酸性硫酸鹽排水對溪流生態之影響

Impact of Acidic Sulfate Drainage on River Ecology

潘聖文(Sheng-Wen Pan)

指導教授 ： 蕭友晉

國立臺灣大學/生物資源暨農學院/生物環境系統工程學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202103218

摘要

硫是生物及環境最重要的元素之一，在生物體內強化細胞排出毒素，加強抵抗力；在自然界中也負責調節環境能量循環的氧化還原過程。全球大部分的硫元素都是以化合物的型態儲存在地層中，然而人為過度開發容易造成大量硫化物溶於水加速氧化；使得流域中的硫酸鹽濃度過度增加、水質變酸的問題產生，同時在無形中也影響水生生物，這些現象統稱硫酸鹽排水。
本研究旨在於探討硫酸鹽排水對溪流生態的影響，針對長期排入硫酸鹽溫泉的八仙圳及南磺溪流域進行為期一年的水質分析及物種調查，並與未受排水影響的松溪流域比較之差異。分析結果顯示八仙圳因上游流域大量稀釋，水質不受硫酸鹽排水影響；南磺溪則受影響程度較大，解離的硫酸鹽濃度為松溪流域的七倍之多；其他水質檢測結果也顯示南磺溪水體呈現明顯酸化(pH4.9±1.2)，部分流域水溫高於周圍環境5-10℃且導電度也都有顯著升高的現象。由於南磺溪水質嚴重受損，連帶造成物種組成之改變，流域僅剩高耐受污染的水棲昆蟲(如:搖蚊科)，其餘魚、蝦、貝、蟹類物種幾乎消失。根據香農及辛普森多樣性指數分析顯示松溪流域多樣性程度高、物種個體數分布也較為均勻，皆由高敏感度的生物及原生種組成，營養階層關係錯綜複雜；八仙圳流域環境受人為干擾，高階魚類物種組成改由外來種取代(如:吳郭魚)；南磺溪多樣性程度則為最低，且物種個體數差異大；科級生物指標(FBI)及生物監測工作組平均得分(ASPT)針對南磺溪的水棲昆蟲組成進行流域健康程度評估，結果也均顯示為污染至嚴重污染等級；生物整合指標(IBI)則因南磺溪魚類物種消失導致數據過低而無法計算。藉由各項物種生態指標評估結果可知硫酸鹽溫泉排水不只對水質產生強烈影響，同時也對物種組成造成相當的危害。

關鍵字

野外採樣 ； 營養階層 ； 溪流生態系統 ； 物種生態指標 ； 硫酸鹽溫泉排水

並列摘要

Sulfur is one of the most important elements in biology and the environment. It strengthens cells in the body to excrete toxins and strengthens resistance; in nature, it is also responsible for regulating the redox process of biogeochemical cycle. Most of the sulfur in the world is stored in the stratum in the form of compounds, and these sulfides are oxidized and dissociated sulfate (SO42-) for biological absorption. However, human over-exploitation can easily cause a large amount of sulfide to dissolve in water to accelerate oxidation; the problem of excessive increase of sulfate concentration in rivers and acidic water quality occurs, and it also affects aquatic organisms invisibly, these phenomena are collectively referred to as sulfate drainage.
The purpose of this research explore the impact of sulfate drainage on the stream ecology. A year water quality analysis and species survey were conducted for the Baxian channel and Southern Sulfur Creek drainage that have been discharged into the sulfate springs for a long time, and the differences were compared with the Songxi river that were not affected by drainage. The analysis results showed that the water quality of Baxian channel is not affected by sulfate drainage due to the large amount of dilution in the upstream watershed; Southern Sulfur Creek is more affected, and the concentration of sulfate dissociated in Southern Sulfur creek was seven times that of Songxi river; according to other water quality analysis results, it also showed that the water of Southern Sulfur creek was obviously acidified (pH 4.9±1.2), and the water temperature of some river basins was higher than 5-10 degrees in the surrounding environment, and the electrical conductivity conductivity had also increased significantly. Due to the severe damage to the water quality of the Southern Sulfur Creek, and consequential changes in the species composition, only highly tolerant aquatic insects (such as Chironomididae) were left; the other fish, shrimp, shellfish, and crab species were almost extinct. According to the Shannon's and Simpson’s diversity index, the diversity of Songxi river was the largest, and relatively uniform distribution of species individuals. Species were all composed of highly sensitive organisms and native species, and the relationship between trophic level was complex; the environment of Baxian channel is greatly disturbed by humans, fish populations were replaced by exotic species (such as Oreochromis niloticus); the environment of Southern Sulfur creek was the lowest diversity, and the number of species varies greatly. The Family-level Biotic Index (FBI) and Average Score Per Taxon (ASPT) were used to assess the health of the watershed in the composition of aquatic insects in Southern Sulfur creek, the results showed the most serious pollution level; and the Index of Biotic Integrity (IBI) was too low to be calculated due to the disappearance of the fish species in Southern Sulfur creek. According to the evaluation results of various species ecological indicators, it can be seen that the sulfate springs drainage not only has a strong impact on water quality, but also causes considerable harm to species composition.

並列關鍵字

Field sampling ； Trophic level ； River ecosystem ； Species ecological indicator ； Sulfate springs drainage

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