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Nitrogen elimination in two deep eutrophic lakes
Author(s) -
Mengis Martin,
Gächter René,
Wehrli Bernhard,
Bernasconi Stefano
Publication year - 1997
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1997.42.7.1530
Subject(s) - denitrification , eutrophication , nitrogen cycle , environmental chemistry , hypolimnion , nitrogen , sediment , environmental science , isotopes of nitrogen , nitrification , nitrate , flux (metallurgy) , chemistry , hydrology (agriculture) , nutrient , geology , geomorphology , geotechnical engineering , organic chemistry
Nitrogen elimination was investigated in two eutrophic Swiss lakes with different hypolimnetic oxygen conditions. Nitrogen burial was estimated from sediment‐trap and sediment‐core studies. Denitrification and NO 3 − ‐ammonification rates were quantified with 15 NO 3 − and acetylene incubation experiments and whole‐lake mass balances. The study confirmed earlier reports that the acetylene‐block technique yields denitrification rates that are systematically too low. Denitrification rates obtained from isotope tracer experiments were compatible with nitrogen consumption rates observed in flux chamber experiments and whole‐lake mass balances. The NO 3 − ‐ammonification contributed <5% to the NO 3 − consumption rate in Lake Baldegg. Coupled nitrification‐denitrification seemed to be insignificant at the deepest station of Lake Baldegg. The comparison of in situ denitrification rates measured at the deepest site (4.3 mmol m −2 d −1 ) with the denitrification rate obtained from whole‐lake mass balances (6.1 mmolm −2 d −1 ) indicates that enhanced denitrification may be present in shallower sediments with a better supply of O 2 . Mass transfer coefficients for NO 3 − were similar in both lakes (21.7 and 21.4 m yr − ). The NO 3 − concentration seems to be a key parameter in determining denitrification rates.