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751.
Levels of perfluorochemicals in water samples from Catalonia,Spain: is drinking water a significant contribution to human exposure? 总被引:2,自引:0,他引:2
Ericson I Nadal M van Bavel B Lindström G Domingo JL 《Environmental science and pollution research international》2008,15(7):614-619
Background, aim, and scope In recent years, due to a high persistence, biomagnification in food webs, presence in remote regions, and potential toxicity,
perfluorochemicals (PFCs) have generated a considerable interest. The present study was aimed to determine the levels of perfluorooctane
sulfonate (PFOS), perfluorooctanoic acid (PFOA), and other PFCs in drinking water (tap and bottled) and river water samples
from Tarragona Province (Catalonia, Spain).
Materials and methods Municipal drinking (tap) water samples were collected from the four most populated towns in the Tarragona Province, whereas
samples of bottled waters were purchased from supermarkets. River water samples were collected from the Ebro (two samples),
Cortiella, and Francolí Rivers. After pretreatment, PFC analyses were performed by HPLC-MS. Quantification was done using
the internal standard method, with recoveries between 68% and 118%.
Results In tap water, PFOS and PFOA levels ranged between 0.39 and 0.87 ng/L (0.78 and 1.74 pmol/L) and between 0.32 and 6.28 ng/L
(0.77 and 15.2 pmol/L), respectively. PFHpA, PFHxS, and PFNA were also other detected PFCs. PFC levels were notably lower
in bottled water, where PFOS could not be detected in any sample. Moreover, PFHpA, PFHxS, PFOA, PFNA, PFOS, PFOSA, and PFDA
could be detected in the river water samples. PFOS and PFOA concentrations were between <0.24 and 5.88 ng/L (<0.48 and 11.8 pmol/L)
and between <0.22 and 24.9 ng/L (<0.53 and 60.1 pmol/L), respectively.
Discussion Assuming a human water consumption of 2 L per day, the daily intake of PFOS and PFOA by the population of the area under evaluation
was calculated (0.78–1.74 and 12.6 ng, respectively). It was found that drinking water might be a source of exposure to PFCs
as important as the dietary intake of these pollutants.
Conclusions The contribution of drinking water (tap and bottled) to the human daily intake of various PFCs has been compared for the first
time with data from dietary intake of these PFCs. It was noted that in certain cases, drinking water can be a source of exposure
to PFCs as important as the dietary intake of these pollutants although the current concentrations were similar or lower than
those reported in the literature for surface water samples from a number of regions and countries.
Recommendations and perspectives Further studies should be carried out in order to increase the knowledge of the role of drinking water in human exposure to
PFCs. 相似文献
752.
Samaratunga SS Nishimoto J Tabata M 《Environmental science and pollution research international》2008,15(1):27-30
BACKGROUND, AIMS AND SCOPE: Chromium enters into the aquatic environment as a result of effluent discharge from steel works, electroplating, leather tanning industries and chemical industries. As the Cr(VI) is very harmful to living organisms, it should be quickly removed from the environment when it happens to be contaminated. Therefore, the aim of this laboratory research was to develop a rapid, simple and adaptable solvent extraction system to quantitatively remove Cr(VI) from polluted waters. METHODS: Aqueous salt-solutions containing Cr(VI) as CrO4(2-) at ppm level (4-6 ppm) were prepared. Equal volumes (5 ml) of aqueous and organic (2-PrOH) phases were mixed in a 10 ml centrifuge tube for 15 min, centrifuged and separated. Concentrations of Cr(VI), in both the aqueous and organic phases, were determined by atomic absorption spectrometry. The effects of salt and acid concentrations, and phase-contact time on the extraction of Cr(VI) were investigated. In addition, the extraction of Cr(VI) was assessed in the presence of tetramethylammonium chloride (TMAC) in 2-PrOH phase. Effects of some other metals, (Cd(II), Co(II), Cu(II), Ni(II) and Zn(II)), on the extraction of Cr(VI) were also investigated. RESULTS AND DISCUSSION: The Cr(VI) at ppm level was extracted quantitatively by salting-out the homogeneous system of water and 2-propanol(2-PrOH) using chloride salts, namely CaCl2 or NaCl, under acidic chloride media. The extracted chemical species of Cr(VI) was confirmed to be the CrO3Cl-. The ion-pair complex extracted into the organic phase was rationalized as the solvated ion-pair complex of [2-PrOH2+, CrO3Cl-]. The complex was no longer stable. It implied the reaction between extracted species. Studies revealed that salts and acid directly participated in the formation of the above complex. Use of extracting agents (TMAC) didn't show any significant effect on the extraction of Cr(VI) under high salting-out conditions. There is no significant interference effect on the extraction of Cr(VI) by the presence of other metals. The Cr(VI) in the organic phase was back-extracted using an aqueous ammonia solution (1.6 mol dm(-3)) containing 3 mol dm(-3) NaCl. The extraction mechanism of Cr(VI) is also discussed. CONCLUSIONS: Salting-out of homogeneous mixed solvent of 2-propanol can be employed to extract Cr(VI) quantitatively, as an ion-pair of [2-PrOH2+ * CrO3Cl-] solvated by 2-PrOH molecules. Then, the complex becomes 'solvent-like' and is readily separated into the organic phase. The increase of Cl- ion concentration in the aqueous phase favors the extraction. The 2-PrOH, salts and acid play important roles in the extraction process. There is no need to use an extracting agent at a high salting-out condition. RECOMMENDATIONS AND PERSPECTIVES: Chromium(VI) must be quickly removed before it enters into the natural cycle. As the 2-PrOH is water-miscible in any proportion, ion-pairing between 2-PrOH2+ and CrO3Cl- becomes very fast. As a result, Cr(VI) can easily be extracted. Therefore, the method is recommended as a simple, rapid and adaptable method to quickly separate Cr(VI) from aqueous samples. 相似文献
753.
水质总氮测定中的有关问题探讨 总被引:1,自引:0,他引:1
对总氮测定中的一系列影响因素,诸如实验用水,器皿的洗涤,实验室环境试剂的提纯、配制和保存,消解温度、压力和时间的控制,以及高氨氮水样中的总氮测定、总氮、总磷的同时测定和其他有关的问题,作了较为详细的探讨,并提出了相应的解决办法。 相似文献
754.
吸力式桶形基础多桶组合结构承载力特性研究 总被引:1,自引:0,他引:1
海洋采油平台结构中一般采用多桶组合基础型式,然而迄今对多桶组合结构尚缺乏理论分析和实验研究。本文针对我国第一座吸力式桶形基础采油平台CB20B,基于单桶基础在复合加载模式下的承载力特性,建立了双桶、四桶组合基础的三维有限元数值计算模型,探讨了对称多桶基础结构与单桶基础结构的承载力特性之间的相互关系,阐述了不同桶间距的多桶组合结构地基破坏机制,为工程设计提供参考依据。 相似文献
755.
采用弹塑性有限元分析方法,分析了悬臂式排桩支护的基坑开挖对邻近地基条形基础下极限承载力的影响性状。主要考虑了在基坑开挖深度、荷载与基坑的距离、荷载宽度、支护刚度等因素的影响下地基极限承载力的减损性状。研究表明,基坑开挖深度H较浅时,对地基极限承载力P_u的影响较小,P_u随H的增大略有降低,随着开挖深度的增加,H对P_u值的影响显著增大,且P_u值显著降低;当L/H≤2时,荷载与基坑的距离L对地基极限承载力P_u的影响很大,地基极限承载力P_u随L的减小而显著减小,当L/H>3时,L的影响逐渐减小,且P_u逐渐趋近于无基坑开挖时的值;P_u随地基荷载作用宽度B的增大而呈线性增大;支护桩的位移越小,P_u值越接近无基坑开挖时的地基极限承载力。 相似文献
756.
非饱和土土-水特征曲线(SWCC)表示了土中含水量与吸力之间的关系。针对非饱和土干-湿循环过程中的吸力变化特征,开展试验研究。采用体积压力板仪实现非饱和土的脱湿和吸湿过程。试验成果显示:(1)土-水特征曲线是不稳定的,它与土体含水率的变化路径有关;(2)在干湿循环过程中,相同的基质吸力具有不同的含水量。 相似文献
757.
758.
759.
760.
Zhang B Hong M Zhang B Zhang XL Zhao YS 《Environmental monitoring and assessment》2007,133(1-3):379-386
Endemic fluorosis was investigated and studied in the west region of the Songnen plain, Northeast China in 2001–2002. The
results showed that the fluorine distribution in aquatic environment was that the fluorine concentrations in the lake water
and unconfined ground water were higher than that in the river water and confined ground water. The lake water (Alkali lake)
is connected with unconfined ground water. In unconfined ground water, from the east and southeast areas to the west and the
northwest areas of the plain, fluorine concentration fluctuated with high and low alternatively. The fluorine in the water
comes from the weathering of rocks and minerals in the mountains and hills around the Songnen Plain. The main influence factors
of the fluorine distribution in aquatic environment are discussed. Unconfined ground water containing high fluorine is used
as drinking water. In this region, the fluorine concentration in drinking water is evidently correlated to the morbidity of
dental and skeletal fluorosis. High fluorine concentration in drinking water has endangered human health. 相似文献