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
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.