NanoFASE - nanofase-case-study-uptake-and-elimination-kinetics-of-ag-nps-in-freshwater-snails

During the household or industrial washing of nano-enabled products, silver nanoparticles (Ag-NPs) can be released to the municipal sewer system, ending up in waste water treatment plants (WWTPs) and transferred to aquatic environments through effluent discharge (Figure 1). Freshwater systems are important sinks for NPs, especially the sediment phase where benthic organisms can be exposed through water and sediment. In this work, we studied the kinetics in freshwater snails of pristine Ag-NPs of different sizes (3-8 nm, 50 nm and 60 nm) and a simulated aged form (Ag₂S-NP), produced by NanoFASE partners AMEPOX Enterprise and Applied Nanoparticles. The kinetic parameters derived from this study were included in the NanoFASE model.

Study aim

Determine uptake and elimination kinetics of different forms of Ag-NPs in the freshwater snail Physa acuta.

Image credit: S. Gonçalves

Experimental approach

Overview

üAg-NP 3-8, 50, 60 nm

üAg₂S-NP 20 nm

üAgNO₃

Clean medium

Uptake phase à contaminated aqueous medium at 10 µg Ag.L^-1 for 7 days
Transfer to clean medium at day 7
Elimination phase à clean medium for 7 days
Snails sampled throughout the experiment
Soft body and shell separated and digested
Total Ag concentrations determined in soft body, and shell

Environmental medium:

Freshwater
Sediment

NP type/size:

Ag-NPs 3-8 nm, 50 nm and 60 nm;
Ag₂S-NP 20 nm

Species:
Physa acuta
(freshwater snail)

Bio-assay:
Bioaccumulation assay

Results

Higher uptake rate constants (k1) for snail soft body exposed to Ag-NPs 60 nm, AgNO₃ and Ag₂S-NPs;
Lower uptake rate constants for snails exposed to Ag 3-8 nm and 50 nm;
Ag₂S-NPs are eliminated faster from the body than the other Ag forms tested;
No elimination determined for snails exposed to Ag 3-8 nm and AgNO₃;
Snail shell revealed some accumulation/adsorption of Ag, with higher values determined for the exposure to Ag 50 nm.

Modelling parameter outputs

Compartment

k1 - uptake rate constant (L.g^-1_{dw organism.day}^-1)
k2 elimination rate constant (day^-1)

Water/Sediment Biota

Read also

Visit the NanoFASE Library:
NanoFASE Report D9.2, Loureiro S. et al., Parameter sets on uptake and toxicokinetics of selected pristine NMs in aquatic and terrestrial organisms.

Silva PV, van Gestel CAM, Verweij RA, Loureiro S (2019) Toxicokinetics of pristine and aged silver nanoparticles in freshwater benthic organisms: the role of exposure route. SETAC Poster.