Atmospheric sources and soil filtering of PAH content in karst seepage waters

The analysis of PAHs (polycyclic aromatic hydrocarbons) in karst environments has provided an assessment of the vulnerability of karst water and the study of PAH records in stalagmites. The major source of PAHs has generally been considered to be the soil. In this study, we report the quantification of PAHs in the ecosystem compartments of a mountain karst system over a snow-melting period and the spring to summer dry period. PAH profiles in karst seepage waters were consistently similar to those in wet deposits, following the change in PAH profiles between winter and summer periods. However, PAH signatures of atmospheric wet deposits were modulated by a loss of the high molecular weight PAHs, which appear to accumulate in soils. A PAH mass balance was calculated during a summer storm event. This mass balance suggests that dry deposits and canopy throughfall could account for the PAH abundance in karst seepage waters. This study demonstrates the ability of organic hydrophobic compounds to be directly transferred from the atmosphere or canopy into seepage waters, giving new emphasis to the study of PAHs recorded in stalagmites.     

Factors affecting pore water hydrocarbon concentrations in Puget Sound sediments

Polycyclic aromatic hydrocarbon (PAH) and aliphatic hydrocarbon concentrations have been determined for sediments and associated pore waters collected at 2 sites (11 stations) in Puget Sound, Washington (northwest U.S.A.). These sediments have been contaminated to varying degrees by hydrocarbons from a creosote plant and from various combustion sources. PAH were not detected in pore waters of sediments whose PAH were primarily derived from combustion and natural sources, even though pore water concentrations predicted from sediment concentrations and two-phase equilibrium partitioning models were above detection limits from most PAH. Equilibrium partition coefficients calculated from field aqueous and solid phase data from an area contaminated with creosote agreed with laboratory-derived coefficients to within a factor of ± 4. Pore water concentrations of creosote-derived aliphatic hydrocarbons increase with increasing concentration in bulk sediments. However, pore water concentrations of natural and contaminant aliphatic hydrocarbons are much higher than predicted by solubility data, possibly due to association with nonfilterable dissolved organic matter and colloids. Other major factors controlling hydrocarbon pore water concentrations include differential hydrocarbon sources, specific particle associations and solubility.     

Polycyclic aromatic hydrocarbons in the soils of technogenic landscapes

An integrated study of qualitative and quantitative composition of polycyclic aromatic hydrocarbons (PAH) in the atmospheric precipitation-soil-lysimetric water system of aerotechnogenic polluted landscapes was conducted using high-performance liquid chromatography in a gradient mode. Only low-molecular weight polyarenes (phenanthrene, anthracene, fluoranthene, pyrene, benz(a)anthracene, and chrysene) were found in the atmospheric precipitation and lysimetric waters. The growth of PAHs in soils is provided by the input of phenanthrene, fluoranthene, and pyrene with atmospheric precipitation. The absence of heavy PAHs (benzfluoranthenes, benz(a)pyrene, dibenz(a,h)anthracene, benz(ghi) perylene, and indeno[1,2,3-cd]pyrene) in the atmospheric precipitation and their identification in soil give grounds to state that their accumulation was caused mainly by transformation of organic matter during pedogenesis. The technogenic impact was estimated and criterion of the degree of soil pollution by PAH was proposed.     

Polycyclic aromatic hydrocarbons as evidence of hydrocarbon migration in marine and lagoon sediments of a recent rift zone (Skjálfandi and Öxarfjörður), Iceland

Polycyclic aromatic hydrocarbons (PAHs) content and distribution was studied in the northern part of modern rift zone. All samples analysed represent slightly altered clastic deposits and hot water discharging in springs and from wells. To study PAH in present-day gas emission traps with diatomite absorbent were installed in the Skógalón geothermal field. All samples were analysed by the method of Shpol'sky spectroscopy. Hydrothermally altered deposits show the highest amount of PAH. Data obtained allow to believe that the distribution of PAH is closely associated with the dynamics of the hydrothermal environment. The fissure formation and temperature fluctuation in hydrothermal systems can govern both the processes of PAH synthesis and sorption. The evidences of PAH migration up through the Skjálfandi and Öxarfjörður sedimentary basins show that hydrocarbons associate mainly with hydrothermal minerals and deep ground waters. Studying PAH associations can be used as an indicator of hydrocarbons distribution, ways of migration and possible zones of accumulation in the land and marine sedimentary basins in active and ancient rift zones of Iceland.     

Hydrogeochemistry and transport of organic contaminants in an urban watershed of Chesapeake Bay (USA)

Stream water samples were collected in the two main free-flowing branches of the Anacostia River watershed above the head of tide over a one year time period. Both the Northeast and Northwest Branches drain large suburban and urban land areas that flow into the more urbanized tidal portion of the Anacostia River within Washington, DC. Large volume (40–75 l) water samples were filtered, and the suspended particulate matter and filtrate were analyzed for polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and organochlorine pesticides (OCPs) at sub-nanogram per liter concentrations using ultra-trace analytical methods. Higher amounts of PCBs, PAH, and OCPs in the tidal Anacostia River occurred primarily in the particulate phase during high flow events. Polycyclic aromatic hydrocarbons in the particulate phase within fluvial transport consisted primarily of pyrogenic homologues characteristic of weathered or combusted petroleum products. Fluxes were exceptionally high for PAHs which showed annual fluxes to the tidal Anacostia River comparable to those determined for the much larger mainstem Potomac River. Aromatic hydrocarbons in runoff from urban regions may serve as an important source of PAH fluxes to the tidal waters of Chesapeake Bay.     

Risk assessment of polycyclic aromatic hydrocarbons in the West Port semi-enclosed basin (Malaysia)

Sediment samples collected from the West Port, the west coastal waters of Malaysia, were analyzed by standard methods to determine the degree of hydrocarbon contamination and identify the sources of polyaromatic hydrocarbons (PAHs). Concentrations of PAHs in the port sediments ranged from 100.3 to 3,446.9 μg/kg dw. The highest concentrations were observed in stations close to the coastline, locations affected by intensive shipping activities and industrial input. These were dominated by high-molecular-weight PAHs (4–6 rings). Source identification showed that PAHs originated mostly pyrogenically, from the combustion of fossil fuels, grass, wood, and coal or from petroleum combustion. Regarding ecological risk estimation, only station 7 was moderately polluted, the rest of the stations suffered rare or slight adverse biological effects with PAH exposure in surface sediment, suggesting that PAHs are not considered as contaminants of concern in the West Port.     

The polycyclic aromatic hydrocarbon concentrations in soils in the Region of Valasske Mezirici, the Czech Republic

The polycyclic aromatic hydrocarbon (PAH) contamination of urban, agricultural and forest soil samples was investigated from samples obtained in the surroundings of Valasske Mezirici. Valasske Mezirici is a town located in the north-east mountainous part of the Czech Republic, where a coal tar refinery is situated. 16 PAHs listed in the US EPA were investigated. Organic oxidizable carbon was also observed in the forest soils. The PAH concentrations ranged from 0.86-10.84 (with one anomalous value of 35.14) and 7.66-79.39 mg/kg dm in the urban/agricultural and forest soils, respectively. While the PAH levels in the urban/agricultural soils are within the range typically found in industrialized areas, the forest soils showed elevated PAH concentrations compared to other forest soils in Western and Northern Europe. The PAH concentrations and their molecular distribution ratios were studied as functions of the sample location and the meteorological history. The soils from localities at higher altitudes above sea level have the highest PAH concentrations, and the PAH concentrations decrease with increasing distance from the town.     

The role of zooplankton fecal pellets in the sedimentation of polycyclic aromatic hydrocarbons in Dabob Bay,Washington

Polycyclic aromatic hydrocarbon (PAH) compositions were determined in plankton, sediment-trap-collected particulate material and sediment cores from Dabob Bay using a high performance liquid Chromatographie (HPLC)/fluorescence technique. The annual flux of individual PAH measured in a series of sediment traps was compared with the flux of corresponding compounds determined from ²¹⁰Pb dated bottom sediments. Systematic seasonal variations in the fluxes and concentrations of PAH, Al and organic carbon in the trap-collected particulates and seasonally collected plankton were also investigated to determine whether or not PAH are associated with either terrestrial or marine-derived materials.Concentrations of all PAH studied increased tenfold within the last 80–100 yr of sediment deposition, except for perylene which displayed a reasonably constant concentration profile. This suggests at least two sources contribute to the observed sedimentary PAH compositions in Dabob Bay, i.e., anthropogenic combustion and a natural source. Plankton and sediment trap-collected particulates contained PAH mixtures qualitatively similar to underlying surface sediments. Microscopic examination indicated fecal pellets were the major form of particulate material in the sediment traps. The fecal pellets collected in the sediment trap time series quantitatively account for essentially 100% of the PAH fluxes measured in the ²¹⁰Pb dated sediments, implying Zooplankton fecal pellets control the removal of PAH to Dabob Bay sediments. These measurements provide clear evidence that the PAH studied are not produced after sediment deposition. The observed seasonal covariations of PAH and Al in both sediment trap and plankton samples further indicate that PAH originate from terrestrially-based sources, are introduced into the marine environment by runoff and erosion or atmospheric deposition and are not produced by marine plankton.     

Fluxes of polycyclic aromatic hydrocarbons to marine and lacustrine sediments in the northeastern United States

Polycyclic aromatic hydrocarbons (PAH) were measured in dated sediment cores from several sites in the northeastern United States (Lake Superior, Isle Royale, Somes Sound, Hadlock Lower Pond. Coburn Mountain Pond, and outer Boston Harbor). Fluxes of ten PAH were measured for each site for the periods roughly corresponding to the present, 1950, and 1900. Remote sites consistently demonstrated present-day deliveries of individual PAH near 1 ng cm^?2 yr^?1, probably reflecting the atmospheric fallout of these combustion-derived pollutants. Sites located nearer to urban centers showed much greater current inputs (average of 35 ng cm^?2 yr^?1 for most individual PAH), presumably caused by greater fallout of PAH-laden particles nearer their urban origins, augmented by runoff delivery of PAH-contaminated sediments. Differences in the relative abundances of individual PAH at remote-versus-urban locations support suggestions of different delivery mechanisms. The sedimentary historical records of PAH inputs confirm the previous finding that anthropogenic activities began introducing large quantities of PAH into the environment about 80–100 years ago.     

Effects of physical mixing on the attenuation of polycyclic aromatic hydrocarbons in estuarine sediments

To examine the role of physical disturbance on the long-term preservation of polycyclic aromatic hydrocarbons (PAHs) in sediments, cores were collected from two sites removed from point sources of PAHs and representing contrasting seabed mixing regimes. Although ΣPAH concentrations in sediments over the past 50 years were not significantly different between the two sites, several PAH isomer ratios were significantly different (P<0.05) between the two sites. Downcore changes in PAH isomer ratios resulted from preferential losses of the more linear PAH isomers. Thus, episodic, intense seabed mixing contributes to more efficient removal of selected PAHs. However, PAHs are still sufficiently stable relative to mixing events that historical PAH profiles can be used to reconstruct major resuspension events.     

环境中的多环芳烃及其生物恢复技术

多环芳烃是一大类广泛存在于环境中的有机污染物。天然燃烧、火山爆发、矿物资料及其它有机物的不完全燃料和热解产生的PAH进入大气中，气态沉降、城市地表径流、城市污水、废水及油的溢涵和渗漏等是PAH进行地表水的主要途径，大气中PAH的干、湿沉降，污水灌溉，地面及地下储油装置的渗漏，地面固体废物堆的淋滤等是土壤中PAH的主要来源，沉积物和土壤是PAH的主要环境归宿。生物恢复是一种处理有机污染的新方法。     

Historical record of polycyclic aromatic hydrocarbons (PAH) and heavy metals in floodplain sediments from the Rhine River (Hessisches Ried, Germany)

The depth-related content of polycyclic aromatic hydrocarbons (PAH) and heavy metals was determined for two soil profiles (i.e. one Fluvisol and one Gleyic Cambisol) which developed in sediments from floodplains located at an old meander of the Rhine river. The meander had been cut off from the main river in 1829. The separation of the meander from the main river caused a change in sediment deposition (i.e. from sand to silt) which is clearly visible in the soil-profiles. Since that time, approximately 100 cm of sediments have accumulated due to temporary flooding of the area. Each soil profile was separated into 18 samples. The samples were analysed for their content of PAH after solvent extraction. Additionally, several trace elements (Co, Ni, Cd, Pb, Zn, Cr and Cu) were determined in the same sample set, and depth-related concentration profiles for both PAH and trace elements were developed. The distribution patterns of PAH with more than 3 condensed rings did not provide any evidence for PAH biodegradation or vertical transport after deposition of the sediments. Thus, in the case of PAH, the historical record can be derived not only from subhydric sediments but also from floodplain sediments. It was not possible to distinguish between atmospheric and fluvial input of PAH into the sediments from the observed distribution patterns due to the same origin of PAH from pyrolytic processes. A source determination of the PAH was not possible except for perylene, for which biogenic formation can be assumed. A comparison of the results shows that the depth-related PAH and trace element concentrations display similar trends over most of the total profiles. In the uppermost section of the profiles, the concentration of most trace elements declines whereas the PAH concentration remains high. This indicates the presence of different sources for PAH and trace elements in the last decades.     

Hydrocarbons in the water and bottom sediments of a region with continuous petroleum contamination

The abundances and compositions of aliphatic hydrocarbons (AHC) and polyaromatic hydrocarbons (PAH) were investigated in the water and bottom sediments of the southwestern Amur Bay in the Sea of Japan. The water contained from 0 to 129 μg/1AHC (averaging 42.2 μg/l) and from 5 to 85 ng/l PAH (averaging 18 ng/l). The bottom sediments contained 168–2098 μg/g AHC and 7.2–1100 ng/g dry mass PAH. It was shown that the input of anthropogenic HC is better recorded by molecular markers than the distribution of AHC and PAH concentrations. The discovery of elevated HC concentrations in the bottom water layer suggests that the bottom sediments induced secondary contamination of the water body.     

Polycyclic aromatic hydrocarbons in an anoxic sediment core from the Pettaquamscutt River (Rhode Island,U.S.A.)

Fifteen sections from an anoxic sediment core were analyzed for polycyclic aromatic hydrocarbons (PAH). Two types of PAH were observed: (a) those from combustion sources such as pyrene and chrysene and (b) those from natural sources such as retene and perylene. The combustion PAH levels in core sections dated between 1900 and 1970 were much higher than in earlier sections; this indicated an anthropogenic origin of these PAH at this location. The perylene and retene core profiles show significant anomalies during the period 1850–1880. Organic carbon does not fluctuate markedly but δC-13 of organic carbon shows several unexplained excursions; one of which correlates with the perylene and retene anomalies.     

Distribution of hydrocarbons in the estuarine area of the Northern Dvina River during seasonal flood

Heavy contaminant load released into the Northern Dvina River during flooding increased the concentrations of aliphatic (AHC) and polcyclic aromatic (PAH) hydrocarbons in water and bottom sediments. The composition of hydrocarbons was different from that of the summer low flow season. The concentrations of dissolved and particulate AHC ranged from 12 to 106 and from 192 to 599 μg/l, respectively, and bottom sediments contained from 26.2 to 329 μg/g AHC and 4 to 1785 ng/g PAH. As the transformation of AHC occurred at low spring temperatures, the alkane composition was shown to be dominated by terrigenous compounds, whereas more stable PAH showed elevated contents of petrogenic and pyrogenic compounds. It was also shown that the Northern Dvina-Dvina Bay geochemical barrier prevents contaminant input into the White Sea, i.e., acts as a marginal filter.     

The global distribution of polycyclic aromatic hydrocarbons in recent sediments

Polycyclic aromatic hydrocarbons (PAH) and their alkyl homologs are distributed in sediments throughout the world. The qualitative PAH pattern is remarkably constant for most of the locations studied, and the quantitative PAH abundance increases with proximity to urban centers. These findings are consistent with anthropogenic combustion's being the major source of these compounds. Two non-combustion sources of PAH have also been noted: retene coming from abietic acid and perylene probably coming from various extended quinone pigments.     

High molecular weight polycyclic aromatic hydrocarbons in hydrothermal petroleums from the Gulf of California and Northeast Pacific Ocean

Hydrothermal petroleums and heavy tars have been analyzed for polycyclic aromatic hydrocarbons (PAH) with molecular weights greater than that of coronene (300 da). Samples from the hydrothermal systems in the Guaymas Basin (Gulf of California) and in the Escanaba Trough and Middle Valley (Northeastern Pacific) were analyzed by gas chromatography-mass spectrometry and high pressure liquid chromatography with diode-array absorbance detection. Mass spectra and fluorescence spectra were used to characterize the compounds. Several large PAHs with six and more rings were identified among the heavy PAH. Production routes via one-ring build-up and Scholl-condensation are proposed to explain the observed structures. The variations in PAH concentrations and distributions between samples from different locales are a consequence of the hydrothermal conditions of generation, migration, and post-depositional alteration.     

Urban and rural limestone weathering; the contribution of dust to black crust formation

A novel approach of studying dust, black crust and host limestones by using various techniques is presented in this paper. Samples were collected from limestone monuments located in rural, urban and industrial areas in Germany and Hungary. The paper focuses on differences in the mineralogical composition, major and trace element distribution of materials and their total polyaromatic hydrocarbons (PAH) concentration having different exposure to air pollutants. High concentration of gypsum was found in laminar and dendritic black crusts and even in the dust of both urban and rural areas, despite the low concentration of SO₂ in rural atmospheric environments. The black crusts show a typical microfabric with distinct layers of various gypsum–calcite mineral associations, silt-sized mineral fragments and black particle content. In dust, newly formed gypsum crystals were found along with mineral fragments, and siliceous and, less frequently, carbonaceous fly ash particles. High concentration of lead was found both in the samples of urban and rural areas of Germany and Hungary. Lead mostly accumulates in dust and also in the black crust. Highest lead concentrations were found not on the surface of the black crust, but close to the crust/limestone boundary according to LA-ICPMS analyses. It indicates that despite the ban of leaded petrol, lead is still present in the dust and the in the soiled zones of the built environment. Similarly to lead, no significant difference in the total PAH content of dust and crust samples were found in the two countries. Dusts are equally enriched in PAH in both countries, whereas black crusts contain fewer amounts. Most of the aqueous extracts of the samples were saturated with respect to sulphate, which also indicate the presence of gypsum, whilst in some German samples unsaturated conditions were detected. In summary, by using a combination of these analytical techniques, it was possible to distinguish rural and urban samples and to outline the role of dust in bringing pollutants to the stone surface. It is suggested that the analysed dust and stone samples indicate not only present, but also the past, pollution fluxes and as a consequence stones similar to sediments or surface waters can be used as environment indicators.     

Polycyclic aromatic hydrocarbons in Recent lake sediments—I. Compounds having anthropogenic origins

Polycyclic aromatic hydrocarbons (PAH) in sediment cores from Lake Lucerne, Lake Zürich, and Greifensee, Switzerland, and Lake Washington, northwest U.S.A., have been isolated, identified and quantified by glass capillary gas chromatography and gas chromatography/mass spectrometry. Surface sediment layers are greatly enriched in PAH—up to 40 times—compared to deeper layers. In addition, concentration increases in upper sediments generally correspond to increasing industrialization and urbanization in the catchment basins of the lakes. Few PAH could be detected in pre-industrial revolution sediments, indicating that background levels for most PAH in aquatic sediments are extremely low.These results are consistent with an anthropogenic source for most of the aromatic hydrocarbons present in the modern sediments. A comparison of PAH distributions in the sediments and in possible source materials shows that urban runoff of street dust may be the most important PAH input to these lacustrine sediments. There is evidence that a significant contribution to the PAH content of street dust comes from material associated with asphalt.