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1.
We investigated changes of prokaryotic diversity during bioremediation experiments carried out on anoxic marine sediments characterized by high hydrocarbon and metal content. Microcosms containing contaminated sediments were amended with lactose and acetate and incubated in anaerobic conditions up to 60 d at 20 or 35 °C. Microcosms displaying higher degradation efficiency of hydrocarbons were characterized by the dominance of Alphaproteobacteria and Methanosarcinales and the lack of gene sequences belonging to known hydrocarbonoclastic bacteria. Multivariate analyses support the hypothesis that Alphaproteobacteria are important for hydrocarbon degradation and highlight a potential synergistic effect of archaea and bacteria in changes of metal partitioning. Overall, these results point out that the identification of changes in the prokaryotic diversity during bioremediation of contaminated marine sediments is not only important for the improvement of bio-treatment performance towards hydrocarbons, but also for a better comprehension of changes occurring in metal partitioning which affect their mobility and toxicity.  相似文献   

2.
The bacterial communities in the anoxic layer of a heavily polluted microbial mat and their growth on hydrocarbons under sulfate-reducing conditions were investigated. Microbial communities were dominated by members of Alphaproteobacteria (27% of the total rRNA), Planctomycetes (21.1%) and sulfate-reducing bacteria (SRB: 17.5%). 16S rRNA cloning revealed sequences beloning to the same bacterial groups with SRB affiliated to the genera Desulfobulbus, Desulfocapsa, Desulfomicrobium, Desulfobacterium and Desulfosarcina/Desulfococcus. The derived enrichment cultures on crude oil, hexadecane and toluene were dominated by SRB. While most SRB sequences of the toluene and hexadecane cultures were related to the sequence of Desulfotignum toluolica, the crude oil enrichment showed a more diverse bacterial community with sequences from the genera Desulfotignum, Desulfobacter, Desulfatibacillus, Desulfosalina, and Desulfococcus. We conclude that the anoxic layer of the studied mats contains a diverse community of anaerobic bacteria, dominated by SRB, some of which are able to grow on hydrocarbons.  相似文献   

3.
The level of hydrocarbons present in the sediments of real estate canals on the east and west coast of Florida was determined using gas chromatography. Although the amount of alkanes present was found to be comparatively low, the ratio of the amount of odd carbon-numbered alkanes to even carbon-numbered alkanes suggested that canals on the Gulf of Mexico are receiving an influx of petroleum products. In addition, the most probable number technique was used to enumerate total aerobic heterotrophic bacteria, aerobic hydrocarbon-degrading bacteria, sulfate reducing bacteria, and sulfate-reducing hydrocarbon-degrading bacteria present in the canal sediments. Results showed significantly higher numbers of hydrocarbon degrading bacteria in the sediments of the west coast canals.  相似文献   

4.
We sampled nekton, benthic infauna, and sediments in salt marshes of upper Galveston Bay, Texas to examine relationships between habitat use and sediment hydrocarbon concentration. Most marsh sediment samples were contaminated with relatively low concentrations of weathered petroleum hydrocarbons. We found few statistically significant negative relationships between animal density and hydrocarbon concentration (6 of 63 taxa examined using simple linear regression). Hydrocarbon concentration did not contribute significantly to Stepwise Multiple Regression models we used to explore potential relationships between animal densities and environmental parameters; in most cases where hydrocarbon concentration was an important variable in the models, the relationship was positive (i.e., animal densities increased with hydrocarbon concentration). Low hydrocarbon concentrations in sediments of upper Galveston Bay marshes could have contributed to our results either because levels were too low to be toxic or levels were toxic but too low to be detected by most organisms.  相似文献   

5.
Two types of river sediments with contrasting characteristics (anoxic or oxic) were resuspended and the release of heavy metals and changes in water chemistry were investigated. During resuspension of the anoxic sediment, the dissolved oxygen (DO) concentration and redox potential of the water layer decreased abruptly within the first 1 min, followed by increases toward the end of the resuspension period. Heavy metals were released rapidly in the first 6 h, probably due to the oxidation of acid volatile sulfide (AVS) of the anoxic sediment, and then the aqueous phase concentrations of the heavy metals decreased due to resorption onto the sediment until the 12‐h point. During resuspension of the oxic sediment, the DO concentration and redox potential remained relatively constant in the oxic ranges. The heavy metals were released from the oxic sediment gradually during a 24‐h resuspension period. The temporal maximum concentrations of Ni, Cu, Zn, and Cd in the aqueous phases in both experiments frequently exceeded the USEPA water quality criteria or the water quality guidelines of Australia and New Zealand. This suggests that a resuspension event could bring about temporal water quality deterioration in the two sediment environments.  相似文献   

6.
This investigation showed that urban stormwater runoff provides a significant amount of petrogenic material to receiving waters and sediments. A characteristic hydrocarbon ‘fingerprint’ for sediments and particulate matter in the Hillsborough Reservoir, Hillsborough River and upper Hillsborough Bay was provided. Determination of source material for petroleum contamination in stormwater runoff and river sediment indicated that crankcase oil was a primary contributor to sediment hydrocarbon contamination. A comparison of sediment hydrocarbons with hydrocarbons from stormwater runoff showed that the most probable source of crankcase oil-like petrochemicals found in sediment was the stormwater runoff.A comparison of hydrocarbon composition in suspended particulate matter with that of accumulated bottom sediments in the reservoir, river and bay, during a non-storm period and rising tide showed no resuspension and upriver transport of petroleum contaminated bay sediment. No special influence of the bay upon the lower river was observed relative to hydrocarbon tracers, indicating that most contaminated sediment transport was downriver during storm events. Additional studies should be performed over various tidal cycles and storm events incorporating sediment cores, sediment grain size analysis and hydrocarbon characterization at more closely spaced stations near the river mouth to address adequately the question of specific hydrocarbon pollution sources, rate of petroleum influx and persistence of petrochemical contaminants in the sediment.  相似文献   

7.
The effects of urban development cause substantial physical changes in coastal waterways through hardening and reclamation of river banks, alteration of water flow, and diffuse and point-source discharges of pollutants. The cumulative effects of urbanization on the fauna of estuaries are not well understood. This study examined the benthic infauna of two urban and three rural estuaries near Townsville, North Queensland. A range of univariate and multivariate statistics was used to relate variation in the benthic assemblages to concentrations of contaminants (heavy metals and hydrocarbons) within the sediments of each estuary. Sediments in the most developed estuary contained concentrations of heavy metals and petroleum hydrocarbons that were several orders of magnitude greater than those from non-urban waterways. The fauna at these sites was dominated by cirratulid and sternaspid polychaetes and lacked filter-feeding bivalves and other molluscs that were common in less developed estuaries. These differences were generally consistent throughout each estuary, indicating estuary-wide patterns of change, that were most strongly associated with spatial patterns in the distribution of Pb, Cu and hydrocarbons.  相似文献   

8.
As part of a study on microbial redox alteration of humic substances we investigated the potential effect of this metabolism on the fate of heavy metals and hydrocarbons as a result of conformational alteration of the humic molecular structure due to microbial reduction. Our studies indicate that the microbial reduction of humic acids (HA) results in significant morphological and geochemical alterations. X‐ray microscopy analysis indicate that the conformational structure of the humic colloids is altered as a result of the redox change. In the reduced state, the HA appeared as small dense particles, on reoxidation, large loose aggregates were formed. In addition, spectrofluorometric studies indicated that the binding capacity of the HA for naphthalene was decreased by 10% when the HA was reduced. Similarly, the reduced HA yielded higher surface tension values at all concentrations tested which is indicative of a more hydrophilic and less hydrophobic solute. On reoxidation, the surface tension values reverted back to values similar to those obtained for the untreated oxidized HA. These data indicate that the hydrophobicity of the HA is altered on biological reduction of the HA and that this alteration is reversible. In contrast the reduced HA demonstrated a 15% higher affinity for heavy metals such as divalent cobalt than the oxidized HA. In addition to increasing the binding capacity of HA for heavy metals, the reduction of the HA also decreased the bioavailability and toxicity of bound heavy metals such as chromium. When incubated in the presence of Cr(III) and HA, cells of Escherichia coli grew much more rapidly in the presence of the reduced HA suggesting that the higher metal binding capacity of the reduced humic substances resulted in a removal of the Cr(III) from solution and hence reduced its bioavailability and toxicity. These studies demonstrate that HA redox state and reduction of humic acids by microorganisms can have a significant effect on the molecular morphology and binding constants of HA for heavy metals and hydrocarbons and also directly affects the bioavailability of these compounds in the environment.  相似文献   

9.
湖泊疏浚堆场淤泥污染及潜在生态风险评价   总被引：1，自引：0，他引：1  
疏浚淤泥内通常含有不同类型的有毒有害物质,在堆场直接堆放过程中可能会对周围环境产生有害影响.本文针对太湖及巢湖相应疏浚堆场内淤泥进行研究,探讨淤泥中重金属、多环芳烃以及多氯联苯等污染物含量及潜在生态风险;根据重金属的风险指数法和持久性有机污染物的风险商法,对各污染物的潜在生态风险进行定量分析.研究结果表明,太湖白旄堆场以及孔湾堆场淤泥内重金属及多环芳烃含量较小,潜在生态风险较低;巢湖南庄堆场淤泥内各类有害物质含量较大,种类较多,对于周围环境具有较高的潜在生态威胁.多氯联苯则在各个疏浚堆场淤泥中具有很高的积累量,潜在生态风险较高,应引起管理者的重视.  相似文献   

10.
Metallic contaminants associated with sediments showed various behaviours depending on physicochemical conditions. A contaminated sediment core from a harbour in the Bay of Seine was sampled to derive information about metal solubilization from anoxic sediment. In these anaerobic surroundings, physicochemical processes depended on the organic matter cycle, on vertical variation of redox conditions and on precipitation conditions of iron and manganese. In the studied core, anoxic conditions were developed at -15 cm depth. A three-step sequential extraction procedure, modified from the BCR method (now the SM&T), was applied to the anoxic sediment in order to evaluate the potential mobility of fixed metals. Zinc was the most labile metal, recovered in the first extraction stages, and was associated with the non-residual fraction of sediment. Lead was the least labile metal, with up to 70% associated with the residual fraction of the sediment. Copper was associated with organic matter, and its mobility was controlled by the concentration and degradation of the organic fraction. Discharge of organic-rich dredged sediments at sea results in degradation of contained organic matter and may affect the environmental impact of these metals significantly. These results therefore help to improve the waste management of such contaminated sediments.  相似文献   

11.
《Marine pollution bulletin》2017,114(1):192-200
To achieve a better contaminant removal efficiency in a low-temperature and high-salt environment, two novel strains of cold- and salt-tolerant ammonia-oxidizing bacteria (AOB), i.e., Ochrobactrum sp. (HXN-1) and Aquamicrobium sp. (HXN-2), were isolated from the surface sediment of Liaohe Estuarine Wetland (LEW), China. The optimization of initial ammonia nitrogen concentration, pH, carbon–nitrogen ratio, and petroleum hydrocarbons (PHCs) to improve the ammonia-oxidation capacity of the two bacterial strains was studied. Both bacterial strains showed a high ammonia nitrogen removal rate of over 80% under a high salinity of 10‰. Even at a temperature as low as 15 °C, HXN-1 and HXN-2 could achieve an ammonia nitrogen removal rate of 53% and 62%, respectively. The cold- and salt-tolerant AOB in this study demonstrated a high potential for ammonia nitrogen removal from LEW.  相似文献   

12.
A survey of hydrocarbons and the sterol coprostanol, together with a hydrocarbon degradation experiment, was conducted in a coastal marine environment in East Antarctica. Aliphatic hydrocarbon levels in sea-ice algae were 1.9–12.5 mg m−2 and in seawater particulate matter 0.07–0.17 μg l−1. Sea-ice algae contained the diatom biomarker, the highly branched isoprenoid (ip) diene ipC25:2, and Southern Ocean seawater particulate matter samples were distinguished from near shore samples by the presence of nC21:6. Sea-ice algae and seawater particulate matter samples showed a predominance of even chain n-alkanes. Hydrocarbon levels in sediment samples from anoxic fjord basins were high (45–48 μg g−1) compared to a sub-tidal marine sample (0.7 μg g−1), and were predominantly of bacterial origin. Contaminants detected were linear alkyl benzenes in sewage effluent from Davis station, and polycyclic aromatic hydrocarbons (PAH) which were present in very low levels (parts per trillion) throughout the environment. High levels of 2,6-dimethylnaphthalene were found in anoxic sediment from Ellis Fjord and may arise from a novel bacterial source. Coprostanol concentrations in sediments ranged from 67 to 1280 ng g−1. A dual origin is proposed from marine mammalian faeces and, at several sites, from conversion of algal-derived sterols by anaerobic bacteria. Future studies examining the impact of human sewage from scientific bases or other ventures should use care in interpreting results when such high baseline values, from marine mammalian input, may occur naturally around the Antarctic coast. The potential exists, however, for the technique to distinguish between human and mammalian inputs through measurement of the coprostanol to epicoprostanol ratio, particularly if undertaken with appropriate comparative sampling. Results for a hydrocarbon degradation experiment where a light fuel was applied to an Antarctic beach, showed loss of up to 99% of the fuel within 2 months, mainly by volatilization.  相似文献   

13.
The chemical effects of chronic petroleum input into a shallow water marsh were examined by measuring hydrocarbon levels and dissolved organic carbon content of sediments associated with two active oil fields in south Louisiana. Annual levels of total organic carbon in the surface waters of the oil fields were higher by 1 mg C/l. in the salt marsh and 5 mg C/l. in the fresh marsh than the respective controlsites. Average dissolved organic carbon concentrations in the interstitial waters of cores taken within the oil field environments were 105% higher than the control in the salt marsh and 43% higher than the control in the fresh marsh. Significantly lower ratios of C17 to pristane occurred in both oil field sediments; however, average odd-even predominance values were not indicative of petroleum contaminated sediments. The results indicate that microbial processes are responsible for dissolution of petroleum into dissolved organic carbon and that dissolved organic carbon concentrations may be a more significant measure of chronic petroleum input than hydrocarbon distribution.  相似文献   

14.
A radiotracer method that measures rates of oxidation of methane to carbon dioxide has been applied to anoxic marine sediments. The results confirm the occurrence of anaerobic methane oxidation and agree with model predictions of a zone of intense anaerobic methane oxidation at the base of the sulfate-reducing zone.  相似文献   

15.
The distribution of oil hydrocarbons in bottom sediments of Onega Lake was examined. Their qualitative and quantitative composition was examined by methods of IR-spectroscopy and chromatography-mass spectrometry. The background concentrations of oil hydrocarbons in bottom sediments are evaluated and the polluted area is determined. The major regularities in oil hydrocarbon transformations under natural conditions and anthropogenic impact are identified. The quantitative development of the bacterial groups that take part in the transformation of complex organic substances and oil product derivatives in the case of emergency pollution of Petrozavodsk Bay water area by oil products is demonstrated.  相似文献   

16.
A study of surface sediment organic matter and heavy metal content (e.g. Cu, Zn, Pb and Sn) was carried out in 2006 to assess changes in eutrophication and pollution in the periodically anoxic Flensburg Fjord since 1972. Low hydrodynamic activity together with sewage discharges and high primary production in the inner fjord promote the enrichment of present day surface sediments in organic matter and metals in contrast to the outer fjord. However, heavy metal contents in the fjord are typical for the western Baltic Sea, although they are higher than in the preindustrial period.Although the anthropogenic nutrient load has substantially decreased since the 1970s, sediments from the inner fjord contain more organic material in 2006 than in 1972 resulting from still high levels of primary production supported by internal nutrient loading. Of the heavy metals measured, a decrease in Pb content since the 1970s is distinct, which is explained by the banning on gasoline lead. Taken together, these results suggest that the amelioration of environmental conditions needs time but is indeed related to reduced anthropogenic inputs.  相似文献   

17.
The composition and distribution of aliphatic (n-alkanes) and polyaromatic hydrocarbons (PAHs) were measured for the surface sediments collected at 25 sites from Jiaozhou Bay, Qingdao, China. Total n-alkanes and PAH concentrations ranged from 0.5 to 8.2 microg/gdw and 0.02 to 2.2 microg/gdw, respectively, and the distribution of both n-alkanes and PAHs showed large spatial variations in the bay. The distribution of PAHs in the sediments was predominated by the three or more ring compounds. High hydrocarbon levels were generally found in the areas associated with high anthropogenic impact and port activities in the bay. The calculated hydrocarbon indexes suggest that petroleum contamination was the main source of n-alkanes, while both pyrolytic and petrogenic sources contributed PAHs to the surface sediments of Jiaozhou Bay. In comparison to other polluted coastal sediments, the level of contamination from both aliphatic hydrocarbons and PAHs in Jiaozhou Bay sediments is relatively low at the present time.  相似文献   

18.
The deterioration of sediments is a serious environmental problem. Controlling nutrient release fluxes from sediments is important to alleviating eutrophication and to reducing terrigenous nutrient loads. The purpose of this study was to evaluate the phosphate removal performance of granulated coal ash (GCA) from seawater, which is produced from coal thermal electric power generation. Batch experiments were carried out to investigate the removal kinetics of phosphate from seawater under both oxic and anoxic conditions. Phosphate was removed well from seawater under both oxic and anoxic conditions. The adsorption isotherm for phosphate revealed that GCA could remove phosphate effectively from seawater above a concentration of 1.7 μmol L−1. GCA can reduce the concentration of phosphate in seawater effectively under anoxic conditions where iron type adsorbents cannot be applied. Therefore, GCA could potentially be used to adsorb phosphate in the organically-enriched sediment, which generally occurs under highly reductive conditions.  相似文献   

19.
In this study, mineral magnetic properties and petroleum hydrocarbons were statistically analysed in four sediment cores (C1, A1, T1 and K1) from the north east coast of Tamilnadu, India to examine the feasibility of PHC concentrations assessment using magnetic susceptibility. The C1 and A1 cores reveal a clear horizon of increase in PHC above 35 and 50 cm respectively suggesting the excess anthropogenic loading occurred in the recent past. Magnetic properties which were enhanced in the upper part of the sediment cores were the result of ferrimagnetic minerals from anthropogenic sources. Factor analysis confirmed that the input of magnetic minerals and petroleum hydrocarbons in Chennai coastal sediments are derived from the same sources. The present study shows that instead of expensive and destructive PHC chemical methods, magnetic susceptibility is found to be a suitable, cheap and rapid method for detailed study of petroleum hydrocarbon contamination in marine sediments.  相似文献   

20.
The article gives the results of studying the concentration and composition of aliphatic and polycyclic aromatic hydrocarbons in suspension in surface waters at sections from the English Channel and Skagerak Strait to various regions of the Baltic Sea (2010–2015) and in water and bottom sediments of the southeastern part of the sea in the water area of the Kravtsovskoe field (2008–2015). In recent years, the surface waters of open areas of the Baltic Sea showed a decrease in hydrocarbon concentrations down to background levels (12–33 μg/L). The maximal concentration of hydrocarbons (in excess of the MAC) was recorded in different seasons in navigation areas, including the English Channel and Pregola R. mouth. In the zone of the Kravtsovskoe field, the concentration and composition of hydrocarbons in water depends on their inflow from the bank, and the same characteristics in bottom sediments, on the rate of their leakage from sediment stratum. A decline in these processes have led to a decrease in hydrocarbon concentrations in the sediments of a local area near D-6 platform to background levels (5–7 μg/g) and to the predominance of terrigenous, rather than petroleum, alkanes in hydrocarbon compositions.  相似文献   

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