Characterization of binding site heterogeneity for copper within dissolved organic matter fractions using two-dimensional correlation fluorescence spectroscopy

The heterogeneity of copper binding characteristics for dissolved organic matter (DOM) fractions was investigated based on the fluorescence quenching of the synchronous fluorescence spectra upon the addition of copper and two-dimensional correlation spectroscopy (2D-COS). Hydrophobic acid (HoA) and hydrophilic (Hi) fractions of two different DOM (algal and leaf litter DOM) were used for this study. For both DOM, fluorescence quenching occurred at a wider range of wavelengths for the HoA fractions compared to the Hi fractions. The combined information of the synchronous and asynchronous maps derived from 2D-COS provided a clear picture of the heterogeneous distribution of the copper binding sites within each DOM fraction, which was not readily recognized by a simple comparison of the changes in the synchronous fluorescence spectra upon the addition of copper. For the algal DOM, higher stability constants were exhibited for the HoA versus the Hi fractions. The logarithms of the stability constants ranged from 4.8 to 6.1 and from 4.5 to 5.0 for the HoA and the Hi fractions of the algal DOM, respectively, depending on the associated wavelength and the fitted models. In contrast, no distinctive difference in the binding characteristics was found between the two fractions of the leaf litter DOM. This suggests that influences of the structural and chemical properties of DOM on copper binding may differ for DOM from different sources. The relative difference of the calculated stability constants within the DOM fractions were consistent with the sequential orders interpreted from the asynchronous 2D-COS. It is expected that 2D-COS will be widely applied to other DOM studies requiring detailed information on the heterogeneous nature and subsequent effects under a range of environmental conditions.     

Fenton法降解垃圾渗滤液中的溶解性有机质

垃圾渗滤液是一种高浓度难降解废水,含有大量有毒物质和溶解性有机质（dissolved organic matter, DOM）,可生化性差。Fenton试剂（Fe2++H2O2）能产生活性极强的羟基自由基（·OH）,能快速氧化渗滤液中DOM和微量有机物质。本研究采用Fenton法处理垃圾渗滤液,结果表明,在优化的处理条件下,渗滤液COD和TOC去除率分别为65%和42%,其中混凝作用去除的COD和TOC分别为20%和21%。进一步通过紫外可见光谱扫描、SUVA254、E3/E4等指标评价,发现Fenton法可以有效降低渗滤液中的DOM含量,大分子有机物的含量明显减少,而分子量小的有机物含量相对增加,反应体系中溶解性有机物分子量随着反应的进行而降低,腐殖化程度降低。利用GC-MS定性出渗滤液原液中47种有机物,该类有机物在Fenton反应后上清液中未再检出,但5种物质（邻苯二甲酸二（2-乙基己）酯、植酮、角鲨烯、麥角甾烷醇和二氢胆固醇）在沉淀的铁泥中检出。研究发现不同pH值、H2O2和Fe2+浓度条件下,残留的COD与DOM、TOC和UV254存在显著的相关关系（R2> 0.9）。本研究结果为改进垃圾渗滤液处理工艺和探索DOM在Fenton过程中的降解行为提供科学依据。     

活性炭-超滤深度处理工艺对三氯乙醛生成潜能的影响及其对饮用水中有机物的去除

以我国南方某活性炭-超滤深度处理工艺水厂为研究对象,对工艺过程中三氯乙醛生成潜能(CHFP)及相关有机物指标进行为期1年每月1次的监测,以明晰活性炭-超滤深度处理工艺对CHFP及有机物的去除能力。结果表明:原水CHFP均呈现一定的季节性变化趋势,高温季节(5—9月)相对较高,范围为15.50～64.00 μg·L-1,活性炭-超滤深度处理工艺对CHFP 、TOC、CODMn和UV254去除率范围分别为37.42%～69.12%、25.25%～66.71%、27.33%～61.25%和21.80%～72.46%,平均去除率分别为54.51%、39.21%、45.04%和42.91%;混凝沉淀单元在CHFP和有机物指标去除中均起主要作用,炭滤单元对TOC有较好的去除作用,超滤单元对CHFP和CODMn有较好的去除作用。建议水厂设计与运行中将臭氧与活性炭滤池联合使用,以协同去除CHFP和有机物,进一步提高供水水质。     

基于三维荧光及平行因子分析的南昌市某河可溶性有机物溯源及治理策略

地表河流污染物溯源对污染物防治及河流生态环境改善具有重要意义。三维荧光光谱(3D-EEM)的图谱形状、荧光峰位置、荧光峰强度、荧光峰个数信息和荧光参数可作为水体中可溶性有机物(DOM)的荧光特征。结合平行因子分析(PARAFAC)对南昌市某河的3D-EEMs进行分析并进行DOM溯源研究,结果表明,该河DOM主要包含3个荧光组分,分别为类腐殖质荧光组分C1(λ_Ex/λ_Em=245 nm/430 nm)、类氨基酸和类腐殖质组分的混合物C2(λ_Ex/λ_Em=240,300 nm/365 nm)和类色氨酸荧光组分C3(λ_Ex/λ_Em=225,275 nm/335 nm),分别占总荧光组分的35.93%,26.62%和37.45%。该河基本满足地表水环境质量标准(GB 3838-2002)III类水标准,浮游植物主要为蓝绿藻,河流中磷的来源复杂。污染物溯源结果表明,该河DOM腐殖化程度较低,生物活性较强,主要来源于浮游植物和微生物代谢降解和沉积物在冲击和水力作用下产生的内源污染。建议该河采用生态修复技术并辅助水体曝气系统治理DOM污染,并持续防止河流引入外源污染。