Experimental investigations of five different mosses on accumulation capacities of Cu, Pb and Zn

Abstract

Uptake of Pb, Cu and Zn by different epiphytic moss species Floribundaria floribunda (Doz. & Molk.) Fleisch., Taxiphyllum giraldii (C. Muell.) Fleisch. and Thuidium sparsifolium (Mitt.) Jaeg., an epilithic moss Thuidium delicatulum (L.) Mitt. and a leafy liverwort Ptychanthus striatus (Lehm. & Linderb.) Nees. was studied experimentally. The plant bodies were treated with single metal and mixed metal solutions of Pb(NO₃)₂, CuCl₂ and ZnCl₂ at different concentrations ranging from 10⁻¹⁰ to 10⁻² mol L⁻¹. Higher uptake of Pb, Cu and Zn by T. giraldii, T. sparsifolium and P. striatus than by F. floribunda and T. delicatulum was shown in both treatments. Compared with the single metal treatment, the uptake of Zn was very low at higher concentrations in the mixed metal treatment. A slight depletion of Zn was noticed in the long-term exposure. Leaching of naturally accumulated Zn from the mosses and leafy liverwort was also observed when treated with higher concentrated (10⁻⁴, 10⁻² mol L⁻¹) Pb(NO₃)₂ and CuCl₂ solutions. Similarly, the leaching of naturally accumulated Cu was observed in leafy liverwort P. striatus with 10⁻² mol L⁻¹ Pb(NO₃)₂ and ZnCl₂ treatments. However, insignificant changes were observed on naturally accumulated Pb and Cu in mosses. From these experiments, the epiphytic mosses T. giraldii and T. sparsifolium, which have high Cation exchange capacity and large leaf surface area, have been found to be suitable for assessing heavy metal concentration in a moderately or slightly contaminated environment.

Keywords:

• uptake
• mosses
• leafy liverwort
• lead
• copper
• zinc

Acknowledgements

The scholarship provided to K. Shakya by the Nepal Academy for Science and Technology (NAST), Khumaltar, Lalitpur is gratefully acknowledged. We wish to thank the Department of Botany, Amrit campus, Tribhuvan University, Kathmandu and Nepal Bureau of Standards and Metrology, Balaju, Kathmandu for providing laboratory facilities. Sincere thanks are given to Dr Virendra Nath and Dr D. C. Zhang for moss identification.