Publications

Authors: David Picón Borregales, Leticia Pastormerlo, Eduardo Reciulschi, Javier M. Montserrat

Publication date: December 2024

Abstract: Polyethylene macro, meso, and microplastics collected from horticultural soils in Moreno, Buenos Aires, Argentina, were studied to understand their physicochemical transformations after environmental exposure. These plastics contained mechanically stable compounds of Si (1.2–4.0 %), Al (0.91–1.5 %), and Fe (0.64–2.2 %), likely due to soil clay particles adhering to the plastic. The plastics' surfaces were oxidized, with high carbonyl (0.05–0.23) and hydroxyl (1.6–2.7) indices. Weathering led to thinner, rougher surfaces with increased contact angles due to the presence of clay and polar organic groups. Scanning electron microscopy (SEM) showed cracks and particles on the surfaces, while atomic force microscopy (AFM) revealed roughness increased from 0.44 nm in pristine polyethylene (p-PE) to 1.60 nm in weathered samples. 

Authors: Paulina Córdoba, Giselle Berenstein , Javier M. Montserrat 

Publication date: January 2025

Abstract: Trifluralin, Chlorpyrifos, and Procymidone migration performance from polyethylene (PE) and biodegradable (Mater-Bi: M-B) mulching films was examined. Desorption of pesticides from PE and M-B was studied using soil-plastic microcosms, considering temperature, soil humidity, and mulching film type as experimental variables. Trifluralin and Chlorpyrifos desorption was higher for PE than for M-B under all experimental conditions. In both cases, as the temperature increased from 25 °C to 40 °C, pesticide migration also increased, whereas as the soil humidity raised from 30% to 60%, pesticide desorption decreased. In the case of Procymidone, migration from PE and M-B at 25 °C was similar under both soil moisture conditions. Migration percentages were similar for both mulch films at 40 °C and 30% soil humidity. However, at higher soil moisture (60%), migration from M-B was greater than from PE. A linear relationship was observed between the percentage of migration and the vapor pressure of the pesticides. In all cases, migration increased with higher vapor pressure, indicating a possible migration mechanism in the vapor phase. Pesticide migration increased at high temperatures (40 °C). The effect of soil humidity in reducing pesticide migration was more significant at lower levels (30%).

In addition, the mesoplastic sorption of pesticides in soil columns was studied using PE and M-B films. While the recoveries for Trifluralin, Chlorpyrifos, and Procymidone in the PE films were 0.05% ± 0.01%, 0.13% ± 0.03%, and non-detectable, the recoveries for M-B were: 0.49% ± 0.07%, 0.31% ± 0.09%, and 0.17% ± 0.10%, respectively, indicating that M-B was a better adsorbent than PE in all cases. This behavior should be considered in combination with the lower migration percentages observed for this type of mulching film in the microcosm experiments. These results could indicate a potential carrier effect of pesticide on biomesoplastic in the environment.

Authors: Giselle Berenstein, Paulina Córdoba, Yamila B. Díaz, Nicolás González, María Belén Ponce, Javier M. Montserrat

Publication date: January 2024

Abstract: Soil contamination with plastics is a major worldwide concern. However, data on plastic pollution in horticultural soils from Latin America is scarce. Furthermore, there is limited information on the fragmentation process that plastics undergo in environmental conditions. In this study, we investigated the abundance of macro, meso, micro and nano plastics in a previously studied horticultural soil (2015) from Buenos Aires, that has not been used for any productive activity since. Although the mass of macroplastics was conserved, the number of plastic fragments per square meter increased significantly, indicating a possible natural fragmentation process. Black polyethylene (PE) mulch film was the most abundant plastic found. For this material, when considering the mass of plastic fragments per square meter, the relative abundance was, in decreasing order: macroplastics (65.1–79.1 %) > mesoplastics (15.6–24.8 %) > microplastics (5.3–12.4 %) > nanoplastics (0.1 %). However, when considering the number of plastic items per square meter, the order was: microplastics (2383–3815) > mesoplastics (1019–1076) > nanoplastics (509–550) > macroplastics (25–46). The size distribution of plastic debris was analyzed using the natural logarithm of abundance versus the square root of the mean decile area, with good linear correlations (0.7749 < R2 < 0.9785). These results provide evidence for an ongoing dynamic fragmentation process (Mott model). We hypothesize that the breakdown of plastic into smaller pieces could be explained by a random fragmentation process based on soil volume changes between natural hydration/dehydration states. These data suggest that soil under natural conditions could act as an ‘environmental plastic grinder’.