分光光度法测定废水中草甘膦的探讨

探讨了亚硝基衍生化紫外分光光度法测定废水中草甘膦的适用性,考察了硫酸加入体积对亚硝化反应的影响,提出应根据样品碱度调整硫酸用量。方法与高效液相色谱法测定值的重现性较好,应用于实际废水中草甘膦测定的加标回收率为95%～105%,平行测定的RSD≤1.3%,检出限为0.069 mg/L,检测上限为50.0 mg/L,废水中可能存在的伯胺和叔胺类物质对测定无明显干扰。     

气相色谱法同时测定水中28种多氯联苯单体

采用液液萃取-浓硫酸磺化净化-气相色谱电子捕获检测器同时测定水中28种多氯联苯单体,必要时利用质谱选择离子监测模式定性,考察了萃取溶剂种类和体积及盐析效应对测定的影响,比较了硫酸磺化和弗罗里硅土柱对萃取液的净化效果。方法在1.00μg/L~47.6μg/L范围内线性良好,当取样体积为200 mL时,方法检出限为0.001μg/L~0.002μg/L,基体加标回收率为95.8%~103%,相对标准偏差≤18.7%。     

工作场所空气中硫酸雾（SO3）的分析

采用碘量法测定工作场所空气中的三氧化硫及硫酸雾，三氧化硫及硫酸雾经中性水吸收后与碘化钾和碘酸钾反应，析出的碘与淀粉指示剂作用产生蓝色，进行比色测定。     

Some phenolic compounds of extracts obtained from Origanum species growing in Turkey

Caffeic acid, rosmarinic acid, rutin, apigenin 7-O-glucoside, apigenin, and acesetin were the main phenolic compounds of Origanum onites extracts in all applications. While acesetin contents ranged from 133.59 mg/100 g (U1) to 437.25 mg/100 g (S3), rosmarinic acid changed between 215.94 mg/100 g (U4) and 1120.56 mg/100 g (S2) in Origanum vulgare L. subsp. hirtum (Link) Ietsw. Both rosmarinic acid and acesetin were not found in U5 application. Only caffeic acid (19.39 mg/100 g) was found in U5 application. Rosmarinic acid contents of O. onites extract changed between 158.62 mg/100 g (U5) and 799.87 mg/100 g (S2). Generally, dominant phenolic compound of Origanum extracts was rosmarinic acid compared with other extracts. In addition, methanol:water:acetic acid mixture (S2) (95:4.5:0.5) was found as the best application. Phenolic contents of extracts obtained with U series mixtures were found low.     

Factor analysis of H2S emission at a wastewater lift station: a case study

Odor and corrosion are common problems in domestic wastewater collection, transportation, pumping, and treatment processes. Based on the comparison among odorous compounds and onsite observations at a wastewater lift station, H₂S is more likely to have caused the odor and corrosion problems than methanethiol and other organic sulfides. The field data from both air and wastewater quality monitoring demonstrated that more H₂S (1 ppmv) was formed at a more negative redox potential, lower pH, and a higher temperature of wastewater. Since the lower detection level of most current analytical techniques is much greater than human’s smell and the reference concentration for adverse health effects, automatic monitoring on the threshold of H₂S formation provides a mechanism to trigger control techniques only when necessary for cost saving purposes. Based on Gibbs free energy, a more negative redox potential is required to form H₂S with an increase in pH and a decrease in temperature and SO ₄ ^2? concentration. However, pH effect is more significant than both temperature and SO ₄ ^2? concentration for H₂S formation. It is recommended that H₂S control techniques be started when the redox potential is below ?44 mV, the pH is lower than 5.6, and the temperature is higher than 11.5 °C to control H₂S below the reference concentration. Corroded concrete particles were examined by X-ray diffraction, which showed that the dominant crystal form was quartz.     

硫酸雾测试方法若干问题思考

简述了我国硫酸雾测试方法的发展历史,分析和总结了《固定污染源废气硫酸雾的测定离子色谱法》(HJ 544—2016)存在的一些争议和问题,包括硫酸雾的定义、测试方法的干扰控制等。分析认为,相比《硫酸工业污染物排放标准》(GB 26132—2010),HJ 544—2016对硫酸雾的定义更加合理。实验结果表明:硫酸盐是测试方法条件下的目标物,滤筒可以显著地捕捉硫酸盐。9组样品滤筒中,被测目标物所占比例为7.9%~69.1%;滤筒和前吸收液中,被测目标物所占比例为93.7%~97.8%。HJ 544—2016新增加的两级串联碱液吸收瓶可以较完全地捕集穿透滤筒后的硫酸雾,同时也会捕集SO2。SO2会对硫酸雾测试产生正干扰,约42.9%的SO2在被吸收后转化为硫酸雾。     

A new catalytic-spectrophotometric method for quantification of trace amounts of nitrite in fruit juice samples

A new kinetic method has been developed for the determination of nitrite in fruit juice samples. The method is based on the catalytic effect of nitrite with the oxidation of Nile Blue A (NBA) by KBrO₃ in the sulfuric acid medium. The optimum conditions obtained are 1.2 mM sulfuric acid, 0.034 mM of NBA, 2.8?×?10^?3 M KBrO₃, reaction temperature of 20 °C, and reaction time of 100 s at 595.5 nm. Under the optimized conditions, the method allowed the quantification of nitrite in a range of 0.2–800 μg/mL with a detection limit of 0.02 μg/mL. The method was applied to the determination of nitrite in 15 brands of fruit juice samples.     

土壤和沉积物中多氯联苯单体测定的净化方法研究

对浓硫酸净化、铜粉脱硫、氟罗里硅土柱、硅胶柱、石墨碳柱等净化方法在土壤和沉积物多氮联苯单体测定中的应用进行了研究.浓硫酸对多氯联苯单体的净化回收率达92.4％～109％;氟罗里硅土柱用正己烷/丙酮混合溶液淋洗,净化洗脱液体积为8 mL～10 mL时,回收率达85.7％ ～ 108％;硅胶柱用正己烷淋洗,净化洗脱液体积为...     

The role of sample surveys for monitoring the condition of the nation's lakes

In order to meet a growing need to determine the condition of the nation's ecosystems and how their condition is changing, the U.S. Environmental Protection Agency (EPA) developed EMAP, the Environmental Monitoring and Assessment Program. A common survey design serves as the foundation on which to base monitoring of status and trends among diverse ecosystem types. In this paper, we describe the need for a statistically based survey design, briefly summarize the basic EMAP design, describe how that design is tailored for the selection of a probability sample of lakes on which to make measurements of lake condition, and illustrate the process for selecting a sample of lakes in the northeastern United States. Finally, we illustrate how measurements taken on the sample of lakes can be summarized, with known uncertainty, to describe the condition of a population of lakes.The U.S. Government right to retain a non-exclusive, royalty free licence in and to any copyright is acknowledged.     

固相微萃取-气相色谱法测定水中痕量甲萘威

建立了固相微萃取-气相色谱法测定水中痕量甲萘威的方法,并对固相微萃取条件进行了优化。结果显示,固相萃取的最佳条件为:水样pH值≤3,不添加无机盐,聚二甲基硅氧烷(PDMS,100μm)作为萃取纤维,萃取温度为80℃,萃取时间为30 min,解吸时间为90 s。优化后的方法,在甲萘威质量浓度0.01~1.0 mg/L范围内线性良好,相关系数为0.999 5,方法的精密度为1.9%,检出限为0.3μg/L,加标回收率为85.6%~92.4%,可满足地表水中甲萘威的测定要求。     

Evolution of water chemistry in natural acidic environments in Yangmingshan,Taiwan

In Yangmingshan National Park, located in the northern part of the Taiwan Island, there is a very rare area where fish (Channa asiatica) live in spite of acid environments. The origin of the acid in local acid ponds and rivers and the evolution of the water chemistry are discussed on the basis of sulfur stable isotope ratios and chemical equilibria. One of the sources of the acid is sulfuric acid, which is derived from the oxidation of hydrogen sulfide in volcanic gas gushing out from fumaroles around the area and from acid deposition supplied from Taipei City. It is also derived from the oxidation of pyrite: the sulfur stable isotope ratios of delta 34S of +1@1000 to +4@1000 (relative to CDT) of sulfate in acid pond waters (pH 3-4) could be related to those of hydrogen sulfide in volcanic gas, pyrite in local pond sediments and soils, and sulfate in rain water. One acid source is sulfuric and hydrochloric acids arising in springs from geothermal activity: the delta 34S values were characterised by +13@1000 to +17@1000 sulfate-S, which was provided by a disproportionation reaction of sulfur dioxide in the depths. Another acid source could be the oxidation of iron(II). Under acidic conditions, the water-rock reaction gives rise to high concentrations of aluminium and iron. While flowing down surface streams, iron(II) is oxidised to iron(III) and then hydrolysed to cause further acidification under oxic conditions. The concentrations of iron and aluminium are controlled by redox and dissolution equilibria.     

电导返滴定法测定苯酚含量

向苯酚试液中加入定量过量的ＮａＯＨ标准溶液,用Ｈ３ＢＯ３标准溶液滴定过量的ＮａＯＨ,通过计算求得苯酚含量,测定下限为１０－５ｍｏｌ／Ｌ。并成功地测定了某化工厂废液中苯酚含量。     

Water quality status of dugouts from five districts in Northern Ghana: implications for sustainable water resources management in a water stressed tropical savannah environment

This study was primarily aimed at investigating the physicochemical and microbial quality of water in 14 such dugouts from five districts in the northern region of Ghana. Results obtained suggest that except for colour, turbidity, total iron and manganese, many physicochemical parameters were either within or close to the World Health Organisation’s acceptable limits for drinking water. Generally, colour ranged from 5 to 750 Hz (mean 175 Hz), turbidity from 0.65 to 568 nephelometric turbidity units (NTU; mean 87.9 NTU), total iron from 0.07 to 7.85 mg/L (mean 1.0 mg/L) and manganese from 0.03 to 1.59 mg/L (mean 0.50 mg/L). Coliform counts in water from all the dugouts in both wet and dry seasons were, however, above the recommended limits for drinking water. Total and faecal coliforms ranged from 125 to 68,000 colony forming units (cfu)/100 mL (mean 10,623 cfu/100 mL) and <?1 to 19,000 cfu/100 mL (mean 1,310 cfu /100 mL), respectively. The poor microbial quality, as indicated by the analytically significant presence of coliform bacteria in all samples of dugout water, strongly suggests susceptibility and exposure to waterborne diseases of, and consequent health implications on, the many people who continuously patronise these vital water resources throughout the year. In particular, more proactive sustainable water management options, such as introduction to communities of simple but cost-effective purification techniques for water drawn from dugouts for drinking purposes, education and information dissemination to the water users to ensure environmentally hygienic practices around dugouts, may be needed.     

水样中痕量十溴联苯醚的分散液-液微萃取条件的优化

采用正交设计和Box-Penhnken响应面设计,对分散液-液微萃取技术萃取水样中痕量十溴联苯醚的条件进行了筛选和优化,得到最佳条件:四氯乙烯为萃取剂(10μl)、丙酮作分散剂(1ml)、pH范围5~9、离子强度,2%NaCl及萃取时间10min。此优化条件下分散液-液微萃取技术的萃取回收率可达92.37%~104.38%,富集倍数为508~611。优化条件下方法的线性范围为0.01~100ng/ml,检出限(S/N=2)为3.0pg/ml,加标回收率为96.25%~102.16%,精密度为5.44%~6.34%。     

土壤中总氰化物分析方法的研究

通过对底泥、土壤中氰化物预处理方法的选择,证明在硫酸介质中蒸馏,用氢氧化钠为吸收液,异烟酸吡唑啉酮光度法测定土壤中总氰化物的分析方法具有准确度高、精密度好等特点。     

An automatic monitor of formaldehyde in air by a monitoring tape method

An automatic monitor has been developed for measuring formaldehyde in air using a sensitive tape for formaldehyde. It is based on the color change of the tape on reaction with formaldehyde. The porous cellulose tape, containing silica gel as an absorbent and impregnated with the processing solution containing hydroxylamine sulfate, Methyl Yellow (pH indicator; pH 2.9-4.0, red-yellow), glycerin and methanol, was found to be a highly sensitive means of detecting formaldehyde and maintains a stable sensitivity. When the tape was exposed to a sample of air containing formaldehyde, the color of the tape changed from yellow to red. The degree of color change was proportional to the concentration of formaldehyde at a constant sampling time and flow rate, and it could be recorded by measuring the intensity of reflected light (555 nm). The tape could be used to detect down to 0.08 ppm (World Health Organization standard) of formaldehyde with a sampling time of 30 min and a flow rate of 100 mL min-1. Reproducibility tests showed that the relative standard deviation of response (n = 10) was 3.8% for 0.1 ppm formaldehyde. The monitor is simple, specific, capable of unattended operation and is recommended for both laboratory and field operation.     

Monitoring Inter-Annual Variability Reveals Sources of Mercury Contamination in Clear Lake, California

Mercury (Hg) in the aquatic ecosystem of Clear Lake has been documented since the 1970s when fishes were found to have elevated levels of toxic methyl mercury (meHg). Mining practices at the Sulphur Bank Mercury Mine (active intermittently from 1872–1957) along the shoreline of Clear Lake included the bulldozing of waste rock and overburden ore into the shallow nearshore regions of the lake and the creation of steeply sloped piles of waste rock at the water's edge. This process, plus erosion of the waste rock piles, resulted in the accumulation of an estimated 100 metric tons of Hg in Clear Lake. A monitoring program to assess Hg in Clear Lake was established in 1992, and conducted continuously from 1994. Drought conditions in California had persisted for ca. 6 yrs prior to 1992, when the U.S. Environmental Protection Agency (USEPA) remediated the steeply sloped eroding waste rock piles, which appeared to reduce sediment Hg concentrations significantly. In April 1995, a white flocculent material was observed in Clear Lake adjacent to the mine and has been observed every year since, leading to the discovery of ongoing acid mine drainage (AMD), low pH fluids high in Hg and extremely high in sulfate. AMD is now believed to be the most likely cause of elevated meHg in Clear Lake. The discovery of this source of meHg production in Clear Lake, which will significantly influence remedial options, was only made possible by implementation of a diligent monitoring program.     

Determination of hydrogen peroxide in workplace air: interferences and method validation

A dynamic system for the generation of stable hydrogen peroxide test atmospheres was applied to the evaluation of samplers used for the determination of hydrogen peroxide in workplace air. The system is able to generate gas mixtures of between 0.1 and 10 ppm at different combinations of relative humidity (20-80%) and temperature (10-30 degrees C). Gaseous hydrogen peroxide is sampled on glass filters impregnated with Ti(IV) chloride and sulfuric acid and analyzed by UV spectroscopy. An interference was observed due to the acid catalyzed decomposition of peroxyacetic acid to hydrogen peroxide. This was significantly reduced by applying high sample flow rates and by lowering the concentration of sulfuric acid. The performance of the sampler and sources of uncertainties were tested according to the European Standard EN 1076.     

Efficiency of Modified H2S Test for Detection of Faecal Contamination in Water

Faecal contamination is a major causative factor for incidence of water borne infectious diseases. Certain hydrogen sulfide (H₂S) producing enteric bacteria such as Salmonella sp. and Citrobacter sp., assosiated with coliforms, have been considered for rapid detection of recent faecal contamination in water. The basic H₂S test medium, modified by adding 0.25 gm/L of L-cystine HCl, was examined for its efficiency with 90 water samples collected from 40 pipe supplies, 20 open wells, 15 hand pumps and 15 different surface water bodies (river, streams and ponds). Sterilized modified culture medium in glass vials was inoculated with 100 mL of each sample and incubated at 20, 25, 30, 35 and 44 ^∘C for 18, 24, 42, 48, 66 and 72 h. Blackening of content in incubated vials was considered positive. For comparison, most probable number (MPN) of coliform and faecal coliform per 100 mL was also estimated in each sample by multiple tube fermentation (MTF) method. H₂S positive result was exhibited by 78% of samples. Coliform (> 10) and faecal coliform/100 mL were also detected in 59% of samples. Maximum H₂S positive results (100%) were found with well and surface water samples incubated at 30, 35 and 44 ^∘C for 18 h. Coliform (> 10) and faecal coliform/100 mL were also detected in most of these samples. Pipe supplies (60%) and hand pumps (73%) also exhibited considerable H₂S production. Coliforms and faecal coliforms were also found in significant number of these samples. Thus, the modified H₂S test may prove a useful alternative indicator of faecal contamination for water quality surveillance and screening of large number of water samples in short duration, particularly during any outbreak of water borne disease among rural population.     

一种新型微生物絮凝剂的制备及对Cu2+去除性能的探究

以城市污水处理厂的脱水污泥为原料,通过超声波细胞破碎制备微生物絮凝剂。采用控制变量法考察污泥浓度、超声波破碎时间对絮凝剂絮凝效果的影响,并探究絮凝液的投加量、pH值、温度、振荡时间、振荡频率、共存金属等因素对5 mg/L Cu^2+模拟废水的去除效果,分析了微生物絮凝剂去除Cu^2+的作用机理。结果表明:当污泥质量浓度为100 g/L,超声波破碎时间15 min时,絮凝剂的絮凝效果最好;当pH值为6.5,温度50℃,絮凝液投加量40 mL,振荡时间1 min,振荡频率200 r/min时去除效果最佳。