Title of Oral/Poster Presentation

Transformations of copper oxide nanoparticles in a rooted soil environment

Class

Article

Graduation Year

2017

College

College of Engineering

Department

Civil and Environmental Engineering Department

Faculty Mentor

Joan McLean

Presentation Type

Oral Presentation

Abstract

CuO nanoparticles (NPs), used as antimicrobials in coatings, paints, and potentially as a foliar antifungal, will inevitably result in soil contamination, but little is known about the fate and transformations of CuO NPs in soils. The objective of our research is to evaluate the transformations of CuO NPs (surface chemistry, dissolution, and bioavailability) in the soil environment - a complex mixture of minerals, organic matter, bacteria, and roots.

We conducted experiments utilizing soil pore waters (SPWs, extracted from soils which varied in organic matter additions) and sand contaminated with CuO NPs (100 mg Cu/kg sand) as the growth matrix for wheat seedlings. Wheat provided the rooted environment and also acted as a biosensor against the bioavailability of the NPs. Treatments included several SPWs, and the presence/absence of a soil bacterium, Pseudomonas chlororaphis O6 (PcO6). After 10 days of wheat growth in the sand medium, we measured the wheat response (root/shoot length and metal content), the solution phase chemistry, and the system copper mass balance.

The majority of the CuO NPs (85-95%) remained with the sand, while a small portion of the NPs was mobile (suspended in the solution phase or dissolved) and a very small portion was associated with the plant. The NPs became coated with dissolved organic matter and solubilized via complexation. Their dissolution was further enhanced by root exudates but not when PcO6 was present because of metabolism of the exudates. The SPWs partially lowered the bioavailability of the CuO NPs to the wheat. From these results, we expect CuO NPs to largely remain with the solid phase in soil, partially solubilizing depending on the dissolved organic matter concentration; we also expect that bioavailability of CuO NPs to plants and microbes in whole soils may be less than bioavailability seen in toxicological studies.

Location

Room 154

Start Date

4-13-2017 3:00 PM

End Date

4-13-2017 4:15 PM

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Apr 13th, 3:00 PM Apr 13th, 4:15 PM

Transformations of copper oxide nanoparticles in a rooted soil environment

Room 154

CuO nanoparticles (NPs), used as antimicrobials in coatings, paints, and potentially as a foliar antifungal, will inevitably result in soil contamination, but little is known about the fate and transformations of CuO NPs in soils. The objective of our research is to evaluate the transformations of CuO NPs (surface chemistry, dissolution, and bioavailability) in the soil environment - a complex mixture of minerals, organic matter, bacteria, and roots.

We conducted experiments utilizing soil pore waters (SPWs, extracted from soils which varied in organic matter additions) and sand contaminated with CuO NPs (100 mg Cu/kg sand) as the growth matrix for wheat seedlings. Wheat provided the rooted environment and also acted as a biosensor against the bioavailability of the NPs. Treatments included several SPWs, and the presence/absence of a soil bacterium, Pseudomonas chlororaphis O6 (PcO6). After 10 days of wheat growth in the sand medium, we measured the wheat response (root/shoot length and metal content), the solution phase chemistry, and the system copper mass balance.

The majority of the CuO NPs (85-95%) remained with the sand, while a small portion of the NPs was mobile (suspended in the solution phase or dissolved) and a very small portion was associated with the plant. The NPs became coated with dissolved organic matter and solubilized via complexation. Their dissolution was further enhanced by root exudates but not when PcO6 was present because of metabolism of the exudates. The SPWs partially lowered the bioavailability of the CuO NPs to the wheat. From these results, we expect CuO NPs to largely remain with the solid phase in soil, partially solubilizing depending on the dissolved organic matter concentration; we also expect that bioavailability of CuO NPs to plants and microbes in whole soils may be less than bioavailability seen in toxicological studies.