Improved approaches to ecotoxicity testing of petroleum products

Crude oils produced in the North West shelf of Western Australia are highly volatile, a characteristic not shared by most of the Northern Hemisphere crude oils on which internationally accepted toxicity test protocols were developed. Because of this volatility and some other factors, the LC50 and EC50 values obtained from acute toxicity tests will be significantly affected by the changes of toxicant concentration in test solutions during the period of exposure. To address these issues all steps of a standard protocol for crude oil toxicity testing have been revised. A systematic study has been performed on factors which affect petroleum hydrocarbon solubilisation in aqueous systems during test solution preparations. The influence of mixing time, agitation energy and volume/interface ratio on a hydrocarbon concentration in a water-soluble fraction (WSF) was studied for heavy, medium and light crude oils. A study of the sensitivity of marine unicellular algae to WSF of crude oils was conducted with Isochrysis sp., Nannochloropsis-like sp. and Nitzchia closterium. Total concentrations of hydrocarbons dissolved in test solutions were estimated by UV-spectrometry and GC/FID chemical analyses. When the toxicant concentration decreased during the exposure period, the EC50 values derived from initial or final concentrations either underestimate or overestimate toxicity, respectively. Therefore, weighted average concentrations (WAC) calculated for the whole test period were recommended for expressing hydrocarbon concentrations in test solutions of crude oils. Toxicity indices calculated from WAC of total hydrocarbons for different crude oils can be compared regardless of the rates of hydrocarbon loss.     

Monitoring biomarkers in fish (Lepidorhombus boscii and Callionymus lyra) from the northern Iberian shelf after the Prestige oil spill

Hepatic biomarker responses were measured in two demersal fish species (Lepidorhombus boscii and Callionymus lyra) from the northern Iberian shelf associated with the massive Prestige oil spill (POS), five months after the accident. The biomarkers selected were 7-ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST), glutathione reductase (GR), catalase (CAT), and DNA integrity. Interspecies differences and spatial variations in biomarker responses were observed along the shelf. GST, GR and CAT activities were significantly elevated in L. boscii in the most oil impacted area (Finisterre) and positively correlated (p<0.05) with POS tar aggregate densities. The lack of previous data from the area together with the existence of chronic background pollution of the shelf implies that the observed biomarker responses cannot be solely attributed to the petroleum hydrocarbon components of the spilled oil. This first biological effect assessment showed that L. boscii is a potentially suitable target species to be used in future biomonitoring programmes along the northern Iberian shelf.     

Effects of Scotian shelf natural gas condensate on the mummichog

The 96h LC₅₀ of the water soluble fraction (WSF) of natural gas condensate from the Sable Is., N.S. area to Fundulus heteroclitus was between 4 and 5 μg · ml⁻¹ naphthalene equivalents (initial concentration). Behavioural responses in the fish to sub-lethal concentrations of WSF were similar to those recorded for crude and fuel oils. Induction of the hepatic mixed function oxidase enzyme enthoxyresorufin O-de-ethylase (EROD) in sexually immature fish occurred at WSF concentrations below the LC₅₀, but during the prespawning period no induction occurred. EROD activity in unexposed fish showed seasonal variation consistent with differences in its inducibility.     

Evaluation of induction of metallothionein-like proteins (MTLPs) in the polychaetes for biomonitoring of heavy metal pollution in marine sediments

Polychaetes are suitable organisms for evaluation of impact of sediment pollution. We evaluated toxicity of cadmium and copper and measured metallothionein-like proteins (MTLPs) in the polychaete Perinereis nuntia. At the same concentration ranges copper was unexpectedly more toxic than cadmium. Copper also caused no significant increase in MTLPs in the polychaetes. When P. nuntia and another polychaete species, Cirratulus cirratus were cultured in the contaminated sediments collected from Lake Sihwa (Korea), a high mortality of 80% was observed on day 6 in P. nuntia in the sediment with the highest metal concentration. However, no mortality was observed up to 35 days in C. cirratus in any sediment. MTLP contents between two species also varied. These findings suggest that MTLP induction response in the polychaetes varies with the metal type and species and it may be used as a biomarker of sediment pollution in the polychaetes after further validation and field trials.     

Inhibition of phytoplankton photosynthesis by the WSF of used lubricating oil

The photosynthetic rates of five phytoplankton species were inhibited following treatment with the water-soluble fractions (WSF) of used lubricating oil. Exhaust oil from an outboard motor inhibited photosynthesis in three out of the five species tested which indicates a species specific response in the case of this form of oil pollution. Water-soluble fractions from Qatar crude had no inhibitory effect on any of the species tested but had a stimulatory effect on the photosynthetic rate of one species. Both oxygen evolution and carbon assimilation were inhibited by the water-soluble fraction of used lubricating oil. In four out of five species, used lubricating oil WSF caused a net oxygen consumption during the light phase rather than a net oxygen release. These data indicate that used lubricating oil water-soluble fractions are especially toxic to phytoplankton.     

A Comparative Plume Study of DRO,GRO, Benzene,and MTBE: Implications for Risk Management

Groundwater remediation and no-further action decision making at petroleum underground storage tank (UST) sites has largely been based on an understanding of plume length, plume stability, and attenuation rates for key hydrocarbon constituents. Regulatory guidance to support and guide such decisions is based in part on plume studies involving individual hydrocarbon constituents, namely benzene and methyl tert-butyl ether (MTBE). Questions remain regarding whether current guidance is applicable to chemical mixtures such as gasoline range organics (GRO), diesel range organics (DRO), and oxygen containing organic compounds (OCOCs) resulting from hydrocarbon biodegradation. To help address this concern, data from California's GeoTracker database were used to estimate maximum plume lengths, plume stability, and attenuation rates of DRO (which can be used as an analytical surrogate for OCOCs) and GRO relative to benzene and MTBE. The distributions of maximum plume lengths were similar for the four constituents with medians ranging from 27 to 32 m. The fraction of monitoring wells with a decreasing concentration trend ranged from 19% for DRO to 40% for MTBE, while fewer than 7% of the wells had an increasing concentration trend for any of the constituents. Median attenuation rates ranged from 0.10% day⁻¹ for DRO to 0.17% day⁻¹ for MTBE. The results suggest attenuation based risk management is appropriate for DRO and GRO plumes at most petroleum UST sites.     

Gonadal histology and serum vitellogenin levels of bigeye tuna Thunnus obesus from the Northern Pacific Ocean--absence of endocrine disruption bio-indicators

Endocrine disrupting chemicals such as organochlorines have been detected in a large number of marine fish. Histological observation of the gonads, measurement of serum vitellogenin (VTG) level and of liver polychlorinated biphenyl (PCB) content were performed to evaluate the reproductive health and the contamination with endocrine disruptors in bigeye tuna Thunnus obesus, collected in the northern Pacific Ocean in 1999 and 2000. Abnormalities commonly found in species affected by endocrine disruptors such as the presence of oocytes in the testis or elevated serum VTG levels were not found in any of males examined. Both males and females had only small amounts of liver PCB content. The results suggest that currently there is little if any risk of organochlorine contamination or endocrine disruption of gonadal function in bigeye tuna from the northern Pacific Ocean. However, further studies are necessary to evaluate the health status of the open sea fishery resources.     

Evaluation of induction of metallothionein-like proteins (MTLPs) in the polychaetes for biomonitoring of heavy metal pollution in marine sediments

Polychaetes are suitable organisms for evaluation of impact of sediment pollution. We evaluated toxicity of cadmium and copper and measured metallothionein-like proteins (MTLPs) in the polychaete Perinereis nuntia. At the same concentration ranges copper was unexpectedly more toxic than cadmium. Copper also caused no significant increase in MTLPs in the polychaetes. When P. nuntia and another polychaete species, Cirratulus cirratus were cultured in the contaminated sediments collected from Lake Sihwa (Korea), a high mortality of 80% was observed on day 6 in P. nuntia in the sediment with the highest metal concentration. However, no mortality was observed up to 35 days in C. cirratus in any sediment. MTLP contents between two species also varied. These findings suggest that MTLP induction response in the polychaetes varies with the metal type and species and it may be used as a biomarker of sediment pollution in the polychaetes after further validation and field trials.     

Seasonal and pollution-induced variations in biomarkers of transplanted mussels within the Beagle Channel

The occurrence of biomarker variations linked to environmental factors makes it difficult to distinguish the effect of pollution. In an attempt to evaluate spatial and seasonal effects of environmental parameters on biomarker responses, mussels Mytilus edulis chilensis coming from an aquaculture farm were transplanted to several points within Ushuaia Bay (Beagle Channel) for 6 weeks in summer and winter. Activities of superoxide dismutase, catalase, glutathione-S-transferase and levels of lipid peroxidation were measured in gills and digestive gland. Cu, Zn, Fe, Cd and Pb concentrations were also assessed. Results indicated a significant effect of seasons on biological responses as well as in metal bioaccumulation showing the influence of natural factors such as dissolved oxygen, temperature and food availability. The interdependence of those environmental factors is important for the homeostasis of thermoconformers, especially regarding their oxidative metabolism and should also be taken into consideration to distinguish natural from pollution-induced variations.     

Impaired osmoregulation in the shrimp Palaemon adspersus exposed to crude oil extract

Palaemon adspersus is a hyper- and hypo-osmoregulating shallow-water shrimp. For a maximum period of 34 days P. adspersus were exposed to 20, 70, 100 and 200 ppb WSF of North Sea crude oil. The osmotic concentration of the haemolymph was measured by freezing point depression once a week. The ability to maintain hyper-osmolality was significantly decreased (p<0.05) after one, two and three weeks exposure to 200, 70 and 100 ppb, respectively. No effect was observed in 20 ppb. After an accidental exposure of shrimps to 24 h acute oil pollution, they were placed in pure sea water. The ability to maintain hyper-osmolality was reduced one week after the accidental oil exposure, but was regained within three weeks.     

Use of brGDGTs in surface geochemical exploration for petroleum —A case study of oil and gas fields in the Jiyang depression

Branched glycerol dialkyl glycerol tetraethers(brGDGTs),likely produced by bacteria in soil and peat,are widely distributed,easily detected,newly adopted biomarker compounds.In this study,brGDGTs were used to explore the relationship between the absolute abundance of brGDGTs and the distribution of oil and gas fields in the Duoshiqiao area of the Jiyang depression.The results showed that the concentrations at the Xiakou fault and in the oil and gas fields were obviously higher than those in the contrast areas.The clear relationship among the concentration of brGDGTs,the distribution of oil and gas fields,and the acidolysis hydrocarbon(ethane)indicates that the concentration effectively responds to hydrocarbon seeps from the oil and gas field below.brGDGTs may become some of the most important indicators in surface geochemical prospecting for oil and gas.     

Hydrocarbons in surface sediments from the Sfax coastal zone, (Tunisia) Mediterranean Sea

The Semi-enclosed Mediterranean Sea records various signals of high anthropic pressures from surrounding countries and the industrialized European countries. This is particularly true for oil pollution. Although accounting for 1% of the world's ocean surface, it receives about 25% of the petroleum inputs to the ocean. To achieve a global budget we need to collect information from different parts of the Mediterranean. Particularly, we focus in this paper on the Southern Mediterranean, where data are presently very scarce. In this context, the University of Sfax has undertaken an estimation of hydrocarbon pollution along the coasts of Sfax and Gabès Gulf. Non-aromatic hydrocarbons were analysed in 8 surface sediments by FT/IR and GC/MS. Non-aromatic hydrocarbon concentrations vary in the range 310-1406 microg g(-1) sediments dry weight, which is high, compared to other Mediterranean sites. GC/MS data indicate a large group of unresolved compounds suggesting a petroleum contamination, confirmed by the identification of hopanes with predominant C29 and C30alpha,beta compounds and steranes with predominance of C27 over C28) and C29 compounds.     

武汉市东湖沉积物重金属与城市污染环境的关系

应用主成份分析原理,按照主成份提取的信息超过原始信息84％的原则,对武汉市东湖的主体湖区(郭郑湖和塘林湖)的0 cm-7 cm的沉积物30个代表性样品12种元素进行分析,确定其沉积物的重金属的污染源的主要类型．结果表明,郭郑湖第一污染源(占56％)为湖区周围的工业燃煤尘埃,其次(占16％)为交通尾气、生活污水和雨水片流,再次 (占12％)为电镀、印刷等行业的工业污水．塘林湖第一污染源(占65％)为湖区周围的生产性煤燃烧的粉尘,其次(17％) 为生活污水、医院污水和周围土壤的淋溶作用,再次(占9％)为废旧电池、报章杂志和农用物资等．采用均方根综合污染指数法评价分析东湖主体湖区的沉积物的污染程度为轻度污染,其中郭郑湖的污染程度高于塘林湖．     

Mathematical modeling of oil hydrocarbon transformations in different parts of the White Sea

The available observational data on variations of oil hydrocarbon concentrations in White Sea tributaries and in individual parts of the sea are analyzed, and the contributions of different external sources to marine environment pollution are evaluated. The results of calculations are used to determine the possible total input of hydrocarbons from additional potential sources—internal natural (production by microorganisms) and external anthropogenic (navigation and sea shipping), which are most active in the summer and autumn. The hydroecological CNPSi-model is used to reproduce the processes of pollution of nine areas in the White Sea by oil hydrocarbons and their subsequent biodegradation in the marine environment. The annual dynamics of hydrocarbon concentrations was calculated using the long-term annual observations of monthly variations of the temperature, light intensity, and transparency of water, data on the morphometry of sea areas (the squares, mean depths, and water volumes) and water exchange between the chosen areas, calculated by a hydrodynamic model. For large bays (Dvina, Kandalaksha), the calculated concentrations of oil hydrocarbons are shown to be in agreement with the available estimates (the mean and maximal concentrations). The annual variations of oil hydrocarbon concentrations; the biomasses, oxidation activity and bioproduction characteristics of oil hydrocarbon-oxidizing bacteria are characterized. The calculated internal fluxes of oil hydrocarbons (the inputs from different sources, horizontal transport, and biotransformation) were used to calculate their annual balances for individual areas and the sea as a whole, showing the balanced character of their fluxes with the total balance discrepancies for individual areas varying within 0.3–4.1%.     

Mathematical modeling of marine environment pollution processes by petroleum hydrocarbons and their degradation in Caspian Sea ecosystem

The available observational data on the pollution of tributaries and areas of the Caspian Sea by petroleum hydrocarbons and products are examined. The possible petroleum input from sources in the sea is assessed using up-to-date data of satellite observations of sea surface pollution by oil films. The hydroecological CNPSi-model is applied to studying water pollution processes by petroleum hydrocarbons in ten areas chosen in the Caspian Sea and the subsequent biodegradation of those pollutants. The model calculations of the within-year dynamics of petroleum hydrocarbon concentrations use mean annual observational data on within-year variations in water mediium characteristics (water temperature, light intensity, and transparency), as well as the morphometric parameters of sea areas (the area, mean depth, and water volumes). The characteristics of water exchange between the areas were evaluated using a hydrodynamic model. The model calculations were used to characterize the within-year variations in petroleum hydrocarbon concentrations, the biomasses of petroleum-oxidizing bacteria, the characteristics of their oxidation activity and bioproduction, and the internal fluxes of petroleum hydrocarbons (their input from various sources, horizontal and vertical transport, and biotransformation) in different sea areas. Calculation results were used to compile annual balances for the processes of input and consumption of petroleum hydrocarbons in the chosen and aggregated sea areas.     

Evaluation of brine discharge to rivers and streams: Methodology of rapid impact assessment

Induced by a brine discharge study for a submerse gas storage cavern project, a suitable methodology for rapid impact assessment had to be found. In this paper a simple stochastic, stationary model is described for assessment of intensity and temporal variability of chloride pollution at the regional scale of the rivershed. Chloride concentration is used as a proxy of salinity. It is assumed to be the result of deterministic process (flow-dependent) and stochastic variation (estimated for boundary conditions and tributaries by an additive error term based on PERT distribution). This approach is suited to conduct Monte Carlo simulations in order to calculate long-time means and percentiles of the prospective in-stream chloride concentration (exposure model). The biocoenoses exposed to this pollution has to be evaluated in terms of chloride tolerance. Herefore Maximum Field Distributions (MFD) of relevant species (aquatic macrophytes, macroinvertebrates, fish) were compiled and merged to Species Sensitivity Distributions (SSDs). Critical aspects of MFD data quality are discussed. Chloride model simulations representing different discharge scenarios provide exposure parameters (e.g. 90th percentile) that can be compared with SSD-derived protection levels (e.g. maximum loss of 10% of taxa) to quantify and evaluate possible adverse effects as well as potential recolonisation in case of load removal. Crosslinks to conservation issues are relevant in the selection and position of rare or protected species in the SSD. As an analysis of the German legal framework and technical guidelines revealed lack of guidance and best practices for such assessment and impact evaluation, recent experience highlights serious needs in applied research.     

Aerial flux of particulate hydrocarbons to the Chesapeake Bay Estuary

Bulk hydrocarbon deposition rates have been measured over a 15 month period at four stations in south-eastern Virginia surrounding the lower Chesapeake Bay. A nearly linear trend of atmospheric particulate deposition was recorded. Deposition rates at the urban station (195 μg m^?2 day^?1) were aproximately three times greater than those recorded for nonurban and coastal locations (mean value 69 μg m^?2 day^?1). The increased levels at the urban location were attributed to localized source inputs. Anthropogenic hydrocarbons accounted for approximately 50% of the total deposition at all stations. Significant biogenic inputs were indicated by the odd/even n-alkane distribution. A minimum flux to the water surface, based on mean nonurban deposition rates (24 mg yr^?1), indicated an annual particulate hydrocarbon flux of +275 metric tons. Little information is available for the comparison of additional source inputs; however, the data reported here indicate that the aerial deposition of hydrocarbons is of the same order of magnitude as the input from municipal wastewater facilities and accidental discharge and is a potentially significant source of hydrocarbon pollution to the Chesapeake Bay Estuary.     

An Assessment of Potential Oil Spill Damage to Salt Marsh Habitats and Fishery Resources in Galveston Bay, Texas

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.     

Metal exposure and biological responses in resident and transplanted blue mussels (Mytilus edulis) from the Scheldt estuary

The Western Scheldt river and estuary is known to be highly polluted as it receives industrial, agricultural and domestic effluents from one of the most populated and industrialised zones in Europe. Aquatic organisms are exposed to pollutants, specifically metals that are present in different environmental phases, e.g. dissolved, suspended material or sediment phases. The objective of this study was to study the relationship that exists between environmental metal levels, the degree of metal uptake by aquatic organisms with the concomitant biological responses. For this purpose the bivalve mollusk, Mytilus edulis, was selected as bioaccumulation indicator organism. Environmental (water and sediment) and mussel samples were collected during the late winter (March 2000) from sampling sites in the Scheldt estuary. Sites were selected to represent a salinity gradient from the mouth of the estuary to the furthest distribution area of mussels upstream in the system. Together with standard water quality parameters (e.g. salinity, dissolved oxygen, dissolved organic carbon, etc.) concentrations of twelve metals were analysed in the water (dissolved and suspended matter) and sediments. Levels of these metals were also measured in the soft tissue of M. edulis, together with concomitant biomarker responses in resident mussel populations at each site. The biomarkers that were included in this study were condition index, scope for growth, survival in air, cell membrane stability, DNA damage, and metallothioneins. Data were subjected to multivariate statistical analysis. The physico-chemical parameters and metals in the environmental samples clustered the sites to reflect the distribution based on the salinity gradient. Bioaccumulation results revealed increased metal uptake along a pollution gradient with the highest metal bioaccumulation occurring at the upstream most sites and therefore closest to the in the industrial activities. However, the biomarker responses clustered the sites in a manner that reflected the influence of combination of internal exposure (bioaccumulation) and external exposure (physico-chemical conditions). These differences in biomarker responses clearly demonstrated were attributed to abiotic factors other than metal pollution alone e.g. localized short-term increases in increased suspended sediment concentrations and decreased dissolved oxygen concentrations.