Abstract
Due to the heavy fuel oil (HFO) ban in Arctic maritime transport and new legislations restricting the sulphur content of fuel oils, new fuel oil types are continuously developed. However, the potential impacts of these new fuel oil types on marine ecosystems during accidental spills are largely unknown. In this study, we studied the toxicity of three marine fuel oils (two marine gas oils with low sulphur contents and a heavy fuel oil) in early life stages of cod (Gadus morhua). Embryos were exposed for 4 days to water-soluble fractions of fuel oils at concentrations ranging from 4.1 - 128.3µg TPAH/L, followed by recovery in clean seawater until 17 days post fertilization. Exposure to all three fuel oils resulted in developmental toxicity, including severe morphological changes, deformations and cardiotoxicity. To assess underlying molecular mechanisms, we studied fuel oil-mediated activation of aryl hydrocarbon receptor (Ahr) gene battery and genes related to cardiovascular, angiogenesis and osteogenesis pathways. Overall, our results suggest comparable mechanisms of toxicity for the three fuel oils. All fuel oils caused concentration-dependant increases of cyp1a mRNA which paralleled ahrr, but not ahr1b transcript expression. On the angiogenesis and osteogenesis pathways, fuel oils produced concentration-specific transcriptional effects that were either increasing or decreasing, compared to control embryos. Based on the observed toxic responses, toxicity threshold values were estimated for individual endpoints to assess the most sensitive molecular and physiological effects, suggesting that unresolved petrogenic components may be significant contributors to the observed toxicity.
Highlights
Due to continuous withdrawal of the Arctic sea ice, there has been and will continue to be increased maritime activity and transportation in the Arctic region
The total water accommodated fractions (WAFs) concentrations measured as the sum of volatile organic components (VOC, C5 - C9) and total extractable ma terial (TEM) differed significantly
The Low energy WAF (LE-WAF) of the three fuel oils differ in their chemical compo sition and total WAF concentrations measured as the sum of volatile organic components (VOC, C5 - C9) and total extractable material (TEM) differed significantly
Summary
Due to continuous withdrawal of the Arctic sea ice, there has been and will continue to be increased maritime activity and transportation in the Arctic region. New international regulations restricting the sulphur content of fuel oils onboard vessels have driven the refinery industry to manufacture new fuel products that comply with international, as well as local, policies As these different products have varying chemical, physical and toxicological properties, their fate and potential effects in the environment in the event of accidental spills will inevitably vary. The low sulphur-requirements from the MARPOL Convention have led to new fuel products entering to the market, and these refined products can be light distillates, heavy dis tillates or residual fuel oils, varying tremendously in terms of physical, chemical and toxicological properties They need to be compliant with regulations for the area they are being transported, so for the Svalbard area only light distillates (DMA) with
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