TRANSITION-METALS AND THE ABILITY OF SPHAGNUM TO WITHSTAND THE PHYTOTOXIC EFFECTS OF THE BISULFITE ION

Sphagnum cuspidatum Ehrh. (ex Hoffm.) and Sphagnum recurvum P. Beauv. were collected from the bog surface and minerotrophic lagg zones of two relatively remote 'unpolluted' sites in Northern England and North Wales, and two 'polluted' sites in the S. Pennines. In addition, surface peat and surface water samples were taken adjacent to the sample points. Sphagnum recurvum from mire surfaces in the S. Pennines and drainage channels at remote sites was exposed to the phytotoxic bisulphite ion (HSO3-), which subsequently rapidly disappeared from the bathing solution (< 6 h). When the same species, taken from mire surfaces at remote sites, was exposed to HSO3-, a much slower disappearance of this ion occurred. Sphagnum cuspidatum from remote sites showed a similar response. Both became bleached and eventually died. Sphagnum recurvum, growing in the drainage channel at the remote site showed a higher extracellular concentration of transition metals on cation exchange sites; a consequence of a higher concentration of the same ions in these telluric waters. At the S. Pennine sites transition metal concentrations in the surface peat were high. Here, as in the drainage channels at the remote sites, the extracellular metal concentrations imparted to the moss the ability rapidly to remove HSO3- from the growth medium.