Temporal and Spatial Distribution of Petroleum Hydrocarbon and the Pollution in Seawater of the Liaodong Bay

Abstract:

Here we studied the seasonal, temporal and spatial distribution of petroleum hydrocarbon in the Liaoning Bay based on the all-year-around environmental monitoring data in 2013 and 2014. The source and degree of pollution were also analyzed and discussed. The range of petroleum hydrocarbon concentration in seawater was 0.003-0.239 mg/L with an average of 0.027 mg/L. The concentration tended to decrease over time and exhibited seasonal fluctuation. Petroleum hydrocarbon concentrations in spring, autumn and winter exceeded the limit of the national benchmark with varying degrees. There was a significant correlation between concentrations in the surface and bottom seawater. The petroleum hydrocarbon concentration varied in seasons (autumn > winter > spring > summer), and gradually decreased from inshore to offshore, and from open areas to protected areas. It could be concluded that regions with petroleum hydrocarbon concentrations of 0.030-0.032 mg/L, < 0.024 mg/L, and > 0.032 mg/L accounted for 27%, 10.9%, 4.5% of the total investigated sea area respectively. The region with a concentration of 0.030-0.032 mg/L had an region of 6960 km2 and was mostly within the northern and western coastal region of the Liaodong Bay. The area with petroleum hydrocarbon concentration below 0.024 mg/L was 2806 km2 and was mainly located in the Dalian harbor seal nature reserve. The smallest area was about 1170 km2 in the western harbor area of the Liaodong Bay. Analysis also showed that seasonal variation in petroleum hydrocarbon concentration was affected by the pollution from fishing vessel operations, and that the major sources of petroleum hydrocarbon were the terrestrial inputs and marine anthropogenic activities.