Caetano M.,IPIMAR INRB National Institute of Biological Resources |
Bernardez P.,CSIC - Institute of Marine Research |
Santos-Echeandia J.,IPIMAR INRB National Institute of Biological Resources |
Santos-Echeandia J.,CSIC - Institute of Marine Research |
And 2 more authors.
Environmental Monitoring and Assessment | Year: 2012
Short-sediment cores and flooding water were collected at 0, 5, 15, 25 and 50 min of tidal inundation in the two sites colonised by pure stands of Spartina maritima (low marsh) and Sarcocornia fruticosa (high marsh) from the Rosário salt marsh (Tagus estuary, SW Europe). Concentrations of NH 4 +, NO 3 - +NO 2 - and HPO 4 2-, Fe and Mn were measured in tidal flooding water and pore water. Flooding water is enriched in nutrients, particularly ammonium due to local discharge of untreated urban effluents. Nevertheless, NH 4 + and NO 3 - +NO 2 - concentrations in flooding waters at t=5 min (NH 4 + =246±7 μM, NO 3 - +NO 2 - =138±1 μM for S. fruticosa and NH 4 + =256±8 μM, NO 3 - +NO 2 - =138±1 μM for S. maritima) rose sharply at both vegetated sites. An increase was also registered for HPO 4 2- and total dissolved Fe although the subsequent decrease was smoother. Advective transport induced by the two daily pulses of inundation is several orders of magnitude higher than the diffusive fluxes during submerged periods. In addition, solutes are exported from the sediment with the inundation and imported in submerged periods. The exported amount of inorganic nitrogen during tidal inundation (export of 3,200 μmol Nm-2 day -1to the water column), is not counterbalanced by the sink of -290 μmol Nm-2 day-1 occurred during the submerged period. © 2011 Springer Science+Business Media B.V.