Ring PAHs Research Articles

Biodegradation of dispersed Macondo crude oil by indigenous Gulf of Mexico microbial communities

Because of the extreme conditions of the Deepwater Horizon (DWH) release (turbulent flow at 1500m depth and 5°C water temperature) and the sub-surface application of dispersant, small but neutrally buoyant oil droplets <70μm were formed, remained in the water column and were subjected to in-situ biodegradation processes. In order to investigate the biodegradation of Macondo oil components during the release, we designed and performed an experiment to evaluate the interactions of the indigenous microbial communities present in the deep waters of the Gulf of Mexico (GOM) with oil droplets of two representative sizes (10μm and 30μm median volume diameter) created with Macondo source oil in the presence of Corexit 9500 using natural seawater collected at the depth of 1100–1300m in the vicinity of the DWH wellhead. The evolution of the oil was followed in the dark and at 5°C for 64days by collecting sacrificial water samples at fixed intervals and analyzing them for a wide range of chemical and biological parameters including volatile components, saturated and aromatic hydrocarbons, dispersant markers, dissolved oxygen, nutrients, microbial cell counts and microbial population dynamics. A one phase exponential decay from a plateau model was used to calculate degradation rates and lag times for more than 150 individual oil components. Calculations were normalized to a conserved petroleum biomarker (30αβ-hopane). Half-lives ranged from about 3days for easily degradable compounds to about 60days for higher molecular weight aromatics. Rapid degradation was observed for BTEX, 2–3 ring PAHs, and n-alkanes below n-C23. The results in this experimental study showed good agreement with the n-alkane (n-C13 to n-C26) half-lives (0.6–9.5days) previously reported for the Deepwater Horizon plume samples and other laboratory studies with chemically dispersed Macondo oil conducted at low temperatures (<8°C). The responses of the microbial populations also were consistent with what was reported during the actual oil release, e.g. Colwellia, Cycloclasticus and Oceanospirillales (including the specific DWH Oceanospirillales) were present and increased in numbers indicating that they were degrading components of the oil. The consistency of the field and laboratory data indicate that these results could be used, in combination with other field and model data to characterize the dissipation of Macondo oil in the deepwater environment as part of the risk assessment estimations.

Potential threat of heavy metals and PAHs in PM2.5 in different urban functional areas of Beijing

Beijing, as the capital of China, is one of the most populous cities in the world. With the fine particulate matter pollution being increasingly serious, daily exposure to hazardous ingredients caused more and more attention. Current research concerning risk evaluation in Beijing was relative less. In November, 2013, samples were collected in seven different functional areas of Beijing, so as to better understand the risk to human health caused by particle matter pollution in this region. PM2.5 pollution in rural and urban Beijing was relative high under haze–fog days in comparison with non haze–fog value. Zn and Ba showed the highest concentration levels among non-carcinogenic metals. The non-carcinogenic metal concentration at all the sites ranged in the same order: Ce, Pb, Cu, V and Sb. Higher ring PAHs (with four to six rings) were the dominant species and constituted more than 90% of the Σ14PAHs. Pb (4.34×10−4 for men, 3.73×10−4 for women) presented the maximum risk level for non-carcinogenic heavy metals in the whole study area. While, risk levels of Cr at residential areas, schools, Olympic Park and rural countryside exceeded the limit for adults. In haze–fog days, the carcinogenic PAH risk level in each functional area ranged in the order: rural countryside>inner suburban district>Olympic Park>city central>schools>ecological reserve>residential areas. To some extent, benzo(a)pyrene may had a potential risk to adults, and other carcinogenic PAHs were all under average risk acceptance.

Catalytic Oxidation of Pahs in Wastewater / Katalityczne Utlenianie Wwa w Ściekach

The aim of the investigations was to determine the effectiveness of the removal of 4, 5 - ring PAHs from coking wastewater using dihydrogen dioxide in the presence of a cobalt, platinum or titanium catalyst. A dose 7.4 mL of dihydrogen dioxide in the amount of and 14.8 mL/L of the analyzed sample were added to the samples. The samples were shaken and stored under laboratory conditions for 12 hours. The concentration of PAHs before and after the oxidation process were determined. The quantitative and qualitative chromatographic analysis was carried out using a gas chromatograph coupled with a mass spectrometer (GC-MS). The total concentration of 8 PAHs before oxidation reached the value of 9150 ng/L The concentration of 4-ring compounds and 5-ring PAHs were equal to 6390 ng/L and 2760 ng/L, respectively. The highest decrease (93%) the sum of 8 hydrocarbons using a dose of oxidizer 7.4 ml/L and in the presence of titanium catalyst was achieved.

Kinetics of PAH degradation by a new acid-metal-tolerant Trabulsiella isolated from the MGP site soil and identification of its potential to fix nitrogen and solubilize phosphorous

Development of an efficient bioinoculum is considered as an appropriate remedial approach to treat the PAHs-metal mixed contaminated sites. Therefore, we aimed to isolate a degrader able to exert an outstanding PAH catabolic potential with added traits of pH-metal-resistance, N-fix or P-solubilization from a manufactured gas plant site soil. The identified strain (MTS-6) was a first low and high molecular weight (LMW and HMW) PAHs degrading Trabulsiella sp. tolerant to pH 5. MTS-6 completely degraded the model 3 [150mgL−1 phenanthrene (Phe)], 4 [150mgL−1 pyrene (Pyr)] and 5 [50mgL−1 benzo[a]pyrene (BaP)] ring PAHs in 6, 25 and 90 days, respectively. Presence of co-substrate (100mgL−1 Phe) increased the biodegradation rate constant (k) and decreased the half-life time (t1/2) of HMW PAHs (100mgL−1 Pyr or 50mgL−1 BaP). The strain fixed 47μgmL−1N and solubilized 58μgmL−1P during PAH metabolism and exhibited an EC50 value of 3–4mgL−1 for Cu, Cd, Pb and Zn. Over 6mgL−1 metal levels was lethal for the microbe. The identified bacterium (MTS-6) with exceptional multi-functional traits opens the way for its exploitation in the bioremediation of manufactured gas plant sites in a sustainable way by employing bioaugmentation strategy.

Real-World Emission from In-Use Construction Equipment in China

ABSTRACTIn-use emission factors of 11 pieces of construction equipment were collected using a portable emission measurement system. These vehicles include excavators, bulldozers and loaders. Both regulated pollutants and PM carbonaceous compositions were tested. The emission factors of CO, HC, NOx and PM for these vehicles are 13–91 g kg–1, 12–63 g kg–1, 1.4–27 g kg–1, and 2.5–13 g kg–1 respectively. Their fuel consumption rates are also provided. The vehicles in the idling mode are higher in the emission factors of CO and HC than those in the other operating modes. The vehicles certified to different emission standards are significantly different in PM carbonaceous compositions. The analysis by GC-MS shows that the majority of particle-phase PAHs from these vehicles are 2- or 3-ring PAHs, while high-molecular-weight PAHs are seldom detected. There is a great difference in the emission factors of PM and OM between the vehicles at the start-up phase and those in the normal idling mode. Some conclusions and recommendations are made by comparing this study with some others.

Direct Analysis of Low-Volatile Molecular Marker Extract from Airborne Particulate Matter Using Sensitivity Correction Method.

Molecular marker analysis of environmental samples often requires time consuming preseparation steps. Here, analysis of low-volatile nonpolar molecular markers (5-6 ring polycyclic aromatic hydrocarbons or PAHs, hopanoids, and n-alkanes) without the preseparation procedure is presented. Analysis of artificial sample extracts was directly conducted by gas chromatography-mass spectrometry (GC-MS). After every sample injection, a standard mixture was also analyzed to make a correction on the variation of instrumental sensitivity caused by the unfavorable matrix contained in the extract. The method was further validated for the PAHs using the NIST standard reference materials (SRMs) and then applied to airborne particulate matter samples. Tests with the SRMs showed that overall our methodology was validated with the uncertainty of ~30%. The measurement results of airborne particulate matter (PM) filter samples showed a strong correlation between the PAHs, implying the contributions from the same emission source. Analysis of size-segregated PM filter samples showed that their size distributions were found to be in the PM smaller than 0.4 μm aerodynamic diameter. The observations were consistent with our expectation of their possible sources. Thus, the method was found to be useful for molecular marker studies.

Coal-related sources of organic contamination in sediments and water from the Bierawka River (Poland)

River sediments mixed with coaly material occur all along the length of the Bierawka River (Poland). To identify the origin of the coal in the sediment, the coaly material was investigated by reflected light microscopy and Rock Eval Pyrolysis, and solvent extracts by gas chromatography–mass spectrometry (GC–MS). Organic compounds dissolved in water were separated by solid phase extraction (SPE) and analyzed by GC–MS. The results point to a kerogen III source. Petrographic analyses confirm abundant coal-, charred- and coked particles in the sediments. Vitrinite reflectance varied between 0.66–0.80 Rr% without any large spatial variation. The coaly particles have different sources. Generally, the primary origin of coal particles is from coal processing and the dumping the ash with unburned coal particles from a glass factory near the river source. Later, this material was redeposited along the entire river course. In addition, hard coal processing (crushing–washing) features are visible in larger coal pieces. A second source of coaly organic matter is a coal waste dump at Szczygłowice where intensive erosion of steep slopes has delivered copious amounts of organic matter into the river. The mixing of this organic matter with that from the glass factory is clearly identified on a ternary diagram. PAH distributions also show differences between sections. The coal particle input from the waste dump increased the relative content of naphthalene relative content downstream. As in the coal waste, 4–5 ring PAHs predominate in the sediments. The pyrogenic origin of PAHs and aromatic compounds such as methylbiphenyls and dibenzofurane in the sediment is indicated by diagnostic PAH ratios; burned particles were identified petrographically. The river water contains only 2–3 ring PAHs, possibly of industrial origin or leached from coal particles in the river sediments.

Studies on polycyclic aromatic hydrocarbons in surface sediments of Mithi River near Mumbai, India: Assessment of sources, toxicity risk and biological impact

This study investigated the levels, sources and potential risks of 17 polycyclic aromatic hydrocarbons in surface sediment samples collected along the Mithi River of Mumbai. The concentration level of ΣPAHs found in the present study was in the range of 1206–4735ng/gdw. The composition patterns of PAHs by ring size in sediment were surveyed which indicate the dominance of four rings followed by five and three ring PAHs. In the study it was observed that the high molecular weight PAHs (HMW PAHs) made greater contributions of 90.83% as compared to that of low molecular PAHs (LMW PAHs) contributing to 9.17% to the total PAH concentrations. Toxicity and biological risk were assessed using toxic equivalent quantity and sediment quality guideline quotient. It is feared that the pollution level of PAHs in the sediments might increase in coming times resulting in an unconspicuous risks for the environment and humans through food chains.

Status of PAHs in Environmental Compartments of South Africa: A Country Report

This article covers the status of PAH concentrations and composition patterns in surface water, air, sediment, and soil samples from South Africa. Despite South Africa being one of the largest economies in Africa, it is only recently that researchers have reported the presence and possible sources of these compounds in various environmental compartments. This article discusses the potential hotspots and possible sources of these compounds. It also compares the total PAH concentrations and percentage composition patterns of the individual PAHs. So far, total concentrations of five PAHs determined in sediment samples from the Johannesburg area, Gauteng Province, gave the highest concentrations ranging from 1233–136,276 μg kg−1. The total concentration of six PAHs found in runoff water from the Venda region of the Limpopo Province, gave the highest concentration with a range of 28.7–3192.6 μg L−1. The decreasing order of percentage composition of PAHs in water samples tended to follow 3-ring > 4-ring > 2-ring PAHs. In soil samples the decreasing order of percentage composition followed 4-ring > 3-ring > 5-ring > 2-ring > 6-ring PAHs. The total freely dissolved PAHs followed solubility of the compounds with 2-ring > 3-ring > 4-ring > 5-ring > 6-ring PAHs. Some of the identified sources of PAHs using molecular ratios include petrogenic emissions such as from petroleum combustion from vehicles and pyrolytic sources such as coal combustion by coal powered power stations, as well as iron and steel production industries. Oil spills were also identified as major PAH contributor in runoff water from the Venda region of the Limpopo Province.

Formation mechanisms of soot from high-molecular-weight polycyclic aromatic hydrocarbons

The feedstocks, including benzene, acetylene, and benzene with acetylene or 2–7 ring PAH, were pyrolyzed in an isothermal laminar flow at 1400–1650K. The particle size distributions (PSDs) of soot and nascent soot were analyzed using a scanning mobility particle sizer (SMPS). The morphology of particles with the same mobility particle diameter was examined using a scanning electron microscope (SEM), where the grid was sampled via thermophoretic sampling assisted by a differential mobility analyzer (DMA). The soot produced by the pyrolysis of acetylene at 1400K exhibited the highest number concentration and a log-normal distribution compared with those of the soot produced by the pyrolysis of benzene and the PAH additives. At 1500K, the pyrolysis of PAHs with three or more rings with zigzag sites significantly increased the number concentration, although the added carbon concentration was smaller than that of acetylene. The addition of dibenzo[a,e]pyrene, which possesses three armchair sites, inhibited soot formation, suggesting that the bay site is easily formed and that the formation of anisotropic PAHs inhibits dimerization. The morphology of the soot formed by the addition of dibenzo[a,e]pyrene exhibited a primary particle diameter of 10nm and similar primary particles, whereas the morphology of the soot formed by the addition of PAHs with zigzag sites clearly indicated a structure with a primary particle diameter of 20–40nm. These observations indicate that the incipient soot is formed by the formation of dimers or small clusters of large PAHs via the mechanisms of aromatic molecule addition to aromatic radicals referred to as the PAH–addition cyclization (PAH–AC) mechanism at high temperatures, whereas moderate-sized PAHs developed via the hydrogen-abstraction–carbon-addition (HACA) mechanism form clusters and incipient soot at relatively low temperatures.

Isolation and Characterization of Three and Four Ring Pahs Degrading Bacteria from Contaminated Sites, Ankleshwar, Gujarat, India

Polycyclic aromatic hydrocarbon (PAH)-degrading bacteria were isolated from prolong contaminated Amalakhadi sediment and crude oil polluted soil Telva, near Ankleshwar Gujarat India. Organisms were treated with two-model PAHs compound Anthracene (ANT), and Pyrene (PYR) as the sole source of carbon and energy. Identification of the isolates was carried out based on their morphological and partial 16S rRNA gene sequences, which revealed that the isolates belong to two main bacterial groups: gram-negative pseudomonas indoxyladons and gram-positive, spore-forming group, Bacillus benzoevorans. GC-MS based degradation study demonstrated that P. indoxyladons efficiently degrade 98% of ANT and PYR by 93.2 % when treated with 250 mg L-1. However, B. benzoevorans could tolerate to 200 mg L-1of PYR. Thus, the findings of the study provide novel bacterial sp. having different capacity to degrade model PAHs compounds and further could be utilized for the standardization of bioremediation protocols for ex situ and in situ studies in aquatic as well as terrestrial ecosystem.DOI: http://dx.doi.org/10.3126/ije.v4i1.12184International Journal of Environment Volume-4, Issue-1, Dec-Feb 2014/15, Page: 130-140

Source apportionment of gaseous and particulate PAHs from traffic emission using tunnel measurements in Shanghai, China

Understanding sources and contributions of gaseous and particulate PAHs from traffic-related pollution can provide valuable information for alleviating air contamination from traffic in urban areas. On-road sampling campaigns were comprehensively conducted during 2011–2012 in an urban tunnel of Shanghai, China. 2–3 rings PAHs were abundant in the tunnel's gas and particle phases. Diagnostic ratios of PAHs were statistically described; several were significantly different between the gas and particle phases. Principal component analysis (PCA), positive matrix factorization (PMF), bivariate correlation analysis and multiple linear regression analysis (MLRA) were applied to apportion sources of gaseous and particulate PAHs in the tunnel. Main sources of the gaseous PAHs included evaporative emission of fuel, high-temperature and low-temperature combustion of fuel, accounting for 50–51%, 30–36% and 13–20%, respectively. Unburned fuel particles (56.4–78.3%), high-temperature combustion of fuel (9.5–26.1%) and gas-to-particle condensation (12.2–17.5%) were major contributors to the particulate PAHs. The result reflected, to a large extent, PAH emissions from the urban traffic of Shanghai. Improving fuel efficiency of local vehicles will greatly reduce contribution of traffic emission to atmospheric PAHs in urban areas. Source apportionment of PM10 mass was also performed based on the organic component data. The results showed that high-temperature combustion of fuel and gas-to-particle condensation contributed to 15–18% and 7–8% of PM10 mass, respectively, but 55–57% of the particle mass was left unexplained. Although the results from the PCA and PMF models were comparable, the PMF method is recommended for source apportionment of PAHs in real traffic conditions. In addition, the combination of multivariate statistical method and bivariate correlation analysis is a useful tool to comprehensively assess sources of PAHs.

Concentrations and Profiles of Polycyclic Aromatic Hydrocarbons in Some Commercial Brands of Tea-, Coffee-, and Cocoa-Based Food Drinks in Nigeria

Concentrations and profiles of polycyclic aromatic hydrocarbons were determined in some popular commercial brands of tea-, coffee-, and cocoa-based food drinks in Nigeria by gas chromatograph-flame ionization after hexane/dichloromethane extraction and clean up. The concentrations of the ∑16 Polycyclic aromatic hydrocarbons in these products ranged from 5.2–913.1, 38.7–593.1, and 38.0–1406.4 μg kg−1 for tea-, coffee-, and cocoa-based food drinks, respectively. The polycyclic aromatic hydrocarbon profiles indicate the dominance of three and four rings PAHs in these food items. The concentrations of the European Food Safety Authority (EFSA) eight carcinogenic polycyclic aromatic hydrocarbons ranged from nd–218.9, nd–102.9, and nd–1248.5 μg kg−1 for tea-, coffee-, and cocoa-based food drinks, respectively.

The Coagulant Type Influence on Removal Efficiency of 5- and 6-Ring Pahs During Water Coagulation Process

The article presents results on investigation of the removal efficiency of selected 5- and 6-ring polycyclic aromatic hydrocarbons (benzo[a]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[j]fluoranthene, benzo[g,h,i]perylene, indeno[1,2,3-cd]pyrene, dibenzo[a,h]anthracene) from water during coagulation and sedimentation process. Two pre-hydrolyzed aluminum coagulants: PAX XL 19H and FLOKOR 105V were chosen for research. Process was carried out at optimum process parameters: rapid-mixing - 3 min at the rotational speed of 200 rpm, slow mixing - 10 min at 30 rpm, sedimentation - 60 min. The removal effectiveness was dependant on coagulant type and its composition. Better results in the removal of 5-and 6-ring PAHs were obtained after application of FLOKOR 105V (lower aluminum content) than after using PAX XL 19H.

Combination of Unmix and PMF receptor model to apportion the potential sources and contributions of PAHs in wetland soils from Jiaozhou Bay, China

16 PAHs in Jiaozhou Bay wetland soils were analyzed by GC/MS. The potential sources and contributions were apportioned by Unmix and PMF models. The total concentrations of PAHs ranged from 176.1 to 563.3ng/g with a mean of 345.3ng/g. 2- and 3- rings PAHs were the dominant species accounting for 34.7–87.3% of the total PAHs. The similarities and differences of sources and contributions estimated by Unmix and PMF models were discussed. Three common sources (petrogenic source, coking oven and coal combustion) identified by two models, contributed 43.2%, 39.2% and 12.6% by Unmix and 33.5%, 29.1% and 16.0% by PMF to the total PAHs, respectively. In addition, diesel emission source (5.0%) by Unmix and a mixed source of diesel emission and natural gas burning (21.4%) by PMF were also extracted. It is essential to apply multiple source apportionment techniques to estimate potential source and contributions in further study.

Occurrence, sources, and potential toxicity of polycyclic aromatic hydrocarbons in surface soils from the Yellow River Delta Natural Reserve, China.

A total of 46 surface soil samples collected from the experimental area, buffer area, and core area of the Yellow River Delta Natural Reserve (YRDNR), China, and an adjacent area outside the reserve were analyzed for 23 PAHs including highly carcinogenic dibenzopyrene isomers. The total concentrations ranged from 87.2 to 319 ng/g for ∑23PAHs and 79.2 to 311 ng/g for ∑16PAHs with average concentrations of 133 and 119 ng/g, respectively. Pearson correlation analysis implied that the total polycyclic aromatic compound (PAH) concentrations had a significant positive correlation with the total organic carbon content on the condition that four sites with abnormal values were removed. Low molecular-weight 2- to 3-ring PAHs predominated in the present study. Source diagnostics based on PAHs isomer ratios, principal component analysis, and multiple linear regression suggested that petroleum contributed most to the PAH contamination in the YRDNR, whereas a potential toxicity assessment using BaPeq indicated that the four dibenzopyrenes were the major carcinogenic PAH contributors in the area under investigation, although their concentrations only represented a small proportion of the total PAH concentrations.

Degradation of polycyclic aromatic hydrocarbons in soil by a tolerant strain of Trichoderma asperellum.

Trichoderma asperellum H15, a previously isolated strain characterized by its high tolerance to low (LMW) and high molecular weight (HMW) PAHs, was tested for its ability to degrade 3-5 ring PAHs (phenanthrene, pyrene, and benzo[a]pyrene) in soil microcosms along with a biostimulation treatment with sugarcane bagasse. T. asperellum H15 rapidly adapted to PAH-contaminated soils, producing more CO2 than uncontaminated microcosms and achieving up to 78 % of phenanthrene degradation in soils contaminated with 1,000 mg Kg(-1) after 14 days. In soils contaminated with 1,000 mg Kg(-1) of a three-PAH mixture, strain H15 was shown to degrade 74 % phenanthrene, 63 % pyrene, and 81 % of benzo[a]pyrene. Fungal catechol 1,2 dioxygenase, laccase, and peroxidase enzyme activities were found to be involved in the degradation of PAHs by T. asperellum. The results demonstrated the potential of T. asperellum H15 to be used in a bioremediation process. This is the first report describing the involvement of T. asperellum in LMW and HMW-PAH degradation in soils. These findings, along with the ability to remove large amounts of PAHs in soil found in the present work provide enough evidence to consider T. asperellum as a promising and efficient PAH-degrading microorganism.

Surfactant-Enhanced Washing of Aged PAH Contaminated Soils: Comparison between Nonionic Surfactant and Anionic Surfactant

Nonionic surfactants Triton X-100 (TX100), Triton X-305 and anionic surfactant SDS were used to desorb PAHs from contaminated soil. The surfactant loss due to sorption/ precipitation and PAH removal efficiency by each surfactant were evaluated. Due to sorption/precipitation, the apparent critical micelle concentration (CMCsoil) values for the 3 surfactants are 1.3-3.8 times their corresponding CMC values in aqueous solutions. The maximal surfactant loss follows the order of SDS&gt;&gt;TX100&gt;TX305. The anionic surfactant SDS is quite different from nonionic surfactants TX100 and TX305 in PAH removal. SDS can effectively remove 3-ring PAHs at very low concentration, but is not so efficient for 5 or 6-ring PAHs. While for nonionic surfactants TX100 and TX305, the removal efficiencies of PAHs increased with increasing surfactant concentration. Nonionic surfactants at low concentration cannot facilitate PAH desorption, but enhance the retardation of PAHs in soil. While anionic surfactant SDS enhanced PAH desorption at all the concentrations.

POLYCYCLIC AROMATIC HYDROCARBONS (PAHs) IN COASTAL SEDIMENTS IN THE NORTH OF VIET NAM

Sediment samples were collected at 6 monitoring stations in the coastal area of North Viet Nam from Tra Co to Cua Lo station and were analysed to determinate PAHs contents. The analysic results shown that the content of total 8 PAHs were ranged from 69.56 to 183.88µg/kg dry weight. The content of total 8 PAHs was highest in Cua Lo station in the south, is lowest in Tra Co station in the north. Content of PAHs in dry season were higher than rainy season from 1.1 - 1.9 times. The content of PAHs were under the limitation, but Phenanthrene was exceeded the limitation from 1.02 - 2.66 times at all stations. Three - ring PAHs predominated and, occupied from 40.8 - 90.3 percents of total PAHs. The source of PAHs in coastal sediments in the North of Vietnam was from burning processes.

POLYCYCLIC AROMATIC HYDROCARBONS (PAHs) IN COASTAL SEDIMENTS IN THE NORTH OF VIET NAM

Sediment samples were collected at 6 monitoring stations in the coastal area of North Viet Nam from Tra Co to Cua Lo station and were analysed to determinate PAHs contents. The analysic results shown that the content of total 8 PAHs were ranged from 69.56 to 183.88µg/kg dry weight. The content of total 8 PAHs was highest in Cua Lo station in the south, is lowest in Tra Co station in the north. Content of PAHs in dry season were higher than rainy season from 1.1 - 1.9 times. The content of PAHs were under the limitation, but Phenanthrene was exceeded the limitation from 1.02 - 2.66 times at all stations. Three - ring PAHs predominated and, occupied from 40.8 - 90.3 percents of total PAHs. The source of PAHs in coastal sediments in the North of Vietnam was from burning processes.