Monsoon effects on distribution of hydrocarbons in water and sediment of Setiu Lagoon

Abstract

Concentration and distribution of hydrocarbons has been examined in water and surface sediment samples from Setiu Lagoon. The effects of monsoon seasons on the distribution of hydrocarbons in water and sediment of Setiu Lagoon were also determined. There are 14 sampling sites in each sampling and 3 times of sampling trips were conducted. Extraction method was used to determine the concentration of hydrocarbons in the samples. Mean value for hydrocarbons concentration in the water was 78.44 ppb, in the range of 47.08 ppb to 125.09 ppb. Mean value for hydrocarbons concentration in the sediment was 428. 7 mg/kg, in the range of 11.86 mg/kg to 1718.56 mg/kg. The concentration of hydrocarbons in sediment was found to exceed the safety level of 100 mg/kg (Marchand et al., 1982, cited by Law and Rahimi,, 1986).Result of statistical analysis showed that the concentration and distribution of hydrocarbons in water and sediment of Setiu Lagoon were not effected by the changes of monsoons (P>0.05). Anyway, hydrocarbons content in the samples of Setiu Lagoon increased during the occurrence of Northeast Monsoon. In comparison to others adjacent waters of the South China Sea, Setiu Lagoon showed higher level of hydrocarbons content. This is most probably due to the aquaculture, fishing, small scale industries, small scale farming, boat building and eco-tourism activities presence in Setiu. The presence of hydrocarbons in Setiu Lagoon may disturb the pristine marine ecosystem in over there.