Isotope fractionation of $sup 15$N and $sup 14$N in microbiological nitrogen transformations: a theoretical model

Journal Article · Mon Jan 01 00:00:00 EST 1973 · J. Environ. Qual., v. 2, no. 2, pp. 247-252

OSTI ID:4329942

Focht, D D

The kinetics for first-order multisequence reactions are derived for microbial fractionation of /sup 14/N and /sup 15/N isotopes. The isotope effect accounts for unreacted substrate becoming progressively enriched in the heavier isotope due to preferential utilization of the lighter isotope by microorganisms. Consequently, during denitrification nitrate becomes enriched in /sup 15/N as its concentration diminishes. This inverse proportional relationship is expressed as a hyperbolic function, Y = ax/sup -b/. Similar curves are derived for nitrate originating from ammonification and/or nitrification. Regression coefficients for a straight line approximation are better than --0.98, but not as good as the actual coefficients for the derived hyperbolic equations. A negative regression line'' for nitrate occurs for all denitrification reactions during isotope discrimination. Nitrate originating from casein, ammonium, and nitrate are respectively less enriched in /sup 15/N for equal nitrate concentration due to ammonium and nitrate being initially enriched in /sup 14/N during ammonification and nitrification, respectively. (auth)

• Research Organization: Univ. of California, Riverside
• NSA Number: NSA-29-026650
• OSTI ID: 4329942
• Journal Information: J. Environ. Qual., v. 2, no. 2, pp. 247-252, Other Information: Orig. Receipt Date: 30-JUN-74
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

N40230* -Chemistry-Inorganic
Organic
& Physical Chemistry-Isotope Exchange & Isotope Separation
N40220 -Chemistry-Inorganic
Organic
& Physical Chemistry-Isotopic Effects
*NITROGEN 14- ISOTOPE SEPARATION
*NITROGEN 15- ISOTOPE SEPARATION
AMMONIUM COMPOUNDS
CASEIN
CHEMICAL REACTION KINETICS
DENITRATION
ISOTOPE ENRICHED MATERIALS
MICROORGANISMS
NITRATES