Ref ID : 6866
R. Hartenstein, E.F. Neuhauser, and J. Collier; Accumulation of Heavy Metals in the Earthworm Eisenia foetida. J.Environ.Qual. 9(1):23-26, 1980
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Conversion of waste-activated sludge into egesta by the earthworm Eisenia foetida resulted in neither an increase nor decrease of 0.1N HCl-extractable cadmium, copper, nickel, lead, or zinc. The addition of 2,500 ppm copper as copper sulfate to activated sludge caused 100% mortality within 1 week, though feeding upon nonamended activated sludges with up to 1,500 ppm copper over several months was innocuous. Amendment of sludge with 10, 50 and 100 ppm Cd as CdSO4 resulted in 3.90-, 2.04-, and 1.44-fold concentrations in the earthworm over the quantities present in the sludge, with a range of 118 to 170 ppm being found on exposure to the highest level for periods of 1 to 5 weeks at 25 degrees C. In field trials with nonamended sludge, however, containing 12 to 27 ppm Cd, biweekly sampling for 28 weeks revealed accumulations in E. foetida ranging from 8 to 46 ppm; control earthworms not exposed to culture media with easily measurable Cd levels contained 0.3 to 2 ppm Cd. Upwards to about 50 ppm Ni, 325 ppm Pb, and 250 ppm Zn accumulated from sludges amended with ionic soluble forms of these metals. In the field, where these metals ranged from 2 to 46, 1 to 53, and 68 to 210 ppm, respectively, an upper concentration of about 50 ppm Ni, 55 ppm Pb, and 250 ppm Zn were found in the earthworm. Distinctions are made between "accumulable" and "concentratable" and a discussion is provided to show that each of the most problematic heavy metals, Cd, Zn, Ni, Pb, and Cu, may accumulate or concentrate in the earthworm.