洞庭湖湿地对污染物的净化功能与价值

Purification Function and Value of Dongting Lake Wetland

利用洞庭湖水文观测站、环境监测站和实地考察资料,分析洞庭湖湿地对污染物的净化功能.结果表明：每年输入湿地TN670 132.47 t、TP 41 103.85 t;输出TN 554 099.14 t、TP 34 211.93 t;贮留净化TN 116 033.27 t、TP 6 892.25 t;贮留净化率分别17.31%和16.77%;COD输入量为3 170 489.26 t,输出量为3 072 641.97 t,贮留净化量为97 847.29 t,贮留净化率3.086%;重金属元素和污染性化合物输入量为10 156.616 t,输出量为9 732.775 t,贮留净化量为423.840 t,贮留净化率4.17%;利用支出费用成本法评估的洞庭湖湿地净化污染物功能价值为57 798.352×104元,因洞庭湖为过水型湖泊,换水周期短（8-12 d）,因此该湿地对污染物的贮留净化率比一般蓄水型湖泊湿地低.

Based on the investigation data obtained from the hydrological observation station, environmental monitor station and filed examination materials, of Dongting Lake, this article analyzes the purifying functions of the lake＇s everglade. Results show that the annual input of TN to the everglade is 670 132.47 t and that of TP is 41 103.85 t; that the output of TN is 554 099.14 t and that of TP is 34 211.93 t; that the storage and purification of TN is 116 033.27 t and that of TP is 6 892.25 t, the reserved purifying ratio being 17.31% and 16.77%; that COD input is 317 849.26 t and COD output is 3 072 641.97 t, the purifying ratio being 3. 086%; and that the total input of heavy metal elements, inorganic and organic contaminations is 10 156. 616 t and the total output is 9 732. 775 t, the purifying ratio being 4.17%. By using a cost method for the assessment, the purification function of Dongting Lake wetland is worth 57 798. 352 × 10^4 yuan because it is a seasonal impounding-releasing lake, its water exchange cycle being short （8 -12 days）. Therefore, its reserved purifying ratio is lower than that of other impounding wetlands.