Environmental Engineering Reference
In-Depth Information
Crust-like 'metallophyte' lichens are species which colonise metalliferous
habitats that support few, if any, higher plants. Many grow directly on min-
erals, including copper and uranium secondary phosphates and arsenates
from which they may derive nutrition (McLean et al.
1998
; Purvis et al.
2004
;
Haas & Purvis
2006
). Distinctive lichen assemblages occur in upland regions
of the UK and Europe on rocks in environments where copper sulphides
predominate with associated basic secondary copper compounds often with
significant calcium carbonate (CaCO
3
) creating a higher pH environment.
A new community characterised by 'Copper Lichen' (Lecidea inops) was described
from Cu-rich environments in Scandinavia and the UK (Purvis & Halls
1996
).
L. inops was originally described in 1874 from a Swedish copper mine. In the
UK, this rare species is now included on Schedule 8 of the UK Wildlife and
Countryside Act (1981). At Coniston Copper Mines in the English Lake District,
it occurs on malachite (Cu
2
CO
3
(OH)
2
), azurite (Cu
3
(CO
3
)
2
(OH)
2
) and with smaller
amounts of chrysocolla (Cu
2
H
2
Si
2
O
5
(OH)
4
), covelline (CuS) and bornite (Cu
5
FeS
4
)
cementing fractured quartz (Stanley
1979
;Purvis&James
1985
). Psilolechia leprosa
occurs within the same community andwas described frommaterial sampled from
Poldice Mine, Redruth, Cornwall where it grows on north-facing granitic walls of
mine buildings, associated with mortar containing copper minerals (Coppins &
Purvis
1987
). It was subsequently found by Ken Sandell and the author on the first
church they examined (in Oxfordshire) on mortar beneath copper grilles. Psilolechia
leprosa is most frequent on church walls beneath copper lightning conductors
(Purvis
1996
). Churchyards provide havens for different metallophyte species asso-
ciated with various metal structures and their weathering products. Psilolechia
leprosa was later found by P. W. James and one author on volcanic rocks and relict
cloud forests in madeira and the Azores where it was not obviously associated
with copper mineralisation (Natural History Museum lichen herbarium).
Lecidea inops contains the only known British record of the mineral moolooite
(CuC
2
0
4
.nH
2
0(n
0.4 0.7) (Chisholm et al.
1987
)) in which it occurs as vivid
blue crystalline inclusions (
0.5mm) (Young
1987
; Ryback & Tandy
1992
). The
species is most frequent in mountainous regions in Scandinavia and has been
found on rocks and wood subject to irrigation by Cu-bearing ground waters
in Norway and Slovakia (Purvis & James
1985
). Christian Sommerfelt described
the greenish lichen Lecidea theiodes as a species new to science in 1826 from
Norway. The green colour was considered to be due to a lichen acid (the green
rhizocarpic acid), like the 'map lichen' often used in dating studies. Analytical
studies confirmed over 150 years later the green layer contained Cu, possibly as
a Cu-norstictic acid complex (Purvis et al.
1987
). They supported field observa-
tions emphasising the importance of deposition and the reaction between
cations and coordinating ligands in biomass (Purvis
2000
; Haas & Purvis
2006
).
One of the most obvious effects of mineralization on lichens is the strong
rust colour which occurs in many different and unrelated lichenised groups,
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