POLLUTION SITUATION OF ABANDONED OXIDATION PONDS

Biomonitoring and evaluation were performed for abandoned oxidation ponds in the Ya-Er Lake, based on the National Standard of PRC "Water Quality-Microbial Community Biomonitoring PFU Method". During this investigation, altogether 192 species of protozoa were identified and recorded, including 48 phytomastigophora species, 46 zoomastigophora species, 82 ciliata species and 16 sarcodina species. The biological parameters, that is, the structural and functional parameters of PFU protozoan community, resulted from this study demonstrated that the first oxidation pond at present changed greatly compared with that in 1982 and the second oxidation pond changed too, but not as much as the first pond. The other three ponds became better in the following sequence: pond III, pond Ⅳ, pond Ⅴ during the first study, and the sequence: pond Ⅴ, pond III, pond Ⅳ during the second study. But the differences among the three ponds were not significant. The comparison of the results from the present study and that in 1982 demonstrated that the water quality and aquatic ecology became better after the oxidation ponds were abandoned. Fig 5, Tab 3, Ref 13