Effect of pH on the Ultraviolet Spectra and Fluorescence Characteristics of Dissolved Organic Matter in the Process of Straw Humification
FAN Chun-hui1, ZHANG Ying-chao2, WANG Jia-hong1
1. College of Resource & Environment, Shaanxi University of Science & Technology, Xi’an 710021, China 2. College of Environment, Tsinghua University, Beijing 100084, China
Abstract：Crop straw is the dominant by-product from agriculture and is regarded as the new source of non-point contamination. Straw incorporation is possible to solve the issues of straw reduction and reutilization, which is clearly required in the twelfth five-year-plan for national economic and social development of the People’s Republic of China. At present, it is of noticeable lack of the investigation on straw incorporation behavior and detail humification product analysis in the representative regions under different environmental conditions. The ultraviolet and fluorescence spectrometry were used to reveal the characteristics of dissolved organic matter (DOM), affected by pH values, in the straw humification process in loess region. The results showed: the ultraviolet absorbance of DOM samples increased firstly and then decreased with the increasing wavelength from 200 to 700 nm, and the maximum absorbance peaks appeared around the wavelength of 240 nm. The maximum absorbance peaks (λmax) were greater at pH values of 6, 8 and 9 than that of 7, and the low degree of humification was indicated from the values of SUVA254, E3/E4 and A253/A203, caused by the short period of humification. The fluorescence peaks of extracted DOM from loess appeared around the regions of λex/em=250/330 and λex/em=325/450, referred as UV fulvic-like fluorescence, and visible fulvic-like and humic-like fluorescence, respectively. The increasing pH values resulted in the greater wavelength of absorbance peak, suggesting the increased aromaticity and conjugated degree, and the novel fluorescence peak was found in λex/em=250/450. The pH values were more effective to change the UV fulvic-like fluorescence peaks intensity (increased firstly and then decreased) than that of visible fulvic-like and humic-like fluorescence, which might be related to buffer effect, fluorescence quenching (side effects) and component structure. The ultraviolet and fluorescence spectrometry were acceptable to illustrate the characteristics variation of DOM affected by pH values in the straw humification process.
范春辉1，张颖超2，王家宏1 . pH值对秸秆腐殖化溶解性有机质紫外光谱和荧光光谱的影响 [J]. 光谱学与光谱分析, 2015, 35(07): 1933-1937.
FAN Chun-hui1, ZHANG Ying-chao2, WANG Jia-hong1 . Effect of pH on the Ultraviolet Spectra and Fluorescence Characteristics of Dissolved Organic Matter in the Process of Straw Humification . SPECTROSCOPY AND SPECTRAL ANALYSIS, 2015, 35(07): 1933-1937.
[1] Zech W, Senesi N, Guggenberger G, et al. Geoderma, 1997, 79(1/2/3/4): 117. [2] Hassan A A R, Usman Y, Smith D S, et al. Comparative Biochemistry & Physiology Part C: Toxicology & Pharmacology, 2013, 158(4): 207. [3] Kalbitz K, Solinger S, Park J H, et al. Soil Science, 2000, 165(4): 277. [4] Cornu J Y, Schneider A, Jezequel K, et al. Geoderma, 2011, 162(1/2): 65. [5] Kaiser K, Kaupenjohann M, Zech W. Geoderma, 2001, 99(3/4): 317. [6] Domeizel M, Khalil A, Prudent P. Bioresource Technology, 2004, 94(2): 177. [7] Weishaar J L, Aiken G R, Bergamaschi B A, et al. Environmental Science & Technology, 2003, 37(20): 4702. [8] Yamashita Y, Tanoue E. Marine Chemistry, 2003, 82(3/4): 255. [9] Korshin G V, Benjamin M M, Sletten R S. Water Research, 1997, 31(7): 1643. [10] CHEN Guo-zhen, HUANG Xian-zhi, ZHENG Zhu-zi, et al(陈国珍, 黄贤智, 郑朱梓, 等). Fluorescence Spectroscopy(荧光分析法). Beijing: Science Press(北京: 科学出版社), 1990. 83. [11] Kalbitz K, Geyer W, Geyer S. Biogeochemistry，1999, 47(2): 219. [12] Ryan D K, Weber J H. Analytical Chemistry，1982, 54(6): 986. [13] Spencer R G M, Bolton L, Baker A. Water Research，2007, 41(13): 2941. [14] Au K K, Penisson A C, Yang S L, et al. Geochimica et Cosmochimica Acta，1999, 63(19/20): 2903. [15] Reynolds D M. Water Research，2003, 37(13): 3055. [16] Stedmon C A, Markager S, Bro R. Marine Chemistry，2003, 82(3/4): 239.
