A time series of hydroxylamine (NH₂OH) in the southwestern Baltic Sea

Abstract

[1] Hydroxylamine (NH 2 OH) is an intermediate of the marine nitrogen cycle and in marine environments dissolved NH 2 OH is short-lived. In order to investigate the distribution of NH 2 OH under varying oxygen conditions, its seasonal variability was investigated on a monthly basis from July 2005 to May 2006 at the time series station Boknis Eck located in the Eckernförde Bay (southwestern Baltic Sea). NH 2 OH concentrations were generally low and close to the detection limit. However, a pronounced increase was observed after the seasonal thermohaline stratification period with low oxygen/anoxic conditions in the deep layers was terminated in November 2005. The increase of NH 2 OH was associated with the re-oxygenation of the water column. We conclude that NH 2 OH was produced in-situ during nitrification. We suggest that the detection of significant amounts of NH 2 OH can be used as an indicator for a ''fresh'' nitrifying system. Citation: Schweiger, B., H. P.Hansen, and H. W. Bange (2007), A time series of hydroxylamine (NH 2

Marine hypoxia/anoxia as a source of CH<sub>4</sub> and N<sub>2</sub>O

“…Gulf of Mexico, East China Sea, eastern Arabian Sea and northern Bay of Bengal), CH 4 concentrations are also enhanced by riverine inputs. Another complexity arises from in situ production of CH 4 in the water column itself, for which there is considerable circumstantial evidence (Scranton and Brewer, 1977;Farrington, 1977: Karl andTilbrook, 1994;Kelley, 2003;Karl et al, 2008). This is reflected by significant supersaturation in surface water in productive margins that experience upwelling but no hypoxia (e.g.…”

“…For example, it has been speculated that production within anoxic environments, most probably within guts of zooplankton, accounts for the maximum (Oremland, 1979;Reeburgh, 2007, and references therein). Coastal waters may also contain elevated CH 4 concentrations due to supply from marshlands/estuaries (Scranton and McShane, 1991;Bange et al, 1994;Jayakumar et al, 2001;Bange, 2006b) and from sediments, particularly in areas of hydrocarbon seepage or hydrate destabilization, resulting in pronounced subsurface maxima extending offshore from the continental margin that are distinct from the mixed layer maximum mentioned above (e.g., Scranton and Brewer, 1977;Brooks et al, 1981;Cynar and Yayanos, 1991;Ward, 1992;Tilbrook and Karl, 1995). More recently, it has been shown that CH 4 may be produced aerobically through decomposition of methylphosphonate that may serve as a source of phosphorus in phosphatepoor environments such as tropical surface waters (Karl et al, 2008).…”

“…At the Boknis Eck Time Series Station (Eckernförde Bay, SW Baltic Sea), N 2 O has been measured on a monthly basis since July 2005 (Schweiger, 2006;Bergmann, 2009 (Schweiger et al, 2007).…”

Water column biogeochemistry of oxygen minimum zones in the eastern tropical North Atlantic and eastern tropical South Pacific oceans

“…This implies that significant pulses of N 2 O emissions to the atmosphere occur only when a shallow coastal system rapidly shifts from oxic to anoxic/sulfidic conditions and vice versa . This can be explained by a lag of N 2 O reduction by denitrifiers when they switch from oxygen to nitrogen respiration (Codispoti, 2010) or N 2 O production during the reestablishment of nitrification after O 2 ventilation (Schweiger et al, 2007). CH 4 production is also tightly connected to OMZs (see overview in Naqvi et al, 2010).…”

Summer upwelling at the Boknis Eck time-series station (1982 to 2012) – a combined glider and wind data analysis

“…Schweiger et al, 2007;Dale et al, 2011;Bange et al, 2011;Bertics et al, 2013;Dähnke and Thamdrup, 2013). Variability from seasonal to long term have been described for a number of parameters sampled at BE (e.g.…”