The uptake and loss of zinc am) lead by scapania undulata (l) dum, in relation to its use as a monitor

Abstract

Scapania imdulata (L.) was studied in relation to its use as a monitor of zinc and lead pollution. An important characteristic of such a monitor is the sensitivity with which it mirrors change. To investigate this, clumps of the bryophyte were transplanted between sites which differed in their ambient metal concentration. A second lotic bryophyte, Chilescyphus polyanthus (L. ) Corda, var. rivularis (Schrad. ) Nees., was also transplanted to to act as a comparison. The enrichment ratios of zinc and lead were determined for both S. undulata and C. polyanthus var. rivularis. An enrichment ratio can be defined as: the factor by which an element is concentrated by biological accumulation. It is a particulary useful concept in monitoring studies. If the enrichment ratio remains relatively stable, the concentration of a metal in the monitor can be used to assess the past enviromental concentration. The enrichment ratios displayed by S. undulata varied considerably, with an average coefficient of variance of approximately 60%. Three factors were thought to act as possible sources of variation: i) some papulations of S. undulata displayed an increase in the concentration of accumulated zinc and lead irrespective of the ambient concentration; ii) the transplants indicated that the response to changes in the ambient metal concentration was not always rapid; iii) the concentration of zinc and lead increased markedly down the biyophyte stem and therefore the metal concentration of a sample is influenced by the length of stem taken. It would not be possible to use S. undulata accuratey as a monitor of ambient zinc and lead concentrations until the effects of these factors are understood.