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引用本文:陈国元,李建秋,李清曼,周易勇.武汉月湖沉积物不同形态氮含量与转换途径的垂直变化.湖泊科学,2008,20(4):463-469. DOI:10.18307/2008.0409
CHEN Guo-yuan,LI Jian-qiu,LI Qing-man,ZHOU Yi-yong.Different forms of nitrogen contents and their vertical variations of transformation modes of the sediments of Lake Yuehu, Wuhan. J. Lake Sci.2008,20(4):463-469. DOI:10.18307/2008.0409
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武汉月湖沉积物不同形态氮含量与转换途径的垂直变化
陈国元1,2, 李建秋1, 李清曼1, 周易勇1
1.中国科学院水生生物研究所, 武汉 430072;2.中国科学院研究生院, 北京 100049
摘要:
描述了2005年6月月湖4个采样点沉积物不同形态氮含量、净硝化速率、净氮矿化速率与硝酸还原酶活性的垂直分布.亚表层(5-10cm)交换态NO3--N含量最高,而有效态氮与交换态NH4+-N含量最低,故具临界意义.有效态氮多以交换态NH4+-N的形式贮存于表层(0-5cm)与底层(>10cm),且底层含量较高,这种分布与缺氧状态有关.表层沉积物总氮和有机态氮含量、净硝化速率、净氮矿化速率与硝酸还原酶活性均高,间隙水中NH4+-N浓度亦取峰值,而溶解态NO3--N浓度最低,据此提出氮循环的基本过程:有机态氮经矿化与硝化产生NH4+-N与NO3--N,同时导致有利于NH4+-N生成的缺氧状态,并促使部分NO3--N异化还原为NH4+-N,二者共同构成表层间隙水中丰富的NH4+-N源.总之,富营养化湖泊表层沉积物富含有机态氮,故为氮生物地球化学循环的最为活跃的层面,而NH4+-N则为最具有效性且含量最高的形态.
关键词:  月湖  沉积物  氮含量  转换途径  垂直变化
DOI:10.18307/2008.0409
分类号:
基金项目:中国科学院知识创新工程重要方向项目(KZCX2-YW-426);国家自然科学基金重点项目(40730528)联合资助
Different forms of nitrogen contents and their vertical variations of transformation modes of the sediments of Lake Yuehu, Wuhan
CHEN Guo-yuan1,2, LI Jian-qiu1, LI Qing-man1, ZHOU Yi-yong1
1.Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, P.R.China;2.Graduate School of Chinese Academy of Sciences, Beijing 100049, P.R.China
Abstract:
Vertical distributions of nitrogen contents, net nitrification rates, net N-mineralization rates and nitrate reductase activities in sediments of Lake Yuehu in June, 2005, were described on basis of four samples from the lake. The results showed that there was a critical layer in which exchangeable nitrate contents were the highest. Exchangeable ammonium and available nitrogen contents were the lowest in the subsurface sediment (5-10cm). Available nitrogen was stored mainly in the form of exchangeable ammonium in both surface (0-5cm deep) and deeper layers (>10cm deep) where their contents were higher. The pattern of this distribution can be explained by anaerobic conditions. The surface sediment not only showed higher contents of total nitrogen and organic nitrogen, rates of net nitrification, N-mineralization and nitrate reductase activities, but also displayed the highest ammonium and the lowest nitrate concentrations in interstitial water. Therefore, based on a nitrogen cycling mode, we proposed that organic nitrogen was re-mineralized to ammonium and nitrate with processes of the former being nitrified into the later, resulting in anaerobic conditions that contributed to ammonium accumulation by the production of its own and nitrate reduction in interstitial water of surface sediment. In general, the surface sediment in eutrophic lakes, enriched by organic nitrogen, is the most active dimension for the biogeochemical cycling of nitrogen with ammonium being the major and most effective forms.
Key words:  Lake Yuehu  sediment  nitrogen contents  transformation modes  vertical variations
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