Eutrophication and the rate of denitrification and N₂0 production in coastal marine sediments

Abstract

Large (13 m3, 5 m deep) microcosms with coupled pelagic and benthic components were used to measure the effect of nutrient loading and eutrophication in coastal marine ecosystems on the rates of benthic denitrification (N2) and N2O production. After 3 months of daily nutrient addition, average denitrification rates ranged from about 300 µmol N m−2 h−1 in the sediments of the control microcosm to 880 in the most enriched microcosm. which received 65 times the nutrient input of the control. Increases in the production of N2O were more dramatic and increased by a factor of about 100, from 0.56 µmol N m−2 h−1 in the control to 51 in the most enriched microcosm. Although there was a clear increase in the denitrification rate in the more eutrophic systems, the amount of fixed nitrogen removed was a constant or progressively smaller fraction of the nitrogen input. Even in the most enriched microcosm, at least 16% of the N input was removed by denitrification.

Nitrous oxide in the Changjiang (Yangtze River) Estuary and its adjacent marine area: Riverine input, sediment release and atmospheric fluxes

“…A review by Capone suggests the fluxes from the sediments (predominantly in coastal areas) could account for over 40% of the net oceanic N 2 O production (Capone, 1991). High nutrient loading from terrestrial environments together with a close benthic and pelagic coupling due to shallow water depth stimulates microbial processes including N 2 O production (Seitzinger and Nixon, 1985;Middelburg et al, 1995;Bange et al, 1996;Seitzinger and Kroeze, 1998). Since the Changjiang estuary contains large amount of dissolved nitrogen species, one would expect high production and release of N 2 O from the sediments.…”

Denitrification in coastal bay sediment: regional and seasonal variation in Aarhus Bight, Denmark

“…Denitrification thus mitigates coastal nitrogen loading fl-om terrestrial sources (e.g. Seitzinger & Nixon 1985), and may in some cases limit coastal primary production (Boynton et al 1980, Nixon 1981. In order to estimate the role of denitrification in coastal eutrophication, it is of prime importance to determine the temporal and regional variations of the process and to identify the regulating environmental factors.…”

Individual and population indicators of Zostera japonica respond quickly to experimental addition of sediment-nutrient and organic matter

“…It may be because organic matter can induce sediment redox in the conditions of nutrient loading, which reduces the absorption of seagrass roots to N, especially nitrate available forms by denitrification from bacterial metabolism (Peralta et al, 2003;Udy and Dennison, 1997b;. In the conditions of higher nutrient loading, denitrification requires a supply of organic matter as energy source (Seitzinger and Nixon, 1985 and its references), resulting in anaerobic respiratory processes (Korom, 1992), which may conversely promote sediment denitrification (Baker et al, 2000;Zhang et al, 2012 and its references). Nutrients absorption of seagrass roots may impact on uptake of seagrass leaves to nitrogen Harlin, 1982, 1984).…”