A Study of Sorptive Loss Patterns for Reduced Sulfur Compounds in the Use of the Bag Sampling Method

In this work, the basic properties of the bag sampling method were examined and characterized in terms of recovery rate with respect to four reduced sulfur compounds (RSC) including H₂S, CH₃SH, DMS, and DMDS. For this comparative study, two types of calibration approaches were performed to evaluate the relative RSC loss due to bag sampling. As a reference calibration tool, a syringe dilution (SD) method was applied. The working standards prepared by diluting the primary standard in a gas-tight syringe (as a mixing chamber) were injected to the GC/PFPD through a loop-injection system to yield a background calibration information. In contrast, the target calibration was performed based on a bag dilution (BD) method. To this end, working standards for multiple calibration points were prepared by two different bag types (Tedlar bag (TB) and polyester bag (PB)). These standards were then drawn by the same syringe and injected into the GC/PFPD via loop. On the basis of these comparative analyses, both absolute and relative differences in RSC recovery rates (RR) were evaluated (e.g., comparison of wall-loss effect). The results indicate that TB has a mean RR of 87% for the four RSC with their values ranging from 82 (CH₃SH) to 91% (DMDS). On the other hand, the results of PB generally exhibited slightly reduced RR with their mean values of 77% (range: 73% of H₂S to 83% of DMS). The results of this study generally suggest that the losses of RSC samples, while inevitable with the bag sampling method, exhibit certain patterns between different RSCs and between different grab sampling materials.     

Reduced sulfur compounds in ambient air surrounding an industrial region in Korea

The atmospheric concentrations of several reduced sulfur compounds (RSCs) including H(2)S, CH(3)SH, DMS, CS(2), and DMDS were measured concurrently from a series of field campaigns covering multiple locations in the surroundings of a large industrial region (August 2004 to September 2005). These field studies have been designed and undertaken to inspect the concentrations of RSCs in ambient air. The RSC concentrations were found to occur in a highly variable range. H(2)S (1.06 +/- 2.07 ppb) was found to be the most abundant RSC followed by CS(2) (0.84 +/- 0.54 ppb), DMDS (0.36 +/- 1.21 ppb), DMS (0.24 +/- 0.83 ppb), and CH(3)SH (0.11 +/- 0.23 ppb). The RSC levels measured at the study area were comparable to those observed previously from other polluted environmental settings. When these RSC data were examined further in terms of spatial (industrial vs. non-industrial sites) and seasonal (summer vs. winter seasons) grouping schemes, differences in their concentration levels were statistically insignificant in most cases. In contrast, there were fairly strong variations in temporal patterns over a diurnal cycle. If these RSC concentration data were converted to diagnose the malodor strengths, their effects were in most cases insignificant with minor contribution towards odor nuisances.     

Characteristics of malodor pollutants and aromatic VOCs around an urban valley in Korea

In this study, the environmental behavior of malodor pollutants (MPs) [including reduced sulfur compounds (RSCs)] and aromatic volatile organic compounds (AVOCs) were investigated around urban valley areas during several field campaigns (February through December 2006). The MPs measured in the study area include the RSCs (H(2)S, CH(3)SH, DMS, and DMDS), ammonia (NH(3)), and styrene (STY); the AVOCs include benzene (BEN), toluene (TOL), ethylbenzene (EB), m,p-xylene (MPX), and o-xylene (OX). The variation of most MP concentrations (except for DMDS) was found to be larger than that of AVOCs. It was found that STY (2,346 +/- 4,867 ppbv) was the most dominant MP followed by NH(3) (447 +/- 285), CH(3)SH (16 +/- 41), and the others (<8). The magnitude of AVOCs was found in the following descending order: TOL (1.4 +/- 2.2 ppbv), EB (1.0 +/- 2.1), MPX (0.9 +/- 2.0), and the others (<0.8). The concentration levels of most MPs on industrial (I) and downwind (D) sites were up to an order of magnitude higher than those at non-industrial (N) and upwind (U) sites. For most AVOCs, the former was ~3 times higher than the latter. For malodor intensity in RSCs, CH(3)SH was the dominant contributor. The concentration difference in target compounds between the sites/periods is likely to be caused by the combined effects such as emission sources, geographical features (e.g., semi-closed topography), and meteorological conditions (e.g., wind directions) in and outside the urban valley.     

大气痕量有机硫化物的光电离色谱法测定及硫酸铵在湿浸土壤中释放有机硫化物的研究

采用国产光电离色谱仪(GC-PID)对有机硫化物:乙基硫醇,二甲基硫,二甲基二硫进行了分离分析,其最小检知量在亚微克/升级,并对北京郊区的某些天然源环境样品进行了有机硫化物浓度的测定,实验数据证实,在鸡场,猪场,水稻田与塑料蔬菜大棚等环境大气中含有机硫化物。研究了硫酸铵作为氮肥加入到水浸土壤中后,由于缺氧而生成有机硫化物的现象,观察了其对有机硫化物的释放规律及硫酸铵与葡萄糖分别作为硫源与碳源对有机硫化物生成的影响,实验结果认为:硫酸铵在五种不同类型的水浸土壤中(环境温度25℃),均可解离释放出有机硫化物,随其在土壤中加入量的增多,释放气中的有机硫浓度增加,二甲基硫的释放量最大。     

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.     

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。     

气质联用法测定环境空气中有机硫化物

采用 SUMMA罐采集空气样品，在预浓缩系统中经3级冷阱捕集后，用气相色谱-质谱联用技术测定环境空气中7种痕量有机硫化物。对试验条件进行优化，使得甲硫醇、乙硫醇、甲硫醚、二硫化碳、噻吩、乙硫醚和二甲二硫醚等7种有机硫化物在21．47μg/m3～336．43μg/m3范围内线性良好。试验表明，7种有机硫化物的方法检出限为0．004μg/m3～0．036μg/m3；标准气体平行测定6次结果的 RSD为2．7％～6．2％，加标回收率为92．2％～97．5％。用该方法测定实际空气样品，并与傅立叶红外光谱法测定的结果进行比对，结果令人满意。     

Empirical gas emission and oxidation measurement at cover soil of dumping site: example from Malaysia

Methane (CH₄) is one of the most relevant greenhouse gases and it has a global warming potential 25 times greater than that of carbon dioxide (CO₂), risking human health and the environment. Microbial CH₄ oxidation in landfill cover soils may constitute a means of controlling CH₄ emissions. The study was intended to quantify CH₄ and CO₂ emissions rates at the Sungai Sedu open dumping landfill during the dry season, characterize their spatial and temporal variations, and measure the CH₄ oxidation associated with the landfill cover soil using a homemade static flux chamber. Concentrations of the gases were analyzed by a Micro-GC CP-4900. Two methods, kriging values and inverse distance weighting (IDW), were found almost identical. The findings of the proposed method show that the ratio of CH₄ to CO₂ emissions was 25.4 %, indicating higher CO₂ emissions than CH₄ emissions. Also, the average CH₄ oxidation in the landfill cover soil was 52.5 %. The CH₄ and CO₂ emissions did not show fixed-pattern temporal variation based on daytime measurements. Statistically, a negative relationship was found between CH₄ emissions and oxidation (R ²?=?0.46). It can be concluded that the variation in the CH₄ oxidation was mainly attributed to the properties of the landfill cover soil.     

硫化学发光检测器-气相色谱法测定废气中挥发性硫化物

采用硫化学发光检测-宽口径石英毛细管柱气相色谱法,建立了废气中羰基硫、硫化氢、二硫化碳、甲硫醇、乙硫醇、甲硫醚、乙硫醚、丙硫醇、异丙硫醇、噻吩及二甲二硫等11种挥发性硫化物的分析方法。硫化学发光检测器的灵敏度、选择性及线性范围均优于传统的火焰光度检测器。进样体积为0.2 ml时,硫化物的检出限为0.03～0.1 mg/m3。实际样品5次测定的相对标准偏差小于5.1%,加标回收率为83.7%～108.8%。测定了某炼油厂酸性水罐尾气、污油罐尾气及瓦斯气中挥发性硫化物,为其恶臭控制与治理提供检测手段和基础数据。     

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。