Trophic-groups composition of nematode community in petroleum-contaminated soil of Liaohe Oilfield

Soil nematode community trophic-group composition in petroleum hydrocarbons and heavy metal contaminated soil was studied in Liaohe Oilfield, whose oil-well sites had received slurry, crude oil and wastewater during their exploitations. Three sampling sites including the new oil-well site (exploited in 2001), old oil-well site (exploited in 1972) and reeqfield (unexploited, as control) were selected, and 4 sub-sites were determined in each sampling site, respectively. Soil samples were taken from 4 layers (0-10 cm, 10-20 cm, 20-30 cm and 30-40 cm) two times (July and October in 2007), and then 96 soil samples were collected. Nematodes extracted from each sample was identified according their feeding habits i.e. Plant parasites (PP), Bacterivores (BP), Fungivores(FF), Omnivore predators (OP). The results showed that BP were the most abundant group in the two oilwell sites nematode community, and their numbers and relative abundances were significantly higher in the two oil-well sites than the reedfield; while FF showed a reverse trend. In comparison with the reeqfield soil nematode communities, the contamination made OP tend to be fewer, even to die away in the two Oilwell-sites soils. Trophic diversity index(TD) were significantly lower in the two oil-well sites in comparison with the reedfield, that indicated that their ecosystems stability might be effected by the complex pollution.