1. 沈阳师范大学生命科学学院，辽宁 沈阳 110034
2. Department of Soil and Crop Sciences, Colorado State University, Fort Collins, CO, 80523-1170, USA
Spectral Characteristics of Dissolved Organic Matter (DOM) in Leachate Released From Agricultural Soil Irrigated With Reclaimed Water
FAN Chun-hui1, 2, XIN Yi-bei1, YUAN Wen-jing1
1. College of Life Sciences, Shenyang Normal University, Shenyang 110034, China
2. Department of Soil and Crop Sciences, Colorado State University, Fort Collins, CO, 80523-1170, USA
Abstract：Agricultural irrigation is effective for the reutilization of reclaimed water, and the natural advantages and operational feasibility have been generally approved. Agricultural irrigation with reclaimed water can achieve acceptable ecological, social and economic benefits, while organic matters in the soil might lose or change during the irrigation process, and the related issue has received insufficient attention. Dissolved organic matter (DOM) was selected as the analysis target, and the scientific issue was to reveal the variation mechanism of DOM spectral information in leachate released from the irrigated agricultural soil. Samples of reclaimed water (from wastewater treatment plant) and surface water (from the river, for contrast) were used, and a one-dimensional undisturbed soil column was applied to study the irrigation effect on soil and soil leachate. The electronic scanning microscopy (SEM), ultraviolet-visible spectroscopy (UV-Vis) and three-dimensional excitation-emission matrix fluorescence spectroscopy (3D-EEMs) were involved in reveal the fundamental information of DOM released from soil irrigated with water samples. The results show: that soil aggregates appear lose structure and rough surface after irrigation, and small soil particles gather and stick together. The contents of organic matter decrease with the increased soil depth, and DOM content reaches maximal at 10~20 cm of the soil layer. The concentrations of organic matter (0~30 cm of soil layer) and DOM (0~20 cm of soil layer) increase after irrigation, suggesting the interception effect of water organic compounds by soil samples. The UV-Vis spectra of leachate are similar, and the unsaturated double-bond conjugate structures cause the absorption regions at 240~270 nm in DOM. The lower aromatization degree and more straightforward structure of DOM can be detected in soil leachate irrigated with reclaimed water, and the content of fulvic acid is higher than that of humic acid. The only fluorescence peak of DOM appears in theEx/Em=260～270/420～430 nm, regarded as a humus-like component. Compared to the previous results, it is deduced that amino acid-like and protein-like components might be adsorbed and retained in soil. Bio-source (endogenous) DOM plays a more important role than exogenous DOM in soil leachate. The achievements are significant to estimate further the circulation, transportation and ecological effect of DOM or organic matters in the reclaimed water-irrigated agricultural soil systems.
[1] Schmidt M P, Martinez C E. Geoderma, 2019, 344: 63.
[2] Martinez-Perez A M, Catala T S, Nieto-Cid M, et al. Progress in Oceanography, 2019, 170: 93.
[3] Hussain M I, Muscolo A, Farooq M, et al. Agricultural Water Management, 2019, 221: 462.
[4] Gu W L, Huang S B, Lei S, et al. Science of the Total Environment, 2019, 691: 407.
[5] Liu C, Wang H L, Li P H, et al. Science of the Total Environment, 2019, 650: 1988.
[6] Fan C H, Zhang Y C. Environmental Science and Pollution Research, 2018, 25: 25243.
[7] State Environmental Protection Administration of China(国家环境保护总局). Monitoring and Analyzing Methods for the Examination of Water and Wastewater, 4th ed (水和废水监测分析方法, 第4版). Beijing: China Environmental Sciences Press(北京: 中国环境科学出版社), 2002.
[8] LU Ru-kun(鲁如坤). Methods of Soil and Agrochemical Analysis(土壤农业化学分析方法). Beijing: China Agricultural Science and Technology Press(北京: 中国农业科技出版社), 2000.
[9] Bittar T B, Stubbins A, Vieira A A H, et al. Marine Chemistry, 2015, 177: 205.
[10] Ni M F, Li S Y. Journal of Hydrology, 2019, 574: 430.
[11] Wang L J, Wu X Q, Zhao Z Y, et al. Journal of Agricultural and Food Chemistry, 2020, 68: 2329.
[12] Begum M S, Jang I, Lee J M, et al. Science of the Total Environment, 2019, 676: 105.
[13] Lyu S D, Chen W P. Environmental Science and Pollution Research, 2016, 23: 4639.
[14] Wells M J M, Mullins G A, Bell K Y, et al. Environmental Science and Technology, 2017, 51: 13592.
