Real-time Water Column Hydrocarbon Mapping Using The Battelle Ocean Sampling System (BOSS) To Identify Chronic And Spilled Oil Inputs To The Coastal Marine Environment

Petroleum hydrocarbons enter the marine ecosystem from a variety of sources including industrial and domestic sewage discharges, surface runoff, creosote discharges from pier pilings, atmospheric deposition and oil spills. The analytical costs associated with traditional GC/FID and GC/MS hydrocarbon measurements often limit the number of samples collected and analyzed for hydrocarbon fate and transport studies resulting in a loss of spatial resolution. The ability to monitor petroleum hydrocarbons in coastal water columns using real-time detection systems provides improved spatial analytical resolution without excessive analytical costs. These tools can be used to identify chronic coastal inputs and track subsurface oil transport during an oil spill. Sampling sites for traditional water sample collection and analysis can be designated based on criteria developed wing the real-time analytical system. This approach will reduce overall analytical costs by screening out the areas with little or no hydrocarbons, and target the collection of selected water samples from contaminated areas. Discrete water samples can then be: analyzed by GCjFID and GC/MS methods and used to Calibrate the real-time hydr'ocarbon detection system. In this paper, we present the results of a study where real-time water column hydrocarbon measurements were combined with discrete laboratory analytical measurements to develop a hydrocarbon distribution map. An integrated sampling system made up of an underwater sensor unit and pumping system has been developed to provide realtime in situ salinity, temperature, and depth measurements and continuous water samples for onboard fluorometry (excitation 254nm, emission 350nm). Discrete water samples were collected and analyzed for aliphatic and total hydrocarbons by GC/FID and aromaitic hydrocarbons by GC/ MS. Low analytical detection limits (saturated hydrocarbons 0.2 pg/l, total hydrocarbons 10 pg/l, and aromatic hydrocarbon 10 ng/l) were required to monitor the hydrocarbon distributions in these samples. These measurements were used to Calibrate the real-time fluorometry measurements and develop a coastal hydrocarbon input map. The effectiveness of this analytical approach to delineate chronic and oil spill inputs to marine waters will be discussed.