Fluxes of methane and distribution of sulfate as influenced by coastal salt-marsh soil ecosystem of Northern Germany

Abstract

The study was conducted in Schleswig-Holstein at the Wadden sea coast of Northern Germany to evaluate the possible factors controlling methane (CH 4 ) and sulfate (SO 4 ) dynamics along a toposequence of daily to seasonally flooded coastal salt marsh soils. The soil at the top end of the salt marsh (with a height of 1.8 m above sea level: a.s.l. and a dense vegetation cover) was salic silty to clayic Typic Sulfaquent, while the soil at the bottom end (with some salt bushes and a 1.4 m a.s.l.) was sandy to silty Haplic Sulfaquent. The mean (depth: 0-100 cm) values of pH were around 7, and of redox potentials in the Typic Sulfaquent were ranged from -162 to +104 mV during all the seasons. The annual average emissions of CH 4 were almost 10 fold higher (0.3 g m -2 a -1 ) in Haplic Sulfaquent than that (0.03 g m -2 a -1 ) of the Typic Sulfaquent. In all the profiles, the concentrations of CH 4 were very low and varied significantly (p≥0.05) with the seasons and soil depths. The concentrations of CH 4 showed no dependence to temperature. The SO 4 contents were observed maximum in the Typic Sulfaquent followed by Haplic Sulfaquent during all the seasons. There is no noticeable correlation was obtained between the SO