Effects of a rainstorm high in sea-salts on labile inorganic aluminium in drainage from the acidified catchments of Lake Terjevann, southernmost Norway
Do. Andersen et Hm. Seip, Effects of a rainstorm high in sea-salts on labile inorganic aluminium in drainage from the acidified catchments of Lake Terjevann, southernmost Norway, J HYDROL, 224(1-2), 1999, pp. 64-79
The acidification of many streams and lakes that has occurred in southern N
orway during several decades is to a large extent caused by acid deposition
. However, in coastal areas deposition events with high loading of sea-salt
s may result in increased acidity and aluminium concentration in the discha
rge. Since such episodes are difficult to predict and usually of short dura
tion, the aluminium chemistry during such episodes has so far not been eval
uated in detail. In January 1993, during monitoring of streams in the Lake
Terjevann catchment, the area was exposed to an extraordinary high sea-salt
loading. The Cl- concentration in the stream water more than doubled (reac
hing about 900 mu eq/l), the labile inorganic aluminium (Ali) concentration
almost quadrupled (reaching about 33 and 18 mu M in the two streams), and
the relative increase in the Al3+ concentration was even higher. It took 3-
4 months until the Al-i concentration and almost a year until the Cl- conce
ntration returned to pre-event levels. Simple equilibria with minerals such
as gibbsite, jurbanite, kaolinite/halloysite or imogolite do not control a
luminium concentration in the discharge from these catchments. Retention of
Na+ more than compensated for the desorption of Al3+. The results strongly
indicate that cation exchange in the organic soil layers was essential in
controlling the aluminium chemistry in the stream waters especially during
high flow. Similar, but less pronounced, effects of the sea-salt episode we
re seen at the Birkenes catchment about 37 km inland from Lake Terjevann. (
C) 1999 Elsevier Science B.V. All rights reserved.