Abstract: Sulfate is the main component of acid mine drainage. High concentrationsulfate wastewater discharged into the environment can produce a series of pollution and ecological damages. We collected the water and sediment samples from a basin affected by acid mine drainage in a karst area of Zhijin County, Guizhou Province and investigated the migration and transformation of sulfate in the steam system. The results showed that water acidification in the study area occurred obviously. The dissolved form of sulfur in water was mainly SO₄^2-, which had obvious attenuation in the process of water migration. Meta-stable sulfur content was low in sediments, while the exchangeable sulfate (ExS) was the dominant sulfur forms, accounting for 65% of the total sulfur (TS). The content of reduced sulfur was very low in the strong oxidizing environment. The content of different forms of reduced sulfur was in order of elemental sulfur (ES) < acid volatile sulfide (AVS) < chromium reduction sulfide (CRS). SO₄^2- in water showed a positive relationship with Fe(Ⅲ). The co-precipitation of SO₄^2- and Fe(Ⅲ) into the sediment is the main cause for the reduction of SO₄^2-.

Key words: ecological sensitivity evaluation, urban development boundary, Nanchang City, CA-Markov