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Influence of Oxygen and Sulfide Concentration on Nitrogen Uptake Kinetics in Spartina Alterniflora
Author(s) -
Bradley Paul M.,
Morris James T.
Publication year - 1990
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1940267
Subject(s) - spartina alterniflora , sulfide , chemistry , nitrogen , kinetics , ammonium , zoology , environmental chemistry , nuclear chemistry , biology , ecology , wetland , physics , marsh , organic chemistry , quantum mechanics
The effects of sulfide concentration and hypoxia on NH 4 @ ?—uptake kinetics in Spartina alterniflora were examined in a laboratory culture experiment. Both factors significantly influenced the Michaelis—Menten parameters, V m a x and K m , which characterize the nitrogen uptake rate as a function of nitrogen concentration. Under oxygen—saturated conditions, the mean NH 4 @ ? V m a x per unit root dry mass (DM) was 12.91 @mmol°g — 1 °h — 1 and the K m was 1.05 @mmol/L NH 4 @ ?+. Under hypoxia, V m a x decreased to 8.14 @mmol°g — 1 °h — 1 , while K m increased to 2.54 @mmol/L NH 4 @ ?+. Dissolved sulfide concentrations as low as 0.25 mmol/L inhibited the NH 4 @ ?+—uptake kinetics of S. alterniflora significantly, and to a greater extent than hypoxia alone. Exposure to 1.0 mmol/L sulfide resulted in a V m a x per unit root DM of 2.28 @mmol°g — 1 °h — 1 and a K m of 8.79 mmol/L NH 4 @ ?+. No significant NH 4 @ ?+ uptake was found with exposure to 2.0 mmol/L sulfide. The results are consistent with a conceptual model of changes in productivity of S. alterniflora in the salt marsh as a function of environmental modification of NH 4 @ ?+—uptake kinetics.