摘要
土壤溶解性有机质(DOM)由胡敏酸、富里酸等组成。为了解热处理对土壤DOM的结构和组分的影响,将水稻土样品在温度200℃、250℃、300℃和时间2、4、6 h下进行加热,对热处理前后的水稻土DOM进行了紫外光谱、三维荧光和红外光谱分析。结果表明,对于紫外-可见光光谱的特征指标250 nm和365 nm紫外吸光度比值E_2/E_3,随着加热温度增加而逐渐增加,而单位溶解性有机碳浓度下254、260、280 nm处波长SUVA_(254)、SUVA_(260)和SUVA_(280)则逐渐减少,表明随着加热温度增加,DOM的芳香性和疏水性降低;加热后DOM在253 nm与203 nm吸光度的比值A_(253)/A_(203)由低到高,表明未加热时DOM组分芳香环取代基以脂肪链为主,加热后脂肪类物质大量分解。样品加热后的三维荧光光谱发生蓝移现象,荧光强度增加,同时紫外区类富里酸荧光峰值与可见区类富里酸荧光峰值的比值r(A/C)降低,表明加热后土壤DOM芳香性降低,分子量降低。红外光谱特征表明,加热后DOM中羧酸类物质增多;200℃和250℃加热时,DOM中脂肪族类物质增加,300℃加热时脂肪族类物质减少。
Dissolved organic matter（DOM）is an important soil component. It consists of low-molecular-weight free amino acids, carbohydrates, organic acids, and high-molecular-weight enzymes, amino sugars, humus, and so on. It plays an important role in many chemical and biological processes in the soil. In this study, UV-VIS spectra, three-dimensional fluorescence, and infrared spectroscopy were used to analyze the effect of heat treatment on the structure and composition of DOM in different soils. The paddy soil samples were heated at 200 ℃,250 ℃, and 300 ℃ for 2 h, 4 h, and 6 h, respectively. SUVA254, SUVA260, and SUVA280 were the absorption coefficients for unit dissolved organic carbon concentrations at 254, 260, and 280 nm, respectively. The results showed that the ultraviolet absorbance ratio（E2/E3）increased and the SUVA254, SUVA260, and SUVA280 values decreased when the temperature rose. They also indicated that the DOM aromaticity and hydrophobicity decreased when the temperature increased. Furthermore, the A253/A203 absorbance ratio increased when the temperature rose.This indicated that the aromatic ring substituents of the DOM component were mainly aliphatic chains when unheated and that the fatty substances were decomposed in large quantities when heated. The three-dimensional fluorescence spectra showed that a blue-shift in the main fluorescence peak appeared and fluorescence intensity increased. The ratio of the fluorescence peak value of fulvic acid in the ultraviolet re-gion and the fluorescence peak in the visible region decreased. This result showed that the soil aromaticity and the molecular weight decreased after heating. The infrared spectra results showed that the amounts of carboxylic acid substances increased after heating. The aliphatic substances content increased at 200 ℃ and 250 ℃, but decreased at 300 ℃. These results will provide a basis for assessing the environmental risk of contaminants in soils under the influence of heat treatment.
出处
《农业环境科学学报》
CAS
CSCD
北大核心
2018年第3期505-514,共10页
Journal of Agro-Environment Science
基金
国家自然科学基金项目(41403095)
江苏省自然科学基金项目(BK20150265)
江苏省教育厅基金项目(15KJB610002)~~
关键词
溶解性有机物
热处理
腐殖程度
水稻土
光谱特征
dissolved organic matter
heating
humification degree
paddy soil
spectral characteristics
