High-Resolution Characterization of Coal Combustion-Derived Metal-Containing Nanoparticles and Their Health-Related Implications
Xu et. al.
Environmental Science Technology Letters
DOI: 10.1021/acs.estlett.4c00292
This recent publication from researchers from East China Normal University showcases the use of our icpTOF R using single-particle ICP-TOFMS for multi-element composition in individual coal combustion-derived metal-containing nanoparticle (MCNPs). This study is a great first step in better understanding the health implication of these types of nanoparticles (NPs).
Recent studies have revealed the widespread presence of MCNPs in human bodily fluids and tissues, with their spherical morphology and associated transition metals resembling those from combustion processes. Coal-fired power plants (CFPPs) are a significant source of atmospheric MCNPs and toxic metals, particularly titanium and iron nanoparticles found in fly ashes. Despite only a small fraction of fly ash escaping through stacks, these emissions contribute substantially to the overall number of iron-containing nanoparticles. Additionally, during coal combustion, metals like zinc, arsenic, and lead can vaporize and condense on fly ash particles, creating potentially harmful MCNPs that coexist with these toxic metals.
Current methods for characterizing coal combustion-derived MCNPs often focus on a few metals using single-particle inductively coupled plasma mass spectrometry (sp-ICP-MS). However, coal combustion MCNPs are associated with various toxic trace metals. Single-particle ICP time-of-flight MS (sp-ICP-TOFMS) can simultaneously measure multiple elements in individual particles, offering detailed composition data. Recent applications of sp-ICP-TOFMS have identified unique elemental compositions in environmental samples and enabled source apportionment of atmospheric PM2.5. This study employed the icpTOF R to provide high-resolution characterization of MCNPs in coal combustion byproducts from a Chinese coal-fired power plant, focusing on identifying predominant MCNPs, illustrating toxic metal occurrence on particles, and evaluating their toxic potency.
A large number of NPs containing titanium, iron, zinc, and lead were identified in coal combustion byproducts (CCPs), with the highest concentrations found in the fly ash escaping through the stack (EFA). Most of these MCNPs were multi-metal, with zinc and lead present in low mass fractions, indicating their adsorption onto MCNPs. Aluminum, silicon, and iron were the dominant components. The concentration of volatile toxic metals increased through the dust removal stages, peaking in the EFA. Compared to MCNPs from the initial dust removal stage, those in the EFA showed a 78 % increase in oxidative stress and a 32 % increase in cytotoxicity, with cytotoxicity being about 14 times higher than that of PM2.5 from CFPPs. Up to 50% of iron-containing NPs were lead-rich, with these and iron associated with Al-rich NPs being significant in regulating intracellular ROS generation, posing oxidative-stress-related health risks. Zinc and lead were present in trace amounts, mostly associated with Al- and Si-rich NPs in coal fly ashes, and were linked to severe pulmonary toxicity, particularly from fly ash escaping through the stack.
Using sp-ICP-TOFMS, this study achieved high-resolution characterization of the multi-element composition in individual coal combustion-derived MCNPs. The findings highlight the distinct toxicity from Fe-containing NPs and toxic metals in Al- and Si-rich NPs, emphasizing the need for further toxicological studies on coal combustion-derived MCNPs. Given the variability in coal types, combustion conditions, and dust removal systems across power plants, more comprehensive studies like these using multi-element composition tools such as the icpTOF R will be needed to better understand the health risks of these nanoparticles.
