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1.
《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   

2.
Sediment denitrification is a microbial process that converts dissolved inorganic nitrogen in sediment porewaters to N2 gas, which is subsequently lost to the atmosphere. In coastal waters, it represents a potentially important loss pathway for fixed nitrogen which might otherwise be available to primary producers. Currently, data are lacking to adequately assess the role of denitrification in reducing or remediating the effects of large anthropogenic nitrogen loads to the coastal zone. This study describes the results of 88 individual measurements of denitrification (as a direct flux of N2 gas) in sediment cores taken over a 3-yr period (1991–1994) from six stations in Boston Harbor, nine stations in Massachusetts Bay, and two stations in Cape Cod Bay. The dataset is unique in its extensive spatial and temporal coverage and includes the first direct measurements of denitrification for North Atlantic shelf sediments. Results showed that rates of denitrification were significantly higher in Boston Harbor (mean=54, range<5–206 μmol N2 m?2 h?1) than in Massachusetts Bay (mean=23, range<5–64 μmol N2 m?2 h?1). Highest rates occurred in areas with organic-rich sediments in the harbor, with slower rates observed for low-organic sandy sediments in the harbor and at shallow shelf stations in the bay. Lowest rates were found at the deepest shelf stations, located in Stellwagen Basin in Massachusetts Bay. Observed rates were correlated with temperature, sediment carbon content, and benthic macrofaunal activity. Seasonally, highest denitrification rates occurred in the summer in Boston Harbor and in the spring and fall in Massachusetts Bay, coincident with peak phytoplankton blooms in the overlying water column. Despite the fact that sediment denitrification rates were high relative to rates reported for other East Coast estuaries, denitrification losses accounted for only 8% of the annual total nitrogen load to Boston Harbor, a consequence perhaps, of the short water-residence times (2–10 d) of the harbor.  相似文献   

3.
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   

4.
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5.
《Organic Geochemistry》1999,30(8):891-900
The fate of polycyclic aromatic hydrocarbon (PAH) mixtures in marine sediments can be difficult to determine due to extraction, analytical and matrix barriers. The purpose of this work was to develop and validate methods to kill indigenous microorganisms in marine sediments, to spike the sediments with a mixture of PAHs in a minimally invasive fashion and to age the treated sediments while following the effects of the treatments on the PAHs and several groups of microorganisms. Following gamma irradiation (0.0, 2.5, 3.5 and 5.0 Mrad), the sediments were mixed with known amounts of PAHs that had been coated onto fine-grained sand. During the subsequent ageing process, levels of extractable PAHs and numbers of microorganisms were monitored. The addition of PAHs to the unirradiated sediment seemed to rapidly induce the degradation of phenanthrene, fluoranthene and pyrene, while these PAHs decreased to a much smaller extent in the irradiated sediments in the 376 days of the experiment. The heavier PAHs, chrysene and benzo(a)pyrene, showed slight decreases in extractable concentrations at all irradiation levels, suggesting PAH sequestration/ageing over time. While some microbial populations recovered rapidly, culturable PAH degraders did not recover at any irradiation level tested and concentrations of light molecular weight PAHs in sediments irradiated at all levels dropped only slightly. This suggests that even the lowest dose (2.5 Mrad) may inhibit PAH degradation sufficiently to permit ageing of the spiked sediments for 6 months to a year. The methods described show promise for the generation of realistic, well-characterized spiked sediments for use in biodegradation and bioavailability experiments.  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.
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   

8.
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   

9.
In a 3-yr study, late prespawning winter flounder were collected from various stations in Long Island Sound (three of them heavily urbanized) and spawned in the laboratory. For comparative purposes, flounder from two sites in the Boston Harbor area were similarly treated in 1987 and 1988. Of the stations in Long Island Sound, New Haven Harbor alone consistently produced low percent viable hatch and small larvae. Boston Harbor produced the smallest larvae of all sites. There were no significant station-to-station differences in lipid utilization during larval development; yolk reserves at stations showing a low percent viable hatch, small larvae, and low embryonic development rate were probably used in part for stress metabolism. No significant differences in concentrations of polychlorinated biphenyls for collections from Long Island Sound were found either in livers of spawned fish, in sediments, or in eggs of winter flounder. The very low metal concentrations in winter flounder eggs showed no relation to the degree of metal contamination found at stations in Long Island Sound and Boston Harbor.  相似文献   

10.
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   

11.
 Shallow, anaerobic groundwater near a former manufactured-gas plant (MGP) in Charleston, South Carolina, USA, contains mono- and polycyclic aromatic hydrocarbons (MAHs and PAHs, respectively). Between 1994 and 1997, a combination of field, laboratory, and numerical-flow and transport-model investigations were made to assess natural attenuation processes affecting MAH and PAH distributions. This assessment included determination of adsorption coefficients (K ad ) and first-order biodegradation rate constants (K bio ) using aquifer material from the MGP site and adjacent properties. Naphthalene adsorption (K ad =1.35×10–7 m3/mg) to aquifer sediments was higher than toluene adsorption (K ad =9.34×10–10 m3/mg), suggesting preferential toluene transport relative to naphthalene. However, toluene and benzene distributions measured in January 1994 were smaller than the naphthalene distribution. This scenario can be explained, in part, by the differences between biodegradation rates of the compounds. Aerobic first-order rate constants of 14C-toluene, 14C-benzene, and 14C-naphthalene degradation were similar (–0.84, –0.03, and 0.88 day–1, respectively), but anaerobic rate constants were higher for toluene and benzene (–0.002 and –0.00014 day–1, respectively) than for naphthalene (–0.000046 day–1). Both areal and cross-sectional numerical simulations were used to test the hypothesis suggested by these rate differences that MAH compounds will be contained relative to PAHs. Predictive simulations indicated that the distributions of toluene and benzene reach steady-state conditions before groundwater flow lines discharge to an adjacent surface-water body, but do discharge low concentrations of naphthalene. Numerical predictions were "audited" by measuring concentrations of naphthalene, toluene, and benzene at the site in early 1997. Measured naphthalene and toluene concentrations were substantially reduced and the areal extent of contamination smaller than was both observed in January 1994 and predicted for 1997. Measured 1997 benzene concentrations and distribution were shown to be relatively unchanged from those measured in 1994, and similar to predictions for 1997. Received: 26 June 1997 · Accepted: 25 August 1997  相似文献   

12.
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.  相似文献   

13.
As a US east coast state with a major income from outdoor recreation and tourism, Delaware highly values its environmental quality and natural resources. However, no results on polycyclic aromatic hydrocarbons (PAHs) contamination in soil at natural recreational areas (NRAs) in the state have been reported. In this study soil samples from seven state parks, two city parks, two state forests, and two national wildlife refuges in Delaware were analyzed for the concentrations of 12 selected PAHs. Results indicated that the median concentration of total PAHs in urban, suburban, and rural NRAs was 1,159, 138, and 130 μg/kg, respectively. Based on the classification proposed by Maliszewska-Kordybach, soil PAH contamination level at almost all sampling sites in urban NRAs was classified as contaminated or heavily contaminated, while that at sampling sites in suburban and rural NRAs was classified as not or weakly contaminated. Principal component analysis showed that all these areas share the same independent variable, which may be composed of one or more contribution sources. Pyrogenic processes were inferred to be the major source of soil PAH contamination in Delaware NRAs. Individual PAH concentration at all sampling sites were observed below the limit of Canadian Quality Guidelines except for site F3, where the concentration of benzo[b]flouranthene, benzo[k]flouranthene, and benzo[a]pyrene was found to exceed the limit by 88.3, 125, and 281 %, respectively. Further investigation on PAH contamination and possible remediation in area F are recommended.  相似文献   

14.
Surface soil samples were collected from 161 sites throughout the downtown and suburban area of Beijing, China. The samples were analyzed for polycyclic aromatic hydrocarbons (PAHs) concentrations. Through Kriging analysis, five heavily contaminated zones were identified in the study area. Sources of PAHs in the soil were apportioned using principal factor analysis and multiple linear regression. Three factors were identified representing coal combustion/vehicle emission, coking emission, and petroleum sources, respectively. The relative contributions of the three sources were 48% for coal/vehicle emission, 28% for coking emission, and 24% for petroleum sources. The contributions of total PAHs from the three sources were 16.4, 4.63 and 3.70 ng g−1, respectively. Spatial analysis indicated that the contribution of coal/vehicle sources was higher in the downtown area than in the suburban area, the petroleum sources had a high contribution in the urban area, and the contribution of coking sources was high in the suburban area. The results indicated that PAH contamination in the surface soil in Beijing was closely related to the spatial characteristics of energy consumption and functional zoning. Improvement of the energy consumption structure and relocation of industries with heavy pollution are effective ways to control PAH contamination in surface soil in the area.  相似文献   

15.
A combination of methods (infaunal grabs and sediment profile cameras) were used to monitor the response of Boston Harbor benthic habitats to reductions in wastewater associated with movement of the outfalls to the mouth of the harbor and then offshore. From 1992 to 2006, there was strong evidence that benthic habitats within Boston Harbor have shifted from a more anaerobic state to a more aerobic state and that these changes are directly related to changes in carbon loading associated with outfall placement and improvements in wastewater treatment. Over the period of 1992 to 2000, when the ocean outfall started to operate, there was >90% reduction in organic loadings to Boston Harbor from 11,400 to 1,200 t C per year. There were also corresponding decreases in primary production due to reduced nutrient loadings. The most apparent change in harbor benthos was the widespread increase in 1992 and subsequent decline by 2005 in Ampelisca spp. tube mats. The long-term increase in thickness of the apparent color redox potential discontinuity layer was consistent with reductions in organic loading and increases in bioturbation. The optimal organic loading for maintaining large areas of amphipod tube mats and high bioturbation rates was around 500 g C per square meter per year. Above and below this level, the area of tube mats in Boston Harbor declined.  相似文献   

16.
The New York Bight is a sector of the Middle Atlantic continental shelf. The Bight consists of a part of the Atlantic Ocean offshore of the New York and New Jersey metropolitan area. This area includes the most populated coastal setting in North America. The Atlantic shelf and its estuaries are used for waste disposal, dredging, commercial fishing, and recreation; activities that contribute to the contamination of associated bottom sediments. Existing data for toxicants are still inadequate. Improvements in sediment and water quality will require a more detailed knowledge and understanding of sediments and water in the Bight. Eleven coring stations were established in New York Bight. Decreases in pH and Eh both above and below the water/sediment interface are attributed to the activity of anaerobic bacteria. Sulfate reduction is one of the important processes in lowering pH. Low Eh values of up to −443 can be related to sulfate-reducing bacteria. The highest negative Eh generally occurs with the highest organic carbon concentration. Core samples yielded up to 4.00% organic carbon compared to 0.8 to 1.2% in sediments of the natural nearshore environment. Twenty-seven different aliphatic hydrocarbons, fourteen PAHs, five cyclic hydrocarbons, and eight dicarboxylic acids were identified in the Bight pore waters. Sediment located deeper in the Hudson Shelf Valley has a greater abundance of aliphatic hydrocarbons as adsorbed pollution on clay and silt. The presence of dicarboxylic acids leached from plastic came from anthropogenic activities (mostly sewage). PAHs have two sources: coal ash (observed in sediments) and petroleum (part of the sewage, run-offs, and oil spills). The rest of the hydrocarbons have a petroleum or biogenic origin. The high amount of organic carbon may be the result of sewage sludge or originated from natural sources. The main sources of contaminants are dumpsites, emergency releases after heavy rainstorms from sewage-treatment plants, tanker washing, storage transfer spills, run-off, and air-borne pollution. The relatively high accumulation of organic matter causes oxygen depletion, which creates anaerobic conditions. The presence of hydrogen sulfide makes the environment toxic for most of the biota. Detected hydrocarbons, especially PAHs easily enter the food chain and may cause cancer and mutagenic reactions of biota and humans. Organic petrology of six organic-rich sediments from New York Harbor illustrates a diverse population of anthropogenic and natural organic components. Three core samples (V-2, AC-4, and HV-3) contain coarse-textured organic matter. A slim majority of those components are anthropogenic. They are derived mainly from coal combustion by-products. The other two core samples (AC-6 and T-1) contain mainly very fine-grained organic matter. A majority of them are amorphous organic matter (AOM) that is derived from bacterial degradation of modern organic matter. Radionuclide dating (137Cs, K-40, Pb-210) shows post-1950 components for the shallowest intervals in the cores (<30 cm). The post-1950 sediment, distributed in the tops of core, is recycled material from the dumpsites. The underlying sediment has isotopic signatures that suggest dates before active dumping.  相似文献   

17.
This paper summarizes evidence that most of the considerable nitrogen loading (～8, 470 mmol total N m?2 yr?1) to Boston Harbor (Massachusetts, USA) is expelled to shallow shelf waters of Massachusetts Bay, where it strongly influences ecological dynamics. Examination of nitrogen concentrations in the harbor, compared with loading, indicated that removal processes are active in the harbor. Comparison to other estuarine systems showed that the harbor’s nitrogen concentrations are consistent with its loading, if they are corrected for tidal flushing effects on the water residence time. Furthermore, extensive measurements of sediment denitrification confirmed that rates of N2 gas loss are high in an absolute sense (～600–800 mmol N m?2 yr?1) but nonetheless remove only a small portion (<10%) of the annual land-derived nitrogen loading. Burial in sediments apparently removes only about 2% of the N input, implying export to offshore environments as the major removal process (～88–90% of N input). Western Massachusetts Bay receiving waters were examined for a signature of export from the harbor. Data consistently show a gradient of decreasing nitrogen concentrations from the harbor to about 10–20 km into the bay. In many cases, plots of nitrogen concentrations versus salinity show nearly conservative mixing character, which implies virtual export. Seasonally, the data suggest most of the export from the harbor in winter is as dissolved inorganic forms (NH4 +, NO3 ?, NO2 ?). In summer, export is dominated by the outflow of organic nitrogen forms. Chlorophyll export is evident as well, suggesting that the nutritional coupling of the harbor and bay in summer involves organic fertilization of the bay’s surface water. Finally, high-resolution studies over different stages of the tidal cycle help refine understanding of the advection of chlorophyll and stimulation of in situ chlorophyll growth at the seaward edge of the tidal excursion into the bay.  相似文献   

18.
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   

19.
Sediment cores from two locations in Green Bay and two in lake Michigan were analyzed for 12 polycyclic aromatic hydrocarbons (PAHs), loss-on-ignition (LOI),210Pb,137Cs, and7Be to study differences in deposition patterns between the freshwater estuary Green Bay, with several local sources, and the open Lake Michigan, dominated by atmospheric inputs. We found that the remote sites receive relatively less high-molecular weight PAHs such as ideno(1,2,3-cd)pyrene and dibenz(ah)anthracene and are more depleted in anthracene and pyrene. This may be related to a low Henry’s law constant for the high molecular compounds and to selective photo-oxidation of anthracene and pyrene during transport. While sedimentation rates are higher in Green Bay than in the open lake, the PAH levels are generally comparable (0.3–8.5 μg g?1) in the two areas. However, the highest PAH levels are found in a core from Green Bay (GB88G). The two Green Bay cores have total PAH concentration maxima in 1985, which appear to be related to the combustion of petroleum. Also, one Green Bay core (GB88G) and the two from Lake Michigan exhibit PAH maxima in the early 1950s in agreement with observations from other study areas. There is a significant correlation between total PAH and LOI, and thus total organic carbon, for the Green Bay cores, but little or no such correlation for the Lake Michigan cores. This may indicate that PAHs in Green Bay are effectively scavenged by settling detritus.  相似文献   

20.
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   

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