Journal
JOURNAL OF HAZARDOUS MATERIALS
Volume 416, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.jhazmat.2021.125919
Keywords
Salinity; Upper intertidal zone; Supratidal zone; Petroleum hydrocarbons; Oiled beaches; Hypersaline coastal ecosystems
Categories
Funding
- Canada's Oceans Protection Plan under the MultiPartner Research Initiative of the Department of Fisheries and Oceans, Canada
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The salinity of upper seashores can surpass seawater due to evaporation, potentially inhibiting the biodegradation of oil spills. Under high salt concentrations, the activity of hydrocarbon-degrading bacteria was significantly inhibited, especially for alkanes. This study suggests that occasional irrigation of oiled supratidal zones could support remediation processes by promoting biodegradation.
The salinity of the upper parts of seashores can become higher than seawater due to evaporation between tidal inundations. Such hypersaline ecosystems, where the salinity can reach up to eight-fold higher than that of seawater (30-35 g/L), can be contaminated by oil spills. Here we investigate whether such an increase has inhibitory effects on oil biodegradation. Seawater was evaporated to a concentrated brine and added to fresh seawater to generate high salinity microcosms. Artificially weathered Hibernia crude oil was added, and biodegradation was followed for 76 days. First-order rate constants (k) for the biodegradation of GC-detectable hydrocarbons showed that the hydrocarbonoclastic activity was substantially inhibited at high salt-k decreased by -75% at 90 g/L salts and -90% at 160 g/L salts. This inhibition was greatest for the alkanes, although it extended to all classes of compounds measured, with the smallest effect on four-ring aromatics (e.g., chrysenes). Genera of well-known aerobic hydrocarbonoclastic bacteria were only identified at 30 g/L salts in the presence of oil, and only a few halophilic Archaea showed a slight enrichment at higher salt concentrations. These results indicate that biodegradation of spilled oil will likely be slowed in supratidal ecosystems and suggest that occasional irrigation of oiled supratidal zones could be a useful supporting strategy to remediation processes.
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