Gladstone, Australia field studies: Weathering and degradation of hydrocarbons in oiled mangrove and salt marsh sediments with and without the application of an experimental bioremediation protocol

This field study was a combined chemical and biological investigation of the relative rates of weathering and biodegradation of oil spilled in sediments and testing the influence of a bioremediation protocol. The aim of the chemistry work presented here was to determine whether the bioremediation protocol affected the rate of penetration, dissipation or long-term retention of a medium range crude oil (Gippsland) and a Bunker C oil stranded in tropical Rhizophora sp. mangrove and Halosarcia sp. salt marsh environments. Permission for the planned oil spills was granted in the Port Authority area of Gladstone, Queensland (Australia). Sediment cores from three replicate plots of each treatment for mangroves and four replicate plots for the salt marsh (oil only and oil plus bioremediation) were analysed for total hydrocarbons (THC) and for individual alkane markers using gas chromatography with flame ionization detection (GC-FID). Sediments were collected at day 2, then 1, 2, 5 or 6 and 12 or 13 months post-spill for mangroves and day 2, 1, 3 and 9 months post-spill for salt marshes. Over this time, hydrocarbons in all of the oil treated plots decreased exponentially, There was no statistical difference in initial oil concentrations, penetration of oil to depth, or in the rates of oil dissipation between untreated oil and bioremediated oil in the mangrove plots. The salt marsh plots treated with the waxy Gippsland oil showed a faster rate of biodegradation of the oil in the bioremediated plots. In this case only, the degradation rate significantly impacted the mass balance of remaining oil. The Bunker C oil contained only minor amounts of highly degradable il-alkanes and bioremediation did not significantly impact its rate of loss in the salt marsh sediments, At the end of each experiment, there were still n-alkanes visible in the gas chromatograms of residual oils. Thus it was concluded that there was unlikely to be any change in the stable internal biomarkers of the oils over this time period. The predominant removal processes in both habitats were evaporation and dissolution, with a lag-phase of 1-2 months before the start of microbial degradation. (C) 2000 Elsevier Science Ltd. All rights reserved

The assessment of vitellogenin as a biomarker of exposure to estrogenic compounds in two Australian perciformes

Vitellogenin (Vtg) is a yolk protein precursor that has been identified as a sensitive biomarker for exposure to estrogenic compounds. We evaluated specific monoclonal and polyclonal antibodies for reactivity with plasma Vtg from two Australian Perciformes, the tropical barramundi (Lates calcarifer) and the temperate black bream (Acanthopagrus butcheri). Blood plasma from 17ß-estradiol exposed (E2) male barramundi (20 mg kg-1) and male black bream (2.5-5.0 mg kg-1) were sent to Biosense Laboratories (Norway) for cross-reactivity testing using their extensive anti-Vtg antibody selection. Indirect ELISA results determined barramundi plasma displayed the highest binding affinities to ND-3G2 (monoclonal-Mab) and PO-1 (polyclonal-Pab). Black bream was most cross-reactive with ND-1C8 (Mab) and PO-2 (Pab). Next, plasma was assessed for Vtg induction in E2-dosed (5 mg kg-1), hatchery-reared barramundi and black bream versus a non-injected control group. Vtg production was assessed by Western blot and indirect ELISA using ND-3G2 and ND-1C8 Mabs, respectively. A prominent band was identified in the range of 100-200 kDa for all female black bream and for all E2-treated barramundi and black bream males, which was confirmed as Vtg by Western blot. Indirect ELISA results for barramundi demonstrated highly significant differences in E2-dosed fish as compared to control fish (Student t, P < 0.001). E2 male black bream were significantly different than control males (Student t, P < 0.001) and control and E2 females displayed highly significant differences (Student t, P < 0.001). These results indicate that exposure to 17ß-estradiol induces significant Vtg production in males of the two Australian Perciformes, with potential use as a biomarker for exposure to estrogenic compounds

Weathering of hydrocarbons in mangrove sediments: testing the effects of using dispersants to treat oil spills

This field study was a combined chemical and biological investigation of the relative effects of using dispersants to treat oil spills impacting mangrove habitats. The aim of the chemistry was to determine whether dispersant affected the short- or long-term composition of a medium range crude oil (Gippsland) stranded in a tropical mangrove environment in Queensland, Australia. Sediment cores from three replicate plots of each treatment (oil only and oil plus dispersant) were analyzed for total hydrocarbons and for individual molecular markers (alkanes, aromatics, triterpanes, and steranes). Sediments were collected at 2 days, then 1, 7, 13 and 22 months post-spill. Over this time, oil in the six treated plots decreased exponentially from 36.6 +/- 16.5 to 1.2 +/- 0.8 mg/g dry wt. There was no statistical difference in initial oil concentrations, penetration of oil to depth, or in the rates of oil dissipation between oiled or dispersed oil plots. At 13 months, alkanes were >50% degraded, aromatics were similar to 30% degraded based upon ratios of labile to resistant markers. However, there was no change in the triterpane or sterane biomarker signatures of the retained oil. This is of general forensic interest for pollution events. The predominant removal processes were evaporation (less than or equal to 27%) and dissolution (greater than or equal to 56%), with a lag-phase of 1 month before the start of significant microbial degradation (less than or equal to 7%). The most resistant fraction of the oil that remained after 7 months (the higher molecular weight hydrocarbons) correlated with the initial total organic carbon content of the soil. Removal rate in the Queensland mangroves was significantly faster than that observed in the Caribbean and was related to tidal flushing. (C) 1999 Elsevier Science Ltd. All rights reserved

Barramundi as an indicator species for environmental monitoring in North Queensland, Australia: laboratory vs field studies

The dose-response relationship for hepatic 7-ethoxyresorufin-O-deethylase (EROD) induction in barramundi (Lates calcarifer) was examined under controlled laboratory conditions for 15 d using farm-reared barramundi. These results were compared with EROD activity measured in barramundi collected from two rivers catchments (impacted and nonimpacted) in northern Queensland, Australia. Barramundi were dosed by intraperitoneal injection with a known cytochrome P4501A (CYP1A) inducer, beta-naphthoflavone (beta-NF), at 5, 10, and 50 mg kg(-1) using two controls: A vehicle control (corn-oil injected) and an experimental control (no injection). The EROD induction occurred within 4 h in the 5, 10, and 50 mg beta-NF kg(-1) exposures, reaching mean maximum activities of 88.6 (+/-51.9), 85.5 (+/-91.7), and 149.1 (+/-106.4) pmol min(-1) mg protein(-1), respectively. Mean EROD activities remained low in the corn-oil controls (2.1+/-1.8 pmol min(-1) mg protein(-1)) and experimental controls (5.3+/-4.4 pmol min(-1) mg protein(-1)) throughout the study. Barramundi demonstrated a rapid response curve, which was dose dependent (50 > 10 > 5 mg beta-NF kg(-1)) and decreased progressively over time from induction. Measurement of total cytochrome P450 content (nmol mg protein(-1)) was not dose dependent. The EROD activities from field-collected barramundi from the Johnstone River (impacted) and Olive River (nonimpacted) suggest exposure to low-level contaminants in the Johnstone River fish only. With more controlled laboratory and field studies, barramundi have the potential to become a major indicator species in assessing exposure to environmental contaminants in coastal areas throughout northern Queensland, Australi

Effects of chlorpyrifos on cholinesterase activity and stress markers in the tropical reef fish Acanthochromis polyacanthus

Tropical coastal ecosystems, including the Great Barrier Reef (GBR) of Australia are increasingly threatened by pollution; yet few studies have investigated the sensitivity of GBR species to these pollutants. Here we exposed juveniles of the tropical reef fish Acanthochromis polyacanthus (spiny damselfish) to three concentrations of the insecticide chlorpyrifos (CPF) and measured (i) muscle cholinesterase (ChE) activity; (ii) hepatic glutathione-S-transferase (GST) activity; and (iii) coenzyme Q (CoQ) redox balance, after 6 h and 96 h of exposure. After 96 h, muscle ChE activity was significantly inhibited by 26%, 49% and 53% when fish were exposed to 1, 10 or 100 μg/L CPF, respectively. Muscle ChE characterization revealed three types of ChEs, including two atypical forms. Hepatic CoQ antioxidant form significantly increased at 10 μg/L after 6 h of exposure, potentially demonstrating an early response to CPF-induced oxidative stress in liver. Hepatic GST was not affected by CPF exposure

Assessing the oil degradation potential of endogenous micro‐organisms in tropical marine wetlands

As part of a larger study on the bioremediation of oil spills in tropical mangrove habitats, we conducted a series of flask experiments to test for the presence of hydrocarbon degrading microdashorganisms in representative wetland habitats. Also tested was the biodegradation of selected oils (Gippsland Crude, Arabian Light Crude and Bunker C), that are transported along the Australian coast. We also tested for potential inhibition of biodegradation by natural organics in the mangrove pore waters and evaluated the ability of an oxygen release compound (ORC) to stimulate biodegradative processes. Evaporation was a significant factor in removing the light alkane and aromatic hydrocarbons from air and nitrogen sparged flasks. Evaporation removed sim27% of the Gippsland, sim37%of the Arabian, and sim10% of the Bunker oils. Oxygen was necessary to support biodegradation as expected. The microdashorganisms were capable of biodegrading the nondashvolatile saturate fraction of each oil. Degradation removed another 14 of the Gippsland, 30 of the Arabian, and 22 of the Bunker C oils. Normalisation of the individual aromatic hydrocarbon classes to internal triterpane biomarkers indicated some degradation of aromatics in the Arabian Light and Bunker C oils. Although alkane degradation rates were comparable in the three oils, the Gippsland oil had a higher wax content and after 14 days incubation, still contained as much as 25 of the alkanes present in the original oil. Thus, degradation of its aromatic fraction may have been delayed. Based on these results we estimate that Arabian Light Crude oil would have a shorter residence time than the other oils in mangrove sediment. It has a higher content of light hydrocarbons, which are readily removed by both physical and microbial processes. The Bunker C would be expected to have the longest residence time in mangrove sediment, because it contains a larger percentage of higher molecular weight, unresolved components. Comparison of the efficiency of inoculates from three tropical intertidal habitats (Avicennia and Rhizophora mangroves, plus salt marsh sediments) indicated the presence of hydrocarbon degrading microdashorganisms in all three habitats. There was no known history of oil contamination in the soil source area. There was no inhibition of degradation due to addition of mangrove pore waters. The ORC did not facilitate degradation in closed laboratory experiments. These results were used to formulate a bioremediation strategy to treat oiled sediments in mangrove forests in Queensland Australia, which was based on forced aeration and nutrient addition. Evaporation was a significant factor in removing the light alkane and aromatic hydrocarbons from air and nitrogen sparged flasks. Evaporation removed sim27% of the Gippsland, sim37% of the Arabian, and sim10% of the Bunker oils. Oxygen was necessary to support biodegradation as expected. The micro-organisms were capable of biodegrading the non-volatile saturate fraction of each oil. Degradation removed another 14% of the Gippsland, 30% of the Arabian, and 22% of the Bunker C oils. Normalisation of the individual aromatic hydrocarbon classes to internal triterpane biomarkers indicated some degradation of aromatics in the Arabian Light and Bunker C oils. Although alkane degradation rates were comparable in the three oils, the Gippsland oil had a higher wax content and after 14 days incubation, still contained as much as 25% of the alkanes present in the original oil. Thus, degradation of its aromatic fraction may have been delayed. Based on these results we estimate that Arabian Light Crude oil would have a shorter residence time than the other oils in mangrove sediment. It has a higher content of light hydrocarbons, which are readily removed by both physical and microbial processes. The Bunker C would be expected to have the longest residence time in mangrove sediment, because it contains a larger percentage of higher molecular weight, unresolved components. Comparison of the efficiency of inoculates from three tropical intertidal habitats (Avicennia and Rhizophora mangroves, plus salt marsh sediments) indicated the presence of hydrocarbon degrading micro-organisms in all three habitats. There was no known history of oil contamination in the soil source area. There was no inhibition of degradation due to addition of mangrove pore waters. The ORC did not facilitate degradation in closed laboratory experiments. These results were used to formulate a bioremediation strategy to treat oiled sediments in mangrove forests in Queensland Australia, which was based on forced aeration and nutrient addition

Toxic contaminants and their biological effects in coastal waters of Xiamen, China. I. Organic pollutants in mussel and fish tissues

Organochlorines and organophosphates were measured in four fish species (Lateolabrax japonicus, Pagrasomus major, Muchthys miiuy and Epinephalus awoara) and the mussel Perna viridis collected from aquaculture cages in coastal waters of Xiamen, China. Polycyclic aromatic hydrocarbon (PAH) metabolites were also measured in fish bile. Sites in Xiamen coastal waters (the harbour, Maluan and Tongan) are compared with a "cleaner" reference site at Dongshan Island. DDT was found in livers of all fish sampled (May 1998, 1999 and December 1999) ranging from 0.15 to 2.2 mug/g WW, but levels in muscle tissue (<0.5 ng/g to 0.22 &mu;g/g WW) were at least an order of magnitude lower in the harbour, and were not detectable (<0.5 ng/g) in Tongan samples. All other pesticides examined were not detected in fish or mussels, except for dieldrin in one liver sample (0.07 mug/g WW). Food of the caged fish, small fish and dried pellets, had very low (0.015-0.027 mug/g WW) or non-detectable levels of DDT, indicating significant bioaccumulation of contaminants in caged fish and/or other possible sources of uptake (water and sediments). DDT levels in fish varied with species. DDT contamination in fish livers and whole mussels varied significantly with location. Highest concentrations in fish occurred in the harbour, and less consistently so in Tongan. Dongshan and Maluan had comparatively low levels of DDT. Relatively low residues of DDT in both fish and mussels at Dongshan likely reflect lower levels of pesticide input at this reference site. However, the low levels of DDT contamination in fish tissues from Maluan were unexpected in view of the close proximity of the harbour and possibly reflect the removal of particulate-bound contaminants by the intensive bivalve culture there. Consistently high proportions of DDT in the form of the parent compound (p,p'-DDT: fish 30-45%; mussels 40-65%) from all sites suggest recent releases of this chemical to the environment. Levels of two main groups of PAH metabolites (naphthalene and phenanthrene) in fish bile suggest a different environmental distribution pattern than that of pesticides, in that Dongshan fish appear to be no less exposed to hydrocarbons than those from Xiamen coastal waters. (C) 2002 Elsevier Science Ltd. All rights reserved