Nature387, 64 - 67
(01 May 1997); doi:10.1038/387064a0
Temperature effects on the acidity of remote alpine
lakes
Sabine Sommaruga-WÖgrath*†, Karin A. Koinig*, Roland Schmidt‡, Ruben Sommaruga*, Richard Tessadri§ & Roland Psenner*
*Institute of Zoology and Limnology,
University of Innsbruck, 6020 Innsbruck, Austria ‡Institute of Limnology, Austrian
Academy of Sciences, 5310 Mondsee, Austria §Institute of Mineralogy and Petrography,
University of Innsbruck, 6020 Innsbruck, Austria
Climate variations and changes in sulphur and nitrogen
deposition from the atmosphere influence the acid–base balance
of sensitive lakes in a complex and site-specific
way1–3. For example, although lakes in several
regions have shown a decline in sulphate concentration following
reductions in atmospheric sulphate
deposition4–6, the expected recovery of pH and
alkalinity has not always taken place, implicating an additional
response to changes in the local climate. Here we report a study of
57 remote alpine lakes which shows that, between 1985 and 1995, lake
pH and the concentration of sulphate, base cations and silica have
increased, whereas inorganic nitrogen concentrations have decreased.
This contrasts with atmospheric input trends, which have led to a
decrease in sulphate and a slight increase in nitrogen deposition
over the same period7,8. We propose that the changes
in lake chemistry are therefore likely to be caused by enhanced
weathering and increased biological activity resulting from an
increase in air temperature of about 1 °C since 1985. Our analysis of
an alpine lake core covering a 200-year period provides further
evidence for a strong positive correlation between pH and mean air
temperatures, and thus for the high sensitivity of lakes at high
altitudes and high latitudes to climate warming. In these remote
locations, temperature effects, rather than acid deposition, appear
to dominate changes in lake acidity.