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应用紫外-可见光光谱、傅里叶红外光谱、三维荧光光谱技术对热带地区土壤、堆肥、植物残体3类典型来源水溶性有机质(DOM)的组分进行光谱特性研究,探讨其芳香性、官能团种类、腐殖质成分,初步分析了秸秆粉碎还田和堆肥还田DOM对土壤环境的潜在风险。结果表明:对于紫外-可见光光谱的特征指标SUVA254、SUVA280、A260/TOC,堆肥DOM(木薯杆堆肥DOM>甘蔗叶堆肥DOM)>土壤DOM(水稻田土壤DOM>香蕉地土壤DOM)>植物残体DOM(水稻根系DOM>水稻秸秆DOM),说明堆肥DOM的芳香性最高、分子量最大、疏水性最强。红外光谱特征表明,植物残体DOM具有脂肪烷烃物质、蛋白质物质,含较多的-OH、-CH2、-CH、N-H、C-O基团;堆肥DOM富含酚羟类物质,具有较多C=O、C=C、N-O、C-O、-NH2等活性官能团;土壤DOM红外光谱复杂,主要含较多脂肪族腈、NH4+和一定量-OH、-COOH、C-O。三维荧光光谱分析表明,植物残体DOM富含类黄腐酸物质,并含类蛋白物质;土壤DOM、堆肥DOM均含类腐植酸物质,其中木薯杆堆肥DOM的腐植酸芳香性最高。堆肥DOM有利于污染物在土壤中的固定;植物残体DOM可增加污染物的迁移性,对地下水、地表径流具有潜在环境风险。
The spectral characteristics of three typical DOM sources in soils, composts and plant residues in the tropics were studied by UV-Vis, FT-IR and 3D fluorescence spectroscopy. The effects of their aromaticity, Species and humus composition, and analyzed the potential risks of straw crushing and returning DOM to soil environment. The results showed that: for the characteristics of SUVA254, SUVA280, A260 / TOC, composting DOM (sugarcane bar compost DOM> sugarcane leaf compost DOM)> soil DOM (paddy soil DOM> banana soil DOM)> plant residue DOM (rice root DOM> rice straw DOM), indicating that compost DOM has the highest aromaticity, the highest molecular weight and the strongest hydrophobicity. The infrared spectrum showed that the DOM of the plant residues had fatty alkanes and protein substances, which contained more -OH, -CH2, -CH, NH and CO groups. DOM was rich in phenolic and hydroxyl compounds and had more C = O, C = C, NO, CO, -NH2 and other active functional groups. DOM soil infrared spectroscopy complex, mainly containing more aliphatic nitrile, NH4 + and a certain amount of -OH, -COOH, CO. Three-dimensional fluorescence spectroscopy analysis showed that plant DOM was rich in fulvic acid-like substances and contained protein-like substances. Soil DOM and compost DOM all contained humic acid-like substances, of which DOM had the highest humic acid aromaticity. Composting DOM is conducive to the fixation of pollutants in the soil. Plant residues DOM can increase the migration of pollutants and pose potential environmental risks to groundwater and surface runoff.