The impact of air pollution on the integrity of cell membranes and

Arch. Environ. Contam. Toxicol. 24, 455-460 (1993)
A R C H I V E S
OF
Environmental
Contamination
a n d Toxicology
© 1993 Springer-Verlag New York Inc.
The Impact of Air Pollution on the Integrity of Cell Membranes and Chlorophyll
in the Lichen Ramalina duriaei (De Not.) Bagl. Transplanted to Industrial Sites
in Israel
Jacob Garty 1, Yuval Karary, and Joseph Harel
Department of Botany and Institute for Nature Conservation Research, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv
69978, Israel
Abstract. The impact of air pollution on the integrity of cell
membranes and chlorophyll in the lichen Ramalina duriaei was
studied. The lichen was transplanted from a relatively unpolluted site in Israel to a highly polluted area for a period of 10
months. The seasonal variation of the percentages of Mg as
detected with the aid of scanning electron microscopy (SEM)
and energy dispersive X-ray analysis (EDX) on/in the cortical
cells of the lichen was compared with changes in the chlorophyll integrity as expressed by the ratio OD 435 nrrdOD 415
nm. The rate of damage of air pollution to cell membranes in
the lichen was compared with the increase of S as detected on
the surface of the lichen thalli retrieved from industrial sites.
The present study indicates that the electric conductivity parameter reflecting the integrity of lichen cell membranes was found
to express the cellular damage caused to lichen thalli transplanted to a steel smelter and to oil refineries. Symptoms of
damage to cell membranes are detectable in R. duriaei long
before any indication of damage becomes apparent in the photobiont chlorophyll. Magnesium seems to represent a significant leakage from intracellular sites of the thallus. The accumulation of sulfur on/in the cortical cells of R. duriaei indicates
that the biomonitoring sites at the Haifa Bay are contaminated
by SO 2.
During the past two decades several studies emphasized the
feasibility of lichens as effective biomonitors (Ferry etal. 1973;
Martin and Coughtrey 1982; Arndt et al. 1987; Nash and Wirth
1988; Galun and Ronen 1988). Lichens are very sensitive to
SO2, fluorides, ozone, nitrogen oxides, peroxyacetyl nitrate
(PAN) and heavy metals.
Topics studied extensively in the context of air pollution and
lichens include the rate of respiration (Baddelely et al. 1972),
photosynthesis (Showman 1972; Richardson and Puckett 1973;
Canaani et al. 1984), chlorophyll fluorescence (Kauppi 1980),
chlorophyll content (Henriksson and Pearson 1981), decrease
1To whom correspondence should be addressed.
of ATP (Kardish et al. 1987; Garty et al. 1988) and changes in
the levels of endogenous auxin and ethylene (Epstein et al.
1986). The bleaching of lichen thalli as a result of the degradation of chlorophyll is one of the most obvious indications of
damage by airborne pollutants (Nash 1971; Ronen and Galun
1984; Garty et al. 1985, 1988; Silberstein and Galun 1988).
Ronen and Galun (1984) extracted the photosynthetic pigments from the lichens by the immersion of the thalli in dimethylsulfoxide (DMSO). They suggested the ratio of optical density at wavelengths of 435 nm and 415 nm as a reliable
parameter for the estimation of chlorophyll degradation. The
advantages of DMSO as a solvent for the extraction of photosynthetic lichen pigments are that the extraction is simple, rapid
and complete, and the extract is easily stored in the cold without
degradation.
A simple test to check whether the plasma membrane enclosing lichen cell membranes enclosing lichen cells is normal is to
place a piece of excised lichen thallus in distilled deionized
water for two or three minutes (Simon 1974; Puckett et al.
1977). Pearson and Henriksson (1981) showed the effect of
SO2 on membrane leakage in three lichens. In Evernia prunastri, increased leakage occurred at all SO2 levels from 0.32 ppm
and above. The conductivity values obtained after the exposure
of this lichen to 0.32, 100 and 300 ppm SO 2 were found to be
10.04, 12.25, and 300 Ixmho/g/ml, respectively when immersed for 2 min in deionized distilled water. Similar findings
were reported by Pearson and Rodgers (1982), Alebic-Juretic
and Arko-Pijevac (1989), Rope and Pearson (1990), and Silberstein (1990). These studies were laboratory experiments or
investigations performed under field conditions in sites where
SO2 was the major contaminant of the air.
The major objectives of the current investigation were to
study environmental conditions during different seasons of the
year and to determine the integrity of chlorophyll as expressed
by the OD 435 nm/OD 415 nm ratio under these conditions.
The integrity of cell membranes as expressed by changes of the
electric conductivity in doubly distilled water of a sensitive
lichen in its native unpolluted habitat is used as the control.
An additional objective of the study was to determine
whether changes in the integrity of chlorophyll and of cellmembranes are comparable in the case of lichens transplanted
J. Garty et al.
456
A
HaZorea site, in September and December 1989 and February, April
and June 1990 as fresh material ("in situ" in Tables 1-3).
/
N
Extraction and Assessment of the Integrity of Chlorophyll
The chlorophyll of lichens sampled from the sites in Haifa Bay and
from the control site (re-suspended as well as in situ material), was
extracted overnight in the dark in 3 ml of dimethylsulfoxide (DMSOMerck Product, analytical grade). The ratio of chlorophyll a to phaeophytin a (OD 435 nm/OD 415 nm) was determined as previously
described (Ronen and Galun 1984) using a Varian spectrophotometer,
model 460.
I
5 km
.
2"
1
Assessment of Damage to Cell Membranes by
Measurement of Changes in the Electric Conductivity in
Doubly Distilled Water
4.
Batches of in situ lichen material, re-suspended thalli from the control
site, as well as transplanted thalli retrieved from the Haifa Bay sites
were transported to our laboratory at Tel Aviv University. They were
rinsed for several seconds in a doubly distilled water, kept in a laboratory for 24 h, and divided into samples of 1 g each. Lichen samples
were immersed in 100 ml doubly distilled water for 5 min. The electric
conductivity of the water was measured with an electric conductivity
meter (Radiometer Copenhagen, type CDM, 2e).
1,
Energy Dispersive X-ray Analysis (EDX) of the
Thallus Surface
Fig. 1. The study area: (1) HaZorea forest (control site); (2) the agricultural village, Kefar Bialik, Haifa Bay; (3) the steel smelter, Kiryat
Happlada, Haifa Bay; (4) the oil refineries, Haifa Bay
to polluted areas from different periods of time. Changes in the
integrity of chlorophyll and cell-membranes in lichens exposed
to contaminated sites against changes in the elemental composition of the surface of the thallus were also investigated.
Materials and Methods
The fruticose lichen Ramalina duriaei (De Not.) Bagl., which grows
on twigs of carob trees (Ceratonia siliqua L.), was collected throughout the study period from a site in the HaZorea Forest (site 1, Esdraelon
Valley, northeast Israel), deemed 'clean' in terms of air pollution
(Garty and Fuchs 1982; Garty et al. 1985). In September 1989, about
200 detached twigs covered by R. duriaei were transferred to three
different monitoring stations in the Haifa Bay area (Figure 1), a region
subject to the heaviest industrial pollution in Israel. One of the sites,
Kefar Bialik (site 2), is an agricultural village surrounded by several
industrial plants, including two fertilizer factories (Haifa Chemicals
Ltd. and "Deshanim"). Another site is near the steel smelter Kiryat
Happlada, in the vicinity of Kibbutz Kefar Massaryk, south of the city
of Akko (site 3). Lichens were transplanted also to the vicinity of
several oil refineries (site 4). Concurrently, some of the twigs carrying
lichens were re-transferred to the original carob trees for use as resuspended control specimens. Fresh thalli were picked in December
1989, February, April and June 1990, and compared with the material
transplanted to the Haifa Bay (which was retrieved simultaneously). In
addition, in situ lichens were collected directly from carob twigs at the
Lichen samples from Haifa Bay and the control site were rinsed carefully in doubly distilled water and then air-dried for 2 d. The thalli were
mounted on sample stubs, coated with carbon using a Polaron coating
unit E S100 and examined in a Jeol 840A Scanning Electron Microscope (SEM) operating at 25 kV. Analyses were performed directly in
the SEM, using the Link System 860. Elements were analyzed with a
ZAF-4 program. The voltage for the energy dispersive analysis was 25
kV. Results of EDX using the ZAF-4 program are given as percentages
of each of the 12 analyzed elements on the cortex of thalli from
different sites and are evaluated with Duncan's multiple range test. For
that purpose, ~/arcsin P/100 transformation was used first in order to
obtain the normal distribution. The percentages of Mg and S detected
on the lichen cortex are reported in this paper.
Results
The OD 435 nrrdOD 415 nm ratios of the samples from the
exposure sites are presented in Table l. In previous studies,
values of 1 . 4 5 - - - 0 . 0 3 (Ronen and Galun 1984) and
1.42 --+ 0.03 (Garty et al. 1985) were obtained from R. duriaei
in the unpolluted HaZorea forest site. In these studies the OD
435 nm/OD 415 nm ratio was found to be the lowest
(0.56 --- 0.03) in acidified solutions (Ronen and Galun 1984)
and 1.03 -+ 0.22 in R. duriaei transplanted to a polluted site in
Tel A v i v (Garry et al. 1985). Results obtained by the analysis
following the examination of the R. duriaei lichen material
indicate that the OD 435 nm/OD 415 nm ratio, expressing the
integrity of the chlorophyll in the photobiont partner, proved to
be the greatest in April (Table 1). A significant degradation of
the chlorophyll was observed in the lichen material exposed to
Integrity of Cell Membranes and Chlorophyll in Lichens
457
Table 1. Chlorophyll degradation expressed as OD 435 nrrgOD 415 nm ratio in the thalli ofRamalina duriaei collected at the study area. Values
are based on 10 replicates. Values in each vertical column followed by the same capital letter and values in each horizontal line followed by the same
small letter do not differ significantly at p = 0.05 by Duncan's multiple range test
Site number
1
Site
description
HaZorea Forest
(control site),
in situ
material
Sep. 1989
Dec. 1989
Feb. 1990
Apr. 1990
June 1990
2
3
4
HaZorea Forest
(control site),
re-suspended
material
The Agricultural
village Kefar
Bialik (Haifa Bay),
transplanted
material
Kefar Massaryk
near the steel
smelter (Haifa
Bay), transplanted
material
The Oil
Refineries
(Haifa Bay),
transplanted
material
-+ 1.45
0.05
BC
-+ 1.44
0.04a
BC
-+ 1.45
0.02a
-+ 1.45
0.05
B
--+1.42
0.03b
B
-+ 1.44
0.03a
-4-1.45
0.05
BC
-+ 1.41
0.03b
C
-+ 1.47
0.09a
+--1.45
0.05
A
-+ 1.42
0.03b
A
-+ 1.43
0.06a
-+ 1.45
0.05
B
-+ 1.41
0.03b
C
-+ 1.45
0.01a
B
B
B
A
B
-+ 1.52
0.02a
A
-+ 1.42
0.02a
C
+ 1.50
0.03a
A
-+ 1.43
0.01a
B
-+ 1.52
0.03a
A
--
-+ 1.46
0.09b
A
-+ 1.11
0.14b
B
-+ 1.52
0.02a
A
-+ 1.39
0.03a
C
Table 2. Electric conductivity of doubly distilled water measured five min after thalli of Ramalina duriaei collected at the study area have been
soaked in. Data are given in mS m -~ .* Values are based on 10 replicates. Values in each vertical column followed by the same capital letter and
values in each horizontal line followed by the same small letter do not differ significantly at p = 0.05 by Duncan's multiple range test
Site number
1
Site
description
HaZorea Forest
(control site),
in situ
material
Dec. 1989
Feb. 1989
Apr. 1990
June 1990
2
3
4
HaZorea Forest
(control site),
re-suspended
material
The Agricultural
village Kefar
Bialik (Haifa Bay),
transplanted
material
Kefar Massaryk
near the steel
smelter (Haifa
Bay), transplanted
material
The Oil
Refineries
(Haifa Bay),
transplanted
material
-+0.37
0.10c
-+0.31
0.12c
-+0.95
0.30c
-+0.96
0.12b
-+2.41
0.38a
B
B
A
B
B
-+0.07
0.00d
C
-+0.31
0.09c
-+0.14
0.04cd
C
-+0.31
0.04c
-+0.29
0.05c
B
-+0.99
0.22ab
-+0.47
0.12b
C
-+0.86
0.21b
-+ 1.00
0.45a
C
-+ 1.08
0.17a
B
B
A
B
C
+0.75
0.12c
A
-+0.79
0.15c
A
--
-+4.55
0.49a
A
-+3.00
0.24b
A
* milliSiemens/meter
the industrial sites at Haifa Bay (sites 3 and 4), which was
retrieved in June 1990.
The integrity of cell membranes in R. duriaei as expressed by
changes in the electric conductivity of water is shown in Table
2. The findings reveal that at all biomonitoring sites the lowest
electric conductivity values were obtained in the winter (February 1990) whereas a seasonal peak was recorded in June 1990.
The highest electric conductivity values were observed in the
lichens retrieved in June from the industrial sites (sites 3 and 4)
at Haifa Bay.
The elemental analysis of the thallial cortex of R. duriaei
samples retrieved from Haifa Bay revealed that the percentages
of magnesium increased gradually during the entire period of
the experiment (sites 2, 3 and 4, Table 3), whereas the control
thalli (site 1) were found to contain low Mg values on the
thallus surface during the entire study period.
The percentages of S detected on the thallus surface of the
control material were quite similar during the period September
1989 (0.22 -+ 16%)-June 1990 (0.20 -+ 0.08%), whereas the
accumulation of this element in the lichen exposed in the agricultural village increased gradually during the period September 1989-April 1990. A similar trend was observed at the two
other sites at the Haifa Bay: the percentages of S on the thallus
surface of the lichens retrieved from the steel smelter reached at
458
J. Garry et al.
Table 3. Percentages of magnesium detected on the cortex of Ramalina duriaei collected at the study area and analysed with the aid of SEM
combined with EDX. Values are based on analyses of 30 thalli. Values in each vertical column followed by the same capital letter and values in each
horizontal line followed by the same small letter do not differ at p = 0.05 by Duncan's multiple range test
Site number
1
HaZorea Forest
(control site),
Site
description
Sep. 1989
Dec. 1989
Feb. 1990
Apr. 1990
June 1990
material
HaZorea Forest
(control site),
re-suspended
material
-+0.08
0.06
A
-+0.08
0.05b
A
---0.07
0.04b
A
-0.10
0.06b
A
-+0.08
0.06c
A
-+0.08
0.06
AB
±0.11
0.05ab
A
---0.07
0.05b
B
-+0.10
0.05b
AB
±0.07
0.04c
B
in situ
the end of the experiment 0.41 --- 0.15%, whereas corresponding values of S as detected on the surface of the lichen thalli
retrieved from the oil refineries in June 1990 was 0.37 --- 0.14%.
Discussion
Our study indicates that symptoms of damage to cell membranes of either the lichen mycobiont or the photobiont partner,
or both, are detectable in R. duriaei transplanted to polluted
sites long before any indication of damage becomes apparent in
the photobiont chlorophyll. In the current experiments, the
degradation of chlorophyll occurred in thalli transplanted to the
steel smelter only towards the end of the investigation. On the
contrary, Wetmore (1988) stated that the algae of the thallus in
lichens are the first to be damaged in areas with air pollution
and that the first indication of damage is discoloring and death
of algae, quickly leading to the death of the entire lichen.
A pollution-resistant lichen species, Parmelia sulcata, was
reported by von Arb (1987) to be the only one encountered in
the most polluted parts of the city of Biel, Switzerland. The
chlorophyll content was found to be the highest in lichen at four
central and very polluted parts of the city whereas in the periphery, three to five times lower. That and similar reports (von Arb
and Brunold 1990; von Arb et al. 1990) may be compared with
reports of the relatively tolerant lichen Xanthoria parientina
(Silberstein and Galun 1988; Silberstein 1990), which like
P. Sulcata is well adapted to polluted areas. As for R. duriaei,
the decrease in the OD 435 nm/OD 415 nm ratio upon transplantation to polluted sites indicates that the lichen is rather
sensitive to pollution and is therefore endandgered throughout
the whole Haifa Bay region. That conclusion is supported by
our earlier report of a significantly low OD 435 nm/OD 415 nm
ratio in indigenous R. duriaei thalli collected on a certain peak
of Mount Carmel, Israel (Garry et al. 1985). Our findings
2
3
4
The Agricultural
village Kefar
Bialik (Haifa Bay),
transplanted
material
Kefar Massaryk
near the steel
smelter (Haifa
Bay), transplanted
material
The Oil
Refineries
(Haifa Bay),
transplanted
material
-+0.08
0.06
B
±0.11
0.07ab
B
-0.15
0.08a
A
-4-0.18
0.1 la
A
--
-+0.08
0.06
C
-+0.10
0.07a
BC
-+0.15
0.08a
B
-0.14
0.09b
B
---0.23
0.15a
A
-+0.08
0.06
C
-+0.14
0.08a
AB
±0.14
0.08a
AB
±0.12
0.07b
B
±0.16
0.07b
A
regarding the use of R. duriaei as a bioindicator of air pollution
indicate that lichen thalli taken from a relatively clean site
undergo drastic changes upon transferring to polluted sites,
mainly because of the impact of pollution and not because of
the transplantation itself.
As for the changes in cell membrane permeability as reflected by the increase of electrolyte leakage, the electric conductivity parameter was found to express successfully the cellular damage caused to R. duriaei thalli transplanted to the steel
smelter and to the oil refineries at Haifa Bay.
Magnesium seems to represent a significant leakage from
intracellular sites of the thallus, indicated by a detectable accumulation on the lichen surface. Because the control thalli exhibited a different pattern of Mg accumulation under similar climatic conditions prevailing in the whole study area, we suggest
that the accumulation of that element on/in the cortical cells is
connected with ion leakage from internal parts of the thallus,
followed by deposition on the surface cells, as detected by the
SEM + EDX. Such leakages appear to result from environmental stress caused by the contaminated air prevailing in the
Haifa Bay area.
Magnesium, which accumulated on/in the cortical cells of
R. duriaei may have been derived from chlorophyll degradation. Boonpragob and Nash (1990a) found that during summer
periods at a polluted site in Los Angeles, chlorophyll and net
photosynthesis declined substantially in Ramalina menziessi
and that the percentage of phaeophytins increased in proportion. Leachable Mg, Ca, P, Na and K were found to increase in
this lichen during the summer (Boonpragob and Nash 1990b).
The authors stated that at least a part of the elevated rate of
leachable Mg in R. menziessi exposed to polluted conditions
derived from the degradation of the chlorophyll in the algal
cells of this lichen.
Lichens in their natural environment may be subjected to
repeated cycles of drying and wetting. Loss of a proportion of
Integrity of Cell Membranes and Chlorophyll in Lichens
their solutes each time they are wetted could have an important
cumulative effect (Simon 1974). Such cycles can occur quite
often in the Mediterranean climate even in winter time.
Buck and Brown (1979) showed that desiccation caused a
significant loss of intracellular K and Mg in some lichen species, and that the loss may be related to water available in the
natural habitat. These findings may explain the gradual increase
of Mg on the thallus surface especially in the lichens transplanted to Haifa Bay and retrieved in June 1990.
Essential ions were reported to be leached from lichens cells
upon exposure to chemical contaminants, e.g., SO2 and heavy
metals, under laboratory conditions (Puckett 1976; Puckett et
al. 1977; Nieboer et al. 1979; Goyal and Seaward 1982; Brown
and Beckett 1983; Beckett and Brown 1984; Silberstein 1990;
Garty and Delarea 1991), or in field studies (Fuchs and Garty
1983; Garty et al. 1985; Alebic-Juretic and Arko-Pijevac 1989;
Silberstein 1990; Boonpragob and Nash 1990b).
As for the accumulation of S on/in the cortical cells of
R. duriaei, the results of our investigation indicate that the
biomonitoring sites at Haifa Bay are contaminated by SO2.
High concentration of SO2 in the air in the surroundings of
lichens was previously proved to cause elevated concentrations
of S in lichens (Gilbert 1969; Hawksworth 1973; LeBlanc and
Rao 1973; Pyatt 1973; LeBlanc et al. 1974; Takala et al. 1985;
Garty et al. 1988). High SO2 concentrations were reported to
cause damage to agricultural plants in Haifa Bay area (Chaim et
al. 1973; Naveh et al. 1979). High S concentrations, detected
in R. duriaei thalli retrieved from the Haifa Bay area, reflect the
contamination of the air by SO2 emitted by heavy industrial
plants. That contaminant seems to be connected with the membranal damage in transplanted lichen thalli and the resultant
increase of electric conductivity; high values occurred especially in the lichen material retrieved from the steel smelter and
the oil refineries in,June 1990. Recently, it was reported that the
margins of the Haifa Bay area have been exposed to acid rain
with a pH range of 4.4 4.7 and high concentrations of SO42(Shamay et al. 1990). Because no regular instrumental monitoring of air pollutants is currently conducted in the Haifa Bay
area, it is recommended that a program be established to monitor contaminants and the integrity of chlorophyll and cell membranes in lichens transplanted to industrial sites. This information would document the relative significance of aerial
distribution, and the fallout, of industrial pollutants.
References
Alebic-Juretic A, Arko-Pijevac M (1989) Air pollution damage to cell
membranes in lichens-results to simple biological test applied in
Rijeka, Yugoslavia. Water Air Soil Pollut 47:25-33
Arndt U, Nobel W, Schweizer B (1987) Bioindikatoren. Ulrner, Stuttgart
Baddeley MS, Ferry BW, Finegan EJ (1972) The effects of sulphur
dioxide on lichen respiration. Lichenologist 5:284--291
Beckett RP, Brown DH (1984) The relationship between cadmium
uptake and heavy metal tolerance in the lichen genus Peltigera.
New Phytol 97:301-311
Boonpragob K, Nash III TH (1990a) Physiological responses of the
lichen Ramalina menziessi Tayl. to the Los Angeles urban environment. Environ Exp Bot 31:229-238
,
(1990b) Seasonal variation of elemental status in the
lichen Ramalina menziesii Tayl. from two sites in southern California: evidence for dry depostion accumulation. Environ Exp Bot
30:415-428
459
Brown DH, Beckett RP (1983) Differential sensitivity of lichens to
heavy metals. Ann Bot 52:51-57
Buck GW, Brown DH (1979) The effect of desiccation on cation
location in lichens. Ann Bot 44:265-277
Canaani O, Ronen R, Garty J, Cahen D, Malkin S, Galun M (1984)
Photoacoustic study of the green alga Trebouxia in the lichen
Ramalina duriaei in vivo. Photosynthesis Res. 5:297-306
Chaim S, Naveh Z, Donagi A (1973) The effect of phytotoxic concentrations of air pollutants on sensitive plants in the Haifa Bay. In:
Proceedings of the 4th Scientific Conference of the Israel Ecological Society, Tel Aviv, pp 101-125
Epstein E, Sagee O, Cohen JD, Garty J (1986) Endogenous auxin and
ethylene in the lichen Ramalina duriaei. Plant Physiol 82:11221125
Ferry BS, Baddeley MS, Hawksworth DL (eds) (1973) Air pollution
and lichens. Athlone Press, London
Fuchs C, Garry J (1983) Elemental content in the lichen Ramalina
duriaei (De Not.) Jatta at air quality biomonitoring stations. Environ Exp Bot 23:29--43
Galun M, Ronen R (1988) Interaction of lichens and pollutants. In:
M. Galun (ed) Handbook of lichenology, Vol Ili. CRC Press Inc,
Boca Raton, FL, pp 55-72
Garty J, Fuchs C (1982) Heavy metals in the lichen Ramalina duriaei
transplanted in biomonitoring stations. Water Air Soil Pollut
17:175-183
Garty J, Ronen R, Galun M (1985) Correlation between chlorophyll
degradation and the amount of some elements in the lichen Ramalina duriaei (De Not.) Jatta. Environ Exp Bot 25:67-67
Garty J, Kardish N, Hagemeyer J, Ronen R (1988) Correlations between the concentration of adenosine tri-phosphate, chlorophyll
degradation and the amounts of airborne heavy metals and sulphur
in a transplanted lichen. Arch Environ Contam Toxicol 17:601611
Garty J, Delarea J (1991) Localization of iron and other elements in the
lichen Nephroma arcticum (L.) Torss. Environ Exp Bot 31:367375
Gilbert OL (1969) The effect of SO2 on lichens and bryophytes around
Newcastle upon Tyne. In: Air pollution, Proceedings of the first
European congress on the influence of air pollution on plants and
animals, Wageningen 1968. Centre for Agricultural Publishing
and Documentation, Wageningen, pp 223-235
Goyal R, Seaward MRD (1982) Metal uptake in terricolous lichens.
III. Translocation in the thallus of Peltigera canina. New Phytol
90:85-98
Hawksworth DL (1973) Mapping studies. In: Ferry BW, Baddeley
MS, Hawksworth DL (eds) Air pollution and lichens. Athlone
Press, London, pp 38-76
Henriksson E, Pearson LC (1981) Nitrogen fixation rate and chlorophyll content of the lichen Peltigera canina exposed to sulfur
dioxide. Am J Bot 68:680-684
Kardish N, Ronen R, Bubrick P, Garty J (1987) The influence of air
pollution on the concentration of ATP and on chlorophyll degradation in the lichen Ramalina duriaei. New Phytol 106:697-706
Kauppi M (1980) Fluorescence microscopy and microfluorometry for
the examination of pollution damage in lichens. Ann Bot Fennici
17:163-173
LeBlanc F, Robitaille G, Rao DN (1974) Biological responses of
lichens and bryophytes to environmental pollution in the Murdochville copper mine area, Quebec. J Hattori Bot Lab 38:405433
Martin MH, Coughtrey PJ (1982) Biological monitoring of heavy
metal pollution. Applied Science Publishers, London
Nash III TH (1971) Lichen sensitivity to hydrogen fluoride. Bull Torrey Bot Club 98:103-106
Nash III TH, Wirth V (eds) (1988) Lichens, bryophytes and air quality.
Cramer, Berlin and Stuttgart
Naveh Z, Steinberger EH, Chaim S (1979) The use of bio-indicators
for monitoring of air pollution by fluor, ozone and sulphur diox-
460
ide. In: Cairns J Jr, Patil GP, Waters WE (eds) Environmental
biomonitoring, assessment, prediction and management----certain
case studies and related quantitative issues. International Co-operative Publishing House, Burtonsville, MD, pp 21-47
Nieboer E, Richardson DHS, Lavoie P, Padovan D (1979) The role of
metal-ion binding in modifying the toxic effects of sulphur dioxide
on the lichen Umbilicaria muhlenbergii. I. Potassium efflux studies. New Phytol 82:621-632
Pearson LC, Henriksson E (198 l) Air pollution damage to cell membranes in lichens. II. Laboratory experiments. Bryologist 84:515520
Pearson LC, Rodgers GA (1982) Air pollution damage to cell membranes in lichens. III. Field experiments. Phyton 22:329-337
Puckett KJ, (1976) The effect of heavy metals on some aspects of
lichen physiology. Can J Bot 54:2695-2703
Puckett KJ, Tomassini FD, Nieboer E, Richardson DHS (1977) Potassium efflux of lichen thalli following exposure to aqueous sulphur
dioxide. New Phyto179:135-145
Pyatt FB (1973) Plant sulphur content as air pollution gauge in the
vicinity of a steelworks. Environ Pollut 5:103-115
Richardson DHS, Puckett KJ (1974) Sulphur dioxide and photosynthesis in lichens. In: Ferry BW, Baddeley MS, Hawksworth DL (eds)
Air pollution and lichens. Athlone Press, London, pp 283-298
Ronen R, Galun M (1984) Pigment extraction from lichens with dimethyl/sulfoxide (DMSO) and estimation of chlorophyll degradation. Environ Exp Bot 24:239-245
Rope SK, Pearson LC (1990) Lichens as air pollution biomonitors in a
semiarid environment in Idaho. Bryologist 93:50-61
Shamay Y, Singer A, Ganor E (1990) Acid rain on the Carmel. In:
Abstracts of the 21st annual conference of the Israel Society for
Ecology and Environmental Quality Sciences, Beer Sheva, Israel,
ISEEQS Publications, Jerusalem, p. H-2
Showman RE (1972) Residual effects of sulfur dioxide on the net
J. Garty et al.
photosynthetic respiratory rates of lichen thalli and cultured symbionts. Bryologist 75:335-341
Silberstein L (1990) Evaluation of metabolic processes and endogenous protective compounds as defense mechanisms in an air pollution resistant lichen, PhD thesis (in Hebrew), Tel Aviv University,
Israel.
- - ,
Galun M (1988) Spectrometric estimation of chlorophyll in
lichens containing anthraquinones in relation to air pollution assessments. Environ Exp Bot 28:145-150
Simon EW (1974) Phospholipids and plant membrane permeability.
New Phytol 73:377-420
Takala K, Olkkonen H, Ikonen J, J~i~iskel~iinen J, Puumalainen P,
(1985) Total sulphur contents of epiphytic and terricolous lichens
in Finland. Ann Bot Fennici 22:91-100
Von Arb C (1987) Photosynthesis and chlorophyll content of the lichen
Parmelia sulcata Taylor from locations with different levels of air
pollution. In: Peveling E (ed) Progress and problems in lichenology in the eighties, Bibliotheca Lichenologica 25. Cramer, Berlin
and Stuttgart, pp 343-345
- - ,
Brunold C (1990) Lichen physiology and air pollution I:
Physiological responses of in situ Parmelia sulcata among air
pollution zones within Biel, Switzerland. Can J Bot 68:35-42
- - ,
Mueller C, Ammann K, Brunold D (1990) Lichen physiology
and air pollution. II. Statistical analysis of the correlation between
SO2,NO3,NO and 03, and chlorophyll content, net photosynthesis, sulphate uptake and protein synthesis of Parmelia sulcata
Taylor. New Phytol 115:431-437
Wetmore CM (1988) Lichens and air quality in Indiana Dunes National
Lakeshore. Mycotaxon 33:25-39
Manuscript received August 1, 1992 and in revised form December 1,
1992.