A wide range of compounds with various structural features can cause taste and odor(TO)problems in drinking water. It would be desirable to determine all of these compounds using a simple analytical method. In this paper, a sensitive method combining liquid–liquid extraction(LLE) with gas chromatography-triple quadrupole tandem mass spectrometry(GC–MS/MS)was established to simultaneously analyze 51 odor-causing compounds in drinking water,including organic sulfides, aldehydes, benzenes, phenols, ethers, esters, ketones, nitrogenous heterocyclic compounds, 2-methylisoborneol and geosmin. Three deuterated analogs of target analytes, dimethyl disulfide-d6, benzaldehyde-d6 and o-cresol-3,4,5,6-d4,were used to correct the variations in recovery, and five isotope-labeled internal standards(4-chlorotoluene-d4, 1, 4-dichlorobenzene-d4, naphthalene-d8, acenaphthene-d10, phenanthrene-d10 respectively) were used prior to analysis to correct the variations arising from instrument fluctuations and injection errors. The calibration curves of the target compounds showed good linearity(R2 0.99, level = 7),and method detection limits(MDLs) below 1/10 of the odor threshold concentrations were achieved for most of the odorants(0.10–20.55 ng/L). The average recoveries of most of the analytes in tap water samples were between 70% and 120%, and the method was reproducible(RSD 20%, n = 7). Additionally, concentrations of odor-causing compounds in water samples collected from three drinking water treatment plants(DWTPs) were analyzed by this method.According to the results, dimethyl trisulfide, dimethyl disulfide and indole were considered to be the key odorants responsible for the swampy/septic odor. 2-Methylisoborneol and geosmin were detected as the main odor-causing compounds for musty/earthy odor in DWTP B. 相似文献
Global environmental change places unavoidable pressure on water resources and agronomic crop production systems. Irrigation development is a credible measure to alleviate the challenge of food safety under water shortages, but it needs sufficient basis. The aim of this study is to address the problem of balancing water scarcity with food requirements, which are the key components of water security in regions with population growth. Marginal water productivity (MWP) indices for irrigation water performance and productivity evaluation were established in the current study. Based on the analysis of the regional water-crop relationship and spatial differences of MWP in China, the priorities for developing irrigation areas in different types of regions are discussed in this study. The results show that high MWPs are mainly in semi-arid regions with precipitation (P) between 500 and 1000 mm, while low MWPs mostly occur in areas with P more than 1000 and less than 500 mm. The significance and spatial distribution patterns of MWP are different than those of conventional irrigation water use efficiency evaluation indices, so its role cannot be replaced for the real production capacity of irrigation water evaluation. The strategies for global environmental change adaptation suggested in this study are taking MWP for irrigation water productivity evaluation and the priority irrigation schemes for agronomic crop determination; increasing MWP by means of irrigation efficiency and crop variety improvement worldwide; and raising global food production through the expansion of irrigation area in the regions hold high MWP and abundant water resources.
Distribution of PCDD/F (polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran) congeners at two electric arc furnaces (EAFs) in Taiwan is evaluated via intensive stack sampling and analysis. Two kinds of exhaust system in EAFs including stack system and shutter system are selected for measuring dioxin emissions. In addition, dioxin emissions during oxidation and reduction stages at EAF-A were characterized. Results indicate that the PCDD/F concentration of stack gas in EAF-A was 4.39 ng/N m3 while total Toxic Equivalent Quantity (TEQ) concentration was 0.35 ng I-TEQ/N m3. The PCDD/F concentration of stack gas in EAF-B was 2.20 ng/N m3 and the TEQ concentration was 0.14 ng I-TEQ/N m3. 1,2,3,4,6,7,8-HpCDF, OCDD and OCDF are the major contributors of the dioxin concentrations for two EAFs investigated and the percentage of PCDD/F in particulate phase increases as the chlorination level of the PCDD/F congener increases. The results obtained on gas/particulate partitioning of PCDD/Fs in flue gases prior to the APCD in EAFs indicate that more than 90% exists in particulate phase. In EAF-A, the PCDD/F concentration during oxidation stage is slightly higher than that measured during reduction stage, including the sampling points of CO converter outlet, prior to bag filter and stack. Majority of PCDD/Fs emitted from steel-making processes exists in particulate-phase (about 60–70%) at both EAFs investigated. 相似文献
