In:
Biogeosciences, Copernicus GmbH, Vol. 16, No. 20 ( 2019-10-25), p. 4097-4111
Abstract:
Abstract. Nitrous oxide (N2O) is a potent greenhouse gas, and it is
involved in stratospheric ozone depletion. Its oceanic production is mainly
influenced by dissolved nutrient and oxygen (O2) concentrations in the
water column. Here we examined the seasonal and annual variations in
dissolved N2O at the Boknis Eck (BE) Time Series Station located in
Eckernförde Bay (southwestern Baltic Sea). Monthly measurements of
N2O started in July 2005. We found a pronounced seasonal pattern for
N2O with high concentrations (supersaturations) in winter and early spring
and low concentrations (undersaturations) in autumn when hypoxic or anoxic
conditions prevail. Unusually low N2O concentrations were observed
during October 2016–April 2017, which was presumably a result of prolonged
anoxia and the subsequent nutrient deficiency. Unusually high N2O
concentrations were found in November 2017 and this event was linked to the
occurrence of upwelling which interrupted N2O consumption via
denitrification and potentially promoted ammonium oxidation (nitrification)
at the oxic–anoxic interface. Nutrient concentrations (such as nitrate,
nitrite and phosphate) at BE have been decreasing since the 1980s, but oxygen
concentrations in the water column are still decreasing. Our results
indicate a close coupling of N2O anomalies to O2 concentration,
nutrients, and stratification. Given the long-term trends of declining
nutrient and oxygen concentrations at BE, a decrease in N2O
concentration, and thus emissions, seems likely due to an increasing number
of events with low N2O concentrations.
Type of Medium:
Online Resource
ISSN:
1726-4189
DOI:
10.5194/bg-16-4097-2019
DOI:
10.5194/bg-16-4097-2019-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2019
detail.hit.zdb_id:
2158181-2
