Opportunities for examining the natural nanogeochemical environment using recent advances in nanoparticle analysis

The characterization of engineered nanoparticles (ENPs) has been a main pillar in the advancement of nanotechnology in recent decades. Because the properties of ENPs are closely linked to their size, shape, morphology, and surface coatings, development of nanoanalysis methods capable of assessing these parameters was necessary. Many advanced instruments and data analysis tools have now been established for analysis of ENPs in complex matrices, providing a comprehensive assessment of not only their intended virtues, but also the unintended consequences of their manufacture, use, and disposal. Current generation electron microscopy enables atom-scale imaging. Hyphenated (FFF-ICP-MS), and single particle (spICP-MS) techniques now possess the requisite sensitivity and elemental selectivity to quantify and characterize inorganic ENPs. These tools also provide a means to examine processes involving naturally-occurring nanoparticles (NNPs) to a degree not previously attainable. Though colloids and nanominerals have been investigated for decades, modern nanoanalysis offers a wealth of opportunities to improve our understanding of the natural nanogeochemical environment. Applying nanoanalysis on a single particle basis may lead to a more mechanistic understanding of particle formation and reactivity, global biogeochemical cycling, quantifying nanoparticle transport and impacts as they relate to hydrochemical and geochemical factors, and possibly differentiating ENPs from NNPs. Current approaches provide a view of natural nanomaterials while emerging technologies open the door to further studies of nanogeoscience.