The Amoco Cadiz oil spill. Distribution and evolution of hydrocarbon concentrations in seawater and marine sediments

The shipwreck of the Amoco Cadiz supertanker on the rocks of the Brittany Coast of France (March, 1978) was one of the most disastrous oil spills ever recorded. The crude oils discharged in the marine environment were light petroleums. The distribution and the evolution of the oil pollution in the marine environment was examined. Chemical studies were limited to an overall estimate of the oil content to assess the importance and the extent of the pollution at the surface, in the water column, and in the sediment. UV fluorescence spectroscopy was used to detect oil in the seawater samples and IR spectrophotometry was used to analyze the sediment samples. Hydrocarbon concentrations in seawater ranged from 0.5 μ/1 to more than 100 μg/1. The oil spill has affected a very large section of the western English Channel. The diffusion of the hydrocarbons into the water column was observed. The evolution of the seawater pollution was followed, and the half-life of hydrocarbons in subsurface water was found to be between 11 and 28 days in different areas. One month after the disaster, the marine sediments were contaminated in the areas reached by the drifting slicks. The highest accumulation of petroleum in the sediments was located in the sheltered coastal environments. The natural decontamination process was found to be related to the nature of the sediment and the energy level of the geographic zone.     

Minimizing the ecological impacts of oil spills

Oil spill response, whether planned by government agencies, oil spill cooperatives or individual companies, can be planned and carried out with the goal of minimizing ecological impacts, not merely removing visible oil. Two oil spill cooperatives on the west coast are implementing such planning. First, a coastal survey was conducted in the cooperative's area of responsibility. Physical processes and habitat types were examined. Oil spill cleanup guidelines were written for each habitat type. Biologically sensitive areas, those sites most vulnerable to oil spill impacts, were identified. Strategies were developed to protect most sensitive areas, i.e., prevent spilled oil from reaching them. Protection is the preferred option because it prevents both the impact of the oil and subsequent cleanup activities. Protected areas can often serve as repopulation centers for surrounding sites that may have been impacted. If minimizing ecological impact is to be a prime focus of oil spill response, ecologists should be involved in both the planning before and the field efforts during such spill events.     

Distribution and hydrodynamic model of the Keumdong oil spill in Kwangyang Bay, Korea

Oil concentrations in the seawater, seabed sediments, and shoreline sediments were measured from the samples collected 165 days after the Keumdong oil spill accident, which had occurred in Kwangyang Bay of the South Sea, Korea in September 1993. Distribution patterns of the concentrations in the seabed and shoreline sediments have allowed us to hindcast the transport and fate of the spilled oil. Overall, the patterns agree better with the southward (seaward) surface water circulation than with the northward (landward) bottom water circulation over the region. Rapid, initial dispersal of the spilled oil to the south and its subsequent grounding onto the intertidal seabed sediments, as well as onto the shorelines, appear to have made ineffective the subsurface oil transport by the bottom current.     

Distribution and hydrodynamic model of the Keumdong oil spill in Kwangyang Bay, Korea

Oil concentrations in the seawater, seabed sediments, and shoreline sediments were measured from the samples collected 165 days after the Keumdong oil spill accident, which had occurred in Kwangyang Bay of the South Sea, Korea in September 1993. Distribution patterns of the concentrations in the seabed and shoreline sediments have allowed us to hindcast the transport and fate of the spilled oil. Overall, the patterns agree better with the southward (seaward) surface water circulation than with the northward (landward) bottom water circulation over the region. Rapid, initial dispersal of the spilled oil to the south and its subsequent grounding onto the intertidal seabed sediments, as well as onto the shorelines, appear to have made ineffective the subsurface oil transport by the bottom current.     

Degradation of polycyclic aromatic hydrocarbons by a bacterial consortium enriched from mangrove sediments

The biodegradability of a polycyclic aromatic hydrocarbons (PAHs) mixture consisted of fluorene (Fl), phenanthrene (Phe) and pyrene (Pyr) by a bacterial consortium enriched from mangrove sediments under sediment-free and sediment slurry conditions was investigated. The enriched consortium made up of three bacterial strains, namely Rhodococcus sp., Acinetobacter sp. and Pseudomonas sp., had a good PAH degradation capability with 100% degradation of Fl and Phe in sediment-free liquid medium after 4 weeks of growth. The Fl and Phe degradation percentages in sediment slurry were higher than that in liquid medium. Autochthonous microorganisms in sediments also possessed satisfactory PAH degradation capability and all three PAHs were almost completely degraded after 4 weeks of growth. Bioaugumentation (inoculation of the enriched consortium to sediments) showed a positive effect on PAH biodegradation after 1 week of growth. Complete biodegradation of pyrene took longer time than that for Fl and Phe, indicating the enriched bacterial consortium had preference to utilize low-molecular weight PAHs.     

Bioremediation of PAHs and VOCs: Advances in clay mineral–microbial interaction

Bioremediation is an effective strategy for cleaning up organic contaminants, such as polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs). Advanced bioremediation implies that biotic agents are more efficient in degrading the contaminants completely. Bioremediation by microbial degradation is often employed and to make this process efficient, natural and cost-effective materials can serve as supportive matrices. Clay/modified clay minerals are effective adsorbents of PAHs/VOCs, and readily available substrate and habitat for microorganisms in the natural soil and sediment. However, the mechanism underpinning clay-mediated biodegradation of organic compounds is often unclear, and this requires critical investigation. This review describes the role of clay/modified clay minerals in hydrocarbon bioremediation through interaction with microbial agents in specific scenarios. The vision is on a faster, more efficient and cost-effective bioremediation technique using clay-based products. This review also proposes future research directions in the field of clay modulated microbial degradation of hydrocarbons.     

Ecological effects of experimental oil spills in Eastern coastal plain estuaries

Ecological effects of weathered and unweathered Louisiana crude oil spilled in eastern coastal plain estuaries were evaluated at all trophic levels and the major chemical components of the oil were followed through selected components of the ecosystem for 36 months.The study site consisted of a natural estuarine marshcreek habitat off the York River, Virginia, modified by the construction of retaining walls to form aquatic and marsh areas in each experimental unit. Each system was closed on all sides with the exception of an opening below the level of lowest tide to allow communication with tidal flow. Five experimental units were constructed, each having a surface area of about 810 m², containing 695 m² of marsh, 100 m² of open water and 15 m² of intertidal mud flat. The most upstream unit served as the control and the four downstream units received dosages of fresh and weathered crude oil. In addition, biological sampling in the open marsh and creek areas was conducted to provide an estimate of the effects of containing the marsh.Five hundred and seventy liters of fresh South Louisiana crude were added to each of the two downstream experimental enclosures approximately three hours into flood tide and were completed in 1 h. The weathered oil was similarly applied to the upstream units 3 days later.The weathered oil was not visible one week after the spill except as coatings on marsh grass blades, while the fresh crude remained for over three weeks. Plankton populations recovered within a week, and fish mortalities, which were most pronounced in the weathered oil unit, ceased after 10 days.Reductions in standing crops of marsh grasses were most pronounced the year following the spills, when peak biomass in the control exceeded the spill units by a factor of three. Recovery progressed further in the second year with peak biomass in the oiled units being about 70% of the control. The third year following the spill, recovery was nearly complete.Benthic populations were dominated numerically by oligochaetes. Significant reductions in populations of this dominant organisms and in populations of polychaetes and amphipods were demonstrable for a period of three years although most of the populations have shown definite signs of recovery.     

Evaporation of phenols from synthetic liquid fuel spills

The environmental impact of a synthetic-fuel spill on a waterway will be determined in part by the rate of dissolution of toxic components into the underlying water and by the rate of removal of those components from the oil by evaporation. In this study, the two film mass transfer model of volatilization was applied to the study of the evaporation of phenols from two synthetic liquid fuels. The rates of evaporation of phenol and alkylated phenols were measured under laboratory conditions. Liquid and gaseous mass transfer coefficients were measured experimentally, and used to calculate Henry's Law coefficients for various phenol-oil pairs from the observed evaporation rates. It was concluded that evaporation rates of phenols from synthetic oils would be significantly less than rates of dissolution in most spills.     

海三棱藨草对崇明东滩沉积物磷素分布的影响

以海三棱藨草为例,运用实验模拟的方法,通过根际、近根和远根沉积物的对比分析,运用根际微生物作用理论,研究了大型植物对潮滩沉积物磷分布及迁移转化的影响。实验结果表明,海三棱藨草通过根系对磷的吸收和自身有机质降解,在沉积物里形成了水平的和垂直的浓度梯度,干扰了磷的正常累积和迁移。通过吸收,海三棱藨草对崇明东滩沉积物中磷的净化速率为16.7~46.1 mg·cm-2·d-1。     

Microbial degradation of hydrocarbons in Ismailia canal water

The biodegradation of hydrocarbons was performed in refinery wastewater obtained by natural microbial flora in Ismailia canal water. About 87% of hydrocarbons were degraded after 9 days under simulated natural conditions. It was found that the addition of fuel oil to the canal water, which already contained significant amounts of refinery wastewater, retarded biological degradation. Percentage of degradation was found to be 67%. This increase in the hydrocarbons concentration affects dramatically on the generation rate of microorganisms present naturally in canal water.     

Biodegradability of hydrocarbons in the refinery wastewater from moustorod oil refinery

The present investigation deals with the study of hydrocarbon degradation present in refinery wastewater by natural microbial flora in addition to that obtained using Ps. aeruginosa under laboratory conditions. Results indicated that Ps. aeruginosa may have a significant role in the degradation of hydrocarbons. After seven days, several of the compounds in the original wastewater were completely degraded and four compounds (n-paraffins) were partially degraded. Without Ps. aerruginosa, the same picture had been obtained after 23 days.     

The use of molecular techniques to characterize the microbial communities in contaminated soil and water

Traditionally, the identification and characterization of microbial communities in contaminated soil and water has previously been limited to those microorganisms that are culturable. The application of molecular techniques to study microbial populations at contaminated sites without the need for culturing has led to the discovery of unique and previously unrecognized microorganisms as well as complex microbial diversity in contaminated soil and water which shows an exciting opportunity for bioremediation strategies. Nucleic acid extraction from contaminated sites and their subsequent amplification by polymerase chain reaction (PCR) has proved extremely useful in assessing the changes in microbial community structure by several microbial community profiling techniques. This review examines the current application of molecular techniques for the characterization of microbial communities in contaminated soil and water. Techniques that identify and quantify microbial population and catabolic genes involved in biodegradation are examined. In addition, methods that directly link microbial phylogeny to its ecological function at contaminated sites as well as high throughput methods for complex microbial community studies are discussed.     

Bioremediation of crude oil pollution in the Kuwaiti desert: The role of adherent microorganisms

Pieces of stones and other solid materials found in the oil lake sites of the Kuwaiti desert appeared clean, providing indications of surface-associated enhanced crude oil degradation. Scanning electron microscope studies revealed that such surfaces were colonized by active microbial populations. The colonization of the stone surfaces was concentrated within crevices. When enriched from washed pieces of stones from the oil lake, the resulting mixed population of adherent microorganisms degraded much more crude oil (44.4%) in the presence of inert carrier materials (styrofoam chips) in laboratory cultures, than in the absence of the inert materials (21.8%). The inert materials were found to be extensively colonized by microorganisms just as was observed with the stone and other solid samples from the oil lake.     

Heavy metal contamination of brown seaweed and sediments from the UK coastline between the Wear river and the Tees river

The concentration of Fe, Mn, Zn, Cu, Pb, Ni, Cr, Cd, and Ag were determined in the brown alga Fucus vesiculosus and intertidal surface sediments from coastal locations of northeast England. Levels of heavy metals similar to those of polluted areas of the British coastline were detected. There is evidence of contamination (especially with Zn and Pb) in sediments from sites affected by colliery spoil and from the Wear estuary. The pelitic fraction ( < 63 microm) is usually more enriched in heavy metals, but it represents a very small percentage of the bulk samples. The fine-grained sand is a very important repository of contaminants especially where particles of colliery spoil, secondary mineral, and amorphous phases are present. Aqua regia-extracted Zn, Cu, and Pb in sediments are significantly correlated with those in seaweed. Despite the closure of all base metal and coal mines, and the cessation of many industrial activities in the region, sediments and brown algae are contaminated with heavy metals. The control site (Holy Island) and the Tees estuary appear to be the least affected.     

Effect of sewage on biodegradability of hydrocarbons in refinery wastewater

The effect of the microbial flora of municipal sewage, with special reference to faecal coliform and faecal streptococci groups, on the hydrocarbons biodegradation of the refinery wastewater from the Moustorod Oil Refinery has been studied. The results indicate that sewage with its microbial flora seems to have a significant role in the biodegradation of hydrocarbons in refinery wastewater. In addition, the early degradation in the wastewater seeded by sewage reveals that faecal streptococci, in addition to other microbial flora, have a significant role in the biodegradation of hydrocarbons.     

Distribution of PCB congeners in aquatic ecosystems: A case study

Polychlorinated biphenyls (PCB) congeners were determined in water samples, sediments, and animal species in the frame of a survey of the River Arrone (Central Italy, near Rome) after a major contamination episode. Animal species were selected on the basis of their living and feeding habits and evaluated as candidate bioindicators of PCB pollution in this lotic ecosystem. Total PCB concentrations in water were found to be low (ng/L level), and in sediments, ranged from about 10 to 200 μg/kg dry weight, depending on the distance from the contamination source. PCB patterns in sediments showed a prevalence of higher chlorinated congeners over time. Concentrations in macroinvertebrates (Calopteryx splendens and Anax imperator) ranged from 60 to 400 μg/kg dry weight, showing significantly different species to species patterns. PCB concentrations were almost parallel in sediments for different sampling stations, while differences in patterns among species can be explained in terms of bioaccumulation/excretion mechanisms. Freshwater shrimps (Palaemonetes antennarius) were not found close to the contamination source, as a consequence of their extreme sensitivity to chemicals, and showed a peculiar pattern (almost exclusively determined by congeners 153, 138, and 180) probably originating from biodegradation mechanisms. Fish samples (Rutilus erythrophthalmus) showed the highest concentrations, as a combination of feeding habit, lipid content, and, probably, less effective biodegradation/excretion pathways. Congener patterns closely match those of Aroclor 1260, which originates from the contamination source. This study confirms that congener physical and chemical parameters, different degradation rates, feeding habits, and mobility of the analysed aquatic organisms, metabolism, and excretion mechanisms, are to be considered to explain the distinctive PCB patterns of different samples.     

Bioremediation of oil sludge-contaminated soil

Bioremediation has become an important method for the restoration of oil-polluted environments by the use of indigenous or selected microbial flora. Several factors such as aeration, use of inorganic nutrients or fertilizers and the type of microbial species play a major role in the remediation of oil-contaminated sites. Experiments were undertaken for bioremediation of oil sludge-contaminated soil in the presence of a bacterial consortium, inorganic nutrients, compost and a bulking agent (wheat bran). Experiments were conducted in glass troughs for the 90-day period. Bulked soil showed more rapid degradation of oil compared to all other amendments. During the experimental period, wheat bran-amended soil showed 76% hydrocarbon removal compared to 66% in the case of inorganic nutrients-amended soil. A corresponding increase in the number of bacterial populations was also noticed. Addition of the bacterial consortium in different amendments significantly enhanced the removal of oil from the petroleum sludge from different treatment units.     

Concentrations of Cu and Pb in the offshore and intertidal sediments of the west coast of Peninsular Malaysia

Malaysia is now a developing country and on her way towards being an industrialised one by the year 2020. Most of her industries and urban areas are located on the west coast of Peninsular Malaysia. In addition, the offshore area of the west coast is now one of the busiest shipping lanes in the world. These two phenomena make the intertidal and offshore areas of the west coast of Peninsular Malaysia interesting for scientific studies. Therefore, this study focused on both the offshore and intertidal sediments of the west coast of Peninsular Malaysia. Sampling for sediment samples were done from the northern to the southern ends of the peninsula and these sediment samples were analysed for Cu and Pb. It was found that total Cu concentrations ranged from 0.25 to 13.8 and 0.40 to 315 microg/g dry weight (dw) for offshore and intertidal sediments, respectively. For Pb, it ranged from 3.59 to 25.4 and 0.96 to 69.8 microg/g dw for the offshore and intertidal sediments, respectively. The ranges of Cu and Pb found from the west coast of Peninsular Malaysia were low in comparison to regional data. However, some intertidal areas were identified as receiving anthropogenic Cu and Pb. Geochemical studies revealed that the 'nonresistant' fraction for Pb contributed about 70.0% to 75.0% and 54.0% of the total Pb concentration in the offshore and intertidal sediments, respectively. As for Cu, the 'nonresistant' fraction contributed about 46.2% to 60.4% and 46.3% of the total Cu concentration in the offshore and intertidal sediments, respectively. The 'nonresistant' fraction contained mostly of anthropogenic metals besides natural origins. These 'nonresistant' percentages indicated that both the offshore and intertidal areas could have received anthropogenic-derived metals, which could be influenced by physico-chemical properties of the sediments. Although the present data indicated that contamination due to Cu and Pb in the west coast of Peninsular Malaysia especially in the offshore areas were not serious, regular biomonitoring studies along the west coast of Peninsular Malaysia are recommended.     

Naphthalene biodegradation kinetics in an aerobic slurry-phase bioreactor

The research was focused on the slurry-phase biodegradation of naphthalene in soil. Among ex situ techniques, the slurry phase offers the advantage of increased availability of contaminants to bacteria. From naphthalene contaminated soil, a Pseudomonas putida M8 strain capable to degrade naphthalene was selected. Experiments were performed in a stirred and oxygenated reactor. In this study, the influence of air flow rate and agitation rate on volatilisation and biodegradation of naphthalene was investigated. The hydrocarbon disappearance, the carbon dioxide production, and the ratio of total heterotrophic and naphthalene-degrading bacteria was monitored. The results obtained confirm that the selected bioremediation technology is successful in the treatment of contaminated soils.