PARENT SESSION
16 - Oil Pollution & Biodegradation
8:00 AM to 6:30 PM, Monday, 13 May 2002
Exhibition Area

(16-24) Oil pollution and its toxic effects on saplings of Kandelia candel in a mangrove swamp .

Wong, Teresa^*,1, Ke, L.¹, Wong, Y.S.¹, Tam, Nora¹, ¹ Department of Biology and Chemistry

ABSTRACT- Patches of mangroves along the coastline of Southern China are receiving various kinds of anthropogenic pollutants. In one typical mangrove swamp in Hong Kong SAR, a successful mangrove replanting site in the past, 3-5 years old planted saplings of Kandelia candel, a dominant species in the region, were dead. Signs of oil pollution including oil floating on the water and on the sediment, and smell of petroleum oil were noted on the mudflat. The concentrations of total petroleum hydrocarbons (TPH) in surface sediments collected in December 2000 were significantly higher than the uncontaminated ones, in the range of 55.33 to 95.04 g dry weight g^-1. Results on the commonly used diagnostic parameters, including carbon preference index, the presence of the pronounced unresolved complex mixture (UCM), isoprenoids pristane and phytane in all samples suggest that the mangrove swamp had been contaminated by oil. The concentrations of petroleum hydrocarbons in sediments around the root zone of dying saplings (1354.28 g g^-1 for TPH and 620.34 g g^-1 for UCM) were higher than that in surface sediments. Such high concentrations of petroleum hydrocarbon would pose toxic effects on mangrove saplings. Field surveys showed that 25% to 80% of the planted individuals in a sampling area of 100m² died prematurely. The vertical distribution of oil in core sediment samples collected in March 2001 revealed that the top sediments (0-5 cm) had concentrations of TPH (31.41- 32.09 g g^-1) and UCM (22.23 - 26.26 g g^-1) three times higher than that in the three deeper sections (5-10 cm, 10-15 cm and 15-20 cm). These results suggest that oil pollution in the mangrove swamp might be a recent problem and oil might come from illegal discharge of waste-oil from a nearby factory or from accidental oil spills around the Pearl River Delta Region

Key words: mangrove, oil pollution, petroleum hydrocarbons, sediment