Freshwater Ecosystems - Freshwater Ecology: Concepts and Environmental Applications - page 452

Nitrogen Budgets of Some Aquatic Systems Showing the Importance of Nitrogen Fixation and Denitrification a

TABLE 22.1

Inputs Outputs

Litter

Aquatic system Inflow deposition Atmospheric N 2 fixation Outflow Accumulation Denitrification Reference

Sphagnum bog 0 0 1.4 (95) 0.05 (5) 0.2 (15) 0.9 (71) 0.2 (13) Urban and Eisenreich (1988)

Riparian zone in 2.9 (56) ? 1.2 (24) 1.1 (20) 1.3 (33) 5.2 (54) 3.2 (33) Lowrance et al. (1984)

agricultural area
Groundwater fed fen in 2.1 (28) ? 4.2 (56) 1.3 (17) 21 (24) 6.6 (75) 0.1 (1) Koerselman et al. (1990)

agricultural area
River fed fen in 0.7 (14) ? 4.4 (82) 0.2 (4) 1.0 (20) 3.8 (76) 0.1 (3) Koerselman et al. (1990)

agricultural area
Eutrophic lake 0.3 (45) 0 0.06 (9) 0.3 (45) 0.4 (55) 0.3 (40) 0.03 (5) Horne and Goldman

(Clear Lake, California) (1972, 1994)

Eutrophic lake 3.2 (58) 0 1.7 (31) 0.6 (11) 1.6 (29) 3.0 (53) 1 (18) Messer and Brezonik (1983)

(Lake Okeechobee, Florida)
Spring pool with 27 (50) 24 (42) 2 (4) 2 (4) 36 (59) 25 (41) 0.6 (1) Dodds and Castenholz (1988)

dominant Nostoc
Desert stream 0.47 (92) ? ? 0.04 (8) 0.49 (89) 0.05 (11) ? Grimm and Petrone (1997)

Forest stream 11 (73) 3 (22) ? 1 (5) 11 (75) 4 (25) ? Triska et al. (1984)

Alpine streams/lakes 0.52 (57) 0 0.39 (43) ? 3 (99) ? 0.025 (1) Baron and Campbell (1997)

a Values in g N m 2 year 1 . Percentage of total input or output is shown in parentheses. Accumulation includes burial and storage in plant parts. When only accumulation is
listed and denitrification is not known, the value includes burial denitrification.