Seasonal nutrient fluxes variability of northern salt marshes: examples from the lower St. Lawrence Estuary
| 详细信息 | 推荐本文 | |
- 作者：Patrick Poulin ; 脡milien Pelletier ; Vladimir G. Koutitonski and Urs Neumeier
- 关键词：St. Lawrence Estuary ; Salt marshes ; Nutrients fluxes ; Hydrodynamic model ; Biogeochemical processes ; Sea ice
- 刊名：Wetlands Ecology and Management
- 出版时间：December, 2009
- 出版年：2009
- 期刊代码：42_09234861
- 类别：soc
- 卷：17
- 期：6
- 页码：655-673
- 数据来源：sp
摘要
This study presents the tidal exchange of ammonium, nitrite + nitrate, phosphate and silicate between two salt marshes and adjacent estuarine waters. Marsh nutrient fluxes were evaluated for Pointe-au-P猫re and Pointe-aux-脡pinettes salt marshes, both located along the south shore of the lower St. Lawrence Estuary in Rimouski area (QC, Canada). Using nutrients field data, high precision bathymetric records and a hydrodynamic numerical model (MIKE21-NHD) forced with predicted tides, nutrients fluxes were estimated through salt marsh outlet cross-sections at four different periods of the year 2004 (March, May, July and November). Calculated marsh nutrient fluxes are discussed in relation with stream inputs, biotic and abiotic marsh processes and the incidence of sea ice cover. In both marshes, the results show the occurrence of year-round and seaward NH4 + fluxes and landward NO2 − + NO3 − fluxes (ranging from 9.06 to 30.48 mg N day−1 m−2 and from −32.07 to −9.59 mg N day−1 m−2, respectively) as well as variable PO4 3− and Si(OH)4 fluxes (ranging from −3.73 to 6.34 mg P day−1 m−2 and from −29.19 to 21.91 mg Si day−1 m−2, respectively). These results suggest that NO2 − + NO3 − input to marshes can be a significant source of NH4 + through dissimilatory nitrate reduction to ammonium (DNRA). This NH4 +, accumulating in marsh sediment rather than being removed through coupled nitrification–denitrification or biological assimilation, is exported toward estuarine waters. From average P and Si tidal fluxes analysis, both salt marshes act as a sink during high productivity period (May and July) and as a source, supplying estuarine water during low productivity period (November and March).