臭氧氧化对天然有机物在氧化铝表面吸附行为的影响

为进一步明确臭氧预氧化对颗粒的脱稳作用,选用氧化铝（α-Al₂O₃）作为悬浮颗粒,考察了臭氧氧化后天然有机物（natural organic matters,NOM）特性及吸附行为的变化.结果表明,臭氧氧化能够破坏NOM的芳香结构,SUVA值降低25%～35%,氧化后酸性官能团含量增多,总酸度增加0.3～1.4 mmol·g^-1,分子量和极性的变化与NOM的性质有关;有机物初始浓度相对于臭氧投量较低时,NOM的溶解性增强,与其酸性官能团增加产生的吸附促进作用相抵消,因而吸附性能出现不变甚至降低的现象;有机物初始浓度较高时,臭氧能够起到强化NOM吸附的作用.采用2.5　mg·L^-1臭氧进行氧化后,以商用腐殖酸为代表的NOM的吸附形貌,由密集分布的球形对称聚集结构向网状结构过渡,分子之间的交联作用十分明显,吸附高度低于其氧化处理前,云母的表面覆盖率较氧化前略有提高.     

原子力显微观测新生态水合二氧化锰与天然有机物的微观吸附形貌

采用云母片吸附的方式,较好地捕捉到了新生态水合二氧化锰的微观结构,并采用轻敲模式下的原子力显微成像技术,对其吸附天然有机物(NOM)前后的微观形貌进行了观测.与陈化2 h后的水合二氧化锰相比,新生态水合二氧化锰呈现出不定形的穿孔层状结构(厚度仅为0～1.75 nm)和球形颗粒结构,具有大的比表面积和附着能力.当向NOM中加入1 mmol/L新生态水合二氧化锰后,NOM分子的吸附形貌由松散分布的扁平粒状结构(吸附高度为5～8.5 nm)转变为密集分布、水平尺寸均匀的球形结构,表明了NOM分子容易以水合二氧化锰为吸附中心包裹在其表面.从直观上进一步证实了新生态水合二氧化锰的除污染效能,为高锰酸盐的预氧化助凝机理提供了有力的依据.     

水中天然有机物的臭氧强化光催化降解研究

研究了饮用水源中大分子天然有机物（NOM）的臭氧强化光催化降解,考察了臭氧投加量、反应时间和HCO3^-浓度对NOM降解速率的影响;分析了臭氧强化光催化过程中NOM相对分子质量的变化,并比较不同相对分子质量大小NOM的降解速率.研究结果表明,臭氧强化光催化比单独臭氧氧化、光催化能更有效地降解NOM,同时增加臭氧投加量和反应时间才能有效提高臭氧强化光催化对TOC的去除率,而单独增加臭氧投加量可显著提高生物可降解性;HCO3^-显著降低光催化的降解效果,臭氧强化光催化能有效地减弱HCO3^-的不利影响;臭氧强化光催化过程中大分子NOM分解为小分子,SUVA值迅速下降,且相对分子质量越大矿化速度越快.     

水中天然有机物的臭氧化处理

综述了臭氧化处理用于去除水中天然有机物（Natural Organic Matter即NOM）、降低三卤甲烷（TriHalideMethane即THM)生成能方面的国内外研究进展和工程实践情况。指出了臭氧化的功效主要在于（1）直接去除总有机碳（Total Organic Carbon即TOC）或降低三卤甲烷生成能（TriHalideMethane Formation Potential即THMFP);(2)改变有机物分子大小或结构；（3）提高有机物的生化降解性能。     

不同氧化剂降低膜污染效果的研究

采用不同的氧化剂预处理黄浦江原水后进行微滤膜(MF)膜过滤试验,考察预氧化对有机物的去除作用,及其对MF膜过滤特性的影响.结果表明,3种不同氧化剂对有机物的去除效果存在较大差别.臭氧投量在0.5~3.0mg/L范围内,臭氧对DOC和UV254的去除率最高分别为10%和71%;而氯和高锰酸钾对有机物的去除效果则较差.臭氧可将大分子有机物转变成小分子有机物,将大部分疏水性有机物氧化成亲水性有机物.这种有机物组成结构的改变对膜过滤特性产生影响,明显降低了膜污染,膜污染下降率最高可达到22.7%.氯和高锰酸钾的氧化性相对较弱,仅能去除少部分疏水性有机物,对膜污染有较小减缓作用,膜污染下降率最高分别为9%和8.5%.     

天然有机物在氧化铝表面的吸附机理研究

考察了天然有机物(NOM)的2种分离组份(憎水部分HyO,亲水部分HyI)和一种商用腐殖酸(CHA)在氧化铝表面的吸附-解吸行为规律,从芳香性、分子量、极性的角度探讨了NOM自身特性对吸附性能的影响,并通过改变溶液性质(pH值、离子强度、二价阳离子Ca2 ),进一步论证了NOM在金属氧化物表面的吸附机理.结果表明,芳香性高、弱极性的有机物吸附性能较强;降低溶液的pH值,有助于增加吸附剂的吸附容量;离子强度和Ca2 对吸附行为的影响,与NOM自身和内部组分的性质有关.NOM吸附于金属氧化物表面的机理,可以归结为配位体交换、静电作用、憎水作用、阳离子架桥等多个因素共同作用的结果.采用原子力显微成像技术,进一步从微观角度证实了憎水作用和阳离子架桥作用的存在.     

共存有机物对毒死蜱在沉积物上吸附的影响

用批量平衡法研究了共存有机物对毒死蜱在沉积物上吸附行为的影响.结果表明,苯酚和芘对毒死蜱在沉积物上的吸附有竞争作用,其中苯酚的竞争能力较大.多种有机污染物共存时,毒死蜱在沉积物上的吸附仍然由分配作用决定.表面活性剂的浓度小于临界胶束浓度(CMC)时,十二烷基硫酸钠(SDS)能明显降低毒死蜱在沉积物上的吸附量,降低程度与SDS浓度呈负相关,而非离子表面活性剂Triton X-100能增加毒死蜱在沉积物上的吸附量,增加程度与Triton X-100浓度呈正相关.     

FeOOH催化臭氧氧化滤后水中NOM的小分子副产物的生成

以滤后水中富集、分离出的6种不同特性的天然有机物(NOM)组分为对象,考察了羟基氧化铁（FeOOH）催化臭氧氧化NOM各组分后小分子醛、酮及酮酸副产物的生成情况.发现FeOOH催化氧化比臭氧氧化提高了对NOM 各组分DOC和SUVA的去除率.FeOOH催化氧化并不能有效地降低NOM各组分小分子副产物的产量.催化氧化和臭氧氧化后,憎水中性物质(HON)的醛、酮、酮酸的总产量都最高,NOM碱性组分的小分子副产物产量都相对最低.NOM各组分催化氧化后甲醛和丙酮酸的产量最大,这和单独臭氧氧化的结论一致.特别是HON的甲醛产率占其醛、酮总产量的71.6%,单位DOC丙酮酸的产量达78.6 μg/mg.用NOM组分的小分子副产物折算DOC占各组分氧化后DOC的质量分数来间接显示氧化后剩余DOC的可生物降解性,发现催化氧化比单独臭氧氧化进一步提高了滤后水中NOM各组分的可生化性.     

预臭氧化对MF膜处理黄浦江水的影响研究

采用预臭氧化处理黄浦江原水后进行微滤（MF）膜过滤试验,考察预臭氧化对有机物的作用,进而考察其对MF膜过滤特性的影响.结果表明,臭氧投量在0.5～3.0 mg/Ｌ范围内时,臭氧对DOC的去除率最高仅为10%,而对UV254的去除率最高可达71%.随着臭氧投量的增加,相对分子质量在2×10³～7×10³的有机物逐渐减少,而相对分子质量＜0.5×10³的有机物则几乎没有改变.臭氧可把部分疏水性有机物氧化成亲水性有机物,只有很少部分转变成无机物,这种有机物组成结构的改变影响了膜过滤阻力,进而改善了膜透水通量的效果.臭氧投量在0.5～3.0 mg/Ｌ范围内,存在一个最佳的臭氧投量1.5 mg/Ｌ,使膜通量达到最大值.这主要是由于在该臭氧投量下,臭氧化对有机物的组成结构的改变使膜过滤阻力达到最小.     

臭氧预氧化对城市污水二级出水可生化性的影响

以臭氧预氧化强化后续曝气生物滤池对城市污水二级出水中难降解有机物净化效率为目的,研究了臭氧预氧化对二级出水可生化性的影响。臭氧投量为10mg/L、接触时间为4min时,臭氧氧化对COD和TOC去除率分别达到25.7%和16.5%;臭氧氧化使二级出水的生物可降解有机碳(BDOC)值提高为原来的2.45倍;臭氧氧化使二级出水中有机物的分子量分布发生了明显的变化:大分子有机物比例减少,小分子有机物比例增加,使分子量小于1kDalton的有机物的比例由原来的52.9%提高到72.6%;通过UV254值变化可知,臭氧氧化能将大多数含有C=C、C=O双键等活性基团破坏;臭氧氧化后,GC/MS检测到的有机物种类和数量明显增多,氧化前后烷烃种类明显增多,而环状结构、羧酸和醇类化合物明显减少。     

饮用水中有机物组成及控制技术

介绍了饮用水中有机物的组成及其去除评价指标,并指出了各类有机污染物对饮用水水质的影响。重点探讨了水中各类有机污染物的去除方法：强化混凝、颗粒活性碳、膜过滤、光催化氧化、臭氧一生物活性炭及生物预处理技术等。最后总结了各种处理方法的优缺点,为选择合适的去除有机污染物工艺提供参考。     

两个水库型湖泊中溶解性有机质三维荧光特征差异

应用三维荧光光谱技术(3D-EEM),研究了两个典型水库型湖泊(长寿湖和大洪海)水体中溶解性有机质(DOM)的荧光光谱特征,结合沿岸生态系统差异,讨论其对两个湖泊中DOM性质及来源的影响.结果表明,沿岸生态系统的差异性(尤其是人为干扰)是导致两个水体DOM地球化学特征存在明显差异的重要原因.两湖水体中DOM均存在4个荧光峰,且长寿湖样本中类蛋白物质含量更高;而大洪海水体中腐殖化程度较高的组分(C峰)含量较高.相关性分析表明,两湖DOM样本中类蛋白和类腐殖组分来源不同,而A、C峰代表的类腐殖组分存在共源性.通过荧光参数分析显示,沿岸以森林系统为主的大洪海水体DOM陆源性更强,腐殖化程度高;而长寿湖受两岸农田、果园的输入以及人为排放影响,其水体DOM具有明显的自生源特征,新生DOM含量较高,其荧光特征也反映了该区域水体受人为干扰较大.与其他不同湖泊对比,进一步表明沿岸生态系统类型及人为土地利用是决定水体DOM来源和特性的关键因素.     

堆肥处理过程中猪粪有机物的动态变化特征

为了解猪粪堆肥过程中各种有机物的变化特征,并为判断猪粪堆肥腐熟度提供参考指标,进行42d的高温好氧堆肥.结果表明,堆体中的有机质含量呈下降趋势;水溶性有机碳(DOC)含量在第10d达到最大值,之后呈下降趋势;易分解有机质含量呈下降趋势,但在高温开始阶段呈上升趋势;腐殖质含量呈上升趋势.说明堆肥过程中有机物不断向腐殖化方向转化.在研究H/F变化时发现,它与判断堆肥腐熟度常用的化学指标(有机质、DOC)呈一定的相关性,而且与易分解有机质和腐殖质也有较好的相关性.     

Development of an on-line measurement system for water-soluble organic matter in PM2.5 and its application in China

Water-soluble organic matter(WSOM) represents a critical fraction of fine particles(PM_(2.5))in the air, but its changing behaviors and formation mechanisms are not well understood yet, partly due to the lack of fast techniques for the ambient measurements. In this study,a novel system for the on-line measurement of water-soluble components in PM_(2.5), the particle-into-liquid sampler(PILS)–Nebulizer–aerosol chemical speciation monitor(ACSM), was developed by combining a PILS, a nebulizer, and an ACSM. High time resolution concentrations of WSOM, sulfate, nitrate, ammonium, and chloride, as well as mass spectra, can be obtained with satisfied quality control results. The system was firstly applied in China for field measurement of WSOM. The mass spectrum of WSOM was found to resemble that of oxygenated organic aerosol, and WSOM agreed well with secondary inorganic ions. All evidence collected in the field campaign demonstrated that WSOM could be a good surrogate of secondary organic aerosol(SOA). The PILS–Nebulizer–ACSM system can thus be a useful tool for intensive study of WSOM and SOA in PM_(2.5).     

Formation of regulated and unregulated disinfection byproducts during chlorination and chloramination: Roles of dissolved organic matter type, bromide, and iodide

Algal blooms and wastewater effluents can introduce algal organic matter (AOM) and effluent organic matter (EfOM) into surface waters, respectively. In this study, the impact of bromide and iodide on the formation of halogenated disinfection byproducts (DBPs) during chlorination and chloramination from various types of dissolved organic matter (DOM, e.g., natural organic matter (NOM), AOM, and EfOM) were investigated based on the data collected from literature. In general, higher formation of trihalomethanes (THMs) and haloacetic acids (HAAs) was observed in NOM than AOM and EfOM, indicating high reactivities of phenolic moieties with both chlorine and monochloramine. The formation of haloacetaldehydes (HALs), haloacetonitriles (HANs) and haloacetamides (HAMs) was much lower than THMs and HAAs. Increasing initial bromide concentrations increased the formation of THMs, HAAs, HANs, and HAMs, but not HALs. Bromine substitution factor (BSF) values of DBPs formed in chlorination decreased as specific ultraviolet absorbance (SUVA) increased. AOM favored the formation of iodinated THMs (I-THMs) during chloramination using preformed chloramines and chlorination-chloramination processes. Increasing prechlorination time can reduce the I-THM concentrations because of the conversion of iodide to iodate, but this increased the formation of chlorinated and brominated DBPs. In an analogous way, iodine substitution factor (ISF) values of I-THMs formed in chloramination decreased as SUVA values of DOM increased. Compared to chlorination, the formation of noniodinated DBPs is low in chloramination.     

太湖北部湖区春、冬季节天然有机质的荧光特征及环境意义

天然有机质(OM)广泛存在于各类水体,含有丰富的碳、氮、磷等生源要素,其形成、转化、归宿及其相伴随的营养盐再生过程是水生态系统营养盐生物地球化学循环的重要环节,在湖泊蓝藻水华暴发过程中势必也扮演着非常重要的营养盐供给者的角色.本研究于2015年2月和5月分别在太湖北部湖区采集了17个样品,利用POM-DOM PARAFAC三维荧光模型解析春、冬季节颗粒态有机质(POM)和溶解态有机质(DOM)的荧光特征及来源,并探讨POM和DOM各荧光组分之间及其与叶绿素a(Chla)的关系.结果表明,春、冬季节太湖北部湖区POM和DOM的荧光峰、荧光中心位置和荧光强度均存在明显的差别;POM有着比DOM更复杂的组分构成.综合POM和DOM的荧光强度和荧光指数可知,春、冬季节太湖北部湖区POM和DOM均以自生源为主,河口区受陆源贡献较大.POM(C1p~C5p)和DOM(C1d~C5d)有5种荧光组分,分别是类色氨酸(C1和C2)、类腐殖质(C3和C4)及类酪氨酸(C5).POM和DOM的荧光组分特征存在明显的差别;春、冬季节POM均以类腐殖质荧光C3为主,荧光组分高值区分别集中在梅梁湾区域和湖心区;而DOM均以类蛋白组分C2、C1和C5为主,荧光组分高值区均分布在竺山湾区域.相关分析结果显示,春季C1d与C2d(P0.01)、C3d与C4d(P0.01)、C1p与C4p(P0.05)、C2p与C5p(P0.01)均具有较强的相关性.值得注意的是,C3d(P0.01)、C4d(P0.05)与C3p均具有较好的相关关系,表明POM与DOM在组分、来源上具有某种联系.与春季类似,冬季荧光组分C1d与C2d、C3d与C4d、C1p与C2p、C1d与C2p亦具有极好的相关性(P0.01).春季C5d与Chla之间存在正相关关系(P0.01),而C2d(P0.05)、C3p(P0.01)与Chla之间具有负相关关系;冬季C4d与Chla之间也存在负相关关系(P0.05).     

Natural organic matter quantification in the waters of a semiarid freshwater wetland (Tablas de Daimiel, Spain)

Dissolved organic matter (DOM) concentrations have been measured in the waters of a semiarid freshwater wetland, the Tablas de Daimiel, Spain, when the system-characterised by variable hydroperiodicity conditions, was completely flooded (February 2011). Fluxes of DOM from the wetland soils to the overlying waters were measured by using a passive diffusion sampler (peeper). Not only dissolved organic carbon (DOC) concentrations were measured but refractory organic matter (ROM, usually known as humic substances) was also quantified using a novel voltammetric method. Fluorescence spectra were recorded to help in selecting the appropriate standard for ROM quantification, test the homogeneity of DOM in the waters and get an indication of their source. The results obtained show a 7-fold increase in measured ROM concentrations from the Gigu¨ela River to the outlet, which points to a net exportation of ROM from the wetland and to the existence of an internal source of ROM in the system, probably diffusion from the wetland soils. This hypothesis is confirmed by the flux of ROM from the soils to the water column measured with the peeper and by the common fluorescence characteristics of column and interstitial waters. The smaller increase in DOC concentrations along the wetland, in spite of the higher DOC fluxes from soils, suggests that there is significant turnover of organic carbon (OC) in the water column. The system acts as a major carbon sink but, when flooded, exports OC as DOM.     

海洋溶解有机物荧光特征研究进展

20世纪90年代以来,三维荧光光谱技术的应用促进了海洋溶解有机物荧光特性研究的飞速发展,本文对海洋溶解有机物荧光的类型、荧光峰的位置、荧光效率、荧光定性定量,以及荧光与浮游植物增殖的关系、荧光在河口和大洋区的分布等进行了综述.     

二级出水水质对中试臭氧-微滤工艺运行的影响

在以膜微滤为主的组合工艺对二级出水的处理过程中,二级出水水质可能对于微滤过程中膜污染的发展有较强影响.为此考察了2座污水处理厂及1个中试处理设施的二级出水水质,包括常规水质指标、水中颗粒物粒径分布及树脂吸附分离后不同有机物部分的荧光光谱所表征的有机物组分等对于死端微滤中TMP发展变化的影响.研究结果表明:①颗粒物浓度和颗粒物粒径分布对于微滤过程中的可逆污染有较大贡献;②二级出水中的有机物,尤其是其中的腐殖质部分,对于微滤过程中的不可逆污染有较大贡献.     

Impact of land clearing methods and cropping systems on labile soil C and N pools in the humid zone Forest of Nigeria

Labile soil C and N play vital roles in soil–plant nutrient dynamics, especially in the low input cropping system and are vulnerable to perturbation. Surface (0–0.15 m) soils from three land clearing methods (slash and burn, bulldozed non-windrowed and bulldozed windrowed) and each with two cropping systems (5-and 4-year cropping/2-year cassava fallow) were collected in the humid forest ecosystem of Nigeria.The soils were analysed for total C and N, microbial biomass C and N (SMB C and N), particulate organic matter C and N (POM C and N), water-soluble C, potentially mineralizable N (PMN) and mineral N. The size of the labile C and N and their relative contributions to the organic C and total N differed significantly among land clearing methods, irrespective of the cropping system. Soils under slash and burn had a significantly (p > 0.05) higher particulate organic matter C, N (10.80 and 0.16 g kg⁻¹, respectively) and microbial biomass C and N (1.07 and 0.12 g kg⁻¹) compared to the bulldozed windrow, regardless of the cropping system. Four years cropping/2-year cassava fallow resulted in a significant higher labile C and N, relative to 5-year cropped plots across the land clearing methods. Effect of the treatments on the concentration of PMN and mineral N mirrored the SMB N and POM N. However, the quantity of most of the labile C and N pool and crop yield obtained from the slash and burn and bulldozed non-windrowed treatment did not differ significantly. Hence, bulldozed non-windrowed clearing could be a viable alternative to slash and burn in the case of large-scale farming in ensuring reduced losses of soil organic matter and nutrient during land clearing in the humid tropics.