DEVELOPMENT AND TESTING OF A DIATOM-BASED INDEX OF BIOTIC INTEGRITY FOR RIVER ECOSYSTEMS IMPACTED BY ACID MINE DRAINAGE IN GAOLAN RIVER, CHINA

摘要

Acid mine drainage (AMID) characterized by low pH, high concentrations of dissolved metals and metal oxide deposits affects aquatic ecosystems severely. However, the quantitative impacts of AMID on lotic ecosystem, especially the seasonal variation of impacts, are still unclear. We developed a diatom-based index of biotic integrity (AMD-DIBI) to evaluate AMID impairment on Gaolan River. Pollution Tolerance Index (PTI), % No. of Cocconeis species, % No. of Pinnularia species, No. of Cymbella species, relative abundance of prostrate diatoms, and relative abundance of Achnanthes were selected to build AMID-DIBI. AMD-DIBI scores between reference and impaired sites displayed significant differences. On the basis of AMID-DEBI scores, the ecological conditions of most reference sites were "excellent" or "good", while the impaired sites were "Poor" or "Moderate". AMID impairments were more severe in dry season than that in wet season: about 20km lower reach were impaired in wet season, while 50km at least in dry season. AMD-DIBI is meaningful to assess the ecological conditions, quantify impairment of AMID and measure the effectiveness of restoration.