An oil spill accident and its impact on ozone levels in the surrounding coastal regions

An oil spill on the west coast of the Republic of Korea was investigated with regard to its impact on ozone (O3) concentration levels in the surrounding regions. The accident occurred on December 7, 2007 with the total estimate of 12,500 tons of Iranian Heavy plus Kuwait Export crude oils. The evaporation rates of the volatile hydrocarbon fractions in these crude oils were estimated based on the molar fractions of crude oils and their mass transfer coefficients. Their emission rates parameterized with several key environmental parameters (e.g., wind speed, seawater temperature, and salinity) along with oil type information were then applied in the 3-D chemical transport model. Photochemical production of O3 in winter just after the accident was relatively insignificant due to very low photochemical activity. For the case/sensitivity study, the photochemical production of O3 simulated under the hot summer weather conditions was predicted to be significant at the same magnitude of the oil spill. This study confirms that an oil spill, if occurring around coastal regions, can alter O3 levels to a large extent depending on the meteorological conditions.

Research highlights
► We estimate the impact of oil spill at the west coast on O3.
► Its largest impact on O3 was predicted to be in the downwind areas by 9 ppb.
►  Advection is generally a main contributor to O3 concentration change.
► O3 production rate for RO2 + NO was higher than that for HO2 + NO.