Nanomaterial Behavior and Transformation in Aquatic Environments

Engineered nanomaterials entering aquatic systems undergo a complex interplay of physical, chemical and biological processes that determine their fate, transport and ecological impacts. In natural waters, nanoparticles may aggregate or disaggregate depending on ionic strength, pH and the presence of natural organic matter, which influences their colloidal stability and sedimentation rates. Surface ligands—from intentionally applied coatings to naturally derived organic molecules—mediate interactions with mineral surfaces and dissolved species, altering dissolution kinetics and transformation pathways. Metal and metal‐oxide nanoparticles can release ions through corrosion or photochemical reactions, and may generate reactive oxygen species that affect aquatic organisms. Concurrently, secondary processes such as adsorption onto particulates, precipitation of new mineral phases and biotic transformations can immobilise or remobilise nanomaterials. The dynamic balance of these mechanisms underpins the global significance of nanoparticle behaviour in freshwater and marine environments, informing risk assessments and guiding the design of safer nanomaterials.

Research from Nature Portfolio

Particulate organic matter has been shown to act as a widespread redox mediator in surface environments, reducing silver ions under solar irradiation to form silver nanoparticles. This natural pathway contributes an estimated 11–31 % of soil AgNPs, reshaping our understanding of AgNP sources and influencing biogeochemical cycling of silver and other contaminants. A novel quantitative method has been developed to measure nanoparticle surface hydrophobicity by comparing binding affinities to engineered collectors of varying wettability. This approach provides a direct metric of surface energy, linking hydrophobicity to nanoparticle interaction potential, colloidal behaviour and transport in aquatic systems.

Nanomaterial Behavior and Transformation in Aquatic Environments publication trend

The graph below shows the total number of articles in nanomaterial behavior and transformation in aquatic environments across all publications each year (not limited to Nature Index journals).

Technical terms

Agglomeration: The reversible clustering of nanoparticles driven by van der Waals attractions and electrostatic interactions.

Dissolution: The process by which solid nanoparticles release constituent ions into the aqueous phase.

Colloidal stability: The ability of dispersed nanoparticles to resist aggregation and remain suspended.

Surface ligands: Molecules or functional groups bound to nanoparticle surfaces that influence interaction with the environment.

Reactive oxygen species (ROS): Highly reactive molecules such as hydroxyl radicals and superoxide generated by nanoparticle surface reactions.

Hydrophobicity: A measure of a nanoparticle’s tendency to repel water, affecting aggregation and adsorption behaviours.

Natural organic matter (NOM): A heterogeneous mixture of organic compounds in natural waters that interacts with nanoparticles to modify their fate.

References

1. Transformation of zinc oxide nanoparticles in the presence of aluminum oxide with pre-sorbed phosphorus ligands. Environment International (2023).
2. Transformation of CuO Nanoparticles in the Aquatic Environment: Influence of pH, Electrolytes and Natural Organic Matter. Nanomaterials (2017).
3. Significant contribution of metastable particulate organic matter to natural formation of silver nanoparticles in soils. Nature Communications (2019).
4. Reactive Oxygen Species Formed by Metal and Metal Oxide Nanoparticles in Physiological Media—A Review of Reactions of Importance to Nanotoxicity and Proposal for Categorization. Nanomaterials (2022).
5. Direct quantification of nanoparticle surface hydrophobicity. Communications Chemistry (2018).