There is no doubt that among many anthropogenic environmental stresses that are threatening the future of life on our planet, plastic pollution is one of the topics on top of the list. Since the beginning of the 21st century, there has been an accelerating trend in the research concerning the detection of microplastics and their negative impacts on the aquatic ecosystems and marine environments. However, studies concerning the role of plastics in polluting the terrestrial ecosystems, soils and plants are limited and numerous questions still need to be addressed.
The aim of this session is to bring together contributions on novel measurement techniques or analytical approaches to observe, detect or quantify plastics in soil-plant systems in any observational or process scales. Any studies highlighting how nano and microplastics accumulate or are transported in soil, contaminate groundwater, change chemical properties of the soil, affect soil biota or is adsorbed by plants roots are welcome. Presentations addressing how microplastics alter the rhizosphere condition by affecting the biological, chemical and physical properties of the soil are appreciated. One main purpose of this session is to gather researchers from the related disciplines to exchange experiences and finding innovative solutions for the current unknown problems and highlight the future research needs of the potential impacts of microplastics on soils and plants.

Co-organized by HS12
Convener: Mahyar Naseri | Co-conveners: Peter Fiener, Melanie Braun, Christina Bogner, Andrea Carminati, John Quinton, Wolfgang Durner
| Attendance Tue, 05 May, 08:30–10:15 (CEST)

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Chat time: Tuesday, 5 May 2020, 08:30–10:15

Chairperson: Peter Fiener
D2424 |
Linda Heerey, John O'Sullivan, Michael Bruen, Ian O'Connor, Anne Marie Mahon, Heather Lally, Sinéad Murphy, Róisín Nash, and James O'Connor

The prevalence of microplastic (MP), typically characterised as polymeric materials of particle (1 µm - 5 mm) are an increasing concern in our marine and freshwater systems. International research efforts have mainly focused on the abundance, characteristics and implications of plastic pollution in marine settings, with the transport and fate of plastics in terrestrial and freshwater systems being less well understood. The pathway from land to sea is significant in the Irish context given the widespread use of MP rich biosolids for soil conditioning in agricultural lands.  Biosolids represent the treated sewage sludge produced in the wastewater treatment process, ~80% of which nationally is used in land treatment. Given the combined nature (storm and foul water conveyed and treated together) of the drainage network in many parts of Ireland, coupled with evidence that 90% of MPs in influent waters are retained in these sewage sludges, the application of sludges to agricultural lands represents a considerable MP input on these land systems. MPs can potentially be moved or transported from these terrestrial systems through atmospheric escape, and in hydrological pathways through the soil matrix and/ or in direct overland runoff.

Here we report on an experimental investigation exploring the transport potential of biosolid MPs through infiltration and percolation processes in agricultural fields.  A drainage experiment was initially undertaken in loosely packed vertical sand columns. Polymers of different type (PVC, PET and LDPE), size (<150 µm, 150-300 µm) and in both virgin and weathered states were seeded on the surface of saturated sand columns and subjected to simulated rainfall of varying intensity for different durations (up to 20 hours).  Each test was conducted in triplicate with columns draining under gravity and water samples were collected from their base. The results indicate limited MP mobility given all seeded MPs were recovered in the surface layers (top 5 cm).  To confirm these findings, a further investigation involving the extraction of 2 m deep cores from a down-slope transect of an agricultural field was undertaken. This field had been treated with thermally dried wastewater treatment plant sludge annually for ~20 years. The dispersion and depth of MPs were observed through laboratory testing and through Itrax core scanning.  Results indicated that the majority of MPs (mostly fibers) were retained in the upper c. 30 cm (plough zone) of each core with penetration of biosolid MPs to depths below this being considerably more limited.  Concentrations of MPs found within the plough zone were lower than expected (0.14 to 0.03 MP per gram of soil), suggesting that vertical migration through the soil matrix of biosolid MPs is not a significant hydrological transport pathway.

How to cite: Heerey, L., O'Sullivan, J., Bruen, M., O'Connor, I., Mahon, A. M., Lally, H., Murphy, S., Nash, R., and O'Connor, J.: Investigation into the Vertical Migration of Microplastic in Agricultural Soil, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20480, https://doi.org/10.5194/egusphere-egu2020-20480, 2020.

D2425 |
Andreas Cramer, Ursula Bundschuh, Pascal Bernard, Mohsen Zarebanadkouki, and Andrea Carminati

Soils are the largest sink of microplastic particles (MPP) in terrestrial ecosystems. However, there is little knowledge on the implication of MPP contaminating soils. In particular, we don’t know how MPP move and, on the other hand, how they affect soil hydraulic properties and soil moisture dynamics.

Among the expected effects of MPP on soil hydraulic properties is the likelihood that MPP enhances soil water repellency. This emerges from (1) the MPP surface chemical properties as well as (2) their surface physical properties like size and shape. Here, we tested mixtures of MPP and a model porous media. The Sessile Drop Method was applied and apparent contact angles were measured. We are able to show enlarged contact angles with rising concentrations of MPP. Already in relatively low concentrations of MPP the contact angels exhibit a steep increase and are rapidly reaching areas of super-hydrophobicity. Furthermore, we provide the physical explanation of the apparent contact angles resulting from the three-phase contact line between solid composite surfaces, water and air. The considered modes of a droplet lying on a surface are Wenzel, Cassie-Baxter and Young. The goal here was to differentiate between the involved surfaces building up the apparent contact angle and to pin down the impact of MPP in these systems.

Thinking about the implications of these results, an increased water repellency alters soil hydraulic properties towards less water content resulting in a shift in the water retention curve. Less water in soils especially at sites of high MPP concentrations leads to a limitation of degradation of MPP by hydrolysis. Additionally, microorganisms themselves and their enzymes cannot migrate in the liquid phase towards the MPP even elongating the process of natural purification.

How to cite: Cramer, A., Bundschuh, U., Bernard, P., Zarebanadkouki, M., and Carminati, A.: Microplastic enhances water repellency of soils, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10362, https://doi.org/10.5194/egusphere-egu2020-10362, 2020.

D2426 |
Taotao Lu, Benjamin S. Gilfedder, and Sven Frei

With the increasing use of nanoplastic products in our daily life, these particles will invariably enter into the subsurface environment. It is, therefore, vital to understand the transport and retention of nanoplastic particles in groundwater systems. Surface charge heterogeneity is one of the basic chemical-physical characteristics of aquifer materials, but little research has been conducted on this topic. This study aimed to understand how the interaction between the porous media, solution chemistry, and NP surface charge influences the transport and retention of PS-NPs in the subsurface. 25 mg/L polystyrene nanoplastic particles (PS-NPs) were injected into columns packed with iron oxyhydroxide-coated sand. In addition, factors such as the content of iron oxyhydroxide-coated sand (λ), pH, ionic strength (IS), and cation valence were systematically studied. DLVO theory was used to evaluate the interactions between PS-NP and the porous media. By comparing the breakthrough curves (BTCs) of PS-NPs, it was clear that all these variables exerted a significant influence on the mobility of PS-NPs in the columns. These effects could be explained by the following: Firstly, by applying the DLVO theory, it was possible to model the electrostatic interaction between quartz sand and PS-NPs. For instance, at different IS (NaCl), the maximum energy barrier (Φmax) decreased with an increase in IS, which meant PS-NPs could more easily overcome the energy barrier to deposited on the sand surface at higher IS. Secondly, the positively charged iron oxyhydroxide coating provided additional favorable deposition sites for negatively charged PS-NPs. However, when the pH of the solution exceeded the iron oxyhydroxide pHpzc (~pH 9), the iron coating became negative and increased the mobility of PS-NPs. Finally, bridging agents, such as Ca2+ and Ba2+, resulted in the significant deposition of PS-NPs on the sand due to the bridging effect connecting the porous media and PS-NPs through the O-containing functional groups on both plastic and mineral surfaces. This study provides a better understanding of how the charge heterogeneity on aquifer materials and groundwater hydrochemistry affect the transport of PS-NPs in aquifers.

How to cite: Lu, T., Gilfedder, B. S., and Frei, S.: Transport and retention of nanoplastic particles in saturated columns packed with iron oxyhydroxide-coated sand, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2548, https://doi.org/10.5194/egusphere-egu2020-2548, 2020.

D2427 |
Davey Jones and David Chadwick

Microplastics represent an emerging threat to terrestrial ecosystems, however, our understanding of the fate and behaviour of microplastics in the plant-soil system remains poor. In this replicated, field-scale study we added microplastics (low density polyethylene) to soil at different dose rates representing contamination levels ranging from 0 to 10 t ha-1. These levels were chosen to cover both agricultural and urban contamination levels. Over a 12 month period, we studied a range of chemical, physical and biological soil quality indicators and wheat productivity to evaluate the impact of microplastics on the delivery of soil-related ecosystem services. Overall, we found little evidence to suggest that microplastics affect plant growth even at high dose rates. In contrast, microplastics had a significant impact on soil quality. The use of PLFA profiling and 16S metabarcoding of the bacterial and archaeal community, revealed changes in key microbial taxa at high microplastic doses. In addition, physiological profiling of the microbial community using lipidomics, untargeted metabolomics and targeted nitrogen metabolomics (using GC-MS platform) revealed significant shifts in microbial physiology. No appreciable effect of microplastics was seen on soil N and P dynamics, earthworm abundance or greenhouse gas emissions (CO2, N2O and CH4). Overall, our results suggest that microplastics do induce changes in soil quality, but that this has little overall effect on the delivery of key soil-related ecosystem services. These results contrast strongly with experiments performed in laboratory mesocosms where microplastics negatively affected plant growth and soil quality, and highlight the need to study the impact of microplastics at the field scale over longer timescales.

How to cite: Jones, D. and Chadwick, D.: Microplastic-Induced Changes in Soil Quality and Functioning: Field Scale Trials, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11584, https://doi.org/10.5194/egusphere-egu2020-11584, 2020.

D2428 |
Frederick Büks, Loes van Schaik, and Martin Kaupenjohann

The ubiquitous accumulation of microplastic particles across all global ecosystems comes along with the uptake into soil food webs. In this work, we evaluated studies on passive translocation, active ingestion, bioaccumulation and adverse effects within the phylogenetic tree of multicellular soil faunal life. The representativity of these studies for natural soil ecosystems was assessed using data on the type of plastic, shape, composition, concentration and time of exposure.

Available studies cover a wide range of soil organisms, with emphasis on earthworms, nematodes, springtails, beetles and lugworms, each focused on well known model organisms. Most of the studies applied microplastic concentrations similar to amounts in slightly to very heavily polluted soils. In many cases, however, polystyrene microspheres have been used, a combination of plastic type and shape, that is easily available, but do not represent the main plastic input into soil ecosystems. In turn, microplastic fibres are strongly underrepresented compared to their high abundance within contaminated soils. Further properties of plastic such as aging, coating and additives were insufficiently documented. Despite of these limitations, there is a recurring pattern of active intake followed by a population shift within the gut microbiome and adverse effects on motility, growth, metabolism, reproduction and mortality in various combinations, especially at high concentrations and small particle sizes.

For future experiments, we recommend a modus operandi that takes into account the type, shape, grade of aging and specific concentrations of microplastic fractions in natural and contaminated soils as well as long-term incubation within soil mesocosms.

How to cite: Büks, F., van Schaik, L., and Kaupenjohann, M.: What do we know about how the terrestrial multicellular soil fauna reacts to microplastic?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18474, https://doi.org/10.5194/egusphere-egu2020-18474, 2020.

D2429 |
Yueling Qi, Xiaomei Yang, Esperanza Huerta Lwanga, Paolina Garbeva, and Violette Geissen

In the last decades, the use of plastic mulch film in (semi-) arid agricultural regions has strongly increased. Plastic residues from mulching remain and accumulate in soil that can lead to serious environment problems. Biodegradable plastic mulch films were produced as environmentally friendly alternative for solving plastic pollution in agricultural land. However, the effects of polyethylene and biodegradable mulch film residues on soil-plant system are largely unknown.

In this PhD project, we performed a series of experiments to assess the effects of low density polyethylene (LDPE) and biodegradable plastic (Bio, made of polyethylene terephthalate, polybutylene terephthalate, pullulan) with macro- (5 mm2, Ma) and micro- (50 µm-1 mm, Mi) sizes on wheat growth, rhizosphere microbiome, soil physicochemical and hydrological properties and soil suppressiveness. The results showed that plastic residues presented negative effects on both above- and below-ground  parts for both vegetative and reproductive development of wheat. We also identified significant effects of Bio and LDPE plastic residues on the rhizosphere bacterial communities and on the blend of volatiles emitted in the rhizosphere. Tested with a gradient in concentration of plastic residues (0, 0.5%, 1% and 2% w/w), soil physicochemical and hydrological properties nonmonotonically responded to residual amount of plastic debris in the soil. Lastly, although we did not observe effects of plastic residues on disease infection in our experiment, we anticipated that soil suppressiveness and other soil functions would be affected with the presence of plastics in soil.

Overall, our study provides evidence for impacts of plastic residues on the soil-plant system, suggesting urgent need for more research examining their environmental impacts on agroecosystems.

How to cite: Qi, Y., Yang, X., Huerta Lwanga, E., Garbeva, P., and Geissen, V.: Microplastics in agroecosystem – effects of plastic mulch film residues on soil-plant system, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13733, https://doi.org/10.5194/egusphere-egu2020-13733, 2020.

D2430 |
Fanrong Meng

Plastic mulching is a common farming practice in arid and semi-arid regions. Inappropriate disposal of plastic films can lead to the contamination of macroplastics (MaPs) and microplastics (MiPs) in the soil. To study the effects of plastic mulching on the contamination of soil with MaPs and MiPs and the role of farm management on this contamination, research was done on two farming systems in Northwest China, where plastic mulching is intensively used. Farming in Wutong Village (S1) is characterized by small plots and low-intensity machinery tillage while farming in Shihezi (S2) is characterized by large plots and high-intensity machinery tillage. Soils were sampled to a depth of 30 cm and analysed. The results showed that MaPs ranged from 30.3 kg·ha-1 to 82.3 kg·ha-1 in S1 and from 43.5 kg·ha-1 to 148 kg·ha-1 in S2. The main macroplastics  size categories were 2-10 cm2 and 10-50 cm2 in S1 and  < 2 cm2 and 2-10 cm2 in S2. In S1, we found that 6-8 years of continuous mulching practice resulted in the accumulation of more MaPs as compared to the use of intermittent mulching over the span of 30 years. For S2,  6 to 15 years of plastic mulching use led to MaPs accumulation in fields but from 15 to18 years, the MaPs number and content in soils dropped due to further fragmentation of the plastic and its dispersal into the environment. MiPs were mainly detected in fields with > 30 years of mulching use in S1 and discovered in all fields in S2, this indicated that  long-term cultivation and high-intensity machinery tillage could lead to more severe microplastic pollution. These results emphasized the impacts of  farm management on the accumulation and spread of MaPs and MiPs in the soil and regulations are needed to prevent further contamination of the soil.

How to cite: Meng, F.: Effect of plastic mulching on the accumulation and distribution of macro and micro plastic particles in the soil - A case study of two farming systems in North West China , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5580, https://doi.org/10.5194/egusphere-egu2020-5580, 2020.

D2431 |
Rachel Hurley, Jill Crossman, Theresa Schell, Andreu Rico, Martyn Futter, Marco Vighi, and Luca Nizzetto

There is a paucity of data regarding the sources and fate of microplastics in agricultural settings. This is despite indication that these environments may receive significant contributions of microplastics from a range of inputs. Several studies have documented the enrichment of sewage sludge by microplastic particles as a result of wastewater treatment processes. In many countries, sludge is applied to agricultural soils as a soil conditioner. Based on the extent of application and microplastic loads in sludge material, it is expected that sludge application to land represents a considerable release pathway for microplastic particles to the environment. The fate of these particles across spatial and temporal scales is, however, unknown. This includes the potential for the propagation of contamination to connected aquatic systems and beyond.

The Water JPI-funded IMPASSE project addresses significant gaps in our understanding of microplastic contamination in agricultural systems. As part of this project, two case study locations in contrasting environments were selected for study: the semi-arid Henares catchment in central Spain and the humid continental Beaver and Orillia catchments in the Lake Simcoe watershed in Ontario, Canada. Agricultural fields subjected to different sludge application treatments (timing and origin of material) were assessed for microplastic contamination through repeat soil core sampling. This was coupled with runoff experiments using modified Pinson collectors to track the mobilisation of sewage sludge-derived particles from soils. Laboratory analysis was performed according to Hurley et al. (2018). Thorough characterisation of all microplastics particles down to a lower size limit of 50 µm was achieved, including particle size, morphology, polymer type, and estimated mass. Microplastic loads in soils increased following sludge application. The dynamics of contamination from soil core analyses show complex spatio-temporal patterns of accumulation and vertical and lateral transport of particles. Through the use of experimental runoff plots, the mobilisation of microplastic particles from agricultural soils has been documented for the first time. Preferential accumulation and transport of different particle morphologies – e.g. fibres vs fragments – was also observed. These findings form the basis of innovative modelling work in the case study catchments to predict dynamics of agricultural microplastic contamination and subsequent transfer to aquatic environments.

How to cite: Hurley, R., Crossman, J., Schell, T., Rico, A., Futter, M., Vighi, M., and Nizzetto, L.: Fate of microplastic particles in agricultural soil systems: Transport and accumulation processes in contrasting environments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16710, https://doi.org/10.5194/egusphere-egu2020-16710, 2020.

D2432 |
Elke Brandes, Martin Henseler, and Peter Kreins

The topic of microplastic (MP) contamination in agricultural soils has recently gained attention in science and society. Experimental studies indicate that microplastic (i.e., plastic particles < 5mm in size) can have negative effects on soil physical properties and ecology, but an actual impairment of soil functions at current concentration levels in agricultural soils has yet to be shown. Nevertheless, the continuous production of single-use plastic and low degradation rates implicate an accumulative effect of MP in the environment that calls for more research on the amounts and impacts of this contaminant.  The most discussed agricultural sources for microplastic contamination of cropland are biosolids (e.g., sewage sludge and compost) applied as soil amendment to fields, as well as tarps used in plasticulture. However, knowledge about how much microplastic is accumulating in agricultural soils is scarce. Only a few analytic quantification studies have been published so far. Existing estimates from production and consumption statistics have been performed at national level, but as of yet, spatially explicit regional quantification of microplastic immissions into agricultural soils are missing in the scientific literature.

Using data on microplastic concentrations in biosolids from the literature in combination with national and regional statistics on sewage sludge, compost and organic waste production, as well as specialty crop areas, we estimated annual microplastic immissions into agricultural soils in Germany at NUTS3 (county) resolution. This top-down modeling approach allowed us to identify hot spots where potential microplastic concentration is high. 

Although these estimates are based on limited data availability, they yield information on the spatial distribution of potential microplastic contamination in agricultural soils in Germany. Our results provide first indications about locations where detailed soil analysis could be useful to investigate in situ processes and impacts. The methodology can be applied to other regions and continuously adapted when more knowledge on relevant sources, transport, accumulation, and degradation rates of microplastic in soils is gained in the future. 

How to cite: Brandes, E., Henseler, M., and Kreins, P.: Estimating regional distributions of agricultural microplastic immissions into soils - a top-down modeling approach for Germany, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20054, https://doi.org/10.5194/egusphere-egu2020-20054, 2020.

D2433 |
Raphael Pinheiro Machado Rehm and Peter Fiener

Agricultural soils play a key role as sink of microplastic (MP) coming from different sources, especially via the application of sewage sludge, compost, the decay of plastic mulch, and tire ware particles along streets. However, the effectiveness of this sink might be substantially reduced in areas subjected to water erosion. The aim of this study is to determine the transport potential of MP during water erosion events on agricultural land. More specifically, we are interested if MP is preferentially transported or if it is attached or associated to soil minerals and aggregates leading to a more conservative transport behavior. The transport behavior is studied based on a series of plot rainfall simulations on a silty loam (16% sand, 59% silt, 25% clay; 1.3% OC) and a loamy sand soil (72% sand, 18% silt, 10% clay; 0.9% OC) located at experimental farms in Southern Germany. To simulate heavy rain on dry and wet soil a sequence of two simulations with a gap of 30 min was performed for 30 min each (rainfall intensity 60 mm/h) on each of the four plots (2 m x 5 m). The simulations are repeated in spring and autumn for two years. Before the beginning of the experiment all plots were prepared, adding fine (53-100 μm) and coarse (250-300 μm) microplastic (high density polyethylene) in a topsoil (< 10 cm) concentration of 10 g/m-2 and 50 g m-2. The different soils show similar mean runoff rates for the dry run (2 l min-1), whereas the wet run produced slightly higher rates on the silty loam (5.5 l min-1) compared to the loamy sand soil (4 l min-1). In contrast, MP erosion and transport under the loamy sand was more selective, leading to MP enrichment for the first set of experiments of a factor of 3 to 20, compared to MP under silty loam with an enrichment factor of 0,4 to 0,8. The results from the first set of rainfall simulations clearly underlines the selective nature of MP erosion and transport leading to a disproportionate loss of MP from eroding sites into inland waters. The degree of MP enrichment in surface runoff is heavily depending on soil texture and especially moisture status at the beginning of an erosive rainfall event. Further investigations regarding more long-term MP enrichment effects depending on MP association to soil minerals and aggregates are under preparation.

How to cite: Pinheiro Machado Rehm, R. and Fiener, P.: Soil erosion as pathway of microplastic transport from agricultural soils to inland waters, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1954, https://doi.org/10.5194/egusphere-egu2020-1954, 2020.

D2434 |
Hannes Laermanns, Katharina Luise Müller, Martin Löder, Ramona Ehl, Julia Möller, and Christina Bogner

Since the introduction of synthetic polymers into the global material cycle, increasing amounts of microplastics have been deposited in soils. In contrast to their impact on marine environments, only little is known about the influence of these long-term contaminants on terrestrial ecosystems in general and on physical and chemical soil properties in particular. First studies highlight that microplastic particles might attach to and clog especially smaller than 30 µm pores which are crucial for the hydraulic conductivity and therefore the water flow of soils (Zhang et al., 2019, doi:10.1016/j.scitotenv.2019.03.149).

In our study, we analyse the effects of microplastic particles on vertical water flow in soil columns. In infiltration-drainage experiments, we contrast water flow in soil columns with and without microplastic particles. A bromide tracer is used to compare the arrival times of the wetting fronts and the tracer fronts, and water flow is characterized using the viscous flow approach (e.g. Bogner & Germann, 2019, doi:10.2136/vzj2018.09.0168). We show first results on how microplastic particles may affect the vertical water flow in soils and the breakthrough of the tracer.

How to cite: Laermanns, H., Müller, K. L., Löder, M., Ehl, R., Möller, J., and Bogner, C.: Effects of microplastic particles on vertical water flow in soil columns, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9637, https://doi.org/10.5194/egusphere-egu2020-9637, 2020.

D2435 |
Sascha Müller, Tonci Balic-Zunic, and Nicole R. Posth

In terrestrial environments soils are hypothesized sinks for plastic particles. Nonetheless, due to the existence of preferential flow paths as well as a variety of geochemical and microbiological processes, this sink may only be temporary. A vertical translocation from soils to groundwater aquifers eventually occurs along different pathways. In these conditions Nanoplastic transport characteristics are similar to colloidal transport behavior. Therby the magnitude of plastic transport is eventually governed by complex interplay between the particle with its surrounding media (particle-particle, particle-solvent, particle- porous media) masked by different hydro-geochemical and microbiological conditions. The physical entrapment of particles (straining) may be significant when the particle diameter exceeds 5% of the median grain size diameter. Below that size additional electrostatic, van der Waals or steric interaction become increasingly important.

We present a preliminary dataset on the interaction between Nano-sized Polystyrene (PS) with different surface coatings and a variety of common minerals occurring in groundwater aquifers under the presence of Natural Organic Matter (NOM). The reference aquifer material is based on the Danish subsurface structure of Quaternary and Miocene aquifer material, e.g. quartz, calcite and pyrite among others. In our study, batch scale interactions are up-scaled in column flow and transport experiments, simulating different groundwater aquifer flow conditions in the presence of selected minerals and NOM.

This aims to clarify transport behavior of plastic pollutant in the subsurface environment. Furthermore, it serves as guide in qualitatively assessing and quantifying the vulnerability of groundwater aquifers to Nanoplastic pollution.

How to cite: Müller, S., Balic-Zunic, T., and Posth, N. R.: Transport of Nanoplastic under groundwater aquifer flow and transport conditions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19717, https://doi.org/10.5194/egusphere-egu2020-19717, 2020.

D2436 |
Nicolas Beriot, Raul Zornoza, Paul Zomer, Onurcan Ozbolat, Eva Lloret, Isabel Miralles, Raúl Raúl Ortega, Esperanza Huerta Lwanga, and Violette Geissen

Plastic mulch is widely used in agriculture to decrease the water evaporation, increase the soil temperature, or prevent weeds. Most plastic mulches are made of highly resistant Low Density Polyethylene (LDPE). The incomplete removal of polyethylene mulch after usage causes plastic pollution. Pro-oxidant Additive Containing (PAC) and “biodegradable” (Bio) plastics were developed to avoid the need of plastic removal while preventing the plastic debris accumulation. In conventional agriculture, the use of pesticides releases substances which can be sorbed to soil particles and plastic debris. Pesticides and their residues may affect the soil microbial community. Some microbial groups are capable of using applied pesticide as a source of energy and nutrients to multiply, whereas the pesticide may be toxic to other organisms. Little is known about the long term effects of plastic debris accumulations in relation with pesticides residues. We studied 36 parcels in commercial farms, either organic or conventional, where plastic mulch has been used for 5 to 20 years in Cartagena’s country side (SE Spain). We compared the macro and micro plastic debris contents, pesticides residue levels, soil physiochemical properties in the soil surface among all parcels. Eighteen insecticides, 17 fungicides, and 6 herbicides were analysed with LC-MS/MS and GC-MS/MS systems. The ribosomal 16S and ITS DNA variable regions were sequenced to study shifts in bacterial and fungal communities, respectively. We found accumulation of plastic debris in all soil samples, plastic contents being higher in soils from organic farms. The average plastic concentration  in both managements was 0.20±0.26 g/kg of plastic debris. Soils under conventional management contained on average more than 6 different pesticide residues and an overall pesticides  concentration of 0.20±0.18 mg/kg. The interactions between plastic debris concentration and pesticide concentration will be presented, together with the interaction of plastic and pesticides in soil with changes in soil microbial communities, identifying the most sensitive groups which can act as bioindicators for plastic and pesticide pollution in soil.

How to cite: Beriot, N., Zornoza, R., Zomer, P., Ozbolat, O., Lloret, E., Miralles, I., Raúl Ortega, R., Huerta Lwanga, E., and Geissen, V.: Plastic mulch debris in agriculture: accumulation and interactions with pesticides and soil microbiota, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21826, https://doi.org/10.5194/egusphere-egu2020-21826, 2020.

D2437 |
Sascha Oswald, Lena Katharina Schmidt, Eva Bauer, and Christian Tötzke

In recent years we all had to realize that plastics has not only been accumulating in the oceans, but as microplastics also has entered surface waters, soils and partly organisms in large numbers. Thus, as with other pollutants in the environment in the past, we need detection and monitoring methods for quantifying their distribution, fate and pathways. By that we can better understand where they are emitted, where they are present and what are the key mechanisms they undergo. However, this means a new challenge and need for novel approaches because they are different to other pollutants.  In one study we have monitored presence of microplastic particles and some of their properties in a surface water course and groundwater wells close the river banks, detecting them by a novel and fast imaging technique after processing of surface water samples. Furthermore, soil and sand samples from different places were separated by density and then manually analyzed, and the results indicated an extensive presence of microplastic particles. Finally, we have developed a tomography approach to detect microplastic particles also in undisturbed sandy soil or sediment samples. This has the advantage that cores can be taken and analyzed that show the real distribution of microplastic particles, and obtain also some information on their size and shape. Overall, this also can contribute to understand their deposition and displacement in the past. We will demonstrate how a combination of X-ray and neutron tomography could be used to identify microplastic particles non-invasively, for test samples as well as first environmental samples.

How to cite: Oswald, S., Schmidt, L. K., Bauer, E., and Tötzke, C.: Field studies for detecting microplastic in environmental compartments and a novel tomography approach for analysis of undisturbed soil or sediment cores, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22616, https://doi.org/10.5194/egusphere-egu2020-22616, 2020.

D2438 |
Tabea Zeyer and Peter Fiener

There is growing concern regarding the pollution of our environment with plastic materials, whereas especially the dimension of microplastic pollution and its ecological effect is widely discussed. Most studies focus on aquatic environments, while studies in terrestrial systems (mainly soils) are rare. This partly results from the challenges arising when microplastic particles need to be separated from organic and mineral particles. Key analytic techniques for microplastic detection in aquatic and terrestrial systems include Fourier transformation-infrared (FT-IR) and micro-Raman spectroscopy, as well as thermal extraction desorption-gas chromatography-mass spectrometry (TED-GC-MS) and pyrolysis-gas chromatography-mass spectrometry (pyr-GC-MS). While the mass spectrometric methods lack to determine particle sizes, the FT-IR and micro-Raman spectroscopy are very costly and time consuming. Moreover, the latter detection methods are very sensitive to organic matter particles, which are difficult to remove fully during soil sample preparation. Hence, a faster and more robust method to determine microplastic in soils is essential for a wider analysis of this environmental problem. In this study, we combine a density separation scheme with a 3D Laser Scanning Confocal Microscope (Keyence VK-X1000, Japan) analysis to determine the number and size of microplastic particles in soil samples. For the analysis a silty loam (16% sand, 59% silt, 25% clay, 1.3% organic carbon) and a loamy sand (72% sand, 18% silt, 10% clay, 0.9% organic carbon) were spiked with different concentrations of high density Polyethylene (HDPE), low density Polyethylene (LDPE) and Polystyrene (PS) microplastic (HDPE 50 - 100 and 250 - 300 µm, LDPE <50 and 200 - 800 µm, PS <100 µm). 3D Laser Scanning Confocal Microscopy show very promising results while using differences in optical characteristic and especially surface roughness, to distinguish between plastic and mineral as well as organic particles left after density separation. Overall, the 3D Laser Scanning Confocal Microscopy is a promising tool for relatively fast detection and quantification of microplastic in soils, which could perfectly complement the also relative fast mass-spectrometric methods to determine plastic types. However, to result in an operational and automated analyzation process further research based on the 3D Laser Scanning Confocal Microscopy analysis is needed.

How to cite: Zeyer, T. and Fiener, P.: Detection and quantification of microplastic in soils using a 3D Laser Scanning Confocal Microscope, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3612, https://doi.org/10.5194/egusphere-egu2020-3612, 2020.

D2439 |
Nicolas Beriot, Paul Zomer, Raul Zornoza, and Violette Geissen Geissen

In semi-arid regions, the use of plastic mulch and pesticides in conventional agriculture is nearly ubiquitous. The use of plastics and pesticides lead both to the release of residues in the soils. The degradation of plastic and pesticide residues in the soil have been previously studied, but not together despite the fact that pesticides may be sorbed to plastics and that the sorption may change the degradation rate. In fact, the sorption of pesticides on Low Density Polyethylene (LDPE) has been previously  studied, but no data is available for other plastics such as Pro-oxidant Additive Containing (PAC) plastics or “biodegradable” (Bio) plastics. The aim of this research was to measure the sorption pattern of active substances from 38 pesticides on LDPE, PAC and Bio plastic mulches and to compare the decay of the active substances in the presence and absence of plastic debris. For this purpose, 38 active substances from 17 insecticides, 15 fungicides and 6 herbicides commonly applied with plastic mulching in South-east Spain were incubated at 35°C for 15 days with a 3×3 cm² square of plastic mulch (LDPE, PAC and Bio). The QuEChERS (Quick Easy Cheap Effective Rugged Safe) approach was adapted to extract the pesticides. The sorption behaviour depended on both, the pesticide and the plastic mulch type. On average, the sorption percentage was ~23% on LDPE and PAC, and ~50% on Bio. The decay of active substances in the presence of plastic was, on average, 30% lower than the decay of active substances in solution alone. Therefore, efficacy, transport, degradability and/or eco-toxicity of active substances from pesticides may be affected by sorption on plastics. Additionally the sorption of pesticides on plastic debris may affect the plastic degradability due to the toxicity of pesticides to some soil organisms.


How to cite: Beriot, N., Zomer, P., Zornoza, R., and Geissen, V. G.: Interactions between agricultural mulching plastic debris and pesticides , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4614, https://doi.org/10.5194/egusphere-egu2020-4614, 2020.

D2440 |
Collin J. Weber

Today it seems that we are living in the “plastic age”. But plastics as an anthropogenic material element and environmental pollutant has only been in widespread use for about seven decades. The occurrence of both macro- and microplastics in different marine and terrestrial environments provides the possibility to consider plastics as stratigraphic markers. The young age of plastic polymers, the global increase in plastic production since the 1950s and their resistance against environmental degradation, could turn plastics to a useful stratal component. This applies for stratigraphic consideration and also for geoarchaeological issues.

First results from the “Microplastics in floodplain soils” (MiFS) project, investigating the spatial dynamics of microplastic in floodplain soils, allow know a first assessment about the stratigraphic relevance of plastics in alluvial sediments. Alluvial sediments in floodplain areas are known as dynamic chemical and physical sinks as well as spatial transport corridors for sediments and pollutants. Therefore, floodplain soils could also act as an accumulation area for macro- and microplastics.

Four transects in the floodplain cross section distributed in the catchment area of the Lahn river, located in the central German low mountain range, were sampled to a depth of two meters. Samples were dried, sieved and the fractions ˃ 2 mm were analyzed visually using a stereomicroscope and identification criteria. In order to prevent an overestimation, the supposed plastic objects were analyzed using ATR-FTIR spectroscope. The larger microplastic fraction analyzed here seems to be particularly suitable for stratigraphic considerations, since this fraction is less suitable for in-situ displacements by natural processes. The macro- and microplastic data was compared with sediment ages and sedimentation rates from a literature enquiry.

The results of macroplastics (˃ 5 mm) and larger microplastic (˃ 2 mm) contents show that plastic is detectable down to a depth of 70 cm. Common polymer types like PE-LD, PE-HD, PP, PS, PMMA, PVC, PET and others could be identified. At the surface and topsoils, macroplastic accumulations are found on a) river banks (superficial in vegetation or young sandy river bank depositions) and on b) fields under agricultural use. In subsoil samples 75,75 % of identified plastic particles are found in near channel samples located at the river embankment.

Comparing the distribution of macro- and larger microplastics in floodplain soils with sediment ages, sedimentation rates and floodplain morphology, it can be concluded that a deposition of the plastic particles in the natural sedimentation process could only be expected for near channel embankments. In other areas of the floodplain, an in-situ vertical displacement of the plastic particles by tillage or natural processes appears most probable, as the sediments must be significantly older. The application of plastics and especially microplastics as a stratal component in alluvial sediments must therefore be further discussed and investigated.

How to cite: Weber, C. J.: Stratigraphic relevance of macro- and microplastics in alluvial sediments – a first assessment , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4736, https://doi.org/10.5194/egusphere-egu2020-4736, 2020.

D2441 |
Tamara Kukharchyk and Vladimir Chernyuk

In the paper the experience of investigation of polystyrene content in soil and its distribution from industrial enterprise, where expanded polystyrene foam insulation is produced more than 40 years, is presented. Polystyrene belongs to the one of the most widely produced and used polymer. Once being in the environment, this type of plastic breaks easily and crumbles, and is dispersed by wind and water. Moreover, the danger of environmental pollution by polystyrene may be very serious because of hexabromocyclododecane that can be present in polystyrene as flame retardant additive.  Unfortunately, the level of study of environmental pollution with polystyrene and his behavior in soil and water is very poor.

Methodological approaches of sampling and polystyrene identification are shown. Since the enterprise is located on the elevated area close (500-700 m) to a small river with temporary stream, the direct flow of pollutants into the floodplain is possible. Therefore, soil and technogenic deposits at industrial site as well as soil and groundwater within floodplain were collected for study.

In order to identify plastic in solid samples, multiple stages were applied including visual detection, drying, sieving (using mesh widths from 1 to 5 mm), flotation (with heating for the fractions with the size of 1-2 mm and less than 1 mm), and natural organic matter removal. Method of water filtration was used.

Polystyrene was revealed in all solid (12) and liquid (4) samples. High amounts of polystyrene particles with a size less than 5 mm were recorded in technogenic deposits (up to 16700 units/kg) and in soils (up to 1700 units/kg). Particles of microplastic (less than 1 mm) were detected not only in surface layer of soil (0-5 cm) but at the depth of 10-15 cm. Discharges of small granules (less than 1 mm) of raw materials (expanded polystyrene) into environment and its distribution with runoff away from its sources were revealed.

Necessity of further investigation of plastic and microplastic pollution in terrestrial ecosystems in impact zones, including estimates of plastic volume discharges from industrial area with waste, surface runoff and via runoff collector, in order to prevent aquatic ecosystem pollution is discussed.

How to cite: Kukharchyk, T. and Chernyuk, V.: Microplastic of polystyrene in soil and water: fluxes study from industrial site , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4829, https://doi.org/10.5194/egusphere-egu2020-4829, 2020.

D2442 |
Melanie Braun, Aylin Krupp, Rene Heyse, Matthias Mail, and Wulf Amelung

Plastic contamination is a major environmental topic, however, only little knowledge exists about plastic contamination of agroecosystems. Especially the prevalence of plastic in soil and potential entry paths remain largely unknown. Consequently, this study aims at evaluating to what degree compost application is a source of plastic for soil. To do so, we analyzed plastic in 8 different municipal and commercial composts and in topsoil (0-30 cm) of a 12-year compost fertilizer trial with 0, 5, 10 and 20 t compost per hectare. After method testing and adjustment (yielding 76-100% recovery of spiked plastic particles), plastic was analyzed via density separation (ZnCl2) and light microscopy. We found 12±8 to 46±8 plastic items kg-1 compost; concentrations of plastic items > 5 mm were highly variable and ranged between 0.04±0.08 to 1.35±0.53 g kg-1 compost. In contrast to sewage sludge, which contains mostly fibers, in compost particles were dominant. In soil we found 0 to 66±8.5 plastic items kg-1 soil, with highest plastic concentrations in variants with highest compost application, i.e. soils with compost application had 2 to 2.5 higher plastic concentrations than control variants. However, we also could detect additional plastic sources as fields on the border of the trial (near a road) had 3 times higher plastic concentrations than inner fields, leading to a plastic contamination of up to 23 items kg-1. Consequently, we could confirm compost application as an entry path for plastic into soil, leading to a twofold increased plastic contamination of agricultural soil. The determined plastic input via compost might be a minimum estimate since small plastic items like nanoplastics were not included, which warrants further attention.  

How to cite: Braun, M., Krupp, A., Heyse, R., Mail, M., and Amelung, W.: Plastic contamination of soil: is compost the source?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6631, https://doi.org/10.5194/egusphere-egu2020-6631, 2020.

D2443 |
Nils Dietrich, Daniel Wilkinson, Florian Hirsch, Magdalena Sut-Lohmann, Antonia Geschke, and Thomas Raab

Microplastics are not only found in marine and lacustrine environments but also in soils. Microplastics enter natural soil environments from legal or illegal waste deposition. In arable soils, microplastics often stem from the decomposition of plastic sheeting. The accumulation of (micro-)plastic from garbage bags in which biological waste is often disposed, is also a significant problem for the recycling and composting of organic waste. Commercially available compostable bags are advertised as degradable. Thus, these compostable bags ought to accumulate less in soils than non-compostable bags. We present a pilot study to determine the preference of earthworms (Lumbricus terrestris and Eisenia hortensis) for taking up and translocating different types of microplastic in soils. Our initial findings from the soil column experiment suggest that the earthworms show a strong tendency for the uptake of microplastic.  We also observed direct and indirect transport of microplastic by earthworms from the surface to deeper parts of the soil columns.

How to cite: Dietrich, N., Wilkinson, D., Hirsch, F., Sut-Lohmann, M., Geschke, A., and Raab, T.: Microplastics and earthworms in soils: A case study on translocation, toxicity and fate , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7430, https://doi.org/10.5194/egusphere-egu2020-7430, 2020.

D2444 |
Joanna Bullard, Annie Ockelford, Cheryl McKenna Neuman, and Patrick O'Brien

Microplastics have potentially deleterious effects on environments and ecosystems.  The main research focus for translocation of microplastics has been via water, however recent studies of soils in the Alps and Middle East indicate airborne transport following wind erosion may also be significant.  This paper reports wind tunnel studies to determine the extent to which two types of low density microplastic (microbeads and fibres) may be preferentially transported from different substrates – a well-sorted quartz sand and a poorly-sorted soil containing 13% organics.  The polyethylene microbeads had a size range of 212-250 microns and density of 1.2 g cm3.  The polyester fibres were 5000 microns long and 500-1000 microns in width with a density of 1.38 g cm3.  Concentrations of microplastics in the initial wind tunnel bed ranged from 40-1040 mg kg-1 and the wind tunnel was used to determine the wind speeds at which intermittent and continuous saltation occurred using 0.25 m s-1 increments.  Microplastics were entrained for all experiments regardless of the type of microplastic or substrate but the threshold for entrainment was higher for soils (>10.8 m s-1) than for the sand bed (>6.9 m s-1).  The lowest enrichment ratios (ER) for microplastics were associated with the entrainment of beads from the soil bed (ER = 0.5-7) whilst the highest ERs were found for fibres entrained from the soil bed (ER 100 - >1000).  Overall fibres were more likely to be entrained by wind than beads.  The data will subsequently be used to explore the microplastic concentrations and emissions at source required to account for reported microplastic deposition at sink locations.

How to cite: Bullard, J., Ockelford, A., McKenna Neuman, C., and O'Brien, P.: Wind erosion of microplastics from soils: implications for microplastic dispersal and distribution, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7847, https://doi.org/10.5194/egusphere-egu2020-7847, 2020.

D2445 |
Patrizia Hangele, Katharina Luise Müller, Hannes Laermanns, and Christina Bogner

The need to study the occurrence and effects of microplastic (MP) in different ecosystems has become apparent by a variety of studies in the past years. Until recently, research regarding MP in the environment has mainly focused on marine systems. Within terrestrial systems, studies suggest soils to be the biggest sink for MP. Some studies now started to explore the presence of MP in soils. However, there is a substantial lack of the basic mechanistic understanding of the behaviour of MP particles within soils.

This study investigates how the presence of MP in soils affects their hydraulic properties. In order to understand these processes, experiments are set up under controlled laboratory conditions as to set unknown influencing variables to a minimum. Different substrates, from simple sands to undisturbed soils, are investigated in soil cylinders. MP particles of different sizes and forms of the most common plastic types are applied to the surface of the soil cylinders and undergo an irrigation for the MP particles to infiltrate. Soil-water retention curves and soil hydraulic conductivity are measured before and after the application of MP particles. It is hypothesised that the infiltrated MP particles clog a part of the pore space and should thus reduce soil hydraulic conductivity and change the soil-water retention curve of the sample. Knowledge about the influence of MP on soil hydraulic properties are crucial to understand transport and retention of MP in soils.

How to cite: Hangele, P., Müller, K. L., Laermanns, H., and Bogner, C.: The influence of microplastic on soil hydraulic properties, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9337, https://doi.org/10.5194/egusphere-egu2020-9337, 2020.

D2446 |
Marcel Klee, Hannes Laermanns, Katharina Luise Müller, Florian Steininger, and Christina Bogner

The impact of microplastics in different ecosystems has recently become subject of numerous studies. However, the research of the last years has focused mainly on marine ecosystems and neglected terrestrial environments so far. This has led to a substantial lack of knowledge of the transport mechanisms of microplastic in soils and sediments. While first studies in this field investigate the abundance of microplastic in soils, only little is known about surface transport of microplastic particles.

The new approach of time-series analysis acquired by advanced scientific complementary metal–oxide–semiconductor (sCMOS) high-resolution cameras (Hardy et al., 2017, doi:10.1016/ j.catena.2016.11.005) could enhance the understanding of surface transport mechanisms of microplastic. We used a flume-box filled with different materials to trace the movements of fluorescent microplastic particles of 100 µm diameter under artificial irrigation. Furthermore, soil material from the German Wadden Sea was used to trace the run-off transport of microplastic in natural sediments. Here, we present first results on microplastic particle distribution, transport and accumulation as well on macroscopic as on microscopic scales.

How to cite: Klee, M., Laermanns, H., Müller, K. L., Steininger, F., and Bogner, C.: Visualizing transport of microplastic particles on soil surfaces with an advanced-imaging sCMOS camera, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9862, https://doi.org/10.5194/egusphere-egu2020-9862, 2020.

D2447 |
Annie Ockelford, Joanna Bulalrd, Cheryl McKenna-Neuman, and Patrick O'Brien

Recent studies of soils in the Alps and Middle East indicate airborne transport of microplastics following wind erosion may be significant.  Where microplastics have been entrained by wind they show substantial enrichment ratios compared to mineral particle erosion.  Further, microplastic shape affects enrichment ratios with those for fibres greater than for microbeads which may reflect the lower density and asymmetric shape of microplastics compared to soil particles. This suggests that terrestrial to atmospheric transfer of microplastics could be a significant environmental transport pathway. However, currently we have very little understanding of how the properties, in particular the surface characteristics, of the sediment which they are being eroded from affects their entrainment potential.

This paper reports wind tunnel studies run to explore the impacts of soil surface characteristics on microplastic flux by wind erosion.  Experiments were performed in a boundary layer simulation wind tunnel with an open-loop suction design.  The tunnel has a working section of 12.5m x 0.7m x 0.76m and is housed in an environmental chamber which, for this study, was held constant at 20 oC and 20% RH. In experiments two types of low density microplastic (microbeads and fibres) were mixed into a poorly-sorted soil containing 13% organics.  The polyethylene microbeads had a size range of 212-250 microns and density of 1.2 g cm3 and the polyester fibres were 5000 microns long and 500-1000 microns in width with a density of 1.38 g cm3.  Microplastics were mixed into the sediment in concentrations ranging from 40-1040 mg kg-1. For each experiment, test surfaces were prepared by filling a 1.0m x 0.35m x  0.025m metal tray with the given mixture of test material which was lowered into the wind tunnel such that it was flush with the tunnel floor and levelled. The wind tunnel was then switched on and run with increasing wind speeds using 0.25 m s-1 increments until continuous saltation occurred.  Soil surface roughness was scanned prior to and after each experiment using a high resolution laser scanner (0.5mm resolution over the entire test section).  Transported soil and microplastic particles were captured in bulk using a 2 cm wide by 40 cm tall Guelph-Trent wedge trap that was positioned 2 m downwind of the test bed. 

Discussion concentrates on linking the changes in soil surface topography to the magnitude of microplastic flux where data shows that there is a correlation between the development of the soil surfaces and overall microplastic flux.  Specifically, soil surface roughness is seen as a significant control on microplastic flux where it has a greater overall effect on microplastic fibre flux as compared to the microplastic beads.  The outcome of this research is pertinent to developing understanding surrounding the likely controls and hence propensity of microplastics to be entrained from soil by wind erosion.  

How to cite: Ockelford, A., Bulalrd, J., McKenna-Neuman, C., and O'Brien, P.: Wind erosion of microplastics from soils: linking soil surface properties with microplastic flux , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17818, https://doi.org/10.5194/egusphere-egu2020-17818, 2020.

D2448 |
Nina Buenaventura, Sissel Brit Ranneklev, Rachel Hurley, Inger Lise Nerland Bråte, and Christian Vogelsang

The properties of plastic products have become important features in everyday lives, including in Norwegian agriculture. According to Grønn Punkt Norway’s statistics, agriculture is the third largest sector for plastic consumption, after domestic use and industry. Most of the plastic used by agriculture is used for production of round hay bales and as agricultural films to protect and improve crops, known as mulching. The films may be subjected to weathering through mechanical stress, oxidation and photodegradation, leading to fragmentation. These plastic particles can be dispersed into the soil and pass via drainage networks from agricultural soil into local aquatic environments. Additional agricultural plastic sources may come from fertilisers, pesticides, and sewage sludge application to land. This preliminary study investigated soil and runoff-water from agricultural fields in Morsa catchment. Concentrations of plastic (number of plastic particles) and types of plastic were determined in the soil and water samples. The selected sites had berries, grass, and cereal crops. Several fields were selected to represent sludge application: two fields selected had sludge applied recently in 2018, and two had received historical application, 7-8 years ago. In one area, plastic film was used to cover berry crops, for protection and cover. Non-biobased PBAT biodegradable plastic was used as mulching film in one of the vegetable areas. A further type of mulching, which blocks solar insulation to adjust soil temperature and restrict the wavelengths that encourage weed growth, was used in a different vegetable field. One vegetable field that  has not used plastic products (including sludge application) in the past and was considered as a reference field in this study.


Globally, there are only a few studies that have measured microplastics in agricultural soils, and none in Norway to date. The concentrations of plastics above 50 µm found in the samples from Morsa were low, except from were mulching occurred with the plastic film PBAT. Microplastic PBAT concentrations were considered to be high, and the soil contamination was comparable with other values reported for soil undergoing intense agricultural production in other parts of the world.  In runoff-water from a field where cereals and grass were grown, the concentrations of microplastics were considered high compared to other reported values from freshwater systems. This indicates that plastics can be mobilised from agricultural soils to the aquatic environment, and films from agricultural use may represent an important source. Polyethylene fragments were the dominant particle type found in the runoff-water, which may have originated from the soil as they represent the most dominant particle type in the corresponding field. A total of 14 different plastic polymer types were found in the soil samples, but, there was little agreement between the use of plastics (e.g. agricultural film) and what type was found in the soil. Samples from areas where neither sludge nor film was used also contained microplastics. The overall dominant particle morphologies were fragments, fibres and films. These data represent the first baseline assessment of microplastic contamination in agricultural soils undergoing a range of different plastic application types in Norway.

How to cite: Buenaventura, N., Ranneklev, S. B., Hurley, R., Nerland Bråte, I. L., and Vogelsang, C.: Plastics in Agriculture: Sources, mass balance and transport to local aquatic environments , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18272, https://doi.org/10.5194/egusphere-egu2020-18272, 2020.

D2449 |
Corinna Földi

Fast and reliable quantification of microplastics in environmental samples is currently a challenging task. To enable monitoring of microplastics, a fast and robust method in sample preparation and subsequent analysis is of extraordinary need and urgency. Therefore, the combination of pressurized liquid extraction and Pyr-GC/MS has been developed. The fully automated extraction includes a pre-extraction via methanol for matrix elimination and a subsequent main extraction for microplastics using tetrahydrofuran to enrich microplastics on silica gel which is hence analyzed by means of Pyr-GC/MS.

Several commonly occurring organic matrices known to result in GC interferences were tested to be eliminated by pressurized liquid extraction.  For the most frequently used synthetic polymers PE, PP, and PS extraction efficiencies of 113-131, 80-98, and 70-118 %, respectively, and limits of quantification down to 0.005 mg/g were achieved.

The developed method was validated and applied to environmental samples with complex matrices such as roadside soils, potting soils, and sewage sludge. In all these matrices PE, PP, and PS were detected with contents ranging from 0.8 to 3.3, 0.01 to 0.36, and 0.06 to 0.61 mg/g. However, calcined sea sand spiked with wood, leaves, and humic acids, respectively, were found to interfere with PE quantification (0.140, 0.210, and 0.050 mg/g). Reduction of these interferences will be further evaluated.

How to cite: Földi, C.: Quantification of Microplastics in environmental samples using pressurized liquid extraction and Pyr-GC/MS, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19200, https://doi.org/10.5194/egusphere-egu2020-19200, 2020.

D2450 |
Yosri-Kamal Wiesner, Axel Müller, Claus Gerhard Bannick, Marius Bednarz, and Ulrike Braun

The ubiquitous presence of unintended plastics in the environment has been an issue in scientific studies and public debate in the last years. It is well known that oxidative degradation and subsequent fragmentation, caused by UV-radiation, aging and abrasion lead to the decomposition of larger plastic products into microplastics (MP). Possible effects of these MP on ecosystems are still unclear. Recent studies on MP findings are focused mainly on aquatic systems, while little is known about MP in terrestrial ecosystems. Fermentation residues, sewage sludge and compost represent an input path of plastics in soils through targeted application in agriculture. For this reason, analysis of the total content of plastic in organic fertilizers as a sink and source of MP in ecosystems is of high interest.

In 2017, approximately 14.2 million tons of biodegradable waste were collected, from which 3.9 million tons of compost was produced. Improper waste separation result in plastic fragments in the biowaste, some of which end up in the compost and might be degrade to MP. In Germany, compost is used as fertilizer in agriculture and landscape design, hence MP could enter the soil by this pathway. Spectroscopic methods such as Raman or FTIR are not suitable for determining the mass content of microplastic, as these output a particle number.

Therefore, we show the application of ThermoExtractionDesorption-GasChromatography-MassSpectrometry (TED-GC-MS) as a fast, integral analytical technique, which in contrast to the spectroscopic methods does not measure the number of particles but a mass content. The sample is pyrolyzed to 600°C in a nitrogen atmosphere and an excerpt of the pyrolysis gases is collected on a solid phase adsorber. Afterwards, the decomposition gases are desorbed and measured in a GC-MS system. Characteristic pyrolysis products of each polymer can be used to identify the polymer type and determine the mass contents in the present sample. This method is well established for the analysis of MP in water filtrate samples. Here, we will first demonstrate the use of TED-GC-MS for compost.

This current study will also give inside in various important aspects of sample preparation, which include a meaningful size fractionation, a necessary density separation regarding the removal of inorganic contents and at finally a homogenization.

How to cite: Wiesner, Y.-K., Müller, A., Bannick, C. G., Bednarz, M., and Braun, U.: Pathways of microplastics in soils - Detection of microplastic contents in compost using a thermal decomposition method, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22456, https://doi.org/10.5194/egusphere-egu2020-22456, 2020.

D2451 |
Marius Bednarz, Nathan Obermaier, and Claus Gerhard Bannick

Plastics are found ubiquitously in all environmental media. Evidence of microplastic occurrence was also provided for various biota. At the beginning of the scientific debate, the oceans as final plastics sinks were in the foreground, whereas current research work focuses on the sources of input, including
surface waters. The water content of these surface waters are influenced by urban and rural areas, including the adjoining soils.
Like oceans, soils are a final sink for many substances, including plastics. Sources of plastics are diverse and depend on use and management. With respect to analytics, soil material is much more complex than suspended solids in water. Therefore the type of soil, grain size, the organic content as well as containing metal ions are important parameters.
For the detection of plastics, there are different analytical methods. Spectroscopic methods determine the particle numbers, sizes, and shapes. Pyrolytic methods return the total contents of plastics within the sample. These include the Thermo-Extraction-Desorption-Gas-Chromatography-MassSpectrometry (TED-GC-MS).
In many environmental samples, there are substances that interfere with both the sample detection and sample preparation. Thus, mineral components must be removed in order to be able to grind better. For their removal, density separation is suitable. In this article, experiments with density separation will be presented.
There are different options to prepare solid samples with density separation, including major methodological differences in the selection of the separation solution and the phase separation.
Various plastic spiked solid samples (terrestrial and sub hydric soils) were biologized. Subsequently, recovery tests were carried out using a density separation method with different separation solutions.
Ultrasound was used to destroy soil agglomerates and release occluded plastics. The separated floated material was sucked off through a 6 μm stainless steel filter. The plastic content in the rinsed organic material was quantified with a TED-GC-MS analysis.
The presented method shows medium (PE: 47 – 82 %) to high (PS: 89 – 100 %) recovery rates depending on the separation solution used and the environmental sample examined.

How to cite: Bednarz, M., Obermaier, N., and Bannick, C. G.: Density separation of soils as sample preparation for the determination of plastics, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22555, https://doi.org/10.5194/egusphere-egu2020-22555, 2020.

D2452 |
Gerasimos Gkoutselis and Gerhard Rambold

The plastic waste input into terrestrial ecosystems is a serious and ongoing problem, particularly in developing countries due to deficient or non-existent recycling management. A so-called 'plastic ban' has been proclaimed in Kenya in 2017. Despite the ban, waste of all kinds of plastics, mainly polyethylene (PE) still exists at large amounts, particularly in the municipal environment of the country, where plastic solid waste (PSW) permeates the upper layers of the soil. Microorganisms are the key players in the decomposition of (polymeric) materials. Landfills (dumpsites) are designated hot spots of environmental pollution with plastics. Therefore, landfills and plastic-contaminated sites in the town of Siaya (Western Kenya) are considered suitable locations to discover with a high probability so-called soil-borne, 'plasticophilic' microorganisms. Since microfungal diversity in these regions is virtually unknown, a high-throughput method was applied to obtain a first overview on potential fungal plastic degraders and the composition of their respective communities. The focus of the screening was laid on the distinction between directly plastic-associated and generally soil-dwelling fungi. In other words, it was the aim to characterise via community barcoding associations of specifically plastic-colonizing species or OTUs in comparative analyses of both substrates, i.e. bulk soil and (macro)plastic. Ultimately, the aim of this study was to identify those 'key species' that contribute most to β̞-diversity, by far-reaching adaptations to this anthropogenic trophic niche. Eventually, this investigation marks an initiation point to a comprehensive screening in equatorial Africa for the isolation of fungi capable of plastic biodegradation.

How to cite: Gkoutselis, G. and Rambold, G.: Microbial life on waste: fungal communities on plastic debris from dumpsites in East Africa, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22624, https://doi.org/10.5194/egusphere-egu2020-22624, 2020.