Aniline and 2,4,6-trinitrotoluene associate preferentially to low molecular weight fractions of dissolved soil organic matter

Aniline and 2,4,6-trinitrotoluene (TNT) were equilibrated with particulate (POM) and dissolved organic matter (DOM) from an organic soil at different compositions of adsorbed major cations (Na, Al) and pH (aniline: 3.7–5.1, TNT: 4.8–5.0). After separation of POM, concentrations of ¹⁴C-labelled aniline and TNT* (including TNT degradation products) were determined in DOM size fractions using size-exclusion chromatography (SEC) and UV-detection. Concentrations in the <3.5 kDa size fraction were 2.8–6.0 and 8.5–9.5 times higher for aniline and TNT*, respectively, as compared to the >40 kDa fraction. Thus, both aniline and TNT* were preferentially associated to the smallest DOM size fraction. The significant binding to DOM (similar extent as to POM) and the fact that the <3.5 kDa DOM fraction was less susceptible to flocculation by major metals suggests that the mobility of aniline and TNT is highly affected by the solubility of soil organic matter.     

Relating dissolved organic matter fluorescence and functional properties

The fluorescence excitation–emission matrix properties of 25 dissolved organic matter samples from three rivers and one lake are analysed. All sites are sampled in duplicate, and the 25 samples include ten taken from the lake site, and nine from one of the rivers, to cover variations in dissolved organic matter composition due to season and river flow. Fluorescence properties are compared to the functional properties of the dissolved organic matter; the functional assays provide quantitative information on photochemical fading, buffering capacity, copper binding, benzo[a]pyrene binding, hydrophilicity and adsorption to alumina. Optical (absorbance and fluorescence) characterization of the dissolved organic matter samples demonstrates that (1) peak C (excitation 300–350 nm; emission 400–460 nm) fluorescence emission wavelength; (2) the ratio of peak T (excitation 220–235 nm; emission 330–370 nm) to peak C fluorescence intensity; and (3) the peak C fluorescence intensity: absorbance at 340 nm ratio have strong correlations with many of the functional assays. Strongest correlations are with benzo[a]pyrene binding, alumina adsorption, hydrophilicity and buffering capacity, and in many cases linear regression equations with a correlation coefficient >0.8 are obtained. These optical properties are independent of freshwater dissolved organic carbon concentration (for concentrations <10 mg L⁻¹) and therefore hold the potential for laboratory, field and on-line monitoring and prediction of organic matter functional properties.     

Evaluating the impacts of some environmentally relevant factors on the availability of bisphenol A with negligible-depletion SPME

The effect of some environmentally relevant factors including salinity, pH, and humic acids on the availability of bisphenol A (BPA) was evaluated by using the negligible-depletion solid-phase microextraction (nd-SPME) biomimetic method. With the variation of salinity (0–500 mM NaCl) and pH (5.0–8.5) of aqueous solutions, the partition coefficients of BPA between the nd-SPME fiber and the aqueous solution varied in the range of log D = 3.55–3.86, which indicates that the salinity and pH can influence the availability of BPA. By using Acros humic acid as model dissolved organic matter (DOM), it was also demonstrated that the environmental factors such as salinity and pH could affect the partitioning of BPA between DOM and aqueous solutions. The determined partition coefficients of BPA between dissolved organic carbon (DOC) and aqueous solutions were in the range of log D_DOC = 4.03–5.60 for Acros humic acid solutions with 1–50 mg l⁻¹ DOC. The influence of salinity and pH on log D_DOC was more significant at low concentration (0–5 mg l⁻¹) of DOC.     

Characterization of dissolved organic matter in the rhizosphere of hyperaccumulator Sedum alfredii and its effect on the mobility of zinc

Pot experiments were performed to investigate the characteristics of dissolved organic matter (DOM) in the rhizosphere soil of hyperaccumulating ecotype (HE) and a non-hyperaccumulating ecotype (NHE) of Sedum alfredii and its effects on the mobility of zinc (Zn). DOM was fractionated using XAD resins into six fractions. The acid fraction was the predominant component of DOM in the rhizosphere of S. alfredii, with hydrophilic acid (HiA), hydrophilic base (HiB), and hydrophilic neutral (HiN) in HE-DOM being 1.6, 1.9, and 1.2 times higher respectively, as compared to NHE-DOM. ATR-FTIR results showed that DOM in the rhizosphere of S. alfredii consisted of a mixture of hydroxylated and carboxylic acids, and HE-DOM exhibited more CO, OH, CC and CO functional groups than NHE-DOM. Resin equilibration experiment results indicated that DOM from the rhizosphere of both ecotypes of S. alfredii had the ability to form complexes with Zn, whereas the degree of complexation was significantly higher for HE-DOM (60%) than NHE-DOM (42%). The addition of HE-DOM significantly (P < 0.05) increased the solubility of four Zn minerals while NHE-DOM was not as effective at the same concentration. It was concluded that DOM derived from the rhizosphere of hyperaccumulating ecotype of S. alfredii could significantly increase Zn mobility through the formation of soluble DOM-metal complexes, this might be one of the important mechanism by which S. alfredii is involved in activating metal in rhizosphere.     

Microbial degradation of dissolved organic matter (DOM) and its influence on phenanthrene-DOM interactions

Microbial degradation-induced changes in the characteristics of dissolved organic matter (DOM), and the subsequent effects on phenanthrene-DOM interactions were investigated based on the microbial incubation of DOM collected from four different sources for 28 d. Partially biodegraded DOM presented higher specific UV absorbance (SUVA), lower protein-like fluorescence, higher humic-like fluorescence, lower aliphatic carbon fraction, and higher hydrophobic neutral fractions compared to the original DOM. Microbial changes in DOM led to an increase in the isotherm nonlinearity as well as the extent of phenanthrene binding. A negative relationship between SUVA and the Freundlich n values was established for the original and the biodegraded DOM, suggesting that aromatic condensed structures may play important roles in providing nonlinear strong binding sites irrespective of microbial degradation. In contrast, there were two separate slopes of the correlations between the percentage of hydrophobic acid (HoA) fraction and the n values for the original and the biodegraded DOM with a higher slope exhibited for the latter, implying that the microbial utilization of oxygen-containing structures in the HoA fractions may contribute to enhancing the associated isotherm nonlinearity.     

三维荧光区域积分评估城市污水中溶解性有机物去除

以三维荧光技术为手段,结合荧光区域积分和聚类分析,考察某城市污水厂污水处理过程中溶解性有机物的去除状况。研究结果表明,采用三维荧光区域积分可以表征城市污水中易降解、可降解和难降解有机物相对含量的变化趋势,能够有效识别污水中溶解性有机物的指纹特征。城市污水中类蛋白等易降解物质含量约占总荧光物质的50%,在污水厂曝气池缺氧段,易降解基质被大量去除。曝气池顺水流方向约225 m处,溶解性有机物的去除已基本完成。三维荧光光谱中区域II和III的积分标准体积与TOC的皮尔森相关指数分别为0.964和0.970。和其他荧光指数相比,这2个区域的积分标准体积与TOC的相关度更高。     

城市污水处理过程中溶解性有机物转化特性

运用反渗透技术对城市处理厂进出水中的溶解性有机物(DOM)进行浓缩富集,利用DAX-8大孔树脂将DOM分为亲水物质(Hy I)、类富里酸(FA)和类腐殖酸(HA)3种组分。研究表明,原污水中有机物各组分经生物处理后的总量去除近90%,各组分所占总TOC的百分含量在生化反应过程中也发生了变化:出水中HA组分有降低的趋势,平均下降9.77%,而FA和Hy I两大组分所占总和呈现上升趋势,其中类FA物质升高7.94%,而Hy I组分百分比略有下降。与进水相比,出水中Hy I、FA和HA组分在Ⅲ(色氨酸)、Ⅳ(酪氨酸)区的荧光峰全部消失,而在Ⅰ(类腐殖酸)、Ⅱ(类富里酸)荧光峰变化不大。SUVA和电位滴定结果表明出水有机物的结构发生变化,各组分的芳香性比进水有机物有所增加。研究结果表明,进水中的有机物在污水处理过程中,小分子物质可以被生物利用并形成新的代谢产物释放到水中,大分子物质却较难被生物利用,但在处理过程中其分子构造在一定程度上被微生物改变,系统的生化驯养可以达到构造改变的效果,从而影响出水各组分分子量变化。     

Reverse quantitative structure-activity relationship for modelling the sorption of esfenvalerate to dissolved organic matter. A multivariate approach

The sorption of the pyrethroid, esfenvalerate, to the dissolved and/or dispersed fraction of eight different natural humic compounds has been investigated. The dissolved organic matters (DOMs) included in this study originate from ground water, soil pore water, and surface waters. Sorption was modelled at DOM concentration levels where equilibrium partitioning of esfenvalerate between DOM and the aqueous bulk phase prevails. The inherent characteristics of the eight different humic materials, quantified in the preceding paper by Thomsen et al. (2002, this issue (PII: S0045-6535(02)00335-1)), have been used as explanatory variables for modelling this equilibrium partitioning. Using a reverse QSAR approach based on by projection-into-latent-structure regression (PLS-R) inherent sorbent properties determining for the sorption affinity of esfenvalerate to DOM were analysed. For all humic substances a decrease in the DOM-normalised equilibrium-partitioning coefficient, K_DOM, with increasing concentration of DOM was observed. Significant variations in K_DOM values, as function of the inherent characteristics of the individual humic substances, were found at DOM concentrations of 75 and 100 ppm, respectively. The latter is a strong indication of variations in sorption mechanisms of esfenvalerate to DOM of varying inherent properties. Groupings in the principal property space quantifying DOMs may indicate that separate models are needed for quantifying the equilibrium partitioning to different classes of DOM.     

Removal of dissolved organic matter in municipal effluent with ozonation, slow sand filtration and nanofiltration as high quality pre-treatment option for artificial groundwater recharge

In the paper the combination process of ozonation, slow sand filtration (SSF) and nanofiltration (NF) was investigated with respect to dissolved organic matter (DOM) removal as high quality pre-treatment option for artificial groundwater recharge. With the help of ozonation leading to breakdown of the large organic molecules, SSF preferentially removes soluble microbial by-product-like substances and DOM with molecular weight (MW) less than 1.0 kDa. NF, however, removes aromatic, humic acid-like and fulvic acid-like substances efficiently and specially removes DOM with MW above 1.0 kDa. The residual DOM of the membrane permeate is dominated by small organics with MW 500 Da, which can be further reduced by the aquifer treatment, despite of the very low concentration. Consequently, the O₃/SSF/NF system offers a complementary process in DOM removal. Dissolved organic carbon (DOC) and trihalomethane formation potential (THMFP) can be reduced from 6.5 ± 1.1 to 0.7 ± 0.3 mg L⁻¹ and from 267 ± 24 to 52 ± 6 μg L⁻¹, respectively. The very low DOC concentration of 0.6 ± 0.2 mg L⁻¹ and THMFP of 44 ± 4 μg L⁻¹ can be reached after the aquifer treatment.     

白洋淀沉水植物腐解溶解性有机物与重金属的相互作用

针对白洋淀秋冬季节水生植物腐解释放大量溶解性有机物(DOM)的问题,利用紫外可见光谱(UV-Vis)和激发发射光谱(EEMs)结合平行因子分析法(PARAFAC)对DOM样品进行表征和分离。实验结果表明,PARAFAC共分离出4种组分(C1、C2、C3和C4),类腐殖酸组分C1和C2、类蛋白组分C3、含有类蛋白组分和类富里酸组分共同组成的C4。此外,对样品进行荧光淬灭滴定实验来研究DOM与重金属(Cu (Ⅱ)和Cd (Ⅱ))的相互作用,发现Cu (Ⅱ)对所有组分都存在明显的淬灭效果,并可以较好地拟合出络合常数(lgK),而Cd (Ⅱ)只与C4有较好的络合效果,这是由于C4中的类富里酸成分所造成的。研究进一步发现,样品U2中类蛋白组分C3和C4对重金属的淬灭效果比样品U0的类蛋白组分明显。这是由于样品U2中所添加的植物量较多,而植物腐解所释放的主要成分为类蛋白物质,有助于增强类蛋白组分的络合能力。研究结果可为科学评价水生植物腐解释放DOM对水体中重金属的迁移转化提供依据。     

Molecular characterisation of the dissolved organic matter of wastewater effluents by MSSV pyrolysis GC-MS and search for source markers

Microscale sealed vessel pyrolysis (MSSVpy) was used to characterise the hydrophobic (HPO) and colloid (COL) fractions of dissolved organic matter (DOM) from the effluents (EFFs) of two waste water treatment plants (WWTPs) and several primary source waters (SWs). The EFFs showed a large range of anthropogenically sourced organics - including the metabolites of industrial chemicals (e.g., dioxanes, n- and sec-alkyl substituted benzenes and long chain alkyl phenols), pharmaceuticals (e.g., N- and S-heterocycles) and human waste (e.g., S- and N-organics, steranes/sterenes) - as well as high concentrations of alkyl aromatic and N-organic products (e.g., alkyl indoles, carbazoles and β-carbolines) attributed to the treatment biota. Some anthropogenic chemicals are potentially toxic at even trace levels, whilst the N-organics may be precursors for toxic N-disinfection by-products. Much lower concentrations of just a few of the anthropogenic and N-organic products were detected by more traditional flash pyrolysis (Flash-py) of the EFF samples, reflecting the higher sensitivity of MSSVpy to many chemical functionalities. Few of these products were detected in the corresponding MSSVpy analysis of the SWs, but these samples did show relatively high abundances of lignin (e.g., alkylphenols) and carbohydrate (e.g., furans) derived products. Their lower EFF abundances are consistent with efficient removal by the water treatment procedures applied. Conversely, the detection of the anthropogenics in the treated EFFs reflects their general resistance to treatment. Their occurrence in the HPO fractions isolated by XAD resin separation suggests a potential relationship with the structurally stable macromolecular fraction of the DOM.     

Diagnosis of dissolved organic matter removal by GAC treatment in biologically treated papermill effluents using advanced organic characterisation techniques

Granular activated carbon (GAC) exhaustion rates on pulp and paper effluent from South East Australia were found to be a factor of three higher (3.62 cf. 1.47 kg m⁻³) on Kraft mills compared to mills using Thermomechanical pulping supplemented by Recycled Fibre (TMP/RCF). Biological waste treatment at both mills resulted in a final effluent COD of 240 mg L⁻¹. The dissolved organic carbon (DOC) was only 1.2 times higher in the Kraft effluent (70 vs. 58 mg L⁻¹), however, GAC treatment of Kraft and TMP/RCF effluent was largely different on the DOC persisted after biological treatment. The molecular mass (636 vs. 534 g mol⁻¹) and aromaticity (5.35 vs. 4.67 L mg⁻¹ m⁻¹) of humic substances (HS) were slightly higher in the Kraft effluent. The HS aromaticity was decreased by a factor of 1.0 L mg⁻¹ m⁻¹ in both Kraft and TMP/RCF effluent. The molecular mass of the Kraft effluent increased by 50 g mol⁻¹ while the molecular mass of the TMP/RCF effluent was essentially unchanged after GAC treatment; the DOC removal efficiency of the GAC on Kraft effluent was biased towards the low molecular weight humic compounds. The rapid adsorption of this fraction, coupled with the slightly higher aromaticity of the humic components resulted in early breakthrough on the Kraft effluent. Fluorescence excitation-emission matrix analysis of the each GAC treated effluent indicated that the refractory components were higher molecular weight humics on the Kraft effluent and protein-like compounds on the TMP/RCF effluent. Although the GAC exhaustion rates are too high for an effective DOC removal option for biologically treated pulp and paper mill effluents, the study indicates that advanced organic characterisation techniques can be used to diagnose GAC performance on complex effluents with comparable bulk DOC and COD loads.     

有机物性质对混凝-微滤-纳滤去除水中重金属的影响

为了探明有机物性质对混凝-微滤-纳滤去除水中重金属的影响,将腐殖酸和乙酸分别作为背景有机物,系统考察了组合工艺对镉(Cd)、铜(Cu)、镍(Ni)和锌(Zn)的去除效能及其膜通量变化过程,并通过物料衡算对4种重金属的去除行为进行了比较分析。结果表明,当原水中不含有机物时,Cu的截留率最高,达到97%以上,纳滤膜是去除其他3种重金属的主要步骤。随着原水中腐殖酸含量的增大,混凝-微滤阶段对重金属的截留能力显著增强,膜通量衰减速度加快。相反地,乙酸的存在对于组合工艺处理效能具有明显的负面效应。此时,重金属既不能被铝盐絮体有效吸附,也不能通过静电作用截留在NF膜表面。4种重金属在滤液和浓水中的回收率Rrec都超过了80%,膜通量的变化与处理无机重金属溶液时相近。     

SBR-混凝处理渗滤液过程中有机物的变化特征

考察了SBR-混凝组合工艺对垃圾渗滤液中溶解性有机物(DOM)不同分子量区间物质及组分腐殖酸(HA)、富里酸(FA)和亲水性有机物(HyI)的去除效果,同时利用傅里叶红外光谱及三维荧光光谱对处理过程中DOM各组分变化特性进行了分析。结果表明,组合工艺对表观分子量为2 000~4 000及<2 000的DOM去除率分别为89.3%和72.1%;对渗滤液DOM组分HA、FA和HyI的去除率分别为-52.0%、73.1%和77.1%。红外光谱显示,DOM各组分都含有醇、羧酸、脂等多种有机物,SBR对糖、醇、羧酸等去除效果较好,而混凝对脂肪族及芳香族化合物去除效果较好;三维荧光光谱分析表明,经组合工艺处理,DOM各组分荧光峰强度及复杂化程度明显降低,且SBR工艺对色氨酸等类蛋白物质去除效果较好,混凝工艺对类腐殖酸、类富里酸等大分子物质的去除效果较好。     

pH和溶解性有机质对磺胺甲恶唑光降解的影响

为了考察pH和溶解性有机质(DOM)对磺胺甲恶唑(SMX)自然光降解的影响,采用光化学反应器对SMX降解过程进行模拟实验,并利用傅里叶变换红外光谱(FT-IR)和三维荧光光谱(3DEEM)对腐殖酸进行表征。结果表明：SMX光解过程符合准一级反应动力学方程,在中等酸性条件下反应速率明显高于中性或碱性条件;添加不同浓度的Pahokee泥炭腐殖酸(PPHA)和Sigma-Aldrich腐殖酸(SigHA)时,均对SMX的光降解产生了不同程度的抑制作用;FT-IR检测发现,PPHA与SigHA均含有含氧官能团,具有一定的还原能力,3DEEM显示PPHA具有荧光特性,可能和SMX结合生成配合物。pH影响SMX的光解与物质本身的酸离解常数有关,对光子的竞争、淬灭作用和掩蔽效应可能是PPHA和SigHA对SMX光降解抑制作用的主要原因。     

水体溶解性有机物的化学分级表征:原理与方法

综述了水体溶解性有机物(DOM)的化学分级表征法即树脂吸附分级法(RA)的研究与进展,同时基于该方法存在的一些问题结合我国典型水质体系,从树脂的选择、净化、分级的定义、水样过柱流速、水样树脂体积比的确定等方面进行了研究探讨,给出了完整的实验参数和操作方法.     

Ubiquity of bisphenol A in the atmosphere

Bisphenol A (BPA) is a suspected endocrine disruptor in the environment. However, little is known about its distribution and transport in the atmosphere. Here, the concentrations of BPA in the atmospheric aerosols from urban, rural, marine, and the polar regions were measured using solvent extraction/derivatization and gas chromatography/mass spectrometry technique. The concentrations of BPA (1-17,400 pg m⁻³) ranged over 4 orders of magnitude in the world with a declining trend from the continent (except for the Antarctica) to remote sites. A positive correlation was found between BPA and 1,3,5-triphenylbenzene, a tracer for plastic burning, in urban regions, indicating that the open burning of plastics in domestic waste should be a significant emission source of atmospheric BPA. Our results suggest that the ubiquity of BPA in the atmosphere may raise a requirement for the evaluation of health effects of BPA in order to control its emission sources, for example, from plastic burning.     

典型南方水源溶解性有机物荧光特性变化与去除

于2014年4-9月,研究我国一典型南方水源溶解性有机物(DOM)的荧光特性变化与去除情况,同时分析了DOM荧光组分与三氯乙醛生成势(CHFP)的相关性。结果表明,该水源DOM主要以芳香性蛋白质类物质组成,溶解性微生物代谢产物类物质、富里酸类物质和腐殖酸类物质含量逐渐增加;5个荧光区域的积分体积(ΦⅠ,n、ΦⅡ,n、ΦⅢ,n、ΦⅣ,n和ΦⅤ,n)所占总体积(ΦT,n)平均比例依次为:13.55%、27.53%、25.00%、16.02%和17.91%;原水DOM的CHFP范围为27.06~81.20μg/L,平均值为46.60μg/L,三氯乙醛(CH)前体物含量与水体中溶解性微生物代谢产物类物质相关性最好;与常规处理工艺相比,O3/BAC深度处理工艺对于溶解性微生物代谢产物类物质的去除率大幅提高,更有利于CH的控制。     

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。     

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.