Using 234Th disequilibria to estimate the vertical removal rates of polycyclic aromatic hydrocarbons from the surface ocean

摘要: Abstract A novel 234 Th-coupled approach was employed to deduce the vertical fluxes of polycyclic aromatic hydrocarbons (PAHs) through surface waters harbor, coastal, shelf, and pelagic regimes. We found reasonable agreement between these ocean fluxes, based on direct measurements mixed-layer properties, deduced from underlying sediments. Fluxes decreased exponentially away northeastern U.S.A. Source-diagnostic molecular ratios indicate that atmospheric fall-out combustion-derived PAHs continents is dominant source. Despite higher unit area inshore, open represents a large integral sink for PAHs. For example, 60 metric tonnes pyrene we estimate annually become sequestered in western North Atlantic, only ~ 10% deposited coastal while remaining 90% exported farther offshore continental shelf