Impact of Heavy Metals (Copper, Zinc, and Lead) on the Chlorophyll Content of Some Mosses K. Shakya Æ M. K. Chettri Æ T. Sawidis Published online: 25 October 2007 Ó Springer Science+Business Media, LLC 2007 Abstract The effects of the heavy metals copper (Cu), zinc (Zn), and lead (Pb) on the chlorophyll content of two mosses Thuidium delicatulum (L.) Mitt. and T. sparsifolium (Mitt.) Jaeg., as well as leafy liverwort Ptychanthus striatus (Lehm. & Linderb.) were examined to understand the impact of metal accumulation on the chlorophyll content of mosses and leafy liverwort, which are found only in uncontaminated sites of the Kathmandu valley. These plants were treated with different concentrations of CuCl 2, ZnCl 2 , and Pb(NO 3 ) 2 , ranging from 10 –10 M to 10 –2 M, in isolation and in combination under experimental condi- tions. Metal accumulation in the plant bodies increased with metal concentrations. Cu accumulation showed a significant inhibitory effect on chlorophyll-a, chlorophyll- b, and total chlorophyll in the mosses and the leafy liver- wort. An insignificant decrease in chlorophyll content in both Thuidium species, but a significant decrease in leafy liverwort, was observed after Zn and Pb accumulation. Chlorophyll-a decreased significantly in T. sparsifolium; chlorophyll-b and total chlorophyll decreased significantly in T. delicatulum; and all chlorophyll contents decreased insignificantly in P. striatus after accumulation of Cu+Zn+Pb ions together from mixed metal solution. The ratio of chlorophyll-a to -b decreased more rapidly in both Thuidium species, with higher concentrations occurring when Cu+Zn+Pb ions were together than when Cu, Zn, or Pb ions were alone. This indicated a more destructive effect of Cu metals on the chlorophyll contents of both Thuidium species. High concentrations of Cu are known to activate oxidative damage and alter cell-membrane prop- erties by lipid peroxidation, thereby demonstrating the inhibitory effect on the enzymes involved in chlorophyll production. The greater loss of chlorophyll from heavy- metal accumulation in P. striatus than in T. delicatulum and T. sparsifolium may have been caused by relatively more K + efflux in leafy liverwort than in the mosses, thus indicating their differences in membrane integrity. Mosses have been proven highly suitable for the uptake of heavy metals and also for environmental monitoring because of their specific morphologic and physiologic properties (Brown & Buck 1985; Tyler 1990; Sawidis et al. 1993; Wolterbeek et al. 1995; Markert et al. 1996; Zech- meister 1998; Fernandez et al. 2002; Shakya et al. 2004; Samecka-Cymerman 2005). Their differential sensitivity to airborne contaminants makes them useful in biomonitoring studies of different environmental qualities (Ruhling & Tyler 1970; Pakarinen 1978; Aceto et al. 2003). These plants cannot prevent ions penetrating into their tissues because they have high counter-gradient mechanisms by which they accumulate significant concentrations of metals in their bodies (Carginale et al. 2004; Shakya K., Chettri M.K., Sawidis T., unpublished data). Metal capture takes place mainly by particle trapping, active uptake of anions, passive adsorption of cations, and ion exchange (Puckett 1988). A number of functional groups in bryophytes are capable of binding metal ions on cell walls (Tyler 1990). Even the dead tissues have the ability to bind ions (Tyler 1989; Chettri et al. 1997a). Metal ions are immobilized mainly by the negative charges of the cell walls, and only K. Shakya (&) Á M. K. Chettri Department of Botany, Amrit Campus, Tribhuwan University, PO Box 102, Kathmandu, Nepal e-mail: kumushakya@yahoo.com T. Sawidis Institute of Botany, School of Biology, Aristotle University, Thessaloniki, Macedonia, Greece 123 Arch Environ Contam Toxicol (2008) 54:412–421 DOI 10.1007/s00244-007-9060-y