HS8.1.4

Microplastic pollution of the terrestrial environment and its potential impact on ecosystem services are gaining increasing public and scientific attention. Although the number of investigations on microplastic presence in soil under different management systems is growing, knowledge on the potential mobility of microplastics and their spatial distribution within soil is still lacking. In particular, microplastic fibres are often considered less mobile in soil due to their elongated shape and the resulting potential entanglement in pore structures or aggregated soil particles. While these processes may affect their water-driven transport, biologically-driven transport may still occur unimpeded because particles may be ingested by macrofauna such as earthworms. Micro- and nanoplastic transport by earthworms has been previously observed, however, the effect of particle shape on the transport dynamics is still elusive.

For understanding microplastic fibre transport in soil from a mechanistic perspective, we performed a series of process-studies with deep-burrowing earthworms, i.e. Lumbricus terrestris, in microcosms. We utilized metal-doped fibrous polyethylene terephthalate (PET) microplastics (1.27±0.66 mm) for a facilitated detection through acid extraction and subsequent analysis via inductively-coupled plasma mass-spectrometry. Fibres were spiked into the top of the soil columns of the microcosms, which were sampled according to specific depth segments every 7 days for four weeks. As a result, we were able to quantify fibre transport in soil profiles with a temporal resolution. Earthworms were important drivers of vertical transport of microplastic fibres in the soil, with fibres visibly incorporated into burrow walls. Thus, despite their elongated shape and relative larger size, microplastic fibres are not necessarily immobilized by interactions with soil particles, but continuously affected by burrowing soil organisms. Understanding these transport dynamics and the potential spatial distribution of microplastics of different shapes and sizes in the field is crucial in order to support appropriate sampling schemes for monitoring and for obtaining accurate mass estimates of microplastic pollution of terrestrial ecosystems.

How to cite: Heinze, W. M., Mitrano, D. M., and Cornelis, G.: Bioturbation-driven transport of microplastic fibres in soil, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7987, https://doi.org/10.5194/egusphere-egu22-7987, 2022.

Global plastic production reached 368 million tonnes in 2019 (Plastics Europe, 2020), with the greatest demand being for packaging. Plastic waste management in many countries is mismanaged, with ~25% of post-consumer waste globally sent to landfill in 2018, this increases the likelihood of plastic ending up in the environment, raising concerns about the impact of plastic pollution on the environment. Microplastics (particles <5mm) are emerging contaminants with high risk due to their ubiquity in the environment and the as yet unknown scale of their impact on organisms and ecosystems.

Microplastics are present in all environmental compartments, but research to date has focused on marine systems, leaving a substantial knowledge gap in understanding how microplastics behave in and impact other environments, especially terrestrial ones. Terrestrial soils provide key ecosystem services (e.g. food provision and climate regulation), however these services are threatened by soil pollution including from microplastics. Soils act as a sink for microplastics, which typically enter the soil through their widespread use in agriculture. Common entry pathways include the application of microplastic containing sewage sludge as fertiliser, and the direct application of microplastics via the polymer encapsulation of pesticides and seeds. Whilst the impacts of microplastics are not fully known, it is possible that they will compromise soil health and functions.

We urgently need to understand how microplastics of different compositions and sources affect soil ecosystems, but research progress is hindered due to the lack of standardised protocols for the identification, extraction, and analysis of microplastics in the complex soil environment. Soil is high in organic matter, meaning protocols devised for aquatic samples are not feasible because more aggressive digestion steps are required to remove soil organics.

This poster looks at the extraction and analysis of microplastics from soil samples, following a generalised framework of sieving, density separation, organic digestion, and analysis. It outlines the effectiveness of each step in the soil matrix and its applicability for both biodegradable and non-biodegradable microplastics. It compares the effect of commonly used digestion solutions (e.g. Fenton’s reagent, hydrogen peroxide) on the polymers, by using Raman spectroscopy to characterise the plastics before and after treatment, and thus to assess chemical changes arising from the sample processing. Based on these results an optimal workflow is defined as the basis for evaluating the biodegradation of microplastics in soil.

How to cite: Davies, G., Lynch, I., Krause, S., Marshall, S., and Mascelloni, M.: Improving analytical methods for the extraction and analysis of biodegradable and non-biodegradable microplastics in the soil environment., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-207, https://doi.org/10.5194/egusphere-egu22-207, 2022.

There is an expected increase of microplastics (MPs) concentrations in terrestrial ecosystems in the next decades from a variety of sources. Understanding the responses of soil ecosystems to the presence of MPs becomes increasingly important as multiple stressors can act together to negatively impact this environmental compartment, especially in the context of global warming. It has already been shown that MPs (particularly fibers) can influence several parameters of soil structure and function, including aggregate formation, water holding capacity and microbial activity. Furthermore, recent studies suggest that the presence of MPs in soils affects the emissions of the greenhouse gases (GHG) carbon dioxide (CO₂) and nitrous oxide (N₂O). The mechanisms underpinning the direction and magnitude of MPs effects on GHG emissions from soils are uncertain, mainly due to the lack of knowledge of how the presence of MPs drives changes in soil structure and the subsequent link between soil structure and microbial activity. Here, we hypothesized that the presence of MPs affects soil structure by increasing porosity, leading to higher O₂ availability and consequently higher decomposition of soil organic matter (SOM) and lower denitrification activity. In this study, we spiked MPs of different polymers (PET, PLA), morphologies (fragments, fibers) and sizes to a custom built rhizotron (7 x 4 x 1 cm) filled will a clay soil with a MP treatment of 5 w/w%. The soil was initially sterilized, but we added microbial inoculum collected from the same soil and glucose (as a substrate source) in known concentrations to assess soil respiration over time. We determined the spatial distribution of microbial respiration by mapping O₂ concentrations using optode imaging, with a resolution of 1 image every 10 minutes over the course of 48 hours. Soil pore size, pore distribution and the pore connectivity network were determined by using X-ray micro-tomography (µCT). GHG emissions were measured by placing replicate set-ups in a Tedlar bag and collecting CO₂ and N₂O from the headspace in exetainers to be analyzed by gas chromatography. This approach allowed us to collect real-time O₂ distribution and compare this to X-ray micro-tomography (µCT) data from the same soil matrix to assess MPs impacts to the soil structure and link it to GHG emissions compared to the control (i.e. no MPs addition). Collectively, in this presentation we will discuss the impacts of MPs addition to soil and on the linkages between soil structure, microbial activity and GHG emissions. This study can serve as a baseline for understanding the important impacts of MPs to soil functioning, which is particularly relevant as plastics are increasingly used directly in agriculture and can have direct releases to the terrestrial ecosystem.

How to cite: Nunez, J., Jimenez-Martinez, J., and Mitrano, D.: Disentangling microplastics effects on soil structure, microbial activity and greenhouse gas emissions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2723, https://doi.org/10.5194/egusphere-egu22-2723, 2022.

Microplastics pose a threat to all the environmental compartments and specifically to aquatic ecosystems. Lakes are particularly exposed to it as they act as accumulator of pollution from their watersheds. Unfortunately, the fate of microplastics in lake ecosystems remains poorly understood because of the multiplicity of sources and transfer pathways. For the first time, the Plastilac project focuses on the contamination of high altitude lakes (from 1300 m to 2800 m above the sea level) by microplastics. Remote lakes constitute easier-to-investigate ecosystems because there are fewer potential sources of microplastics in their watershed, namely the atmospheric deposit, the supply from the watershed through the tributaries and the tourist attendance. Thus, both water column and sediment from 10 lakes located across the French Alps were sampled. The results showed that no lake was free from microplastics, proving the ubiquity of this pollution at a regional scale. The abundance of microplastics varied significantly from one lake to another and the concentrations measured in high altitude lakes (around 10 MP.m^-3) were approximately 100 times lower than those reported in the literature for lowland lakes. The water column contamination was not correlated to the vicinity of potential sources (urban areas). On the contrary, higher sediment contaminations were observed in lakes located nearby urban areas. Our analyses also showed that the residence times of microplastics in the water column of these lakes were relatively short, of the order of a few days. In contrast, the residence times of microplastics in the sediments were much longer and lake bottoms retain traces of past contamination. This work constitutes a first for understanding the fate of microplastics in mountainous environments. It provides important information on their dynamics and, in particular, on the temporal dimension of this pollution.

How to cite: Gateuille, D., Dusaucy, J., Naffrechoux, E., Fanget, P., Tourreau, G., Gallinelli, P., and Gillet, F.: Microplastic mass balances in remote alpine lakes, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3497, https://doi.org/10.5194/egusphere-egu22-3497, 2022.

Visible flow chamber systems packed with porous media (at both macroscale and pore scale) and packed column systems for the first time were used to systematically investigated the impacts of seawater intrusion and groundwater-seawater displacement on the transport behaviors of marine plastic particles with different sizes in porous media. We found that seawater intrusion could transfer all three sized plastics into coastal porous media and their transport would be affected by seawater flow velocity. For example, 8.5%, 24.8%, 39.8% of 1 mm plastic particles could pass through the columns during the 10, 50 and 250 m/d seawater intrusion processes, respectively. The groundwater-seawater displacement process could re-mobilize plastic particles pre-attached onto sand. The percentages of released plastic particles were negatively correlated with the sizes of plastic particles and the ionic strength of displacement groundwater. Groundwater velocity did not obviously affect the release of plastic particles from sand. The percentage of released plastic particles were affected by seawater intrusion cycles. XDLVO was employed to theoretically explain the transport behaviors of plastic particles under different conditions. Our study showed that seawater intrusion would transfer marine plastic particles into coastal aquifer and groundwater-seawater displacement could affect the release of plastic particles from porous media.

How to cite: li, M. and tong, M.: Transport and deposition of plastic particles in porous media during seawater intrusion and groundwater-seawater displacement processes, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3489, https://doi.org/10.5194/egusphere-egu22-3489, 2022.

Although the occurrence of microplastic particles (MPs) and their impact on different environments have become a widely recognized research topics, their transport mechanisms in terrestrial environments are still understudied. While first research in this field have focused on the abundance of MPs in soils and its vertical distribution, only little is known about the mechanisms of MP transport on sediment and soils surfaces. This might be explained by the challenges of detecting MPs in terrestrial settings.

Therefore, we investigate the surface transport mechanisms and patterns by using fluorescent MP particles that can be tracked by an advanced complementary metal–oxide–semiconductor (CMOS) high-resolution camera. Within this study we used an experimental set-up including a flume box with surfaces of different roughness and several rates of surface discharge. We traced the pathways of environmentally pristine and biofouled fluorescent amorphously shaped Polystyrene (PS) and Polymethyl methacrylate (PMMA) to analyze how polymer type, biofilm, surface roughness and film thickness influence their transport. Subsequently, time series analysis of the images were performed and evaluated using R software. This included the calculation of particle size, estimation of pathways and path lengths. First results suggest a large influence of the water film thickness of the runoff and the surface roughness. 

How to cite: Laermanns, H., Haas, D., Rolf, M., Steininger, F., Löder, M., and Bogner, C.: Comparing the transport of pristine and biofouled microplastic particles on rough surfaces, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7055, https://doi.org/10.5194/egusphere-egu22-7055, 2022.

Microplastics are ubiquitous in the terrestrial environment and have also been detected in soils. However, how microplastics are transported vertically in the soil is still a matter of research. Especially, the influence of precipitation, preferential pathways and bioturbation on the vertical translocation of microplastics is still unclear. One cause is the time-consuming microplastic analysis in soils that requires substantial sample pretreatment. Additionally, we are still lacking a standard protocol to quantify and qualify microplastic particles in environmental samples.

Therefore, in this study, we present a method for irrigation experiments with soil column to study the vertical transport of microplastics. In the upper 2 cm of the column, fluorescent microplastics are added. We spike the irrigation water with deuterium oxide to trace the breakthrough of the water during the irrigation experiment. After the irrigation experiment, the soil column is frozen and subsequently cut in 2 cm slices and photographed under UV illumination. Then, we process the images by the software MP-VAT to analyse the distribution of the MP particles within the slices and within the soil column.

How to cite: Bogner, C., Rolf, M., and Laermanns, H.: Visualization of fluorescent microplastics in soil column experiments in different depths, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9811, https://doi.org/10.5194/egusphere-egu22-9811, 2022.

Pathways of Microplastic (MP) into ecosystems are manifold and range from agricultural mulching practices to atmospheric deposition with soil being considered the largest sink of MP in terrestrial ecosystems. Once deposited there, MP is posing a hydrophobic surface addition. Former experiments showed that pristine MP can cause lower water saturation of pore spaces and so change the liquid configuration within a porous network. If water cannot reach MP, biotic degradation might be hindered. However, in natural soil systems MP can be coated over time by soil abundant substances e.g., iron compounds with the potential effect of decreasing their hydrophobicity. We hypothesize that: 1) ferrihydrite pre-coated MP shows reduced hydrophobicity; 2) in-situ wetting and drying cycles with ferrihydrite leads to partial coating of MP.

We tested these hypotheses by applying hotspots of MP, pre-coated and pristine, to sand in rectangular columns and performed neutron imaging during capillary rise. Neutron imaging allowed for visualizing and quantifying liquid dynamics and configuration. Water was used for the pre-coated MP (n=6) variants and ferrihydrite suspension (100 mg L^-1) in three wetting and drying cycles for the pristine MP (n=6) variants. The utilized MP are polystyrene (PS, 20-75 µm) and polyethylene terephthalate (PET, 20-75 µm). The grain size of sand was 0.7-1.2 mm. Pre-coating was achieved by shaking the raw material for 3 h in a 100 mg L^-1 ferrihydrite suspension and subsequent drying in a sieve supported by a vacuum pump.

Capillary rise of water into pristine MP variants exhibited zero water saturation at the hotspot and water movement around the MP aggregation was observed. Capillary rise of water into pre-coated MP variants differ in result by polymer type. While pre-coated PS is still hydrophobic, the pore space of pre-coated PET was completely water saturated. The rising water accelerated towards the hotspot due to its lower matric potential compared to sand.

Capillary rise of ferrihydrite suspension in wetting and drying cycles also showed varying results according to polymer type. While there is no effect on water saturation on PS in the hotspot after three wetting cycles, PET exhibits a slightly higher water saturation during the second wetting but stagnating in the third.

Our results suggest that ferrihydrite coating, being only one of numerous potential coating agents, can bond to MP and change its surface polarity. Differences in completeness of coating can be explained by inherent chemical and physical properties of different polymer types. But once hydrophilic, completely, or only part of the surface, water flow induced colonization and migration of microorganisms and their enzymes can proceed and biotic degradation can take place. The open question lies within the time frame necessary to overcome MP’s inherent hydrophobicity.

How to cite: Cramer, A., Schmidtmann, J., Kaestner, A., and Carminati, A.: Microplastic water repellency reduced by ferrihydrite coating, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12462, https://doi.org/10.5194/egusphere-egu22-12462, 2022.

The increasing amount of microplastics (hereafter MPs) in freshwater ecosystems appears as a highly relevant environmental issue as MPs represent a group of contaminants of emerging concern responsible for water pollution worldwide. Within MPs are included particles with the potential to enter the environment, persist in it and be easily ingested by aquatic organisms with important adverse effects on both the ecosystems and human health. Research has revealed that the presence of MPs in organisms can cause negative effects and the risk associated with their long-term exposure is still under debate. Within freshwater ecosystems, streams and rivers represent one of the most important delivery vectors responsible for the transfer of MPs from terrestrial to marine environments. Therefore, understanding their transport dynamics became crucial to propose mitigation strategies and to manage and possibly reduce adverse health effects. Here, we present a simple model able to predict the fate of MPs along the different reaches that compose a river network. The model solves the general advection-dispersion-reaction equation (ADRE) along each reach of the river network considering the release of MPs from the Waste Water Treatment Plants (WWTPs). Using a combination of free access databases (MERIT, ReachHydro) and computational algorithms we estimate MPs concentrations at different locations in the river network. The model capability to capture MPs transport was tested by using available literature data where MPs samples were collected upstream and downstream of WWTPs. Our proposed method was able to satisfactorily reproduce the measured values proving a useful tool to understand the role of river networks in controlling the fate of MPs and to provide the basis for introducing suitable mitigation strategies.

How to cite: Portillo De Arbeloa, N., Marzadri, A., and Bellin, A.: On modeling the fate of microplastics along river networks, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11802, https://doi.org/10.5194/egusphere-egu22-11802, 2022.

Due to the interaction of fertilizers with microplastics (MPs) and porous media, fertilization process would influence MPs transport and distributions in soil. The co-impacts of N fertilizers (both inorganic and organic N fertilizers) and humic substance on MPs transport/retention behaviors in porous media were examined in 10mM KCl solutions at pH 6. NH₄Cl and CO(NH₂)₂ were employed as inorganic and organic N fertilizers, respectively, while humic acid (HA) was used as model humic substance. We found that for all three sized MPs (0.2, 1 and 2 μm) without HA, both types of N fertilizers decreased their transport/increased their retention in porous media (both quartz sand and soil). N fertilizers adsorbed onto surfaces of MPs and sand/soil, lowering the electrostatic repulsion between MPs and porous media, thus contributed to the enhanced MPs deposition. MPs with N fertilizers in solutions more tightly attached onto porous media and thus were more difficult to be re-mobilized by low ionic strength solution elution. Via steric repulsion and increasing electrostatic repulsion between MPs and porous media due to adsorption onto their surfaces, HA could increase MPs transport with N fertilizers in solutions.

How to cite: Rong, H. and Tong, M.: Transport and deposition behaviors of microplastics in porous media: Co-impacts of N fertilizers and humic acid., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3664, https://doi.org/10.5194/egusphere-egu22-3664, 2022.

It has been established that various anthropogenic contaminants have already reached all the world’s pristine locations, including the polar regions. While some of those contaminants, such as lead and soot, are decreasing in the environment, thanks to international regulations, other novel contaminants emerge. Plastic pollution has been shown as a durable novel pollutant, and, since recently, smaller and smaller plastics particles have been identified in various environments (air, water and soil). Considerable research already exists measuring the plastics in the 5 mm to micrometre size range (microplastics). However, far less is known about the plastics debris that fragmented to the sub-micrometre size (nanoplastics). As these small particles are light, it is expected that they have already reached the most remote places on Earth, e.g. transported across the globe by air movement. In this work, we used a novel method based on Thermal Desorption – Proton Transfer Reaction – Mass Spectrometry (TD-PTR-MS) to detect and measure nanoplastics of different types in the water sampled from a Greenland firn core (T2015-A5) and a sea ice core from Antarctica. We identify polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS), polyvinyl chloride (PVC), and Tire wear nanoparticles in the 14 m deep Greenland firn core and PE, PP and PET in sea ice from Antarctica. Nanoplastics mass concentrations were on average 13.2 ng/mL for Greenland firn samples and 52.3 ng/mL for Antarctic sea ice. We further discuss the possible sources of nanoplastics that we found at these remote locations, which likely involve complex processes of plastic circulation (emission from both land and sea surface, atmospheric and marine circulation).

How to cite: Materić, D., Kjær, H. A., Vallelonga, P., Tison, J.-L., Röckmann, T., and Holzinger, R.: Nanoplastics measurements in Northern and Southern Polar Ice, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5082, https://doi.org/10.5194/egusphere-egu22-5082, 2022.

Thermal Desorption – Proton Transfer Reaction – Mass Spectrometry (TD-PTR-MS) is a sensitive method capable of measuring nanoplastics in environmental samples. The method works on the principle that different types of plastic have different melting points (also different from many organics in the matrix), and they release rich (semi)volatile organic compounds signal (smells) when heated up. A gradual increase of the sample temperature combined with real-time, quantitative mass spectrometry (PTR-MS) allowed us to selectively measure the type and concentration of the nanoplastics. Data processing involves multiple ions associated with thermal degradation products of plastics, which ensures selectivity in identifying different plastic types.

However, the method is procedural and challenging. The sampling practice, sample treatment, instrument's operational settings, and data processing can result in large uncertainties, which need to be addressed in each experiment. Here we discuss these analytical challenges in the context of complex environmental nanoplastic measurement and provide recommendations for good experimental practice and robust quality control.

How to cite: Materić, D., Notø, H. Ø., Mosselmans, S., and Holzinger, R.: TD-PTR-MS for nanoplastics research – high sensitivity and big challenges, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12098, https://doi.org/10.5194/egusphere-egu22-12098, 2022.

Metal nanoparticles constitute promising, eco-compatible alternatives to be used as nano-fertilizers or nano-fungicides although their potential impact on the agroecosystem is poorly studied. In the present study, the impact of copper (Cu-NPs, CuO-NPs), silver (Ag-NPs) and zinc oxide (ZnO-NPs) nanoparticles (NPs) on tomato plant development, physiological properties and the symbiotic relationship with the endophytic Fusarium solani FsK strain was assessed in comparison with their respective bulk/ionic counterparts. Both NPs and their counterparts did not affect the number of germinated tomato seeds even at higher concentrations except for AgNO₃, which significantly decreased seed germination rates. On the contrary, a dose dependent decrease of root length was observed in most NP/bulk treatment cases. This was also the case for dry weight of tomato plants which was also significantly reduced upon treatment with NPs and counterparts especially in the cases of AgNO₃, Cu-NPs, ZnO-NPs, and ZnSO₄. Although differences between NPs and bulk counterparts varied, root and shoot length of grown tomato plants was also negatively affected by treatments. NPs/bulk counterpart treatments resulted in a marked oxidative stress response as indicated by increased MDA and H₂O₂ levels of treated plants. Photosynthetic pigments were also significantly affected by NP/bulk treatments, a fact evident from the reduced chlorophyl-a and carotenoid levels recorded. The FsK tomato-symbiotic strain was significantly more sensitive to Cu-NPs and ZnO-NPs than CuO-NPs and Ag-NPs as revealed in both mycelial growth and spore germination fungitoxicity tests. With the exception of AgNO₃,which was 8 to 9-fold more toxic than Ag-NPs, all NPs were more fungitoxic to FsK than their bulk/ionic counterparts. FsK colonization of roots was not significantly affected by treatments with NPs and counterparts indicating that, once established inside the roots, the endophyte is shielded against the toxic effect of metals. At the same time, an alleviation of CuO-NPs, ZnO-NPs,and ZnSO₄ phytoxicity was observed when FsK was present inside tomato roots in terms of plant dry weight. Concluding, results suggest that phytotoxicity of NPs in tomato treated plants should be considered before nano-fertilizer/fungicide treatments while the benefits of FsK inoculation of tomato plants may extent to resistance towards these toxic agents for both organisms.

How to cite: Chrysikopoulos, C. V., Malandrakis, A. A., Kavroulakis, N., Avramidou, M., Papadopoulou, K. K., and Tsaniklidis, G.: Impact of metal nanoparticles on tomato growth, physiology and symbiosis with the Fusarium solani FsK strain, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1744, https://doi.org/10.5194/egusphere-egu22-1744, 2022.

How to cite: Perez, L. J., Plymale, A., and Parashar, R.: Bacterial motility dynamics in open and confined porous media, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1561, https://doi.org/10.5194/egusphere-egu22-1561, 2022.

Bacterial removal by sand filtration system is commonly inefficient due to the low bacterial adsorption capacity of sand. To improve the bacterial removal performance, biochar fabricated at different temperatures (400 °C, 550 °C and 700 °C) and arginine modified biochar were added into sand filtration columns as filter layers (0.5 and 1 wt%). Addition of biochar into sand columns could improve the removal efficiency for both Escherichia coli and Bacillus subtilis under both slow (4 m/day) and fast (240 m/day) filtration conditions. Bacterial removal efficiency in sand columns with the addition of biochar fabricated at 700 °C were higher than those fabricated at 400 °C and 550 °C due to its best bacterial adsorption capacity. Modification of biochar with arginine could further improve the bacterial removal performance. Specifically, complete bacterial removal (1.35×10⁷ ± 10% cells/mL) could be achieved under both slow and fast filtration conditions in sand columns with 1 wt% arginine functionalized biochar amendment. The enhanced bacterial adsorption capacity mainly contributed to the increased bacterial capture performance in columns with addition of arginine-modified biochar. Bacteria more tightly bounded with arginine-modified biochar than bulk biochar. Moreover, complete bacterial removal with the copresence of 5 mg/L humic acid in suspensions was acquired in columns with addition of 1 wt% arginine-modified biochar. Efficient bacterial removal in actual river water, multiple filtration cycles as well as longtime injection duration (100 pore volumes injection) was also obtained. The results of this study demonstrated that arginine-modified biochar had great potential to treat water contaminated by pathogenic bacteria.

How to cite: Mengya, Z. and Tong, M.: Improved removal performance of Gram-negative and Gram-positive bacteria in sand filtration system with arginine modified biochar amendment, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3505, https://doi.org/10.5194/egusphere-egu22-3505, 2022.

 Amoebas are protists that are widespread in water and soil environments. Some species are pathogenic, inducing potentially lethal effects on humans, making them a major threat to public health. Nonpathogenic amoebas are also of concern because they have the potential to carry a mini-microbiome of bacteria, either transiently or via more long-term stable transport. Due to their resistance to disinfection processes, the physical removal of amoeba by filtration is necessary to prevent their propagation throughout drinking water distribution networks and occurrence in tap water. In this study, a model amoeba species Dictyostelium discoideum was used to study the transport and retention behavior of amoeba spores in porous media. The key factors affecting the transport behavior of amoeba spores in fully saturated media were comprehensively evaluated, with experiments performed using a quartz crystal microbalance with dissipation monitoring (QCM-D) and parallel plate chamber system. The effects of ionic strength (IS) on the deposition of spores were found to be in contrast to the predicted Derjaguin-Landau-Verwey-Overbeek (DLVO) theory that more deposition is observed under lower-IS conditions. The presence of extracellular polymeric substances (EPS) was found to be the main contributor to deposition behavior. Overall, these results provide plausible evidence for the presence of amoeba in tap water. Furthermore, this is one of the first studies to examine the mechanisms affecting the fate of amoeba spores in porous media, providing a significant baseline for future research to minimize the safety risk presented by amoeba in porous media.

How to cite: Jin, C.: Transport and Retention of Free-Living Amoeba Spores in PorousMedia, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3893, https://doi.org/10.5194/egusphere-egu22-3893, 2022.

This work focuses on the development of a mechanistic Fe(hydr)oxide based (HFO) colloid-facilitated reactive transport model which identifies the impact of HFO colloids on the stability and mobility of heavy metals (Zn and Pb) in example subsurface benthic sediments of Lake Coeur d’Alene (LCdA), USA. Ferrihydrite colloids are considered as the major sorbing phases for heavy metals, where the metal adsorption is implemented by surface complexation using double layer modeling and with electrostatic double layer (EDL) implementation using the dual-domain diffusive mass transfer characteristics of the PHREEQC code. The transport of colloidal phases is implemented by using 4 different advective velocities of the solution and colloidal particles (3 x 10^-8 cm/s, 3 x 10^-7 cm/s, 9 x 10^-7 cm/s, and 3 x 10^-6 cm/s), which are within the range reported in the literature for similar porous systems with relevant ranges of Peclet numbers. The advective transport simulation results are also compared with pure diffusive transport of solutes (and HFO) in the system, where the effective diffusion coefficient of colloidal particles is determined by the surface characteristics of ferrihydrite mineral discussed in previous studies. The simulations compare the biogeochemical cycling of metals considering colloidal vs. immobile phases of Fe(hydr)oxide minerals in the lake sediments. The impact of colloidal HFO particles on reactive transport and sorption of heavy metals in a natural environment, integrating coupled biotic reaction network with multiple terminal electron acceptors is presented.

The simulation results show that the colloidal HFO runs indicate a significant difference in results when advective transport of solutes (and HFO) is considered, as opposed to pure diffusive transport of ions and colloidal particles in this system. The increase in flow velocity observed to result in an increase in the transport of heavy metals with depth with increases in heavy metal profiles, indicating the importance of colloidal transport in the presence of especially advective transport. Hence, the results of the study reveal that when the potential transport of sorbed contaminants with colloidal particles are ignored, the contaminant concentrations in aqueous environments might be underestimated.

How to cite: Şengör, S. S. and Ünlü, K.: Colloid-facilitated Transport of Heavy Metals in Lake Sediments, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4924, https://doi.org/10.5194/egusphere-egu22-4924, 2022.

Per- and polyfluoroalkyl substances (PFAS) are a group of man-made chemicals used in a variety of industries around the globe since the 1940s due to their water- and oil-repellent properties. Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) have been the most extensively produced and studied of these chemicals and their toxicity has been well characterized in humans and animal models. Both chemicals are very persistent in the environment and in the human body – meaning they don’t break down and they can accumulate over time. Currently, environmental and epidemiological PFAS analysis is predominantly based on high-performance liquid chromatography (HPLC) coupled with tandem mass spectrometry (MS/MS). As the conventional analytical methods for the detection of PFASs utilize techniques based on ion-pair extraction of the analytes and quantification by MS, they can detect concentrations as low as ppt. However, they typically require, off-site analyses, are very time consuming, relatively expensive and matrix-matched calibration standards should be routinely employed. Furthermore, although these methods have demonstrated reliable results, substantial challenges still exist in increasing the number of PFASs detected and quantified in a single analytical run, working with varied sample matrices, and developing more efficient sample preparation strategies. The development of sensors to detect contaminants in environmental samples is a growing topic in environmental monitoring and management. Many limitations within existing methods of PFAS determination can be addressed through the development of PFAS-detecting sensors. One promising and sophisticated spectroscopic technique is Surface-Enhanced Raman Spectroscopy (SERS), which combines the detection limits of chromatographic techniques and the versatility and speed of the spectroscopic ones. SERS has great potential as an analytical technique based on the unique molecular signatures presented even by structurally similar analyte species and the minimal interference of scattering from water when sampling in aqueous environments. Since the SERS method can provide information which ascertains chemical and molecular composition of a sample, it is usually regarded as a promising tool suitable for the selective detection of pollutants. In this study, Surface Enhanced Raman Scattering (SERS) is explored towards the fast, accurate and versatile identification and quantification of several PFAS along with their possible degradation and transformation products. To that end, different approaches is followed, based mainly on the designed modification/functionalization of Au and Ag nanoparticles (NPs) in colloidal suspensions and the exploitation of the adsorption selectivity of Metal Organic Frameworks for PFAS in order to develop MOF-based SERS substrates. This novel and challenging task bearing both scientific and technological aspects will potentially lead to the development of a sensitive and robust SERS application for PFAS detection suitable for environmental and/or biomonitoring.

Acknowledgments: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No101037509.

How to cite: Lada, Z., Mathioudakis, G., Soto Beobide, A., Andrikopoulos, K., and Voyiatzis, G.: In the exploration of novel Surface Enhanced Raman (SERS) approaches towards the challenging detection of Per- and polyfluoroalkyl substances (PFAS), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12906, https://doi.org/10.5194/egusphere-egu22-12906, 2022.