Gao Jiakai, Liang Chenglong, Shen Guangzhu, Lv Jialong, Wu Haiming
College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China.
College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China; Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, China.
Chemosphere. 2017 Jun;176:108-116. doi: 10.1016/j.chemosphere.2017.02.104. Epub 2017 Mar 2.
Dissolved organic matter (DOM) plays an essential role in many environmental processes, particularly in soil ecosystems. In the present study, ultraviolet-visible (UV-Vis) spectroscopy and parallel factor analysis (PARAFAC) of three-dimensional fluorescence excitation-emission matrices (3D-EEMs) were used to characterize DOM extracted from various agricultural soils across four climate regions of China. The maximum (86.01 mg L) and minimum (17.39 mg L) dissolved organic carbon (DOC) concentrations were found in soils from Jiangsu and Yunnan, respectively. Specific UV-Vis absorption at 254 nm (SUVA) for soil DOM from the temperate continental climate (TCC) region was higher than that of soil DOM in other climate regions. Three fluorescence components including UVC humic-like substances (excitation peak at 400 nm, emission peak at 525 nm), UVA humic-like substances (250(330)/430 nm), and tyrosine-like materials (220(275)/320 nm) were identified in soil DOM using PARAFAC analysis. However, there were no significant differences in the distributions of these three components for soil DOM from different climate regions. Positive correlations were found among the humification index (HIX), fluorescence index (FI), and autochthonous index (BIX). Our results demonstrate that EEMs-PARAFAC could be a feasible approach for characterizing DOM in agricultural soils from different crop systems and can be used to further study complex DOM in agricultural environments.
溶解有机物（DOM）在许多环境过程中起着至关重要的作用，尤其是在土壤生态系统中。在本研究中，利用紫外可见（UV-Vis）光谱和三维荧光激发-发射矩阵（3D-EEMs）的平行因子分析（PARAFAC）对从中国四个气候区的各种农业土壤中提取的DOM进行了表征。发现江苏土壤中的溶解有机碳（DOC）浓度最高（86.01 mg/L），云南土壤中的DOC浓度最低（17.39 mg/L）。温带大陆性气候（TCC）区土壤DOM在254 nm处的比紫外可见吸收（SUVA）高于其他气候区的土壤DOM。利用PARAFAC分析在土壤DOM中鉴定出三种荧光成分，包括UVC类腐殖质物质（激发峰在400 nm，发射峰在525 nm）、UVA类腐殖质物质（250(330)/430 nm）和类酪氨酸物质（220(275)/320 nm）。然而，不同气候区土壤DOM中这三种成分的分布没有显著差异。腐殖化指数（HIX）、荧光指数（FI）和自生源指数（BIX）之间存在正相关关系。我们的结果表明，EEMs-PARAFAC可能是一种表征不同作物系统农业土壤中DOM的可行方法，可用于进一步研究农业环境中的复杂DOM。
