数字表达规范。句首数字用英文；文中数字小于等于10的用英文、大于10的用阿拉伯数字，但带单位的和同一意群中的一律用阿拉伯数字（如3 g, 12 m; 6, 14, 20 cells/L; 4.28×105 - 5.17×106 cells/L; 3 orders, 6 families, 20 genera, 130 species）。
Eutrophication Assessment and Analysis of Nutrient Loading in Hanfeng Lake
ZHENG Zhi-wei, HU Lian, ZOU Xi, PAN Xiao-jie, ZHANG Zhi-yong, WAN Cheng-yan
（Key Laboratory of Ecological Impacts of Hydraulic-Projects and Restoration of Aquatic Ecosystem of Ministry of Water Resources, Institute of Hydroecology, Ministry of Water Resources and Chinese Academy of Sciences, Wuhan, 430079）
Abstract: Eutrophication, a serious water quality problem, has been receiving increased national and international attention. Nitrogen and phosphorous are the primary nutrients leading to eutrophication in lakes and reservoirs and, the established management goals for water quality provide impetus for the control of eutrophication. Therefore, the evaluation of eutrophication and the analysis of water resource capacity have gradually become important means for managing water resources. In 2012 and 2013, seasonal monitoring of physical and chemical parameters in the Hanfeng Lake was carried out and parameters included total nitrogen (TN), ammonia nitrogen (NH3-N), total phosphorous (TP), transparency (SD), chemical oxygen demand (CODMn) and chlorophyll a（chl-a）. Samples were collected at 10 sites, located in the Nanhe area (HF1-HF4), Donghe area（HF5-HF6）and the main stem of Xiaojiang (HF7-HF10), respectively. Monitoring data during March, June, September and December of the two years were collected. A comprehensive eutrophic state index was applied to assess the trophic status, and the Vollenweider-Dillon model was used to analyze the nutrient loading and assimilation capacity of Hanfeng Lake. Results show that the water quality of Hanfeng Lake met water quality standards II-V for surface water. The mean values (range in parentheses) for TN, NH3-N, TP, CODMn were 1.41 mg/L (0.76-2.24 mg/L), 0.41 mg/L (0.17- 0.95 mg/L), 0.069 mg/L (0.01-0.106 mg/L), and 4.22 mg/L (2.34-14.6 mg/L), respectively. Water quality in the Donghe area was better than in Xiaojiang and the Nanhe area, with the pollution level lowest in autumn for all three areas. In general, Hanfeng Lake is mesotrophic to slightly eutrophic, with higher nutrient levels in the Nanhe area. Total nitrogen levels were particularly high and, as a single indicator, were always in the eutrophic range, from slight, to moderate and even severe. Analysis showed that loading of CODMn, total nitrogen and total phosphorus in Hanfeng lake were 37335 t/a, 1643.8 t/a and 109.1 t/a, respectively. Nutrient loading should be reduced by 36% for nitrogen and by 58% for phosphorus to achieve water quality meeting Level II standards throughout Hanfeng Lake.
Key words: Hanfeng Lake; eutrophication; comprehensive assessment; nutrient loading