Higher concentrations of microplastics in runoff from biosolid-amended croplands than manure-amended croplands

Authors: BENI, NASRIN - University Of Nebraska; KARIMIFARD, SHAHAB - University Of Nebraska; Gilley, John; MESSER, TIFFANY - University Of Nebraska; SCHMIDT, AMY - University Of Nebraska; BARTELT-HUNT, SHANNON - University Of Nebraska

Submitted to: Nature Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/9/2023
Publication Date: 2/20/2023
Citation: Beni, N.N., Karimifard, S., Gilley, J.E., Messer, T., Schmidt, A., Bartelt-Hunt, S. 2023. Higher concentrations of microplastics in runoff from biosolid-amended croplands than manure-amended croplands. Nature Communications. https://doi.org/10.1038/s43247-023-00691-y.
DOI: https://doi.org/10.1038/s43247-023-00691-y

Interpretive Summary: Municipal biosolids, which are often land applied as a fertilizer, contain microplastics. Microplastics, which are defined as polymer particles smaller than 5 mm, may be transported from land application sites through storm water runoff. This study was conducted to determine the effect of land application of biosolids on the concentration of microplastics in agricultural runoff, and to identify the potential for microplastic transport from corn and soybean production areas within the United States. Six experimental plots were established at a research farm near Lincoln, NE. Biosolids from a wastewater treatment plant were applied on two of the plots, manure from a cattle production facility was added to two other plots, while two additional plots were maintained as controls. Sorghum was planted on each of the plots. Runoff samples were collected from each of the five significant precipitation events occurring during the summer of 2020. The microplastic concentrations in runoff ranged from 8 - 20 particles/L (manure plots), 10 - 14 particles/L (control plots), and 16 - 31 particles/L (biosolid plots). It is estimated that a total of 64 billion microplastic particles could potentially be transported by runoff from biosolids applied to corn and soybean fields in the United States each year.

Technical Abstract: Municipal biosolids are often land applied as a fertilizer and soil conditioner. Biosolids have been shown to contain microplastics which are defined as polymer particles smaller than 5 mm. Microplastics may be transported from land application sites through stormwater runoff. This study was conducted to determine the effect of land application of biosolids on the concentration of microplastics in agricultural runoff, and to identify the potential for microplastic transport from corn and soybean production areas within the United States. Six plots with dimensions of 3.6 m × 10 m were constructed at the University of Nebraska’s Rogers Memorial Farm located 19 km east of Lincoln, NE. Biosolids from a wastewater treatment plant were applied on two of the plots, manure from an operating cattle production facility in Nebraska was applied to two other plots, while two additional plots were maintained as controls and did not receive biosolids or manure. Sorghum was planted on each of the plots. Runoff samples were collected from each of the five significant precipitation events occurring during the summer of 2020. The microplastic concentrations in runoff ranged from 10 - 14 particles/L (control plots), 16 - 31 particles/L (biosolid plots) and 8 - 20 particles/L (manure plots). In general, microplastics found in runoff from the biosolid amended plots were significantly larger than those measured from the control plots. In comparison, the concentration of microplastics in runoff from the manure amended plots were not statistically different from the control plots. Microplastic particle distribution detected in runoff samples from all plots was on average 33% fibers, 63% fragments, 3% films, and 2% foam. It is estimated that a total of 64 billion microplastic particles could potentially be transported by runoff from biosolids applied to corn and soybean fields in the United States each year.