Nanoscale silver (n-Ag) including silver nanoparticles (Ag-NPs), silver chloride nanoparticles (AgCl-NPs), and silver sulfide nanoparticles (Ag 2 S-NPs) and their corresponding ionic counterpart, namely, dissolved Ag, may coexist in soils. X-ray absorption near edge spectroscopy (XANES) is used to elucidate the speciation of n-Ag in soils, whereas it possesses drawbacks like high costs, rare availability of the instrument, and providing semiquantitative data. We developed a new method for the identification and speciation of n-Ag in soils and sediments based on a sequential extraction technique coupled with inductively coupled plasma optical emission spectrometry. Extraction conditions were first evaluated, establishing the optimal extraction procedure; Ag-NPs, AgCl-NPs, and dissolved Ag in soil were simultaneously extracted by using an aqueous solution of 10 mM tetrasodium pyrophosphate, followed by selective isolation and quantification via AgCl-NPs dissolution (4.45 M aqueous ammonia), centrifugation (Ag-NPs), and detection. The Ag 2 S-NPs remaining in the soil were then extracted with Na 2 S solution at pH 7.0 through selective complexation. Optimal recoveries of Ag-NPs, AgCl-NPs, Ag 2 S-NPs, and dissolved Ag were 99.1 ± 2.4%, 112.0 ± 3.4%, 96.4 ± 4.0%, and 112.2 ± 4.1%, respectively. The method was validated to investigate the speciation of n-Ag in soils and sediments, exhibiting the distribution of Ag-NPs, AgCl-NPs, Ag 2 S-NPs, and dissolved Ag in each sample, wherein Ag 2 S-NPs, the major species of n-Ag, accounted for 35.42−68.87% of the total Ag. The results of n-Ag speciation in soil are comparable to those obtained through the linear combination fitting of XANES. This method thus is a powerful, yet convenient, substitute for XANES to understand the speciation of n-Ag in complex solid matrices.S ilver nanoparticles (Ag-NPs) have become an important component in personal care products and functional textiles due to their broad-spectrum antibacterial properties, resulting in potential release into the environment during production, usage, and disposal. 1−4 Once Ag-NPs are released into the environment, chemical transformations such as dissolution, chloridation, and sulfidation are inevitable, depending on the composition and nature of the respective environment. 5−9 As a result, nanoscale silver (n-Ag) including Ag-NPs, silver chloride nanoparticles (AgCl-NPs), and silver sulfide nanoparticles (Ag 2 S-NPs) and their corresponding ionic counterpart, namely, dissolved Ag, may coexist in the environment. In general, the bioavailability and potential hazards of n-Ag highly depend on its speciation, since dissolved Ag, Ag-NPs, and AgCl-NPs are considered as biologically active species, whereas Ag 2 S-NPs are inert for (micro)organisms. 10−13 Soils and sediments are ultimate sinks for n-Ag. 14,15 However, a large obstacle is the lack of proper methods for
