RESUMEN
It is crucial to elucidate the release rate of microplastics (MPs) and phthalic acid esters (PAEs) in agricultural soil and their effects on crop productivity regarding film types and thicknesses. To address this issue, two-year landfill test was performed using 0.016 mm-thick polyethylene (PEt1) & biodegradable (BIOt1), and 0.01 mm-thin polyethylene (PEt2) & biodegradable (BIOt2) residual films as materials with no landfill as CK. Scanning electron microscopy (SEM) and infrared analyses revealed that two-year landfill caused considerable changes in physical forms and spectral peaks in BIO film, which was more pronounced in thin BIO (36.90 % weight loss). Yet, less changes were presented in the above analyzes in polyethylene (PE) films, and thick films damaged relatively less. MPs number was 86,829.11 n/kg in BIOt1 and 134,912.27 n/kg in BIOt2, equivalent to 2.55 and 3.72 times higher than in PEt1 and PEt2, respectively. This was closely associated with PAEs release, as soil PAEs concentration was substantially lower in PEt1 (17.60 g/kg) and PEt2 (21.43 g/kg) than in BIOt1 and BIOt2 (37.12 g/kg and 49.20 g/kg), respectively. Furthermore, maize productivity parameters were negatively correlated with the amount of MPs and PAEs. BIOt2 and PEt1 had the lowest and highest grain yield, respectively. BIO exhibited greater environmental risk and adverse effects on soil and crop productivity than PE film due to physical degradation and release of PAEs. Thickness-wise comparison exhibited that thin film residues had more adverse effect relative to thick film ones.
Asunto(s)
Ácidos Ftálicos , Contaminantes del Suelo , Suelo/química , Microplásticos/toxicidad , Plásticos/química , Polietileno/análisis , Contaminantes del Suelo/análisis , Ácidos Ftálicos/análisis , Ésteres/análisis , ChinaRESUMEN
Intensive use of low-density polyethylene (LDPE) plastic films in agro-ecosystems has raised considerable concerns due to the increasing film residues in soils. It is unclear how the increased film residues affect soil properties and crop productivity and whether biodegradable (Bio) film can substitute LDPE. To address the issue, we designed a landfill experiment with different addition levels of plastic residue into soils of maize (Zea mays L.) field from 2018 to 2019. Six treatments were arranged as PMT1-T3/BioT1-T3, representing the low, medium, and high-level application of LDPE / Bio film fragments, with no residual film, applied as CK. Results show that, soil bulk density was significantly increased from 1.19 to 1.31 g/cm3 regardless of residue types. In contrast, soil porosity was lowered from 58.03% in CK to 57.36% in Bio and 56.12% in LDPE significantly (P < 0.05). Increased residues improved soil nitrogen level and lowered the C/N ratio significantly. Also, it decreased microbial biomass C and N levels but with no change in C/N (P < 0.05). Maize yield and WUE decreased, while soil water storage increased significantly. LDPE residues affected soil properties and productivity partly lower than Bio ones did, but the negative effects of them were similar in the maize field.
Asunto(s)
Ecosistema , Suelo , Agricultura , China , Plásticos , Zea maysRESUMEN
Residual plastic film in soil destroys the soil structure and changes the normal transportation and distribution of water and nutrient. In this work, we compared experiments on soil containing residual plastic film with a control experiment to investigate how residual film affects the transportation and distribution of water and nitrate (NO3-) in wetted soil. The experiment used Mariotte bottle, water tube, and soil tank to test six levels of residual-film concentration varying from 0 to 720â¯kg/hm2 in the soil. The wetting front, soil water content, and nitrate concentrations were all measured, and the results showed that when the concentration of residual-film was less than 360â¯kg/hm2, more water and nitrate remained in the upper part of the wetted volume due to block of residual film. Excessive residues (>360â¯kg/hm2) resulted in obvious phenomenon of preferential flow, which increased the wetting distance, wetted volume, and water content in the lower part of the wetted volume and the concentration of nitrate at the boundary of the wetted volume. These results not only help us to understand the consequences of plastic-film-residues pollution in terms of water and nitrate movement, but also provide scientific support to the development and establishment of reasonable irrigation, fertilization and management systems for polluted farmland with differential mulch residual concentrations.