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1.
The burial characteristics and toxicity risks associated with n-alkanes and polycyclic aromatic hydrocarbons (PAHs) in the riverine and estuarine sediments of the Daliao River watershed were investigated based on three sediment cores. The sum of the n-alkane and PAH concentrations, normalized to organic carbon (OC), ranged from 0.27 to 63.09 μg g?1OC?1 and 6.60 to 366.20 μg g?1OC?1, respectively. The features and the history of industrial activities, such as the oil and chemical industries and port activities near the river and estuary, resulted in different distributions and sources of hydrocarbons. The sources of pollution were identified based on n-alkane indexes and on diagnostic ratios of PAHs. The diagnostic ratios indicated that the n-alkanes were derived from both biogenic and petrogenic sources in different proportions and that the PAHs were derived primarily from petrogenic combustion sources. A hierarchical cluster analysis grouped the core samples into two clusters. The first cluster, river sediments, corresponded to industrial activities; the second cluster, estuarine sediments, corresponded to port shipping activities. The toxic potency of the PAHs in the cores was assessed in terms of toxic equivalents (TEQs) of dibenzo[a,h]anthracene and benzo[a]pyrene. The top layer of the sediment in the cores had a relatively high toxicity. The TEQ values for benzo(a)pyrene (TEQBaP) and dioxins (TEQTCDD) furnished a consistent assessment of the PAHs in the sediment cores.  相似文献   

2.
Concentrations, spatial distribution and sources of 16 polycyclic aromatic hydrocarbons (PAHs) listed by the United States Environmental Protection Agency as priority pollutants were investigated in surface sediments of Bohai Bay, North China. Total concentrations of PAHs were in the range of 140.6–300.7 ng/g (dry wt), with an average of 188.0 ng/g. The three predominant PAHs were phenanthrene, acenaphthene and naphthalene. Sedimentary PAH concentrations of the north and central Bohai Bay were higher than those of the southern side of this bay. PAHs source analysis suggested that PAHs in most of the sediments were mainly from grass, wood and coal incomplete combustion. At other stations near the estuaries (Luanhe River Estuary and Chaohe River Estuary) or the oil drilling platform, both petrogenic and pyrogenic inputs were significant. The pyrogenic PAHs close to the oil drilling platform were mainly from petroleum combustion.  相似文献   

3.
Suspended particle samples from the Yellow River estuary were sorted into five grain size fractions to explore the effect of grain size distribution on organic matter content and composition. The n-alkanes and PAHs were determined for each size fraction. PAHs and n-alkanes were more abundant in the finer fractions and the loading decreases steadily with increasing of grain size. However, the total n-alkanes or PAHs normalized to organic C were lower in the smaller size fractions than those in the larger size fractions, suggesting n-alkanes or PAHs may be diluted by the addition of organic matter or gradually decreased by degradation in the smaller size fractions. The particulate n-alkanes in the Yellow River estuary consist of a mixture of compounds from terrigenous and riverine biogenic n-alkanes and more biogenic n-alkanes accumulate in finer particles. Particulate PAHs are related to combustion/pyrolysis processes of coal/wood, and the relative contribution of petrogenic PAHs increase with increasing grain size. The total particulate n-alkane and PAH discharges passing the Lijin Station are about 3.94 t d−1 and 0.52 t d−1, respectively. Fine particles (<32 μm) play a significant role in organic matter transfer.  相似文献   

4.
Attention has been paid for the levels, sources and health risks of atmospheric aliphatic and polycyclic aromatic hydrocarbons (n-alkanes and PAHs) in remote areas, however, few studies have focused on those in the Tibetan Plateau. In this study, 18 pairs of atmospheric samples were obtained during the period from August 2006 to July 2007 in Lhasa, the capital city of Tibet. Both gas-phase and particulate-phase n-alkanes and PAHs were measured. Concentrations of n-alkanes (gas + particulate phase, 99.1–480.9 ng/m3) and PAHs (gas + particulate phase, 11.4–72.5 ng/m3) in Lhasa are lower than those in many cities. The sources of n-alkanes related to biological and petroleum sources were 67 and 33%, respectively. According to the results of diagnostic ratios and principal component analysis, emission of traffic vehicles was one of the important PAH sources, and sources of benzo(a)pyrene was likely attributed to incense burning. Good simulations were obtained by traffic soot-based model for fluoranthene, pyrene and benzo(a)anthracene, while, wood soot-based model fitted the experimental results of benzo(a)pyrene better. This meant atmospheric fate of PAHs was mainly influenced by the adsorptive partitioning that occurred during traffic and incense burning procedures. In addition, the benzo[a]pyrene-equivalent carcinogenic power (BaPE) in the present study (0.1–1.6 ng/m3) is lower than those in other cities and also the air quality standard of China, suggesting that atmospheric PAHs caused low health risks.  相似文献   

5.
Oyster and sediment samples collected from six sites in Galveston Bay from 1986 to 1998 were analyzed for polynuclear aromatic hydrocarbons (PAHs). Total concentrations of parent PAHs in oysters ranged from 20 ng g−1 at one site to 9,242 ng g−1 at another and varied randomly with no clear trend over the 13 year period at any site. Concentrations of alkylated PAHs, which are indications of petroleum contamination, varied from 20 to 80,000 ng g−1 in oysters and were in higher abundance than the parent PAHs, indicating that one source of the PAH contaminants in Galveston Bay was petroleum and petroleum products. Four to six ring parent PAHs, which are indicative of combustion source , were higher than those of 2–3 ring parent PAHs, suggesting incomplete combustion generated PAHs was another source of PAHs into Galveston Bay. Concentrations of parent PAHs in sediments ranged from 57 to 670 ng g−1 and were much lower than those in oysters. Sediments from one site had a high PAH concentration of 5,800 ng g−1. Comparison of the compositions and concentrations of PAHs between sediment and oysters suggests that oysters preferentially bioaccumulate four to six ring PAHs. PAH composition in sediments suggests that the sources of PAH pollution in Galveston Bay were predominantly pyrogenic, while petroleum related PAHs were secondary contributions into the Bay.  相似文献   

6.
This is a comprehensive study of the composition, origin and sources of specific polycyclic aromatic hydrocarbons (PAHs) in sediments of mangrove estuary in the western part of Peninsular Malaysia. Mangrove sediments were analyzed for 17 PAHs by gas chromatography–mass spectrometry. Total PAH concentrations in the sediments ranged from 20 to 112 ng/g on a dry-weight basis. High molecular weight PAHs were abundant in the sediments. Parent PAH ratios revealed that pyrogenic input has important contribution to the sedimentary PAHs. Ratios of alkylated PAHs indicate that the sedimentary PAHs were influenced by petrogenic PAHs, which implies that petrogenic input has contribution to the sedimentary PAHs but that it is not a major factor in distribution of PAHs within the estuary. Combustion-derived PAHs show a positive and very strong correlation with total PAHs (R 2 = 0.926, p < 0.05). Total methylphenanthrenes show very weak correlation with total PAHs (R 2 = 0.0928, p < 0.05). The PAH concentrations were found to increase with distance from the upstream of the estuary to the coastal area of the Straits of Malacca. For the assessment of sediment contamination using biological thresholds, none of the individual studied PAH compounds exceeded the values of the effect range low–effect range median guideline and the threshold effects level–probable effects level guideline. This study demonstrates that the sediments of the mangrove ecosystem facing the Straits of Malacca and Sumatra are influenced by anthropogenic PAH inputs as a result of human activities such as biomass burning, vehicle emissions and boating activities.  相似文献   

7.
The present work is the first attempt to compare the data of a comprehensive study of the origin and distribution of 16 priority pollutant polycyclic aromatic hydrocarbons (PAHs) in surface sediments (<63 μm) from 18 sampling stations, 9 from Sundarban of Bangladesh and 9 from Indian counterpart. Σ19PAHs concentration in sediments showed wide variations from 208.3 to 12,993.1 ng g?1 dry weight in Indian Sundarban, whereas 208.4 to 4,687.9 ng g?1 in the case of Bangladesh. Fluoranthene, pyrene, benzo(b)fluoranthene, benzo(a)pyrene and dibenzo(a,h)anthracene were predominant species for both the countries. The PAH diagnostic ratios indicated that the PAHs in sediments from both the countries were of mixed source of hydrocarbons of both petrogenic and pyrolytic origin. According to the numerical effect-based sediment quality guidelines, the levels of PAHs in the Sundarban wetland of Bangladesh and India should not exert adverse biological effects. The TEQ values calculated for samples from the Bangladesh and Indian Sundarban varied from 13.68 to 1,014.75 and 1.31 to 2,451 ng g?1 d.w. with an average of 221.02 and 358.63 ng g?1, respectively. The overall contamination status of PAH was higher in India than Bangladesh.  相似文献   

8.
《Applied Geochemistry》2001,16(11-12):1429-1445
Polycyclic aromatic hydrocarbons (PAHs) were measured in surface sediments and dated core sediments from the Pearl river and estuary, China, to investigate the spatial and temporal variability of anthropogenic pollutants. The sediments from the sampling stations at the Guangzhou channel have the highest concentrations of PAHs, owing to contributions from the large amount of urban/industrial discharges from the city of Guangzhou. The significant decrease of PAHs concentrations in sediments from the Shiziyang channel is mainly attributed to the increasing degradation and desorption of low molecular weight PAHs and alkyl PAHs, and the dilution by less contaminated water and particles from the East river. The PAH contaminants were concentrated on the western side in the Lingding bay of the Pearl river estuary because of the hydrodynamic and sedimentation conditions. Based on the characteristics of the parent compound distributions (PCDs) and the alkyl homologue distributions (AHDs) of PAHs, the potential source of PAHs in sediments from each sampling station was identified. Results indicated that the pyrogenic (combustion) source, characterized by the abundance of parent PAHs, were predominant in the heavily contaminated station (ZB01) near the aging industrial area, and the petrogenic (petroleum- derived) PAHs were more abundant in the stations (ZB02, ZB03) adjacent to the petrochemical plant and shipping harbor. Sediments from Lingding bay show variable distributions of PAH composition and variety in the proportion of combustion and petrogenic sources for the PAHs in different stations. Perylene, a naturally derived PAH, was found to be highly abundant in less contaminated stations. Analysis of the dated sediments (210Pb) indicates that higher PAH concentrations occurred in the sediments deposited after 1980, and higher fluxes of PAHs discharged to the Pearl river are found after 1990.  相似文献   

9.
We present the first sedimentary biomarker study encompassing the entire Arctic Ocean. A large data set of organic markers for terrigenous, petroleum and combustion inputs [alkanes, hopanes and steranes, parent and alkyl polycyclic aromatic hydrocarbons (PAHs)] is examined for patterns in space and time using principal components analysis (PCA) and partial least squares (PLS). Biomarker patterns reveal the central Arctic Ocean basin sediments to be compositionally distinct from those of the Mackenzie River/Beaufort Sea and Barents Sea, but similar to those of the Laptev Sea. PAH distributions reflected in PAH ratios and PCA projections demonstrate that Arctic Ocean sediment is dominated by natural inputs to the extent that anthropogenic combustion PAHs are not significant. We find only modest changes between the glacial and post-glacial sediments for atmospherically transported hydrocarbon biomarkers, while particle associated biomarkers were captured strongly at basin edges during the glacial period, and much more evenly transported across basins during the post-glacial period. The orders of magnitude decreases in particle associated petrogenic alkanes and PAHs in central basins during glacial times, coupled with the uniformity of most petrogenic biomarker parameters for most basin and shelf locations, reflect a massive reduction in ice transport that makes the margins the most likely source of petrogenic material for the Pleistocene/Holocene central Arctic basins. The proximity of large coal deposits of various maturity levels along the Lena River, the overlap in PAH and biomarker composition of the Laptev Sea and surficial sediments from the central Arctic Ocean and the location of the Laptev Sea at the origin of the main Transpolar Drift all point to eroded coals from the Lena River/Laptev Sea as the likely source of petrogenic hydrocarbons to the central Arctic Ocean. The ubiquitous presence of allochthonous coal in Arctic Ocean surface sediments provides a major constraint on the use of petrogenic biomarkers to infer the presence of subsurface petroleum reserves.  相似文献   

10.
Soil samples were collected at different locations from Etche and Obio Akpor local government area (LGA) of River State in Niger Delta. The n-alkane and polycyclic aromatic hydrocarbons were determined qualitatively and quantitatively using GC-FID. The concentration of PAHs in the soil samples ranged from 7.40 to 78.3 ng/g. The highest concentration of PAHs was recorded in Agbada 1 flow station, while the lowest concentration was recorded in Agbada 2 flow station. A significant level of pollution was also observed in the soil of Bomu pipeline at Obio Akpor LGA. Also, the distribution of n-alkanes in the samples was also used to assess the level of pollution in the studied area. Various n-alkanes and PAHs ratios were obtained to know the major source of pollution in the area under study. The main source of pollution was pyrolytic, which might be due to the gas flaring activities going on in the study area. Also, the results showed that n-alkanes could also be a complementary tool in assessing pollution and source apportionment.  相似文献   

11.
Sediment samples collected from the Core Area, Experimental Area and Buffer Area of Yellow River Delta National Nature Reserve (YRDNNR), China, were analyzed by GC-MS in order to determine the degree of hydrocarbon contamination, and identify the sources of aliphatic hydrocarbons and PAHs. The total petroleum hydrocarbon contents of sediments were relatively low or moderate compared to world-wide locations reported to be chronically contaminated by oil. On the whole, the degree of petroleum contamination in the Core Area and Buffer Area in YRDNNR is weaker than that of the Experimental Area. The potential ecosystem risk assessment indicated that PAHs will not cause immediate adverse biological effects in the YRDNNR. Besides oil-related hydrocarbon inputs in this region, aliphatic hydrocarbon analysis showed the presence of hydrocarbons of terrestrial origin at some sampling sites, characterized by high CPI values. Based on PAH ratios and principal component analysis, pyrolytic input may be a major source of PAHs in YRDNNR sediment, while petrogenic inputs were more apparent at some sites in the Experimental Area due to oil exploration in the Shengli Oilfield.  相似文献   

12.
Simultaneous mass spectral detection and stable carbon isotope analysis was performed on individual indigenous n-alkanes isolated from single C4 and C3 plant species and on a series of aliphatic and polycyclic aromatic hydrocarbons (PAH) produced from the combustion of these same biomass materials. The analysis technique used a combined gas chromatograph-mass spectrometer/combustion/isotope ratio mass spectrometer (GC-MS/C/IRMS). Precision (2σ) for replicate measurements of individual compounds in standard solutions using this novel configuration ranged between 0.2 and 0.5‰ for n-alkanes and 0.3 and 0.8‰ for PAH. Accuracy of the n-alkane measurements ranged between 0.1 and 0.4‰ and that of the PAH measurements ranged between 0.2 and 0.9‰. Replicate GC-MS/C/IRMS measurements on the combustion-derived n-alkene/alkane pairs were performed to within a precision of between 0.1 and 1.1‰ and the precision for the combustion PAH was similar to the standard PAH solution. No notable isotopic effects were observed when altering the temperature of the combustion process from 900 to 700°C, or as a result of the individual n-alkenes/alkanes partitioning between the gaseous and condensate fractions. Combustion-derived n-alkenes/alkanes ranged from C11 to C31, and the C4-derived n-alkenes/alkanes were approx. 8‰ more enriched in 13C than the C3-derived compounds. Both the C4 and C3-derived n-alkenes/alkanes (C20-C30) were isotopically similar to the indigenous n-alkanes and were 2-3‰ more depleted in 13C than the lower mol. wt (C1111-C19) n-alkenes/alkanes, suggesting an independent origin for the lower mol. wt compounds. Combustion-generated C4 and C3-derived 2-, 3-, and 4-ring PAH were also isotopically distinct (Δδ = 10‰). Unlike the n-alkenes/alkanes, no compound-to-compound variations were observed between the low and high mol. wt PAH. This study demonstrates that the isotopic composition of original plant biomass material is mainly preserved in the aliphatic hydrocarbons and PAH generated by its combustion. Consequently, analyses of these compounds in sediments impacted by fire occurrences may provide useful information about paleo-fire activity that may help elucidate the impact biomass burning may have had and could have on climate-biosphere interactions.  相似文献   

13.
The sources and historical deposition of 16 polycyclic aromatic hydrocarbons (PAHs) were investigated in dated sediment cores from the Pichavaram mangrove–estuarine complex. The ΣPAH flux in mangrove and estuarine sediments was 0.064 ± 0.031 μg/cm2/yr and 0.043 ± 0.020 μg/cm2/yr, respectively. The PAH flux in sediments increased up-core, coinciding with rapid urbanization since the 1970s. The flux showed a decrease in recent years (since 1990), coinciding with less riverine discharge, and perhaps more effective implementation of environmental regulations. The sediments were dominated by low molecular weight PAHs, suggesting anthropogenic input. Ratios of specific PAH isomer pairs suggested a greater input of petrogenic vs. pyrogenic derived PAHs. Notably, the deposition of high molecular weight PAHs increase in mangrove surface sediments was due to lignite and firewood combustion. Because of their overall low concentration in sediments it is unlikely these PAHs pose an immediate ecological hazard.  相似文献   

14.
Concentration, distribution, and sources of 16 polycyclic aromatic hydrocarbons (PAHs) were investigated in surface sediments of Laizhou Bay, China. Total PAH concentrations ranged from 97.2 to 204.8 ng/g, with a mean of 148.4 ng/g. High concentrations of PAHs were found in the fine-grained sediments on both sides of the Yellow River estuary (YRE). In contrast, low levels of PAHs were observed in relatively coarse grain sediments, suggesting hydrodynamics influence the accumulation of sedimentary PAHs. The YRE and its adjacent area is the main sink for Yellow River-derived PAHs. Both PAH isomer ratios and principal component analysis (PCA) with multivariate linear regression (MLR) were applied to apportion sources of PAHs. Results indicated that both pyrogenic and petrogenic PAH sources were important. Further PCA/MLR analysis showed that the contributions of coal combustion, petroleum combustion and a combined source of spilled oil and biomass burning were 41, 15 and 44%, respectively. From an ecotoxicological viewpoint, the studied area appears to have low levels of PAH pollution.  相似文献   

15.
Hydrocarbon compositions have been determined for 210Pb-dated sediment cores collected at 23 sites within the inland marine waters of northwestern Washington State, U.S.A. Concentrations of total aliphatic hydrocarbons (TAH) and an unresolved complex mixture (UCM) are significantly higher in surface sediments near urban areas than at all other locations with a chronology that indicates a predominantly anthropogenic origin. Concentrations of chromatographically resolvable alkanes are comparatively uniform; the major constituents are plant wax n-alkanes and a naturally-occurring suite of fossil isoprenoid and n-alkanes. Pristane concentrations decrease sharply near the sea-sediment interface suggesting rapid degradation of a plankton-derived component. A saturated multibranched, but nonisoprenoid, C20 hydrocarbon and two novel mono-olefinic analogs have been isolated along with a previously unreported suite for four acyclic multibranched C25 polyenes. Structural and distributional similarities between the C20 and C25 multibranched hydrocarbons suggest that they may be structurally homologous and share a common source.  相似文献   

16.
Surface sediments from the Outer Continental Shelf of Alaska were analyzed for hydrocarbons as part of an environmental survey sponsored by NOAA/BLM. Sediments were collected from the proposed oil lease areas of Beaufort Sea, southeastern Bering Sea, Norton Sound, Navarin Basin, Gulf of Alaska, Kodiak Shelf and lower Cook Inlet. Data on normal and branched alkanes and di- and triterpenoids from capillary gas chromatography (GC) and gas chromatography-mass spectrometry (GC/ MS) indicate that the area displays little evidence of petroleum hydrocarbons (i.e., seeps) except at a few isolated stations. Beaufort Sea sediments have the highest hydrocarbon budget, whereas Kodiak Shelf sediments have the lowest. The molecular markers of the hydrocarbons are of a mixed marine autochthonous and terrestrial allochthonous origin. Norton Sound and Cook Inlet sediments contain the highest levels of terrigenous lipids and Kodiak Shelf the lowest. The abundance of alkenes implies that relatively low oxidizing conditions exist in some of the depositional areas studied, suggesting that extraneous petroleum hydrocarbons introduced into these sediments would be expected to have a relatively long residence time. The distribution of polynuclear aromatic hydrocarbons (PAH) is complex and shows a pyrolytic origin. The data on perylene strongly favor the hypothesis that it is “performed” from terrigenous precursors and transported into the marine environment with no apparent in situ generation. Polynuclear aromatic hydrocarbons of diagenetic origin are probably dominant in Gulf of Alaska and Kodiak Shelf sediments.Two stations, north of Kalgin Island, in lower Cook Inlet and one in southeastern Bering Sea show typical weathered petroleum distribution of n-alkanes and triterpenoids. Probable pathways of transport and fate of petroleum hydrocarbons in case of an oil spill are also briefly discussed.  相似文献   

17.
Concentrations of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were measured in 13 surficial sediment samples collected at three lacustrine locations in the surroundings of Mexico City and four coastal areas of the States of Sinaloa, Sonora, Oaxaca and Veracruz. Total PCB concentrations span the interval 3.18–621 ng g−1. The highest values (63.7–621 ng g−1) were found in Mexico City, which is a highly anthropogenically impacted area, whereas low concentrations (3.18–12.9 ng g−1) were characteristic of seven places, some of them subject to intense hydrodynamics. In these latter cases, values increase by 18–73 times if normalised against the fine fraction (silt plus clay) content in sediment. Two samples from Mexico City exceed the ERM (Effect Range Median) guidelines and are likely to cause adverse effects. Samples contain only lower chlorinated PCBs (mainly 2-, 3- and 4-CB), thus suggesting that the most used PCB commercial mixture was Aroclor 1242. The homologue composition of the sample taken close to the nuclear power plant of Laguna Verde is identical to this commercial mixture. PAHs in the same samples have relatively low concentrations (14.9–287 ng g−1), well below ERL (Effect Range Low) guidelines. The composition of PAH mixtures accounts for the influence of both petrogenic and pyrolitic sources, with these latter prevailing at some places in Mexico City.  相似文献   

18.
《Organic Geochemistry》1999,30(8):937-945
The anaerobic degradation of the polycyclic aromatic hydrocarbons (PAHs) naphthalene and phenanthrene was investigated in several marine harbor sediments. In sediments from Boston Harbor that were heavily contaminated with petroleum, [14C]-naphthalene and [14C]-phenanthrene were oxidized to 14CO2 without a lag, suggesting that the microbial community was adapted for anaerobic PAH oxidation in situ. The addition of molybdate, a specific inhibitor of sulfate-reducing microorganisms, inhibited PAH mineralization which suggested that sulfate reducers were involved in the anaerobic oxidation of the PAHs. PAHs were also anaerobically oxidized at another site in Boston Harbor that was less heavily contaminated, but at a slower rate than in the most heavily contaminated sediments. Sediments not contaminated with petroleum did not significantly oxidize the PAHs. A similar correspondence between rates of anaerobic PAH oxidation and the degree of PAH contamination was observed in sediments from Tampa Bay and San Diego Bay. When relatively pristine sediments from San Diego Bay that did not have a significant capacity for anaerobic PAH oxidation were exposed to high concentrations of naphthalene, they developed a potential for naphthalene degradation that was comparable to that in sediments that had a history of PAH contamination. The increase in potential for naphthalene degradation in the sediments exposed to naphthalene was associated with an increase in naphthalene-degrading microorganisms. These results suggest that many marine harbor sediments contain microorganisms capable of anaerobically oxidizing PAHs under sulfate-reducing conditions and that these microorganisms will respond with an increase in their activity when PAHs are introduced into the sediments. Thus, if PAH inputs into harbor sediments from petroleum can be reduced there may be a widespread potential for microorganisms to remove this PAH contamination from the sediments, despite anaerobic conditions.  相似文献   

19.
Concentrations and sources of polycyclic aromatic hydrocarbons (PAHs) were investigated in surface sediments of the Yellow River Estuary (YRE). The isobath-parallel tidal and residual currents play important roles in the variation of PAH distribution, such that the contamination level of PAHs in fine-grained sediments is significantly higher than in the relatively coarse grain size sediments. Both diagnostic ratios and principal component analysis (PCA) with multivariate linear regression (MLR) were used to apportion sources of PAHs. The results revealed that pyrogenic sources are important sources of PAHs. Further analysis indicated that the contributions of coal combustion, traffic-related pollution and mixed sources (spills of oil products and vegetation combustion) were 35, 29 and 36 %, respectively, using PCA/MLR. Pyrogenic sources (coal combustion and traffic-related pollution) contribute 64 % of anthropogenic PAHs in sediments, which indicates that energy consumption could be a predominant factor in PAH pollution of YRE. Acenaphthylene and acenaphthene are the two main species of PAHs with more ecotoxicological concern in YRE.  相似文献   

20.
Concentrations of polycyclic aromatic hydrocarbons (PAHs) were measured in a dated sediment core from a reservoir at Osaka City, Southwest Japan. The sediment core consisted of deposits collected over a period of almost 70 years whose PAH content would serve as a historical record of atmospheric environment at Osaka City. Total PAH concentrations varied from 4.2 to 26 mg kg−1 dry wt, and peaked in the 1940s, reflecting the occurrence of a large fire due to air attacks during World War II. The results indicated that warfare had the largest impact on atmospheric environment in Osaka City. Total PAH concentrations decreased in the post-war period except for a small peak. In the 1950s, there was a downward trend from the 1970s to the present. These trends can be ascribed to the growth of industrial activities and the regulation of atmospheric pollutant emissions, respectively.  相似文献   

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