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Due largely to their ability to absorb UV light, cerium oxide (CeO2) nanoparticles (NP) are now widely used in numerous surface coatings. The release of CeO2NP from the surface coatings and their subsequent fate in the environment is difficult to evaluate, and to-date, has either been modelled, estimated using elemental mass balances or measured under controlled laboratory conditions. Single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) is emerging as one of the best techniques for detecting very small NP at very low concentrations in complex media such as natural waters, soils or biota. In this study, we first examined the role of different physicochemical properties (e.g., pH, ionic strength, and concentration of natural organic matter) on CeO2NP that were found in a paint and a stain. Their stability was then evaluated in rainwater over 30 days. Depending on the properties of the media, Ce NP concentrations in the paint decreased by 65–90%, whereas those in the stain decreased by 15–35% after 30 days. The loss was attributed to either dissolution or agglomeration/sedimentation. Finally, we quantified and characterized the release of both dissolved and particulate Ce from the two surface coatings under natural weathering conditions. In that case, Ce released from painted and stained panels was mainly shown to be in its dissolved metal forms. After 23 weeks of exposure, up to 15% of the Ce applied as paint and up to 35% of the Ce applied as stain were released into the precipitation. Nonetheless, no Ce NP beyond background levels were detected – all release appeared to be in the form of dissolved Ce.

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 104to 107NP mL–1, whereas Ag NPs exhibited sporadic occurrences with low concentrations generally up to 105NP mL–1. This generally corresponded to mass concentrations of <1 ng L–1for Ag-NPs, <100 ng L–1for Ce-NPs, and <10 μg L–1for 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.

Nanoplastics (NPs; <0.1 μm) are speculated to be a bigger ecological threat due to their predicted wider distribution, higher concentrations, and bioavailability. Primary NPs are manufactured to be that size, while secondary NPs originate from fragmentation of bigger debris. To date, the long-term impact of NPs in freshwater systems, particularly secondary NPs, is not well-understood. Thus, we employed a freshwater invertebrate, Daphnia magna, to investigate the chronic effects of model primary NPs, fluorescent polystyrene nanospheres (PS-NPs; 20 nm), and water leachate of weathered single-use plastics that contained micro- and nanosized particles. In experiment 1, parent Daphnia(F0) were exposed to 1 and 50 mg/L PS-NPs until the production of the neonates (F1) followed by a two-generation recovery. PS-NPs were mainly detected in the intestine and brood chamber in F0 and transferred to F1 and F2. PS-NPs significantly decreased the appendage curling and heartbeat rate in F0 and reduced reproduction in F2. In experiment 2, the plastic leachate also reduced the appendage curling rate but increased growth and reproduction. The results suggest that the acute toxicity of primary and secondary plastic particles is low even at high concentrations, but their chronic and sublethal effects should not be overlooked.

Paints and coatings represent one of the major applications of TiO2nanoparticles (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 TiO2NP 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 TiO2NPs. 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 × 1011NP per m2were released, corresponding to <0.001% of the TiO2NP 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.

As the production and use of engineered nanomaterials increase, there is an urgent need to develop analytical techniques that are sufficiently sensitive to be able to measure the very small nanoparticles (NP) at very low concentrations. Although single particle ICP-MS (SP-ICP-MS) is emerging as one of the best techniques for detecting NP, it is limited by relatively high size detection limits for several NP, including many of the oxides. The use of a high sensitivity sector field ICP-MS (ICP-SF-MS), microsecond dwell times, and dry aerosol sample introduction systems were examined with the goal of lowering the size detection limits of the technique. For samples injected as a wet aerosol, size detection limits as low as 4.9 nm for Ag NP and 19.2 nm for TiO2NP were determined. By using a dry aerosol, a significant gain in ion extraction from the plasma was obtained, which resulted in a noticeable decrease of the size detection limits to 3.5 nm for the Ag NP and 12.1 nm for the TiO2NP. These substantial improvements were applied to the detection of TiO2NP in sunscreen lotions, rainwaters, and swimming pool waters. Concentrations of Ti-containing NP between 27 and 193 μL–1were found in rain samples. Similar NP concentrations were detected in public swimming pools, although much higher particle number concentrations (6046 ± 290 μL–1) were measured in a paddling pool, which was attributed to a high concentration of sunscreen lotions in a small recirculated water volume. High losses of TiO2NP through adsorption or agglomeration resulted in recoveries ranging from 14–34%.

Wastewater effluents represent one of the main routes through which silver nanoparticles (Ag NPs) can reach natural aquatic environments, where they may interact with a range of organisms. However, in wastewaters, Ag NPs may undergo different chemical and physical transformations, which may alter NP toxicity towards aquatic organisms. The main objectives of this study are to characterize the dissolution and speciation of a Ag NP in a wastewater effluent and to assess its interactions with a model organism, Chlamydomonas reinhardtii(green alga), in the same medium. Experiments were conducted to distinguish the effect(s) of the wastewater matrix on the dissolution of Ag NPs and to determine whether the transformed NPs or the dissolved Ag species would be more bioavailable to C. reinhardtii. It was shown that in the wastewater effluent, Ag bioavailability was significantly reduced with respect to experiments using similar Ag concentrations in simple media. The substantial reduction in Ag bioavailability in wastewaters could be explained by the presence of high concentrations of organic/inorganic ligands, which complexed the Ag and the presence of substantial competing ions. Nonetheless, Ag NPs did appear to be bioavailable to C. reinhardtiiat higher concentrations, as observed from bioaccumulation experiments comparing dissolved Ag and Ag NPs. Since the biouptake of Ag NPs could not be explained by concentrations of free Ag alone, it was hypothesized that complexed Ag species and/or small NPs may have contributed to biouptake. The results suggested that the chemistry of wastewaters had a significant effect on the bioavailability of Ag NPs, by modifying their physicochemical transformations.