Nitrogen interception and export by experimental salt marsh plots exposed to chronic nutrient addition

Marine Ecology Progress Series

Dale Goehringer¹  Brian Howes¹  Lindsay D. Brin¹  Ivan Valiela¹ 

关键词: Spartina salt marsh;    New England;    Nutrient addition;    Nitrogen export;    Nitrogen uptake;    Dissolved inorganic nitrogen;    Dissolved organic nitrogen;    Nitrate;    Ammonium;   

DOI  :  10.3354/meps08460

学科分类：海洋学与技术

来源: Inter-Research

【 摘 要 】

ABSTRACT: Mass balance studies conducted in the 1970s in Great Sippewissett Salt Marsh, New England, showed that fertilized plots intercepted 60 to 80% of the nitrogen (N) applied at several treatment levels every year from April to October, where interception mechanisms include plant uptake, denitrification and burial. These results pointed out that salt marshes are able to intercept land-derived N that could otherwise cause eutrophication in coastal waters. To determine the long-term N interception capacity of salt marshes and to assess the effect of different levels of N input, we measured nitrogenous materials in tidal water entering and leaving Great Sippewissett experimental plots in the 2007 growing season. Our results, from sampling over both full tidal cycles and more intensively sampled ebb tides, indicate high interception of externally added N. Tidal export of dissolved inorganic N (DIN) was small, although it increased with tide height and at high N input rates. NH₄⁺ export was generally 2 to 3 times NO₃^– export, except at the highest N addition, where DIN export was evenly partitioned between NO₃^– and NH₄⁺. Exports of dissolved organic N were not enhanced by N addition. Overall, export of added N was very small, <7% for all treatments, which is less than earlier estimates. Apparent enhanced tidal export of N from N-amended plots ceased when N additions ended in the fall. Nitrogen cycling within the vegetated marsh appears to limit N export, such that interception of added N remains high even after over 3 decades of external N inputs.

【 授权许可】

Unknown