PETROLEUM HYDROCARBON CONTAMINATIONS IN INTERTIDAL SEAWATER AFTER THE HEBEI SPIRIT OIL SPILL EFFECT OF TIDAL CYCLE ON THE TPH CONCENTRATIONS

Abstract

In December 2007 the oil tanker Hebei Spirit released about 12,547 kilo liters of crude oil into the west coast of Korea, heavily impacting more than 70 km of coastline of Taean County. Total petroleum hydrocarbons (TPH) in seawater was monitored using a gas chromatograph / flame ionization detector (GC/FID) to understand the contamination levels and temporal variations of dissolved/dispersed oil in intertidal seawater. An extensive sample collection campaign was initiated at the impacted sites five days after the spill, and subsequent monthly-based surveys were continued until December 2008. TPH concentrations in seawater, immediately after the spill (December 12 좻 16, 2007), ranged from 1.22 to 106,000 꺷g L-1 with an average of 1,540 꺷g L-1 (n=92) and appeared to decrease dramatically to 1.98 좻 172 꺷g L-1 in one month after the spill. The TPH concentrations in seawater fluctuated with time thereafter, because of the remobilization of oil by continuing shoreline cleanup activities and wave/tidal actions. Seawater TPH concentrations were much higher on the flood tide due to re-suspension of stranded oil than on the ebb tide at the same sites. The variation of TPH levels in seawater also matched well with the spring-neap tidal cycle in the study areas for the first three weeks after the spill. The one year monitoring revealed that oil content in seawater had decreased clearly at most sites, although some regional fluctuations of oil contamination were noted until June 2008.