High-performance liquid chromatography method for determination of hydrogen peroxide in aqueous solution and application to simulated Martian soil and related materials

A new method for determination of hydrogen peroxide (H₂O₂) is described. H₂O₂ reacts with iodide in the presence of ammonium molybdate and vanillic acid resulting in the formation of iodovanillic acid which is quantified by reversed-phase high-performance liquid chromatography (HPLC) and detected by UV absorption at 280 nm. The method provides a detection limit of ～0.1 μM and is easy to implement. Iodovanillic acid is stable, allowing multiple measurements of the same sample, and the separation power of the HPLC yields high selectivity against potential interferences. This method will be useful for many environmental applications. The method has been applied to quantify the photochemical production of H₂O₂ by aqueous suspensions of various minerals and soils.     

Short-term Distributions of Reduced Sulfur Compounds in the Ambient Air Surrounding a Large Landfill Facility

In order to explore the environmental behavior of reduced sulfur compounds (RSC) as malodorous components emitted from diverse source processes, the distribution characteristics of four sulfur (S) compounds - hydrogen sulfide (H₂S), methyl mercaptan (CH₃SH), dimethyl sulfide (DMS: (CH₃)₂S), and dimethyl disulfide (DMDS: (CH₃)₂S₂) – were investigated in a municipal landfill area. In the course of this study, their ambient concentration levels were measured during two time periods from 13 individual spots selected as a function of distance from the center of the landfill site. The results generally indicated the absolute dominance of H₂S over the other S compounds investigated (up to 5 km radius) such that their mean values were found as 1415 (H₂S), 148 (DMS), 20.6 (CH₃SH), and 14.4 ppt (DMDS). When our data were compared in terms of either varying distance from the source or relationship with meteorological conditions, the H₂S data sets were most evident to reflect the potential effects of strong source processes in the landfill environment, relative to other S gases (or to volatile organic compounds measured concurrently). The results of this study further indicated the relatively good correspondence between the measured H₂S concentration level and humans' intuitive sensory of odor and nuisance.     

垃圾渗滤液中微塑料分析的消解方法评价

微塑料(MPs)是近年来国内外关注度极高的新兴污染物,建立实际环境样品中MPs的分析方法是开展相关研究的基础。对于复杂污水样品而言,样品的消解过程至关重要,将极大地影响MPs的准确分析。选择垃圾渗滤液为典型复杂污水样品,采用样品浊度和色度变化、残余悬浮固体量、MPs在颗粒物中的占比为评价指标,对盐酸消解、30%过氧化氢消解及芬顿试剂消解3种常用消解方法的消解效果进行了比较。结果表明,30%过氧化氢对垃圾渗滤液样品的消解效果最佳,MPs在全部颗粒物中的占比达63.7%,极大地缩减了后续MPs定性分析的时间,降低了分析难度,且对渗滤液中MPs的回收率也高达(103±3)%。在此基础上,讨论了消解效果与过氧化氢投加量/样品浊度(V_H2O2/T₁)的关系。当V_H2O2/T₁为0.15～0.20 mL/NTU时,样品残余悬浮固体量最低,消解效果最佳。     

便携式气相色谱测定固定源排气中的硫化氢

在SO₂与H₂S共存下,利用便携式气相色谱法测定了固定污染源排气中硫化氢含量。方法简便快速,准确度和精密度较高,受干扰物质二氧化硫的影响小,测定结果完全满足复杂成分烟气中硫化氢的测定要求。     

Hydrogen Peroxide and Ultraviolet Irradiations in Water Treatment

Trihalomethanes (THMs) the by-products of chlorination in water treatment are recognised as a threat to public health due to their carcinogenicity. The photodegradation of THMs using hydrogen peroxide has been found to give increased removal efficiency and the outcome of the study may find, its application in designing a unit process for water treatment. Batch experiments were carried out using UV lamp of 83 W and 40% w/w Hydrogen peroxide (H₂O₂) in test waters between 2.5–10 pH range of chloroform, bromodichloromethane, dibromochloromethane and bromoform at 50–200 μg L⁻¹ initial concentration. 92–100% removal of chloroform, bromodichloromethane, dibromochloromethane and bromoform were found with 0.1% of H₂O₂ and 90 min of UV exposure.     

Distribution, correlation, and source apportionment of selected metals in tannery effluents, related soils, and groundwater—a case study from Multan, Pakistan

The short-term responses of H₂O₂-depletion-related parameters in moss Hypnum plumaeforme to the combined stress induced by Pb and Ni were investigated. The results showed that the Pb and Ni stress induced dose-dependent accumulation of hydrogen peroxide (H₂O₂). The increase of peroxidase (POD) activity and decrease of ascorbate peroxidase (APX) activity were observed under the combined heavy metal application. The antioxidants, ascorbate (AsA) and proline content, increased significantly when the metals were applied together. The study indicated that the cell damage caused by Pb stress was higher than that caused by Ni stress, Pb and Ni had synergistic effect in inducing the oxidative stress in moss H. plumaeforme, especially under the combination of high concentration of Ni (0.1 and 1.0 mM) and Pb. Content of proline, H₂O₂ and the activity of POD, all showed a dose-dependent increase under Pb and Ni stress, suggesting their practical value as biomarkers in moss biomonitoring, especially in the case of light pollution caused by heavy metals without the changes in the appearance of mosses.     

Ambient hydrogen sulphide levels at a wastewater treatment plant

This paper describes a novel technique of measuring ambient hydrogen sulphide (H₂S) concentrations simultaneously at several locations around a wastewater treatment plant. A commercially purchased H₂S monitor is modified to operate in a static mode to enable degree of darkening on pieces of lead acetate tapes to be correlated againts the exposure duration and the ambient H₂S concentration of sewage air. The technique can yield mapped contours of time—average H₂S concentrations as low as 0.2 ppm. The methodology is exemplified for a wastewater treatment plant in Ipswich, Queensland. Isopleths of H₂S concentration obtained at the wastewater site for two different meteorological conditions reveal that high levels of H₂S are detected around the plant's inlet structure and primary clarifiers.     

Odour emission characteristics of 22 recreational rivers in Nanjing

The odour emission characteristics of 22 recreational rivers in Nanjing were investigated and analysed. Eight odorous compounds (ammonia (NH₃), hydrogen sulphide (H₂S), sulphur dioxide (SO₂), carbon disulphide (CS₂), nitrobenzene (C₆H₅NO₂), aniline (C₆H₅NH₂), dimethylamine (C₂H₇N), and formaldehyde (HCHO)) were measured in odour emission samples collected using a custom-made emission flux hood chamber. The results showed that all odorants were detected in all monitoring rivers. NH₃ was the main odorant, with emission rates ranging from 4.86 to 15.13 μg/min m². The total odour emission rate of the Nan River, at 1 427.07 OU/s, was the highest of the all investigated rivers. H₂S, NH₃ and nitrobenzene were three key odour emission contributors according to their contributions to the total odour emission. A correlation analysis of the pollutants showed there was a significant positive correlation between the emission rate of NH₃ and the concentration of ammonia nitrogen (NH₄ ⁺-N) and total nitrogen (TN). The H₂S and SO₂ emission rates had a significant positive correlation with sulphides (S^2?) and available sulphur (AS) in the water and sediment. The content of TN, NH₄ ⁺-N, S^2? and AS in the water and sediment affected the concentration of H₂S, SO₂ and NH₃ in the emission gases. NH₄ ⁺-N, S^2? and AS are suggested as the key odour control indexes for reducing odours emitted from these recreational rivers. The study provides useful information for effective pollution control, especially for odour emission control for the recreational rivers of the city. It also provides a demonstrate example to show how to monitor and assess a contaminated river when odour emission and its control need to be focused on.     

固定污染源废气中三氧化硫测试方法初探

建立了异丙醇吸收-分光光度法测试固定污染源中三氧化硫(SO_3)的方法,分别连续9次测试低、中、高3个质量浓度的SO_3烟气。测试结果表明,相对误差分别为7. 5%,-2. 6%和6. 7%,相对标准偏差分别为3. 3%,1. 7%和4. 1%,方法的准确度和精密度较好。方法检出限为0. 1 mg/m~3,测定下限为0. 4 mg/m~3。二氧化硫(SO_2)、一氧化碳(CO)、氮氧化物(NO_x)、硫化氢(H_2S)、含湿量、烟尘等因素对方法的干扰较小,方法适用于现场测试。     

Entrapping of organic wastes by coordination clathrates

The feasibility of the Hofmann clathrates Ni(CN)₂(NH₃)·G(G=guest molecule) and the octahedral Werner-type complexes Ni(X)₂(L)₄ (X=NCS, NCO, CH₃CO₂, C₆H₅CO₂; L=Py, 4-Mepy) as a scavenger for organic substrates in a polluted aqueous or organic medium is dependent on the complex lability, thermal stability and reversibility in solvent trapping which can be conveniently studied by thermogravimetric means. Besides the parent monomeric octahedral complexes, all the thermal decompositional intermediates, namely, monomeric tetrahedral, dimeric octahedral and polymeric octahedral, are also potential scavengers for selected organic substances though they operate via a cycle of bond-making and bond-breaking processes.     

Gastro-enteric methane versus sulphate and volatile fatty acid production

The breakdown of low digestible components present in food during passage through the human and animal gastro-intestinal (GI) tract is performed by the highly diverse microbial community present in this ecosystem. Fermentation of these substances yields, besides CO₂ and volatile fatty acids, H₂, which is used as a substrate by three different H₂-consuming bacteria. Sulphate-reducing bacteria (SRB) use H₂ to reduce SO _inf4 ^sup2- to H₂S, hydrogenotrophic methane-producing bacteria (MPB) use H₂ to reduce CO₂ to CH₄ and reductive acetogens (RAC) use H₂ to reduce CO₂ to CH₃COOH. A competition between these three bacterial groups exists for the common H₂ substrate. This results generally in the dominance of one group above the other two.     

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.     

Toxicity assessment of textile effluents treated by advanced oxidative process (UV/TiO2 and UV/TiO2/H2O2) in the species Artemia salina L.

Textile industry wastes raise a great concern due to their strong coloration and toxicity. The objective of the present work was to characterize the degradation and mineralization of textile effluents by advanced oxidative processes using either TiO₂ or TiO₂/H₂O₂ and to monitor the toxicity of the products formed during 6-h irradiation in relation to that of the in natura effluent. The results demonstrated that the TiO₂/H₂O₂ association was more efficient in the mineralization of textile effluents than TiO₂, with high mineralized ion concentrations (NH ₄ ⁺ , NO ₃ ^? , and SO ₄ ^2? ) and significantly decreased organic matter ratios (represented by the chemical oxygen demand and total organic carbon). The toxicity of the degradation products after 4-h irradiation to Artemia salina L. was not significant (below 10 %). However, the TiO₂/H₂O₂ association produced more toxicity under irradiation than the TiO₂ system, which was attributed to the increased presence of oxidants in the first group. Comparatively, the photogenerated products of both TiO₂ and the TiO₂/H₂O₂ association were less toxic than the in natura effluent.     

Monitoring of Fogwater Chemistry in the Gulf Coast Urban Industrial Corridor: Baton Rouge (Louisiana)

Seventeen fog events were sampled in Baton Rouge, Louisiana during 2002–2004 as part of characterizing wet deposition by fogwater in the heavily industrialized corridor along the Louisiana Gulf Coast in the United States. These samples were analyzed for chemical characteristics such as pH, conductivity, total organic and inorganic carbon, total metals and the principal ion concentrations. The dominant ionic species in all samples were NH₄⁺, NO₃⁻, Cl⁻ and SO₄²⁻. The pH of the fogwater sampled had a mean value of 6.7 with two cases of acidic pH of 4.7. Rainwater and fogwater pH were similar in this region. The acidity of fogwater was a result of NO₃⁻ but partly offset by high NH₄⁺. The measured gaseous SO₂ accounted for a small percentage of the observed sulfate concentration, indicating additional gas-to-particle conversion of SO₂ to sulfate in fogwater. The gaseous NO_x accounted for most of the dissolved nitrate and nitrite concentration in fogwater. The high chloride concentration was attributable to the degradation of chlorinated organics in the atmosphere. The metal composition was traced directly to soil-derived aerosol precursors in the air. The major metals observed in fogwater were Na, K, Ca, Fe, Al, Mg and Zn. Of these Na, K, Ca and Mg were predominant with mean concentrations > 100 μM. Al, Fe and Zn were present in the samples, at mean concentrations < 100 μM. Small concentrations of Mn (7.8 μM), Cu (2 μM), Pb (0.07 μM) and As (0.32 μM) were also observed in the fogwaters, and these were shown to result from particulates (PM_2.5) in the atmosphere. The contribution to both ions and metals from the marine sources in the Louisiana Gulf Coast was minimal. The concentrations of all principal ionic species and metals in fogwater were 1–2 orders of magnitude larger than in rainwater. Several linear alkane organic compounds were observed in the fogwater, representing the contributions from petroleum products at concentrations far exceeding their aqueous solubility. A pesticide (atrazine) was also observed in fogwater, representing the contribution from the agricultural activities nearby.     

Factors affecting metribuzin retention in Algerian soils and assessment of the risks of contamination

Metribuzin is a widely used herbicide around the world but it could lead to soil and water contamination. Metribuzin retention on a silty–clay agricultural soil of Algeria was studied in laboratory batch experiments to assess the contamination risk of the groundwater. Factors conditioning the fate of metribuzin were investigated: soil nature, metribuzin formulation, NPK fertilizer, and soil pH. Freundlich sorption isotherms gave the coefficients K _F between 1.2 and 4.9 and 1/n _a between 0.52 and 0.93. The adsorption is directly dependent on organic and clay soil contents. Formulated metribuzin (Metriphar) reduces the adsorption (K _F?=?1.25) compared to pure metribuzin (K _F?=?2.81). The addition of an NPK fertilizer decreases the soil pH (6.67 for the soil without fertilizer and 5.86 for 2 % of fertilizer) and increases metribuzin adsorption (K _F is 4.83 for 2 % of fertilizer). The pH effect on the adsorption is corroborated in experiments changing the soil pH between 5 (K _F is 4.17) and 8 (K _F is 1.57) under controlled conditions. Desorption isotherms show a hysteresis and only 30 to 40 % of the initially adsorbed metribuzin is released. The estimated GUS index is ≥2.8 for a DT50?≥?30 days. K _F values and the hysteresis show that metribuzin is little but strongly retained on the soil. Formulated metribuzin and addition of fertilizer affect the retention. However, the GUS index indicates a high mobility and a significant risk of leaching. The most appropriate risk management measure would be an important increase in organic matter content of the soil by addition of organic amendments.     

Assessment of six Indian cultivars of mung bean against ozone by using foliar injury index and changes in carbon assimilation, gas exchange, chlorophyll fluorescence and photosynthetic pigments

Six Indian cultivars of Vigna radiata L. (HUM-1, HUM-2, HUM-6, HUM-23, HUM-24 and HUM-26) were exposed with ambient and elevated (ambient + 10 ppb ozone (O₃) for 6 h?day^?1) level of O₃ in open top chambers. Ozone sensitivity was assessed by recording the magnitude of foliar visible injury and changes in various physiological parameters. All the six cultivars showed visible foliar symptoms due to O₃, ranging 7.4 to 55.7 % injured leaf area. O₃ significantly depressed total chlorophyll, photosynthetic rate (Ps), quantum yield (F _v/F _m) and total biomass although the extent of variation was cultivar specific. Cultivar HUM-1 showed maximum reduction in Ps and stomatal conductance. The fluorescence parameters also indicated maximum damage to PSII reaction centres of HUM-1. Injury percentage, chlorophyll loss, Ps, F _v/F _m and total biomass reduced least in HUM-23 depicting highest O₃ resistance (R%).     

UV/H2O2 oxidation of arsenic and terbuthylazine in drinking water

Arsenic is a widespread contaminant in the environment. The intake of water containing high concentrations of arsenic could have serious impact on human health, such as skin and lung cancer. In the European Union, thus, also in Italy, the arsenic limit in drinking water is 10 μg L^?1. Several water remediation treatment technologies are available for arsenic removal. For some processes, the removal efficiencies can be improved after an oxidation step. Most full-scale applications are based on conventional oxidation processes for chemical micropollutant removal. However, if water contains arsenic and refractory organic contaminants, the advanced oxidation processes could be considered. The aim of this work was to investigate the effectiveness of ultraviolet (UV) radiation alone and in combination with hydrogen peroxide for the oxidation of arsenic and terbuthylazine (TBA). The experimental tests were performed in groundwater at the laboratory scale (0.1 mg L^?1 As(III) and 10 μg L^?1 TBA). Hydrogen peroxide alone (15 mg L^?1) was ineffective on both arsenic and TBA oxidation; the 253.7-nm radiation alone did not oxidize arsenic(III), but photolyzed efficiently TBA (52 % removal yield at a UV dose of 1,200 mJ cm^?2). The UV/H₂O₂ advanced oxidation (UV dose 600–2,000 mJ cm^?2, 5–15 mg L^?1 H₂O₂) was the most effective process for the oxidation of both arsenic and TBA, with observed oxidation efficiencies of 85 and 94 %, respectively, with 5 mg L^?1 H₂O₂ and a UV dose of 2,000 mJ cm^?2.     

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.     

Measurement of sulphur gases in ambient air

A gas chromatograph with a flame photometric detector is set up for the direct analysis of COS, H₂S, CS₂, SO₂, CH₃SH, C₂H₅SH in ambient air.Logarithmic transformation is used to counterbalance the non-linear nature of the detector response for the individual sulphur gases. A quality assurance procedure is described to compensate any variation of response during field measurement. The use of Tedlar bags for sampling COS, CS₂, CH₃SH, C₂H₅SH is acceptable despite the general conception that sulphur gases are unstable in Tedlar bags.     

气质联用法测固定污染源中三氟甲烷、四氟甲烷、六氟乙烷和六氟化硫

建立了固定污染源排气中三氟甲烷、四氟甲烷、六氟乙烷和六氟化硫的采样和气质联用分析方法,检出限分别为0.06、0.15、0.21、0.71 mg/m3,精密度在3.2%以下,相关系数大于0.999 6,并对浙江省内2家典型企业排放的温室气体进行了监测,实际样品监测结果表明,该方法能够满足废气中4种温室气体的监测要求。