校園新建築自來水中鉛溶出之調查與鉛奈米顆粒流體行為之研究

Survey of Lead in Tap Water in New Campus Buildings and Hydraulic Behaviors of Lead Nanoparticles

呂宜芳(YI-FANG LU)

指導教授 ： 林逸彬

國立臺灣大學/工學院/環境工程學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202103046

摘要

自來水鉛污染是一長期被忽視的問題，其中從含鉛管材釋出之顆粒鉛對於自來水偶發性高濃度的鉛污染有很大的影響。然而，目前針對顆粒鉛，尤其是奈米等級鉛顆粒的釋出與傳輸尚未有詳細的研究。現今，鉛仍被廣泛做為黃銅管材的添加材料，因此，即使是新建築中的自來水也可能有鉛污染的問題。本研究針對國立臺灣大學內四棟新建築(屋齡<5年)中的13個水龍頭進行為期一年的水質監測。另外，針對其中一採樣點進行不同流況下(1.1, 3.3, 7.0, 13.3 L/min)鉛奈米顆粒的釋出之偵測，並搭配計算流體力學(CFD)模擬鉛奈米顆粒在水龍頭中之流體行為。新建築採樣監測中，以第一時間採樣(first draw sampling)與日間隨機採樣(random daytime sampling)總共採集了309個自來水樣本，搭配0.22 μm孔徑濾膜過濾，使用單顆粒式感應耦合電漿質譜儀(spICP-MS)檢測溶解鉛、總鉛及鉛奈米顆粒和其他金屬包含銅、鋅、鐵，以探討鉛與銅、鋅、鐵之間的相關性。實驗結果顯示，有3.2%的樣品總鉛濃度超過台灣飲用水含鉛量規範(10 μg/L)。在第四棟建築當中，溶解/總鉛濃度與溶解/總銅、鋅和鐵都呈現正相關。另外，第二棟建築中鉛奈米顆粒與銅奈米顆粒的粒子質量濃度上有最強之正相關性。第一時間採樣所得之鉛、銅、鋅奈米顆粒相較日間隨機採樣而言有較大的平均粒徑，推測原因為第一時間採樣之樣品於管線中之滯留時間較長，有較多較大粒徑鉛顆粒的累積。另外，於較高的流速下，採集到的鉛奈米顆粒有較高的粒子重量濃度與平均粒徑。CFD模擬結果顯示於紊流下(13.3 L/min)，更多的鉛奈米顆粒被沖刷並流出水龍頭。

關鍵字

鉛 ； 自來水 ； 奈米顆粒 ； 單顆粒式感應耦合電漿質譜儀 ； 計算流體力學

並列摘要

Lead contamination in tap water has been an overlooked issue. Specifically, the release of particulate lead from lead-containing plumbing materials contributes significantly to the sporadically high lead levels in drinking water. In-depth understanding of the release of particulate Pb, especially the transport of Pb nanoparticles, in tap water is still lacking. Currently, lead is still used as an additive in brass plumbing materials, suggesting that even in new buildings, lead contamination in drinking water can still be a problem. In this study, 13 faucets in four new buildings (<5 years) on the National Taiwan University campus were sampled for one year to monitor lead levels in drinking water. One particular faucet was selected to further investigate the release of Pb nanoparticles under different flow rates (1.1, 3.3, 7.0, 13.3 L/min). The computational fluid dynamics (CFD) was employed to simulate the hydraulic behaviors of Pb nanoparticles in the faucet. First draw sampling and random daytime sampling protocols were implemented to collect tap water samples. Coupled with filtration using 0.22 μm pore size membrane, single particle inductively coupled plasma mass spectrometry (spICP-MS) was used to measure soluble lead (<0.22 μm), total lead, and Pb nanoparticles as well as copper, zinc and iron in these samples to investigate their potential correlations. A total of 309 samples were collected and analyzed. It was found that 3.2% of the samples had total lead concentrations exceeding 10 μg/L. In Building 4, for soluble and total concentrations, lead was correlated with copper, zinc and iron, respectively. Specifically, in Building 2, Pb nanoparticles were strongly correlated with Cu nanoparticles in particle mass concentration. The first draw samples revealed a larger mean size than random daytime samples for Pb, Cu and Zn nanoparticles. The reason could be attributed to the overnight accumulation of corrosion products, which exaggerated particle size. Furthermore, it was found that a higher flow rate increased the particle mass concentration and the mean size of Pb nanoparticles. The results of CFD simulation showed that Pb nanoparticles scoured more to the outlet under turbulent flow (13.3 L/min).

並列關鍵字

Lead ； tap water ； nanoparticle ； single particle ICP-MS ； computational fluid dynamics

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