Effect of tidal cycle on the total petroleum hydrocarbon concentrations in intertidal seawater after the Hebei Spirit oil spill

Abstract

In December 2007 the oil tanker Hebei Spirit released about 12,547,000 liters of Middle-East crude oil into the west coast of Korea, impacting more than 375 km of coastline. Total petroleum hydrocarbon (TPH) in seawater was monitored using GC/FID to understand the contamination levels and temporal variations of dissolved/dispersed oil in the intertidal seawater. TPH concentrations in seawater, immediately after the spill, ranged from 1.5 to 7,310 µg/L with an average of 732 µg/L and appeared to decrease drastically to 2.0 – 224 µg/L in one month after the spill. Seawater TPH concentrations were much higher on the high tide than on the low tide at the same site due to re-suspension of stranded oil during the flooding of intertidal zone. The variation of TPH levels in seawater also matched well with the spring-neap tidal cycle in the study area for the first three weeks after the spill. This result highlighted the need to control seawater sampling time for petroleum pollution study especially at high-tidal range areas and at the early stage of oil spill. This result also implies that sessile organisms at the upper and lower intertidal zone are possibly exposed to different levels of oil concentrations in seawater.ing GC/FID to understand the contamination levels and temporal variations of dissolved/dispersed oil in the intertidal seawater. TPH concentrations in seawater, immediately after the spill, ranged from 1.5 to 7,310 µg/L with an average of 732 µg/L and appeared to decrease drastically to 2.0 – 224 µg/L in one month after the spill. Seawater TPH concentrations were much higher on the high tide than on the low tide at the same site due to re-suspension of stranded oil during the flooding of intertidal zone. The variation of TPH levels in seawater also matched well with the spring-neap tidal cycle in the study area for the first three weeks after the spill. This result highlighted the need to control seawater sampli