三峡库区香溪河水体营养状态变化分析

为了系统了解三峡水库175 m蓄水运行后坝前最大支流香溪河水体营养状态变化,为水库水环境管理提供技术支撑,利用2011~2016年香溪河水体营养状态指标长系列的野外观测资料,分析了香溪河营养状态相关指标叶绿素a、总磷、总氮、透明度、高锰酸盐指数及综合营养状态指数动态变化。结果表明:香溪河水体综合营养状态指数年内呈先增大后减小的变化过程,最大值出现在每年4~9月间,最小值通常出现在水库高水位运行期11月至次年1月,2011~2016年,年均水体综合营养状态指数总体较为稳定,除2014年呈轻度富营养状态外,其他年份均为中营养状态,变化范围为45.57~52.62;香溪河水体氮磷营养丰富,年均值变化范围分别为1.41~2.06,0.13~0.20 mg/L,远高于国际上水体富营养化TN、TP浓度阈值;2011~2016年,总磷浓度年均值变化不大,总体有增大的趋势,需要引起关注;叶绿素a、透明度、高锰酸盐指数年际间总体变化不大。

Analysis on variation of nutritional status of Xiangxi River in Three Gorges Reservoir

In order to understand the nutritional status variation of the Xiangxi River, the largest tributary in the front of Three Gorges Reservoir (TGR) after 175 m impoundment, and provide technical support for the reservoir water environment management, by using the long series of field measured data from 2011 to 2016, the dynamical variations of some eutrophication indicators, such as Chl-a, TP, TN, SD, CODMn, comprehensive nutritional status (TLI) are studied. The results show that TLI of the Xiangxi River displays a tendency of increasing first and then decreasing during a year, in which the maximum value appears from April to September and the minimum value appears in the period of high water level of TGP, from November to January of the next year. In general, the annual TLI is stable in mesotrophic status, except for the year 2014 whose eutrophic status is light with TLI ranging from 45.57 to 52.62, the eutrophic status of the other years are moderate. The annual average TN and TP vary respectively in concentration from 1.41 to 2.06 mg/L and from 0.13 to 0.2 mg/L, far higher than the international threshold values for eutrophication. The average annual TP concentration change little but display a rising tendency, which needs attention. The inter-annual Chl-a, SD and CODMn change little in general.