Title: Effects of soil particles and convective transport on dispersion and aggregation of nanoplastics via small-angle neutron scattering (SANS) and ultra SANS (USANS)

Abstract

Terrestrial nanoplastics (NPs) pose a serious threat to agricultural food production systems due to the potential harm of soil-born micro- and macroorganisms that promote soil fertility and ability of NPs to adsorb onto and penetrate into vegetables and other crops. Very little is known about the dispersion, fate and transport of NPs in soils. This is because of the challenges of analyzing terrestrial NPs by conventional microscopic techniques due to the low concentrations of NPs and absence of optical transparency in these systems. Herein, we investigate the potential utility of small-angle neutron scattering (SANS) and Ultra SANS (USANS) to probe the agglomeration behavior of NPs prepared from polybutyrate adipate terephthalate, a prominent biodegradable plastic used in agricultural mulching, in the presence of vermiculite, an artificial soil. SANS with the contrast matching technique was used to study the aggregation of NPs co-dispersed with vermiculite in aqueous media. We determined the contrast match point for vermiculite was 66% D₂O / 33% H₂O. At this condition, the signal for vermiculite was ~50–100%-fold lower that obtained using neat H₂O or D₂O as solvent. According to SANS and USANS, smaller-sized NPs (50 nm) remained dispersed in water and did not undergo size reduction or self-agglomeration,more » nor formed agglomerates with vermiculite. Larger-sized NPs (300–1000 nm) formed self-agglomerates and agglomerates with vermiculite, demonstrating their significant adhesion with soil. However, employment of convective transport (simulated by ex situ stirring of the slurries prior to SANS and USANS analyses) reduced the self-agglomeration, demonstrating weak NP-NP interactions. Convective transport also led to size reduction of the larger-sized NPs. Therefore, this study demonstrates the potential utility of SANS and USANS with contrast matching technique for investigating behavior of terrestrial NPs in complex soil systems.« less

Authors:

Astner, Anton F.  ^[1];

• Search DOE PAGES for author "Astner, Anton F."
• Search DOE PAGES for ORCID "0000-0003-1162-7426"

Hayes, Douglas G.  ^[1];

• Search DOE PAGES for author "Hayes, Douglas G."
• Search DOE PAGES for ORCID "0000-0003-0303-1411"

Pingali, Sai Venkatesh  ^[2];

• Search DOE PAGES for author "Pingali, Sai Venkatesh"
• Search DOE PAGES for ORCID "0000-0001-7961-4176"

O’Neill, Hugh M.  ^[2];

• Search DOE PAGES for author "O’Neill, Hugh M."
• Search DOE PAGES for ORCID "0000-0003-2966-5527"

Littrell, Kenneth C.  ^[2];

• Search DOE PAGES for author "Littrell, Kenneth C."
• Search DOE PAGES for ORCID "0000-0003-2308-8618"

Evans, Barbara R.  ^[2];

• Search DOE PAGES for author "Evans, Barbara R."
• Search DOE PAGES for ORCID "0000-0002-2574-2567"

Urban, Volker S.  ^[2]

• Search DOE PAGES for author "Urban, Volker S."
• Search DOE PAGES for ORCID "0000-0002-7962-3408"

---

+ Show Author Affiliations

1. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Biosystems Engineering and Soil Science
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Publication Date:

Tue Jul 21 00:00:00 EDT 2020

Research Org.:

Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Biological and Environmental Research (BER)

OSTI Identifier:

1651368

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

PLoS ONE

Additional Journal Information:

Journal Volume: 15; Journal Issue: 7; Journal ID: ISSN 1932-6203

Publisher:

Public Library of Science

Country of Publication:

United States

Language:

English

Subject:

59 BASIC BIOLOGICAL SCIENCES