Environmental chamber study of the photochemical reaction of ethyl methyl sulfide and Nox

A series of experiments were conducted in a self-made smog chamber at 300 ± 1 K and 1.01×105 Pa to simulate the photochemical reaction of ethyl methyl sulfide (EMS) and NOx. The results show that the higher the initial concentration of EMS, the more ozone is generated in the simulative reactions. It is found that the light intensity plays a very important role in the evaluation of ozone formation potential for EMS. The parameters of d(O3-NO) and IR (incremental reactivity) were used to quantify the potential of EMS on ozone formation. The obtained maximum IR values in this paper for the five simulative reactions were 1.55×10-2, 0.99×10-2, 1.36×10-2, 2.47×10-2, and 1.65×10-2, respectively. Comparison between the results we obtained here and the results we obtained before for di-tert-butyl peroxide and acetylene was made and it showed that the potential reactivity of EMS on ozone formation is at a relatively low level.     

三峡支流大宁河库湾水质分布变化原因及其生态效应

为探讨三峡支流大宁河库湾水体水质分布变化的原因及其产生的生态效应,从大宁河库湾污染源、三峡干支流水体交换等视角,建立三峡干流与大宁河库湾交换水量的计算公式,监测大宁河库湾表层水样水质的逐月变化情况,重点分析不同调度期三峡干支流水体交换变化驱动下大宁河库湾水质时空分布的响应变化.结果表明:①三峡干流回水倒灌、大宁河上游来流是大宁河库湾水量、TN、TP等的主要来源,干流表层水体EC（电导率）、ρ（TP）和ρ（TN）均高于大宁河上游来流.②蓄水期至高水位期,在干流回水倒灌作用和库湾水量滞留作用的影响下,库湾表层水体EC、ρ（TP）和ρ（TN）高值分布向上延伸至距离入江口0~20 km及以上的库湾水域.泄水期至低水位期,干支流交换水量为负值,表示库湾流出水量高于干流回水倒灌水量.这两个时期库湾表层水体EC、ρ（TP）和ρ（TN）高值分布首先集中于距离入江口0~5 km的库湾水域,随后向库湾中游方向延伸,可能因泄水后期、低水位期仍有少量干流回水从中表层方向倒灌以及库湾中游藻密度高引起.③5-9月距离入江口0~20 km的库湾中游、下游水域藻密度明显高于其他时期其他水域,与水温适宜、非氮非磷限制的营养结构[TN/TP（摩尔比）为30~40]促进藻类生长繁殖有关.研究显示,不同调度期干支流水体交换是驱动大宁河库湾水质分布变化的重要因素,进而库湾水体氮、磷营养结构的时空变化一定程度上影响着浮游藻类生长分布.      

Photodegradation of new herbicide HW-02 in organic solvents

HW-02 is a new organophosphates herbicide which is discovered and developed in China. The kinetics and mechanism of HW- 02 photodegradation in the organic solvents were studied at 25°C under the irradiation of ultraviolet light. The results showed that photochemical reaction of HW-02 in organic solvents such as n-hexane, methanol, dimethyl benzene and acetone under UV light could be well described by the first kinetic equation, and the photodegradation efficiency decreased with a order of n-hexane methanol xylene acetone. The photodegradation efficiency constant of HW-02 in n-hexane, methanol, xylene and acetone were 4.951 × 10 2 , 3.253 × 10 2 , 2.377 × 10 2 and 1.628 × 10 2 min 1 , and the corresponding half-lives were 13.99, 21.20, 29.15 and 42.56 min, respectively. By separation and identification of photoproducts using GC-MS, it could be concluded that HW-02 was photolyzed through ester cleavage, photo-dechlorination and photoisomerization of the molecule itself.     

应用FCM-qPCR方法定量检测水中常见病原体

以往对水体病原体的研究主要是通过监测粪大肠杆菌作为指示,然而研究表明粪大肠杆菌与水中病毒和细菌病原体呈现出较差的相关性.因此,选取水中典型病原体并对其进行定量检测是当前需要解决的技术问题.为此本研究建立了流式细胞术和定量PCR联合使用方法,用于快速获取水环境中总病毒、细菌以及几种典型病原体(大肠杆菌、军团菌、腺病毒、贾第虫和隐孢子虫等)的浓度水平,并将该方法应用到污水处理厂进出水及受纳河流上下游的病原体检测中.结果表明,该污水处理厂对总细菌和总病毒以及几种典型病原体都具有较高的去除率(93%);污水处理厂排水对受纳水体病原体浓度水平基本没有负面影响.研究为评估污水处理厂处理效果及排水对受纳水体的生态影响提供了技术支持.     

辽河口粪便污染指示菌的时空分布特征

2013年分别于夏季和秋季对辽河口海域的粪便污染指示菌(总大肠菌群、粪大肠菌群和肠球菌)及环境、水化学要素进行分析,研究粪便污染指示菌在海水中的数量、分布特征及其与环境、水化学指标间的相关性,在此基础上,选取河口地区合适的粪便污染指示菌.结果表明:夏季总大肠菌群数量在1.7×105~6.2×106CFU·L-1之间,粪大肠菌群数量在5.0×102~8.7×104CFU·L-1之间,肠球菌数量在1.0×101~2.5×102CFU·L-1之间;秋季总大肠菌群数量在5.0×102~1.1×105CFU·L-1之间,粪大肠菌群数量在4.0×102~1.0×103CFU·L-1之间,肠球菌数量在3~95 CFU·L-1之间.总大肠菌群、粪大肠菌群和肠球菌的数量变化与环境指标之间有着密切联系,特别是与盐度存在显著相关性;粪大肠菌群、肠球菌与水化学指标Si O4-4-Si、NH+4-N、TP和COD之间均存在显著相关性;其中粪大肠菌群与SiO4-4-Si和TP的相关性系数均大于0.742(p0.01),肠球菌与TP和COD的相关性系数均大于0.742.实验结果表明,辽河口粪便污染指示菌的数量在夏季高于秋季,近岸高于远海,其中粪大肠菌群和肠球菌的数量、分布特征与陆源污染物特别是氮磷的输入量密切相关,而且两者之间呈显著正相关关系.粪大肠菌群与肠球菌在一定程度上可以反映河口粪便污染情况,建议采用粪大肠菌群与肠球菌作为河口粪便污染的指示菌.     

Comparison of two methods for detection of fecal indicator bacteria used in water quality monitoring of the Three Gorges Reservoir

Scientifically sound methods to rapidly measure fecal indicator bacteria are important to ensure safe water for drinking and recreational purposes.A total of 200 water samples obtained from the Three Gorges Reservoir during three successive one-year study periods(October 2009 to September 2012) were analyzed using multiple-tube fermentation(MTF)and most probable numbers combined with polymerase chain reaction(MPN–PCR).The MPN–PCR method was found to be significantly more sensitive than the MTF method for detecting Escherichia coli and Enterococcus spp.,and of equal sensitivity for detecting total coliforms when all surface water samples were grouped together.The two analytical methods had a strong,significant relationship,but MPN–PCR took only 12–18 hr,compared with the 3–8 days needed using the MTF method.Bacterial concentrations varied per sampling site but were significantly lower in the mainstream of the Yangtze River than those in the backwater areas of tributaries.The water quality of 85.8% of water samples from the mainstream was suitable for use as a centralized potable water source,while the water quality of 52.5% of water samples from the backwater areas was unsuitable for recreational activities.Relationships between fecal indicator bacteria showed significant correlation(r = 0.636–0.909,p 0.01,n = 200),while a weak but significant correlation was found between fecal indicators and water turbidity,water temperature,daily inflow,and total dissolved solids(r = 0.237–0.532,p 0.05,n = 200).The study indicated that MPN–PCR is a rapid and easily performed deoxyribonucleic acid(DNA)-based method for quantitative detection of viable total coliforms,E.coli,and Enterococcus spp.in surface water.     

北运河粪源微生物分布特征及健康风险评价

河流微生物污染研究对流域水环境保护和公共卫生管理至关重要.本研究以海河流域北运河水系典型河流断面为研究对象,系统评估了北运河水系微生物污染特征及其健康风险.结果表明,北运河水系丰水期的粪源微生物污染严重,大部分断面菌群量超过105MPN·L~(-1),平水期和枯水期粪源微生物菌群量约为103～105MPN·L~(-1),变化不显著;流域内的农业河段粪源微生物最为严重,呈劣五类水体概率超60%,城市河段降雨前后粪源微生物含量变化更明显,部分河流断面的粪源微生物菌群量从103MPN·L~(-1)增长为106MPN·L~(-1); 2017年丰水期,北运河水系粪大肠菌群的单次暴露风险主要在0. 015～0. 035之间,莲花河、马草河、清河下、温榆河下为人体健康风险的关键敏感断面,需重点关注.     

Improvement of detection method of Cryptosporidium and Giardia in reclaimed water

Cryptosporidium and Giardia are two typical species of pathogenic protozoans that seriously endanger water quality. Previous works indicated that detection of Cryptosporidium and Giardia with modified United States Environmental Protection Agency (USEPA) method-1623 using a membrane filtration-elution for sample concentration attained better recovery and lower cost compared to the USEPA method-1623. Several improvements of membrane filtration-elution step as well as immunomagnetic separation (IMS) steps were investigated and an optimized method for detection of Cryptosporidium and Giardia in wastewater reclamation system was recommended in this paper. The experimental results show that an overnight soak of the membrane after scraping and vortex agitation before elution could enhance and stabilize the recovery. Increasing turbidity to 4 NTU by adding kaolin clay before filtration could effectively improve the recovery of low-turbidity water. Washing the concentrate after centrifugation and twice acid dissociation both reduced the impact of water quality to protozoan recovery. Protozoans in different water samples were determined by this optimized method, and the recovery of Cryptosporidium and Giardia were above 70% and 80% respectively, much higher than the acceptance of method-1623. __________ Translated from Environmental Science, 2006, 27(12): 2547–2552 [译自: 环境科学]     

Mortality rates of pathogen indicator microorganisms discharged from point and non-point sources in an urban area

This research measured the mortality rates of pathogen indicator microorganisms discharged from various point and non-point sources in an urban area.Water samples were collected from a domestic sewer,a combined sewer overflow,the effluent of a wastewater treatment plant,and an urban river.Mortality rates of indicator microorganisms in sediment of an urban river were also measured.Mortality rates of indicator microorganisms in domestic sewage,estimated by assuming first order kinetics at 20°C were 0.197 day -1 ,0.234 day -1 ,0.258 day -1 and 0.276 day -1 for total coliform,fecal coliform,Escherichia coli,and fecal streptococci,respectively.Effects of temperature,sunlight irradiation and settlement on the mortality rate were measured.Results of this research can be used as input data for water quality modeling or can be used as design factors for treatment facilities.     

南方某城市地表水体中粪源性污染指示微生物的分布特征研究

随着城市居民亲水娱乐活动日益增加,研究城市地表水体的粪源性微生物污染特征,开展人体健康风险评价,并以此为基础开展有效的水质监测和风险管理,对于人口密集的城市区域尤为重要.以我国南方某城市的5个典型地表水体为案例,监测总大肠菌（TC）、粪大肠菌（FC）、大肠埃希氏菌（EC）和肠球菌（ENT）这4种粪源性污染指示微生物以及常规理化水质指标,研究指示微生物在城市地表水体中的浓度水平、时间和空间分布特征以及不同水质指标之间的相关性.结果表明,案例水体中TC和FC通常在10^3～10^7个.L^-1,EC和ENT通常分别低于200个·L^-1和105个·L^-1;4种指示微生物的浓度分布呈现季节变化特征,并且能够指示水体受到周边环境的污染状况;4种指示微生物指标之间以及微生物指标与常规理化水质指标（如溶解氧等）之间具有一定的相关性.     

库湾营养盐循环对三峡库区营养盐输运的影响:以草堂河为例

三峡水库蓄水后,库区众多支流下游形成库湾回水区,这些库湾回水区是库区水环境调整最为活跃的地区.为了探究支流库湾对于库区生源要素循环及物质通量的作用和意义,于2012年8月~2013年7月对草堂河库湾、相邻干流、支流上游水体中溶解态无机氮(DIN)、溶解态无机磷(DIP)、溶解态硅酸盐(DSi)的时空分布进行逐月现场观测.结果表明,草堂河库湾回水区营养盐的浓度与库区干流相近,二者的月变化趋势也高度一致.干流输入是库湾DIN、DIP、DSi的主要来源.草堂河库湾与干流连通性很好,干支流水体交换迅速且充分,其影响可到达库湾回水区的末端.春、夏季,干流输入的营养盐通过表层生产力在库湾截留,秋、冬季库湾中的营养盐释放并输送到干流.营养盐在库湾的这种循环过程,在一定程度上改变了库区干流不同季节营养盐输送的节律.库区支流库湾众多,其对干流物质通量的季节调配作用不容忽视.     

三峡水库支流回水河段氮磷负荷与干流的逆向影响

通过分析三峡库区大宁河回水河段氮磷的来源、数量及时空特征,研究三峡水库成库初期和稳定运行期,次级支流回水段受干流的逆向影响.结果表明,成库初期,支流回水段的氮磷分配特征初步呈现干流逆向影响效应,分别有19.05%TN、28.93%TP源于干流倒灌输入;由于干流顶托作用,氮磷呈现具峰值的空间分布特征.在稳定运行期,支流回水段的氮磷来源及数量将明显受干流逆向影响,在其中的藻类适宜生长期,大宁河回水段干流倒灌输入的TN、TP分别高出上游径流输入近3倍、10倍,明显高于成库初期.当运行水位从145m升至175m时,支流回水段纳受干流倒灌输入的TN、TP可分别达15484.99、1185.75t.研究表明,干流逆向影响可能加剧三峡水库水体的富营养化.     

Determination of paraquat in water samples using a sensitive fluorescent probe titration method

Paraquat (PQ), a nonselective herbicide, is non-fluorescent in aqueous solutions. Thus, its determination through direct fluorescent methods is not feasible. The supramolecular inclusion interaction of PQ with cucurbit[7]uril was studied by a fluorescent probe titration method. Significant quenching of the fluorescence intensity of the cucurbit[7]uril-coptisine fluorescent probe was observed with the addition of PQ. A new fluorescent probe titration method with high selectivity and sensitivity at the ng/mL level was developed to determine PQ in aqueous solutions with good precision and accuracy based on the significant quenching of the supramolecular complex fluorescence intensity. The proposed method was successfully used in the determination of PQ in lake water, tap water, well water, and ditch water in an agricultural area, with recoveries of 96.73% to 105.77%. The fluorescence quenching values (ΔF) showed a good linear relationship with PQ concentrations from 1.0×10^-8 to 1.2× 10^-5 mol/L with a detection limit of 3.35×10^-9 mol/L. In addition, the interaction models of the supramolecular complexes formed between the host and the guest were established using theoretical calculations. The interaction mechanism between the cucurbit[7]uril and PQ was confirmed by ¹H NMR spectroscopy.     

污水再生处理系统中隐孢子虫和贾第鞭毛虫检测方法的优化

隐孢子虫和贾第鞭毛虫是2种严重危害水质安全的病原性原生动物.与USEPA1623方法相比,以膜过滤-洗脱法作为浓缩方式的检测流程回收率较高且成本较低.本研究通过对膜过滤-洗脱环节和免疫磁性分离(IMS)过程进行改进和参数优化,建立了适用于污水再生处理系统的两虫检测方法.研究发现,对滤膜进行刮擦处理后隔夜浸泡,以及洗脱前剧烈振荡等操作能够显著提高并稳定回收率.投加高岭土浊液提高水样的浊度至4NTU更加有效地提高了低浊水样的浓缩回收率.离心浓缩后洗涤沉淀并进行2次酸解离是降低IMS过程水质干扰的有效措施.采用该优化方法对不同来源水样进行检测,隐孢子虫回收率超过70%,贾第鞭毛虫回收率超过80%,明显高于1623方法的接受标准(>24%).     

三峡库区库中干流及支流水体夏季二氧化碳分压及扩散通量

以三峡库区库中干流以及主要支流——梅溪河为研究区,于2013年5月对该区域水体中溶解二氧化碳分压(pCO2)进行了走航观测.结果表明,夏季梅溪河表层pCO2为6.8~7.5 Pa,三峡库区库中长江干流表层pCO2为201.4~210.2 Pa.在库区干、支流交汇的过渡区水体剖面上,表层水体pCO2最低为53.5 Pa,随着水深增加,pCO2急剧增大,在3 m处达到约210Pa后基本保持不变.通过计算,库区支流梅溪河和库区干流表层水体的CO2释放通量分别为-7.48 mmol·(m2·d)-1和39.58 mmol·(m2·d)-1.结果表明,库区支流梅溪河表现为大气中CO2的"汇",而库区干流表现为CO2的"源",库区干、支流水体在CO2的释放上有显著差异.     

城市地表水中肠道病原微生物与粪便污染指示菌的关系研究

本研究选择肠道病毒、伤寒沙门氏菌、志贺氏菌、大肠埃希氏菌作为城市水体中典型的肠道病原微生物,分别建立起相应的实时荧光定量PCR检测方法.对水源水、景观娱乐用水以及城市河流样品进行长期监测,考察典型肠道病原微生物的分布特征和变化规律.肠道病毒在各地表水体中都有检出,浓度大都在103copy·L-1以下.大肠埃希氏菌的含量在保护良好的水体和接纳城市污水的水体中有明显差别,而伤寒沙门氏菌和志贺氏菌通常出现在受粪便污染较重的水体中.统计学的分析结果显示各种水体中的肠道病原微生物检出浓度均符合对数正态分布规律.粪便污染指示菌与肠道病毒之间不存在显著的相关性,但却能在一定程度上反映典型肠道病原菌的存在情况.在大肠菌群或粪大肠菌群浓度为104CFU·L-1以上的样品中,伤寒沙门氏菌、志贺氏菌具有较高的阳性率.     

黄河河口地区生态供水效益分析

流域生态需水是指流域生态系统为维持一定程度的生态系统健康所需要一定质量的水量,以保证流域生态系统结构和生态功能等为目标,实现流域生态系统健康。流域生态需水量的研究对于社会经济的可持续发展具有重要的战略意义。论文针对南水北调西线一期工程的供水规划,在提出配水效益计算方法的基础上,针对不同的配水量,计算了黄河河口地区的生态需水量、生态效益以及供水对减少断流所带来的生态效益,并进行了方案比较分析。主要结论是:当来水量分别为55×10⁸、122.8×10⁸或240×10⁸m³时,产生的湿地综合生态效益则为34.85×10⁸、47.18×10⁸或54.72×10⁸元。     

Efficient visible light photo-Fenton-like degradation of organic pollutants using in situ surface-modified BiFeO3 as a catalyst

The visible light photo-Fenton-like catalytic performance of BiFeO₃ nanoparticles was investigated using Methyl Violet (MV), Rhodamine B (RhB) and phenol as probes. Under optimum conditions, the pseudo first-order rate constant (k) was determined to be 2.21×10^-2, 5.56×10^-2 and 2.01×10^-2 min^-1 for the degradation of MV (30 μmol/L), RhB (10 μmol/L) and phenol (3 mmol/L), respectively, in the BiFeO₃-H₂O₂-visible light (Vis) system. The introduction of visible light irradiation increased the k values of MV, RhB and phenol degradation 3.47, 1.95 and 2.07 times in comparison with those in dark. Generally, the k values in the BiFeO₃-H₂O₂-Vis system were accelerated by increasing BiFeO₃ load and H₂O₂ concentration, but decreased with increasing initial pollutant concentration. To further enhance the degradation of pollutants at high concentrations, BiFeO₃ was modified with the addition of surface modifiers. The addition of ethylenediamineteraacetic acid (EDTA, 0.4 mmol/L) increased the k value of MV degradation (60 μmol/L) from 1.01×10^-2 min^-1 in the BiFeO₃-H₂O₂-Vis system to 1.30 min^-1 in the EDTA-BiFeO₃-H₂O₂-Vis system by a factor of 128. This suggests that in situ surface modification can enable BiFeO₃ nano-particles to be a promising visible light photo-Fenton-like catalyst for the degradation of organic pollutants.     

Photocatalytic degradation of Rhodamine B bymicrowave-assisted hydrothermal synthesized N-doped titanate nanotubes

Microwave-induced nitrogen-doped titanate nanotubes（NTNTs） were characterized by transmission electron microscopy（TEM）, X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）, Fourier transform infrared spectroscopy（FT-IR）, Zeta potential analysis,specific surface area（SBET）, and UV-Visible spectroscopy. TEM results indicate that NTNTs retain a tubular structure with a crystalline multiwall and have a length of several hundred nanometers after nitrogen doping. XRD findings demonstrate that the crystalline structure of NTNTs was dominated by anatase, which is favored for photocatalytic application. The Ti-O-N linkage observed in the XPS N 1s spectrum is mainly responsible for narrowing the band gap and eventually enhancing the visible light photoactivity. FT-IR results demonstrated the existence of H3O＋, which could be excited by photo-generated holes to form hydroxyl radicals and degrade environmental pollutants. After sintering at 350°C, the UV-Vis absorbance edges of NTNTs significantly shift to the visible-light region, which indicates N atom doping into the nanotubes. Photocatalytic degradation of Rhodamine B（RhB） via NTNTs show good efficiency, with pseudo first-order kinetic model rate constants of 3.7 × 10-3, 2.4 × 10-3and 8.0 × 10-4sec-1at pH 3, 7, and 11, respectively.     

三峡水库春季营养盐和浮游植物空间分布及其影响机制

为研究三峡水库春季水体营养盐与浮游植物的空间分布状况,于2013年3月对三峡水库22条支流及干流的6个断面进行采样监测. 结果表明:来水、回水、河口和干流4类断面ρ(TN)平均值分别为1.69、1.84、2.01、1.51 mg/L;ρ(TP)平均值分别为0.115、0.191、0.179和0.181 mg/L;不同类型断面间ρ(TN)、ρ(TP)差异不显著;水体中N、P的主要形态分别为NO₃--N和PO₄3--P;N/P〔n(N)/n(P)〕从来水(110.8)至干流(18.9)逐渐降低. 三峡水库总体上为中营养状态,回水和河口区富营养化程度较高,富营养断面比例分别为45.4%和36.4%. 研究期间共检出浮游植物8门98属,其中以绿藻门、硅藻门和蓝藻门为主,分别检出42、26和17属;从组成上看,来水和干流断面以硅藻-绿藻为主,回水、河口断面以绿藻-硅藻为主. 浮游植物丰度由高到低依次为回水、河口、来水和干流断面. 调查期间,22条支流中有15条支流在不同位置发生水华,但主要集中在回水区;拟多甲藻水华为主要类型且集中在库区的下游支流,而库区中上游支流则以隐藻、衣藻、小球藻、小环藻等水华为主. 环境因子排序分析表明,在水华集中的回水-河口区域,影响浮游植物丰度分布的主要环境因子数明显少于其他区域,温度和ρ(DO)为该区域浮游植物丰度分布的主要影响因子,而ρ(TN)、ρ(TP)的影响不明显.