CHANGES OF PETROLEUM HYDROCARBON IN JIAOZHOU BAY 1984-1988

Petroleum hydrocarbon (PHC) pollution in marine bays has been one of the critical environmental issues in many countries and regions. Jiaozhou Bay is a semi-closed bay in the fast-rowing region in eastern China and has been contaminated by a variety of pollutants after the 1980s. Using investigation data in this bay during 1981-1988, this paper analyzed the temporal, spatial and seasonal changes of PHC. Results showed that PHC contents in surface waters during 1984-1988 were 0.01-0.16 mgL(-1), 0.025-0.124 mgL-1, 0.005-0.122 mgL(-1), 0.014-0.091 mgL(-1) and 0.005-0.178 mgL(-1), respectively. The pollution level of PHC during 1984-1988 was moderate and was changing with seasons due to the variations of source input. Low values of PHC contents during 1984-1988 were all closed to 0.005 mgL(-1), and this value could be considered as the ` background' value of PHC. High values of PHC contents in spring during this period tended to be stable, yet in summer and autumn during this period tended to be increasing. Stream discharge was the major source of PHC, and marine traffic and marine itself were also responsible. The source strengths were still slight/moderate in according to Chinese Sea Water Quality Standard (GB 3097-1997). Stream discharge was one of the major sources of PHC in every year, and the source strengths were increasing along with time. PHC in this bay was mainly input from rainfall runoff. Marine traffic had been one of the important sources since the 1980s, indicated that the oil leaking from marine traffic should be paid attention to. Marine current was also one of the important sources, and the source strengths could be as high as 0.122 mgL(-1). Rainfall runoff was the major force of various pollutants to the marine bay, the source input of PHC was also in order of summer > spring > autumn > winter. This was the major reason to explain the seasonal variations of PHC contents in Jiaozhou Bay. The background value of PHC in the marine bay was 0.005 mgL(-1), and the increase of PHC contents in the ocean could be calculated as 0.122-0.005 = 0.117 mgL(-1). This was the results of the storage of PHC in the ocean. The control and management of anthropogenic source input of PHC in the marine bay were necessary. The outcome of this paper is to identify the major sources, to define the annual change trend and the spatial-seasonal variations, to assess the storage of PHC in the marine bay, and to provide a basis for environmental management decision-making.