Comparison of the effects of biodegradable and conventional polyester-based microplastics on soil abiotic processes

abstract

English

The properties, occurrence, and adverse effects of conventional microplastics are examined worldwide. However only few studies have focused on biodegradable microplastics (micro-bioplastics), whose abundance in environment is expected to grow continuously [1]. After the entrance to soil, the micro-bioplastics may interact with parts of soil organic matter (SOM) via weak interactions and induce the structural changes in SOM. This affects primarily the properties of SOM and secondarily also the properties of SOM water, which alters soil ecosystem functions [2]. In this study, selected abiotic soil indicators were determined for soil contaminated with polyhydroxybutyrate (PHB) microbioplastics and PET microplastics to evaluate their effect on soil. Peat was used as a model of soil organic matter. Water holding capacity of SOM, strength of water binding (evaporation enthalpy of soil water), water molecule bridges stability (demonstrated as a steep increase in heat capacity, WaMB) and content of soil aliphatic crystallites (via melting enthalpy) were determined using Differential Scanning Calorimetry (DSC) in soils dried under three different relative humidities. We have found that both kinds of microplastics decreased the strength of water binding in soil as well as the content of aliphatic crystallites. In addition, WaMB stability and water holding capacity of SOM were different for each microplastics and humidity. These results implicate that both conventional microplastics and micro-bioplastics negatively affect soil water and structure, which may consequently have an adverse effect on soil functions. This observation applies mainly for initial stages of introduction of microplastics into soil, when the microplastics interact with SOM parts and changes its supramolecular structure. In the case of micro-bioplastics, in a relative short period, the soil microorganisms start to biodegradation which assumingly leads to different effect comparing to conventional microplastics. Bioplastics are considered as a promising alternative for conventional plastics in agriculture, however more research in this area is required before any worldwide application on agricultural soil.

PET, PHB, soil, soil organic matter, water molecule bridges

FOJT, J.; DENKOVÁ, P.; KUČERÍK, J.

20. 7. 2021

Central and Eastern European Committee for Thermal Analysis and Calorimetry (CEEC-TAC)

Rumunsko

978-606-11-7861-2

Book of abstracts of the 6th Central and Eastern European Conference on Thermal Analysis and Calorimetry (CEEC-TAC6) and 15th Mediterranean Conference on Calorimetry and Thermal Analysis (Medicta2021).

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http://www.ceec-tac.com/download.php?f=../download/BoA%20CEEC-TAC6%20Medicta2021.pdf