Biography

I have a Master's degree in biotechnology/environmental microbiology from the Agricultural University of Norway (1995-2000) in Ås, now Norwegian University of Life Sceinces, NMBU. My Master thesis was about bioremediation of PCB contaminated soil by using genetically modified bacteria (Pseudomonas putida). After graduation I worked as an assistant professor at the University College of Telemark for a short period, teaching (among other things) basic toxicology and physiology. Later I worked for about 14 years for the Agricultural Inspection Service/Norwegian Food Safety Authority, working with environmental exposure assessment/modelling and risk assessment of plant protection products/pesticides. In August 2015 i started a PhD (within the Smartcrop project) here at NIBIO and the thesis was apporved in March and defended in May 2019. From 1. January 2019 I have a permanent position at NIBIO as a Researcher at the Department of Pesticides and Natural Products Chemistry. Among other things, I will be leading several projects financed by the Action plan for the sustainable use of pesticides 2016-2020; "The effect of vegetated buffer zones  runoff of pesticides", "Risk tables for evaluating the risk for pesticide leaching",  "Evaluation of the Norwegian surface water runoff scenarios", all of which are to be finalized in 2021/22. Furthermore, I will lead the projects "Updating the WISPE model and the Norwegian surface water runoff scenarios" and "Transport of pesticides in vegetated buffer zones with macroporous soil". Part from that I participate in other bigger or smaller projects in which my role is to use different exposure models to evaluate the risk of leaching, surface runoff or persistence of pesticides in soil.

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Abstract

Field and laboratory studies show increased leaching of pesticides through macropores in frozen soil. Fast macropore flow has been shown to reduce the influence of pesticide properties on leaching, but data on these processes are scarce. The objective of this study was to investigate the effect of soil freezing and thawing on transport of pesticides with a range of soil sorption coefficients (Kf). To do this we conducted a soil column study to quantify the transport of bromide and five pesticides (2-methyl-4-chlorophenoxyacetic acid, clomazone, boscalid, propiconazole, and diflufenican). Intact topsoil and subsoil columns from two agricultural soils (silt and loam) in southeastern Norway were used in this experiment, and pesticides were applied to the soil surface in all columns. Half the columns were then frozen (−3°C), and the other half were left unfrozen (4°C). Columns were subjected to repeated irrigation events where 25 mm of rainwater was applied during 5 h at each event. Irrigations were followed by 14-d periods of freezing or refrigeration. Percolate was collected and analyzed for pesticides and bromide. Pesticide leaching was up to five orders of magnitude larger from frozen than unfrozen columns. Early breakthrough (<<1 pore volume) of high concentrations was observed for pesticides in frozen columns, indicating that leaching was dominated by preferential flow. The rank order in pesticide leaching observed in this study corresponded to the rank order of mean Kf values for the pesticides, and the results suggest that sorption plays a role in determining leaching losses even in frozen soil.

To document See dataset

Abstract

Limited knowledge and experimental data exist on pesticide leaching through partially frozen soil. The objective of this study was to better understand the complex processes of freezing and thawing and the effects these processes have on water flow and pesticide transport through soil. To achieve this we conducted a soil column irrigation experiment to quantify the transport of a non-reactive tracer and the herbicide MCPA in partially frozen soil. In total 40 intact topsoil and subsoil columns from two agricultural fields with contrasting soil types (silt and loam) in South-East Norway were used in this experiment. MCPA and bromide were applied on top of all columns. Half the columns were then frozen at −3 °C while the other half of the columns were stored at +4 °C. Columns were then subjected to repeated irrigation events at a rate of 5 mm artificial rainwater for 5 h at each event. Each irrigation was followed by 14-day periods of freezing or refrigeration. Percolate was collected and analysed for MCPA and bromide. The results show that nearly 100% more MCPA leached from frozen than unfrozen topsoil columns of Hov silt and Kroer loam soils. Leaching patterns of bromide and MCPA were very similar in frozen columns with high concentrations and clear peaks early in the irrigation process, and with lower concentrations leaching at later stages. Hardly any MCPA leached from unfrozen topsoil columns (0.4–0.5% of applied amount) and concentrations were very low. Bromide showed a different flow pattern indicating a more uniform advective-dispersive transport process in the unfrozen columns with higher con- centrations leaching but without clear concentration peaks. This study documents that pesticides can be pre- ferentially transported through soil macropores at relatively high concentrations in partially frozen soil. These findings indicate, that monitoring programs should include sampling during snow melt or early spring in areas were soil frost is common as this period could imply exposure peaks in groundwater or surface water.

Abstract

To ensure compliance with food safety regulations, monitoring programs and reliable analytical methods to detect relevant chemical pollutants in food and the environment are key instruments. Pesticides are an important part of pest management in agriculture to sustain and increase crop yields and control post-harvest decay, while pesticide residues in food may pose a risk to human health. Thus, the levels of pesticide residues in food must be controlled and should align with Maximum Residue Levels regulations to ensure food safety. Food safety monitoring programs and analytical methods for pesticide residues and metabolites are well developed. Future developments to ensure food safety must include the increased awareness and improved regulatory framework to meet the challenges with natural toxins, emerging contaminants, novel biopesticides, and antimicrobial resistance in food and the environment. The reality of a complex mixture of pollutants, natural toxins, and their metabolites potentially occurring in food and the environment implies the necessity to consider combined effects of chemicals in risk assessment. Here, we present challenges, monitoring efforts, and future perspectives for chemical food safety focused on the importance of current developments in high-resolution mass spectrometry (HRMS) technologies to meet the needs in food safety and environmental monitoring.

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Abstract

The use of Bayesian networks (BN) for environmental risk assessment has increased in recent years as they offer a more transparent way to characterize risk and evaluate uncertainty than the traditional risk assessment paradigms. In this study, a novel probabilistic approach applying a BN for risk calculation was further developed and explored by linking the calculation a risk quotient to alternative future scenarios. This extended version of the BN model uses predictions from a process-based pesticide exposure model (World Integrated System for Pesticide Exposure - WISPE) in the exposure characterization and toxicity test data in the effect characterization. The probability distributions for exposure and effect are combined into a risk characterization (i.e. the probability distribution of a risk quotient), a common measure of the exceedance of an environmentally safe exposure threshold. The BN model was used to account for variabilities of the predicted pesticide exposure in agricultural streams, and inter-species variability in sensitivity to the pesticide among freshwater species. In Northern Europe, future climate scenarios typically predict increased temperature and precipitation, which can be expected to cause an increase in weed infestations, plant disease and insect pests. Such climate-related changes in pest pressure in turn can give rise to altered agricultural practices, such as increased pesticide application rates, as an adaptation to climate change. The WISPE model was used to link a set of scenarios consisting of two climate models, three pesticide application scenarios and three periods (year ranges), for a case study in South-East Norway. The model was set up for the case study by specifying environmental factors such as soil properties and field slope together with chemical properties of pesticides to predict the pesticide exposure in streams adjacent to the agricultural fields. The model was parameterized and evaluated for five selected pesticides: the three herbicides clopyralid, fluroxypyr-meptyl, and 2-(4-chloro-2-methylphenoxy) acetic acid (MCPA), and the two fungicides prothiocanzole and trifloxystrobin. This approach enabled the calculation and visualization of probability distribution of the risk quotients for the future time horizons 2050 and 2085. The risk posed by the pesticides were in general low for this case study, with highest probability of the risk quotient exceeding 1 for the two herbicides fluroxypyr-meptyl and MCPA. The future climate projections used here resulted in only minor changes in predicted exposure concentrations and thereby future risk. However, a stronger increase in risk was predicted for the scenarios with increased pesticide application, which can represent an adaptation to a future climate with higher pest pressures. In the current study, the specific BN model predictions were constrained by an existing set of climate projections which represented only one IPCC scenario (A1B) and two climate models. Further advancement of the BN modelling demonstrated herein, including more recent climate scenarios and a larger set of climate models, is anticipated to result in more relevant risk characterization also for future climate conditions. This probabilistic approach will have the potential to aid targeted management of ecological risks in support of future research, industry and regulatory needs.

Abstract

Future weather patterns are expected to result in increased precipitation and temperature, in Northern Europe. These changes can potentially cause an increase in plant disease and insect pests which will alter agricultural practice amongst other things the used crop types and application patterns of pesticides. We use a Bayesian network to explore a probabilistic risk assessment approach to better account for variabilities and magnitudes of pesticide exposure to the aquatic ecosystem. As Bayesian networks link selected input and output variables from various models and other information sources, they can serve as meta-models. In this study, we are using a pesticide fate and transport models (e.g. WISPE) with specific environmental factors such as soil and site parameters together with chemical properties and climate scenarios that are linked to a representative Norwegian study area. The derived exposure of pesticide of the study area is integrated in the Bayesian network model to estimate the risk to the aquatic ecosystem also integrating an effect distribution derived from toxicity test. This Bayesian network model will allow to incorporate climate predictions into ecological risk assessment.

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Abstract

Difenoconazole is a widely used triazole fungicide that has been frequently detected in the environment, but comprehensive study about its environmental fate and toxicity of potential transformation products (TPs) is still lacking. Here, laboratory experiments were conducted to investigate the degradation kinetics, pathways, and toxicity of transformation products of difenoconazole. 12, 4 and 4 TPs generated by photolysis, hydrolysis and soil degradation were identified via UHPLC-QTOF/MS and the UNIFI software. Four intermediates TP295, TP295A, TP354A and TP387A reported for the first time were confirmed by purchase or synthesis of their standards, and they were further quantified using UHPLC-MS/MS in all tested samples. The main transformation reactions observed for difenoconazole were oxidation, dechlorination and hydroxylation in the environment. ECOSAR prediction and laboratory tests showed that the acute toxicities of four novel TPs on Brachydanio rerio, Daphnia magna and Selenastrum capricornutum are substantially lower than that of difenoconazole, while all the TPs except for TP277C were predicted chronically very toxic to fish, which may pose a potential threat to aquatic ecosystems. The results are important for elucidating the environmental fate of difenoconazole and assessing the environmental risks, and further provide guidance for scientific and reasonable use.

Abstract

Plantevernmidler er et viktig verktøy i dagens plantevernpraksis i jordbruket for å sikre gode avlinger. Miljørisikoen knyttet til det enkelte plantevernmiddel vurderes nøye før det godkjennes for bruk, men langvarig overvåking er nødvendig for å avdekke de faktiske miljøkonsentrasjoner og - effekter etter forskriftsmessig bruk av plantevernmidler. Sveriges nasjonale miljøovervåkingsprogram for plantevernmidler startet i 2002. Hovedmålet med programmet er å følge langtidstrender i påvirkningen av jordbrukets plantevernmiddelbruk på kvaliteten av overflate- og grunnvann, samt å bestemme miljøkonsentrasjonene av plantevernmidler i sediment, luft og nedbør. Formålet med denne evalueringen var å vurdere styrker og svakheter ved overvåkingsprogrammet, samt behov for endringer i den praktiske gjennomføringen, rapporteringsprosedyrer og målsetningen med programmet. Denne evalueringen vurderer også behovene hos de aktuelle sluttbrukergruppene for programmet som inkluderer svensk landbruks- og miljøforvaltning, rådgivningstjenesten i landbruket, bønder og bondeorganisasjoner mv.

Abstract

In Northern Europe, future changes in land-use and weather patterns are expected to result in increased precipitation and temperature this may cause an increase in plant disease and insect pests. In addition, predicted population increase will change the production demands and in turn alter agricultural practices such as crop types and with that the use pattern of pesticides. Considering these variabilities and magnitudes of pesticide exposure to the aquatic environment still needs to be accounted for better in current probabilistic risk assessment. In order to improve ecological risk assessment, this study explores an alternative approach to probabilistic risk assessment using a Bayesian Network, as these can serve as meta-models that link selected input and output variables from other models and information sources. The developed model integrates variability in both exposure and effects in the calculation of risk estimate. We focus on environmental risk of pesticides in two Norwegian case study region representatives of northern Europe. Using pesticide fate and transport models (e.g. WISPE), environmental factors such as soil and site parameters together with chemical properties and climate scenarios (current and predicted) are linked to the exposure of a pesticide in the selected study area. In the long term, the use of tools based on Bayesian Network models will allow for a more refined assessment and targeted management of ecological risks by industry and policy makers.

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Abstract

Preferential flow may become significant in partially frozen soils because infiltration can occur through large, initially air-filled pores surrounded by a soil matrix with limited infiltration capacity. The objectives of this study were to develop and evaluate a dual-permeability approach for simulating water flow and heat transport in macroporous soils undergoing freezing and thawing. This was achieved by introducing physically based equations for soil freezing and thawing into the dual-permeability model MACRO. Richards’ equation and the heat flow equation were loosely coupled using the generalized Clapeyron equation for the soil micropore domain. Freezing and thawing of macropore water is governed by a first-order equation for energy transfer between the micropore and macropore domains. We assumed that macropore water was unaffected by capillary forces, so that water in macropores freezes at 0°C. The performance of the model was evaluated for four test cases: (i) redistribution of water in the micropore domain during freezing, (ii) a comparison between the first-order energy transfer approach and the heat conduction equation, (iii) infiltration and water flow in frozen soil with an initially air-filled macropore domain, and (iv) thawing from the soil surface during constant-rate rainfall. Results show that the model behaves in accordance with the current understanding of water flow and heat transport in frozen macroporous soil. To improve modeling of water and heat flow in frozen soils, attention should now be focused on providing experimental data suitable for evaluating models that account for macropore flow.

To document See dataset

Abstract

Field and laboratory studies show increased leaching of pesticides through macropores in frozen soil. Fast macropore flow has been shown to reduce the influence of pesticide properties on leaching, but data on these processes are scarce. The objective of this study was to investigate the effect of soil freezing and thawing on transport of pesticides with a range of soil sorption coefficients (Kf). To do this we conducted a soil column study to quantify the transport of bromide and five pesticides (2-methyl-4-chlorophenoxyacetic acid, clomazone, boscalid, propiconazole, and diflufenican). Intact topsoil and subsoil columns from two agricultural soils (silt and loam) in southeastern Norway were used in this experiment, and pesticides were applied to the soil surface in all columns. Half the columns were then frozen (−3°C), and the other half were left unfrozen (4°C). Columns were subjected to repeated irrigation events where 25 mm of rainwater was applied during 5 h at each event. Irrigations were followed by 14-d periods of freezing or refrigeration. Percolate was collected and analyzed for pesticides and bromide. Pesticide leaching was up to five orders of magnitude larger from frozen than unfrozen columns. Early breakthrough (<<1 pore volume) of high concentrations was observed for pesticides in frozen columns, indicating that leaching was dominated by preferential flow. The rank order in pesticide leaching observed in this study corresponded to the rank order of mean Kf values for the pesticides, and the results suggest that sorption plays a role in determining leaching losses even in frozen soil.

To document

Abstract

Freezing and thawing have large effects on water flow in soils since ice may block a large part of the pore space and thereby prevent infiltration and flow through the soil. This, in turn, may have consequences for contaminant transport. For example, transport of solutes contained at or close to the soil surface can be rapidly transported through frozen soils in large pores that were air filled at the time of freezing. Accounting for freezing and thawing could potentially improve model predictions used for risk assessment of contaminant leaching. A few numerical models of water flow through soil accounts for freezing by coupling Richards’ equation and the heat flow equation using of the generalized Clapeyron equation, which relates the capillary pressure to temperature during phase change. However, these models are not applicable to macroporous soils. The objective of this study was to develop and evaluate a dual-permeability approach for simulating water flow in soil under freezing and thawing conditions. To achieve this we extended the widely used MACRO-model for water flow and solute transport in macroporous soil. Richards’ equation and the heat flow equation were loosely coupled using the Clapeyron equation for the soil micropore domain. In accordance with the original MACRO model, capillary forces were neglected for the macropore domain and conductive heat flow in the macropores was not accounted for. Freezing and thawing of macropore water, hence, were solely governed by heat exchange between the pore domains. This exchange included a first-order heat conduction term depending on the temperature difference between domains and the diffusion pathlength (a proxy variable related to the distance between macropores) and convective heat flow. As far as we know, there are no analytical solutions available for water flow during freezing and thawing and laboratory data is limited for evaluation of water flow through macropores. In order to evaluate the new model approach we therefore first compared simulation results of water flows during freezing for the micropore domain to existing literature data. Our model was shown to give similar results as other available models. We then compared the first-order conductive heat exchange during freezing to a full numerical solution of heat conduction. Finally, simulations were run for water flow through frozen soil with initially air-filled macropores for different boundary conditions. Simulation results were sensitive to parameters governing the heat exchange between pore domains for both test cases.

To document See dataset

Abstract

Limited knowledge and experimental data exist on pesticide leaching through partially frozen soil. The objective of this study was to better understand the complex processes of freezing and thawing and the effects these processes have on water flow and pesticide transport through soil. To achieve this we conducted a soil column irrigation experiment to quantify the transport of a non-reactive tracer and the herbicide MCPA in partially frozen soil. In total 40 intact topsoil and subsoil columns from two agricultural fields with contrasting soil types (silt and loam) in South-East Norway were used in this experiment. MCPA and bromide were applied on top of all columns. Half the columns were then frozen at −3 °C while the other half of the columns were stored at +4 °C. Columns were then subjected to repeated irrigation events at a rate of 5 mm artificial rainwater for 5 h at each event. Each irrigation was followed by 14-day periods of freezing or refrigeration. Percolate was collected and analysed for MCPA and bromide. The results show that nearly 100% more MCPA leached from frozen than unfrozen topsoil columns of Hov silt and Kroer loam soils. Leaching patterns of bromide and MCPA were very similar in frozen columns with high concentrations and clear peaks early in the irrigation process, and with lower concentrations leaching at later stages. Hardly any MCPA leached from unfrozen topsoil columns (0.4–0.5% of applied amount) and concentrations were very low. Bromide showed a different flow pattern indicating a more uniform advective-dispersive transport process in the unfrozen columns with higher con- centrations leaching but without clear concentration peaks. This study documents that pesticides can be pre- ferentially transported through soil macropores at relatively high concentrations in partially frozen soil. These findings indicate, that monitoring programs should include sampling during snow melt or early spring in areas were soil frost is common as this period could imply exposure peaks in groundwater or surface water.

To document

Abstract

This is a final report for the project Norwegian Scenarios II, part two, that has been performed in collaboration between Bioforsk Plant Health and Plant Protection, The Norwegian University of Life Sciences and the Norwegian Food Safety Authority. The aim of the project was to establish Norwegian scenarios for the models PRZM and MACRO and to use them for approval of new pesticides.