Cadmium and Lead Accumulation in Three Endogeic Earthworm Species
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Cadmium and Lead Accumulation in Three Endogeic Earthworm Species Robabeh Latif • Masoumeh Malek Hassan Mirmonsef
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Received: 17 August 2012 / Accepted: 15 December 2012 / Published online: 3 January 2013 Ó Springer Science+Business Media New York 2012
Abstract The objective of this study was to assess the capability of earthworms from the same ecological group as heavy metal bioindicators. Three earthworm species from the endogeic group were studied: Aporrectodea caliginosa (Savigny, 1826), Perelia kaznakovi (Michaelsen, 1910) and ¨ rley, 1885). Their accumulation of the Octolasion lacteum (O heavy metals lead (Pb) and cadmium (Cd) were studied from three stations in Tehran province, Iran. O. lacteum was used to compare metal accumulations in two sites located next to a highway. A. caliginosa and P. kaznakovi were used at a third site located near the edge of a sewage system to compare metal accumulations between the two endogeic species in this area. At both locations, the concentrations of Cd and Pb in earthworms were higher than in the surrounding soil. The results of the study revealed that P. kaznakovi and A. caliginosa were better bioindicators for Pb, but O. lacteum was a better bioindicator for Cd. These earthworms can therefore be used as Cd and Pb bioindicators in environmental assessment. Keywords
Earthworms Bioindicators Cadmium Lead
Introduction As the amounts and types of contaminants in our environment continue to increase, the contamination of soil has become a real concern in recent times. Heavy metals, including lead, cadmium and mercury, are among those contaminants. Depending on their susceptibility, certain
R. Latif M. Malek (&) H. Mirmonsef School of Biology, College of Science, Center of Excellence in Phylogeny of Living Organisms, University of Tehran, Tehran, Iran e-mail: [email protected]
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organisms that are in continuous contact with their environment concentrate metals in their tissues, a process called bioaccumulation. Some invertebrates, such as snails and earthworms, which are major components of the soil macrofauna, can be used to monitor the ecosystem. Earthworms are suitable for biomonitoring ecosystems for the following reasons: they are large, numerous, easy to sample and identify (Fru¨nd et al. 2010), and less mobile than some other organisms (Paoletti 1999). In addition, earthworms are eaten by other organisms such as birds, so the accumulated metals also affect higher trophic levels, such as some birds and mammals (Greig-Smith et al. 1992). According to Nieboer and Richardson (1980), the group of metals which can act as toxicants for earthworms bind to nitrogen or sulphur. The other group members bind to oxygen and serve a role as macronutrients. Cd and Pb are included in the first group. Notable correlations were found between concentrations of Pb, Cu, and Zn in soil and in earthworm tissue by Neuhauser et al. (1995). Each species, even where closely related, recruits different mechanisms to accumulate metals, which results in variations in the amount
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