Seasonal variability of benthic ammonium release in the surface sediments of the Gulf of Gdansk (southern Baltic Sea)

Oceanologia

关键词: Ammonium;    Benthic fluxes;    Eh;    Sediments;    Southern Baltic Sea;   

DOI  :  

来源: DOAJ

【 摘 要 】

This paper describes the seasonal and spatial variations of diffusive sediment-water ammonium fluxes in the western part of the Gulf of Gdansk (southernBaltic). It assesses the potential environmental controls of these fluxes, suchas the inflow of organic matter to bottom sediments and its quality,temperature-induced degradation of organic matter, and the redox potential ofsediments. Ammonium fluxes, calculated using Fick's first law, were always inthe direction from the sediment into the water column and differed significantlywith respect to sediment type. Fluxes were most intensive in sediments with thehighest silt-clay fraction located in the deepest parts of the study area. Themean annual diffusive fluxes of ammonium from sediments to near-bottom waterwere estimated at 5.24 tonnes km^-2 year^-1 for silty-clays, 1.85 tonnes km^-2 year^-1 for silty-sands and 1.03 tonnes km^-2 year^-1 for sandysediments. There was a high seasonal variation, with the greatest ammoniumrelease in summer and early autumn, when the temperature of near-bottom waterwas the highest. On the basis of the calculated diffusive ammonium fluxes, weestimated that approximately 2700 tonnes of N-NH₄⁺ are released annually from the surface sediments of the western part of the Gulf of Gdansk, providinga minimum of 10% of the mineral nitrogen essential for primary production insurface waters. Our results are undoubtedly underestimated, as we disregardedadvective ammonium fluxes, which in some areas of the Gulf of Gdansk could wellbe comparable to diffusive fluxes.

【 授权许可】

Unknown