Sun Li-Ying, Ni Jin-Ren, Sun Wei-Ling
The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Department of Environmental Engineering, Peking University, Beijing 100871, China.
Huan Jing Ke Xue. 2007 Jun;28(6):1324-31.
The concentrations of total organic carbon (TOC) and the NaOH extracted humic substances were analyzed in three size fractions (I : 100 - 300 microm, II : 63 - 100 microm and III : < 63 microm) of sediments sampled in the middle Yellow River. Moreover, UV-visible absorption spectra, fourier transform infrared spectra (FTIR) and three-dimensional excitation emission matrix fluorescence spectra (3DEEM) were used to characterize the chemical structures of the NaOH extracted humic substances in three sediment size fractions. The results show that sediment organic matter in all the size fractions of the collected sediments is dominated by humic substances absorbed on the clay minerals. The proportions of the NaOH extracted humic substances to TOC decrease with decreasing sediment grain size ( I > II > III). This may result from the stronger interaction of the humic substances with clay minerals in finer size fractions of the colleted sediments. Similar UV-visible spectra with different absorbance intensity are observed for the NaOH extracted humic substances in three sediment size fractions. The infrared spectra of the NaOH extracted humic substances show five strong peaks in all fractions of the samples. The area ratios of FTIR peaks suggest that the contents of the phenolic, alcoholic and carboxylic groups account for more than 75% in the NaOH extracted humic substances. Three characteristic excitation-emission peaks present in the 3DEEM of the NaOH extracted humic substances: peak A (UV humic-like compounds), peak C (visible humic-like compounds) and peak T'(phenolic compounds or protein like compounds). UV-visible, FTIR and 3DEEM results imply that the aromatic degree of the NaOH extracted humic substances is higher in fractions I and II than in fraction III. The results also indicate that the aliphatic and aromatic contents are higher in fractions I and II, whilst the phenolic, alcoholic and carboxylic contents are higher in fraction III.
对黄河中游采集的沉积物的三个粒径级分（I：100 - 300微米，II：63 - 100微米，III：< 63微米）中的总有机碳（TOC）浓度和氢氧化钠提取的腐殖质进行了分析。此外，利用紫外可见吸收光谱、傅里叶变换红外光谱（FTIR）和三维激发发射矩阵荧光光谱（3DEEM）对三个沉积物粒径级分中氢氧化钠提取的腐殖质的化学结构进行了表征。结果表明，所采集沉积物的所有粒径级分中的沉积物有机质均以吸附在粘土矿物上的腐殖质为主。氢氧化钠提取的腐殖质占TOC的比例随沉积物粒径减小而降低（I>II>III）。这可能是由于在采集的沉积物较细粒径级分中腐殖质与粘土矿物的相互作用更强。三个沉积物粒径级分中氢氧化钠提取的腐殖质具有相似的紫外可见光谱，但吸光度强度不同。氢氧化钠提取的腐殖质的红外光谱在样品的所有级分中均显示出五个强峰。FTIR峰的面积比表明，氢氧化钠提取的腐殖质中酚羟基、醇羟基和羧基的含量占比超过75%。氢氧化钠提取的腐殖质的3DEEM中出现三个特征激发 - 发射峰：峰A（紫外类腐殖质化合物）、峰C（可见类腐殖质化合物）和峰T'（酚类化合物或类蛋白质化合物）。紫外可见、FTIR和3DEEM结果表明，氢氧化钠提取的腐殖质的芳香度在I级分和II级分中高于III级分。结果还表明，I级分和II级分中的脂肪族和芳香族含量较高，而III级分中的酚羟基、醇羟基和羧基含量较高。
