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

Abstract

Land-applied municipal biosolids, produced from municipal wastewater treatment sludge, contributes to microplastics contamination in agroecosystems. The impacts of biosolids on microplastic concentrations in agricultural soil have been previously investigated, however, the potential for microplastics transport from biosolid-amended croplands has not been previously quantified. In this study, manure and biosolids were applied to field plots, runoff was collected following natural precipitation events and the potential of bacterial biofilm to grow on different microplastic morphologies was investigated. Higher concentrations of microplastics were detected in runoff from plots with land-applied biosolid in comparison with manure-amended and control plots. Fibers and fragments were the most frequently detected plastic morphologies in runoff, correlated with their decreased surface roughness. The potential of biosolids to contribute to microplastic contamination to U.S. surface waters was quantified which is among the first to quantify the potential for nonpoint source microplastic contamination of surface waters adjacent to agricultural production areas.

Plastics and Micro/Nano-Plastics (MNPs) in the Environment: Occurrence, Impact, and Toxicity

“…Beni et al reported higher concentrations of MPs in the runoff from croplands utilizing municipality sludge compared to croplands utilizing cattle manure as sources of fertilizer. Fibers and fragments were the most detected; however, films, foam, and beads were also observed [92]. Ross et al estimated that separate urban runoff outlets released between 1.9 million to 9.6 billion MPs every rain event to receiving water bodies [93], confirming that water runoff is a major pathway for transporting MNPs from land to aquatic environments (Figure 2).…”

A method for the extraction of microplastics from solid biowastes including biosolids, compost, and soil for analysis by µ-FTIR

“…Spiked microplastics did not decant and instead adhered to the walls of the vessel, and settled particulate matter transferred into the filtering apparatus. An alternative method of separating the supernatant is centrifuging the digested solids with a high-density saturated salt solution to compact the solids into a pellet to aid in decanting the supernatant [ 3 , 12 , 16 , [18] , [19] , [20] ]. Centrifuging of samples may further fragment or compact microplastics into the solids pellet reducing recovery efficiency [ 4 ].…”

Shapes of Hyperspectral Imaged Microplastics

“…A suitable shape category should, furthermore, be unambiguous and precise in describing a particle’s geometry. Commonly used shapes such as fiber , fragment , flake , pellet , bead , and foam are illustrative but not always well defined. , Still, many studies apply shape classes without clear geometric definitions, for instance, what characteristics define a fragment or a foam ? , Even with a clear definition, some shapes are only suitable for visual identification but not hyperspectral imaged microplastics, for instance, film. While unambiguous and precise geometric shapes can readily be defined, e.g., sphere , rectangle , and oval , it can be difficult to assign them to real microplastics as these can be of any shape.…”

“… 20 , 21 Still, many studies apply shape classes without clear geometric definitions, for instance, what characteristics define a fragment or a foam ? 5 , 22 Even with a clear definition, some shapes are only suitable for visual identification but not hyperspectral imaged microplastics, for instance, film. ( 20 ) While unambiguous and precise geometric shapes can readily be defined, e.g., sphere , rectangle , and oval , it can be difficult to assign them to real microplastics as these can be of any shape.…”