Aquatic cryptogams of natural acid springs enriched with heavy metals:
the Kootenay Paint Pots, British Columbia
J. D. Wehr & B. A. Whitton'
Department of Botany, University of Durham, Durham DH1 3LE, England
1 Author to whom correspondence should be sent.
Keywords: acidity, iron, zinc, algae, Cephalozia bicuspidata, Dicranella heteromdla
Abstract
An account is given of the chemistry and aquatic cryptogams of the Kootenay Paint Pots, British
Columbia. The waters fell in the pH range 3.2 to4.0, were mostly anaerobic and had high levels of Fe and Zn.
Fourteen species of algae, one liverwort (Cephalozia bicuspidata) and one moss (Dicranella heteromalla)
were found in the various springs and pools. The two dominant Chlamydomonas species existed as
palmelloid growths where they occurred among sediments, while Dicranella heteromalla occurred everywhere only as protonema. The flora is different in mary respects from that of typical acid mine drainages, the
Dicranella being the only one of eight common species in such drainages represented. Most of the photosynthetic organisms in the Paint Pots must tolerate anaerobic conditions for long periods and it is suggested that
this may be a key factor explaining the floristic difference.
Introduction
The study of organisms in highly acidic environments has largely centred on three types of environment: acid mine drainages (e.g. Lackey 1938),
thermal acid springs (e.g. Brock 1978) and lakes
(e.g. Negoro 1944). The waters of the first, but
usually not the other two types, are usually also
strongly enriched with heavy metals and provide a
particularly specialized environment for organisms
t o colonize. Natural examples of highly acidic
drainages enriched with heavy metals appear t o be
rare, but the Kootenay Paint Pots in British Columbia provide a particularly interesting example
whose geochemistry has been described by Van
Everdingen (1970). His extensive studies showed
that the acidity was due to the oxidation of sulphide
ores and that the waters of the various springs
contained very high levels of heavy metals, particularly iron and zinc. Similar phenomena have been
described for acid waters draining from coal mining
areas by many authors (e.g. Hanna et al. 1963).
Hydrobiologia 98.97105 (1983). 0018-8 l58/83/0982-0097/$OI.80.
o Dr W. Junk Publishers, The Hague. Printed in the Netherlands.
This unusual parallel in a naturally occurring
system offers a valuable comparison with acidic
environments which result from man's activities.
The Paint Pots have, for instance, probably provided an environment available for colonization
since the last Ice Age (ca 10 000-15 000 years BP).
The present study of the chemistry and photosynthetic cryptogams of the Paint Pots was made to
examine possible similarities and differences with
acid mine drainages resulting from man's activities
during the last couple of centuries.
Methods
Field
Measurements of physicochemical variables in
situ and collection of samples were made during
16- 17 July 1979. Temperature was measured with a
mercury thermometer, conductivity with a Yellow
Springs Instrument Co. salinity-conductivity me-
ter, pH with a Markson model 85 meter and O2 by
use of the azide modification of the Winkler titration (American Public Health Association, 1971).
Collection of water for metal analysis followed methods described in Holmes & Whitton (l981), with
the exception of the type of filter. Because of the
large amounts of suspended particulate matter, filtration was carried out using Whatman G F / C glass
fibre filters (c. 2 p m pore size). T h e samples were
preserved with atomic absorption grade H N 0 3 .
Sediments and aquatic bryophytes were collected
and stored for metal analysis according t o Say et al.
(1981).
The sites used for sampling organisms were as far
as possible chosen t o coincide with those studied by
Van Everdingen (1970). Algae and aquatic bryophytes were collected from designated reaches in
streams as described by Holmes & Whitton (1981).
Samples from the pools of the springs were taken by
(i) collection of mud with a perspex tube (5 mm
internal diameter) after the method of Round
(1953) and (ii) plankton tows using a Wisconsin
style nFt (no. 25 mesh). One half of each of the
samples wa y preserved with Lugol's iodine, while
the other half was kept alive. T h e latter and all
water samples were stored in a n ice chest until
return to the laboratory two days later.
N) as a nitrogen source; use of 8.5 p M ethylenediaminetetra-acetic acid as a chelator. Some cultures
were also maintained with added zinc ( l , 2 , 5 , 10 mg
I-') additional to that (0.04 mg 1-I) present in the
medium. No attempt was made to simulate the
anaerobic conditions found in the field.
Taxonomy and morphology
Most of the species were identified from preserved samples, although some were brought into
the laboratory for further observation. This was
essential for Chlamydomonas spp., as these were
usually present in the field as palmelloid sheets. In
culture two species were recognized 'from all sites.
Both were motile during the logarithmic growth
phase. Once growth had reached a plateau, the cells
lost their flagella, but did not form palmelloid
masses. The moss Dicranella existed only as protonema until brought into culture, when it produced
leafy shoots when grown without added zinc. The
growth form of the liverwort Cephalozia was unaffected by concentrations up t o 10 mg I-' Zn. There
was no apparent difference in the morphologies of
the algal species over the zinc range used.
Study area
T h e washing, processing and digestion procedures of both sediments and bryophytes followed
that described by Say et a/. (1981), with the exception that whole plants of bryophytes were used for
metal analysis because of their small size (<1 cm in
length). Metals in these materials and water were
analysed by atomic absorption spectrophotometry
(Perkin Elmer 403), using a flameless graphite furnace for aqueous Cd and Pb.
Culture tnediutn
In order to aid taxonomic identification, organisms were cultured in the laboratory at 15 OC and
under various light regimes. A modification of the
No. 10 medium of Chu (1942) was used. The
changes to this included the following: reduction of
pH to 3.5 by the addition of H 2 S 0 4 , with the inclusion of 3.0 mM 3,3 dimethylglutaric acid t o provide
buffering capacity; use of ammonia (1 mg 1-I NH3-
The acid springs comprising the Paint Pots are
located in Kootenay National Park, British Columbia along the Western slopes of the Rocky
Mountains ( 1 16" 08' W, 51° 10' N). A thorough
description of the location, geology and history of
these springs has already been given by Van Everdingen (1970), so only a brief summary is provided
here. The springs occupy a relatively small area
(c. 0.3 km2) east of the Vermilion River. They occur at an elevation of about 1450 m, lying within the
Englemann Spruce-Subalpine Fir Biogeoclimatic
zone (Krajina 1969).
Mineralized water which flows out of the springs
forms extensive deposits of iron oxide and hydroxides throughout the area, which are known as the
'Ochre Beds'. Vegetation which may become established thus becomes smothered by this continual
deposition of ochre. Dead trees have fallen into the
stream from along the banks, which themselves
become iron encrusted (Fig. 1). No solid mineral
substrata exist in the streams as the bottom consists
entirely of flaking iron crusts and ochreous silt.
Fig. 1. Main outflow stream of the Paint Pots downstream of
site IV. showing dead trees falling into the acid water.
T h e overall appearance of the springs was of a
nearly barren area with only the margins of one
pool (Figs. 2 , 3 ) colonized by macrophytic angiosperms (Typha sp.). Moist ochre beds not directly
submerged by acid waters were colonized by a few
scattered plants of a grass (not identified). N o obvious 'blooms' of algae were seen in the pools or on
the stream bottom. Sediments in these two environments did, however, have a distinctly green colour. Bright green cushions of bryophytes were visible in several places. During the time of the study,
fresh tracks of several large mammals (including elk
and deer) were found around the edges of the acid
pools.
Sites were chosen as far as possible t o coincide
with those examined previously (Fig. 3). Pools
from three active springs (sites I, 111, V: the 'Paint
Pots') overflow to form a small stream which runs
first southeast and then south to where it joins the
Vermilion, about 2.5 km downstream. The second
set of acid springs studied by Van Everdingen,
nearby at Ochre Hill, were all dried up during the
time of sampling. This included one spring (point
19 of Van Everdingen) previously thought t o flow
year round.
Fig. 2. First major Paint Pot (site I), showing marginal vegetation and otherwise barren littoral zone.
Y
$ ~ i c e a l ~ b i eforest
s
v
marshy ochre
IY
0sampling site
Fig. 3. Paint Pots study area, showing location of sampling sites.
Results
Chemistry
Physico-chemical characteristics of sites I
through VI are given in Table 1. T h e p H was very
low a t all sites a n d dissolved oxygen was below o r
near the detection limit at all sites. T h e three springpools (I, 111, V) were apparently the most extreme
with respect to these variables.
There is a clear change in the concentrations of
some metals in the water downstream (sites I-IV
and VI) from the upper.Paint Pot (Table 2). Levels
of Al, Fe, Zn, C d and P b decrease from the first
spring (I) downstream t o site IV. After receiving
additional acid water from the smallest spring (site
V) A1 increased tenfold, but F e a n d Z n decreased
slightly. Many other metals, particularly Na, K and
Ca, show little pattern. It is clear that F e is the most
abundant filtrable metal in the Paint Pots water, in
addition to its visually obvious abundance in the
particulate form as ochre.
Iron is also the most abundant metal in the sediments, comprising between 20 and 45% of the total
Table I. Physical and chemical variables at Paint Pots sites I-VI.
temperature (OC)
conductivity at 25 OC (ps cm ' )
PH
0, (mg 1 ' )
0, (% sat)
depth (cm)
width (m)
Van Everdingen site
description
* Not studied previously.
pool
Stream
pool
15.9
1205
4.0
<0.05
0
3.5
5.6
13
Stream
14.5
1440
3.1
<0.05
0
45
3 .O
12
pool
13.8
1275
3.4
0.22
2.5
6.0
0.5
15
stream
Table2. Metal composition of water (mg t ' )at Paint Pots sites I-VI. All values refer to water passed through a Whatman G F / C glass
fibre filter (approximately 2 p m pore size).
All sites: Cr,
< 0.006; C o & Ni, < 0.01; Cu, < 0.005.
Table 3. Metal composition (pg g-') of sediments (< 210 pm fraction) from sites I-VI
Table 4 . Floristic composition of benthic and planktonic associations of aquatic cryptogamic communities at sites I-VI. Relative
abundance on subjective of scale 1-5 (with the most abundant: see Holmes & Whitton 1977).
Species
Benthic
Chrysophyta
Ochromonas sp.
Bacillariophyta
Fragilaria construens (Ehr.) Grun. var. pumila Grun
Meridion circulare (Greg.) Ag.
Eunotia tenella (Grun.) CI.
Achnanthes n~inutissimaKiitz.
Caloneis bacillunt (Grun.) CI.
Navicula cf. N. exigua Greg.
N. radiosa K iitz.
Nirzschia cf. N. palea (Kiitz.) W. Sm.
Pinnularia microsrauron (Ehr.) CI.
Chlorophyta
Chlani.~~domonas
m o e ~ u s i Gerloff
i
C . perpusilla (Korsh.) Gerloff
Chlorella cf. C . prorothecoides Kriiger
Srichococcus bacillaris Nag.
Bryophyta
Cephalozia bicuspidara ( L . ) Dum.
* Dicranella hereromalla (Hedw.) Schimp.
* = only protonema
in field
Planktonic
weight (Table 3). As with the waters, A1 and Zn are
also prominent, but Ca is not as abundant as might
be expected from the relatively high levels in the
water. Although P b is several orders of magnitude
less abundant in the water than Ca, it is approximately the same in the sediments. The downstream
reduction of many aqueous metals was paralleled in
the sediments by Zn, Cd and Pb, but not by Fe or
Al.
'
Table 5. Metal composition ( f i g g ) of C~phaluziahicrtspiclora
from sites I V and V1.
1v
vI
Species composition
The predominant species of the springs (sites I,
111, V) were unicellular green algae, both in the
benthic and planktonic associations(Table4). Several diatom species were found (live) in the sediments of both lentic and lotic habitats, but none of
these were abundant.
Several algal taxa were widespread throughout
the Paint Pots area, but the leafy liverwort Cephalozia hicwpiduta was much more abundant than
those in the two lower stream sites (lV, VI). This
liverwort was found in bright or dark green colonies
on the ochreous silt all along the stream. The average leaf size was somewhat smaller than is normally
encountered for this species, but plants were otherwise of typical morphology. In contrast, the moss
Dic~raneflah e t m m a l l a was found only as protonema.
Metal composition of Cephalozia bicuspidaia
The metal composition of the predominant photosynthetic organism of stream sites IV and VI,
Cephalozia bicrrspidata, is given in Table 5. Between 20-30% of the dry weight of these (living)
plants consisted of Fe. Other cushions of Cephalozia were found to be entirely covered with a brittle
iron oxide crust 1-2 mrn thick and were presumably
nonliving. The massive accumulation of Fe is
shown by comparing the ratio of Fe and Zn in
water, sediments and Cephafozia bicuspidara (Ta-
ble 6). The sediments and bryophytes have accumulated F e a t concentrations far inexcess of that in the
water, much more than for Zn. Further, while the
Fe : Z n ratio in water is reasonably constant from
site t o site, this ratio varies considerably in the
sediments. A1 is also enriched in both the sediments
and C. biczrspidata much more than is Zn.
Discussion
The chemistry of these natural springs appears to
have changed little in the decade from 1969 to 1979
(Table 7); in view of the difficulties involved in
filtration, any differences appear minor. Besides
their low pH, the waters were characterized by
elevated levels of heavy metals, especially Fe and
Zn, and by the absence of dissolved oxygen near the
site of emergence from underground. The presence
of elevated levels of heavy metals is also a general
feature of acid mine drainages (Hargreaves et al.
1975), but in comparison with the reports in the
literature for sites in the pH range 3-4 (Roback &
Richardson 1969; Warner 1971; Hoen& Sizemore
1977; Rasmussen & Sand-Jensen 1979), Fe levels
were particularly high. Elsewhere in the literature
reports of aqueous Fe greater than 100 mg I-' appear to be restricted to pH values < pH 3.0 (Bennett
Table 6 . Comparison of the ratio of Fe:Zn concentrations in water, sediments and Cephalozia bic~uspidaro.
I
water
sediments
Cephalo=ta
II
111
1V
V
VI
Mean
Table 7. Comparison of selected aqueous metals (rng 1 ' ) in the
Paint Pots, measured in 1969 (Van Everdingen 1970) and 1979
(present study).
1969; Satake & Saijo 1974; Hargreaves et al. 1975).
T h e high levels of Fe presumably result from the
fact that all the metal present at the source occurs as
Fell due t o the anaerobic conditions. Although
only a few measurements of dissolved oxygen in
acid mine drainage have been reported in the literature (Roback & Richardson 1969; Hargreaves et al.
1975; Parsons 1977), it seems likely that these environments are less often anaerobic.
T h e photosynthetic cover of most of the Paint
Pots was sparse, but local areas of the sediments did
have a distinct green colouration. Unlike many acid
mine drainages (Lackey 1938; Hargreaves et al.
1975), there were no macroscopic colonies o r flocs
of algae. T h e total species for the six sites was only
18 ( o n the assumption that there are two angiosperms). T h e maximum number of cryptogams a t
one site was 12. It is difficult to relate these numbers
with other polluted sites, particularly when some
studies cover several seasons (e.g. Bennett 1969).
However, a comparison with a scattergram of loglo
Z n in water versus number of species for 424 (acid
a n d non-acid) sites shown by Whitton & Diaz
(1980) indicates that for the level of Z n present in
their waters, the Paint Pots lie about half-way between the species-poor and species-rich extremes.
As almost all the Zn-rich sites included by Whitton
a n d Diaz were due t o man's activities, it might be
expected that the Paint Pots would have a much
richer flora, since there has been a considerably
longer time for species t o invade. The continual and
heavy deposition of fine ferric hydroxides in sufficient quantities t o have been mined in the past (Van
Everdingen 1970) may be further inhibiting the successful colonization by more species.
Several of the species most widely recorded for
acid waters were not found at the Paint Pots, in
particular Euglena mutabilis, which is by far the
most widespread species in such environments
(Lackey 1938; Bennett 1969; W hitton & Diaz 198 1).
Whitton & Diaz found that the majority of acid
sites (pH G 3.0) lacking E. mutabilis have a hard
superficial crust with much iron oxide. Although
there is much iron oxide in the Paint Pots, the
majority is present as fine sediment ('ochre') rather
than a hard crust which might hinder the movement
of this alga. I n view of the fact that two species of
Chlamydomonas were the most abundant algae of
the Paint Pots, the absence of C. acidophila(Fott &
McCarthy 1964; Satake & Saijo 1974) requires explanation. Nine of the 14 algae are potentially motile, but the Chlamydomonas forms existed largely
in the palmelloid state when growing among the
sediments, and were only motile in the plankton.
Although Watson (1955) states that Cephalozia
bicuspidata always favours a n acid substratum,
there is only one other record for a n acid drainage
( p H 2.6 : Whitton & Diaz 1981). Lackey (1938)
noted the rarity of liverworts in streams receiving
acid mine drainage, while Antonovics et al. (1971)
also mention that liverworts are more rare on metal-contaminated soils than are mosses, although
Cephalozia spp. are the forms most commonly encountered. The presence of Dicranella heteromalla
a t the Paint Pots is much more typical of highly
acidic waters with pH values G4.0. D. heteromalla
is one of the most common colonizers of acid coal
spoils in Iowa (Carvey et al. 1977). Forms of Dicranella probably always referable to this species were
one of the eight most widespread organisms found
by Whitton & Diaz (1981) in such waters; none of
the other eight species were found at the Paint Pots.
T h e relatively sparse flora of the Paint Pots a n d
its marked floristic differences from acid mine
drainages all suggest that some factor or factors are
operating here which are less important in acid
mine drainages. Most photosynthetic microorganisms a t the Paint Pots must exist for much of the
time under almost or completely anaerobic conditions and tolerate very high levels of aqueous FeII.
It is suggested that these may be two of the key
factors here which differ from man-induced acid
waters and may help to explain the absence of at
least some of the otherwise widespread species in
acidic environments like Euglena mutabilis and
Chlamydomonas acidophila. The organisms must
also tolerate the physical effects of massive ochre
deposition, but this is a feature shared with many
mine drainages.
T h e very high concentration of iron associated
with Cephalozia bicuspidata probably results mostly from the deposition of ochre rather than accumulation in the tissues of the plant. Co-precipitation in
the sediments of zinc with iron appears t o be relatively low, though again probably responsible for
much of the zinc found in the Cephalozia digests
(Table 3). T h e two direct comparisons of sediment
and liverwort (Table 6) d o not suggest that accumulation in the plant is much more important than in
the sediments. The enrichment ratio, (plant any
surrounding deposit) : water, for zinc is much lower
than found in plants in a non-acid lead mining area
with similar levels of aqueous zinc (Whitton e f al.
1981). T h e ratio is however quite similar to that
found for the moss Drepanocladus fluitans in a
mine drainage at pH 2.6 with 1.0 mg 1 - I Z n (Whitton & Say 1975), being68 and 71 at the two Kootenay sites and 44 in the mine drainage. It seems that
the levels of zinc (and probably also many other
heavy metals) accumulated by plants under highly
acidic conditions are relatively low.
+
Acknowledgments
Part of the work was completed while J. D . W.
was financed by the Department of Environment
( D O E grant DGR/480/571; 'Aquatic bryophytes
for monitoring river water quality'). We are grateful
to: Prof. J. R. Stein(Univ. of British Columbia) for
providing field equipment and laboratory facilities
during 1979; D r R. E. DeWreede (Univ. B. C . ) for
generous assistance in the field; Prof. W. B. Schofield (Univ. B. C.) for aid in identification of Cephalozia; D r J . H. Belcher(Cu1ture Collection of Algae
& Protozoa, Cambridge) for help with Chlamydomonas taxonomy; J . W. Simon for aid with culturing; D. M. Richards for aid with metal analyses.
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