• Korean Journal of Ecology and Environment
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• v.45 no.3
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• pp.289-301
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• 2012

A biological assessment of water quality was made at 9 sites of the Joyang-river and inflow streams located in Jeongseon-gun Gangwon-do, from June 2008 to September 2010. The investigation consisted of physico-chemical factors, biomass, and standing crops of epilithic diatoms. In addition, the community structure of epilithic diatoms was analyzed, and the water quality was assessed using DAIpo and TDI. The pH varied from 7.4~10.2 which is attributed to the Joyang-river area consisting of limestone. A total of 117 taxonomic groups of epilithic diatoms, including: 2 orders, 6 families, 23 genera, 95 species, 15 varieties, 2 forms, and 5 unidentified species, were found in the Joyang-river. 11 taxa, including Achnanthes laterostrata and Cymbella delicatula which live in neutral to alkali pH, were found. An indicator species of alkali waters, Cymbella delicatula, was routinely observed to have a relative frequency of over 10% in I3 and I4. In the result of the biological assessment using DAIpo, the Joyang-river was rated class A, with an average of 77.03 and inflow streams were rated class B with an average of 65.84. As for the results of TDI analysis, the Joyangriver was rated class A~B, and inflow streams were rated class A~D. Accordingly, the water quality of the Joyang-river was determined to be superior to that of inflow streams. Although the main stream showed low water quality at sites J2 and J3, correlating with a reduction in the quality of inflow stream, I1 in September 2009.