Paints and coatings represent one of the major applications of TiO₂ nanoparticles (NPs). While it has been previously shown that NPs are released from painted surfaces, there is still a lack of experimental data on their release rates under natural conditions and on the size distributions of the NPs following release. This study quantifies TiO₂ NP release from painted surfaces under natural weathering conditions and identifies the main seasonal factors that contribute to increased NP release. First, an analytical methodology using a highly sensitive single particle inductively coupled plasma mass spectrometer (SP-ICP-MS) was developed that improved the size detection limit (SDL) of the technique down to <20 nm for TiO₂ NPs. Precipitation (rain, snow) was collected after it came into contact with painted panels that were exposed to natural weathering. NPs that were released from the paint, as well as those pre-existing in the precipitation were thoroughly characterized with respect to their size distributions, particle number concentrations and total metal content. During the 10 week winter exposure, 3 × 10¹¹ NP per m² were released, corresponding to <0.001% of the TiO₂ NP load on the panels, with most of the NPs found in the 20–60 nm range. Significantly fewer NPs were released during the summer than the winter, in spite of the fact that there was more precipitation in the summer. Controlled lab weathering experiments revealed that NP release was significantly enhanced for wet surfaces, particularly, when the samples underwent freeze–thaw cycles. The results also indicated that NP release and loss (i.e. through agglomeration, sedimentation or sorption, etc.) are dynamic processes that are a function of the physical and chemical properties of the external medium. Although NP release is a primary determinant in environmental risk, subsequent NP behavior leading to losses or re-suspension can be equally critical.

中文翻译：

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在寒冷气候下从涂漆表面释放TiO2纳米颗粒：使用高灵敏度单颗粒ICP-MS进行表征

油漆和涂料是TiO ₂纳米颗粒（NPs）的主要应用之一。尽管先前已经证明了NP从涂漆的表面上释放，但是仍然缺乏关于在自然条件下它们的释放速率以及释放后NP的尺寸分布的实验数据。这项研究量化了自然风化条件下从涂漆表面释放的TiO ₂ NP的数量，并确定了导致NP释放增加的主要季节性因素。首先，开发了一种使用高灵敏度单粒子电感耦合等离子体质谱仪（SP-ICP-MS）的分析方法，该方法将TiO ₂的技术的尺寸检测极限（SDL）降低至<20 nmNP。与暴露于自然风化的涂漆板接触后，会收集到沉淀物（雨，雪）。从涂料中释放的NPs，以及沉淀中预先存在的NPs的大小分布，颗粒数浓度和总金属含量都得到了彻底的表征。在冬季暴露的10周期间，每m ²释放3×10 ¹¹ NP ，相当于TiO _2的<0.001％面板上的NP负载，大多数NP在20–60 nm范围内。尽管夏季有更多的降水，但夏季释放的NP却比冬季少得多。受控的实验室风化实验表明，湿表面的NP释放显着增强，尤其是当样品进行冻融循环时。结果还表明，NP的释放和损失（即通过聚集，沉淀或吸附等）是动态过程，是外部介质的物理和化学性质的函数。尽管NP释放是环境风险的主要决定因素，但随后导致损失或重新悬浮的NP行为也同样重要。