ENVIRONMENTAL
POLLUTION
Environmental Pollution 104 (1999) 157±167
Longitudinal patterns of stream chemistry in a catchment with
forest dieback, Czech Republic
M. Havel a, N.E. Peters b,*, J. Cerny a
a
Czech Geological Survey, KlaÂrov 3/131, Praha 1, Czech Republic
US Geologlical Survey, 3039, Amwiler Road, Suite 130, Atlanta, GA 30360-2824, USA
b
Received 17 December 1997; accepted 23 February 1998
Abstract
Longitudinal streamwater sampling in a 210-ha forested catchment (Jezeri), Czech Republic, was conducted approximately
quarterly from August 1992 through August 1994. The catchment has been severely impacted by atmospheric deposition of pollutants and subsequent landscape manipulation for reforestation. The impact and landscape manipulations decrease with decreasing
elevation. The concentration patterns re¯ect processes and dynamics that are not apparent from long-term monitoring at the basin
outlet. Streamwater concentrations of many solutes are highly correlated with elevation, vegetation cover and landscape history.
2ÿ
Concentrations of sulphate (SO2ÿ
4 ), the dominant anion, increased downstream. Low SO4 concentrations at the highest elevations
are attributed to a decrease in dry S deposition due to the loss of the forest canopy from Norway spruce dieback and subsequent
logging. Furthermore, liming and higher moisture content and water movement through the soils in the headwaters increases S
ÿ
mobility, resulting in lower SO2ÿ
4 concentrations at higher elevations. In contrast, highest nitrate (NO3 ) concentrations (300 meq
ÿ1
ÿ1
liter ) occurred at the highest elevations, decreased downstream to 80 meq liter at the outlet, and the rate of change in concentration was the most pronounced in the headwaters. The NOÿ
3 pattern is attributed to increased nitri®cation of the forest ¯oor
due to landscape excavation for drainage and reforestation, and liming (dolomitic lime). The N demand by 10±25-year-old reforested vegetation at mid elevations (705±800 m above sea level) is much greater than in the very young regrowth and open areas at
the highest elevations, causing concentrations to decrease through this zone. Streamwater NOÿ
3 concentrations also vary seasonally
ÿ1
due to vegetation demand during the growing season; but high NOÿ
3 concentrations (>50 meq liter ) persist at all sites, indicating
N saturation. High streamwater calcium (Ca2+) and magnesium (Mg2+) concentrations and low to moderate alkalinity (ALK) in
the limed, deforested and reforested areas also occur, particularly during low runo€ periods. ALK and hydrogen ion (H+), ¯uoride
(Fÿ) and dissolved aluminum (AlDIS) concentrations are highly correlated, particularly H+ and AlDIS. The low streamwater ALK
(in 90% of the samples ALK is less than 50 meq literÿ1), moderately low pH (in 45% of the samples pH is less than 5.6) and the
correlation with AlDIS suggests that the acid-base status is controlled by inorganic Al and organic complexes of Al and F. Published
by Elsevier Science Ltd.
Keywords: Norway spruce; Acidi®cation; Nitrogen; Sulfur; Biogeochemistry
1. Introduction
Acidic atmospheric deposition has impacted aquatic
ecosystems throughout the world. Since the mid 1970s,
much has been learned about biogeochemical processes
a€ected by atmospheric pollutants, particularly in sensitive areas where natural catchment alkalinity (ALK)
generation is insucient to bu€er acid inputs. Emissions
from fossil-fuel combustion have caused some of the
highest measured loads of atmospheric pollutants to
* Corresponding author. Tel.: +1-770-903-9145; fax: +1-770-9039199; e-mail: [email protected].
0269-7491/99/$Ðsee front matter Published by Elsevier Science Ltd.
PII: S0269 -7 491(98)00046 -3
the `Black Triangle' region of the northern part of the
Czech Republic and adjacent areas in southeastern
Germany and southwestern Poland (Moldan and
Schnoor, 1992). Few publications have discussed
detailed characteristics of streamwater chemistry in the
region or the processes that control streamwater hydrochemical variations. In this paper, we evaluate the
spatial dependence of streamwater chemistry on elevation, vegetation type and historical landscape manipulations in a small (210-ha) forested catchment in northern
Bohemia, Czech Republic. The catchment has been
severely impacted by high atmospheric deposition of
pollutants from fossil-fuel combustion.
158
M. Havel et al. / Environmental Pollution 104 (1999) 157±167
1.1. Background
The Krusne hory Mountains (Ore Mountains or
Erzgebirge) are in northwestern Bohemia along the
German border. The underlying bedrock consists of
Proterozoic metamorphic rocks and granites. The soils
are derived from residuum and include Cambisols
(50%), Spodosols (30%), Gleysols (5%), and Histosols
(5%), developed on ¯at plateaus in areas in¯uenced by
groundwater (PlõÂva and ZlaÂbek, 1986).
Brown coal deposits and clays comprise the lithology
of the adjacent basin at the southeastern base of the
Krusne hory Mountains. Industrialization began in
the region in the mid-to-late 1800s and coal from the
basin became the main energy source for former Czechoslovakia. After World War II, coal mining increased
rapidly; surface mining of brown coal increased from 13
to 72 Mt from 1946 to 1986. The sulfur (S)-rich coal
(1 to 15% S) is combusted locally in several power
plants (Moldan and Schnoor, 1992); these power plants
were without abatement technologies prior to 1994.
The combustion produced extremely high SO2 concentrations in ambient air (average SO2 for the 1980s
was >100 mg m3).
The biogeochemistry of this environment has been
a€ected by the high atmospheric pollutant deposition
and, subsequently, by landscape manipulations associated with remediation. As early as the 1960s, mature
(>60 years old) Norway spruce (Picea abies) were classi®ed as having been a€ected by air pollution by local
foresters, and a special forest management scheme was
adopted. 50% of the coniferous vegetation died from
1972 to 1989 (Ardo et al., 1997). Marked acceleration
of the forest dieback occurred in the mid-to-late 1970s,
and 25,000±40,000 ha of the dead forest were clearcut
(Kubelka et al., 1992). Forest dieback was most pronounced above 750 m, where most mature Norway
spruce were harvested as the spruce died. Remediation
included excavation of ditches for land drainage, partial
removal of the top soil with bulldozers, liming, fertilizing, and reforestation. The remediation process was
conducted on a large scale and, consequently, produced
large clearings which were generally unfavorable for
forest regeneration (Jirgle, 1984, 1988; Sach, 1990).
A geochemical mass balance of a small catchment
(X-14), adjacent to the small catchment reported herein
(X-16), was conducted by Paces (1985) who analyzed
the H+ budget. Paces (1985) demonstrated that acidic
inputs were dominated by dry deposition of SO2, which
contributed ten times more than wet deposition (554 mol
S haÿ1 yearÿ1 and 46 mol H haÿ1 yearÿ1). He reported
that the main mechanism for acid neutralization at
X-14 was the hydrolysis of bedrock and depletion
of exchangeable cations in soils. The acid neutralization was four times higher than that of a control catchment in a more pristine part of the Czech Republic.
Consequently, the base-cation exchange pool, which is
crucial for the survival of the forest, has been depleted
due to the severe acid deposition. Since 1978, major
constituent concentrations of forested catchment
streamwater have decreased and pH has increased
(Cerny, 1995). Streamwater sulfate (SO2ÿ
4 ) concentrations decreased, on average, by 35% from 1600 meq
literÿ1 in 1978 to 1100 meq literÿ1 in 1994. Streamwater
nitrate (NOÿ
3 ) concentrations decreased, on average, by
60% from 219 meq literÿ1 in 1980 to 87 meq literÿ1 in
1994 (Cerny, 1995). Factors thought to be responsible
for these changes are decreasing dry deposition due to
deforestation and an increasing nutrient requirement
for forest regrowth (Cerny, 1995).
2. Study site
The Jezeri catchment (X-16) is on the southeastern
slope of the Krusne hory Mountains, 2 km from the
coal basin (Fig. 1), and elevations range from 482 to 915
(m above sea level) X-16 is composed of two subcatchments, X-16A and X-16B, having areas of 210 and 50
ha, respectively. The higher elevations of X-16A (>705
m) were originally covered by a mature spruce forest,
which died in the mid-to-late 1970s; since then this area
has been clearcut, drained, reforested and limed. The
Fig. 1. Map of the Jezeri catchments, X-14, X-16, X-16A and X-16B
and longitudinal sampling sites within X-16A.
M. Havel et al. / Environmental Pollution 104 (1999) 157±167
landscape is relatively ¯at in the headwaters (0.15 m
mÿ1), but is dissected by many drainage ditches, and
mounds and furrows from the removal of top soil.
Catchment X-16B drains the eastern slope of the X-16
catchment and is covered with mature beech (Fagus
silvatica, 100±140-years-old). The con¯uence of X-16B
with X-16A is 45 m upstream of the X-16 outlet. Longitudinal sampling was conducted on X-16A, the mainstem tributary of X-16, which includes the headwater
area. The lower elevations (482±705 m) of X-16A
consists of steep slopes (25±55 ) and the stream
gradient is 0.3 m mÿ1. The catchment is underlain by
coarse-grained, micaceous orthogneiss and porphyric
muscovite±biotite metagranite, which have identical
mineralogical and chemical composition (Patrik, 1988).
In 1994, the vegetation cover of X-16A consisted of:
20% mature beech, contained exclusively in the lower
elevations below 705 m.a.s.l.; 68% young trees
(10±25 years old) from reforestation including birch
(Betula pubescens , B. verrucosa), mountain ash (Sorbus
aucuparia), European larch (Larix decidua) and spruce
(Picea pungens, P. abies), which is located above 705
m.a.s.l. and grades into the headwaters; and 12%
remnant mature spruce (P. abies), in pockets above the
beech forest to 850 m.a.s.l.
To facilitate future discussions, X-16A has been divided into three vegetation-cover zones, which also re¯ect
landscape history (Fig. 1): (1) a beech zone (105 ha),
present at lower elevations from 482 to 705 m.a.s.l., and
containing mature beech and streamwater sampling
sites 1±13; (2) a transition zone (99 ha), present at
intermediate elevations from 705 to 815 m.a.s.l., which
has been a€ected by spruce dieback and contains
regrowing vegetation, including some beech, some
remnant mature spruce stands, but a somewhat older
and better established reforested mixture of young
(<25 years old) birch, mountain ash and spruce than at
higher elevations; it also contains streamwater sampling
sites 14±22, and a small (2-ha) pond at 790 m.a.s.l.
between sites 21 and 20 (Fig. 1); and (3) a deforested
zone (6 ha), present at the highest elevations from 815 to
915 m.a.s.l., which had the highest impact (the worst
forest damage) from acidic atmospheric deposition and
contains some remnant mature spruce stands, the
reforested mixture of very young (<10 years old) trees
and grassland, and streamwater sampling sites 23±27.
3. Materials and methods
Streamwater was sampled approximately once each
quarter, resulting in seven collections during 2 water
years (WY, November through October) of 1993 and
1994. The sampling was conducted in November 1992
(XI/92), March 1993 (III/93), May 1993 (V/93), August
1993 (VIII/93), January 1994 (1/94), May 1994 (V/94),
159
and August 1994 (VIII/94). During each sampling
period, 27 sites, spaced 100 m apart, were sampled from
the basin outlet at site 1 (X16-A, a long-term monitoring site), elevation 482 m.a.s.l. to the headwaters at site
27, elevation 880 m.a.s.l. (Fig. 1). At each site, grab
samples were collected from the centroid of ¯ow in a
250-ml polyethylene bottle, which was pre-rinsed with
streamwater. For each sampling period, all 27 samples
were collected in 1 day starting at the outlet (site 1).
Streamwater samples were analyzed by the Czech
Geological Survey laboratories. On raw samples, pH
was determined using a radiometer GK 2401-C combined glass electrode. Acid neutralizing capacity (ALK)
was determined by titration with 0.1 M HCl using Gran
plot analysis (Gran, 1952) with a radiometer titration
system (TTT-85, ABU-80 autoburette and SAC-80);
and speci®c conductivity (KSC) was determined using
a Radelkis OK-102/1 conductivity meter. In addition, a
sample aliquot was ®ltered through a 0.45 mm Sartorius
SM-11306-47-N polycarbonate ®lter and concentrations
2ÿ
ÿ
of the anions, NOÿ
3 , SO4 , and chloride (Cl ), were
determined using a Shimadzu LC-6A ion exchange
chromatograph. Total ¯uoride (Fÿ) concentrations were
determined using a Crytur 09-27 ion selective electrode
after adjusting the ionic strength. Ammonium (NH+
4 )
concentrations were determined by spectrophotometry
using indophenol blue colorimetry (KobrovaÂ, 1983).
Another ®ltered sample aliquot was acidi®ed with
Ultrex HNO3 to pH<2 and used for determination of
cations and dissolved silica (H4SiO4). Concentrations
of calcium (Ca2+), magnesium (Mg2+), sodium (Na+),
potassium (K+), total dissolved aluminum (AlDIS),
and H4SiO4 were determined using a Perkin-Elmer
Plasma II inductively coupled proton-emission spectrophotometer (ICP).
Streamwater stage has been monitored continuously
since 1982 using a water-level recorder placed 45 m
downstream of the con¯uence of X-16A and X-16B at a
V-notch weir on the X-16 outlet (50 330 N, 13 300 E).
Average daily stage is converted to stream¯ow using a
rating curve developed from routine discharge measurements and stage at the outlet. During the last two
longitudinal sampling periods (V/94, VIII/94), stream¯ow was also measured at several of the sampling sites.
Daily precipitation amount was monitored nearby at
Vysoka Pec station (390 m.a.s.l.), situated at the foothills of the Krusne hory Mountains, approximately
2.5 km southwest from the outlet of the X-16 catchment.
4. Results
4.1. Hydrology
Average annual precipitation from 1978±96 at the
precipitation monitoring station, Vysoka Pec, was
160
M. Havel et al. / Environmental Pollution 104 (1999) 157±167
669 mm. At Vysoka Pec, the highest precipitation
occurs in summer (June±August averages 70 mm) and
winter (November±January averages 60 mm). The lowest precipitation occurs during February and October
(40 mm). Precipitation and atmospheric deposition
vary with elevation at X-16A; the average precipitation quantity to the entire catchment is 1.3 times higher
(870 mm) than that at Vysoka Pec (Havel et al., 1996).
From 1982 to 1994, average runo€ from X16 was
326 mm yearÿ1 (0.9 mm dayÿ1) and annual water yield
was 39%. Runo€ at X-16 is typically low during late
summer and early fall from August through November.
Maximum runo€ typically occurs during snowmelt in
March and April and during some summer storms
(Cerny and Havel, 1995). The main hydrologic event,
which accounts for 30% of the annual runo€, is
snowmelt, which begins in March or April and lasts
for about 1 month. Jezeri is typically snow-covered for
90±120 days (BoÈer and Vesecky, 1975).
Daily runo€ at X-16 during each of the seven sampling periods spans the range of daily runo€ from 1982
through 1994 (Fig. 2). Lowest runo€ occurred during
the August sampling period in each year (Fig. 3) with
0.1 and 0.2 mm dayÿ1 for 1993 and 1994, respectively.
Despite high rainfall (42.3 mm) during the week prior
to sampling in VIII/94, runo€ at the outlet did not
increase substantially. Runo€ during the May sampling
was higher than during August and was 0.4 and 0.7 mm
dayÿ1 for 1993 and 1994, respectively. Also, each May
sampling was preceded by several days of moderate
rainfall, totaling 18.6 and 35.0 mm for the previous
week in 1993 and 1994, respectively.
The stream at each sampling site was perennial at the
time of sampling. During the low and extremely low
¯ow sampling periods in V/94 and VIII/94, respectively, instantaneous discharge was measured at several
Fig. 2. Flow duration curve of daily runo€ from water years 1982
through 1994 and for the longitudinal streamwater sampling periods
(month/year) at Jezeri catchment X-16.
sampling sites in the catchment. Runo€ was consistent
among sites for each sampling period. For these measurements, runo€ ( i.e. ¯ow per unit area) was highest at
the highest elevation. For example, during the V/94
sampling period, runo€ increased from 0.5 to 1.5 mm
dayÿ1 for sites 1 and 23, respectively, and during the
VIII/94 sampling period, runo€ increased from 0.2 to
0.7 mm dayÿ1, respectively.
4.2. Streamwater chemistry
An overview of the general chemical composition of
the streamwater in X-16A is presented ®rst and is
followed by a summary of the spatial and temporal
patterns of constituent concentrations. The correlation
between concentration and elevation for each sampling
period is presented in Table 1. The relation between
concentration and elevation for each sampling period is
shown in Figs. 4±6 for most of the major constituents,
i.e. for cations (Ca2+, Mg2+, Na+, K+), anions (Fÿ,
2ÿ
Clÿ, NOÿ
3 , SO4 ) and weathering/acidi®cation components (H4SiO4, H+, AlDIS, ALK), respectively.
4.2.1. General characteristics
Streamwater at the outlet of the Jezeri catchment is
and Ca2+ (Cerny, 1995). Sulfate
dominated by SO2ÿ
4
varied markedly among sites and sampling periods
ranged from 650 to 1140 meq literÿ1 with an average of
84% of the total strong acid anion (SAA) equivalents at
the catchment outlet. For the remaining SAA, average
contribution to total cation equivalents was 10% for
ÿ
ÿ
2+
varied markNOÿ
3 , 5% for Cl , and 1% for F . Ca
edly among sites and sampling periods ranged from 410
to 950 meq literÿ1 with an average of 56% of the total
cation equivalents. For the remaining cations, average
contribution to total cation equivalents was 24% for
Mg2+, 17% for Na+, 3% for K+, and <1% for H+.
NH+
4 concentration was generally below the analytical
detection limit (<0.7 meq literÿ1). Streamwater ALK
was very low, averaging 28 meq literÿ1 and ranging from
ÿ14 to 110 meq literÿ1.
Fig. 3. Daily runo€ and longitudinal streamwater sampling periods at
Jezeri catchment X-16 for water years 1993 and 1994.
M. Havel et al. / Environmental Pollution 104 (1999) 157±167
161
Table 1
Correlation between streamwater constituent concentrations and elevation for the 27 stream sampling sites at the Jezeri X-16A catchment
Parameter
H (meq literÿ1)
ALK (meq literÿ1)
Na (meq literÿ1)
K (meq literÿ1)
Mg (meq literÿ1)
Ca (meq literÿ1)
Mn (meq literÿ1)
AlDIS (mmol literÿ1)
H4SiO4 (mmol literÿ1)
NH4 (meq literÿ1)
F (meq literÿ1)
Cl (meq literÿ1)
NO3 (meq literÿ1)
SO4 (meq literÿ1)
Sampling period (month/year)
XI/92
III/93
V/93
VIII/93
I/94
V/94
VIII/94
ÿ0.02
0.26
ÿ0.58
ÿ0.71
ÿ0.60
0.08
ÿ0.72
ÿ0.29
ÿ0.73
NA
ÿ0.84
ÿ0.47
0.88
ÿ0.77
0.18
0.32
ÿ0.50
ÿ0.71
ÿ0.75
ÿ0.47
ÿ0.88
ÿ0.14
ÿ0.54
0.48
ÿ0.88
ÿ0.85
0.59
ÿ0.80
ÿ0.59
0.73
ÿ0.43
ÿ0.72
0.08
0.72
ÿ0.64
ÿ0.70
ÿ0.38
0.04
ÿ0.91
ÿ0.79
0.88
ÿ0.92
ÿ0.54
0.72
ÿ0.11
ÿ0.20
0.05
0.83
ÿ0.38
ÿ0.60
ÿ0.48
0.23
ÿ0.89
ÿ0.40
0.86
ÿ0.91
ÿ0.30
0.58
0.39
ÿ0.48
ÿ0.14
0.54
ÿ0.77
ÿ0.48
0.49
ÿ0.11
ÿ0.90
ÿ0.81
0.86
ÿ0.92
ÿ0.62
0.79
ÿ0.62
ÿ0.66
ÿ0.90
0.34
ÿ0.49
ÿ0.75
ÿ0.69
NA
ÿ0.93
ÿ0.70
0.86
ÿ0.92
ÿ0.60
0.80
ÿ0.22
ÿ0.76
ÿ0.40
0.84
ÿ0.30
ÿ0.56
ÿ0.37
0.23
ÿ0.93
ÿ0.82
0.74
ÿ0.87
ALK, alkalinity; NA, not available.
4.2.2. Spatial trends
For some constituents, concentrations were highly
correlated with elevation for each sampling period
(Table 1) and these trends were the most uniform
through the beech zone (Figs. 4±6). Generally, stream+
water Mg2+, K+, Fÿ, Clÿ, SO2ÿ
4 , H4SiO4, H , and
AlDIS concentrations increased downstream from site
2+
con18 in the transition zone, whereas NOÿ
3 and Ca
centrations and ALK generally decreased downstream
through all sampling sites. In addition, constituent concentrations generally varied consistently within speci®c zones, but the patterns di€ered among zones and
with sampling period. Some of these patterns include:
(1) pronounced concentration decreases or increases
downstream from the highest elevation sites in the deforÿ
ÿ
ested zone (Ca2+, Mg2+, SO2ÿ
4 , Cl , F ); (2) local
maxima or minima in the deforested zone (H+, AlDIS,
Fÿ) or the transition zone (ALK, Ca2+, Na+, H4SiO4);
(3) a consistent concentration gradient through the
deforested zone that is considerably di€erent and
sometimes opposite to that through the beech zone
+
2+
); and (4) a trend reversal
(H4SiO4, NOÿ
3 , Ca , Mg
during some sampling periods (Ca2+, Na+).
Fig. 4. Relation between streamwater cation concentrations (Ca2+,
Mg2+, Na2+, K+) and elevation for each sampling period (month/
year) at Jezeri catchment X-16A.
4.2.3. Temporal trends
Although general elevational trends were observed
for most constituents, reversals of the general trends
occurred for some constituents during some sampling
periods and, in particular, during the III/93 sampling period. The gradient of elevational trends within
zones, or the concentration variations within a zone
where gradients were not apparent, varied among sampling periods for most constituents. Some constituent
concentrations varied seasonally and with ¯ow, whereas
patterns for other constituents were consistent throughout the year.
162
M. Havel et al. / Environmental Pollution 104 (1999) 157±167
Fig. 5. Relation between streamwater anion concentrations (Fÿ, Clÿ,
2ÿ
NOÿ
3 , SO4 ) and elevation for each sampling period (month/year)
at Jezeri catchment X-16A.
During the high runo€ (III/93), streamwater concentrations of most constituents behaved quite di€erently than during other sampling periods (Figs. 4±6).
Compared to the other sampling periods, concentrations of the base cations (Ca2+, Mg2+, Na+), SO2ÿ
4 ,
and H4SiO4 were the lowest at most of the sites and
concentrations of H+, AlDIS, Fÿ, and K+ were the
highest.
Streamwater NOÿ
3 concentrations varied seasonally.
During the dormant season (V/92, III/93, I/94) concentrations in the beech zone were 10 meq literÿ1, but
during the late spring and summer (May and August),
were only 60 meq literÿ1 (Fig. 5). During the growing
season, NOÿ
3 concentrations also decreased slightly,
downstream of the pond (Fig. 5).
Clÿ, which is routinely considered to be a conservative and mobile constituent, varied markedly both temporally and spatially (Fig. 5). In contrast with NOÿ
3,
Fig. 6. Relation between streamwater weathering/acidi®cation components (H+, AlDIS, ALK, H4SiO4 concentrations) and elevation for
each sampling period (month/year) at Jezeri catchment X-16A.
the highest streamwater Clÿ concentrations (>75 meq
literÿ1) occurred during late summer (VIII/93, VII/94)
and fall (XI/92). Lowest streamwater Clÿ concentrations occurred during the spring immediately following
snowmelt (V/93, V/94).
There was a general pattern of streamwater Na+
concentrations with ¯ow and season; the highest
Na+ concentrations (270 meq literÿ1) occurred during
base¯ow (VIII/93, VHIII/94) and the lowest (120 meq
literÿ1) at the onset of snowmelt (III/93).
Concentrations of AlDIS, H+, ALK, and Fÿ were
also related to ¯ow and season. The highest AlDIS, H+
and Fÿ concentrations and the lowest ALK occurred
during high runo€ in winter and the lowest concentrations occurred during low runo€ in late summer. For
each site, ALK was correlated with runo€; the highest
ALK occurred during low runo€ (VIII/93, VIII/94) and
the lowest during high runo€ (XI/92, III/93, I/94).
M. Havel et al. / Environmental Pollution 104 (1999) 157±167
4.2.4. Relations among constituents
Streamwater Ca2+ and Mg2+ concentrations are
positively correlated. However, the variance explained
by a linear regression of Ca2+ on Mg2+ varies along the
elavational gradient (r2 varies from 0.50 to 0.95). In
the deforested and transition zones, the areas where the
Ca2+ concentration gradient was the highest, Ca2+
concentrations for individual sampling periods are
highly correlated (r>0.75) with NOÿ
3 (Fig. 7). For the
deforested and transition zones, the slope of a linear
regression of Ca2+ on NOÿ
3 concentration for individual sampling periods ranges from 0.8 to 1.5.
Concentrations of H+, Fÿ, ALK and AlDIS correlate
with each other. For all of the data, a linear regression
of H+ on AlDIS concentrations produced an r2 of 0.85
(<0.0001) and a slope of 0.5, with little variability in
the slope of the relations among zones (Fig. 8). A linear
regression for H+ on Fÿ was more variable (r2=0.39,
<0.0001) than that for H+ on AlDIS and had a slope
of 0.5. However, a linear regression of H+ on Fÿ for
individual sites was highly sign®cant (median r2=0.90
and <0.01 for 25 of 27 sites), but the slopes varied
along the transect.
163
characteristics (landscape manipulation, vegetation) and
was used here as a surrogate for causality. In general,
landscape manipulations decreased downstream and the
forest becomes increasingly more stable and mature
downstream. The observed patterns in chemical concentrations re¯ect processes and dynamics that were not
apparent from long-term monitoring at the basin outlet.
Processes a€ecting the dominant constituents and the
acid-base status of streamwaters are discussed below.
5.1. E€ects of vegetation cover and landscape
manipulations
Several spatial and temporal patterns in the observed
streamwater chemistry may be attributed to controls
by land-use history (deforestation, landscape manipulation, liming, reforestation) and hydrology, which
controls the storage and transport of constituents.
Concentrations either increased or decreased downstream, and patterns varied depending on the constituent, runo€ at the time of sampling and the season.
Elevation is highly correlated with various catchment
5.1.1. Sulfate
The e€ects of vegetation cover and landscape type
on streamwater chemistry in small catchments, which
have been impacted by acidic atmospheric deposition, have been reported elsewhere (Johnson et al., 1981;
Driscoll et al., 1987a, b, 1988; Reynolds et al., 1994;
Probst et al., 1995; Wolock et al., 1997). Driscoll et al.
(1988) compared the chemistry of drainage waters at
two sites with di€erent loadings of acid deposition. For
the more impacted site at the Hubbard Brook Experimental Forest, New Hampshire (USA), streamwater
SO2ÿ
4 concentrations were highest in the headwaters and
concentrations either remained relatively constant or
decreased downstream. The trend was attributed to different deposition loadings due to di€erent vegetation
types. Streamwater SO2ÿ
4 concentrations remained constant (100 meq literÿ1), with elevation in the catchment
dominated by deciduous vegetation. In the other catchment, vegetation changed from coniferous to deciduous
concentrations decreased from
and streamwater SO2ÿ
4
150 to 110 meq literÿ1 downstream because the deciduous vegetation was less ecient in scavenging dry
deposition than the coniferous vegetation.
Fig. 7. Relation between streamwater Ca2+ and NOÿ
3 concentrations
for selected sampling periods (month/year) at sites 14±27 in the
transition and deforested zones of the Jezeri catchment X-16A.
Fig. 8. Relation between streamwater H+ and AlDIS concentrations
for all samples subset by vegetation zone at Jezeri catchment X-16A.
5. Discussion
164
M. Havel et al. / Environmental Pollution 104 (1999) 157±167
Lower streamwater SO2ÿ
4 concentrations at the higher
elevations of X-16A have similar associations with the
development of the vegetation cover. The spruce forest
was an e€ective ®lter for dry deposition, particularly
SO2. Cloud deposition also is extremely important
(Moldan, 1991; Elias et al., 1995) and enhanced
S deposition to the relatively large surface area of the
former mature spruce forest compared to the current
status of deforestation and reforestation. Throughfall
measurements at Jezeri in 1994 and 1995 indicate that
dry deposition to mature spruce is still extremely high
(126 kg S haÿ1 in 1994, Havel et al., 1996). Likewise,
higher N and F deposition must have occurred prior to
deforestation due to the relatively high dry deposition
component of these elements. Spruce decline in the
catchment signi®cantly reduced the total annual atmospheric deposition to the catchment, particularly at the
conhighest elevations. The low streamwater SO2ÿ
4
centrations at higher elevations, therefore, re¯ects
decreased deposition.
concentrations.
Other processes also a€ect SO2ÿ
4
Deforestation reduces evapotranspiration (ET), and
increases ¯ushing and water yields (Bosch and Hewlett,
1982), which is consistent with the discharge measurements made at some longitudinal sites in 1994. In
addition to the reduced atmospheric deposition, the
increased ¯ushing would also decrease streamwater
concentrations, compared to pre-dieback condiSO2ÿ
4
tions. Adsorption of S in the regolith is also expected to
a€ect the mobility of S. Some S continues to be mobilized from storage that accumulated during the earlier
high deposition period and S desorption is a€ected by
concentrations, soil acidity and
soil solution SO2ÿ
4
hydrologic pathways (Reuss and Johnson, 1986; Marsh
et al., 1992). Liming increases soil pH and sulfate
leaching, at least on the short-term (Korentajer et al.,
1983). The decreased atmospheric deposition and subsequent loss of SO2ÿ
4 due to lime applications and other
landscape changes, such as excavations for drainage,
concentrations to
probably caused streamwater SO2ÿ
4
decrease in the deforested and transition zones.
concentrations at lowest
Highest streamwater SO2ÿ
4
deposition to the
elevations result from high SO2ÿ
4
mature beech forest, and presumably SO2ÿ
4 desorption
and mobility along longer groundwater ¯ow paths.
A comparison of groundwater SO2ÿ
4 concentrations in
wells and springs in 1955±69 to those in 1980±90 (Hrkal,
1992) are consistent with the streamwater results of this
study. Hrkal (1992) reported that for groundwater sampled above 800 m, SO2ÿ
4 concentrations decreased from
645 to 479 meq literÿ1, but at lower elevations SO2ÿ
4 concentrations increased from 750 to 937 meq literÿ1. The
general groundwater SO2ÿ
4 concentration increase from
higher to lower elevations is attributed to higher atmospheric S deposition to the mature forest at lower elevations and the mobility of high SO2ÿ
4 concentrations in
groundwater with a long residence time, i.e. long enough
to re¯ect the pre-dieback deposition in the upper elevations. A few samples of springwater near sites 10 and 23
in 1997 also show a similar pattern with the higher SO2ÿ
4
concentrations at the lower elevation site (1160 and 900
at sites 10 and 23, respectively; Mirek Havel, Czech
Geological Survey 1997, unpublished data).
5.1.2. Nitrate
High streamwater NOÿ
3 concentrations, particularly
in the headwaters, indicates an imbalance between N
supply and demand (Aber et al., 1989; Hauhs et al.,
1989). At X-16A, lower concentrations (55±140 meq
literÿ1) occur at the outlet than at the highest elevation
(230±300 meq literÿ1). Furthermore, the highest NOÿ
3
concentrations are associated with the lowest SO2ÿ
4 concentrations in streamwater. As suggested for SO2ÿ
4 , the
loss of canopy reduced the total N deposition. The high
NOÿ
3 concentrations, therefore, did not result from
direct increases in atmospheric N deposition. However,
nutrient loss in drainage waters has been shown to
accelerate after destructive disturbance, such as forest
harvesting, clear cutting or dieback (Likens et al., 1977;
Swank and Caskey, 1982; Clayton and Kennedy, 1985;
Lawrence et al., 1987; Blackburn and Wood, 1990;
Reynolds et al., 1995). Increased temperature and
moisture availability accelerate the mineralization
and nitri®cation of the forest ¯oor (Smallidge et al.,
1993). Furthermore, after the forest died, N was
not readily utilized by biota and N was readily lost as
NOÿ
3 to streamwater or groundwater. Nitri®cation is
thought to be inhibited by acidity, although Gundersen
and Rasmussen (1988) suggest that nitri®cation can
proceed in very acidic forest soil. However, liming
increases soil pH and, consequently, can increase nitri®cation rates (Smallidge et al., 1993; Simmons et al.,
1996). In the transition zone, however, where trees are
older (>8 years older) and growth is more vigorous,
NOÿ
3 concentrations were considerably lower during the
growing season than in the deforested zone (Fig. 5).
The same pattern of decreasing streamwater NOÿ
3 concentrations downstream in a catchment in the Great
Smokey Mountains, USA, was reported by Flum and
Nodvin (1995); but the decrease was attributed to a
decreased N retention by old-growth forests at higher
elevations, a reverse of the vegetation pattern at Jezeri.
Streamwater NOÿ
3 concentrations were assessed previously for samples collected at di€erent elevations of
X16-A in June 1986 (Vladimir Kinkor, Czech Geological Survey 1986, unpublished data). In 1986 at Jezeri,
ÿ1
at
the NOÿ
3 concentration maximum was 350 meq liter
ÿ1
site 27 and decreased to 103 meq liter at site l. In the
deforested zone, 1986 NOÿ
3 concentrations were 30±80%
higher than in 1994, whereas in the beech zone, 1986
NOÿ
3 concentrations were similar to those in 1994. The
e€ects of liming on soil pH and, consequently, increased
M. Havel et al. / Environmental Pollution 104 (1999) 157±167
nitri®cation can be short-term (Smallidge et al., 1993).
The combined e€ects of depletion of N from the forest
¯oor, the continued but decreasing e€ects of liming (the
catchment was last limed in 1989), and the increasing
growth of reforested vegetation in the deforested zone
are hypothesized to be the dominant controls on the
observed decrease in streamwater NOÿ
3 concentrations
there.
5.1.3. Calcium and magnesium
In other studies, base cation concentrations typically
increase with increasing water residence time or ¯ow
path distance due to base cation release from mineral
weathering (Peters and Murdoch, 1985; Peters and
Driscoll, 1987). In contrast, Ca2+ and Mg2+ concentrations at X16-A were highest in the headwaters and
decreased downstream through the deforested zone.
This trend is opposite of what would be expected from
the increasing residence time hypothesis. The high
concentrations in the deforested zone are attributed
to landscape manipulation (land drainage and disturbance) and liming (Frouz, 1993; Newton et al., 1996).
The decoupling of Ca2+ and Mg2+ trends in the transition zone was unexpected because the dolomitic lime,
which contains both constituents, was heavily applied
in the dieback area. However, the Ca2+ concentrations
through deforested and transition zones are highly corÿ
related with NOÿ
3 concentrations. The NO3 decrease is
attributed to uptake by vegetation and the decrease in
Ca2+ may simply be a response of the loss of NOÿ
3 to
maintain electroneutrality.
5.2. E€ects of time and ¯ow
In the lower transition zone and upper beech zone,
SO2ÿ
4 concentrations were the highest during XI/92. The
high SO2ÿ
4 concentrations are attributed to S mobilization from the upper soil horizons. More water is available to percolate through the soil and ¯ush SO2ÿ
4
during the dormant season, causing a relative dilution
of streamwater SO2ÿ
4 concentrations. The possible processes controlling the S accumulation and enrichment
include atmospheric S deposition to the soil (mainly
dry deposition), ET enrichment and S mineralization.
NOÿ
3 concentrations in streamwater are primarily
a€ected by biological activity (Likens et al., 1977;
Edwards et al., 1985) and vary seasonally, i.e. lower
concentrations during the growing season when biological uptake is the greatest. Seasonality in NOÿ
3 concentrations occurs over the long term at Jezeri; the
seasonal pattern occurs at each site along the longitudinal gradient. Also, NOÿ
3 concentrations remain
high during the dormant season in the transition zone,
even with the high demand of the relatively vigorous
regrowing forest, and downstream in the mature forest
of the beech zone (Fig. 5).
165
5.3. Controls on the acidi®cation of streamwater
Prior to the landscape manipulations and lime
additions, Ca2+ and Mg2+ were primarily supplied by
the soil exchange complex (Paces, 1985). The evidence
for this is that the S deposition and transport greatly
exceeds the base cation resupply rate calculated for
weathering (Paces, 1985) and, consequently, the soil
cation-exchange sites were severely depleted (Kubelka et
al., 1992). During the period of maximum forest decline,
the surface 10±20 cm of the soil was so severely depleted
in exchangeable base cations that soil pH ranged from
2±3 and base saturation was less than 10% (Kubelka
et al., 1992). The liming resupplied Ca2+ and Mg2+ and
was a major source of ALK to bu€er against current
inputs of acidic atmospheric deposition. The ALK is
highest in the deforested and limed areas of the catchment and, although the supply is sucient to provide
low to moderate ALK (30±100 meq literÿ1) during low
runo€, the supply is rapidly depleted during high runo€
in the spring (XI/92, I/94, III/93). The increased ALK
and associated ALK decreases with increasing runo€
are similar to those observed in a whole catchment
liming experiment in the northeastern United States
(Newton et al., 1996).
Streamwater in the X-16A catchment is relatively
sensitive to acidi®cation; pH in 45% of the samples was
less than 5.6 and ALK in 90% of the samples was less
than 50 meq literÿ1. Although pH and ALK are relatively
high during low runo€ periods in the deforested and
transition zones (Fig. 6), the lower pH and ALK during
higher runo€ and at lower elevations are in the range of
controls by Al and associated organic complexes (Neal
et al., 1990). Furthermore, as discussed in the results,
ALK, and H+, Fÿ, and AlDIS concentrations are highly
correlated with each other regardless of whether they
are evaluated in total or grouped by sampling period,
sampling site or vegetation zone. In particular, linear
regressions of H+ on AlDIS concentrations are signi®cant (r2>0.8; a<0.01) regardless of grouping (cover
type, date or site), and regression slopes are consistent,
varying around 0.4. If all of the AlDIS in each sample
was inorganic monomeric (Al3+) and was the control
on H+, then the slope of the regressions would be 0.33.
Although Al species were not determined on these
samples, the excellent relationship between H+ and
AlDIS suggests that Al, as monomeric Al and organic
complexes with Al and F, control streamwater H+ at
Jezeri (Driscoll et al., 1987a, b; Lawrence et al., 1987;
Grieve, 1990).
6. Summary
Longitudinal streamwater chemical patterns at Jezeri
are consistent with land-use history and hydrology. At
166
M. Havel et al. / Environmental Pollution 104 (1999) 157±167
the highest elevations of the catchment in the deforested zone, the landscape has been highly manipulated,
including deforestation (dieback and removal of spruce),
liming and reforestation. At intermediate elevations
in the transition zone, the landscape has been manipulated as in the deforested zone, but was reforested earlier
(8±10 years older) and the regrowth is healthier and
more vigorous than in the deforested zone. At the lower
elevations in the beech zone, the landscape is natural
and consists of a mature beech forest. The streamwater
chemical patterns derived from seven sample collections
at 27 sites, conducted approximately quarterly from
November 1992 through November 1994, re¯ect a ®ner
view of controlling processes that were not apparent
from long-term monitoring at the basin outlet.
Streamwater SO2ÿ
4 concentrations are relatively constant for indivdual sites and generally increase with
decreasing elevation. This gradient is attributed to the
forest dieback and removal, and site remediation in
the upper elevations of the catchment. The loss of
canopy in the headwaters decreased the S supply, i.e.
dry S deposition, and increased soil moisture and water
yields. The result was an increase in the ¯ushing of
existing SO2ÿ
4 which, on the long-term, lowered streamwater SO2ÿ
4 concentrations. Liming changed the soil pH
leaching. Higher SO2ÿ
concentraand increased SO2ÿ
4
4
tions downstream are hypothesized to result from continued high dry S deposition to the surrounding mature
beech forest and contributions of high SO2ÿ
4 concentration groundwater to streamwater.
In contrast, the streamwater NOÿ
3 concentrations are
highest (300 meq literÿ1) in the most recently manipulated area of the watershed at the highest elevations
and decreased downstream. Nitri®cation of decomposing organic matter is the main source of streamwater
NOÿ
3 in the deforested and transition zones. The forest
is older and healthier downstream in the transition zone
and has a high N requirement. Regrowing stands of
birch, mountain ash and young spruce at the higher
elevations, particularly in the transition zone, are utilizing N for internal cycling. Streamwater concentrations
in the transition and beech zones varied seasonally.
Temporal and spatial trends in streamwater Ca2+
and Mg2+ concentrations are a€ected by lime, which
was applied as dolomitic limestone to the deforested
and transition zones in the headwaters during the 1980s.
The highest Ca2+ and Mg2+ concentrations occur in
the headwaters. The increased soil pH due to liming can
also increase nitri®cation rates. As a result, streamwater
Ca2+ and NOÿ
3 concentrations were highly correlated,
particularly in the transition zone.
Streamwater is sensitive to acidi®cation at Jezeri
where pH was less than 5.6 in 45% of the samples and
ALK was less than 50 meq literÿ1 in 90% of the samples.
High correlations among H+, Fÿ, and AlDIS concentrations and ALK suggest controls of streamwater
acid-base chemistry by inorganic Al and Al±F organic
complexes.
Acknowledgements
This research was supported by the Czech Ministry
of the Environment, and Czechoslovak±American
Commission under project No. 94018, entitled `hydrogeochemical analysis of water pathways and geochemical factors a€ecting forest dieback in an area of high
deposition of atmospheric pollutants', which is part of
the US±Czech Science and Technology Agreement
between the Czech and United States Geological Surveys. We are grateful to Radovan KrejcõÂ, Jan Havrda,
Pavel Walter, Pavel Sobotka and Svetla MatouskovaÂ
for ®eld support and Hyacinta VõÂtkovaÂ, Pavel Pokorny
and Petr Foch for laboratory support. The review comments by Owen Bricker and Greg Lawrence are also
appreciated. The use of brand names in this report is for
descriptive purposes only and does not imply endorsement by the US Geological Survey.
References
Aber, J.D., Nadelho€er, K.J., Steudler, P., Melillo, J.M., 1989.
Nitrogen saturation in northern forest ecosystems. Bioscience 39,
378±386.
Ardo, J., Lambert, N., Henzlik, V., Rock, B.N., 1997. Satellite-based
estimations of coniferous forest cover changes: Krusne Hory, Czech
Republic 1972±1989. Ambio 26(3), 158±166.
Blackburn, W.H., Wood, J.C., 1990. Nutrient export in storm¯ow
following forest harvesting and site preparation in East Texas.
Journal of Environmental Quality 19(3), 402±408.
BoÈer, W., Vesecky, A., 1975. Climate and Weather Conditions in Ore
Mountains. Czech Hydrometeorological Institue, Prague (in Czech).
Bosch, J.M., Hewlett, J.D., 1982. A review of catchment experiments
to determine the e€ect of vegetation changes on water yield and
evapotranspiration. Journal of Hydrology 55, 3±23.
Cerny, J., 1995. Recovery of acidi®ed catchments in the extremely
polluted Krusne Hory Mountains, Czech Republich. Water, Air,
and Soil Pollution 85, 589±594.
Cerny, J., Havel, M., 1995. Hydrogeochemical Studies of Surface
Waters in the Krusne Hory Mts. Research Report of the project
Complex investigations in the North Bohemia Coal Basin, Topic
Hydrosphere DU 05, Czech Geological Survey, Prague (in Czech).
Clayton, J.L., Kennedy, D.A., 1985. Nutrient losses from timber
harvest in the Idaho Batholith. Soil Science Society of America
Journal 49, 1041±1049.
Driscoll, C.T., Wyskowski, B.J., Cosentini, C.C., Smith, M.E., 1987a.
Processes regulating temporal and longitudinal variations in the
chemistry of a low-order woodland stream in the Adirondack region
of New York. Biogeochemistry 3, 225±241.
Driscoll, C.T., Yatsko, C.P., Unangst, F.J., 1987b. Longitudinal and
temporal trends in the water chemistry of the North Branch of the
Moose River. Biogeochemistry 3, 37±61.
Driscoll, C.T., Johnson, N.M., Likens, G.E., Feller, M.C., 1988.
E€ects of acidic deposition on the chemistry of headwater streams:
a comparison between Hubbard Brook, New Hampshire, and
Jamieson Creek, British Columbia. Water Resources Research
24(2), 195±200.
M. Havel et al. / Environmental Pollution 104 (1999) 157±167
Edwards, A.C., Creasy, J., Cresser, M.S., 1985. Factors in¯uencing
nitrogen inputs and outputs in two Scottish upland catchments.
Soil Use and Management 1(3), 83±87.
Elias, V., Tesar, M., Buchtele, J., 1995. Occult precipitation: sampling,
chemical analysis and process modelling in the Sumava Mts (Czech
Republic) and in the Taunus Mts (Germany). Journal of Hydrology
166(3/4), 409±420.
Flum, T., Nodvin, S.C., 1995. Factors a€ecting streamwater chemistry
in the Great Smokey Mountains, USA. Water, Air, and Soil Pollution 85, 1707±1712.
Frouz, J., 1993. Development of cutting and liming in watersheds of
Vesnicky and Sramnicky brook. Unpublished manuscript (in Czech).
Gran, G., 1952. Determination of the equivalence point in potentiometirc titrationsÐpart II. The Analyst 77, 661±671.
Grieve, I.C., 1990. E€ects of catchment liming and a€orestation on the
concentration and fractional composition of aluminum in the Loch
Fleet catchment, SW Scotland. Journal of Hydrology 115, 385±396.
Gundersen, P., Rasmussen, L., 1988. Nitri®cation, acidi®cation and
aluminium release in forest soils. In: Nilsson, J., Grenfelt, P. (Eds.),
Critical Loads for Sulphur and Nitrogen. Environmental Report V,
1988/15, Nordic Council of Ministers, Copenhagen.
Hauhs, M., Rost-Siebert, K., Raben, G., Paces, T., Vigerust, T., 1989.
Summary of European data. In: Malanchuk, J.L., Nilsson, J. (Eds.),
The Role of Nitrogen in the Acidi®cation of Soils and Waters.
Milojrapport 10, part 5, pp. 1±37. Nordic Council of Ministers,
Copenhagen.
Havel, M., KrejeÁõÂ, R., Cerny, J., 1996. Decrease of Acid Atmospheric
Deposition in the Krusne hory Mts. Project Report, Grant Agency
of the Czech Republic, Project No. 205/93/0675 (in Czech).
Hrkal, Z., 1992. Acidi®cation of groundwater in the Bohemian
Massif. Norges Geologeske Undersokelse Bulletin 422, 97±102.
Jirgle, J., 1984. Causes of withering some substitute forest stands in
the Krusne hory Mts. Zprava Lesnickeho Vyzkumu, 24(2) 5±21
(in Czech).
Jirgle, J., 1988. Ecological conditions for forest reconstruction in the
Krusne hory Mts. Lesnicka Prace 67(7), 312±322 (in Czech).
Johnson, N.M., Driscoll, C.T., Eaton, J.S., Likens, G.E., McDowell,
W.H., 1981. `Acid rain', dissolved aluminum and chemical weathering at the Hubbard Brook Experimental Forest, New Hampshire.
Geochimica Cosmochimica Acta 45, 1421±1437.
KobrovaÂ, M., 1983. Methods of the Chemical Analysis of Natural
Waters. Czech Geological Survey, Prague.
Korentajer, L., Byrnes, B.H., Hellums, D.T., 1983. The e€ect of liming
and leaching on the sulfur-supplying capacity of soils. Soil Science
Society of America Journal 47, 525±530.
Kubelka, L., KaraÂsek, A., RybaÂù, A., BadalõÂk, V., SlodieÁaÂk, M., 1992.
Restoration of the Emission Endangered Forest in the Northeast
Krusne Hory Mts. Ministry of Agriculture of the Czech Republic,
Prague.
Lawrence, G.B., Fuller, R.B., Driscoll, C.T., 1987. Release of aluminum following whole-tree harvesting at the Hubbard Brook
Experimental Forest, New Hampshire. Journal of Environmental
Quality 16(4), 383±390.
Likens, G.E., Bormann, H.F., Pierce, R.S., Eaton, J.S., Johnson,
N.M., 1977. Biogeochemistry of a Forested Ecosystem. SpringerVerlag, New York.
Marsh, K.B., Tillman, R.W., Syers, J.K., 1992. E€ect of changes in
pH on sulphate and phosphate retention in soils. New Zealand
Journal of Agricultural Research 35, 93±100.
167
Moldan, B., 1991. Atmospheric deposition: a biogeochemical process.
Rozpravy Ceskoslovenske Akademie Ved (The Czech Academy of
Sciences Discussions Series), Rada matematickych a prirodnich
ved (Mathematical and Naturale Sciences Edition) 101(l), Czech
Academy of Sciences, Praha.
Moldan, B., Schnoor, J.L., 1992. Czecho-slovakia examining a
critically ill environment. Environmental Science and Technology
26(1), 14±21.
Neal, C., Reynolds, B., Stevens, P.A., Hornung, M., Brown, S.J.,
1990. Dissolved inorganic aluminum in acidic stream and soil waters
in Wales. In: Edwards, R.W., Gee, A.S., Stoner, J.H. (Eds.), Acid
Waters in Wales. Monographiae Biologicae, pp. 173±188.
Newton, R.M., Burns, D.A., Blette, V.L., Driscoll, C.T., 1996. E€ect
of whole catchment liming on the episodic acidi®cation of two
Adirondack streams. Biogeochemistry 32, 299±322.
Paces, T., 1985. Sources of acidi®cation in Central Europe estimated
from elemental budgets in small basins. Nature 315, 31±36.
Patrik, M., 1988. Geochemistiry of the bedrock in the acidi®ed JezerõÂ
catchment. Diploma thesis, University of J. PurkynõÁ, Brno (in
Czech).
Peters, N.E., Driscoll, C.T., 1987. Hydrogeologic controls of surfacewater chemistry in the Adirondack Region of New York State.
Biogeochemistry 3, 163±180.
Peters, N.E., Murdoch, P.S., 1985. Hydrogeologic comparison of an
acidic-lake basin with a neutral-lake basin in the west-central
Adirondack Mountains, New York. Water, Air, and Soil Pollution
26, 387±402.
PlõÂva, K., ZlaÂbek, I., 1986. Natural forest regions of EÁSR. Ministry of
Forest and Water Management, Prague (in Czech).
Probst, A., Probst, J.L., Massabuau, J.C., Fritz, B., 1995. Surface
water acidi®cation in the Vosges mountains: relation to bedrock
and vegetation cover. In: Landmann, G., Bonneau, M. (Eds.),
Forest Decline and Atmospheric Deposition E€ects in the French
Mountains. Springer-Verlag, New York, pp. 371±386.
Reuss, J.O., Johnson, D.W., 1986. Acid deposition and the acidi®cation of soils and waters. Ecological Studies 59, Springer-Verlag,
New York.
Reynolds, B., Ormerod, S.J., Gee, A.S., 1994. Spatial patterns in
stream nitrate concentrations in upland Wales in relation to
catchment forest cover and forest age. Environmental Pollution 84,
27±33.
Reynolds, B., Stevens, P.A., Hughes, S., Parkinson, J.A., Weatherley,
N.S., 1995. Stream chemistry impacts of conifer harvesting in Welsh
catchments. Water, Air, and Soil Pollution 79, 147±170.
Sach F., 1990. Mechanical Soil Preparation with Special Emphasis on
Minimising Soil Degradation by Erosion. Final Report. Forest and
Game Management Research Institute, Strnady (in Czech).
Simmons, J.A., Yavitt, J.B., Fahay, T.J., 1996. Watershed liming
e€ects on the forest ¯oor N cycle. Biogeochemistry 32, 221±244.
Smallidge, P.J., Brach, A.R., Mackun, I.R., 1993. E€ects of watershed
liming on terrestrial ecosystem processes. Environmental Review 1,
157±171.
Swank, W.T., Caskey, W.H., 1982. Nitrate depletion in a secondorder mountain stream. Journal of Environmental Quality 11(4),
581±584.
Wolock, D.M., Fan, J., Lawrence, G.B., 1997. E€ects of basin size on
low-¯ow stream chemistry and subsurface contact time in the
Neversink River watershed, New York. Hydrological Processes
11(9), 1273±1286.