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Nitrogen Loss from Freshwater and Saline Estuarine Sediments
Author(s) -
Smith C. J.,
De Laune R. D.
Publication year - 1983
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1983.00472425001200040015x
Subject(s) - denitrification , sediment , ammonium , nitrous oxide , nitrate , nitrogen , nitrification , environmental chemistry , estuary , saline water , chemistry , zoology , salinity , hydrology (agriculture) , ecology , biology , geology , geotechnical engineering , paleontology , organic chemistry
The magnitude of ammonium‐N (NH 4 + ‐N) loss from nitrification‐denitrification reactions in bottom sediments collected from saline and freshwater Louisiana Gulf Coast lakes was determined. Studies were conducted in the laboratory and field. Maximum gaseous N accumulation, from fresh‐water and saline sediment amended with 4.5 µ g nitrate‐N (NO 4 − ‐N) g −1 (on dry‐wt basis), was 1.6 and 1.4 µ g N g −1 , respectively. The addition of 50 µ g NH 4 + ‐N g −1 stimulated the evolution of N 2 O from both sediments, and represents 0.02 and 0.2% of the NH 4 + ‐N applied to the saline and fresh sediment, respectively. Nitrous oxide (N 2 O) emissions measured in the field were low. The annual N 2 O emission was 10 and 34 mg N m −2 from the saline and freshwater lakes. These values agree closely with the N 2 O emission rates calculated from laboratory data. Denitrification was also estimated from NH 4 + ‐N amended sediment using the acetylene (C 2 H 2 ) inhibition technique and 15 N balance. Recovery of 15 N decreased rapidly during the 0‐ to 8‐week period when high denitrification rates were measured. The denitrification rate estimated from 15 N recovery during the 0‐ to 8‐week period was 3.7 mg N m −2 d −2 for each sediment. Approximately 50% of the added 15 N was lost, an amount equivalent to 1.4 g N m −2 y −1 . As the added 15 NH 4 + ‐N was incorporated into the organic N pool, little or no further 15 N was lost.