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1.
The aim of this study was to determine the sources and contamination characteristics of polycyclic aromatic hydrocarbons (PAHs) in various environmental media in a karst underground river system. For this purpose, air, underground river water, sediment, and soil samples were collected from a typical underground river in southern China in the dry and wet seasons of 2013–2014, and the compositional spectra, distribution, and ratio characteristics of 16 PAHs were determined for comparative analysis. The results show that three 2–3-ring PAHs (naphthalene, phenanthrene, and fluoranthene) mainly occur in air and underground river water. In sediments and soils, 4–6-ring PAHs are the main components. The PAH concentrations in the air in the wet season are clearly greater than those in the dry season, while it is the opposite in the underground water. Seasonal differences in the concentration of PAHs in the sediments and soils are minor. The concentrations of PAHs in the environmental media overall showed variation in the following order: upstream < midstream < downstream, and this is related to pollutant discharge, adsorption, etc. The main source of PAHs in the upstream area is the combustion of grass, wood, and coal, while it is petroleum in the midstream area, and combustion of grass, wood, coal, and petroleum near the outlet of the underground river. It is necessary to change the energy structure in the study area, improve the efficiency of environmental protection facilities, reduce the emission in vehicle exhaust, and control pollution by PAHs at their sources.  相似文献   

2.
《Applied Geochemistry》1998,13(5):581-591
Six sediment cores were taken in sedimentation zones of the Volga river (located in the southern part of the Russian Federation) and, additionally, 6 sediment cores were taken in several lakes (sedimentation zones) in the central and western part of the Danube delta in Romania. Priority pollutants (8 metals, 7 polychlorinated biphenyls and 10 polycyclic aromatic hydrocarbons) were determined in all samples of all cores. Present-day and historical levels of pollutants since the late 1930s were established through the use of radionuclide time tracers (137Cs, 134Cs). For the persistent metals and polycyclic aromatic hydrocarbons, trends in the concentration profiles during the last 5 decades are described. Low and hardly changing concentrations of As, Cu, Zn and all studied PAHs were observed during the last five decades in the sediments of the Volga river. Recently deposited sediments show slightly increasing levels for the heavy metals Zn and Cr and As in the Volga delta. For the studied metals and PAHs, maximum concentrations were found around 1987 in the sediments of the Danube delta. Sediments deposited around 1940 and recently deposited sediments in the Danube delta showed lower pollutant levels. If the contents of heavy metals, PAHs and PCBs in the aquatic sediments in the deltas of the rivers Rhine, Danube and Volga are compared, it is clear that the Volga delta is and was the cleanest delta during the last 5 decades. Nowadays the contents of heavy metals (except Cu and Ni), PAHs and PCBs in the aquatic sediments of the river Rhine are still highest compared to the other two rivers. The recent load of heavy metals (except Cd and Zn) in the sediments of the river Danube is the highest compared to the other two rivers.  相似文献   

3.
Concentration of aliphatic, aromatic, and chlorinated hydrocarbons were determined from 33 surface-sediment samples taken from the Tidal Basin, Washington Ship Channel, and the Anacostia and Potomac rivers in Washington, D.C. In conjunction with these samples, selected storm sewers and outfalls also were sampled to help elucidate general sources of contamination to the area. All of the sediments contained detectable concentrations of aliphatic and aromatic hydrocarbons, DDT (total dichlorodiphenyltrichloroethane), DDE (dichlorodiphenyldichloroethene), DDD (dichlorodiphenyldichloroethane), PCBs (total polychlorinated biphenyls) and total chlordanes (oxy-, α-, and γ-chlordane and cis + trans-nonachlor). Sediment concentrations of most contaminants were highest in the Anacostia River just downstream of the Washington Navy Yard, except for total chlordane, which appeared to have upstream sources in addition to storm and combined sewer runoff. This area has the highest number of storm and combined sewer outfalls in the river. Potomac River stations had lower concentrations than other stations. Total hydrocarbons (THC), normalized to the fine-grain fraction (clay + silt, < 63 μm), ranged from 120 μg g?1 to, 1,900 μg g?1 fine-grain sediment. The hydrocarbons were dominated by the unresolved complex mixture (UCM), with total polycyclic aromatic hydrocarbons (PAHs) concentrations ranging from 4 μg g?1 to 33 μg g?1 fine-grain sediment. Alkyl-substituted compounds (e.g., C1 to C4 methyl groups) of naphthalene, fluorene, phenanthrere + anthracene, and chrysene series dominated the polycyclic aromatic hydrocarbons (PAHs). Polycyclic aromatic hydrocarbons, saturated hydrocarbons, and the unresolved complex mixture (UCM) distributions reflect mixtures of combustion products (i.e., pyrogenic sources) and direct discharges of petroleum products. Total PCB concentrations ranged from 0.075 μg g?1 to 2.6 μg g?1 fine-grain sediment, with highest concentrations in the Anacostia River. Four to six C1-substituted biphenyls were the most-prevalent PCBs. Variability in the PCB distribution was observed in different sampling areas, reflecting, differing proportion of Arochlor inputs and degradation. The concentration of all contaminants was generally higher in sediments closer to known sewer outfalls, with concentrations of total hydrocarbon, PAHs, and PCBs as high as 6,900 μg g?1, 620 μg g?1, and 20 μg g?1 fine-grain sediment, respectively. Highest PCB concentrations were found in two outfalls that drain into the Tidal Basin. Concentrations of organic contaminants from sewers draining to the Washington Ship Channel and Anacostia River had higher concentrations than sediments of the mid-channel or river. Sources of PCBs appear to be related to specific outfalls, while hydrocarbon inputs, especially PAHs, are diffuse, and may be related to street runoff. Whereas most point-source contaninant inputs have been regulated, the importance of nonpoint source inputs must be assessed for their potential addition of contaminants to aquatic ecosystems. This study indicates that in large urban areas, nonpoint sources deliver substantial amounts of contaminants to ecosystems through storm and combined sewer systems, and control of these inputs must be addressed.  相似文献   

4.
The Xiangjiang River (XR), located in Hunan province in south-central China, is the second largest tributary of the Yangtze River. The occurrence, and sources of the polycyclic aromatic hydrocarbons (PAHs) in the 20 surface sediment samples from XR were analyzed, and the biological risks of the PAHs on the benthic organisms were assessed using sediment quality guidelines. The results showed that the occurrence level of the 16 USEPA priority PAHs in the surface sediments ranged from 190 to 983 ng/g (dry weight) with a mean concentration of 452 ± 215 ng/g. The concentration of phenanthrene was the highest with a mean concentration of 104 ± 44 ng/g. The compositions and principal components analysis indicated that the PAHs in the sediments in XR were mainly from pyrogenic sources which could be attributed to the open burning of rice straws and coal combustion of the local industries in the XR basin. The PAH contamination in the sediments was considered to be moderate, and has posed a small adverse biological effect on the benthic organisms.  相似文献   

5.
To determine the degree of hydrocarbon contamination and the contribution of local petroleum industries to contaminant loadings in sediments from the Beiluohe River, China, 12 surface sediment samples were collected for geochemical analysis in 2005. Sediment samples were extracted by organic solvents, separated by silica gel column chromatography and the profiles of n-alkanes, biomarkers and polycyclic aromatic hydrocarbons (PAHs) in sediments were analyzed by gas chromatography with flame ionization detector and gas chromatography/mass spectroscopy. Concentrations of total hydrocarbons in the sediments varied from 12.1 to 3,761.5 μg g−1 dry wt, indicating that most sediments in Beiluohe River was only slightly to moderately contaminated by hydrocarbons. Concentrations of PAHs for six samples (sum of 16 isomers) varied from 17.7 to 407.7 ng g−1 dry wt and at present low levels of PAHs did not cause adverse biological effects in Beiluohe River sedimentary environment. PAH compositions, n-alkanes and biomarker profiles all suggested that there were different sources of contaminations in studied areas. n-Alkanes reflect two distinct sources: a fossil n-alkane series from crude oil at sites S40, S43, S87 and plantwax n-alkanes at sites S39 and S45. Judged by their PAH ratios, the sediments at site S15 were pyrolytic, sediments at S17 and S43 were petrogenic, and sediments at S39, S40 and S64 had a mixture source of pyrolytic and petrogenic.  相似文献   

6.
Sources of the sixteen polycyclic aromatic hydrocarbons (PAHs) in the United States Environmental Protection Agency priority pollutants list were determined in sediments of Kolo Creek using diagnostic ratios of parent PAHs[phenanthrene/phenanthrene + anthracene; fluoranthene/fluoranthene + pyrene; benz(a) anthracene/benz(a) anthracene + chrysene and indeno(1,2,3-d)pyrene/indeno(1,2,3-cd)pyrene + benzo(ghi)pyrelene]. The study was conducted over four seasons (dry, late dry, rainy and late rainy seasons). Applying cross plots of the diagnostic ratios revealed that PAHs in Kolo Creek sediment have pyrogenic origins except in the rainy season that had petrogenic origins. Comparison of diagnostic ratio values obtained from this study with literature values enabled the further classification into types of pyrogenic and/or petrogenic sources. While the pyrogenic sources of PAHs were mainly as a result of Grass/Wood combustion, the petrogenic PAHs were as result of drained diesel and lubricating oil. The predicted sources corresponded with the prevailing human activities in the vicinity, especially samples collected near a petrol station and an abattoir. This study further affirms the simplicity and accuracy of the use of diagnostic ratios for PAHs source prediction.  相似文献   

7.
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   

8.
孔祥胜  苗迎 《地球学报》2014,35(2):239-247
为证实大气干湿沉降物是岩溶地下河中多环芳烃(PAHs)的来源,研究选择了某城市典型的岩溶地下河水源地作为研究地点,采用大气干湿采样器、聚氨酯泡沫(PUF)大气被动采样器分别采集大气及其干湿沉降物样品,同时采集地下河水样和分层采集流域土壤,利用气相色谱-质谱联用仪(GC-MS)测定了16种PAHs优先控制污染物。结果表明,地下河流域大气干湿沉降中PAHs的干湿沉降通量为147.26 ng·(m2·d)-1,流域PAHs沉降量为1943.8 g;大气中的PAHs浓度为45.33 ng·m-3;地下河水中PAHs浓度平均值为220.98 ng·L-1;土壤中PAHs浓度为38.72 ng·g-1;大气、降雨和土壤中PAHs组成以2~3环的萘、芴、菲、荧蒽、芘5种为主,地下河水中以芴、菲、荧蒽、芘、苯并[a]蒽、苯并[a]芘6种为主。利用地下河多介质中的16种PAHs成分谱、特征比值结合它们的物理化学性质进行PAHs的源解析,研究显示大气干湿沉降是岩溶地下河水中多环芳烃的主要污染源之一,这归因于岩溶地区防污性能的脆弱性。  相似文献   

9.
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   

10.
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   

11.
. Heavy metal concentrations in sediments of the Calabar River: Pb (0.6–30 ppm); Ni (1.2–22.5 ppm); Cr (0.6–3.3 ppm); Cu (0.3–48 ppm); Zn (0.8–27 ppm); Fe (0.2–2,880 ppm) and V (0 ppm) are generally below levels that are known to be harmful to aquatic biota. Metal levels displayed marked seasonal, spatial and tidal variations, which are attributed to both anthropogenic influences and natural processes in the environment. Iron and Cr increased during the dry season (January), while Cu, Zn, Pb and Ni had their peak values in the wet season (September). High values of metals during the wet season indicate inputs through human activities mediated by rainfall. Relatively higher concentrations of metals are obtained during high tide compared to low tide regime. This is attributed to redox processes in the sediment and subsequent displacement of sediment pore water rich in metals by seawater intrusion during high tide. Higher values of Fe observed in the dry compared to the wet season may be attributed to oxidation and precipitation of soluble forms brought into the river during the wet season.  相似文献   

12.
The biodegradability of polycyclic aromatic hydrocarbons such as naphthalene, fluorene, anthracene and phenanthrene by a halotolerant bacterial consortium isolated from marine environment was investigated. The polycyclic aromatic hydrocarbons degrading bacterial consortium was enriched from mixture saline water samples collected from Chennai (Port of Chennai, salt pan), India. The consortium potently degraded polycyclic aromatic hydrocarbons (> 95%) at 30g/L of sodium chloride concentration in 4 days. The consortium was able to degrade 39 to 45% of different polycyclic hydrocarbons at 60 g/L NaCl concentration. Due to increase in salinity, the percent degradation decreased. To enhance polycyclic aromatic hydrocarbons degradation, yeast extract was added as an additional substrate at 60g/L NaCl concentration. After the addition of yeast extract, the consortium degraded > 74 % of polycyclic aromatic hydrocarbons at 60 g/L NaCl concentration in 4 days. The consortium was also able to degrade PAHs at different concentrations (5, 10, 20, 50 and 100 ppm) with 30 g/L of NaCl concentration. The polycyclic aromatic hydrocarbons degrading halotolerant bacterial consortium consists of three bacterial strains, namely Ochrobactrum sp., Enterobacter cloacae and Stenotrophomonas maltophilia.  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.
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   

15.
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   

16.
Toxic organic compounds in wastewater are serious threats for both human and environment healthy states. This study investigates the potential sources of surface water, sediment and groundwater pollution by polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyl (PCBs) as discharged by wastewater into the River of Oued El bey in northeastern Tunisia. Analysis indicates that the concentration of PAHs and PCBs are high in wastewater and vary from 0.37 to 0.83 mg/L and from 0.28 and 1.18 mg/L, respectively. The spatial distribution of PAHs and PCB in surface water showed a variation between 0.37 to 9.91 mg/L and between 0.1 to 0.47 mg/L, respectively. However, the quality of surface water is changed after wastewater evacuation at Oued Tahouna. The determination of PAH and PCB pollutants in groundwater shows a great interest in the development of water resources. The Concentration of these pollutants varying from 0.0204 to 1.93 mg/L and from 0.0052 to 0.196 mg/L, respectively. For PAH, analysis reveals also that naphtelene, fluorene, anthracene and chrysene are the most detected PAHs compounds in water and sediment samples while benzo[b]fluoranthene and benzo[a]pyrene are less present and in trace level. Higher concentrations of PAHs and PCBs are found in samples taken close to industrial areas of Bouargoub and Soliman, and wastewater discharge locations in Soliman. Analysis of the spatial distribution of PAHs and PCBs clearly link their higher concentration in water and sediments to wastewater and manufacturing discharges in the study area. In surface sediment, the organic pollutants are present. The cluster analysis for organic pollutants in different state and different matrix highlight a relationship between the wastewater evacuation and the water qualities which confirmed the direct response of the pollution sources on the surface water and groundwater organic pollution quality.  相似文献   

17.
The Tunisian environmental legislation that follows the EC Directives requires monitoring of persistent, toxic and bio-accumulated substances commonly considered as hazardous substances. In order to comply with this requirement, samples of sea water, sediment and biota from the urbanized and industrialized coast line of Sfax city are investigated. This study presents the results of petroleum hydrocarbon content, distribution and probable origin (anthropogenic and/or biogenic) in 16 intertidal sediments of Sfax coastal area. Alkane distribution indices and hydrocarbon distribution patterns are used to identify natural and anthropogenic input. Non-aromatic hydrocarbons present a high concentration with a range varying from 180 to 1,400 μg/g of dry sediment. The total concentrations of polycyclic aromatic hydrocarbons (PAHs) varied from 0.41 to 5.6 μg/g dry weight. These concentrations are comparable to other marine areas that receive important inputs. n-Alkanes with carbon number ranging from 15 to 35 are identified to be derived from both biogenic and anthropogenic sources in varying proportions. Pristane/phytane ratio shows values lower than 1.4 suggesting the presence of petroleum contamination. This is confirmed by the presence of a large group of unresolved complex mixture and the identification of hopanes with predominant C29 and C30 compounds and steranes with predominance of C27 over C28 and C29 compounds. Ratios of selected PAH concentrations indicate petrogenic and pyrolytic origin of hydrocarbons. Anthropogenic hydrocarbon inputs were more apparent at sites associated with industrial discharges, shipping activities and sewage outfalls.  相似文献   

18.
《Applied Geochemistry》2000,15(7):901-915
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.  相似文献   

19.
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.  相似文献   

20.
Sediments are considered as suitable matrices to study the contamination levels of aquatic environment since they represent a sink for multiple contaminant sources. In this study, the influence of sediment characteristics on the distribution of polycyclic aromatic hydrocarbons (PAHs) and its potential risk in euryhaline, freshwater and humic aquatic bodies of Douglas/Stubbs creek, Ikpa River and Eniong River, respectively, were investigated. The level of PAHs in sediment was quantified using GC–MS, while sediment properties including total organic carbon (TOC) content and grain size were determined by the wet oxidation and hydrometer methods, respectively. The results revealed that the total levels of PAHs in sediment varied significantly between the euryhaline, freshwater and humic freshwater ecosystems. In Ikpa River freshwater ecosystem, a total PAHs load of 1055.2 ng/g was recorded with the suites concentration ranging from 13.0 ng/g (for acenaphthylene) to 161 ng/g (for pyrene). The humic ecosystem of Eniong River had a total PAH load of 11.06 ng/g, while the suites level recorded ranged from 0.04 ng/g for acenaphthene to 2.65 ng/g for chrysene. The total level of PAHs detected in the euryhaline Douglas/Stubbs creek was 14.47 ng/g, and suite concentrations varied between 4.27 ng/g for naphthalene and 5.13 ng/g for acenaphthylene. This shows variation in quantity and quality of PAH contaminants with the nature of ecosystems. It implies complex and diverse contamination sources as well as different capabilities to recover from PAH contamination. Correlation analysis has shown that sediment particle and TOC content influenced PAHs burden in bottom sediments, but the effects varied with the molecular weight of PAHs and the nature of the ecosystems. The TOC was the most significant determinant of PAHs load and distribution in sediment of the freshwater Ikpa River and euryhaline Douglas/Stubbs but had little or no influence in the humic sediment of Eniong River, while the influence of particle size was generally indefinite but slightly associated with PAHs accumulation in the euryhaline sediment. Generally, the total PAH levels (11.0–1055.2 ng/g) recorded were low and below the allowable limit for aquatic sediments. The ecological risk assessment revealed that these levels were lower than the effects range low and effects range medium values. This indicates no acute adverse biological effect although the accumulation of PAHs in freshwater ecosystem of Ikpa River may pose ecological risks as most of the carcinogenic PAH suites had relatively high pollution indices compared to other ecosystem types studied.  相似文献   

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