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1.
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   

2.
The concentration of selected contaminant trace metals and organic contaminants, namely polycyclic aromatic hydrocarbons (PAHs), normal-alkanes, total polychlorinated biphenyls (PCBs), and other organochlorines, was studied in cores from shallow-water fine-grain sediments from both sides of the maximum turbidity zone (MTZ) in the upper estuary of the St. Lawrence. Average trace metal concentrations in the cores were generally lower in downstream sediments, except for Hg and Pb. Hg levels in the cores were very high, exceeding 0.7 μg g?1 in core C168 (south shore) and 0.19 μg g?1 in core LE (north shore). Trace metal concentrations in all the cores were highly variable with depth, but after normalization with reference to iron, the trend was remarkably uniform, thus confirming an important inverse relationship with grain size. A similar lack of a well-defined trend was noted in the profiles of the organic components in the modern sediments. Average PAH values for modern sediments at core sites C168 and LO were 1.05 μg g?1 and 0.44 μg g?1, respectively (i.e., less than or equal to those in Lake Ontario and upstream in the river). PCB values far exceeded those in upstream sediments (average: 347 ng g?1 in core LE and 158 ng g?1 in C168), but were less than in Lake Ontario. Concentrations of chlordane, heachlorobenzene, and mirex were relatively low and uniform in the modern sections of the cores. The vertical uniformity of both the contaminant profiles and those for Cs-137 (C168) suggests that the sediments are relatively young (i.e., definitely less than 35 yr at C168, and probably even less at LE and LO). Therefore no long-term or historical trend is evident.  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.
《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   

5.
Burrowing crabs (Chasmagnathus granulata), sediment collected from inside and outside crab burrows as well as outside the crab bed, and cordgrass (Spartina densiflora) were collected from intertidal mudflat and cordgrass marsh habitats and analyzed for concentrations of polychlorinated biphenyl (PCB) congeners and organochlorine (OC) compounds to test the hypothesis that there are differences in the distribution and bioaccumulation of OC contaminants in coastal lagoon habitats in Argentina. PCB concentrations were relatively low, although the penta- and hexachlorobiphenyl detected in sediments and biota indicated that there had been direct inputs of PCBs into the ecosystem. Heptachlor epoxide, dieldrin, endosulfan sulphate, chlordane compounds, DDT and metabolites, and hexachlorocyclohexanes (HCHs) were the major pesticides detected in sediment and biota samples. When lipid-normalized concentration data for all OC pesticides in crabs were summed together (ΣOCC), there were higher concentrations in crabs from the cordgrass habitat in comparison to crabs from the mudflat. In sediment samples, there were no significant differences in percent organic matter of marsh and mudflat sediments, but the concentrations of ΣOCC normalized to organic carbon were higher in the sediments collected in the cordgrass marsh. Samples of rhizomes and roots from the cordgrass contained high concentrations of OC compounds and it was estimated that 2.4 kg of heptachlor epoxide, the most abundant OC pesticide, may be present in the total cordgrass root biomass in Mar Chiquita lagoon. These data indicated that the cordgrass in coastal lagoon environments is an important factor in determining the distribution of persistent contaminants, and that a significant portion of the total burden of these hydrophobic compounds may be deposited in cordgrass biomass.  相似文献   

6.
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.  相似文献   

7.
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.  相似文献   

8.
Geochemical analysis of the bottom sediments of Lakes Banryoko, Onbe, Hamahara and Kijima in Shimane prefecture of southwest Japan was carried out to determine their metal concentrations, and to assess the potential for ecological harm by comparison with sediment quality guidelines. The work conducted includes water quality measurement, and analyses of trace and major elements and rare earth element (REE) of sediments. Results showed that water quality of the lakes contrasts slightly between their upper and lower parts. Average abundances of As, Pb, Zn, Cu, Ni, and Cr in Banryoko sediments were 27, 33, 90, 27, 25, and 46 ppm, respectively, compared to 31, 52, 175, 44, 44, and 75 ppm at Onbe, 11, 26, 96, 13, 13, and 35 ppm at Hamahara, and 24, 43, 193, 31, 12, and 30 ppm at Kijima. These concentrations exceeded the lowest effect level that has moderate impact on aquatic organisms as proposed by the New York State Department of Environmental conservation. Pb and Cu abundances are comparable to the Coastal Ocean Sediment Database threshold, while As and Zn exceed this value, indicating the concentrations of these metals are potentially toxic. Increases in the abundances of these metals in lake sediments are probably related to the reducing condition of the sediments, anthropogenic sources and surface soil erosion. The REE patterns of sediments in the study areas are broadly comparable to the average upper continental crust, but show some contrast between lakes due to differing source litho type. Significant positive correlations between Fe2O3 and As, Pb, Zn, and Cu were found in the sediments, suggesting these metals may be adsorbed on Fe oxides in the lake sediments.  相似文献   

9.
El Bey river, which drains 60% of the pollutant load of several urban cities in the northeast of Tunisia, provides a good example of the transfer of organic and metallic pollutants that result from industrial and urban activity, and can be used to show how these charges are transported and discharged into the Gulf of Tunis. Persistent organic pollutants (PAH and PCB) in dissolved, particulate matter, bed sediments, and three wastewater effluents in El Bey watershed were analyzed. PAH (∑14PAHs) concentration ranged from 0.248 to 9.955 mg L?1 and from 0.836 to 28.539 mg L?1 in dissolved and particulate fraction respectively. The particulate/dissolved partition coefficient value (Kd) was less than one which confirmed the affinity of PAH to be adsorbed. In sediment, the high-molecular weight PAHs were found principally with percentage between 50 and 100% witch present 239.99 to 5362.19 μg kg?1, which is relatively higher in comparison with other estuaries river. Contrary to PAH patterns, PCB were bound to dissolve fraction. Kd (PCB) value (Kd?>?1) reflected this affinity which is related to environment energy. The spatial distribution and profile of analyzed organic pollutants confirmed the direct impact of wastewater effluent on the organic pollution level in three compartment of El Bey watershed and his profiles suggested different transport patterns.  相似文献   

10.
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.  相似文献   

11.
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.  相似文献   

12.
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   

13.
The temporal distributions for six classes of trace organic contaminants (chlordanes, DDTs, dieldrin, PAHs, PCBs, and butyltins) in oysters from six Galveston Bay sites from National Oceanic and Atmospheric Administration’s National Status and Trends (NS&T) Mussel Watch Program are compared with other NS&T sites from the Gulf of Mexico as well as all NS&T sites of the United States (East Coast, West Coast, and Gulf of Mexico). Decreases in the median for the Gulf-wide concentration of chlordanes, dieldrin, and butyltins occurred during 1986–1994. The Gulfwide median concentrations of DDTs, PAHs, and PCBs exhibited a strong cyclic distribution with time. For Galveston Bay oysters, “high” concentration is defined as the concentration greater than the median plus one standard deviation for all Gulf of Mexico sites. The percentage of sites having high concentrations during 1986–1994 for Galveston Bay oysters are 49% for dieldrin, 45% for butyltins, 40% for chlordanes, 38% for PCBs, 30% for PAHs, and 21% for DDTs. For PCBs, 43% of Galveston Bay oyster samples analyzed over the first 9 yr have concentrations high enough for potential biological effects to be observed in oysters. The percentages in other agents were chlordanes (22%), butyltins (22%), dieldrin (5%), and PAHs (4%). National Academy of Science-proposed regulatory limits for oysters were exceeded in only 2% of Galveston Bay samples for DDTs and 1% for PCBs. All other contaminants were below proposed NAS limits.  相似文献   

14.
《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   

15.
《Applied Geochemistry》2005,20(6):1195-1208
The upper intertidal zone, and salt marshes in particular, have been shown by numerous authors to be effective medium to long-term storage areas for a range of contaminants discharged or transported into the estuarine environment. A detailed understanding of the specific controls on the trapping and storage of contaminants, however, is absent for many estuarine systems. This paper examines heavy metal distribution and accumulation in two contrasting Spartina sp.-dominated macrotidal salt marsh systems – a rapidly prograding, relatively young marsh system at the Vasiere Nord, near the mouth of the Seine estuary, France, and a more mature, less extensive marsh system in the Medway estuary, UK. The spatial distribution of the heavy metals Zn, Cu, Pb, Ni and Co is assessed and compared in both systems via detailed surface sampling and analysis, while the longer-term accumulation of these metals and its temporal variability is compared via analysis of dated sediment cores. Of the two sites studied, the more extensive marsh system at the Vasiere Nord in the Seine estuary shows a clear differentiation of heavy metals across the marsh and fronting mudflat, with highest metal concentrations found in surface sediments from the more elevated, interior marsh areas. At Horrid Hill in the Medway estuary, the spatial distribution of heavy metals in surface sediments is more irregular, and there is no clear relationship between heavy metal concentration and site elevation, with average concentrations similar in the marsh and fronting mudflats. Sediment core data indicate that the more recent near-surface sediments at Horrid Hill are clearly more contaminated than those at greater depth, with most heavy metal contamination confined to the upper 20 cm of the sediment column (with peak metal input in the late 1960s/early 1970s). In contrast, due to extremely rapid sediment accretion at the mouth of the Seine, heavy metal distribution with depth at the Vasiere Nord site is relatively erratic, with metal concentrations showing a general increase with depth. These sediments provide little information on temporal trends in heavy metal loading to the Seine estuary. Overall, heavy metal concentrations at both sites are within typical ranges reported for other industrialised estuaries in NW Europe.  相似文献   

16.
The lateral distributions of Mn concentrations in the sediments of two Swiss lakes under varying oxygen conditions have been determined. The comparison of Mn distribution patterns with oxygen in the deep-water provides strong evidence for a geochemical-focusing effect, which is driven by the redox cycle of manganese. Conditions essential for this process to occur are anoxic sediments in contact with oxic deep-water. Average sedimentary manganese concentrations determined for different water-depth ranges are directly proportional to the area of shallower sediments. This result indicates that geochemical-focusing of manganese in lake sediments is a promising proxy indicator for the reconstruction of oxygen conditions during deposition.  相似文献   

17.
《Applied Geochemistry》1997,12(3):327-332
This paper describes an investigation carried out in 1990 by the Geological Survey of Norway into the contamination of soils and groundwater at a former industrial site. The site covers an area of 0.5 ha and was used for a small plant generating gas for lighting purposes and from the middle of the last century for a small electrochemical facility (The Nidelven Brass and Iron Co. Est. 1843). The site is located immediately adjacent to the Nidelva river, in the central area of the city of Trondheim (pop. 150,000), Norway. Soil samples were obtained from 10 boreholes drilled to approximately 4 m depth. Analysis of the heavy metal content of these soil samples was subsequently undertaken. A subset of the samples was analysed for tar, including polycyclic aromatic hydrocarbons (PAH). The concentrations of Cd, Co, Cr, Hg, Ni and PAH in the soils are all below the maximum permissible levels recommended by the authorities. In certain localities, however, the concentrations of Cu, Pb and Zn are higher than the action levels at which remediation is required. It is estimated that approximately 4400 m3 of soil are contaminated, but that the contaminants are bound so tightly to the soil that the risk of dispersion of the pollutants is negligible.Groundwater samples were also collected from 4 monitoring wells installed at the site. Analysis of these groundwaters indicated the presence of only slightly contaminated groundwater. With the exception of 1 sample with a slightly higher concentration of Cu, the concentrations of PAH and the trace metals Co, Cr, Cu, Hg, Ni and Zn in the groundwater were below natural background values. This confirms the results from the soil analyses in which it was concluded that the dispersion of contaminants is negligible. A TCLP-extraction of 5 soil samples with high concentrations of Cu, Pb and Zn showed that only Zn was released in amounts exceeding the water guidance levels requiring monitoring.This study therefore indicates that the contaminants found in the ground at the site are strongly bound to the soil and are unlikely to be mobilised. This, combined with a slow base-flow, causes an insignificant contamination contribution to the waters in the River Nidelv. It should be noted, however, that the leaching experiments were not undertaken on the samples containing the highest Cu, Pb and Zn concentrations.  相似文献   

18.
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   

19.
Stream sediments of two well-weathered and aerated drainage areas of Colorado containing anomalous amounts of silver were allowed to react by shaking with nitric acid of different concentrations (1–10M). Silver, manganese, and iron simultaneously dissolved were determined by atomic absorption. The relationship between silver dissolution and the dissolution of manganese and/or iron was evaluated by linear and multiple regression analyses. The highly significant correlation coefficient (r = 0.913) between silver and manganese dissolution suggests that manganese oxides are the major control on the scavenging of silver in these stream sediments, whereas iron oxides only play a secondary role in this regard.  相似文献   

20.
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.  相似文献   

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