Adsorpcija fungicida na biorazgradljive folije v kmetijskih tleh

Merkun, Ines (author), Bavcon Kralj, Mojca (mentor), Ugrinović, Kristina (comentor)

Uvod: Mikroplastika, manjša od 5 mm, predstavlja resno tveganje za kopenske in vodne ekosisteme. Uporaba plastičnih folij v kmetijstvu prispeva k onesnaževanju z mikroplastiko, ki lahko adsorbira hidrofobna organska onesnaževala. Ta onesnaževala različno, večinoma negativno, vplivajo na strukturo tal, rastline in podtalnico ter posledično ogrožajo okolje in zdravje ljudi. Namen: Namen magistrskega dela je preučiti adsorpcijsko ter desorpcijsko sposobnost za zadrževanje azoksistrobina na novih in staranih biorazgradljivih folijah (sestave poli(butilen adipat-ko-tereftalat) / polimlečna kislina - PBAT/PLA in termoplastični škrob - TPS) v primerjavi s klasičnimi polietilenskimi (PE) folijami. Metode dela: V laboratorijskem poskusu smo določili koncentracije adsorbiranega in desorbiranega fungicida na biorazgradljivi (PBAT/PLA, TPS) in klasični (PE) mikroplastiki. Delež adsorpcije smo določili z mešanjem vzorcev, ki so vsebovali izbrano mikroplastiko in raztopino s fungicidom, medtem ko smo delež desorbiranega fungicida določili z mešanjem vzorcev, ki so vsebovali mikroplastiko in raztopino, ki fungicida ni vsebovala. Koncentracije fungicida, adsorbirane na delce mikroplastike in desorbirane iz njih, smo izmerili s tekočinsko kromatografijo z detektorjem na niz diod (HPLC/DAD). Za statistično obdelavo podatkov smo uporabili t-teste, s katerimi smo preverjali statistično značilne razlike med izbranimi pari vzorcev. Rezultati: S statistično analizo rezultatov smo ugotovili, da biorazgradljive folije izkazujejo visoko adsorpcijsko (> 85 %) in desorpcijsko sposobnost, ne glede na njihovo starost. V nasprotju s tem je adsorpcija na običajnih PE folijah nizka, medtem ko je desorpcija primerljiva z biorazgradljivimi folijami in v vseh primerih nizka. Staranje PE folij povečuje njihovo adsorpcijsko (iz 0 % na > 22 %) in desorpcijsko (iz 0 % na 10 %) sposobnost, kar pa ne velja za biorazgradljive folije. Pri slednjih se adsorpcija s starostjo le minimalno poveča iz 87 % na 91 %, medtem ko pri desorpciji s starostjo opazimo zmanjšanje deleža desorbiranega fungicida iz 10 % na 8 %. Razprava in zaključek: Z raziskavo smo potrdili, da se fungicid adsorbira na delce mikroplastike in desorbira z njih. Na adsorpcijo najbolj vpliva vrsta mikroplastike, medtem ko je vpliv starosti manj izrazit. Na desorpcijo pa vplivata tako vrsta kot starost mikroplastike. Z nalogo smo prispevali k boljšemu razumevanju vpliva različnih vrst mikroplastike na adsorpcijo in desorpcijo fungicida, pri čemer smo še posebej izpostavili primerjavo med biorazgradljivimi in klasičnimi folijami. Raziskava predstavlja izhodišče za nadaljnje študije o vplivu različnih fungicidov na adsorpcijo mikroplastike ter predlaga širitev spektra raziskovanih vrst mikroplastike, vključno s preučevanjem dolgoročnih učinkov staranja mikroplastike v realnih terenskih razmerah.

• Language: Slovenian
• Keywords: biorazgradljiva mikroplastika, kmetijska tla, fungicid, adsorpcija, desorpcija
• Work type: Master's thesis/paper
• Organization: ZF - Faculty of Health Sciences
• Year: 2024
• PID: 20.500.12556/RUL-166185
• Publication date in RUL: 23.12.2024

Secondary language

• Language: English
• Title: Adsorption of fungicide on biodegradable films in agricultural soils

Abstract

Introduction: Microplastics smaller than 5 mm pose a serious risk to terrestrial and aquatic ecosystems. The use of plastic films in agriculture contributes to microplastic pollution, which can adsorb hydrophobic organic pollutants. These pollutants have various, mostly negative, effects on soil structure, plants and groundwater, and consequently pose a threat to the environment and human health. Purpose: The aim of this MSc thesis is to investigate the adsorption capacity and desorption retention capacity of azoxystrobin on new and aged biodegradable films (poly(butylene adipate-co-terephthalate) / polylactic acid - PBAT/PLA and thermoplastic starch - TPS compositions) in comparison with conventional polyethylene (PE) films. Methods: In a laboratory experiment, the concentrations of adsorbed and desorbed fungicide on biodegradable (PBAT/PLA, TPS) and conventional (PE) microplastics were determined. The adsorption fraction was determined by mixing samples containing the selected microplastic and a solution containing the fungicide, while the desorbed fungicide fraction was determined by mixing samples containing the microplastic and a solution containing no fungicide. The concentrations of fungicide adsorbed to and desorbed from the microplastic particles were measured by liquid chromatography with an array of diode array detector (HPLC/DAD). For statistical treatment of the data, t-tests were used to test for statistically significant differences between the selected pairs of samples. Results: Statistical analysis of the results showed that biodegradable films exhibit high adsorption (> 85%) and desorption capacity, regardless of their age. In contrast, adsorption on conventional PE films is low, while desorption is comparable to biodegradable films and low in all cases. Ageing of PE films increases their adsorption (from 0% to > 22%) and desorption (from 0% to 10%) capacity, which is not the case for biodegradable films. For the latter, adsorption increases only marginally with age from 87% to 91%, while for desorption with age a decrease in the proportion of fungicide desorbed from 10% to 8% is observed. Discussion and conclusion: The study confirmed that fungicide adsorbs to and desorbs from microplastic particles. The adsorption is most influenced by the type of microplastic, while the influence of age is less pronounced. However, desorption is influenced by both the type and the age of the microplastic. This thesis has contributed to a better understanding of the influence of different types of microplastics on the adsorption and desorption of fungicide, with particular emphasis on the comparison between biodegradable and conventional films. The study provides a starting point for further studies on the effect of different fungicides on the adsorption of microplastics and suggests broadening the range of microplastic types investigated, including the study of the long-term effects of ageing of microplastics under realistic field conditions.

• Keywords: biodegradable microplastics, agricultural soils, fungicide, adsorption, desorption