Short-term Effects of Low Heavy Metal Contamination on Soil Nematode Community Structure

다국어 초록 (Multilingual Abstract)

Influences of low concentration of heavy metals (As, Cd, Cu and Pb) on the nematode community structure were examined to assess the changes of the soil ecosystem for a short period of time. Notable increases of heavy metal concentration on the experiment soil were found on the maximum and their 4-1x concentration treatment of all heavy metals after 18weeks. Overall abundance of the nematodes increased regardless of kinds of heavy metal and their concentrations. Also there were no significant differences in the nematode abundance among all treatments of heavy metals except the abundance of c-p 4 in the maximum treatment of Pb. The number of nematode genus found in soils treated with heavy metal solutions also increased compared to that of the genus of the initial soils; however, no significant differences in richness were observed among the treatments of all heavy metals. In maturity and diversity indices of the nematode community, no significant changes occurred in the soils treated with heavy metal solutions with a few exceptions such as MI2-5 and ΣMI2-5 for Pb, and MI2-5 for As. Significant decreases of the ecological indices in the treatments with highly concentrated heavy metal solutions were noticed in MI2-5 and ΣMI2-5 for Pb, and MI2-5 for As, respectively. All of these results is supposed that the maturity and diversity of the nematode community may be decreased in soils contaminated with heavy metals such as Pb and As at relatively low concentrations of a short period of time, which may be derived from differential effects of heavy metals at low concentrations on the growth and development of the nematodes with different c-p values and trophic types. In the analysis of food web structure, only structure index (SI) was significantly lowered in soils irrigated with the heavy metal solutions of Pb and As, but enrichment index (EI) and channel index (CI) were not, suggesting that stressful soil conditions might be provided to the soil food web structure governed by direct toxic effects of heavy metals differential to nematode populations with different trophic type sandc-p values. Analyses of correlation coefficients also suggest that the influence of heavy metals at low concentrations, especially by Pb, maybe most prominent on the nematodes of c-p2-5, including fungivores, providing stressful soil environments.