• 研究论文 •

### 深水湖泊沉积物不同形态氮的生物地球化学特征——以百花湖为例

1. (1天津大学表层地球系统科学研究院， 天津 300072；2University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom；3中国科学院地球化学研究所环境地球化学国家重点实验室， 贵阳 550081；4贵州大学国土资源部喀斯特环境与地质灾害重点实验室， 贵阳 550025）
• 出版日期:2018-03-10 发布日期:2018-03-10

### Biogeochemical characteristics of nitrogenous species in sediments of Baihua Lake.

SI Xia-li1, YUE Fu-jun2*, WANG Zhong-Jun3, ZENG Jie3,4, JIA Guo-dong1, ZHONG Jun1, LI Si-liang1

1. (1Institute of SurfaceEarth System Science, Tianjin University, Tianjin 300072, China;  2University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom; 3 Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; 4Key Laboratory of Karst Environment and Geohazard, Ministry of Land and Resources, Guizhou University, Guiyang 550025, China).
• Online:2018-03-10 Published:2018-03-10

Abstract: Deep lakes experience alternate oxidation and reduction environment, which mayaffect the biogeochemical processes of nitrogen. Lake sediments generally have a unique reduction environment with complicated biogeochemical processes of nitrogen. In the present study, vertical sediments were collected from a typical plateau deep lake, Baihua Lake, during summer stratification. The concentration of nitrogenous species in pore water, watersoluble, adsorptionsoluble, and particle organic nitrogen (PON) with δ15NPON in the different depths of sediments were analyzed. The results showed that the concentration of total nitrogen (TN) in the pore water,ranging from 6.9 to 42.8 mg·L-1, was mainly composed of NH4+-N, ranging from 6.6 to 25.6 mg·L-1, and dissolved organic nitrogen. The concentrations of nitrate and nitrite were underdetection line, indicating that the nitrate was used by denitrification or the potential dissimilatory reduction. The concentration of adsorptionsoluble NH4+-N was higher than that of watersoluble NH4+-N. The concentration of PON in the sediment ranged from 0.22% to 0.60%. Meanwhile, its variation tendency was well fit to the exponential decay pattern, suggesting that the variation of PON concentration in the sediment may be due to the diagenetic effect and mineralization. The δ15NPON value above 31 cm depth decreased with depth, ranging from 3.4‰ to 10.0‰ and with an average of 6.4‰. It showed a more decrease tendency above 10 cm depth, which may be caused by the microbial degradation activity and the water exchange between pore water and lake water. The trend of δ15NPON value below 31 cm depth was opposite to that of the surface, which may be the result of diagenesis at early stage. TN in pore water had higher δ15N value than did watersoluble and adsorptionsoluble N. TN in watersoluble and adsorptionsoluble N had similar δ15N value, which was higher than the δ15NPON. The results suggested that the increases of NH4+-N concentration in pore water may be related to the dissimilatory reduction process.