Departamento de Química e Ciências Ambientais, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista "Júlio de Mesquita Filho", R. Cristóvão Colombo 2265, 15054-000 São José do Rio Preto, SP, Brazil.
Dipartimento Scienze del Suolo, della Pianta, e dell'Ambiente, Università di Napoli Federico II, Via Università 100, 80055 Portici, Italy.
Sci Total Environ. 2015 Jun 15;518-519:201-8. doi: 10.1016/j.scitotenv.2015.02.103. Epub 2015 Mar 7.
Aquatic humic substances (AHSs) differ from one environment to another depending on land use and occupation. In addition, the effects of planting sugarcane on AHSs are not well known. Thus, the aim of this study was to characterize AHSs extracted from a river in a typical region of sugarcane cultivation during dry and rainy seasons. The main characteristics of the AHSs were obtained using Fourier transformation infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and off-line pyrolysis coupled with gas chromatography and mass spectrometry (off-line tetramethylammonium hydroxide (TMAH)-GC-MS-thermochemolysis). The FTIR and NMR results were used to infer that no distinctions occurred between the sampling periods. The samples were composed of aromatic groups that were potentially associated with the presence of residual vegetable materials (lignin). The results of the off-line TMAH-GC-MS-thermochemolysis indicated that the structures of the AHSs had uniform compositions that were rich in fatty acid methyl esters (FAMEs), polysaccharide derivatives, aliphatic biopolymers derived from plants, long hydrocarbon chains, branched alkyl groups and methylene carbons. Thus, the results showed that the AHSs obtained from the sugarcane cultivation area during the crop period mainly consisted of resistant aliphatic hydrocarbons, which are derivatives of lignin and FAMEs in compounds rich in humic acid. Therefore, we concluded that sugarcane cultivation produces changes in AHSs because greater amounts of lignin derivatives were observed during the dry season, corresponding to sugarcane cultivation.
水生腐殖物质（AHSs）因土地利用和占用的不同而在不同环境中存在差异。此外，种植甘蔗对 AHSs 的影响尚不清楚。因此，本研究旨在表征甘蔗种植典型地区河流中 AHSs 在旱季和雨季的特征。使用傅里叶变换红外（FTIR）光谱、核磁共振（NMR）光谱和离线四甲基氢氧化铵（TMAH）-GC-MS-热解联用技术（off-line tetramethylammonium hydroxide (TMAH)-GC-MS-thermochemolysis）获得 AHSs 的主要特性。FTIR 和 NMR 结果表明，采样期之间没有区别。这些样品由可能与残留植物材料（木质素）有关的芳族基团组成。离线 TMAH-GC-MS-热解的结果表明，AHSs 的结构具有均匀的组成，富含脂肪酸甲酯（FAMEs）、多糖衍生物、植物来源的脂肪族生物聚合物、长烃链、支化烷基和亚甲基碳。因此，结果表明，在作物期从甘蔗种植区获得的 AHSs 主要由抗脂肪族烃组成，这些烃是木质素和 FAMEs 化合物中富含有机酸的衍生物。因此，我们得出结论，甘蔗种植会导致 AHSs 的变化，因为在旱季观察到更多的木质素衍生物，这与甘蔗种植有关。
