NanoFASE - element

Silver nanoparticles can enter the soil through the application of sewage sludge to agricultural land. The silver in the sewage sludge will most likely be in the transformed, sulphidised form. Plants growing on this agricultural land will thus be exposed to silver and have to potential to accumulate silver in their tissues. Varying soil properties can affect the bioavailability and bio-uptake in plants ; NanoFASE has therefore investigated the effect of a range of soils upon the bio-uptake of silver to plant tissues in the crop plant, Triticum aestivum (wheat).

Study aim
This study investigates the uptake of Ag from different Ag forms (Ag⁰Engineered NanoMaterials , Ag₂S ENM and AgNO₃) in wheat, Triticum aestivum, exposed in three different natural soils (Lufa 2.2, Woburn and North Wales).
Experimental approach	Overview
Three soils (Lufa 2.2, Woburn and North Wales) were spiked separately with three different forms of silver, each at a concentration of 10 mg Ag/kg. After 7 days, seeds were planted in the spiked soils. Plants were sampled at 1, 4, 6, 13 and 27 days post-emergence and the silver concentration was measured separately in the plant roots and shoots using graphite furnace atomic absorption spectroscopy (GF-AAS). Soil pore waters were extracted after 1, 6 and 27 days and total Ag was measured in the pore water and in ultra-filtered pore water samples.	Compartment involved: Soil NP type/size: Ag NP PVP coated - 20nm (AppNano) Ag₂S NP - 27 nm (AppNano) Species: Wheat (Triticum aestivum) Bioassay: Bioaccumulation assay

Results

The rate of uptake was highest in the Woburn soil compared to North Wales and Lufa 2.2.

The uptake of Ag was highest from the pristine 20 nm Ag NP PVP coated particle, while Ag₂S was either lower than or the same as the uptake from the AgNO₃ ionic reference.

Parameters

Uptake rate from soil - \(k_{1sc}\)
Elimination rate (soil) - \(k_{2sc}\)
Uptake rate from soil pore water - \(k_{1PW}\)
Elimination rate (soil pore water) -\( k_{2PW}\)
Growth rate – \(k_g\)
Bioaccumulation factor - \(BAF\)
Transfer function – \(TF\)
Pore water concentrations

Visit the NanoFASE Library to read summaries of these reports:

NanoFASE Report D7.2 Soil property – NM fate relationships

NanoFASE Report D9.2 Parameter sets on uptake and toxicokinetics of selected pristine NMs in aquatic and terrestrial organisms (summary of internal report)

Wang, P., et al. (2015). "Silver sulfide nanoparticles (Ag2S-NPs) are taken up by plants and are phytotoxic." Nanotoxicology 9(8): 1041-1049.

Dolette, C. L., et al. (2015). "Bioavailability of silver and silver sulfide nanoparticles to lettuce (Lactuca sativa): Effect of agricultural amendments on plant uptake." Journal of Hazardous Materials 300: 788-795.

Stegemeier, J. P., et al. (2015). "Speciation Matters: Bioavailability of Silver and Silver Sulfide Nanoparticles to Alfalfa (Medicago sativa)." Environ Sci Technol. 49(14): 8451-8460.