TY - JOUR

T1 - LDPE and biodegradable PLA-PBAT plastics differentially affect plant-soil nitrogen partitioning and dynamics in a Hordeum vulgare mesocosm

AU - Reay, Michaela K

AU - Greenfield, Lucy M

AU - Graf, Martine

AU - Lloyd, Charlotte E M

AU - Evershed, Richard P

AU - Chadwick, Dave R

AU - Jones, Davey L

N1 - Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.

PY - 2023/4/5

Y1 - 2023/4/5

N2 - Micro and macroplastics are emerging contaminants in agricultural settings, yet their impact on nitrogen (N) cycling and partitioning in plant-soil-microbial systems is poorly understood. In this mesocosm-scale study, spring barley (Hordeum vulgare L.) was exposed to macro or microplastic produced from low density polyethylene (LDPE) or biodegradable plastic at concentrations equivalent to 1, 10 and 20 years of plastic mulch film use. Partitioning of 15N-labelled fertiliser into plant biomass, soil and leachate yielded a partial mass balance. Soil N partitioning was probed via compound-specific 15N-stable isotope analyses of soil microbial protein. Concentration-dependent decreases in plant 15N uptake occurred with increased leached nitrogen for LDPE microplastic. Assimilation into soil microbial protein was higher for biodegradable plastics, which we associate with early-stage biodegradable plastic degradation. Partitioning of 15N into inorganic soil N pools was affected by LDPE size, with lower assimilation into the microbial protein pool. While microplastics and macroplastics altered soil N cycling, the limited impacts on plant health indicated the threshold for negative effects was not reached at agriculturally relevant concentrations. This study highlights the difference between conventional and biodegradable plastics, and emphasises that the interplay of micro and macroplastics on soil N cycling must be considered in future studies.

AB - Micro and macroplastics are emerging contaminants in agricultural settings, yet their impact on nitrogen (N) cycling and partitioning in plant-soil-microbial systems is poorly understood. In this mesocosm-scale study, spring barley (Hordeum vulgare L.) was exposed to macro or microplastic produced from low density polyethylene (LDPE) or biodegradable plastic at concentrations equivalent to 1, 10 and 20 years of plastic mulch film use. Partitioning of 15N-labelled fertiliser into plant biomass, soil and leachate yielded a partial mass balance. Soil N partitioning was probed via compound-specific 15N-stable isotope analyses of soil microbial protein. Concentration-dependent decreases in plant 15N uptake occurred with increased leached nitrogen for LDPE microplastic. Assimilation into soil microbial protein was higher for biodegradable plastics, which we associate with early-stage biodegradable plastic degradation. Partitioning of 15N into inorganic soil N pools was affected by LDPE size, with lower assimilation into the microbial protein pool. While microplastics and macroplastics altered soil N cycling, the limited impacts on plant health indicated the threshold for negative effects was not reached at agriculturally relevant concentrations. This study highlights the difference between conventional and biodegradable plastics, and emphasises that the interplay of micro and macroplastics on soil N cycling must be considered in future studies.

KW - (15)N stable isotope probing

KW - Amino acids

KW - Biodegradable Plastics

KW - Hordeum

KW - Macroplastic

KW - Microplastic

KW - Microplastics

KW - Nitrogen

KW - Plants

KW - Plastics

KW - Polyesters

KW - Polyethylene

KW - Risk threshold

KW - Soil

KW - Soil Pollutants

U2 - 10.1016/j.jhazmat.2023.130825

DO - 10.1016/j.jhazmat.2023.130825

M3 - Article

C2 - 36708602

VL - 447

JO - Journal of Hazardous Materials

JF - Journal of Hazardous Materials

SN - 0304-3894

M1 - 130825

ER -