催化光度法测定水中痕量亚硝酸根

基于亚硝酸根对溴酸钾氧化结果紫而使其褪色的催化作用,建立了灵敏的催化光度测定痕量亚硝酸根的新方法,测定范围为０．０２－０．１６μｇ／ｍＬ,用于水样中亚硝酸根的测定,获得了满意结果。     

环境水中污染物亚硝酸根的现场快速测定研究

通过研制一种环境保护试纸从而能简便快速地现场半定量测定环境水中污染物亚硝酸根,便于野外水环境普查,应用它可使测定时间由标准法的3h左右短到5min,使分析成本大为降低。     

天然水体中亚硝酸根和硝酸根的光化学研究进展

综述了近年来亚硝酸根和硝酸根 (NO-2 /NO-3 )在天然水体中的环境光化学研究进展。重点介绍了NO-2 /NO-3 光解生成活性氧 (如羟基 )的机理及其影响因素 ,探讨了NO-2 /NO-3 光解引发天然水体中有机物反应的环境意义 ,并据此提出了本领域今后的研究方向     

天然水体中亚硝酸根和硝酸根的光化学研究进展

综述了近年来亚硝酸根和硝酸根(NO2^-／NO3^-)在天然水体中的环境光化学研究进展。重点介绍了NO2^-／NO3^-光解生成活性氧(如羟基)的机理及其影响因素，探讨了NO2^-／NO3^-光解引发天然水体中有机物反应的环境意义，并据此提出了本领域今后的研究方向。     

中性红新分光光度法测定水中微量亚硝酸根

水中微量亚硝酸盐的分光光度法测定,最广泛应用的是Griess法。近20多年来,其它一些偶合试剂亦有过报导。光度法测定亚硝酸根除使用重氮偶合剂外,国外亦曾推荐过下列较有价值的试剂:2-乙氧-6,9-二氨基吖啶(雷佛奴尔、Rivanol)、巯基乙酸、硫脲[ Fe(Ⅲ)]、二甲马钱碱和邻—联甲苯胺。本文作者亦曾以雷佛奴尔为显色剂     

碱性过硫酸钾氧化-紫外分光光度法测水体总氮

碱性过硫酸钾氧化--紫外分光光度法所用消化剂K2S2O8在220nm处有很强的吸收峰，在消解过程中应确保其分解完全，否则即使其只有总量1%的残余，仍足以构成对比色测定的严重干扰。NaOH溶液在220nm处也有吸光度，但加盐酸中和后即减弱。消煮液的残余碱度对比色的干扰也可以同法消除。     

甲基橙分光光度法测定环境空气及工业废气中游离溴

以０．００５‰甲基橙溶液富集吸收,用分光光度法测定环境空气和工业废气中的游离溴,并对样品的采集、保存和最佳测定条件进行了研究。结果表明,方法的采样效率〉９７％,线性良好,精密度和准确度均较高,方法灵敏,按２０Ｌ采样体积计,方法的最低检出浓度为０．０２５ｍｇ／ｍ＾３。     

几种试剂对硝酸根光催化脱色甲基橙的影响

以NO^-₃为光催化剂,在紫外灯照射下,对甲基橙溶液进行光催化脱色。结果表明,叔丁醇、甲醇和乙醇对催化脱色反应有抑制作用; KBr和Na₂SO₄对脱色反应均有促进作用;而且KBr的加入量存在最佳值; Na₂SO₄的促进作用随Na₂SO₄的量的增加逐渐增强。Na₂CO₃的存在对甲基橙的脱色反应没有影响。K₂S₃O₈和NO^-₃之间存在较强的协同作用;KIO₃和NO^-₃之间存在相加作用;KBrO₃和NO^-₃之间存在拮抗作用。     

乙酰丙酮光度法测定甲醛方法的改进

用乙酰丙酮溶液将CODcr反应管制成标准反应管,CODcr消解器加热回流30min,DR／2010分光光度计比色测定甲醛含量。方法精密度、准确度满足甲醛测定的分析要求。     

紫外分光光度法测定水中丁基黄原酸

根据丁基黄原酸具有在301 nm紫外波长段有最大吸收峰,pH＜2时1 min内能够完全被分解,同时该吸收峰消失的特性,采用紫外分光光度(UV)法测定待测水样中丁基黄原酸浓度,并用待测水样作为背景校正,可有效地消除干扰.该方法的检出限为0.006 mg/L、测定上限为12.00 mg/L,实际水样测定的相对标准偏差小于5.76%.利用不同方法对样品进行分析测试,无明显差异.该方法具有线性相关性好、线性范围宽、操作简单准确等特点.     

Effect of dissolved oxygen concentration on nitrite accumulation in nitrifying sequencing batch reactor.

A mathematical model based on Activated Sludge Model No. 3 (International Water Association, London) and laboratory-scale experiments were used to investigate ammonia conversion by nitrification in a sequencing batch reactor (SBR). The purpose of the study was to assess the effect of dissolved oxygen concentration on nitrite accumulation in the SBR. As the dissolved oxygen concentration in the SBR depends on the balance between oxygen consumption and oxygen transfer rates, ammonium conversion was measured for different air flowrate values to obtain different dissolved oxygen concentration profiles during the cycle. The ammonia concentration in the feeding medium was 500 mg ammonium as nitrogen (N-NH4(+))/L, and the maximum nitrite concentration achieved during a cycle was approximately 50 mg nitrite as nitrogen (N-NO2)/L. The air flow supplied to the reactor was identified as a suitable parameter to control nitrite accumulation in the SBR. This identification was carried out based on experimental results and simulation with a calibrated model. At a low value of the volumetric mass-transfer coefficient (kLa), the maximum nitrite concentration achieved during a cycle depends strongly on k(L)a, whereas, at a high value of k(L)a, the maximum nitrite concentration was practically independent of kL(a).     

An intercomparison of formaldehyde measurement techniques at ambient concentration

A study was conducted to evaluate five techniques for determining ambient formaldehyde concentrations. One technique used a spectroscopic determination, and the other four techniques used derivatization followed by fluorometric analysis or high-performance liquid chromatography with detection by u.v. absorption. Formaldehyde was generated by two techniques. In the first technique, zero air was bubbled through a solution of aqueous formaldehyde to produce gas-phase formaldehyde. Various compounds serving as possible interferences were added singly or in combination to these air mixtures. In the second technique, formaldehyde was generated as a product from controlled irradiations of hydrocarbons and nitrogen oxides in a smog chamber operated in a dynamic mode. The study was conducted as a blind intercomparison with no knowledge by the participants of the HCHO concentrations or the interferences added.The data from each of the techniques were compared against mean values in each sampling period. For formaldehyde in zero air, average deviations for each of the techniques ranged between 15 and 30%. At a formaldehyde concentration of 10 ppb, each technique showed no evidence for interferences by O₃ (190 ppbv), NO₂ (300 ppbv), SO₂ (20 ppbv), and H₂O₂ (7 ppbv). The agreement for formaldehyde concentrations measured for the photochemical mixtures was similar to that of the mixtures in zero air.Ambient measurements were also performed on three evenings and for one 36-h period. Ambient formaldehyde concentrations ranged from 1 to 10 ppbv. Ambient H₂O₂ measurements were also performed. A strong correlation in the diurnal concentration profile for formaldehyde and H₂O₂ was observed over the 36-h period.     

Influence of photolysis on multispectral photoacoustic measurement of nitrogen dioxide concentration

Multispectral photoacoustic instruments are commonly used to measure aerosol and nitrogen dioxide (NO₂) light absorption coefficients to determine the radiation budget of the atmosphere. Here a new photoacoustic system is developed to explore the effect of photolysis on the measured signal in a multispectral photoacoustic spectrometer. In this system, a 405-nm laser is used primarily as light source for photolysis. Additionally, a well-overlapped 532-nm laser, modulated at the resonant frequency of the photoacoustic instrument, is used to probe the NO₂ concentration. As a result, the photolysis effect at 405 nm can be observed by the photoacoustic instrument through the 532-nm laser. This work determines an 11% reduction of the photoacoustic signal caused by the photolysis effect for typical conditions, which needs to be taken into account when calibrating multispectral photoacoustic spectrometers with NO₂.

Implications: Multispectral photoacoustic instruments are commonly used to measure aerosol and nitrogen dioxide (NO₂) light absorption coefficients to determine the radiation budget of the atmosphere. A 405-nm laser is often used in these multispectral photoacoustic instruments. Although NO₂ absorbs strongly at 405 nm, it also has a strong photolysis pathway that is accessible by light of the same wavelength. Photolysis reduces the photoacoustic signal, necessitating special care when interpreting photoacoustic measurements. This paper offers a method for the multispectral photoacoustic instrument user to quantify the influence of the 405-nm NO₂ photolysis effect on the photoacoustic signal.     

Estimation of atmospheric trace metal emissions in Vilnius City, Lithuania, using vertical concentration gradient and road tunnel measurement data

A new approach for the estimation of trace metal emissions in Vilnius city was implemented, using vertical concentration profiles in the urban boundary layer and road tunnel measurement data. Heavy metal concentrations were examined in fine and coarse particle fractions using a virtual impactor (cut-off size diameter 2.5 μm). Negative vertical concentration gradients were obtained for all metals (Ba, Pb, V, Sb, Zn) and both fractions. It was estimated that the vertical concentration gradient was formed due to emissions from an area of about 12 km². Road tunnel measurements indicated that trace metal concentrations on fine particles were lower than those on coarse particles, which suggested that re-emitted road dust was highly enriched in trace metal due to historic emissions within the tunnel. Emission rates of different pollutants in the road tunnel were calculated using pollutant concentration differences at the tunnel entrance and exit and traffic flow data. Heavy metal emission rates from the area of Vilnius city were estimated using the vertical gradient of heavy metal concentrations and the coefficient of turbulent mixing, as derived from meteorological measurement data. The emission values calculated by the two different methods coincided reasonably well, which indicated that the main source of airborne trace metals in Vilnius city is traffic. The potential of the vertical concentration gradient method for the direct estimation of urban heavy metal emissions was demonstrated.     

利用亚硝酸盐为电子受体反硝化聚磷菌的筛选与富集

依据DPB原理,利用SBR动态反应器和静态释/聚磷装置.以A2/O工艺厌氧段污泥为种泥,研究以亚硝酸盐为电子受体反硝化聚磷菌的筛选与富集,同时对选择、富集污泥的反硝化聚磷性能进行了考察.结果表明:利用亚硝酸盐为电子受体的反硝化聚磷菌存在于A2/O厌氧段污泥中,通过厌氧/好氧和厌氧/缺氧方式运行后,聚磷菌总数由1400个/mL增加到32 000个/mL,其中反硝化聚磷菌占聚磷菌总数的比例也由14.5%提高到81%,磷酸盐和亚硝酸盐去除率分别由最初的8.65%和7.55%上升到91%和95.62%;筛选与富集利用亚硝酸盐为电子受体的反硝化聚磷菌时,缺氧段进水COD的浓度须控制在10 mg/L以下;当体系处于稳定状态,且亚硝酸盐氮浓度高达30 mg/L时,并未对反硝化聚磷菌的生存产生抑制和体系运行产生干扰,此时磷酸盐出水低至1.06 mg/L.     

Comparison of two estimation methods for surface area concentration using number concentration and mass concentration of combustion-related ultrafine particles

Recent research has suggested that the adverse health effects caused by nanoparticles are associated with their surface area (SA) concentrations. In this study, SA was estimated in two ways using number and mass concentrations and compared with SA (SA_meas) measured using a diffusion charger (DC). Aerosol measurements were made twice: once starting in October 2002 and again starting in December 2002 in Mysore, India in residences that used kerosene or liquefied petroleum gas (LPG) for cooking. Mass, number, and SA concentrations and size distributions by number were measured in each residence. The first estimation method (SA_PSD) used the size distribution by number to estimate SA. The second method (SA_INV) used a simple inversion scheme that incorporated number and mass concentrations while assuming a lognormal size distribution with a known geometrical standard deviation. SA_PSD was, on average, 2.4 times greater (range = 1.6–3.4) than SA_meas while SA_INV was, on average, 6.0 times greater (range = 4.6–7.7) than SA_meas. The logarithms of SA_PSD and SA_INV were found to be statistically significant predictors of the logarithm of SA_meas. The study showed that particle number and mass concentration measurements can be used to estimate SA with a correction factor that ranges between 2 and 6.     

Uncertainty associated with the gravimetric measurement of particulate matter concentration in ambient air

This work applied a propagation of uncertainty method to typical total suspended particulate (TSP) sampling apparatus in order to estimate the overall measurement uncertainty. The objectives of this study were to estimate the uncertainty for three TSP samplers, develop an uncertainty budget, and determine the sensitivity of the total uncertainty to environmental parameters. The samplers evaluated were the TAMU High Volume TSP Sampler at a nominal volumetric flow rate of 1.42 m³ min^–1 (50 CFM), the TAMU Low Volume TSP Sampler at a nominal volumetric flow rate of 17 L min^–1 (0.6 CFM) and the EPA TSP Sampler at the nominal volumetric flow rates of 1.1 and 1.7 m³ min^–1 (39 and 60 CFM). Under nominal operating conditions the overall measurement uncertainty was found to vary from 6.1 x 10^–6 g m^–3 to 18.0 x 10^–6 g m^–3, which represented an uncertainty of 1.7% to 5.2% of the measurement. Analysis of the uncertainty budget determined that three of the instrument parameters contributed significantly to the overall uncertainty: the uncertainty in the pressure drop measurement across the orifice meter during both calibration and testing and the uncertainty of the airflow standard used during calibration of the orifice meter. Five environmental parameters occurring during field measurements were considered for their effect on overall uncertainty: ambient TSP concentration, volumetric airflow rate, ambient temperature, ambient pressure, and ambient relative humidity. Of these, only ambient TSP concentration and volumetric airflow rate were found to have a strong effect on the overall uncertainty. The technique described in this paper can be applied to other measurement systems and is especially useful where there are no methods available to generate these values empirically.

Implications:?This work addresses measurement uncertainty of TSP samplers used in ambient conditions. Estimation of uncertainty in gravimetric measurements is of particular interest, since as ambient particulate matter (PM) concentrations approach regulatory limits, the uncertainty of the measurement is essential in determining the sample size and the probability of type II errors in hypothesis testing. This is an important factor in determining if ambient PM concentrations exceed regulatory limits. The technique described in this paper can be applied to other measurement systems and is especially useful where there are no methods available to generate these values empirically.     

Improvement of odor intensity measurement using dynamic olfactometry

Odor intensity reveals a dose-effect relationship between inhaled odor and perceived odor sensation by the receptors, while odor concentration reflects the odor strength at the emission sources. The study reports significant improvements in experimental procedures in establishing the odor concentration-intensity (OCI) relationships using a newly developed digital olfactometer. The improvements in experimental procedures have been made to meet the requirements of both the VDI guideline 3882.1 and the European standard (EN13725). Several areas which could affect the reliability of the results have been identified in some similar studies. The latest digital olfactometer was calibrated automatically to ensure accurate and repeatable dilution ratios. Cross contamination has been eliminated through the instrument design and extensive cleaning procedures, making random presentation possible. Stringent panelist screening and continuous performance monitoring ensures consistent sensitivity of the panel. The extension of odor intensity category to temperature sensation gives a reference to assist judgments of perceived odor sensation. The DynaScent calculation method has simplified odor intensity calculation and can be applied to many odor samples. A total of 38 odor samples from three alumina refinery sites and two sewage treatment plants were collected for analysis. The results have confirmed the efficiency of the olfactometer. Distinct Odor Concentrations (DOCs) were calculated for each sample using both VDI and DynaScent methods. A student t test on two major odor types confirmed that there are no significant differences between two methods. The study has shown the DOCs for refinery odor and wastewater odor are in the range of 3.8-15.4 and 4.2-15.6 odor unit (OU)/m3 respectively. The study demonstrated that the improvements are critical in achieving reliable odor intensity measurement. This can lead to the setup of quantitative odor impact criteria for different industries and sites.     

碳源类型对以NO2-为电子受体短程反硝化过程的长期和短期影响

短程生物脱氮是未来污水生物处理的主流技术,其反硝化过程是实现氮去除的关键步骤。碳源类型是NO2-还原过程的重要因素之一,为选择适于以NO2-为电子受体的反硝化碳源,采用序批式反应器（SBR）,考察4种碳源（乙酸钠、甲醇、乙醇和生活污水）对NO2-为还原过程长期和短期影响。实验结果表明,微生物对不同碳源具有较强的适应性,经过一定时间的驯化,可明显提高微生物的反硝化能力,与未驯化时相比,还原速率分别提高3.1、2.1、1.7和2.4倍。培养初期,四种碳源条件下NO2-还原速率的大小关系为：r乙醇=1.3r乙酸钠=2.6r生活污水=3.8r甲醇。长期驯化稳定后,NO2-还原速率的大小关系为：r乙酸钠=1.4r乙醇=2.6r生活污水=4.3r甲醇。此外,经过驯化后,微生物可适应较高的pH值,增强抵抗pH波动的能力。当存在多种碳源时,微生物优先利用已驯化碳源。4种碳源中,乙酸钠最容易被微生物利用,还原速率为40.7 mg·（g·h）-1,而甲醇较难被微生物利用,其还原速率为26.2 mg·（g·h）-1。     

PM_(2.5)手工标准方法与自动监测法比对分析

选取金华、衢州、温州、丽水、宁波、杭州6个城市开展PM2.5手工标准方法和自动监测法比对实验,并用相关性和相对偏差两个指标对比对结果进行分析和评价。结果表明:(1)2013年6个采样城市采集的PM2.5手工和自动监测值均具有较好的相关性(相关系数均在0.95以上),截距均在-0.010~0.010mg/m3,但斜率相差较大(衢州和丽水在0.90以上;金华、温州和杭州在0.85~0.90;宁波在0.80以下)。(2)2013年6个城市采集的PM2.5手工和自动监测值的相对偏差为-34.2%~36.5%;PM2.5手工和自动监测值相对偏差在±15%范围内的数据占总数据量的82.6%;负偏差数据占总数据量的80.0%。(3)PM2.5手工标准方法和自动监测法的比对差异与地域、季节和PM2.5浓度等条件有关。总体上,不同地区PM2.5手工与自动监测值相对偏差绝对值(︱RD︱)年平均值为衢州丽水金华宁波温州杭州;春季PM2.5手工与自动监测值︱RD︱平均值高于夏季,秋季高于冬季;各采样城市PM2.5手工和自动监测值︱RD︱平均值在高质量浓度(PM2.5手工监测值(ρ1)0.150mg/m3)下最小,中质量浓度(0.050≤ρ1≤0.150mg/m3)下最大,低质量浓度(ρ10.050mg/m3)下介于两者之间。