Silver Nanoparticles Impact As Emerging Soil Contaminants: A Review of Current Knowledge and Challenges

Purpose: The aim of this review is to synthesize and critically analyse current knowledge on the presence, transformations, and interactions of silver nanoparticles (AgNPs) in soil environments. It investigates how physicochemical processes, and biological interactions influence the fate, bioavailability, and ecological risk of AgNPs in soils, while also identifying regulatory and analytical gaps that limit reliable long-term environmental assessment. Materials and methods: This review was conducted through a systematic and critical analysis of peer-reviewed literature, regulatory documents, and technical reports published up to 2025. Major scientific databases were searched using combinations of keywords including silver nanoparticles , soil , transformation , bioavailability , toxicity , microbiome , and risk assessment . Studies focusing on terrestrial environments were prioritized, while biomedical and purely laboratory-based toxicological works were included only when relevant to environmental processes. Attention was given to research addressing physicochemical transformations of AgNPs, interactions with soil microbiota, and methodological challenges in detection and characterization. Regulatory and policy documents from international agencies and national authorities were reviewed to identify gaps in legislative frameworks. The collected materials were critically compared to highlight consistencies, discrepancies, and knowledge gaps, forming the basis for an integrated assessment of AgNPs in soil ecosystems. Results and Discussion: The reviewed literature confirms that soil acts as the principal sink for silver nanoparticles, where complex transformations such as dissolution, sulfidation, and aggregation govern their environmental fate. These processes strongly modulate AgNPs bioavailability, shaping both toxicity and persistence in soils. Evidence indicates that AgNPs interact closely with microbial communities, leading to shifts in diversity and functional potential, with possible consequences for nutrient cycling and plant health. Despite growing insights, substantial analytical challenges remain in detecting and characterizing AgNPs within heterogeneous soil matrices. Moreover, regulatory frameworks still lack provisions for long-term monitoring and life cycle–based assessments. Integrating chemical, biological, and regulatory perspectives is therefore essential for advancing accurate environmental risk assessment of AgNPs in terrestrial ecosystems. Conclusions: Silver nanoparticles represent a significant emerging pollutant in soils, where their transformations and interactions critically influence bioavailability and ecological risk. Current evidence highlights impact on microbial diversity and soil functioning, yet analytical limitations and regulatory gaps hinder robust long-term assessment. An integrated approach that combines physicochemical, biological, and policy perspectives is essential to advance environmental risk assessment and guide effective management of AgNPs in terrestrial ecosystems.