenic PAHs in the city. To identify the sources of the petrogenic inputs in Thailand, we analyzed triterpanes, biomarkers of petroleum pollution, in the sediment samples and in potential source materials. Hopane profiles were remarkably uniform throughout the nation, suggesting a diffuse single source (e.g. automobiles). Molecular profiles of hopanes and PAHs in sediments from the urban canals were similar to those in street dust, indicating that street dust is one of the major sources of petrogenic PAHs in the urban area. On the other hand, low levels of PAHs (approximately 50 ng/g) with a pyrogenic signature (MP/P ratio approximately 0.5) were widely recorded in remote areas of the coast and the Chao Phraya River. These pyrogenic PAHs may be atmospherically transported throughout the nation. Middle and lower reaches of the Chao Phraya River, the river mouth, and the upper Gulf of Thailand showed intermediate concentrations and profiles of PAHs, indicating mixtures of petrogenic and pyrogenic origins. Perylene was abundant in sediments, representing up to approximately 60% of total identified PAHs. High inputs of soil due to frequent heavy rains could contribute to the high perylene abundance in the sediments. Sedimentary PAH concentrations decreased offshore with a half distance of approximately 10 km in the upper Gulf off the mouth of the Chao Phraya River. This is probably due to active deposition of laterally transported riverborne particles.     

Distribution and sources of polycyclic aromatic hydrocarbons in surface sediments of the Hormuz strait,Persian Gulf

The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) were determined in the sediment from the Hormuz strait, Persian Gulf. The sum of 16 PAHs (ΣPAH) concentrations varied from 72.17 to 277.77 ng g⁻¹ dry weight, with an average value of 131.20 ± 59.29 ng g⁻¹ dry weight. An ecological risk assessment of PAHs, indicated that adverse biological effects caused by acenaphthene and acenaphthylene occasionally may take place in the sediment of Hormuz strait. PAH source identification showed that the PAHs in the sediments come from pyrogenic and mixed origin. Based on classification of pollution levels, sediments from Hormuz strait could be considered as low to moderately polluted with PAHs.     

Enrichment and partitioning of polycyclic aromatic hydrocarbons in the sea surface microlayer and subsurface water along the coast of Xiamen Island,China

Sea microlayer (SML) and subsurface water (SSW) samples were collected around Xiamen Island to study the enrichment and partitioning of polycyclic aromatic hydrocarbons (PAHs). Total PAH concentrations ranged from 93.43 to 411.05 ng L⁻¹ in the SML and 49.29–279.42 ng L⁻¹ in the SSW. Compared with the results of previous studies before pollution control measurements, PAHs levels decreased significantly. The enrichment factors (EFs) of dissolved and particulate PAHs varied from 0.68 to 2.71 and 0.43–3.56. EFs showed the consistent enrichment trends with sites and exhibited different enrichment characteristics between 2 and 3 ring PAHs and 4 ring PAHs. Furthermore, the much higher concentrations of BaP (strong carcinogenicity) were accompanied by higher EFs in the SML samples from the Western Xiamen Harbour, which together indicated the risk of impacts to the fish eggs that usually float on the SML water after exposure to oil spills and combustion, contributed directly by the port and shipping activities.     

Polycyclic aromatic hydrocarbons in coastal sediments of southwest Taiwan: An appraisal of diagnostic ratios in source recognition

Fifty-seven surface sediment samples were collected from the coast of southwest Taiwan and analyzed for polycyclic aromatic hydrocarbons (PAHs). Concentrations of total PAHs (28 PAH compounds) ranged from 15 to 907 ng g⁻¹ dry weight. Diagnostic ratios showed that PAHs in the sediments of the Gaoping estuary were predominantly of petroleum origin, whereas sediments from the Kaohsiung coast contained principally combustion-derived PAHs. Principal component analysis indicated that emissions from automobiles and coal burning were the main sources of combustion-derived PAHs. The relatively high ratios of perylene/penta-aromatic PAH isomers in sediments from the Tainan coast and some off-shore stations on the Kaohsiung coast suggest a significant diagenetic PAH contribution. The study shows that certain diagnostic ratios are useful and sensitive in delineating the distribution of PAHs from specific sources in southwest Taiwan. The phenanthrene/anthracene ratio is a better indicator than the methylphenanthrenes/phenanthrene ratio for tracing petrogenic PAHs, and the benzo(a)anthracene/chrysene and indeno(1,2,3-c,d)pyrene/benzo(g,h,i)perylene ratios are more specific than the benzo(a)pyrene/benzo(e)pyrene and benzo(b)fluoranthcene/benzo(k)fluoranthcene ratios in distinguishing PAHs from various pyrogenic sources.     

Biological risk and pollution history of polycyclic aromatic hydrocarbons (PAHs) in Nansha mangrove,South China

Chinese government has taken various measures to alleviate pollution caused by polycyclic aromatic hydrocarbons (PAHs) in the region of Pearl River Delta since the economic reform in 1978, but the effectiveness of these measures remains largely unknown. This study aimed to elucidate the biological risk and pollution history of PAHs by measuring the concentrations of 28 PAHs in the surface and core sediments, respectively, in Nansha mangrove. Results found that the biological risk of PAHs was low without obvious spatial variation. The PAH concentration along the depth gradient indicated that PAH pollution was stabilized since the early 1990s while the source of PAHs has gradually changed from combustion of coal to petroleum products. This implied that the mitigation measures taken by the Chinese government were effective. Compared to marine bottom sediment, we propose that using mangrove sediment can provide a more accurate and precise estimate of pollution history of PAHs.     

河北王快水库沉积物多环芳烃的分布、来源及生态风险评价

对王快水库沉积物中16种多环芳烃含量进行了检测,结果表明,王快水库沉积物多环芳烃含量处于中等污染水平.多环芳烃总含量由库区上游到坝前逐渐升高,多环芳烃总含量在沉积物纵向上的总体分布趋势是随着剖面深度的增加而降低,低环的萘和菲,高环的荧蒽、苯并[b]荧蒽、屈和芘是沉积物中主要的优势化合物,表层和剖面沉积物中多环芳烃的含量与有机碳含量呈正相关关系,相关系数分别为0.8154和0.9534.王快水库沉积物中多环芳烃主要来源化石燃料及生物质的燃烧,风险评价结果表明,严重的多环芳烃生态风险在王快水库沉积物中不存在,但是芴化合物含量超过了风险评价低值,可能存在着对生物的潜在危害.     

Distribution and source recognition of polycyclic aromatic hydrocarbons in the sediments of Hsin-ta Harbour and adjacent coastal areas,Taiwan

Thirty-three sediment samples from Hsin-ta Harbour and neighboring coastal areas were analyzed by GC-MS for polycyclic aromatic hydrocarbons (PAHs). Total concentrations of 30 analyzed parental and alkylated PAHs ( summation operator PAH) varied from 98.1 to 3382 ng/g dry weight. MP/P (methylphenanthrenes/phenanthrene) values larger than 2 coincided with very low P/A (phenanthrene/anthracene) values at inner harbour stations, revealing that a significant portion of low molecular weight PAHs are probably from petrogenic pollution sources, specifically, illegal disposal of used motor oil. The 4,6-dimethyldibenzothiophene/3,6-dimethylphenanthrene (4,6-C(2)D/3,6-C(2)P) ratio is found to be more useful than the MP/P ratio in tracing petrogenic PAHs from the inner harbour area to the adjacent coastal environment. In addition, according to hierarchical cluster analysis, collected sediments cluster in three major groups, Off-shore Group, Near-shore Group and Inner Harbour Group. Three diagnostic ratios, 4,6-C(2)D/3,6-C(2)P, PER/ summation operator PAH (perylene to summation operator PAH) and BaA/CHR (benzo(a)anthracene/chrysene), representing petrogenic, biogenic and pyrogenic origins, are found to be effective in differentiating and characterizing sediments among the groups in this study. Enrichment of pyrogenic and petrogenic PAHs in sediments collected exhibits mixing or dilution, spatially, by biogenic (or natural) PAHs.     

The Consequences of the Oder Flood in 1997 on the Distribution of Polycyclic Aromatic Hydrocarbons in the Oder River

Changes in the levels and spatial distribution of PAHs as a consequence of the Oder flood in the summer of 1997 were investigated in post‐flood sediments from the Oder River and the Oder Lagoon. The aim of this study was to identify sources of the PAH pollution and in particular investigate polluted sites (“hot spots”) in the most highly suspected locations of the drainage area. Molecular indices based on isomeric PAH ratios and the ratio of the parent PAHs to methylated PAHs were used to distinguish between the pollution sources. Elevated levels of PAHs were discovered in the post‐flood sediments of the Oder River in comparison to the average regional values. Elevated concentrations of PAHs were also found in fluffy layer samples taken from the Oder Lagoon and the Pomeranian Bight in late August. The highest concentrations of PAHs were observed near power plants or roads with heavy traffic. Most of the contamination originates from high temperature pyrogenic sources with some slight overlays of petrogenic sources. These increased concentrations of pyrogenic origin may be attributable to flooding of municipal and industrial waste disposal areas in the Oder River drainage.     

Distribution,sources, and ecological risk assessment of polycyclic aromatic hydrocarbons in surface sediments from the Nantong Coast,China

The distribution, sources, and ecological risk assessment of 16 polycyclic aromatic hydrocarbons (PAHs) in surface sediments from the Nantong coast in China were investigated. The results indicated that the total concentrations of the 16 PAHs in the surface sediments from the study area ranged from 1.4 to 87.1 ng g^? 1 dw (mean value 19.9 ng g^? 1 dw), which were generally low compared to the adjacent offshore area and other coastal zones around the world. The selected PAH ratios and the principal components analysis for each site showed that petroleum combustion and petrogenic pollution (mainly caused by petroleum spills) were the dominant PAHs sources in the surface sediments of the coast. The ecological risk assessment indicated that most of the individual PAHs had few negative effects in this area.     

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).     

Distribution and partitioning of polycyclic aromatic hydrocarbons (PAHs) in different size fractions in sediments from Boston Harbor, United States.

The concentrations of 16 US EPA priority pollutant polycyclic aromatic hydrocarbons (PAHs) were analyzed in four size fractions (< 62, 62-125, 125-250, and > 250 microm) in three contaminated Boston Harbor sediments. Total PAH concentrations ranged from 7.3 to 358 microg/g dry wt. and varied largely among the different size fractions in these sediments. For all three sites, the highest PAH concentrations were associated with the large size (> 250 microm) fractions while the fine silt and clay fractions (< 62 microm) contained relatively low PAHs. Despite the great concentration differences, the composition of PAHs in the four size fractions of these sediments showed similar patterns dominated by PAHs with three or more rings. By examining the distribution patterns of selected alkyl homologs to parent compounds, the results indicate that the major PAHs contributing to the high contamination in the inner harbor sediments were from pyrogenic sources. A positive correlation between PAHs and sedimentary organic carbon exists for all size fractions in the sediments. Calculated organic carbon normalized partition coefficients (log K(oc)) for selected major PAHs indicate near-equilibrium partitioning of PAHs among the different size fractions despite their large concentration variations. Sedimentary organic matter associated with different size fractions was the controlling factor for the observed distribution differences of PAHs among the size fractions. Our results also suggest that sedimentary organic matter with different origins and maturities may have somewhat different PAH sorption characteristics. Particulate organic matter of charcoal, plant detritus and Capitella fecal pellets in the sediments appear to sorb PAHs more strongly than organic matter associated with clay minerals. The strong association of PAHs with these organic particles in sediments will have a great influence not only on their distribution but also on long-term environmental impact.     

Sediment PAH: Contrasting levels in the Caspian Sea and Anzali Wetland

A comparative study of 23 PAH congeners in sediment of the Caspian Sea coast and Anzali Wetland was conducted in 2010. Surface sediment was analyzed using chromatography and mass spectrometry. Total PAH concentrations ranged between 212 and 9009 ng g⁻¹ dw. Spatial distribution maps revealed that PAH levels were higher in the coastal areas of the Caspian Sea where oil related activities have been common since 1800’s. Diagnostic ratios analysis indicated that PAHs largely originated from petrogenic processes. PAH toxicity level was assessed using sediment quality guidelines and toxic equivalent concentrations to determine toxic effects on marine organism. Based on these investigations, in our study areas, the probability of toxicity for benthic organisms is “low to medium”. The toxic equivalent concentrations of carcinogenic PAHs varied between 11 and 231 ng TEQ/g; higher total toxic equivalent concentrations values were found in the coastal areas of the Caspian Sea.     

Legal protection is not enough: Posidoniaoceanica meadows in marine protected areas are not healthier than those in unprotected areas of the northwest Mediterranean Sea

Using the Conservation Index, which measures the proportional amount of dead matte relative to live Posidonia oceanica, we assessed the health of 15 P. oceanica meadows at a regional scale along the coast of Liguria (NW Mediterranean). These areas were characterized by different degrees of anthropization, from highly urbanized sites to marine protected areas. Two different scenarios were identified according to depth: in shallow zones, the health of P. oceanica meadows was related to the degree of anthropization along the coastline. In contrast, in deep zones, most meadows exhibited poor health, independent of both the degree of disturbance and the legal measures protecting the area. Working synergistically with the regional impact of increased water turbidity, local impacts from the coast were recognized as the main causes of the severe regression of most Ligurian P. oceanica meadows. We conclude that marine protected areas alone are not sufficient to guarantee the protection of P. oceanica meadows. We emphasize the need for a management network involving the Sites of Community Interest (SCIs) containing P. oceanica meadows.     

Fate of polycyclic aromatic hydrocarbon (PAH) contamination in a mangrove swamp in Hong Kong following an oil spill

The fate of polycyclic aromatic hydrocarbon (PAH) contamination in a mangrove swamp (Yi O) in Hong Kong after an oil spill accident was investigated. The concentrations and profiles of PAHs in surface sediments collected from five quadrats (each of 10 m×10 m) covering different degrees of oil contamination and the most contaminated mangrove leaves were examined in December 2000 (30 days after the accident) and March 2001 (126 days later). The concentrations of total PAHs in surface sediments ranged from 138 to 2135 ng g⁻¹, and PAHs concentrations decreased with time. In the most contaminated sediments, total PAHs dropped from 2135 (30 days) to 1196 ng g⁻¹ (120 days), and the decrease was smaller in less contaminated sediments. The percentage reduction in sediment PAHs over three months (44%) was less significant than that in contaminated leaves (85%), indicating PAH in or on leaves disappeared more rapidly. The PAH profiles were very similar in sediments collected from quadrats Q1 and Q2 with benzo[a]anthracene and pyrene being the most abundant PAH compounds, but were different in the other three quadrats. The proportion of the light molecular weight PAHs to total PAHs increased after three months, especially phenanthrene. Results suggest that physical and photo-chemical weathering (tidal washing and photo-oxidation) of crude oil in surface sediments and on plant leaves were important processes in the first few months after the oil spill. The PAH contamination in Yi O swamp came from both petrogenic and pyrolytic sources. The petrogenic characteristic in the most contaminated sediment was confirmed with high values of phenanthrene to anthracene ratio (>10) and low values of fluoranthene to pyrene ratio (0.3–0.4).     

Bayesian spatial modeling of Lavaca Bay pollutants

Locational risk of increased mercury and PAH concentrations in Lavaca Bay, Texas sediments and eastern oysters (Crassostrea virginica) harvested from Lavaca Bay, Texas were analysed. Chemical analysis results were evaluated utilizing Bayesian geo-statistical methods for comparison of the model fit of a random effects model versus a convoluted model which included both random and spatial effects. For those results fit best with the convoluted model, continuous surface maps of predicted parameter values were created. Sediment and oyster concentrations of mercury and the majority of measured PAHs were fit best with the convoluted model. The locational risks of encountering elevated concentrations of these pollutants in Lavaca Bay sediments and oysters were highest in close proximity to industrial facilities.     

Preliminary study on biodegradation of phenanthrene by bacteria isolated from mangrove sediments in Hong Kong

Elevated concentrations of polycyclic aromatic hydrocarbons (PAHs) have been found in mangrove sediments due to anthropogenic pollution, and microbial degradation has been suggested as the best way to remove PAHs from contaminated sediments. The degradation of phenanthrene, a model PAH compound by bacteria, either the enriched mixed culture or individual isolate isolated from surface mangrove sediments was examined. The effects of salinity, initial phenanthrene concentrations and the addition of glucose on biodegradation potential were also investigated. Results show that surface sediments collected from four mangrove swamps in Hong Kong had different degree of PAH contamination and had different indigenous phenanthrene-degrading bacterial consortia. The enriched bacteria could use phenanthrene as the sole carbon source for growth and degrade this PAH compound accordingly. A significant positive relationship was found between bacterial growth and percentages of phenanthrene degradation. The phenanthrene biodegradation ability of the enriched mixed bacterial culture was not related to the degree of PAH contamination in surface sediments. The growth and biodegradation percentages of the enriched mixed culture were not higher than that of the individual isolate especially at low salinity (0 and 10 ppt). High salinity (35 ppt) inhibited growth and biodegradation of phenanthrene of a bacterial isolate but less inhibitory effect was found on the mixed culture. The inhibitory effects of salinity could be reduced with the addition of glucose.