Ecophysiological effects of high concentrations of iron and other heavy metals on Eriophorum angustifolium Honck. and Phragmites australis (Cav.) Trin ex steudel.

Little is known of the effect of high concentrations of
heavy metals on the growth of wetland plants, although it is
has long been suggested that adaptation to waterlogged
anaerobic environments involves the capacity to exclude
dissolved iron.
This work investigates the chemical dynamics of selected
metal toxins, in particular Fe in relation to concentration
in the substrate and uptake b y Eriophorum augustifolium, and
Phragmites australis taken from mine populations (Parys
Mountain, Anglesey and Crymlyn Bog , Swansea) and a non-mine
population (Skipwith Common, Yorks) and to provide
information on the resistance of these two species to high
concentrations of Fe and other heavy metals.
Both field and laboratory work have been used to focus
on the above areas. The first part of the study is based on
the analysis of plants and soil samples collected from the
field and relates heavy metal concentration in plant tissue
to concentrations in soil/sediments. The second part of the
study is based on laboratory work to determine individual
factors influencing heavy metal uptake and resistance in the
study species.
Fe, Mn, Cu, Zn and Pb concentrations in plant tissues
reflected those in the soil. Seasonal fluctuations in metal
concentration in plant tissues were observed but the bulk
differences were related to soil heterogeneity between
sites.
In culture solutions, Fe uptake in both species
increased with increasing Fe supply. E. augustifolium from
the Parys site was less sensitive to hi g h Fe concentrations
relative to plants from the Skipwith site. Fe-uptake by E
angustfolium, was strongly influenced by pH. Fe--uptake by
plants was unaffected by the presence of Fe-plaques on roots.
A relationship between Fe and P is highlighted
enhancing P availability to plants of E. augustifolium in
th presence of 100 mg /l Fe by treating half the roots
with Fe and the remaining half with 0.1-strength Rorison
solution with 1 mg/l Fe, stimulated root oxidation of Fe and
the accumulation of Fe-plaque, reducing translocation
of Fe to shoots. P].ants of the same species with
Fe-plaque an the roots accumulated more P than plants without plaque, the bulk of this P was immobile.
E. angustifolium from the Parys Mountain site was
found to be more tolerant to Cu but more sensitive to Mn, the
reverse was true for p).ants from the Skipwith site. The imp1ications of this work in relation to plant
growth and resistance to heavy metal—enriched environments
are discussed. It is suggested that both species may be
constitutionally tolerant to Fe and Mn. Plants from the Parus
site may be more resistant to high concentrations of Cu, Zn
and Pb.