Contribution of gaseous sulphur from salt marshes to the global sulphur cycle

Abstract

Salt marshes have high rates of sulphide production due to dissimilatory sulphate reduction1,2; and because their anaerobic sediments are exposed to the atmosphere, they are thought to be important sites of biogenic sulphur emission3,4. We report here a synthesis of the results of an annual set of monthly flux measurements of hydrogen sulphide (H2S), dimethyl sulphide (DMS), carbonyl sulphide (COS), carbon disulphide (CS2) and dimethyl disulphide (DMDS) from a Spartina marsh and an adjacent tidal creek. Dimethyl sulphide and H2S were the predominant gases released from the Spartina marsh (49% and 35% of the total, respectively) while H2S was the major gas (71%) emitted from the creek site. We suggest that the short-lived sulphur gases released from marshes may have an important role in local atmospheric sulphur budgets. Globally, saline marshes may release a total of 1.7 Tg S yr−1 (1 Tg = 1012 g) into the atmosphere, which includes more than double the quantity of two important long-lived sulphur gases, COS and CS2, needed to sustain the stratospheric sulphate layer.