The suitability of using the growth and reproduction of earthworms to evaluate the heavy metal pollution of soils.

• Main Authors: Jung-Chung Liang, 梁容鐘
• Other Authors: Jen-Hshuan Chen
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/21005657088750753548

碩士 === 國立中興大學 === 土壤環境科學系 === 93 === Earthworm is a good biological indicator of soil quality. Using earthworm as a biological indicator could provide the information of the heavy metal bioavailability, however, few research had been done in Taiwan. The OECD (Organization for Economic Cooperation and Development) earthworm toxicity test was used in this study. The earthworm (Eisenia fetida) was incubated in artificial soils with a series of the concentrations of cadmium(Cd), zinc(Zn), copper(Cu), chromium (Cr3+) and nickel(Ni). Survival, biomass, cocoon production, reproduction and metal bioaccumulation of the earthworm (Eisenia fetida) were determined over experimental period. Additionally, the combined effect of heavy metal on earthworm (Eisenia fetida) also was evaluated by the mixture of different concentrations of copper, nickel and zinc (LC50, ⅔ LC50, ½ LC50). The results showed that the median lethal concentration (LC50) of heavy metals for earthworm at 14th day were Cd > 200 mg kg-1, Zn: 1546 mg kg-1, Cu: 785 mg kg-1, Cr3+: 2031 mg kg-1, and Ni: 1254 mg kg-1. The survival, biomass and reproduction of earthworm were declined with the increasing concentrations of heavy metals in the soil. No significantly effect on survival and biomass of earthworm was observed in the monitor concentration of heavy metals. At control concentration of heavy metals, reproduction of earthworm was significantly depressed, although there was no lethal effect for earthworm. It indicated the reproduction was more suitable for evaluation of the degree of heavy metal pollution. Results also showed that earthworm tissue metal concentration were log-linearly to the total soil metal content. Cadmium was the most concentrated by earthworm, due to its bioconcentration factor (BCF) was highest (range from 11 to 45), but for zinc, copper, chromium and nickel the BCF were lower than 1. The 56-days survival percentages of earthworm in mixture treatment, containing copper, nickel, and zinc was lower than other treatments. It indicated that the mixtures of copper, nickel, and zinc were the most toxic to earthworm. In addition, the toxicity of binary heavy metal mixtures containing of copper, nickel, and zinc on earthworm was Cu + Ni > Cu + Zn > Ni + Zn.