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The occurrence and fate of microplastics in Swiss arable soils

English title The occurrence and fate of microplastics in Swiss arable soils
Applicant Bigalke Moritz
Number 182672
Funding scheme Project funding (Div. I-III)
Research institution Geographisches Institut Universität Bern
Institution of higher education University of Berne - BE
Main discipline Pedology
Start/End 01.02.2019 - 31.07.2022
Approved amount 266'109.00
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Keywords (5)

contaminant transport; microplastic; analytical method; contaminant source; soil

Lay Summary (German)

Lead
Plastikteilchen, die kleiner als 5 mm sind werden als Mikroplastik bezeichnet. Wenn Mikroplastik in der Umwelt gelangt, kann es von Organismen aufgenommen werden und diese schädigen. Bisher gibt es kaum Untersuchungen von Mikroplastik in Böden. Dabei kann z.B. durch Littering, Reifenabrieb oder die Verwendung von Klärschlamm, Kompost oder Folien in der Landwirtschaft viel Plastik in den Boden gelangen. Landwirtschaftliche Böden sind dabei von besonderem Interesse, weil dort der Grossteil der Lebensmittel produziert wird und Mikroplastik im Boden die Lebensmittelproduktion negativ beeinträchtigen könnte.
Lay summary

Inhalt und Ziel des Forschungsprojektes
Das übergeordnete Ziel des Projekts ist ein besseres Verständnis über das Vorkommen und das Verhalten von Mikroplastik im Boden. Im Detail werden wir (i) die bestehenden Methoden verbessern um Mikroplastik im Boden zu messen, (ii) landwirtschaftliche Böden mit bekannter Klärschlamm, Kompost und Folienanwendung untersuchen und (iii) die Tiefenverlagerung von Mikroplastik im Boden und einen möglichen Transfer ins Grundwasser erforschen.

Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojekts
Unsere Arbeit wird wichtige Informationen über das Vorkommen, die Quellen und den Transport von Mikroplastik in landwirtschaftlichen Böden der Schweiz liefern. Die Ergebnisse werden dazu beitragen abzuschätzen, ob Mikroplastik in landwirtschaftlichen Böden langfristig die Lebensmittelproduktion stören oder in das Grundwasser gelangen kann. Damit bilden sie eine Grundlage für das Monitoring von Mikroplastik und die politische Entscheidungsfindung für eine mögliche Verminderung der Mikroplastik Freisetzung.    

Direct link to Lay Summary Last update: 18.02.2019

Responsible applicant and co-applicants

Employees

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Abstract

Significant amounts of microplastics (MP) end up in soils by littering, sewage sludge and compost application, the use of plastic foils in agriculture, irrigation, atmospheric deposition and many other sources. These MP are known to have toxic effects on soil organisms, and to enter the human food chain. However, knowledge about the occurrence of MP in soils is still very limited. This is mostly due to the fact that research in this new field has just started. Furthermore, transport and toxicity studies on MP were mostly performed in laboratory experiments and actual field data are scarce. Therefore, it is impossible to know how many MP to expect in soils under different land use systems. Here especially agricultural soils seem to be of intrest because MP could effect the quantity (reduced fertility) and quality (MP transfer to food) of produced food. Additional, sewage sludge application and agricultural practices such as plastic mulching, compost application and irrigation can be considered to bring significant ammounts of MP to the system. Thus we will focus on arable soils in this study. The lack of data about MP in soils is also due to the fact that there is no method available which allows for the full characterization of MP in soils (shape, size and type of plastic). The general research question of the proposed project is: What is the occurrence and fate of MP in Swiss arable soils? To answer this questions we aim to 1) develop of a method to fully quantify and characterize MP in soil samples, to allow for a reliable and complete characterization of MP in soils, 2) characterise the sources and MP and quantify its influence on soil MP characterisation in arable soils, 3) investigate the influence of soil properties and preferential flow on MP transport in arable soils. To follow these aims I planed three workpackages.Work package 1: The development of a method which allows for the full characterisation of all important MP in soils. All methods which exist for the analysis of MP in soils all have severe limitations when it comes to preserve MP characteristic such as size and shape of particles, or are not suitable for the analysis of important MP such as polyethylene terephthalate. We aim to improve our existing method for MP analysis, by optimizing the removal of soil organic matter and test the extraction efficiency of MP in soils with different properties and a long history of MP contamination.Work package 2: A study of the most important sources of MP in agriculture. We will analyse MP concentrations and characteristics of different sources of MP and concentration and characteristics of arable soils treated with these sources. The results will allow to assess the influence of the treatment on soil MP concentration and possible future development of MP concentrations in soils. Furthermore, we will analyse if the different sources produce characteristic MP patterns in soil, which may allow for source identification in arable soils with unknown management history.Work package 3: A study about the influence of soil properties on the depth transport of MP in agricultural soils. Soil properties such as the pH, texture and organic matter content does not only influence the soil biology and thus affect bioturbation, but also physical formation of macropores (e.g. swelling/shrinking behaviour) of soils. As MP transport has been reported to occur along preferential flow path in soils, soil properties may be an important factor for MP transport in soil.The experimental work will be conducted by one PhD student, which will work for 3.5 years on the topic. The results will be essential for a future reliable analysis of MP in soils, to judge the risk associated with MP in arable soils, to reduce further accumulation and to understand the transport of MP. These data will be the basis for a scientific, public and political debate about MP in soils and might induce actions to reduce MP emission to soils.
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