The sinks of dissolved inorganic nitrogen in surface water of wetland mesocosms

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• 作者：Yuechen Tan^a ; Jing Li^a ; Jinwei Cheng^a ; Binhe Gu^b ; ; Jianming Hong^a ; ^{hjm2910@263.net}
• 关键词：Emergent plants ; Nitrogen assimilation ; Stable isotope labeling ; Submerged plants ; Wetlands
• 刊名：Ecological Engineering
• 出版年：2013
• 出版时间：March, 2013
• 年：2013
• 卷：52
• 期：Complete
• 页码：125-129
• 全文大小：316 K

文摘

The transport of dissolved inorganic nitrogen in wetlands was investigated in the Yeyahu National Preserve of Beijing, China, from July to December 2011. Stable isotope of nitrogen (¹⁵N) as NH₄⁺ was added to experimental mesocosms vegetated by seven common wetland plants. The ¹⁵N abundance in soil and various plant parts were measured at prescribed time intervals during the 49-day experimental period. Rapid ¹⁵N enrichments were found in soil and aquatic plants during the first sampling event at day 3 and typically increased linearly during the experimental period. Highest ¹⁵N enrichment was found in submerged plants, followed by emergent plants and soil. No differences in ¦Ä¹⁵N values were found among leaves and stems of all submerged plants (Potamogeton pusillus, Potamogeton perfoliatus, Najas marina, Ceratophyllum demersum), suggesting that these plant structures are equally effective in nitrogen assimilation. The roots of P. perfoliatus displayed the lowest enrichment compared to the stems and leaves. Such results indicate that submerged plant roots may have a relatively weak role in nitrogen assimilation. The two emergent plants (Phragmites australis and Typha orientalis) showed no differences in ¦Ä¹⁵N values among all plant parts, suggesting rapid translocation of nitrogen from roots to other portions. This experiment demonstrates that wetland soil and plant stems and leaves are major sinks for dissolved nitrogen from the surface water and provides valuable insight into nitrogen retention and transport pathways in various wetland plants.