Abstract: Acid mine drainage (AMD) production during mining industry has the characteristics of extensive pollution, long duration, and serious harm. Biooxidation of pyrite is the main cause of AMD. Exploring the details of pyrite bio-oxidation is of great significance to understand the pattern of AMD production under natural conditions. In this study, shaking flask experiments were carried out to investigate the effects of temperature (10-30 ℃) and pyrite slurry concentration (0.67%-2%) on pyrite biooxidation process. The results showed that bio-oxidation of 1 g pyrite for 18 days released 0.6 mmol, 64.53 mg, and 151.0 mg of H⁺, total Fe and SO₄^2-, respectively at 30 ℃ with pyrite slurry concentration of 2%. Compared with the pyrite slurry concentration of 2%, the amount of released H⁺ and total Fe in pyrite bio-oxidation systems decreased by 13.3% and 18.2% respectively when the pyrite slurry concentration was reduced to 0.67%. Compared with temperature 30 ℃, when temperature was decreased to 10 ℃, the amount of released H⁺ and total Fe in pyrite bio-oxidation systems decreased by 80.0% and 82.6%, respectively. The SO₄^2- concentration showed a distinct increasing trend in pyrite bio-oxidation system under high pyrite slurry concentration (1%-2%) and high temperature (20-30 ℃), whereas the SO₄^2- concentration did not change under low pyrite slurry concentration (0.67%) and low temperature (10 ℃). Biooxidized pyrite surface showed erosion pits with different densities according to the bio-oxidation degree under different treatments. In addition, secondary iron minerals covered the bio-oxidized pyrite obviously when the pyrite biooxidation was at 30 ℃. Our results provide supports for further understanding the formation mechanism of AMD.

Key words: water use efficiency., spring maize, water consumption characteristics, yield, alternate subsurface drip irrigation