Kathryn A. Burns

How many years until mangrove ecosystems recover from catastrophic oil spills

Abstract This short review article summarizes the results from long term assessment of an oil spill into a coastal fringe mangrove ecosystem in Panama. The study combined chemical and biological assessment methods to demonstrate that a time period of up to 20 years or longer is required for deep mud coastal habitats to recover from the toxic impact of catastrophic oil spills. This is due to the long term persistence of oil trapped in anoxic sediments and subsequent release into the water column.

The west falmouth oil spill after 20 years : fate of fuel oil compounds and effects on animals

Abstract The barge Florida spilled No. 2 fuel oil into Buzzards Bay, Massachusetts on 29 September 1969. Sediments from five of the original stations were sampled in August 1989 and analysed for fuel oil hydrocarbons. Two subtidal and one intertidal marsh station showed no evidence of fuel oil. One subtidal mud core had traces of biodegraded fuel oil at 10–15 cm. One marsh core contained 10 −6 g g −1 dry wt of weathered and biodegraded fuel oil aromatic hydrocarbons and cycloalkanes at 5–10 cm with lesser concentrations at 0–5 and 10–15 cm. Although present in trace concentrations, these hydrocarbons appear to be slightly inducing cytochrome P4501A in marsh fish ( Fundulus heteroclitus ).

Measurement Of Physiological Energetics (Scope For Growth) And Chemical Contaminants In Mussels (Arca-Zebra) Transplanted Along A Contamination Gradient In Bermuda

Mussels (Arca zebra) were transplanted to two sites in Castle Harbour and five sites along a contamination gradient in Hamilton Harbour, Bermuda. After 11–12 days mussels were sampled for measurement of physiological responses (such as feeding rate, food absorption and respiration rate) and analysis of chemical contaminants in their body tissues (metals, alkyltins, hydrocarbons and their polar oxygenated derivatives and polychlorinated biphenyls). Physiological responses were integrated by means of the energy balance equation and performance was assessed in terms of “scope for growth”. Mussels sampled 50 m from the Castle Harbour “dump site” showed a slight, but not significant (P > 0.05), decline in scope for growth and a slight increase in accumulated contaminants (tributyltin, petroleum hydrocarbons and PCBs) in comparison with the Castle Harbour “reference site”. In contrast, mussels sampled from sites along the length of Hamilton Harbour showed a marked decline in scope for growth (P < 0.05), due to a reduction in feeding rate and an increase in metabolic energy expenditure. This was accompanied by a significant accumulation of contaminants (Pb, tri- and di-butyltin, petroleum hydrocarbons and their polar oxygenated derivatives and PCBs). There was a significant negative correlation between the scope for growth of Arca and the concentration of Pb (r = −0.76), TBT (r = −0.91), aromatic hydrocarbons (r = −0.92) and PCBs (r = −0.95) in their tissues. Arca accumulated petroleum hydrocarbons and their polar oxygenated derivatives to tissue concentrations that were sufficient to explain the recorded decline in feeding rate, through the mechanism of “nonspecific narcosis” (based on relationships established for the mussel, Mytilus edulis). Similarly, tributyltin was accumulated to concentrations that could induce the observed increase in energy expenditure, through the mechanism of uncoupling of oxidative phosphorylation. Toxicological interpretation of the coupled physiological and tissue residue chemistry data therefore indicates that petroleum hydrocarbons and tributyltin are the major toxic contaminants causing the reduction in scope for growth of Arca in Hamilton Harbour.

Sunlight-induced compositional alterations in the seawater-soluble fraction of a crude oil

Abstract Oil released into the sea undergoes immediate compositional changes as a result of processes of volatilization, dissolution, particle adsorption, and microbial and photochemical decomposition. Based on our observation of the molecular composition of oil residues dissolved in subtropical ocean waters, we hypothesized photo-oxidation of alkyl-substituted polycyclic aromatic hydrocarbons (PAH) and heterocyclic aromatics in preference to their unsubstituted parent compounds. As the ratios of alkyl to parent PAH are used to assign sources to contaminant residues in environmental samples, we tested the hypothesis in a controlled experiment: membrane-filtered seawater collected near the island of Bermuda was saturated with a Nigerian crude oil and exposed to natural sunlight in a quartz flask. Comparison with a dark control under otherwise identical conditions served to differentiate between sunlight-induced and microbially mediated decreases in concentration and changes in composition. We conclude on the basis of UV fluorescence, GC-MS, and microbiological data that sunlight-induced oxidation is responsible for the rapid loss of the UV fluorescence signal for total aromatic hydrocarbons and for the preferential depletion of the alkyl-substituted PAH and heterocyclic aromatics. Structure-dependent selectivity in the photo-oxidation of dissolved oil residues may thus result in residual hydrocarbon blends which could be mistaken as originating from incomplete combustion processes.

Hydrocarbons and related photo-oxidation products in Saudi Arabian Gulf coastal waters and hydrocarbons in underlying sediments and bioindicator bivalves

Abstract Saudi Arabian coastal waters near sandy beaches, severely contaminated with crude oil released in Kuwait during the 1991 Gulf War, as well as underlying sediments and a few bivalves, were analysed to assess concentrations and composition of petrogenic hydrocarbon mixtures and structurally related oxidation products. Concentrations of dissolved oil residues determined by UV spectrofluorometry (UVF) near oil deposits on beaches did not exceed 3.5 μg l−1; concentrations dropped to approximately 1/10th of this value a few miles offshore. Gravimetric concentrations of unfractionated lipophilic material extracted from large volumes of seawater at the same stations were up to 10 times those determined by UVF. After chromatography on silica gel, individual petroleum hydrocarbons in the low polarity fractions and oxidation products in the polar fractions were characterized by their spectra (GC/MS) and quantitated by Selected Ion Monitoring (SIM) GC/MS. Concentrations of oxidation products (ketones, aldehydes, alcohols) of aromatic hydrocarbons exceeded those of their parent compounds by more than an order of magnitude. Significant concentrations were also found of the presumably pyrogenic triplett sensitizer anthraquinone. Contributions to polar fractions of water extracts by biosynthesized lipids were negligible. UVF determinations appear to underestimate concentrations of dissolved oil residues, because many oxidation products have lower fluorescence quantum yields than the respective parent hydrocarbons. Their ecotoxicological properties are unknown. Concentrations measured in sediments by UVF ranged from 13 to 540 μg g−1 dry wt and 0.5 to 103 μg g−1 as measured by gas chromatography with flame ionization detection (FID GC). Bivalves ranged from 0.8 to 1.5 μg mg−1 extractable organic matter (EOM) by UVF, and 0.1 to 0.3 μg mg−1 EOM by GC analysis. PAHs were identified in sediment and bivalve extracts by GC/MS and quantitated by SIM GC/MS. None of the relatively water soluble alkylbenzene photo-oxidation products found in water samples nor any higher molecular weight quinones could be detected in sediment extracts. However, ion chromatograms strongly suggest the presence of numerous high molecular weight aromatics in that matrix.

Organic and trace metal contaminants in sediments, seawater and organisms from two Bermudan harbours

Abstract This paper presents the results of chemical analyses of sediments, seawater and selected organisms collected during an IOC/GEEP Workshop held in Bermuda in September 1988. The data show gradients for the trace metals Cu, Pb and Zn in sediments and for petroleum hydrocarbons in sediments and organisms related to point and nonpoint source inputs to the local harbour waters. Evidence for local sources of PAH combustion products and PCBs is presented, although no obvious point sources could be identified. Methods of the organic analyses were expanded to provide an estimate of the relative abundance of hydrocarbon oxidation products compared to the parent hydrocarbon contaminants. Water samples confirmed that the harbours receive inputs of low boiling fuel products in addition to deposition of fossil fuel combustion products. However, in the islands subtropical environment, processes of evaporation, tidal flushing and photo-degradation are rapid enough to prevent significant accumulation of light hydrocarbons in the calcareous sand sediments. Hydrocarbons in sediments were medium and high molecular weight residues, while the bivalve and holothurian “indicator” organisms concentrated the more soluble lighter hydrocarbon and PCB components. Arca zebra displayed bioaccumulation patterns for organic contaminants similar to those known for Mytilus edulis and Perna viridis. The data base was too small to determine the full potential of the benthic feeding holothurians as indicators of contamination, although they accumulated some organic contaminants. Significant proportions of the hydrocarbon residues in all samples were present as oxygenated reaction products, highlighting the need for further research on the bioaccumulation and relative bioactivities of the oxidation products.

The bahia las minas oil spill Hydrocarbon uptake by reef building corals

Abstract We report the analyses of hydrocarbons in the tissues of reef building corals, reef sediments and seawater samples collected in September 1986 as part of the initial impact assessment of a major oil spill in Panama. The patterns of gas chromatograms indicated the oil residues were highly modified in comparison with the oil spilled only 5 months before: volatile fractions and predominant n-alkanes were missing. Oil levels in corals from the heavily oiled areas were 25–50 mg g −1 lipid as measured by UV fluorescence, while corals in control sites showed nearly non-detectable levels (0.1 mg g −1 ). Oil concentrations correlated with coral mortality rates as measured by decrease in area coverage. Concentrations of petroleum hydrocarons in reef sediments were also elevated in areas of high oiling (393 μg g −1 dry wt) compared to control areas (0.1 μg g −1 ). High concentrations of oil in seawater surrounding the contiguous mangroves (5–29 μg I −1 ) imply that leaching of oil from heavily oiled sediments will provide a source of contamination to the coral communities for an unknown time in the future. Modifications in the protein/lipid ratios of coral tissues were evident in these preliminary data indicating that oiling affected the lipid biochemistry of the surviving corals.

Evidence for the importance of including hydrocarbon oxidation products in environmental assessment studies

Abstract To provide evidence for the importance of including hydrocarbon oxidation products in environmental assessment studies, 10 samples of bivalve tissue from Prince William Sound, collected as part of the assessment of the 1989 Valdez Oil Spill were extracted and separated into fractions based on polarity, by normal phase high performance liquid chromatography (HPLC). Each fraction was analysed by ultraviolet fluorescence spectroscopy (UVF) and examined for evidence of the presence of oxidation products of aromatic hydrocarbons (O-PAHs). Fluorescence in the wavelengths characteristic of O-PAHs was present in the bivalve extracts and intensity correlated with the amount of petroleum hydrocarbons as determined by gas chromatography (GC). The percentage of UVF intensity in polar fractions compared to the hydrocarbon fractions ranged from 7–85% and corresponded with degree of weathering the oil residues had undergone as determined by their GC patterns. Thus, although UVF is only a semi-quantitative method, these results support the contention that photo and bacterial degradation processes create a complex assemblage of intermediate oxidation products of hydrocarbons that are bioaccumulated in marine organisms. Analytical methodologies applied to marine monitoring and hazard assessments must be extended to include some of the oxidation products formed from the toxicants spilled into the marine environment.

The Long-Range Transport of Organic Compounds

When we met at the Bermuda Biological Station for Research, our working group addressed the question of the long-range transport of organic compounds first in terms of the individual compound classes. The main groups of compounds we discussed at the NATO workshop had (1) major sources in continental areas, (2) a long enough residence time in the atmosphere to enable species to be transported hundreds to thousands of

Analytical methods used in oil spill studies

Abstract Because of the recent confusion over the concept of ‘legally defensible methods’ for oil spill studies, often believed to be limited to the analysis of specific polynuclear aromatic hydrocarbons by gas chromatographymass spectroscopy, I restate the need for a hierarchical scheme of methods to be used in environmental assessment studies. I illustrate the success of using several complementary methods in tandem with examples from the results of the Bahia las Minas (Galeta) Oil Spill Study, and present further evidence for reasons why methods must continue to be developed for an expanded range of polar oxidation products.