Results of microcosm experiments with groundwater bacteria indicated on its degradation potential. PCR analysis of microcosms cultures has shown the presence of atzA and trzN genes. Furthermore, LC-MS analysis of groundwater extracts identified a large proportion of atrazine degradation products indicating on ongoing degradation in the field. Further isotope analysis of atrazine in  groundwater extracts will provide an additional line of evidence for ongoing degradation in groundwater.

How to cite: Arar, M. and Bernstein, A.: Microbial degradation of Atrazine in Groundwater, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-454, https://doi.org/10.5194/egusphere-egu22-454, 2022.

The strength of the interaction between a pesticide and the soil organic matter is a key parameter to assess the risk of it reaching to groundwater with potentially harmful effects to human health. The humic substances (HS) play important role in the adsorption of pesticides. The mechanism of these reactions includes cation exchange, chelation, coordination, hydrogen bonding, charge transfer, hydrofobic bonding, π bonding, and van der Waals bonding. Many factors could affect the pesticide signals in LC-MS/MS analysis.  The chemical and physical properties of the analytes and the composition of the sample matrix are amongst them. Acidification of the solution can also affect the ionization of analytes (pesticides) in the ion source.

In this work, a approach that allows measuring such pesticide interactions  in acidic solutions (formic acid - FA, acetic acid - AA). These were representatives of pesticides phenoxycarboxylic, chloroacetanilide, urea, organophosphate, triazine, triazole and representatives of other pesticides. The measurements showed that different groups of pesticides exhibit different behaviors in the presence of humic acids. There were differences both between different groups of pesticides and between individual representatives within certain groups.

The resulting measured concentration values differed most from each other for organophosphate pesticides. At the same time, the structures of the molecules of these pesticides vary greatly. Dimethoat had a more pronounced signal drop than diazinon at lower pesticide concentrations (25 ng/l). The effect of the addition of FA and AA on the resulting concentration values also differed between the two pollutants studied. In diazinon, the addition of AA signal decreased in dimethoat, on the contrary, increased. The addition of FA in diazinon further dampened the signal, while dimethoat experienced a similar increase in analyte values as with the addition of AA. From the results of the measurements, it can be deduced that representatives of organophosphate pesticides show different behavior in the presence of HA.

How to cite: Kříženecká, S.: Influence of sample acidification in the presence of humic substances in determination of pesticide by LC-MS/MS, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7082, https://doi.org/10.5194/egusphere-egu22-7082, 2022.

Urban biocides like terbutryn are used in construction materials such as render and paints on façades to prevent the growth of algae and fungi. With wind-driven rain, those contaminants leach into the environment and pose a risk for groundwater contamination. In our study, we combined leaching experiments with artificial facades to quantify biocide release, lysimeter experiments to get insights into the reactive transport under environmental conditions, and field sampling in an urban catchment to follow-up biocide release from source (building facades) to sinks (stormwater retention systems/ groundwater). We use concentrations of terbutryn as well as its four major transformation products to establish mass balances. Furthermore, we use Compound-Specific Isotope Analysis (CSIA) as a concentration-independent tool to identify the dominant degradation processes in the environment by taking into account (i) isotopic enrichment of stable isotopes by dual-isotope plots and (ii) patterns of formed transformation products. Façade leaching experiments show that high quantities of terbutryn remain on the facades and leaching continues for a long period. Transformation products are already formed on the facades through photodegradation. Reactive transport on typical urban surfaces (gravel, paved stones with joints, soil) indicates high retention of terbutryn in the grass lysimeter and faster leaching in gravel and pavement lysimeters with low recoveries of terbutryn in the first 2 months (3 %, 1 % and <1 % in gravel, paved and grass lysimeter, respectively). In all lysimeters, transformation products were formed, exceeding the concentrations of leached terbutryn at some sampling points, indicating higher mobility through better solubility in water of the daughter compounds. The overall extend of (bio-)degradation in the lysimeters was low for terbutryn, as supported by CSIA data (changes in Δδ¹³C < 2‰). Grab samples in a stormwater retention pond and swale system in an urban catchment confirmed the leaching of terbutryn and transformation products in a catchment from 6-year-old buildings with concentrations of terbutryn between 3 and 70 ng/L, as well as TP terbutryn sulfoxide, exceeding 400 ng/L. Our study implies the importance of detailed monitoring of urban biocides to understand the reactive transport processes on their pathways into groundwater and underlines the importance of monitoring also transformation products in typical monitoring schemes.

How to cite: Junginger, T., Payraudeau, S., and Imfeld, G.: The Urban Biocide Terbutryn: Field investigations to explore release and reactive transport under environmental conditions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5104, https://doi.org/10.5194/egusphere-egu22-5104, 2022.

Urban swales collect stormwater runoff containing micropollutants such as biocides washed off from facades during wind driven rain. Although swales retain contaminants, they might eventually reach groundwater through soil. However, there is little data available of biocide occurrence in urban swale sediment. In this study, we measured the biocide entry to an urban swale and its distribution in sediment. The selected swale in south-west Germany collects runoff from a 3 ha residential area with 46 houses. Two pipes lead into the swale, one collecting runoff from a 1 ha area (“East”) and one from a 2 ha area (“West”). We took sediment samples after dry and wet periods close to both pipes and additional water grab samples during wet periods. In total, we collected 19 stormwater samples during 7 events and 116 sediment samples during 8 days over a period of two years. Water samples were analyzed for three biocides (diuron, terbutryn, octylisothiazoline= OIT) and four transformation products (= TPs, diuron-desmethyl, terbuthylazine-2-hydroxy, terbutryn-desethyl, terbumeton) using LC-MS/MS. Sediment samples were analyzed for terbutryn, OIT and 3 TPs of terbutryn. Finally, we linked a water balance model to a leaching model and simulated longterm biocide input into the swale. This we compared with biocide concentration in the swale sediments using a mass balance approach. We found all biocides and all TPs in water samples at both pipes confirming biocide input to the swale. In the sediment, terbutryn concentrations were generally below 1 ng/g. Of three measured TPs of terbutryn we detected only one, terbutryn-desethyl (<1 ng/g dry weight). There were no significant differences of terbutryn concentration in the sediment before and after storm events. This suggests continuous input and long presence of biocides. Concentrations at pipe West were higher than at pipe East. This pointed to differences in the connected areas such as differences in paints used at individual houses. At the outlet of pipe West, we found maximum concentrations of terbutryn (26 ng/g) in saturated sediments below standing water, which suggests more sorption and less degradation at this location. We thus assume that dry condition in swales during dry weather promote degradation. Overall, our findings emphasize that not only the quantity of urban runoff should guide the design of urban swale systems but also potential biocide entry.

How to cite: Linke, F., Schnarr, L., Olsson, O., Kümmerer, K., Preusser, F., Leistert, H., Bork, M., and Lange, J.: Measuring and modeling biocide entry from facades in urban swale sediment , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4334, https://doi.org/10.5194/egusphere-egu22-4334, 2022.

Modelling environmental concentrations of pesticides at landscape-level is of growing interest for pesticide registration and product stewardship, including higher-tier studies in risk assessment, mitigation measures, monitoring support and decision making. Typically, runoff, drainage, and leaching are taken into account, using different modelling concepts. However, the modelling of spray drift often is simplified or neglected in landscape-level models. For example, the Soil and Water Assessment Tool (SWAT) does not consider spray drift for pesticide transport simulation. Hence, external offline calculations of spray drift are necessary, with the pesticide masses added to the channel network via point sources. Although this is a pragmatic solution for including spray drift, future scientific questions in high spatial and temporal resolution require adequate integrated processes on landscape‑level. Hence, the goal of this project is to: (i) develop and validate a standalone spray drift model that can be used with other modelling approaches in a modular manner, and (ii) implement that model into SWAT+.

Our spray drift model consists of two parts. First, a mechanistic droplet model predicts the trajectories of individual droplets. Second, a 2D Gaussian diffusion model predicts longitudinal advection as well as vertical and lateral dispersion of droplets. This modelling approach allows for a reasonable tradeoff between accuracy and computational expenses. The following inputs are considered: (i) weather conditions, (ii) drop size distribution, (iii) physio‑chemical properties of the active ingredient, and (iv) operational characteristics (e.g., nozzle count, boom height and width, applied amounts and volumes, and forward driving speed).

It is planned to validate the model against an ensemble of computational fluid dynamics simulations. Additionally, the approach will be evaluated using high resolution SWAT+ models of medium sized agriculturally dominated catchments in Germany. We expect the implementation of spray drift to improve modelling performance for different research questions e.g., the sensitivity of aquatic pesticide concentrations on landscape-level regarding application timing.

How to cite: Fuchs, M., Gebler, S., and Lorke, A.: High resolution exposure modelling at landscape-level – on the development of a mechanistic drift module for SWAT+, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3887, https://doi.org/10.5194/egusphere-egu22-3887, 2022.

In Sweden farmers are legally obliged to apply for permits for pesticide use if their land lies within a drinking water abstraction zone. The standalone modelling tool MACRO-DB 4 developed by the Swedish University of Agricultural Sciences (SLU) is available for risk assessment and decision support. MACRO-DB 4 is used by local authorities, farmers/landowners and consultants, and is based on the well-established leaching model MACRO 5.2. However, the software is costly to maintain and slow for end users. Hence, a robust meta-model of MACRO-DB 4 was developed and integrated in a web-based tool (MACRO DB Steg2 v.5) that is fast, easy to maintain, and easy to understand for stakeholders. The meta-model (implemented as an R package) is based on i) a large number of MACRO simulations for the whole agriculturally relevant area of Sweden, and ii) a trilinear interpolation tool. The simulations comprised 18 climates, 72 soils, 1 typical crop (spring cereals), 3 application seasons (spring, summer and autumn), and 150 dummy compounds consisting of a grid of normalized Freundlich coefficient Koc, degradation half-life at reference conditions DT50 and Freundlich exponent. Target variables were i) the mean leaching flux concentration over 20 years at 2 m depth (PECgw), and ii) the 20-year mean concentration in large surface water bodies (PECsw; based on pesticide inputs via drainage and baseflow) . The meta-model performs a trilinear interpolation (in the three-dimensional space of Koc, DT50 and Freundlich exponent) for log10 of PECgw or PECsw, respectively. Different crops are taken into account in the web-based tool by adjusting the pesticide interception fraction according to the BBCH stage of the crop to be modelled at the time of application. In order to identify the most important input factors for PECgw and PECsw, a variance-based Global Sensitivity Analysis (GSA) was performed for the MACRO meta-model using the Sobol’ method. This method allows to i) identify first-order (direct) and higher-order (interaction) effects for each input factor (climate, soil, application season, Koc, DT50 and Freundlich exponent), and ii) rank the input factors according to their importance.

How to cite: Pohlert, T., Reichenberger, S., Multsch, S., Jarvis, N., and Gönczi, M.: Global Sensitivity Analysis for a MACRO Meta-Model for Swedish Drinking Water Abstraction Zones, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-832, https://doi.org/10.5194/egusphere-egu22-832, 2022.

Zinc-based and Cu-based fungicides are widely used in European vineyards to prevent fungal diseases. The soil management and rainfall characteristics influence the runoff export of copper (Cu) and zinc (Zn) from vineyard plots, although quantitative field studies are mostly missing. The runoff exports of Zn and Cu from Northern vineyard plots (Rouffach, Alsace, calcareous-loamy soils with pH = 8.0) under conventional and alternative soil management were compared during two contrasting vine-growing seasons. The conventional management included standard soil maintenance with chemical weeding, whereas the alternative management involved the conversion to organic farming with a mechanical soil management. Cu in top-soil, i.e. the first 5 cm, reached 103.6 ± 19.1 and 70.8 ± 7.8 kg Cu ha^-1 for conventional and alternative plots, respectively, mirroring accumulation since decades. Zn in top-soil reached 70.8 ± 16.4 and 63.9 ± 7.8 kg Cu ha^-1 for conventional and alternative plots, respectively. No Zn applications on the conventional and alternative plots were recorded during the two growing seasons. Overall, our results emphasize that destructuring of the surface soil layer and tillage preceding a storm event largely influences water flows and exports of both dissolved and solid-bound Cu and Zn. Plowing work on the organic plot a few days before a most intense storm event resulted in significant mass export, accounting for 99% and 95% of the total mass exported during the vine-growing season for Cu and Zn, respectively. However, grass cover on one out of two inter-rows limited runoff volumes to a maximum runoff coefficient of up to 1.4% over the two vine-growing seasons. The seasonal export of Cu and Zn occurred mainly by surface runoff as the monthly water storage of the soil was lower than the water holding capacity, thereby limiting vertical flows in both management modes. The mass export of solid-bound Cu and Zn contributed to more than 95% of total export of both Cu and Zn from the vineyard plots. The seasonal Cu and Zn exports ranged from 0.001 to 0.05% of historical Cu and Zn in the top-soil, raising the issue of both Cu and Zn accumulation in vineyard soils. Altogether, this study underscores that soil mechanical management preceding a storm event largely affects Cu and Zn export, although Cu and Zn fluxes in runoff from the alternative management are globally lower. 

How to cite: Payraudeau, S., Meite, F., and Imfeld, G.: Soil management affects copper and zinc export in runoff from Northern vineyard plots (Rouffach, Alsace, France), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11685, https://doi.org/10.5194/egusphere-egu22-11685, 2022.

The management of urban stormwater runoff has moved from approaches narrowly focused on reducing flooding to approaches more focused on improving water quality. From impervious surfaces, stormwater is often diverted into retention ponds where sedimentation is used to limit the impact on waterbodies by trapping particulate pollutants. Trace elements are of particular interest because of their potential toxicity. The composition of the sediment varies over time, particularly through the development of vegetation. Ageing has an effect on sediment removal ability of pollutants (Nuel et al., 2018). The aim of this study was to compare the mobility of trace elements in sediments of a retention-infiltration pond before and after its total dredging. The mobility of these pollutants is related to their geochemical fractionation between solid phases which is generally investigated by extraction methods. The single extraction method with ammonium acetate and calcium chloride was applied on sediment samples to quantify the highest labile fraction of these elements (Sakan et al., 2020). The ultrasound assisted sequential extraction based on the procedure proposed by Rauret et al., (2000) and certified by Pueyo et al., (2001) was applied to determine the pollutant distribution among the acid-extractable, reducible, oxidizable fractions of sediments. The ageing effect is examined to explain the global removal ability of sediments. Then, the distribution of trace elements in different solid phases is analyzed in function of the sediment ageing, the mineral composition and granulometry of sediments.

Nuel, M., Laurent, J., Bois, P., Heintz, D., Wanko, A., 2018. Seasonal and ageing effect on the behaviour of 86 drugs in a full-scale surface treatment wetland: Removal efficiencies and distribution in plants and sediments. Science of The Total Environment 615, 1099–1109. https://doi.org/10.1016/j.scitotenv.2017.10.061

Pueyo, M., Rauret, G., Lück, D., Yli-Halla, M., Muntau, H., Quevauviller, Ph., López-Sánchez, J.F., 2001. Certification of the extractable contents of Cd, Cr, Cu, Ni, Pb and Zn in a freshwater sediment following a collaboratively tested and optimised three-step sequential extraction procedure. J. Environ. Monitor. 3, 243–250. https://doi.org/10.1039/b010235k

Rauret, G., López-Sánchez, J.-F., Sahuquillo, A., Barahona, E., Lachica, M., Ure, A.M., Davidson, C.M., Gomez, A., Lück, D., Bacon, J., Yli-Halla, M., Muntau, H., Quevauviller, Ph., 2000. Application of a modified BCR sequential extraction (three-step) procedure for the determination of extractable trace metal contents in a sewage sludge amended soil reference material (CRM 483), complemented by a three-year stability study of acetic acid and EDTA extractable metal content. J. Environ. Monitor. 2, 228–233. https://doi.org/10.1039/b001496f

Sakan, S., Frančišković-Bilinski, S., Đorđević, D., Popović, A., Škrivanj, S., Bilinski, H., 2020. Geochemical Fractionation and Risk Assessment of Potentially Toxic Elements in Sediments from Kupa River, Croatia. Water 12, 2024. https://doi.org/10.3390/w12072024

How to cite: Dang, D. P. T., Jean-Soro, L., and Béchet, B.: Evaluation of ageing effect on trace element mobility in sediment of sustainable drainage systems by chemical extractions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5848, https://doi.org/10.5194/egusphere-egu22-5848, 2022.

Regulatory exposure assessments (EA) are a cornerstone in the registration of new or existing agrochemicals in the EU, USA and many other countries to preserve ecosystem health and water quality. VFSMOD (Muñoz-Carpena et al., 1999; 2004) is a numerical, storm-based design model that quantifies the performance of vegetative filter strips- VFS (grass buffers) to mitigate pesticide runoff into surface waters. The model has been coupled into current USA and EU long-term (20 to 30 yr), higher-tier regulatory pesticide EAs to estimate potential pesticide load reductions by the VFS before entering the aquatic environment. A new comprehensive modeling component has been added to VFSMOD to quantify the fate of pesticides residue on the VFS between events in the context of long-term simulations. The aim of this study is to present the verification of the assumptions and accuracy of the new pesticide residue component within VFSMOD in the context of continuous simulations by exploring a wide range of conditions (Koc, half-life, remobilization processes) of importance to improve current understanding of quantitative mitigation of pesticides in the regulatory environment.  The results show the complex interaction in the VFS amongst surface pesticide runoff, sedimentation, infiltration and leaching, degradation, evapotranspiration and soil moisture change, and mixing layer remobilization that produces emergent behavior in the amount of pesticide residue potentially remobilized in the next event in the series.

How to cite: Muñoz-Carpena, R., Reichenberger, S., and Sur, R.: Importance of surface pesticide residues in the quantitative mitigation of pesticides with vegetative filter strips: VFSMOD development and analysis, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13039, https://doi.org/10.5194/egusphere-egu22-13039, 2022.

The most widely implemented mitigation measure to reduce transfer of pesticides and other pollutants to surface water bodies via surface runoff are vegetative filter strips (VFS). The most commonly used model for assessing the reduction of surface runoff, eroded sediment and pesticide inputs into surface water by VFS is VFSMOD, which simulates reduction of total inflow (∆Q) and reduction of incoming eroded sediment load (∆E) mechanistically. These variables are subsequently used to calculate the reduction of pesticide load by the VFS (∆P). Since errors in ∆Q and ∆E will propagate to ∆P, for strongly sorbing compounds, an accurate prediction of ∆E is crucial for a reliable prediction of ∆P. The most important parameter characterizing the incoming sediment in VFSMOD is the median particle diameter d50, which is currently fixed to 20 µm in the regulatory tool SWAN 5.01. The objective of this study was to derive an improved, generic d50 parameterization methodology that can be readily used for regulatory VFS scenarios.

A test dataset of d50 values and explanatory variables has been compiled from heterogeneous data sources. The established test dataset (n = 93) was analysed using Machine Learning techniques (Random Forest, Gradient Boosting) and multiple regression analysis (MLR). With the help of the knowledge gained with Machine Learning, a MLR equation with six predictor variables was established and thoroughly tested. Since three of the predictors are event-specific (eroded sediment yield, rainfall intensity and peak runoff rate), the predicted d50 values vary between runoff events according to their magnitude and intensity.

A modified version of SWAN-VFSMOD containing the improved d50 parameterization method was run for a number of contrasting compounds and application scenarios. The obtained ∆E and ∆P values as well as the resulting pesticide concentrations in surface water and sediment (PECsw/sed) were compared with the current FOCUS step4 approach.

How to cite: Reichenberger, S., Sur, R., Sittig, S., Multsch, S., Carmona-Cabrero, Á., and Muñoz-Carpena, R.: Impact of a new sediment parameterization method in VFSMOD on PECsw/sed in FOCUS step4, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-628, https://doi.org/10.5194/egusphere-egu22-628, 2022.

Surface runoff from agricultural fields is a major input pathway of pesticides into surface waters. The aim of this project was to i) analyze the effectiveness of various mitigation measures to reduce pesticide runoff and erosion inputs into surface waters, ii) assess the suitability of the measures found effective for use in the quantitative environmental exposure assessment for authorization of plant protection products (PPP), and iii) make recommendations how the potentially suitable measures could be applied in risk assessment of PPP in Germany. Following a literature analysis, 16 risk mitigation measures were presented to five experts for evaluation of effectiveness, cost-effectiveness, controllability, current distribution and dissemination potential. Measures finally selected for quantitative analysis belong to 3 groups: vegetative filter strips (VFS), soil conservation measures and micro-dams in row crops. Subsequently, the effectiveness of the recommended measures was evaluated based on experimental data using different statistical methods (e.g. CART, MLR, graphical methods).

The quantitative analysis confirmed the effectiveness of VFS and micro-dams. For soil conservation measures (especially mulch-till), the evaluated data showed highly variable results. This was partly caused by the heterogeneity of the experimental data, which also made it difficult to aggregate the results of different studies.

The following conclusions were drawn: Both VFS and micro-dams can be recommended for application in quantitative environmental exposure assessment for pesticides.  However, infiltration and sedimentation in VFS should be simulated with a mechanistic model such as VFSMOD. The effect of micro-dams can be modelled as a reduction of the runoff Curve Number (CN). The runoff modelling should be carried out with a model such as PRZM which adjusts the CN daily based on soil water content.

How to cite: Klein, M., Reichenberger, S., O'Connor, I., Spycher, S., Sittig, S., Multsch, S., Thomas, K., Flade, J., and Großmann, D.: Evaluation of the effectiveness of mitigation measures to reduce pesticide inputs into surface water bodies via surface runoff and erosion, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-639, https://doi.org/10.5194/egusphere-egu22-639, 2022.