Analytical tools for measuring and characterizing nanomaterials in the environment
|關鍵字:||奈米微粒採樣分析;奈米微粒質量平衡;奈米物質環境安全衛生;nanoparticle sampling and analysis;mass closure of nanoparticles;EHS of nanomaterials|
|摘要:||國外的學者研究發現，附著金屬及有機物的奈米微粒會對人體健康造成傷害(Donaldson et al., 2002; Oberdörster et al., 2005; Peter et al., 1997)，因此對不同大氣環境下奈米微粒的濃度及其化學成分做定性定量相當重要，然而目前國際上尚沒有任何一個研究團隊能準確的採集並分析奈米微粒的所有物種。本研究選擇一般民眾、學生、駕駛乘客、遊客及作業勞工或工廠附近居民容易長時間暴露奈米微粒的地方，包括新竹學府路的道路旁、雪山隧道內、溪頭森林及四間潛在奈米微粒逸散的工廠周界及排放管道，探究人體可能暴露奈米微粒的情形。研究中我們使用國際上最先進的設備及技術，並透過採樣儀器操作的改善、採樣誤差的修正及嚴格的QA/QC，且經由不同儀器比對的驗證，結果證明我們能準確地採集奈米微粒，並可靠的分析出各種微粒的化學成份，包括：有機碳(OC)、元素碳(EC)、水溶性離子(Ions)及金屬元素(Element)。這些研究成果不僅對奈米微粒暴露及毒性相關的研究相當有幫助，同時也具有高度的國際水準及競爭力。
結果發現路旁PM0.1的日平均濃度為1.97±0.59 ug/m3，最主要成分為OM (organic mass, 路邊OM=1.6*OC；雪隧OM=1.4*OC；溪頭OM=2.1*OC)，佔38.7±3.3 %，次多成分為Ions，有23.2±9.3 %，元素及EC各為15.9±3.2 %及16.1±7.5 %。雪山隧道PM0.1的濃度在白天時高達32.2±6.5 ug/m3 (3小時採樣)；週末交通尖峰時濃度更可高達40 ug/m3以上；凌晨低車流量時也還有10 g/m3左右。OM及EC為雪隧PM0.1主要的成分，分別佔微粒質量31.4±5.1及27.8±5.4%。溪頭森林的量測發現，晴天的中午時段會有小於10 nm的微粒生成，主要是是光化作用所致，相對於路旁及雪隧，森林PM0.1的濃度相當低，平均濃度僅約0.65±0.31 ug/m3，OM及元素為主要成分，各有24.1±3.0及14.2±3.5%，約40% 沒被分析出來的成分推測大部分為水份。
Some studies have found associations between the exposure of nanoparticle and adverse health effects due to bounded trace elements, metals as well as organic carbon on nanoparticles (Donaldson et al., 2002; Oberdörster et al., 2005). Therefore, it is important to measure the concentration of nanoparticles accurately and then quantify its chemical compositions. However, there hasn’t been any research team who is able to sample and analyze all chemical species for nanoparticles. The sampling sites were chosen based on the exposure likelihood of the city residents, students, drivers, tourists as well as workers. Thus, a road side of Poai Street in Hsinchu, Syueshan highway tunnel in Taipei, Experimental Forest of NTU in Nan-Tou and the ambient air or exhaust ducts of four nanopowder or high-tech factories were selected. This study not only used the best instruments and techniques to sample and analyze nanoparticles at different atmospheric conditions but also corrected the sampling artifact through the modification of the sampling devices and adopted of a strigent QA/QC procedure. By the comparison of measured results between different instruments, this study proved that the samples of nanoparticle could be collected precisely and the chemical compositions could be determined reliably, including OC (organic carbon), EC (elemental carbon), water-soluble ions and elements. The present results are useful to the studies of nanoparticle exposure and nano-toxicology. The road side sampling and chemical analysis showed the day average concentration of PM0.1 was 1.97±0.59 ug/m3 and the most aboudent species was the OM (organic mass, roadside OM=1.6*OC, tunnel OM=1.4*OC, forest OM=2.1*=OC) which accounted for 38.7±3.3% PM0.1. The Ions were the second majority species of particles, accounting for 23.2±9.3% of the mass. The EC and Elements were 15.9±3.2% and 16.1±7.5% of the mass, respectively. The highway tunnel sampling and real-time measurements showed the concentration of nanoparticles at daytime (9am-9pm) was 32.2±6.5 ug/m3 (average of three hours) while it decreased to 10 ug/m3 during midnight (0am-6am) and increased to more than 40 g/m3 (average of three hours) during the rush hour on holidays. The OM and EC were the majority of PM0.1 mass in the tunnel, which were 31.4±5.1% and 27.8±5.4%, respectively. PM0.1 of the NTU Experimental Forest was as low as 0.65±0.3 ug/m3. Meanwhile from the real-time size distribution of nanoparticles, it was found photoreaction formed nanoparrticles below 10 nm during the sunny noon. The OM and Element were the major mass of PM0.1 in the forest, which were 24.1±3.0% and 14.2±3.5%, respectively. The unknown of 40% PM0.1 mass is suspected to be water. This study also reviewed the latest literatures to bridge the knowledge gaps on measurement and characterization methods of nanomaterials and wrote eight reports on different topics, including “developing the assessment methods of the toxicity of manufactured nanomaterials in water”, “developing the reference nanomaterials for the toxicity test” and “nanomaterials measurement in the environment”, etc. Two meetings were held to discuss these eight topics and the comments from the participating experts were collected. We made concrete suggestions based on the reviewed reports and the comments of the experts on both the technical and policy aspects of the nanotechnology knowledge gaps. It is hoped this report is useful to the agencies concerned with nanotechnology EHS.
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