入洱海河流临湖段底泥氮的分布

于2013年7月在洱海流域采集了17条主要入洱海河流临湖段的底泥和上覆水样品,测定分析样品中TN、NH₃-N和NO₃--N的含量,揭示底泥中氮素的分布特征,并探讨底泥与上覆水中氮素含量的相关性. 结果表明:①17条入洱海河流临湖段底泥中w(TN)为23.10～310.60 mg/kg,平均值为141.66 mg/kg. ②对w(TN)有显著性差异的河流进行分组,并按照w(TN)由低到高排序为清碧溪、双鸳溪<白石溪<灵泉溪、龙溪、阳溪<桃溪、梅溪、隐仙溪、弥苴河<莫残溪、波罗江<永安江<锦溪<中和溪、罗时江、白鹤溪. 其中,各组之内河流间w(TN)无显著差异,而各组之间w(TN)差异显著(P=0.05). ③底泥中w(NH₃-N)、w(ON)与w(TN)呈极显著正相关,氮存在形态以ON为主. 其中,“北三江”临湖段底泥的厌/缺氧程度高,底泥中w(NO₃--N)占w(TN)的比例明显低于西部入洱海河流；上覆水中ρ(TN)与底泥中w(TN)、w(ON)呈极显著正相关. 

Characteristics of Nitrogen Distribution in Sediments of Inflow Rivers of Erhai Lake, China

Sediments and overlying water from a total of 17 main inflow rivers of Erhai Lake were sampled in July 2013. The contents of total nitrogen (TN), ammonia nitrogen (NH₃-N) and nitrate nitrogen (NO₃--N) were measured, and the nitrogen distribution in the sediments and its correlation with the overlying water was analyzed. The aim of the study was to provide basic information for pollution abatement and the establishment of a buffer zone for Erhai Lake. The results showed that the TN contents of the sediments varied from 23.10 to 310.60 mg/kg, with an average of 141.66 mg/kg. The inflow rivers varied significantly in terms of TN contents, and could be divided into several groups, including Qingbixi River and Shuangyuanxi River; Baishixi River; Lingquanxi River, Longxi River and Yangxi River; Taoxi River, Meixi River, Yinxianxi River and Mijuhe River; Mocanxi River and Boluojiang River; Yonganjiang River; Jinxi River; and Zhonghexi River, Luoshijiang River and Baihexi River. The inflow rivers within each group were not significantly different between each other, while the rivers among groups were significantly different (P=0.05). In the sediments, the organic nitrogen (ON) was a fundamental state of nitrogen in the sediments, and the contents of NH₃-N and ON were both significantly positively correlated with TN contents. Furthermore, the proportion of NH₃-N contents to TN contents in the three northern rivers, namely Yonganjiang River, Mijuhe River and Luoshijiang River, were obviously lower than those in the western rivers, which was attributed to the high degree of anaerobic/anoxic of the surface sediments. The TN contents in the overlying water showed a significantly positive correlation with the contents of TN and ON in the sediments.