Dynamic changes of dissolved organic matter (DOM) from coal gangue

The filled coal gangue from the gob area of Qilanta Coal Mine,Shenhua Shendong Coal Group Corporation Limited was selected to do leaching experiments to explore the dynamic changes of DOM at room temperature. The re- sults show that the pH value of effluent samples from the gangue column decrease from 8. 74 to 7. 64. The variations of electronic conductivity (EC) and total dissolved solids (TDS) of effluent samples,which contains low levels of nitrate and ammonia nitrogen,experience three phases,namely rapidly falling,slowly falling and tending to be stable. Initially the values of DOC and UV254 in the effluent samples increase rapidly,then decrease sharply and remain stable at last. Moreover,there is a good linear correlation relationship between DOC and UV254(R2 = 0. 62),which indicates that the DOM in the studied coal gangue contains some benzene ring aromatic compounds. There are three types of fluorescence peaks in the DOM samples,that is,aromatic protein peaks,dissolved microbial metabolite peaks and marine humic acid peaks. And 93. 3% of the samples show the fluorescence peaks of aromatic protein. The increasing fluorescence index ( FI) from 1. 85 to 2. 77, the fluctuating biogenic index ( BIX) between 0. 78 - 1. 23, and the values of SUVA254≤0. 7 L / (m·mg) for the samples confirm that the DOM of the gangue is mainly derived from microbial source (endogenous) organic matter,which is closely correlated with biological or bacterial activity.