Afield analysis of the effect of oil and gas derived produced water discharges on the vegetation of one freshwater and two brackish wetlands in coastal Louisiana was conducted. Aboveground biomass, plant species composition, pH and salinity were measured to determine if the produced water discharge in each marsh was related to differences in plant response. Of the three marshes investigated, only one of the brackish marshes exhibited significantly lower live aboveground biomass at the site receiving produced waters compared to its adjacent reference site. Although interstitial salinities were significantly higher at the treatment site of this brackish marsh, the salinity difference between treatment and reference sites was only 1·5 ppt in a marsh with a mean salinity of 11·9 ppt. This salinity difference should have no discernible biological effect on the brackish species inhabiting this marsh. Also, the differences in species composition between treatment and reference sites of each marsh did not indicate a produced water effect. Thus, at these three produced water discharge sites the dilution of the produced water in the discharge canals, plus the sinking of higher density produced water to canal bottoms (thus making it less available for tidal movement into the marsh), appears to prevent a biologically significant negative impact on the marsh vegetation. Whether this conclusion is valid for other produced water sites needs further evaluation.
A study of the effects of the water soluble fraction of Iraq crude oil on eggs, larvae and postlarvae of gilthead sea bream, Sparus aurata is presented. The water soluble fraction of Iraq crude oil greatly affects eggs of gilthead sea bream, causing mortality, deformities, narcotic effects and reduced motility. Larvae in all water soluble fraction concentrations died after 72 h. At the start of exposure, growth and yolk sac resorption increase, but after 24 h both decrease compared to the controls. Of the early stages, postlarvae seem to be most resistant to the water soluble fraction of Iraq crude oil.
The Minerals Management Service estimates the likelihood of oil spills of 1000 barrels and greater occurring in association with the production and transportation of offshore oil on the US Outer Continental Shelf (OCS). The estimation process uses a spill rate constant, based on historical accidents, expressed in terms of number of spills per 109 barrels of oil produced or transported. The mean spill occurrence estimate is obtained by multiplying the rate constant by the volume of oil projected to be handled. The probability of one or more spills occurring in a given production period is then estimated by using the mean number of spills in a Poisson process. The calculated occurrence rates of 0·60 spills per 109 barrels produced on US OCS platforms and 0·67 spills per 109 barrels transported in US OCS pipelines represent a decline of 40 and 58%, respectively, since last evaluated in 1983. Spill occurrence rates for worldwide tanker transport remained unchanged, since last evaluated in 1983, at 0·90 for ‘at-sea’ spills and 0·40 for ‘in-port’ spills.
The distribution of oil degrading bacteria (ODB) and its ratios to viable heterotrophic bacteria (CFU) and direct counts (AODC) were examined in relation to the surface currents of the western Caribbean Sea. High ODB/CFU and ODB/AODC ratios were found, suggesting that chronic sources of hydrocarbons in the region may have a larger impact than those in the southern Gulf of Mexico, where previous studies have been performed. It was concluded that, in western Caribbean waters, the distribution of oil degrading bacteria, or its ratios to CFU or AODC, could be useful indicators of chronic oil inputs originating at the east of the Caribbean Sea, as well as their motions afterwards.
A common method of detecting a small leak in a pressurized underground storage tank pipeline system containing petroleum is to monitor the pressure in the line. This paper presents theoretical models to predict the pressure changes associated with leaks and product temperature changes in pressurized pipelines. These models have been validated in experiments at retail petroleum facilities and the EPA's UST Test Apparatus. A heat conduction model is used to estimate the waiting period prior to the beginning of the test that is long enough to allow the product temperature changes to be negligibly small, and an exponential pressure-decay model is used to estimate the test duration that allows the pressure drop associated with small leaks to exceed the threshold. The results suggest that a test duration of 15 to 60 min is required to detect leaks as small as 0·1 gal/h and a waiting period of up to 6 to 12 h is required for the temperature changes in a 2-inch diameter pipeline to be negligible after the last dispensing of product through the line.
Sediment samples were collected to study the dispersion and fate of mineral oil hydrocarbons from the above-water discharge of oiled drill cuttings at two exploration well sites. At the shallow water (16 m), exposed location, the primary method of dispersion was wave action. Aliphatic hydrocarbon samples at times showed substantial weathering and concentrations decreased to ten times background at approximately 200 m from the wellhead. The oiled cuttings pile under the drill rig was observed to disappear within three months.At the deeper water (70 m) location, the dispersal mechanism was ocean (tidal) currents and the oiled cuttings appeared to be much more persistent. Hydrocarbon samples showed no significant weathering and aliphatic concentrations remained more than an order of magnitude above background 1500 m from the wellhead in the primary current direction. Concentrations three orders of magnitude above background were confined within 400 m, and four orders within 200 m. Aromatic hydrocarbon profiles at both well sites indicated a source other than the base oil.
The ability of the marine Alteromonas sp. 17 to degrade hydrocarbon substrates was investigated. This strain effectively degraded various liquid and solid hydrocarbons. Growth on the long chain alkane eicosane was studied. The relationship between degradation efficiency of this solid hydrocarbon (80% degradation) and potential bioemulsifier production by the marine strain was investigated. Production of non-dialyzable bioemulsifier, monitored by decrease of surface tension and emulsifying capacity measurements, was observed. The bioemulsifier was able to emulsify various types of hydrocarbons. Its basic composition was 37 mg litre−1 carbohydrates and 15·58 mg litre−1 lipids. Major lipids were polar lipids (phospholipids, monoglycerides, glycolipids). The strain exhibited moderate adherence to liquid hydrocarbons but was non-adherent to solid hydrocarbon.
A modelling study of transport of vinyl chloride monomer in the sea following a leakage from the sunken ship B. Montanari is presented to help evaluate the impact of several strategies to save the environment from a leakage of the substance and to assess the area affected by concentrations that are considered harmful. As a first step, parameters of a stationary and a nonstationary leakage were estimated. The parameters included the discharge rate, the mean sea current vector, an extinction coefficient and the horizontal dispersion coefficient. The estimation was necessary since the complete behaviour of the substance in real conditions was not known. Upon completion of the estimation procedure, simulation of several cases was attempted. Firstly, results are presented concerning a transient concentration field in an unbounded environment following possible releases. Secondly, the results of the stationary leakage are compared for different current fields in the Bay of Remetic where the ship was taken for unloading.
In an attempt to develop a nonpolluting method for used oil disposal, sharp sand bed filtration and the continuous elution technique were used on a bench scale to carry out the reclamation of used industrial hydraulic oils. Both processes gave quantitative yields of reclaimed oils. Assessment of the qualities of these oils using standard ASTM procedures and IR spectroscopy showed that the reclaimed oils are similar to the base oil from which the hydraulic oil was formulated. The metallic impurities in the used oil were completely removed, and the oils totally dehydrated. The yields from the continuous elution process were generally higher than those of the sharp sand filtration technique.
The impacts of oil and dispersed oil on freshwater ecosystems were examined in afield experiment conducted as part of the Freshwater Oil Spill Research Program. In July 1985, 3 m3 of Normal Wells crude oil were spilled on each of two fen lakes. The slick on one lake was treated with the dispersant Corexit 9550. Corexit 9550 was effective in removing the oil from the water surface even though wave energy was very low. The oil or dispersed oil had little detectable short or long term impact on all water quality parameters measured, or on the microbial populations and activities in the water column and sediments of both lakes. Untreated oil caused more damage than the dispersed oil to floating aquatic plants and the shoreline vegetation, but new growth within the affected areas was observed one month after treatment. Seasonal regrowth of vegetation in all areas affected by the treatments appeared normal. Our results suggest that the best response to oil contamination in isolated fen lakes is no action at all. However, floating oil or oil washed ashore could pose a significant threat to indigenous wildlife or its habitats. Under these conditions, chemical dispersion may prove to be an effective alternative when conventional control and recovery measures are not feasible.
An experimental procedure is described to estimate the extent of evaporative weathering experienced by crude oils spilled in the marine environment. The essence of the procedure is the division of the crude oil into a series of pseudo-fractions by boiling point, and the subsequent modelling of the evaporative behaviour of each with the appropriate n-paraffin. The n-paraffin distributions of a number of naturally weathered crude oils were determined by capillary gas-liquid chromatography using fused silica columns. The actual extents determined by this procedure were compared with those generated by a computer simulation of the weathering, where the evaporative losses were modelled using film thickness, film temperature and weather data. Excellent results were obtained for oil film thicknesses between 10 μm and 1 mm, weathered for periods of up to 4 weeks.
Levels of aliphatic hydrocarbons within the boiling range of alkanes n-C-14 to n-C34 were determined in samples of surface sediments and in two bivalve species, Unio tigridis and Pseudodontopsis euphraticus (Unionidae), from seven locations in the lower reaches of the rivers Tigris and Euphrates, and the upper Shatt Al-Arab. These levels, and data derived from them, indicate only slight pollution, mostly by degraded hydrocarbons arising from anthropogenic sources. The Shatt Al-Arab samples were most contaminated and those from the river Tigris the least contaminated.
A pipeline break on 23 April 1985 near Nairn, Louisiana, resulted in the release of approximately 300 barrels of Louisiana crude oil into a brackish marsh dominated by a vegetative mixture of Spartina patens, S. alterniflora and Distichlis spicata. Since the impact of oil spills on brackish marshes has received little attention, we initiated this investigation to assess the post-spill status of the vegetation. Sixty-eight randomly selected plots located on 15 transects which traverse the complete study area were sampled for various vegetative cover parameters. The major impact of the spill was confined to the 50-acre (20-ha) marsh located immediately around the pipeline rupture. The oil caused a 64% reduction in live vegetative cover (adjusted for differences in total percentage cover among plots) in this marsh 3 months after the spill. This high plant mortality from a relatively low oil dosage (estimated at 0·28 liters/m2) was probably due to the contact of the oil with a large percentage (about 30–70%) of the photosynthetic leaf surfaces of the vegetation and the penetration of the oil into the marsh substrate.
ELSA is a new diagnostic system to support decision-making in respect of accidental spills in the marine environment. This paper describes the newly developed methodology, intended to analyse and to characterize the gravity of an accident, which matches in an adequate way the needsfor simplicity, speed and completeness in the initial stages of an accident. By this approach the gravity of an accident is presented in an overall scale of value which is easy to interpret. The overall gravity is the sum of the subscale value(s) for hazards such as toxicity in air, bioaccumulation, persistence, flammability, explosiveness, toxicity in water, corrosiveness, carcinogenicity or radioactivity. The approach is based on criteria such as practicality, acceptability, accuracy and completeness, and is intended for operational use in the initial stage of an accident. The methodology is therefore implemented on a computer model to describe and quantify, as fast as possible, the gravity of an accident which involves substances that have the potential to produce adverse effects on the marine environment, users of the sea or response personnel. Such a diagnostic system is necessary for appropriate decisions on the cautionary response (the protection of human life and health, and the protection of the natural environment) and the corrective response (recovery and containment or control of the pollution). This model may assist responsible authorities in judging the gravity of an accident at sea and will provide a means whereby the general public and the press will more easily reach a reasonable assessment of the true nature of accidents to which the authorities are responding.
The application of fluorescence spectroscopic techniques to the uptake of aromatic hydrocarbons into the sandprawn, Callianassa kraussi , was examined. Animals were exposed to the water-soluble fraction of Qatar crude oil for up to 12 weeks, then depurated in clean seawater for up to 4 weeks. Fixed wavelength measurements showed the extent and rapidity of aromatic hydrocarbon accumulation into the hepatopancreas of C. kraussi These measurements, along with synchronous spectra, were useful in demonstrating differential accumulation of light and heavy aromatic hydrocarbons.
A vertical selective migration of low and medium molecular weight hydrocarbons is demonstrated in the depth of a tropical forest soil heavily impacted by a crude oil spill. An identical pattern of horizontal migration is observed in the lateral zone of the polluted area and in the sediments of a shallow river which received the contaminated water runoff of the forest. The differential migration, which is attributed to the chromatographic properties of the media, resulted in the formation of a residual contaminant similar in composition to a gas-oil cut. The environmental contamination by this fraction extended far beyond the area initially polluted by the crude oil.
Plaice (Pleuronectes platessa), dab (Limanda limanda) and sole (Solea solea), caught by netting in the vicinity of selected Southern North Sea gas production platforms, were assessed by an expert sensory panel for possible tainting (atypical flavour). Selected samples offish tissue and sediment were analysed for n-alkanes.
The effect of Qatar Light crude oil on the saltmarsh crab Sesarma catenata was investigated. These crabs are well adapted to the estuarine environment and mainly occur in the zone dominated by the saltmarsh grass Spartina maritima. They have an excellent aerial respiration and water-saving system and their burrows do not penetrate to water level. Static bioassays conducted showed that adult crabs are fairly resistant to the water-soluble fraction (WSF) of the crude oil, but that larval survival is affected at a much lower WSF concentration. Many of the crabs were, however, affected during the bioassays and may be considered as ‘ecologically’ dead.
Five lorries shipped on board the ferry “Herald of Free Enterprise” that sank off the Belgian coast in 1987 contained together over a hundred different chemicals. During the intricate salvage operation that followed the tragedy, the environmental protection activities met with technical, scientific, legal and organizational difficulties. An assessment of the exact nature, harmfulness, and situation of the cargo had to be done while access to the casualty was limited, and information insufficient. The risks for the personnel and for the marine environment were evaluated using both simplified scenarios and sophisticated computer simulations. Environmental contamination was monitored and protective counterpollution measures were implemented under supervision of the authorities. Although more than half the dangerous cargo was lost, environmental damage was kept to a minimum.
Potential environmental impacts of materials discharged from oil and gas development and production platforms off the coast of southern California (Santa Maria Basin) are being monitored during an ongoing, long-term (fiveyear) field program. The study combines hypothesis testing of platform effects with basic research on the structure and dynamics of the regional ecosystem over a time series encompassing both seasonal and repeated annual scales. Oceanographic features and processes that are being measured focus on the benthos and include biological community indices and species abundances for hard-bottom and soft-bottom (macroinfauna and meiofauna) assemblages; levels and distributions of trace metals and hydrocarbons in bottom sediments, suspended particulates, animal tissues, and pore waters; water currents and otherphysical-oceanographicfeatures; various sedimentological properties (sediment grain size, total organic carbon, shear strength, distribution of mineral types, radioisotope profiles, and degrees of sediment mixing as a result of bioturbation); sediment and pollutant-transport processes; and animal-sediment-pollutant interactions. Synoptic measurement of these different environmental variables over the extended sampling period provides an opportunity to examine long-term variability in the benthic environment with respect to both natural and anthropogenic causes. Efforts to distinguish between natural variability and low-level cumulative impacts of drilling are given special attention.
