大庆油田石油开采对土壤线虫群落的影响

选择大庆油田环境一致的6口油井,研究石油开采干扰对土壤线虫的影响。共鉴定出土壤线虫18科15属。食细菌线虫最多,共15属占总数的49.2%,其次为植物寄生线虫共9属,占30.6%,食真菌线虫4属,占17.6%,杂食/捕食线虫2属,占2.6%。其中优势类群为丝尾垫刃属Filenchus和头叶属Cephalobus,占总数的42.5%。常见类群包括13个属,占总数的51.7%。稀有类群15个属占总数的6.34%。土壤的线虫生活史策略以c-p 2所占比例最大,其次是c-p3和c-p 1类群,受油井开采作业等影响,线虫通过大量繁殖来应对环境的干扰与压力。不同油井线虫总数差异不显著,但所有油井线虫总数比对照明显减少(p<0.001)。不同油井线虫群落结构差异不大,各油井线虫富集指数和结构指数表明所有油井线虫受干扰程度较高,土壤食物网趋于退化。随着采样距离增加,线虫总量差异不显著,但线虫群落的物种数量增加,优势度指数和多样性指数逐渐增加。结果表明油井开采对土壤线虫群落有一定的影响,开采距离对线虫群落结构影响较大。

Effectof oil exploitation on soil nematode communities in Daqing Oilfield

The aim of this study was to evaluate the impact of oil exploitation on soil nematode communities. Six oil wells (N4639'30"-4641'0"; E12453'30"-12458'30") were selected in the Daqing Oilfield, away from villages and in a homogeneous environment. The main vegetation is reeds and low grass with coverage of 75%-90%. Soil samples were collected in triplicate at distances of 0, 3, 6, 10 and 30 m from the wellhead and in three directions of radiation. The nematodes in each soil sample were isolated and identified to genus level under an optical microscope. Thirty genera from 18 families of soil nematodes were identified, which included 15 genera of bacterivores, 9 genera of herbivores, 4 genera of fungivores, and 2 genera of omnivore-predator nematodes. Dominant groups were Filenchus and Cephalobus which were 42.5% of the total. Common groups included 13 genera, representing 51.7% of the total. Rare groups included 15 genera, representing 6.34% of the total. The largest proportion of nematodes (71.8% of the total) belonged to the life history strategy c-p 2 guild with lesser proportions of c-p 3 and c-p 1 guilds. The smallest proportion of nematodes was of the c-p 4 guild, representing only about 4% of the total, and c-p 5 guild was not present. Nematodes around the oil well were mostly of the r-strategists, which indicate their relative resistance to environmental stress. Thus, nematodes adapted to the interference and stress of oil exploitation by increased reproduction. Total numbers of nematodes in the soils around the different wells were not significantly different (P>0.05) but were significantly lower than the control (P<0.001). Numbers of herbivores and fungivores between the different wells were not significantly different (P>0.05). Significantly larger (P>0.05) numbers of bacterivores were found in oil well II. The enrichment and structure indexes of nematode communities in all oil wells were less than 50, showing that the degree of interference of each well was high and the soil food-web in the soil tended to be degraded. The community structure of nematodes between the different wells was not significantly different (P>0.05). Total numbers of nematodes at increasing distance from the well were not significantly different, but were significantly lower than in the control (P<0.05). Numbers of bacterivore, herbivore and fungivore nematodes showed no significant differences (P>0.05) at different distances from the well. Numbers of omnivore-predator nematodes were significantly greater (p>0.05) at 30 m from the well than at other distances. However, with increasing distance from the oil well, abundance, the Simpson Index and the Shannon-Wiener diversity index of nematodes gradually increased. The results of this study establish a theoretical foundation for remediation of soils contaminated by oil exploitation.