宜蘭地區湖泊優養化指標分析

The Analysis of Trophic State Indexes for the Lakes of Yilan Area

10.6665/JLYIT.2009.8.8

史健軍(Chien-Chun Shih)

優養指標 ； 卡爾森綜合指標 ； 優養 ； Trophic state index ； Carlson's index ； Eutrophication

蘭陽學報

8期（2009 / 06 / 01）

8 - 14

繁體中文

本文針對近五年(2004~2008)宜蘭縣環保局對宜蘭地區五個湖泊水質監測資料進行優養化分析，並比較不同優養化因子及指標間之差異與關聯性。研究結果顯示，以最常用的卡爾森指標判別全部五湖泊均呈優養到超優養等級，如依修正卡爾森綜合優養指標值判定則營養化程度明顯較輕。據以計算卡爾森指標之透明度、葉綠素a及總磷測值間，透明度與總磷及透明度與葉綠素a呈負相關，除翠峰湖外，總磷及葉綠素a間則呈正相關，符合卡爾森指標推導的假定，惟相關性強弱各湖泊差異頗大。五湖泊中卡爾森綜合指標與其各單項指標間關聯性分析結果顯示以TSI(Chl-a)與卡爾森綜合指標相關性最佳，TSI(TP)次之，TSI (SD)則最差。如以環保署水體分類水質標準來判斷湖泊水質良窳，則有高達96%的機率是以水中BOD為唯一水體分類之依據，與卡爾森綜合指標對優養化程度的分類主要決定因子在湖水葉綠素a與總磷濃度有異。另各湖泊內監測點之透明度、葉綠素a及總磷測值五年平均值差異檢定結果顯示，除梅花湖之三測點在總磷的測值上顯現差異外，其他各各湖泊內之監測點數據並無差異，這些測點存在之必要性及代表性需要進一步探討。

In this paper, lake water quality monitoring data for the Yilan Area from 2004 to 2008 were obtained from the EPB of the Yilan County and were analyzed for the different trophic state indexes. The comparison of these indexes was made to demonstrate their differences and relationship. Carlson's index analysis results show that trophic states of all monitored lakes are in the eutrophic to over-eutrophic classes. However the modified Carlson's index analysis results show a less severity in the trophic state of all monitored lakes. Correlation analysis for the Secchi disk value (SD), total phosphorus (TP) and Chlorophyll a (Chl-a) show SD and TP are negatively correlated. SD and Chl-a are negatively correlated as well. But TP and Chl-a are positively correlated except for data obtain from the Cueifong Lake. Basically, the relationship of SD, TP and Chl-a is agree with the hypothesis of Carlson's index. However the correlation coefficients are highly lake depended. The subindex of Carlson's index were also analyzed for their correlation with Carlson's index also. Correlation Analysis results show that TSI (Chl-a) has the best correlation with Carlson's index. TSI (SD) shows the worst correlation with Carlson's index. In comparison to Carlson's trophic classification system. Taiwan EPA's water body rating system was also applied to evaluate the lake water quality. The results show that EPA's rating system is highly BOD depended (96% data). Therefore the rating system is different to Carlson's trophic classification system. Statistical hypothesis test and ANOVA results shown that except TP monitored data from the three sampling points in the Plum Blossom Lake are different, all other monitored TP, SD and Chl-a are no different among three different sampling point for each lake. Further studies are recommended for the suitability of the current sampling points.

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