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Le Nguyen Truc Thinh Nguyen An Ha Nguyen Thi Vinh Tien Nguyen Dinh Lam Nguyen Duc Hong Nguyen Van Tuan Nguyen Tat Hanh Ta Van Khanh Nguyen Ngoc Thanh Nguyen Ngoc Hens Luc 《Environment, Development and Sustainability》2022,24(10):12427-12445
Environment, Development and Sustainability - The recent growth of agriculture, industry and urban areas in Vietnam requires a large amount of water consumption as a production factor. This paper... 相似文献
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Monitoring of benzene, toluene and xylenes (BTEX) was conducted along with traffic counts at 17 roadside sites in urban areas of HoChiMinh. Toluene was the most abundant substance, followed by p,m-xylenes, benzene, o-xylene and ethylbenzene. The maximum observed hour-average benzene concentration was 254 μg/m3 . Motorcycles contributed to 91% of the traffic fleet. High correlations among BTEX species, between BTEX concentrations and the volume of on-road motorcycles, and between inter-species ratios in air and in gasoline indicate the motorcycle-exhaust origin of BTEX species. Daily concentrations of benzene, toluene, ethylbenzene, p,m-xylenes and o-xylene were 56, 121, 21, 64 and 23 μg/m 3 , respectively. p,m-xylenes possess the highest ozone formation potential among the BTEX family. 相似文献
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Huynh Ngoc Phien Anat Arbhabhirama 《Journal of the American Water Resources Association》1980,16(5):856-861
ABSTRACT: The effects of the selections of plotting position formulae and class division schemes on goodness of fit tests are investigated for the extreme-value type-1 distribution using annual flood and annual maximum daily rainfall data. It was found that the plotting position formulae have a minor influence on the tests which involve their use, while the class division schemes may have a pronounced effect on the X2-test. The study also recommended the maximum likelihood method for fitting purposes and a new test which is independent of the afore-mentioned selections for judging the goodness of fit. 相似文献
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Huynh Ngoc Phien M. Ayub Khan 《Journal of the American Water Resources Association》1981,17(6):1035-1041
ABSTRACT: Two autoregressive models for monthly stream flow generation are compared based on the reproduction of the historical record in terms of several important statistics such as the mean, standard deviation, skewness coefficient, correlation coefficient, and the reservoir storage components. In the comparison, both theoretical considerations and practical applications are employed to evaluate the performance of each model. 相似文献
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Huynh Ngoc Phien Apichai Sunchindah Debabrata Patnaik 《Journal of the American Water Resources Association》1982,18(1):37-42
ABSTRACT: Assessment of normality of hydrological data has been based upon subjective judgments. This paper aims to provide an objective method for such an assessment by introducing three computationally simple statistical tests. Application to some stream flow data indicates that (1) for annual values, at least one of the three sequences- original, square root, and logarithmic - can be considered to be normally distributed; and (2) most monthly stream flows are skew and neither the square root nor the logarithmic transformation is able to render their sequences in all the 12 months normal. 相似文献
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In a laboratory-scale combustion reactor, flue-gas samples were collected at two temperatures in the post-combustion zone, 700 °C and 400 °C, using two different water-cooled sampling probes. The probes were the cooled probe described in the European Standard method EN-1948:1, referred to as the original probe, and a modified probe that contained a salt/ice mixture to assist the cooling, referred to as the sub-zero probe. To determine the efficiency of the cooling probes, internal temperature measurements were recorded at 5 cm intervals inside the probes. Flue-gas samples were analyzed for polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs). Samples collected at 700 °C using the original cooling probe showed higher concentrations of PCDD/Fs compared to samples collected using the sub-zero probe. No significant differences were observed between samples collected at 400 °C. The results indicated that artifact formation of PCDD/Fs readily occurs during flue-gas sampling at high temperatures if the cooling within the probe is insufficient, as found for the original probe at 700 °C. It was also shown that this problem could be alleviated by using probes with an enhanced cooling capacity, such as the sub-zero probe.Although this may not affect samples collected for regulatory purposes in exit gases, it is of great importance for research conducted in the high-temperature region of the post-combustion zone. 相似文献
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Detection of dicofol and related pesticides in human breast milk from China, Korea and Japan 总被引:1,自引:0,他引:1
Fujii Y Haraguchi K Harada KH Hitomi T Inoue K Itoh Y Watanabe T Takenaka K Uehara S Yang HR Kim MY Moon CS Kim HS Wang P Liu A Hung NN Koizumi A 《Chemosphere》2011,82(1):25-31
Previously, we demonstrated that the concentrations of DDTs were greater in breast milk collected from Chinese mothers than from Japanese and Korean mothers. To investigate dicofol as a possible source of the DDTs in human breast milk, we collected breast milk samples from 2007 to 2009 in China (Beijing), Korea (Seoul, Busan) and Japan (Sendai, Takarazuka and Takayama). Using these breast milk samples, we quantified the concentrations of dichlorobenzophenone, a pyrolysis product of dicofol (simply referred to as dicofol hereafter), dichlorodiphenyltrichloroethane and its metabolites (DDTs) using GC-MS. Overall, 12 of 14 pooled breast milk samples from 210 mothers contained detectable levels of dicofol (>0.1 ng g−1 lipid). The geometric mean concentration of dicofol in the Japanese breast milk samples was 0.3 ng g−1 lipid and significantly lower than that in Chinese (9.6 ng g−1 lipid) or Korean breast milk samples (1.9 ng g−1 lipid) (p < 0.05 for each). Furthermore, the ΣDDT levels in breast milk from China were 10-fold higher than those from Korea and Japan. The present results strongly suggest the presence of extensive emission sources of both dicofol and DDTs in China. However, exposure to dicofol cannot explain the large exposure of Chinese mothers to DDTs because of the trace levels of dicofol in the ΣDDTs. In the present study, dicofol was confirmed to be detectable in human breast milk. This is the first report to identify dicofol in human samples. 相似文献
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Arsenic in groundwaters of the Lower Mekong 总被引:1,自引:0,他引:1
Stanger G Truong TV Ngoc KS Luyen TV Thanh TT 《Environmental geochemistry and health》2005,27(4):341-357
Increasing incidence and awareness of arsenic in many alluvial aquifers of South-east Asia has raised concern over possible
arsenic in the Lower Mekong Basin. Here, we have undertaken new research and reviewed many previous small-scale studies to
provide a comprehensive overview of the status of arsenic in aquifers of Cambodia and the Cuu Long Delta of Vietnam. In general
natural arsenic originates from the Upper Mekong basin, rather than from the local geology, and is widespread in soils at
typical concentrations of between 8 and 16 ppm; (dry weight). Industrial and agricultural arsenic is localised and relatively
unimportant compared to the natural alluvial arsenic. Aquifers most typically contain groundwaters of no more than 10 μg L−1, although scattered anomalous areas of 10 to 30 μg L−1 are also quite common. The most serious, but possibly ephemeral arsenic anomalies, of up to 600 μg L−1, are associated with iron and organic-rich flood-plain sediments subject to very large flood-related fluctuations in water
level, resulting in transient arsenopyrite dissolution under oxidizing conditions. In general, however, high-arsenic groundwaters
result from the competing interaction between sorption and dissolution processes, in which arsenic is only released under
reducing and slightly alkaline conditions. High arsenic groundwaters are found both in shallow water-tables, and in deeper
aquifers of between 100 and 120 m depth. There is no evidence of widespread arsenicosis, but there are serious localised health-hazards,
and some risk of low-level arsenic ingestion through indirect pathways, such as through contaminated rice and aquaculture.
An almost ubiquitous presence of arsenic in soils, together with the likelihood of greatly increased groundwater extraction
in the future, will require continuing caution in water resources development throughout the region. 相似文献