Longitudinal streamwater sampling in a 210-ha forested catchment (Jezeri),
Czech Republic, was conducted approximately quarterly from August 1992 thro
ugh August 1994. The catchment has been severely impacted by atmospheric de
position of pollutants and subsequent landscape manipulation for reforestat
ion. The impact and landscape manipulations decrease with decreasing elevat
ion. The concentration patterns reflect processes and dynamics that are not
apparent from long-term monitoring at the basin outlet. Streamwater concen
trations of many solutes are highly correlated with elevation, vegetation c
over and landscape history. Concentrations of sulphate (SO42-), the dominan
t anion, increased downstream. Low SO42- concentrations at the highest elev
ations are attributed to a decrease in dry S deposition due to the loss of
the forest canopy from Norway spruce dieback and subsequent logging. Furthe
rmore, liming and higher moisture content and water movement through the so
ils in the headwaters increases S mobility, resulting in lower SO42- concen
trations at higher elevations. In contrast, highest nitrate (NO3-) concentr
ations (300 mu eq liter(-1)) occurred at the highest elevations, decreased
downstream to XO mu eq liter(-1) at the outlet, and the rate of change in c
oncentration was the most pronounced in the headwaters. The NO3- pattern is
attributed to increased nitrification of the forest floor due to landscape
excavation for drainage and reforestation, and liming (dolomitic lime). Th
e N demand by 10-25-year-old reforested vegetation at mid elevations (705-8
00 m above sea level) is much greater than in the very young regrowth and o
pen areas at the highest elevations, causing concentrations to decrease thr
ough this zone. Streamwater NO3- concentrations also vary seasonally due to
vegetation demand during the growing season; but high NO3- concentrations
(> 50 mu eq liter(-1)) persist at all sites, indicating N saturation. High
streamwater calcium (Ca2+) and magnesium (Mg2+) concentrations and low to m
oderate alkalinity (ALK) in the limed, deforested and reforested areas also
occur, particularly during low runoff periods. ALK and hydrogen ion (H+),
fluoride (F-) and dissolved aluminum (Al-DIS) concentrations are highly cor
related, particularly H+ and Al-DIS The low streamwater ALK tin 90% of the
samples ALK is less than 50 mu eq liter(-1)), moderately low pH tin 45% of
the samples pH is less than 5.6) and the correlation with Al-DIS suggests t
hat the acid-base status is controlled by inorganic Al and organic complexe
s of Al and F. Published by Elsevier Science Ltd.