Comparing denitrification estimates for a Texas estuary by using XXXX inhibition and membrane inlet mass spectrometry.

@entity14493 @entity26 @entity728 @entity3810 @entity2755
Characterizing denitrification rates in aquatic ecosystems is essential to understanding how systems may respond to increased nutrient loading. Thus, it is important to ensure the precision and accuracy of the methods employed for measuring denitrification rates. The @entity14493 ( @entity728 ) inhibition method is a simple technique for estimating denitrification. However, potential problems, such as inhibition of nitrification and incomplete inhibition of @entity3810 reduction, may influence rate estimates. Recently, membrane inlet mass spectrometry (MIMS) has been used to measure denitrification in aquatic systems. Comparable results were obtained with MIMS and @entity728 inhibition methods when @entity2755 was added to @entity728 inhibition assay mixtures to inhibit new synthesis of denitrifying enzymes. Dissolved- @entity26 profiles indicated that surface layers of sediment cores subjected to the MIMS flowthrough incubation remained oxic whereas cores incubated using the @entity728 inhibition methods did not. Analysis of the microbial assemblages before and after incubations indicated significant changes in the sediment surface populations during the long flowthrough incubation for MIMS analysis but not during the shorter incubation used for the @entity728 inhibition method. However, bacterial community changes were also small in MIMS cores at the @entity26 transition zone where denitrification occurs. The @entity728 inhibition method with @entity2755 addition, conducted over short incubation intervals, provides a cost-effective method for estimating denitrification, and rate estimates are comparable to those obtained by the MIMS method.
