کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
9758412 1496748 2005 21 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Nitrogen removal in marine environments: recent findings and future research challenges
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی (عمومی)
پیش نمایش صفحه اول مقاله
Nitrogen removal in marine environments: recent findings and future research challenges
چکیده انگلیسی
Respiratory reduction of nitrate (denitrification) is recognized as the most important process converting biologically available (fixed) nitrogen to N2. In current N cycle models, a major proportion of global marine denitrification (50-70%) is assumed to take place on the sea floor, particularly in organic rich continental margin sediments. Recent observations indicate that present conceptual views of denitrification and pathways of nitrate reduction and N2 formation are incomplete. Alternative N cycle pathways, particularly in sediments, include anaerobic ammonium oxidation to nitrite, nitrate and N2 by Mn-oxides, and anaerobic ammonium oxidation coupled to nitrite reduction and subsequent N2 mobilization. The discovery of new links and feedback mechanisms between the redox cycles of, e.g., C, N, S, Mn and Fe casts doubt on the present general understanding of the global N cycle. Recent models of the oceanic N budget indicate that total inputs are significantly smaller than estimated fixed N removal. The occurrence of alternative N reaction pathways further exacerbates the apparent imbalance as they introduce additional routes of N removal. In this contribution, we give a brief historical background of the conceptual understanding of N cycling in marine ecosystems, emphasizing pathways of aerobic and anaerobic N mineralization in marine sediments, and the implications of recently recognized metabolic pathways for N removal in marine environments.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Marine Chemistry - Volume 94, Issues 1–4, 1 March 2005, Pages 125-145
نویسندگان
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