Characterization of natural organic matter in water for optimizing water treatment and minimizing disinfection by-product formation

正Introduction Natural organic matter(NOM)present in source water has significant impact on water treatment processes and on the quality of drinking water.NOM is a complex mixture of diverse groups of organic compounds,humic and fulvic acids,proteins,peptides,carbohydrates,and heterogeneous materials     

Impact of dissolved organic matter on the photolysis of the ionizable antibiotic norfloxacin

Norfloxacin (NOR), an ionizable antibiotic frequently used in the aquaculture industry, has aroused public concern due to its persistence, bacterial resistance, and environmental ubiquity. Therefore, we investigated the photolysis of different species of NOR and the impact of a ubiquitous component of natural water — dissolved organic matter (DOM), which has a special photochemical activity and normally acts as a sensitizer or inhibiter in the photolysis of diverse organics; furthermore, scavenging experiments combined with electron paramagnetic resonance (EPR) were performed to evaluate the transformation of NOR in water. The results demonstated that NOR underwent direct photolysis and self-sensitized photolysis via hydroxyl radical (·OH) and singlet oxygen (¹O₂) based on the scavenging experiments. In addition, DOM was found to influence the photolysis of different NOR species, and its impact was related to the concentration of DOM and type of NOR species. Photolysis of cationic NOR was photosensitized by DOM at low concentration, while zwitterionic and anionic NOR were photoinhibited by DOM, where quenching of UOH predominated according to EPR experiments, accompanied by possible participation of excited triplet-state NOR and ¹O₂. Photo-intermediate identification of different NOR species in solutions with/without DOM indicated that NOR underwent different photodegradation pathways including dechlorination, cleavage of the piperazine side chain and photooxidation, and DOM had little impact on the distribution but influenced the concentration evolution of photolysis intermediates. The results implied that for accurate ecological risk assessment of emerging ionizable pollutants, the impact of DOM on the environmental photochemical behavior of all dissociated species should not be ignored.     

三江平原湿地土壤活性有机碳组分特征及其与土壤酶活性的关系

对三江平原3种主要类型天然湿地(毛苔草湿地、小叶章湿地、岛状林湿地)O-20cm土壤活性有机碳(土壤微生物量碳、土壤可溶性有机碳)特征进行了研究,分析了不同湿地的土壤活性有机碳与土壤总有机碳及酶活性间的关系.结果表明:不同类型湿地的土壤活性有机碳组分含量存在较大的差异,土壤活性有机碳、土壤总有机碳及土壤脲酶、蔗糖酶、淀粉酶、过氧化氢酶的变化趋势具有基本近似的特征.表现为毛苔草湿地>小叶章湿地>岛状林湿地;土壤微生物量碳、可溶性有机碳与土壤总有机碳和酶活性存在显著正相关关系,其中,酶活性与土壤微生物量碳相关性最为显著.另外.毛苔草湿地土壤MBC/SOC、DOC/SOC的比值低于其它2种类型湿地,表明毛苔草湿地生物活性有机碳库的周转速率低.淹水抑制了微生物和酶的分解作用,有利于土壤有机碳的累积.因此,沼泽湿地水文条件的变化将会对土壤碳累积与分解过程产生较大的影响.     

Mercury photoreduction and photooxidation in lakes: Effects of filtration and dissolved organic carbon concentration

Mercury is a globally distributed, environmental contaminant. Quantifying the retention and loss of mercury is integral for predicting mercury-sensitive ecosystems. There is little information on how dissolved organic carbon(DOC) concentrations and particulates affect mercury photoreaction kinetics in freshwater lakes. To address this knowledge gap,samples were collected from ten lakes in Kejimkujik National Park, Nova Scotia(DOC: 2.6–15.4 mg/L). Filtered(0.2 μm) and unfiltered samples were analysed for gross photoreduction, gross photooxidation, and net reduction rates of mercury using pseudo first-order curves. Unfiltered samples had higher concentrations(p = 0.04) of photoreducible divalent mercury(Hg(II)RED)(mean of 754 ± 253 pg/L) than filtered samples(mean of 482 ± 206 pg/L);however, gross photoreduction and photooxidation rate constants were not significantly different in filtered or unfiltered samples in early summer. DOC was not significantly related to gross photoreduction rate constants in filtered(R~2= 0.43; p = 0.08) and unfiltered(R~2= 0.02; p = 0.71) samples; DOC was also not significantly related to gross photooxidation rate constants in filtered or unfiltered samples. However, DOC was significantly negatively related with Hg(Ⅱ)_(RED) in unfiltered(R2= 0.53; p = 0.04), but not in filtered samples(R~2= 0.04;p = 0.60). These trends indicate that DOC is a factor in determining dissolved mercury photoreduction rates and particles partially control available Hg(Ⅱ)_(RED) in lake water. This research also demonstrates that within these lakes gross photoreduction and photooxidation processes are close to being in balance. Changes to catchment inputs of particulate matter and DOC may alter mercury retention in these lakes and could partially explain observed increases of mercury accumulation in biota.     

Microbial bioavailability of dissolved organic nitrogen (DON) in the sediments of Lake Shankou, Northeastern China

Dissolved organic nitrogen(DON)extracted from Lake Shankou sediments using KCl was isolated into hydrophobic and hydrophilic fractions.The bioavailabilities of the hydrophobic and hydrophilic fractions to three types of bacterial communities collected from sediments,activated sludge and compost products were examined.The DON recoveries obtained by DAX-8 and cation exchange resins treatment were 96.17% ± 1.58% and 98.14% ±0% for the samples obtained from N4 and N14 stations,respectively.After 25 days of incubation at 25°C,most DON(59% to 96%)was degraded.Hydrophilic DON exhibited a higher reduction rate than hydrophobic DON during the growth phase.Untreated wastewater from Changshuihe town was the main degradable DON source to station N4,and 93% of hydrophilic DON and 80% of hydrophobic DON were degraded.Station N14 received a large amount of refractory DON from forest soils and exhibited DON degradation rates of 82% and 71% for the hydrophilic and hydrophobic fractions,respectively.Amino acid contents and fluorescence intensities were also analyzed.Approximately 27% to 74% of amino acids were taken up by day 5,and their concentration gradually increased in the following days due to the decomposition of dissolved proteins.Parallel factor analysis resulted in identification of tryptophan-like proteins,tyrosine-like proteins and FA-like substances.During the growth phase,40%–51% of the tryptophan-like proteins were taken up by bacteria,and the accumulation of tyrosine-like proteins was attributed to the release of biotic substances.The concentration of the FA-like substances decreased due to microbial decomposition.     

Revealing the characteristics of dissolved organic matter in urban runoff at three typical regions via optical indices and molecular composition

Dissolved organic matter (DOM) plays a major role in ecological systems and influences the fate and transportation of many pollutants. Despite the significance of DOM, understanding of how environmental and anthropogenic factors influence its composition and characteristics is limited, especially in urban stormwater runoff. In this article, the chemical properties (pollutant loads, molecular weight, aromaticity, sources, and molecular composition) of DOM in stormwater extracted from three typical end-members (traffic, residential, and campus regions) were characterized by UV–visible (UV–vis) spectroscopy, excitation-emission matrix spectroscopy combined with parallel factor analysis (EEM-PARAFAC), and ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). There are three findings: (1) The basic properties of DOM in stormwater runoff varied obviously from three urban fields, and the effect of initial flush was also apparent. (2) The DOM in residential areas mainly came from autochthonous sources, while allochthonous sources primarily contributed to the DOM in traffic and campus areas. However, it was mainly composed of terrestrial humic-like components with CHO and CHON element composition and HULO and aliphatic formulas. (3) The parameters characterizing DOM were primarily related to terrestrial source and aromaticity, but their correlations varied. Through the combination of optical methods and UPLC-Q-TOF spectrometry, the optical and molecular characteristics of rainwater are effectively revealed, which may provide a solid foundation for the classification management of stormwater runoff in different urban regions.     

Growth and alkaline phosphatase activity of Chattonella marina and Heterosigma akashiwo in response to phosphorus limitation

The growth and alkaline phosphatase activity(APA) of two raphidophyceae species Chattonella marina and Heterosigma akashiwo were investigated in response to P-limitation and subsequent addition of dissolved inorganic phosphorus(DIP, Na H2PO4) and two dissolved organic phosphorus(DOP) compounds: guanosine 5-monophosphate(GMP) and triethyl phosphate(TEP). APA levels increased greatly after P-starvation as the decrease of the cellular phosphorus quotes(Qp). C. marina responded to P-limitation quickly and strongly, with 10-fold increase in APA within 24 hr after P-starvation. The larger difference between maximal and minimal QP values in C. marina indicated its high capacity in P storage. APA of H. akashiwo was maximally enlarged about 2.5 times at 48 hr of P-starvation. After the addition of nutrients, cell numbers of C. marina increased in all treatments including the P-free culture, demonstrating the higher endurance of C. marina to P-limitation. However, those of H. akashiwo increased only in DIP and GMP cultures. APA increased only after the addition of the monophosphate ester GMP. The results suggest that quick responses of C. marina to P-limitation, high capacity in P storage as well as endurance for P-depletion provide this species an ecological advantage in phytoplankton community competition under DIP-limited conditions.     

Growth and alkaline phosphatase activity of Chattonella marina and Heterosigma akashiwo in response to phosphorus limitation

The growth and alkaline phosphatase activity (APA) of two raphidophyceae species Chattonella marina and Heterosigma akashiwo were investigated in response to P-limitation and subsequent addition of dissolved inorganic phosphorus (DIP, NaH₂PO₄) and two dissolved organic phosphorus (DOP) compounds: guanosine 5-monophosphate (GMP) and triethyl phosphate (TEP). APAlevels increased greatly after P-starvation as the decrease of the cellular phosphorus quotes (Q_p). C. marina responded to P-limitation quickly and strongly, with 10-fold increase in APA within 24 hr after P-starvation. The larger difference between maximal and minimal Q_p values in C. marina indicated its high capacity in P storage. APA of H. akashiwo wasmaximally enlarged about 2.5 times at 48 hr of P-starvation. After the addition of nutrients, cell numbers of C. marina increased in all treatments including the P-free culture, demonstrating the higher endurance of C. marina to P-limitation. However, those of H. akashiwo increased only in DIP and GMP cultures. APA increased only after the addition of the monophosphate ester GMP. The results suggest that quick responses of C. marina to P-limitation, high capacity in P storage as well as endurance for P-depletion provide this species an ecological advantage in phytoplankton community competition under DIP-limited conditions.     

Growth and alkaline phosphatase activity of Chattonella marina and Heterosigma akashiwo in response to phosphorus limitation

The growth and alkaline phosphatase activity (APA) of two raphidophyceae species Chattonella marina and Heterosigma akashiwo were investigated in response to P-limitation and subsequent addition of dissolved inorganic phosphorus (DIP, NaH₂PO₄) and two dissolved organic phosphorus (DOP) compounds: guanosine 5-monophosphate (GMP) and triethyl phosphate (TEP). APA levels increased greatly after P-starvation as the decrease of the cellular phosphorus quotes (Q_p). C. marina responded to P-limitation quickly and strongly, with 10-fold increase in APA within 24 hr after P-starvation. The larger difference between maximal and minimal Q_P values in C. marina indicated its high capacity in P storage. APA of H. akashiwo was maximally enlarged about 2.5 times at 48 hr of P-starvation. After the addition of nutrients, cell numbers of C. marina increased in all treatments including the P-free culture, demonstrating the higher endurance of C. marina to P-limitation. However, those of H. akashiwo increased only in DIP and GMP cultures. APA increased only after the addition of the monophosphate ester GMP. The results suggest that quick responses of C. marina to P-limitation, high capacity in P storage as well as endurance for P-depletion provide this species an ecological advantage in phytoplankton community competition under DIP-limited conditions.     

上海市秋季大气VOCs对二次有机气溶胶的生成贡献及来源研究

2011年9月1日～11月21日在上海市城区对大气中颗粒物质量浓度和挥发性有机物体积分数进行了在线连续观测.期间共出现4次大气污染过程:PD1(9月20～23日)、PD2(10月5～9日)、PD3(10月13～18日)、PD4(11月10～14日).本测点大气PM2.5的平均浓度分别为(45±16)、(76±46)、(57±36)和(122±92)μg·m-3,VOCs的体积分数分别为(30.87±30.77)×10-9、(32.09±30.69)×10-9、(34.04±28.13)×10-9和(44.27±31.58)×10-9;烷烃、烯烃、芳香烃的体积分数分别占TVOC的53.58%、27.89%、10.96%;用OH消耗速率(LOH)和臭氧生成潜势(OFP)评估了VOCs大气化学反应活性.结果表明,烯烃和芳香烃是本测点秋季大气VOCs中对LOH和OFP贡献最大的关键活性组分.利用气溶胶生成系数FAC和OC/EC比值法估算上海市SOA的生成潜势,两种方法得出的SOA浓度值分别为1.43μg·m-3和4.54μg·m-3,比值法明显较高,这主要是本研究测得的SOA前体物偏少所致.其中芳香烃不仅是OFP的关键活性组分,而且也是SOA的重要前体物.应用PMF模型对VOCs进行源解析,确定了秋季上海市大气中VOCs的6个主要的污染来源,分别为汽车尾气(24.30%)、不完全燃烧(17.39%)、燃料挥发(16.01%)、LPG/NG泄露(15.21%)、石油化工(14.00%)、涂料/溶剂的使用(13.09%).汽车尾气和涂料/溶剂等源排放的VOCs中富含OFP关键活性组分和SOA重要前体物,它们对VOCs浓度的贡献占TVOC的37.39%,这些排放源应列入未来上海市大气复合污染控制的优先范围.     

电渗析预处理测定水中溶解性有机氮浓度的研究

当水样中无机氮(DIN)与总溶解性氮(TDN)质量浓度的比大于0.6时,溶解性有机氮(DON)浓度测定的准确度和标准偏差会受到很大影响。研究了电渗析预处理方式去除水样中部分无机氮离子,对DON浓度测定的影响。结果表明,使用CJM-2型离子交换膜时,并且在对水样适当酸化后溶解性有机碳(DOC)的损失率较小,长江水水样的DOC损失率为5.3%。在最佳工作条下,40 min内对自配水的脱盐率在97%以上。在15 min时,长江水水样中ρ(DIN)/ρ(TDN)0.6,测定出的DON浓度与没有经过电渗析预处理水样相比更加接近真实值,多次测量值(n=4)的标准偏差分别从18.65%下降到3.25%。     

Is there a silver lining? Aggregation and photo-transformation of silver nanoparticles in environmental waters

Is the aggregation of silver nanoparticles in environmental waters a silver lining? The answer is not simple. Clearly, however, the aggregation and photo-transformation of AgNPs are complicated and could be more significant than previously thought. The difference in the water chemistry that controls the aggregation and photo-transformation of AgNPs results in the varying behavior and fate of AgNPs among different water bodies.     

Keep swimming but stop peeing in the pools

正Swimming is excellent exercise and offers many health benefits.However,the"chlorine smell"in swimming pools may be a turn-off for some people.Although this smell is often thought to be of chlorine,it actually comes from volatile compounds that are produced from unintended reactions between disinfectants(e.g.,chlorine)and organic matter in     

Characterisation of dissolved organic matter in stormwater using high-performance size exclusion chromatography

Understanding the complexity of dissolved organic matter(DOM)in stormwater has drawn a lot of interest,since DOM from stormwater causes not only environmental impacts,but also worsens downstream aquatic quality associated with water supply and treatability.This study introduced and employed high-performance size exclusion chromatography(HPSEC)coupled with an ultraviolet–visible(UV–vis)diode array detector to assess changes in stormwater-associated DOM characteristics.Stormwater DOM was also analysed in relation to storm event characteristics,water quality and spectroscopic analysis.Statistical tools were used to determine the correlations within DOM and water quality measurements.Results showed that dissolved organic carbon(DOC)and UV absorbance at 254 nm(UV_(254))as conventional DOM parameters were found to be correlated well to the changes in stormwater quality during each of the three storm events studied.Both detector wavelengths(210and 254 nm)and their ratio(A_(210)/A_(254))were found to provide additional information on the physiochemical properties of stormwater-associated DOM.This study indicated that A_(210)/A_(254) is an important parameter which could be used to estimate the DOM proportions of functional groups and conjugated carbon species.This study provided also an understanding of stormwater quality constituents through assessing variability and sensitivity for various parameters,and the additional information of rainfall characteristics on runoff quality data for a better understanding of parameter correlations and influences.     

施用污泥堆肥及其水溶性有机物对土壤中荧蒽解吸-淋滤的影响

以荧蒽（Fluoranthene）为多环芳烃（PAHs）的代表,通过序批试验及土柱淋洗试验研究了污泥堆肥及污泥堆肥水溶性有机物（DOM）对污染土壤中荧葸解吸和淋滤的影响．施用污泥堆肥实验结果表明,污泥堆肥施入土壤后的短时间内由于带入和产生的DOM而表现出促进土壤中荧蒽的解吸与淋滤,但随着DOM的降解,该作用逐渐消失．污泥堆肥充分腐熟后（腐熟堆肥）因DOM少而稳定的腐殖质等固相有机质含量相对较多,而表现出施用腐熟堆肥后土壤更易对荧葸吸持．单独施用污泥堆肥DOM后的试验,也进一步表明了污泥堆肥DOM的存在确实能促进土壤中荧蒽的迁移,且在相同DOM浓度下,腐熟堆肥DOM对土壤中荧蒽的解吸和淋滤的促进作用明显高于初始堆肥DOM处理,原因在于腐熟堆肥DOM中大分子组分和疏水性组分的含量比初始堆肥的DOM要多．因此,堆肥施用对土壤多环芳烃环境行为或活性的影响是堆肥施人土壤后固相有机质含量及性质和溶解性有机质的含量及性质等综合影响的结果．     

有机气溶胶的来源与形成研究现状

介绍了有机气溶胶来源与形成的研究现状,从有机气溶胶的化学组成特征、一次有机气溶胶的来源和二次有机气溶胶的形成机制论述其研究进展.一次有机气溶胶主要来源于烹调油烟、机动车排放、生物质燃烧、工业或民用燃油锅炉释放出的有机物,还有道路扬尘、沥青、刹车尘、轮胎屑、室外香烟烟雾、以及高等植物蜡、细菌活动和草本植物等.大气中的半挥发性有机物可通过物理和化学吸附形成二次有机气溶胶,一些挥发性有机物可通过气相化学反应转化为低挥发性的物质并形成二次有机气溶胶,其主要前体物是芳香族化合物,如苯、甲苯、二甲苯,以及烯烃、烷烃、环烷烃、萜烯和生物排放的非饱和氧化物.     

水环境中溶解性有机物溯源分析及分子结构表征概述

溶解性有机物(DOM)是地球上最大的碳基化合物反应性储层之一,涉及各种生物地化反应并且在污染物溶解度、毒性、生物利用度、流变性和分布中发挥重要作用。本文介绍了当前用于表征水环境中DOM的策略和工具,探讨了当前研究在技术限制(预处理过程复杂、仪器分辨率低、数据处理困)、结构复杂性、结构多变性等方面存在的诸多局限性。分析认为:已有研究主要侧重于溯源分析和分子结构特征解析,未来研究应该在不同的结构层面和角度开展,加强多学科融合、数据库创建、对照实验和协同工作。     

Total organic halogen (TOX) in human urine: A halogen-specific method for human exposure studies

Disinfection by-products(DBPs) are a complex mixture of compounds unintentionally formed as a result of disinfection processes used to treat drinking water. Effects of long-term exposure to DBPs are mostly unknown and were the subject of recent epidemiological studies. However,most bioanalytical methods focus on a select few DBPs. In this study, a new comprehensive bioanalytical method has been developed that can quantify mixtures of organic halogenated compounds, including DBPs, in human urine as total organic chlorine(TOCl), total organic bromine(TOBr), and total organic iodine(TOI). The optimized method consists of urine dilution, adsorption to activated carbon, pyrolysis of activated carbon, absorption of gases in an aqueous solution, and halide analysis with ion chromatography and inductively coupled plasma-mass spectrometry. Spike recoveries for TOCl, TOBr, and TOI measurements ranged between 78% and 99%. Average TOCl, TOBr, and TOI concentrations in five urine samples from volunteers who consumed tap water were 1850, 82, and 21.0 μg/L as X~-, respectively.Volunteers who consumed spring water(control) had TOCl, TOBr, and TOI average concentrations in urine of 1090, 88, and 10.3 μg/L as X~-, respectively. TOCl and TOI in the urine samples from tap water consumers were higher than the control. However, TOBr was slightly lower in tap water urine samples compared to mineral water urine samples, indicating other sources of environmental exposure other than drinking water. A larger sample population that consumes tap water from different cities and mineral water is needed to determine TOCl, TOBr, and TOI exposure from drinking water.     

2008年奥运期间北京不同粒径大气颗粒物中元素碳和有机碳的变化特征

采用安德森撞击式分级采样器采集2008-06-01～2008-09-30不同粒径的大气颗粒物样品,并用美国沙漠所DRI(desert research institute)的Model 2001A热光碳分析仪对其中的元素碳和有机碳进行了分析.结果表明,平均有56%、55%和73%的PM、OC和EC富集于粒径<2.1 μ...     

Algal uptake of dissolved organic nitrogen in wastewater treatment plants

The algal uptake of dissolved organic nitrogen(DON) in the anaerobic–anoxic–oxic(A_2O)process was investigated in this study. Anaerobic, aerobic and effluent DON samples from two wastewater treatment plants(WWTPs) were separated into hydrophilic and hydrophobic fractions using a DAX-8 resin coupled with an anion exchange resin and a nanofiltration(NF)pretreatment. Hydrophilic DON accounted for 66.66%–88.74% of the entire DON for the two plants evaluated. After a 15-day incubation, 16.95%–91.75% DON was bioavailable for algal growth, and untreated samples exhibited higher DON bioavailability, with 52.83% DON average uptake rates, compared with the hydrophilic and hydrophobic fractions(45.53% and 44.40%, respectively) because the pretreatment caused the inorganic salt to be resistant to algae. Anaerobic untreated samples, hydrophilic fractions and hydrophobic fractions showed higher DON reduction rates and higher biomass accumulation compared with the other DON fractions due to the decomposition of resistant organics by anaerobic and anoxic bacteria.DON in aerobic and effluent samples of plant A was more bioavailable than that of plant B with usages of 27.49%–55.26% DON. DON bioavailability in the anaerobic–anoxic–oxic process decreased in the following order: anaerobic effluent aerobic. The DON contents were reduced after anaerobic treatment in the two plants. The EEM-PARAFAC model identified three DON components, including two humic acid-like substances and one protein-like substance in plant A and two protein-like substances and one humic acid-like substance in plant B.