臺灣東部三處休憩水域含鈦奈米微粒之時空分布探討

Abstract

近幾年，人為二氧化鈦奈米微粒在產品中的應用越來越廣泛，且可能會對環境與人體造成危害。然而人們除了可能透過飲用飲用水暴露於人為二氧化鈦奈米微粒之外，也可能藉由於休閒水域戲水而導致直接的暴露。因此，本研究針對東部三條休閒河川水域，包含南澳南溪、荖溪與利嘉溪的休閒水域及其下游的淨水場取水口中的含鈦奈米顆粒進行時間密集型採樣，並利用多元素單粒子感應耦合電漿質譜儀分析淡季與旺季採樣期間含鈦奈米顆粒的分布狀況，以及使用元素比方法推估人為二氧化鈦奈米微粒質量濃度的變化。 結果顯示在淡季採樣期間，含鈦顆粒質量濃度、數目濃度、最常見粒徑範圍以及人為二氧化鈦奈米微粒質量濃度分別為0.16 ng/mL至3.80 ng/mL, 14.52 × 103 part./mL至460.5 × 103 part./mL, 26 nm至60 nm以及ND至2.342 ng/mL。另外，在旺季採樣期間，含鈦顆粒質量濃度、數目濃度、最常見粒徑範圍以及人為二氧化鈦奈米微粒質量濃度分別為0.32 ng/mL至8.19 ng/mL, 16.53 × 103 part./mL至850.5 × 103 part./mL, 32 nm至58 nm以及ND至7.994 ng/mL。 與淡季採樣期間相比，可以發現在旺季採樣期間，當遊客人數增加時，含鈦奈米顆粒濃度以及推估的人為二氧化鈦奈米微粒質量濃度可能會增加，在南澳南溪有發現最高的人為奈米二氧化鈦質量濃度。且根據統計分析，雖然含鈦奈米顆粒的質量濃度和數量濃度與遊客數量之間的相關性不高，但大多數相關性呈現顯著(p < 0.05)。尤其是南澳南溪，發現其相關係數大於0.6，且呈顯著相關(p<0.05)。造成濃度增加的可能原因包含了遊客在休閒水域戲水時對沉積物的擾動導致含鈦奈米顆粒的再懸浮，或是透過遊客塗抹含人為二氧化鈦奈米微粒的防曬乳或是其穿著的防曬衣進入休閒水域，進而將人為二氧化鈦奈米微粒釋放至水中。 本研究提供了對含鈦奈米顆粒的質量濃度、數量濃度、最常見粒徑分佈以及人為二氧化鈦奈米微粒的潛在人為暴露進行了時間密集型調查。希望這些數據有助於未來了解人為奈米顆粒的暴露風險評估以及其在環境上的分佈。

Release of TiO2 engineered nanoparticles (ENPs) in the environment is getting attention in recent years due to the increasing incorporation of ENPs in the daily products, which in turn may threaten human health and can possibly impact natural systems. In addition to being exposed through drinking water, people may also be directly exposed to TiO2-ENPs by visiting in recreational waters. Therefore, this study was conducted through time-intensive sampling for three recreational water rivers in the eastern Taiwan, including the South Nan-Ao Creek, the Lao Creek, and the Li-Jia Creek. Multi-element single-particle inductively coupled plasma mass spectrometry was applied to investigate the distribution of titanium-containing NPs (Ti-containing NPs) and the estimated mass concentration of TiO2-ENPs with elemental ratio method. The results showed that, during the off season sampling period, the mass concentration, the number concentration, the most frequent size ranges of Ti-containing NPs and the estimated mass concentration of TiO2-ENPs were from 0.16 ng/mL to 3.80 ng/mL, from 14.52 × 103 part./mL to 460.5 × 103 part./mL, from 26 nm to 60 nm and from ND to 2.342 ng/mL, respectively. On the other hand, during the peak season sampling period, these corresponding parameters were from 0.32 ng/mL to 8.19 ng/mL, from 16.53 × 103 part./mL to 850.5 × 103 part./mL, from 32 nm to 58 nm and from ND to 7.994 ng/mL, respectively. Compared with the off season sampling period, the peak season sampling period could be found that, as the number of visitors at recreational waters increased, the concentrations of Ti-containing NPs and estimated TiO2-ENPs might increase as well. The highest mass concentration of TiO2-ENPs was found in the South Nan-Ao Creek. Although the correlation coefficients between both the mass and number concentrations of Ti-containing NPs and the number of visitors were moderate, most of these correlations were statistically significant, with the highest correlation coefficients greater than 0.6 found in the South Nan-Ao Creek. The possible explanations for the increased concentrations include the re-suspension of Ti-containing NPs caused by the disturbance of sediments resulting from visitors’ playing in recreational waters, and the release of TiO2-ENPs into the recreational waters from the TiO2-ENPs containing sunscreen or clothing used by the on-site visitors at the recreational waters. This study provided a temporal information on the mass concentration, number concentration, and particle size distribution of Ti-containing NPs and the potential anthropogenic exposure to TiO2-ENPs in recreational waters. It is helpful in characterizing the environmental distribution of TiO2-ENPs and the future risk assessment for the potential exposure to TiO2-ENPs.