کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4551680 1328315 2007 16 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Seasonal variability of denitrification efficiency in northern salt marshes: An example from the St. Lawrence Estuary
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات اقیانوس شناسی
پیش نمایش صفحه اول مقاله
Seasonal variability of denitrification efficiency in northern salt marshes: An example from the St. Lawrence Estuary
چکیده انگلیسی

In coastal ecosystems, denitrification is a key process in removing excess dissolved nitrogen oxides and participating in the control of eutrophication process. Little is known about the role of salt marshes on nitrogen budgets in cold weather coastal areas. Although coastal salt marshes are important sites for organic matter degradation and nutrient regeneration, bacterial-mediated nitrogen cycling processes, such as denitrification, remain unknown in northern and sub-arctic regions, especially under winter conditions. Using labelled nitrogen (15N), denitrification rates were measured in an eastern Canadian salt marsh in August, October and December 2005. Freshly sampled undisturbed sediment cores were incubated over 8 h and maintained at their sampling temperatures to evaluate the influence of low temperatures on the denitrification rate. From 2 to 12 °C, average denitrification rate and dissolved oxygen consumption increased from 9.6 to 25.5 μmol N2 m−2 h−1 and from 1.3 to 1.8 mmol O2 m−2 h−1, respectively, with no statistical dependence of temperature (p > 0.05). Nitrification has been identified as the major nitrate source for denitrification, supplying more than 80% of the nitrate demand. Because no more than 31% of the nitrate removed by sediment is estimated to be denitrified, the presence of a major nitrate sink in sediment is suspected. Among possible nitrate consumption mechanisms, dissimilatory reduction of nitrate to ammonium, metal and organic matter oxidation processes are discussed. Providing the first measurements of denitrification rate in a St. Lawrence Estuary salt marsh, this study evidences the necessity of preserving and restoring marshes. They constitute an efficient geochemical filter against an excess of nitrate dispersion to coastal waters even under cold northern conditions.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Marine Environmental Research - Volume 63, Issue 5, June 2007, Pages 490–505
نویسندگان
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