[Effect of pH on the fluorescence characteristic of dissolved organic matter in landfill leachate].

Due to its high sensitivity, good selectivity and nondestructivity nature, fluorescence technique is suitable to the study of DOM. In the present study, fluorescence characteristics of dissolved organic matter (DOM) from three different ages of landfill leachate (1a, 5a, 10a) under different pH value were investigated. The fluorescence synchronous scan spectroscopy showed that, in addition to the characteristic each age of landfill leachate owned separately, DOM from three ages of landfill leachate shared some common characteristics with the change in pH as follows: the fluorescence peaks of DOM exhibited in synchronous scan spectroscopy from 1 and 5-year-old leachate showed the maximum fluorescence intensity at pH 5, while that of DOM from 10-year-old landfill leachate appeared at pH 12, and the fluorescence intensity of most fluorescence peaks of DOM from 10-year-old landfill leachate exhibited in synchronous scan spectroscopy at pH 4 ranked second. The three-dimensional fluorescence excitation-emission matrix spectroscopy (3DEEM) suggested that the fluorescence intensity of the protein-like peaks of DOM from all three ages of landfill leachate increased with pH value increasing, and the maximum fluorescence occurred at pH 10, while that of DOM from 10-year-old appeared at pH 8; the fluorescence intensity of the visible fulvic-like peaks of DOM from all three ages of landfill leachate was enhanced with pH increasing, and exhibited the maximum fluorescence intensity at pH 10, while the relation curve between the fluorescence intensity of the UV fulvic-like and pH value of DOM from all three year ages of landfill leachate exhibited two peaks, one occurred at pH 4, and the other appeared at pH 10. 3 DEEM also indicated that compared to the fluvic-like matter, the protein-like matter was more easily influenced by pH value. The relation between the r(A,C) value and pH value suggested that the former relied on the latter. If we would compare the r(A,C) values of DOM originating differently, the authors should compare each other under the same pH value.