Seasonal Variation Of Polycyclic Aromatic Hydrocarbons Research Articles

Multimedia distribution, dynamics, and seasonal variation of PAHs in Songhua wetland: Implications for ice-influenced conditions

The knowledge of polycyclic aromatic hydrocarbons (PAHs) in wetlands remains limited. There is a research need for the dynamics between interfaces of multimedia when ice is present in this fragile ecosystem. In this study, sediment, open-water, sub-ice water, and ice samples were collected from the Songhua wetland to study the behaviors of PAHs with and without influences from ice. The concentration of all individual PAHs in sub-ice water (370–1100 ng/L) were higher than the open-water collected from non-ice-covered seasons (50–250 ng/L). Enrichment of PAHs in the ice of wetland was found, particularly for high-molecular-weight PAHs (HMW). This could be attributed to the relatively lower polarity of hydrocarbons compounds, making them more likely to remain in the ice layer during freezing. Source assessments reveal common sources for sub-ice water and ice, which differ from those in the open water in non-ice-covered seasons. This difference is primarily attributed to heating activities in the Harbin during winter. The average percentage contributions were 79% for sub-ice water and 36% for ice related to vehicle exhausts and coal combustion. Additionally, wood burning contributed 25% to sub-ice water and 62% to ice. Sediment in the wetland was found to serve as a final deposit particularly for heavier PAHs, especially those with 6 rings. Sediment also has the potential to act as a source for the secondary emission of low-molecular-weight PAHs (LMW) congeners into the water. PAHs in wetland displayed low ecological risk, while HMW PAHs with relative higher ecological risk is recommended to be further monitored.

Modeling the nocturnal/diurnal and seasonal real world absorption spectra of polycyclic aromatic hydrocarbons and their derivatives in two Chinese polluted cities

Brown carbon (BrC), an organic aerosol, plays an important role in radiative forcing. Polycyclic aromatic hydrocarbons (PAHs) and their derivatives such as oxygenated and nitrated polycyclic aromatic hydrocarbons (OPAHs & NPAHs) are the major constituents of BrC and are persistent environmental pollutants. Our strategy here is to utilize time dependent-density functional theory (TD-DFT) to model the absorption spectra of PAHs and their derivatives in two Chinese industrial sites: Qingcheng district (site A) and Longtang town of Qingyuan (site B). These data are corrected for “Real-world” experimental concentrations of PAHs over these cities. For the first time, nocturnal/diurnal and seasonal variations of PAHs are being simultaneously studied under a theoretical framework. These findings show that the absorptions at site A and B take place mainly due to PAHs while OPAHs and NPAHs have negligible contribution. The site A is highly affected by climate forcing caused by these PAHs. The absorption in winter is higher as compared to that of in summer. Our theoretical modeling approach remarkably identifies the most relevant PAHs for climate forcing in both Chinese regions.

Seasonal Variability and Risk Assessment of Atmospheric Polycyclic Aromatic Hydrocarbons and Hydroxylated Polycyclic Aromatic Hydrocarbons in Kanazawa, Japan

Polycyclic aromatic hydrocarbons (PAHs) and hydroxylated PAHs (OH-PAHs) are ubiquitous atmospheric pollutants that are a concern because of their endocrine disrupting activities. In this study, seasonal air sampling was conducted in 2017 and 2018 in Kanazawa, Ishikawa Prefecture, Japan. The concentrations and seasonal variations of PAHs and OH-PAHs were analyzed, and health risks of individual congeners were evaluated based on their relative endocrine activity. The atmospheric concentrations of PAHs and OH-PAHs showed seasonal trends with higher concentrations in the winter (daily average ± standard deviation: 1.00 ± 0.26 ng/m3 for PAHs and 75.06 ± 23.38 pg/m3 for OH-PAHs) and lower concentrations in the summer (0.30 ± 0.09 ng/m3 for PAHs and 17.08 ± 4.83 pg/m3 for OH-PAHs). There were significant positive correlations between the concentrations of atmospheric PAHs and OH-PAHs. Additionally, the health risk from the endocrine disrupting potential of each OH-PAH was evaluated using relative estrogenic and antiestrogenic activities. OH-PAHs with four rings, such as OH-chrysenes and OH-benz[a]anthracene, had particularly high health risks. These results suggest that atmospheric OH-PAHs are a potential health risk for organisms and thus warrant further research.

Seasonal variation and sources of atmospheric polycyclic aromatic hydrocarbons in a background site on the Tibetan Plateau

The study of atmospheric polycyclic aromatic hydrocarbons (PAHs) in northeastern Tibetan Plateau with fragile ecological environment and complex atmospheric circulation system is blank. To understand the characteristics and sources of persistent organic pollutants in the atmosphere of the northeastern Tibetan Plateau, we monitored levels in the central Qilian Mountain. From 2016 to 2017, we collected 45-pair (particle + gas) samples using active air samplers to investigate the sources, transport paths, and their influencing factors. Sources of PAHs were analysed with a source diagnostic model, and atmospheric transport paths were calculated. The concentration range for ∑15PAHs was 439–4666 pg/m3, and the average was 2015 pg/m3. The PAHs in central Qilian Mountain are mainly low molecular weight (LMW) PAHs. Winter concentrations of PAHs were higher than those in summer. The transport of PAHs is mainly affected by westerlies, and there are seasonal differences. Source analysis showed that PAHs mainly came from coal and biomass combustion and vehicle emissions, with seasonal differences. This study clarifies the concentration and seasonal variation of PAHs in the northern Tibetan Plateau, which is conducive to understanding the atmospheric transport process and fate of pollutants. The background site of Qilian Mountains located in the Silk Road economic belt has the value and significance of long-term observation of pollutants.

Spatial and seasonal variations of PAHs in soil, air, and atmospheric bulk deposition along the plain to mountain transect in Hubei province, central China: Air-soil exchange and long-range atmospheric transport

Polycyclic aromatic hydrocarbons (PAHs) are a long-term environmental problem faced by human society. The sources of involuntary PAHs are complex, moreover, secondary emissions of fixed PAHs in the environment occur due to global change and disturbance of human activities. Samples of three environmental media including soil, air, and atmospheric bulk deposition were collected to observe the spatial distribution and seasonal variation, to discuss the source or sink of PAHs and their association with the air mass transport along the plain (Jianghan Plain, JHP) to mountain transect, and explore the geographic scope of the atmospheric transport influence. The results obtained showed that 16 individual PAHs generally existed in all environmental multimedia being studied, and the PAHs concentration in air, soil and deposition flux of atmospheric bulk was higher in JPH than in “Western Hubei Mountains” (WHMs). Considerably high PAHs concentrations were obtained from the soil, air and atmospheric bulk deposition in winter, summer, and both summer and winter, respectively. The air-soil fugacity fraction of PAHs indicated that the soil of Dajiuhu (DJH) is likely to be a sink. Backward air trajectory simulation confirmed that most of the air mass passes over the JHP before reaching DJH, combined with the (transport and persistence level III) TaPL3 model results JHP are acting as sources. However, seasonal changes lead to a shift in the roles of soil sources and sinks. The TaPL3 model calculated that PAHs are transported through water for a wider range of effects and a longer persistence, even up to 10 years.

Seasonal variation of PAHs in marshy sediments from Warri City, Nigeria

Seasonal variation was used to analyse the levels of Polycyclic Aromatic Hydrocarbons (PAHs) in marshy sediments in Warri city, Niger Delta region in Southern Nigeria. Sediment samples were collected from four locations in the city and labelled ST 1, ST 2, ST 3 and ST 4. Control samples were also collected 20 km away from the city and labelled ST 5. The objective of this study is to compare the level of PAHs in dry and rainy season and examine their variation base on the type of PAHs detected in relation to the characteristics of the different locations. The samples were collected from January to March for dry season and June to August for rainy/wet season. Levels of 16 USEPA priority PAHs were determined using GC-FID. Five-ringed benzo(a) pyrene had highest total concentration of 1.342 mg/kg for individual PAHs and it was detected at ST 2 in the dry season. PAHs concentration was higher in dry season than rainy season at all the study sampling stations and the control. ST 4 of the study location had total PAH value of 4.540 mg/kg in dry season. And the control station, ST 5 had total PAH value of 4.18 mg/kg in the same period. In the rainy season, ST 4 had highest total PAH value of 3.029 mg/kg. At ST 5, the highest total value for PAH in rainy season was 1.056 mg/kg. Total PAHs concentration within Warri city was higher than at the control.Keywords: Benzo(a) pyrene; concentration; dry season; Niger Delta; rainy season.

Watershed-scale modeling on the fate and transport of polycyclic aromatic hydrocarbons (PAHs)

PAHs are potentially carcinogenic substances that are persistent in the environment. Increasing concentrations of PAHs were observed due to rapid urbanization, thus; monitoring PAHs concentrations is necessary. However, it is expensive to conduct intensive monitoring activities of a large number of PAHs. This study addressed this issue by developing a multimedia model coupled with a hydrological model (i.e., Soil and Water Assessment Tool (SWAT)) for Taehwa River (TR) watershed in Ulsan, the industrial capital of South Korea. The hydrologic module of the SWAT was calibrated, and further used to simulate the fate and transport of PAHs in soil and waterbody. The model demonstrated that the temporal or seasonal variation of PAHs in soil and waterbody can be well reproduced. Meanwhile, the spatial distribution of PAHs showed that urban areas in TR watershed have the highest PAH loadings compared to rural areas. Sensitivity analyses of the PAH soil and PAH water parameters were also able to determine the critical processes in TR watershed: degradation, deposition, volatilization, and wash off mechanism. We hope that this model will be able to aid the stakeholders in: regulating PAH concentrations emitted by various sources; and also apply the model to other Persistent Organic Pollutants (POPs).

Spatial-temporal distributions, sources of polycyclic aromatic hydrocarbons (PAHs) in surface water and suspended particular matter from the upper reach of Huaihe River, China

The spatial and temporal distribution of polycyclic aromatic hydrocarbons (PAHs) in surface water from the upper reach of Huaihe River were investigated. The water and suspended particulate matter (SPM) samples from 16 sites were collected during three sampling cruises. The concentrations of ΣPAHs ranged from 79.94 to 421.07ng/L with the average values of 140.37ng/L in water and from 10.87 to 201.42ng/L with the average values of 61.23ng/L in SPM. In comparison to survey during March 2007, alleviated PAHs pollution was ascribed to the adjustment of energy structure. LMW PAHs (2- and 3-ring) were abundant in water and SPM samples with high detection frequencies. Seasonal variations of PAHs indicated that high concentrations of PAHs were recorded in the dry period (67.47–560.16ng/L) and low levels of PAHs were detected in the flood period (27.87–458.47ng/L) in water, while the high concentration of PAHs in SPM ranged from 4.14 to 342.32ng/L in the dry period and low concentration from 2.42 to 129.23ng/L in the level period. In situ water-SPM phase distribution revealed that PAHs tended to be transported with water phase in the studied area. Ratios of specific PAHs were calculated to evaluate the possible sources of PAHs contamination, which reflected PAHs in water and SPM derived from the mixed of pyrogenic and petroleum origins in different seasons.

Polycyclic aromatic hydrocarbons (PAHs) in surface sediments of Monastir Bay (Tunisia, Central Mediterranean): distribution, origin and seasonal variations

To assess PAH contamination state of Monastir Bay, surface sediments were collected and analysed for 17 selected parent PAHs by GC/MS. Sediments were sampled from five sites in wet and dry seasons. Total PAH concentrations were in the range of 25.6 to 576.8 ng/g d.wt in winter and 44.9–395.8 ng/g d.wt in summer. Comparison of results with Sediment Quality Guidelines suggested no eco-toxicological risk for benthic organisms. The use of molecular indices has shown that PAHs in surface sediments originate mainly from pyrolytic sources. Total PAH concentrations in surface sediments showed no significant correlations with organic matter content and pelite fraction. The analysis of spatial and seasonal variations of PAHs in surface sediments has demonstrated that final distribution of PAHs in surface sediments is mainly governed by hydrological conditions.

Characterization and Health Risk Assessment of PM10-Bound PAHs in Urban Air of Shenyang, China

PM10 samples were collected at five sampling sites in city center of Shenyang from April 2008 to January 2009. The ambient concentrations of 17 selected polycyclic aromatic hydrocarbons (PAHs) in PM10 were quantified. Spatial and seasonal variations of PAHs were characterized. Based on its BaP and BaP equivalent concentration (BaPeq), the health risk of PAHs in Shenyang was assessed.

Urban fractionation of polycyclic aromatic hydrocarbons from Dalian soils

This report evidences the fractionation of polycyclic aromatic hydrocarbons (PAHs) from urban to rural areas, and a higher contribution of coal and wood combustion in rural areas. PAHs are persistent semi-volatile organic pollutants in the environment. PAHs originate from the incompleted combustion of fossil fuel and biomass. Cities are usually considered as primary sources of PAHs. Due to different types and loads of fuel consumption in various functional areas of a city, the levels and composition profiles of PAHs are expected to be different. We, therefore, studied the mechanisms ruling PAH distributions in soils from a major Chinese city. Seventeen soil samples were collected in urban traffic areas, residential and park areas, suburban areas and rural areas of Dalian, northeastern China. PAHs were analyzed using a high-performance liquid chromatography. The composition profiles and seasonal variation of PAHs were investigated. Results show that the proportions of low-weight molecular PAHs to total PAHs increased with urban-suburban-rural gradient. This trend is explained by the “urban fractionation” of PAHs. Furthermore, the spring/autumn ratios of PAH concentrations were higher than 1. Specifically, the spring/autumn ratio was 1.79 for two ring PAHs, 1.42 for three ring PAHs, and lower than 1.20 for five and six ring PAHs. The spring/autumn ratios of phenanthrene were higher than 1 and increased with increasing distance from the urban areas. The results imply that the contribution of coal and wood combustion PAHs increases with the urban-suburban-rural gradient.

Ice phase as an important factor on the seasonal variation of polycyclic aromatic hydrocarbons in the Tumen River, Northeastern of China

The climatic characteristic is a major parameter affecting on the distribution variation of organic pollutants such as polycyclic aromatic hydrocarbons (PAHs). The Tumen River is located in Northeastern of China. The winter era lasts for more than 5 months in a year, and the river water was frozen and covered by ice phase. Coal combustion is an essential heating source in the Tumen River Basin. The objective of this research is to study ice phase effect on the seasonal variation of PAHs in the Tumen River environment. Samples were collected from 13 sites along the River in March, July, October, and December of 2008. In addition, the ice sample, under ice water and air particulate were also collected in winter. The samples were analyzed for 16 PAHs (naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, beazo[a]anthene, chrysene, beazo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, indeno(1,2,3-cd)pyrene, dibenz(a,h)anthracene, and benzo(ghi)perylene). The compounds were extracted from the water samples and solid samples using LLE and Soxhlet extraction technique, respectively, and it is determined by gas chromatography-mass spectrometry. Among 16 PAHs, fluorene, phenanthrene, and pyrene were found to be present in high concentrations and at high detection frequencies. The total concentration of PAHs in the water, particulate, sediment and ice phase ranged from 35.1-1.05 x 10(3) ng L(-1), 25.4-817 ng L(-1), 117-562 ng g(-1)and 62.8-136 ng g(-1), respectively. The levels of PAHs were generally higher in spring than other seasons. The ice phase in winter acts like a major reservoir of the pollutants and it is major contributor on the seasonal variation of PAHs in Tumen River. The PAHs found in water, particulate, and sediment in the Tumen River were possibly derived from similar pollution sources a proposition based on the compositions and isomer ratios of PAHs. The distribution of PAHs was showed clear seasonal variation in the Tumen River environment, the ice phase and air pollution look like an important factor affecting on the seasonal variation. The ice phase as an important factor affecting on the seasonal variation of PAHs in Tumen River environment. Further studies regarding the effects of air pollution on the river and the mechanisms of migration and transformation of them in the environment are currently being conducted in our laboratory.

Characterization and Source Identification of PM10-bound Polycyclic Aromatic Hydrocarbons in Urban Air of Tianjin, China

PM10 samples were collected at six sampling sites in city center of Tianjin from April 2008 to January 2009. The concentrations of 17 selected polycyclic aromatic hydrocarbons (PAHs) in PM10 were quantified. Spatial and seasonal variations of PAHs were characterized. The dominant PAHs in PM10 samples were fluoranthene, pyrene, benz[a]anthracene, phenanthrene, chrysene, benzo[b]fluoranthene, anthracene, indeno[1,2,3-cd]pyrene and benzo[a]pyrene, accounting for above 85% of total PAHs. The total PAHs concentrations of the six sampling sites ranged from 23.4 to 513 ng/m3. Spatial variations were predominantly due to the different strengths of source emission. The total PAHs concentrations at Dongli Monitoring Station (DL) site and Beichen Science and Technology Park (BC) site were higher than those at other four sites in heating period, while those at Meijiang community (MJ) site and Beichen Science and Technology Park (BC) site were higher in no-heating period. Higher PAHs concentrations during heating period and lower concentrations during no-heating period were observed at the six sampling sites, which may be caused by the stronger emissions from stationary combustion sources in heating period and the quicker air dispersion, washout effects, photo-degradation and higher percentage in the air in vapor phase in no-heating period. The PAHs concentrations in gaseous phase were predicted with gas/particle partition model, and the BaP and BaP equivalency results indicated that the health risk of gas and particle phase PAHs to human in Tianjin were higher than that in other cities. The contributions from potential sources to PAHs in PM10 were estimated by the diagnostic ratios between PAHs and principal component analysis (PCA). In whole sampling period, coal combustion was found to the predominant contributor of PM10-bound PAHs, followed by vehicles emission and wood combustion.

Sources and seasonal variation of PAHs in the sediments of drinking water reservoirs in Hong Kong and the Dongjiang River (China)

The main objective of this study was to investigate occurrence of polycyclic aromatic hydrocarbons (PAHs) in the sources of the drinking water supply of Hong Kong. The main emphasis was on the Dongjiang River in mainland China which is the major source, supplying 80% of the total consumption in Hong Kong (the remaining 20% is obtained from rain water). Sediments were collected from four sites along the Dongjiang River and four reservoirs in Hong Kong during both the dry and wet weather seasons. The concentrations of total PAHs in the sediments ranged between 36 and 539 microg/kg dry wt. The lower levels were detected at the upstream site on the Dongjiang River and at the reservoirs in Hong Kong (44-85 microg/kg dry wt), while the mid- and downstream sites on the Dongjiang River were more polluted (588-658 microg/kg dry wt). Examination of the PAH profiles revealed that the mid- and downstream sections of the Dongjiang River contained high percentages of 4,5,6-ring PAHs, similar to the amounts of atmospheric particulate matter and road dust collected during the dry weather season from the Pearl River Delta region as reported in the literature. Seasonal changes were revealed in the reservoirs of Hong Kong, with higher PAH levels in the wet weather season than in the dry weather season. For those reservoirs in Hong Kong that store water from the Dongjiang River, a distinct seasonal pattern was also observed, namely, that under dry weather season conditions the PAHs found in the sediments were primarily from petrogenic source, while under wet weather season conditions they were from pyrolytic sources. No such pattern was detected in the reservoirs which stored only rain water.

Polycyclic Aromatic Hydrocarbons (PAHs) in the Aerosol of Higashi Hiroshima, Japan: Pollution Scenario and Source Identification

Polycyclic aromatic hydrocarbons (PAHs) are considered to be atmospheric pollutants and well-known human carcinogens. This study analyzes the pollution scenarios of PAHs in the aerosol of Higashi Hiroshima, Japan. We examined the characteristics, the influences of meteorological conditions, the distribution and seasonal variation of PAHs in aerosol samples collected from June 2000 to May 2001. The concentration of PAHs in the aerosol of Higashi Hiroshima was ranging from 11.8 to 157.5 μg/g with a mean concentration of 63.4 μg/g. Results showed that there is positive correlation between aerosol PAH concentrations and ambient temperature but a relatively little correlation with solar radiation. Seasonal variation was observed with a higher concentration during winter and lower concentration during summer. Apart from that, principal component analysis and molecular diagnostic ratios were also used to characterize and identify possible PAHs emission sources. Results obtained strongly suggested that vehicular emissions appeared to be the major source of aerosol PAHs in this study although other sources do have some degree of influence.

Seasonal variation of particulate polycyclic aromatic hydrocarbons associated with PM10 in Guangzhou, China

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants in the urban atmosphere. An investigation on seasonal variation of PAHs in the urban atmosphere of Guangzhou, China was conducted in this study. 112 PM10 (particulate matter with aerodynamic diameter < 10 μm) samples were collected at two sites between June 2002 and June 2003. PAHs were analyzed with GC–MS (gas chromatography–mass spectrometry). The result showed that PAHs exhibit distinct seasonal variation. The seasonal concentration for the ∑PAHs ranged from 8.11 to 106.26 ng m − 3 . The average ∑PAHs measured were highest in winter and lowest in summer. The PAHs distribution patterns were similar within each season at two sites. 5–6 ring PAHs were the abundant compounds, which accounted for 65–90% of ∑PAHs and benzo [b + k] fluoranthene dominated in four seasons. The PAHs concentration and distribution pattern fluctuated greatly in winter for the cold air current. Based on the different temperature in winter, the samples were split into two groups. PM10 and the abundance of the PAHs in winter-1 (temperature, 12–22 °C) were much greater than in winter-2 (temperature, 8–12 °C). In winter-1 benzo [b + k] fluoranthene and Indeno [1, 2, 3] pyrene dominated while chrysene and benzo [b + k] fluoranthene dominated in winter-2. Meteorological conditions such as wind speed and temperature had a strong influence on the seasonal variation. Potential sources of PAHs were identified using the molecular diagnostic ratios between PAHs. Results showed fossil fuel combustion may be the major source of PAHs at the two sites.

Particle-associated polycyclic aromatic hydrocarbons in urban air of Hong Kong

Abstract PM2.5 and PM10 samples were collected at two sampling sites in Hong Kong in wintertime from November 2000 to March 2001 and in summertime from June to August 2001. The concentrations of 16 selected polycyclic aromatic hydrocarbons (PAHs) in aerosols were quantified. Spatial and seasonal variations of PAHs were characterized. The dominated PAHs in PM2.5 and PM10 included benzo[b]fluoranthene, pyrene, fluoranthene, indeno[1,2,3-cd]pyrene and chrysene, accounting for 50–82% of total PAHs. The sum of 16 PAHs in PM2.5 at roadside ranged from 3 to 330 ng/m3, and in PM10 between 5 and 297 ng/m3, whereas at a residential/industrial/commercial site, the total PAHs in PM2.5 was from 0.5 to 122 ng/m3, and 2–269 ng/m3 in PM10. Results indicated that most of the PAHs were in the PM2.5 fraction. Spatial variations were predominantly due to the difference of source strength. For both PM2.5 and PM10, the total PAHs at PU site was higher than that at KT site. The average concentrations of individual PAHs in aerosols at PU site were also higher than that at KT site. Higher winter PAHs concentrations and lower summer concentrations were observed at the two sites. Higher winter PAHs concentrations were mainly caused by local emission sources superimposed by highly polluted air masses from Mainland China. The lower summer PAHs concentrations were likely due to easier dispersion of air pollutants, washout effects and to a lesser extent, photo-degradation and higher percentage in the air in vapor phase. Potential sources of PAHs in aerosols were identified using the diagnostic ratios between PAHs and PCA analysis. At PU site, vehicular emissions were the main contributors of particle-associated PAHs, and stationary combustion sources may also contribute to the particulate PAHs. On the contrary, at the KT site, PAHs in aerosols were predominantly from gasoline and diesel engines.

Polycyclic aromatic hydrocarbons (PAHs) and carbonyl compounds in urban atmosphere of Hong Kong

Polycyclic aromatic hydrocarbons (PAHs) and carbonyls compounds are becoming a major component of atmospheric toxic air pollutants (TAPs) in Hong Kong. Many studies in Hong Kong show that traffic emission is one of the most significant contributors in urban area of Hong Kong. A twelve months monitoring program for PAHs and carbonyl compounds started on 10 April 1999 including a two weeks intensive sampling in winter had been performed at a roadside urban station at Hong Kong Polytechnic University in order to determine the monthly and seasonal variations of PAHs and carbonyl concentrations. The objective of this study is to characterize the roadside concentrations of selected TAPs (PAHs and carbonyl compounds) and to compare with the long-term compliance monitoring data acquired by Hong Kong Environmental Protection Department (EPD). Monthly variations, seasonal variations and winter/summer ratios at the monitoring station are discussed.

Polycyclic aromatic hydrocarbons in water and sediment of the Baltic Sea

Between 1992 and 1994, the distribution of 15 polycyclic aromatic hydrocarbons (PAHs) was investigated in seawater and surface sediments of the Baltic Sea. The analysis of PAHs in seawater is very difficult due to the low concentration. High separation capability is required. A method for analysing very low concentrations of PAHs is presented. The method is based on the high-performance liquid chromatography (HPLC) with fluorescence detection. The concentrations of PAHs in seawater are discussed in relation to water depth. A seasonal variation of PAHs in seawater was observed, with lowest concentrations occurring in summer and generally higher concentrations occurring in November. According to the regional distribution, elevated concentrations of PAHs were found in coastal regions of the Baltic Sea. The regional distribution of PAHs in surface sediments of the Belt Sea and the Arkona Basin were also investigated. The relationship between the content of PAHs and the percentage of total organic carbon in sediments is discussed.