Atmosphere profiles and spatial distributions of rare earth element-containing nanoparticles released from multiple...

Rare Earth Elements (REEs) are toxic and pose environmental and exposure hazards. Limited research has analyzed REE mass concentrations during some industrial emissions currently. Nonetheless, the toxicity of REEs-containing nanoparticles (NPs) is predominantly governed by particle size and particle number concentrations (PNCs), surpassing the influence of mere mass concentration. Knowledge pertaining to the emissions of REE-containing NPs and their PNCs is lacking. In this study, REE-containing NP emissions from 132 industrial PM samples, spanning 13 categories of industrial sectors, were quantified. Ce and La were the most abundant elements across these 13 industrial sources. Among the 13 sources investigated, coal-fired power plants (CFPP) consistently exhibited the highest PNCs in most cases. CFPP had the highest particulate number concentrations of Ce-containing NPs, with a mean value of 1.9 × 10¹⁰ particles/g. In terms of atmospheric Ce- and La-containing NPs, CFPP, cement kiln co-processing of solid waste (CK), coking production, and blast furnace pig iron steelmaking were significant industrial emitters both in China and globally. Emissions from the 13 industrial sources significantly increased the atmospheric steady-state concentrations of both La- and Ce-containing NPs, with La rising by approximately 10⁵ particles/m³ and Ce by 10⁶ particles/m3, respectively. Consequently, the lifetime average daily dose (LADD) of La- and Ce-containing NPs for adults, via inhalation and dermal exposure, is calculated to be 2.0 × 10⁵ particles/(day·kg) and 8.1 × 10⁵ particles/(day·kg), respectively. These findings highlight the importance of assessing REE-containing NP emissions and advancing sustainable global industrial development.