A high sensitivity magnetic sector ICP-MS has been used in single particle mode with microsecond dwell times and particle detection limits of <10 nm.

With growing applications of TiO 2 nanoparticles (NPs) in outdoor surface coatings, notably in paints and stains, their release into the environment is inevitable. While NP release has potential ecotoxicological risk, reliable risk assessments are often complicated by the near absence of analytical data on release rates under natural weathering scenarios, and the lack of a chemical characterization of the NPs following their release. This work measured NPs released from painted and stained surfaces and characterized them by size and composition using magnetic sector single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) and SP-ICP-time-of-flight-MS (SP-ICP-TOF-MS). Two in situ experimental plans were examined in which natural precipitation interacted with nano-enhanced surfaces to varying degrees during the fall and winter. Weathering data showed that longer contact times of the precipitation (snow and rain) resulted in greater NP release. Although the stained surfaces had far fewer NPs per unit area, they lost a much higher fraction of their NP load (max 6% leached, as opposed to <10 −4% in paints), over similar exposure times. NP release was particularly enhanced for conditions of frequent rainfall and spring snow melt (i.e., slushy snow). SP-ICP-TOF-MS measurements on the Ti NPs indicated that they were often associated with a secondary metal in both the liquid paint (Al was detected in ∼20% of the Ti NPs; Zr in about ∼1% of the NP) and the liquid stain (Fe was detected in ∼7%, Si in ∼8% and Al in ∼3% of the Ti NPs). In contrast, for the vast majority of Ti NPs being leached out of the painted/stained surfaces, only Ti was detected. Metal interactions in the paint were explained by binding of the TiO 2 within a complex paint matrix; while in the stain, TiO 2 NPs were hypothesized to be found in heteroagglomerates, potentially with aluminosilicates (Fe, Si, and Al). In rain and snow, Ti was the only element detected in about half of the Ti NPs; in the other half, Ti often co-occurred with Fe, Si and Al. The results indicate that single element, likely anthropogenic, Ti NPs are already prevalent in the natural precipitation and that NP release from surface coatings will further increase their presence in the environment.

Nanoparticle (NP) emissions to the environment are increasing as a result of anthropogenic activities, prompting concerns for ecosystems and human health. In order to evaluate the risk of NPs, it is necessary to know their concentrations in various environmental compartments on regional and global scales; however, these data have remained largely elusive due to the analytical difficulties of measuring NPs in complex natural matrices. Here, we measure NP concentrations and sizes for Ti-, Ce-, and Ag-containing NPs in numerous global surface waters and precipitation samples, and we provide insights into their compositions and origins (natural or anthropogenic). The results link NP occurrences and distributions to particle type, origin, and sampling location. Based on measurements from 46 sites across 13 countries, total Ti-and Ce-NP concentrations (regardless of origin) were often found to be within 10 4 to 10 7 NP mL −1 , whereas Ag NPs exhibited sporadic occurrences with low concentrations generally up to 10 5 NP mL −1 . This generally corresponded to mass concentrations of <1 ng L −1 for Ag-NPs, <100 ng L −1 for Ce-NPs, and <10 μg L −1 for Ti-NPs, given that measured sizes were often below 15 nm for Ce-and Ag-NPs and above 30 nm for Ti-NPs. In view of current toxicological data, the observed NP levels do not yet appear to exceed toxicity thresholds for the environment or human health; however, NPs of likely anthropogenic origins appear to be already substantial in certain areas, such as urban centers. This work lays the foundation for broader experimental NP surveys, which will be critical for reliable NP risk assessments and the regulation of nano-enabled products.

Improved single particle ICP-MS characterisation of Ag nanoparticles in a lake ecosystem using microsecond dwell times.

No abstract