Logo image
Back
Effect of organic loading on nitrification and denitrification in a marine sediment microcosm
Journal article   Peer reviewed

Effect of organic loading on nitrification and denitrification in a marine sediment microcosm

J. M. Caffrey, N. P. Sloth, H. F. Kaspar and T. H. Blackburn
FEMS Microbiology Ecology, Vol.12, pp.159-167
12
1993
DOI: https://doi.org/10.1111/j.1574-6941.1993.tb00028.x

Metrics

57 Record Views

Abstract

The effects of organic additions on nitrification and denitrification were examined in sediment microcosms. The organic material, heat killed yeast ,had a C/N ratio of 7.5 and was added to sieved, homogenized sediments. Four treatments were compared: no addition (control), 30 g dry weight (dw) m⁻² mixed throughout the 10 cm sediment column (30M), 100 g dw m⁻² mixed throughout sediments (100M), and 100 g dw m⁻² mixed into top 1 crn (100S). After the microcosms had been established for 7-11 days, depth of O2 penetration, sediment-water fluxes and nitrification rates were measured. Nitrification rates were measured using three different techniques: N-serve and acetylene inhibition in intact cores , and nitrification potentials in slurries. Increased organic additions decreased O₂ penetration from 2.7 to 0.2 mm while increasing both O₂ consumption, from 30 to 70 mmol O₂ m⁻² d⁻¹ , and NO₃⁻ flux into sediments. Nitrification rates in intact cores were similar for the two methods. Highest rates occurred in the 30M treatment, while the lowest rate was measured in the 100S treatment. Total denitrification rates (estimated from nitrification and nitrate fluxes) increased with increased organic addition, because of the high concentrations of NO₃⁻ (40 µM) in the overlying water. The ratio of nitrification: denitrification was used as an indication of the importance of nitrification as the NO₃⁻ supply for denitrification. This ratio decreased from 1.55 to 0.05 with increased organic addition.

Details

Logo image