川西平原还田秸秆腐解释放DOM的光谱特征

发布时间：2018-02-24 09:31

  本文关键词： 秸秆 溶解性有机质 腐解 光谱学特征 川西平原　出处：《光谱学与光谱分析》2017年09期 　论文类型：期刊论文

【摘要】：为掌握川西平原保护性耕作模式下还田秸秆腐解过程的光谱学特性,追溯还田秸秆对川西地区生态系统结构的影响过程,采集了该地区主要种植作物油菜、水稻的秸秆样本,利用紫外-可见吸收光谱(UVVis)、三维荧光光谱(3D-EEM)和傅里叶变换红外光谱(FTIR)三种光谱学表征手段,阐明秸秆各腐解阶段溶解性有机质(DOM)的光谱学特征,对比不同农作物秸秆快速淋溶阶段DOM(0~0.5d)与腐解过程(0.5~90d)的光谱学特征差异性,解析其变化机理。结果表明:还田秸秆腐解过程中DOM的光谱学特性差异明显,伴随着芳香性物质的溶出、降解以及新生腐殖类物质的形成;由秸秆快速淋溶阶段释放DOM的E_2/E_3值最大而SUVA_(254)值最小可知该阶段溶出的物质芳香性和分子量相对较小;其芳香性组分的溶出主要集中在腐解前期(≤10d),表现于该阶段E_2/E_3值逐渐减小且SUVA_(254)值逐渐增大,DOM中多糖峰、芳香C和酰胺峰变弱;难分解的纤维素、半纤维素和大分子蛋白质主要在腐解后期被降解;DOM中酚类、羰基类和羧酸类物质数量增加,使得DOM与有机污染物、金属离子的相互作用增强,进而调节农田土壤中污染物的迁移转化过程。本研究为川西平原秸秆还田的环境意义提供了基础数据和新证据,为该地区农业废弃物处理与资源化提供了依据。
[Abstract]:In order to understand the spectral characteristics of straw decomposition under conservation tillage in West Sichuan Plain, the effects of returning straw on ecosystem structure of western Sichuan were traced, and the straw samples of rape and rice were collected. The spectroscopic characteristics of dissolved organic matter (DOM) in various stages of decomposition of straw were elucidated by means of UV-Vis absorption spectrum, 3D-EEM and FTIR. The spectral characteristics of DOM in the rapid leaching stage of different crop straw were compared with that in the decomposing process (0.5 ~ 90 d), and the mechanism of the change was analyzed. The results showed that the spectral characteristics of DOM were obviously different during the decomposing process of straw in the field. With the dissolution and degradation of aromatic substances and the formation of new humic substances, the E _ 2 / E _ (3) of DOM released from the rapid leaching stage of straw was the largest and the value of SUVA _ (254) was the lowest. The aromaticity and molecular weight of the substances dissolved at this stage were relatively small. The dissolution of aromatic components was mainly concentrated in the early stage of decomposition (鈮，

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