Introduction: Plastic materials are used in agriculture for various purposes (flooring films, irrigation tubes, cords). With time they eventually decompose into smaller particles less than 5 mm. They become the so-called microplastics. Microplastics (MPs) can be transported from wastewater treatment plants to agricultural land using wastewater or/and activated sludge. This allows the microplastics to act as a vector for the adsorbed pollutants present in the treatment plants. Due to the use of pesticides, which play an important role in the control of pests and diseases on agricultural land, microplastics are further exposed to the adsorption of pesticides. Purpose: The purpose of the master's thesis was the development of the method for following the adsorption of selected pollutants - pesticides, commonly used on agricultural land, onto microplastics, which is often present in waste waters and activated sewage sludge which is landfilled. We were following the solubility of pesticides in waters containing MPs including changable parameters: type of pesticide, its adsorption, the effect of mixing solutions, exposure to artificial wastewater, and finally the influence of pesticide retention on soil containing microplastics. Methods: The adsorption of two pesticides with different water solubility - chlorantraniprol and chlorpyrifos - was investigated in two different aqueous media: deionized water and artificially prepared waste water. We studied the retention of chlorpyrifos in the soil with respect to the amount of microplastics. The concetration of pesticides was defined applying a high-performance liquid chromatograph. Results: The adsorption of the selected pesticides did not occur in deionized water, so any conclusion was possible regarding the effects of solubility, mixing and light/darkness. In artificial wastewater, well-soluble chlorantraniprole was not adsorbed on MPs while chlorpyrifos was. In the soil experiment, we found that the light density polyethylene (LDPE) did not retained chlorantraniprole, since there was any statistically significant difference between batches. Whereas, the adsorption of chlorantraniprole depends on the content of polypropilene PP, and we found a statistical significant difference between batches containing different percentage of PP. Discussion and conclusion: The study confirmed that the adsorption of less soluble pesticide on MPs is higher and it was proven that the effect of stirring is an important parameter. The results of our research can help to assess the risk of concurrent exposure to pesticides and micro-plastics. As the area of work is new, it is more of development-nature oriented and it brings important conclusions and bases for further research into the topic.
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