Uptake and toxicity of arsenic: Bryum dichotomum Hedw. - a case study

Bryophytes have been used widely as biomonitors to map distribution of pollutant concentrations for many years, but their reliability has been questioned. One issue was the variability of uptake capacity within a species. Many potential reasons have been suggested for this, both intrinsic and extrinsic. This paper provides a brief review of arsenic uptake and tolerance within plants, particularly bryophytes, and examines the variability in uptake of arsenic using Bryum dichotomum Hedw, a moss, as a model organism. Samples were used from two sites, one with low and one with high arsenic emission levels. Differences in uptake were noted and it is suggested that these differences are the result of acclimation to exposure levels at the site from which they were removed. This acclimation could be simple hardening common to many plants or genetic differentiation into ecotypes. The findings of this study have implications with regards to the suitability of bryophytes as biomonitors of metal pollution.