| Summary: | 碩士 === 國立清華大學 === 生命科學系 === 93 === Aquatic Organisms environment Diagnostics (AOD) is used in this research for estimating the water self-purification influence of stream.
Our data shows that AOD can reflect the water quality faithfully and is a better method than other water quality indices to tell the minor differences between samples. According to the fish fauna and the AOD results in Ke-tzu-hu stream, a branch of Touchien River, Hsien-chu, Rhinogobius rubromaculatus is suggested to be used as the slight-pollution level index of water quality.
According to the AOD results, the water self-purification influences occur most significant between Site 5 and Site 6, and Site 7 and Site 8 in midstream and downstream of Ke-tzu-hu stream. The pollution sources mostly come from two canals at the sections between Site 2 and Site 3, and between Site 6 and Site 7. The efficiency of self-purification based on AOD value of fish is 0.511~0.578 (% / m2 ), and the efficiency of self-purification based on AOD value of shrimp is 0.506~0.578 (% / m2 ) between Site 5 and Site 6. The efficiency of self-purification based on AOD value of fish is 0.12~0.26 (% / m2 ), and the efficiency of self-purification based on AOD value of shrimp is 0.198~0.278 (% / m2 ) between Site 7 and Site 8. The difference in these two sections of self-purification efficiency may be the efficiency of self-purification have been reach test limit in shorter than 0.5 km.
Water shore plan of Ke-tzu-hu stream was proceeded in 2003 from Site 3 to Site 8, the stream width was designed as 6m with ecological network protection along two shores, and the riverbed was covered by networks made of coconut palms. When the flow is over 0.38 CMS, AOD value of Site 3, the most polluted site, will reach 1800%. Under this condition, the guan-dong bridge area discharged sewage will be clear up by dilution influence.
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