Marianne Stenrød

Head of Department/Head of Research

(+47) 482 97 607
marianne.stenrod@nibio.no

Place
Ås H7

Visiting address
Høgskoleveien 7, 1433 Ås

Biography

My research focus on effects of soil and climate conditions on degradation and transport of pesticides in the environment and impacts of pesticides on microbial acitivty in soil. I finished my PhD-studies on effects of pedoclimatic conditions on the degradation of glyphosate in soil at NMBU in 2005. I head several nationally funded research projects on these topics and am responsible for the pesticide monitoring within the Norwegian Agricultural Environmental Monitoring Program - JOVA. I am Head of Department for Pesticides and natural products chemistry at NIBIO since 2014.

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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.

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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.

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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.

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Abstract

This project evaluated whether the principles of combined toxicity assessment (CTA) and cumulative risk assessment (CRA) can be used to predict the toxicity of ecologically-relevant mixtures of plant protection products (PPPs) in surface waters receiving run-off from Norwegian agricultural areas. A combination of testing solid phase extracts (SPE), whole surface water and a synthetic mixture in an algal bioassay and predicting combined toxicity using CTA models were conducted on selected samples from the Heia catchment (Råde, Norway). The results demonstrated that designing and testing synthetic mixtures on the basis of measured concentrations of PPPs was the best method for the accurate determination of combined toxicity due to confounding factors introduced by whole water and SPE testing. Combined toxicity models based on Concentration Addition (CA) successfully predicted the toxicity of the complex synthetic mixture and verified that a mixture of PPPs acted in an additive manner. Tiered assessment of the cumulative risk of active PPP substances and PPP formulations proposed by the European Food Safety Authority (EFSA) were considered applicable also for the CRA of complex environmental mixtures and could potentially aid the identification of relevant mixtures, risk drivers and susceptible species as input to the assessment and approval of PPPs.

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Abstract

This project was performed to improve the environmental cumulative risk assessment (CRA) of mixtures of plant protection products detected by the Norwegian Agricultural Environmental Monitoring Programme (JOVA) in Norwegian surface waters. Existing ecotoxicity data were compiled and reduced the assessment uncertainty compared to previous risk assessments. Ecotoxicity tests verified that the cumulative toxicity of ecologically-relevant environmental mixtures was fairly well predicted for algae, daphnia and aquatic plants. The results from the ecotoxicity tests were used to evaluate the assessment factor used in the risk assessment, and the improved data used in the CRA of plant protection products in the JOVA monitoring performed in 2013. Three of the six investigated sites had risk quotients indicative of environmental risk. Mitigation measures based on the identification of the main risk drivers were discussed and include consideration of no-spray zones, grassed buffer strips, reduced doses and patch spraying, and pesticide risk maps.

Abstract

In Europe there is an on-going process on implementing regulations aimed at reducing pollution from agricultural production systems, i.e. the Water Framework Directive and the Framework Directive for Sustainable Use of Pesticides. At the same time, there is an increasing focus on food security possibly leading to continued intensification of agricultural production with increased use of external inputs, such as pesticides and fertilizers. Application of sustainable production systems can only be achieved if they balance conflicting environmental and economic effects. In Norway, cereal production is of large importance for food security and reduction of soil and phosphorus losses, as well as pesticide use and leaching/runoff in the cereal production are of special concern. Therefore, we need to determine the most sustainable and effective strategies to reduce loss of top soil, phosphorus and pesticides while maintaining cereal yields. A three-year research project, STRAPP, is addressing these concerns. A catchment area dominated by cereal production is our common research arena within STRAPP. Since 1992 a database (JOVA) with data for soil erosion, nutrient and pesticide leaching/runoff (i.e. concentrations in stream water), yield, and agricultural management practices (fertilization, use of pesticides, soil tillage and rotations) has been established for this catchment allowing us to compare a unique diversity in cropping strategies in a defined location. An important part of STRAPP focuses on developing ‘best plant protection strategies’ for cereal fields in the study area, based on field inventories (manual and sensor based) of weeds and common diseases, available forecast systems, and pesticide leaching risk maps. The results of field studies during the growing seasons of 2013 and 2014 will be presented, with a focus on possible integrated pest management (IPM) strategies for weeds and fungal diseases in cereal production. We will also present the project concept and methods for coupling optimized plant protection strategies to (i) modelling of phosphorus and pesticide leaching/runoff, as well as soil loss, and (ii) farm-economic impacts and adaptations. Further, methods for balancing the conflicting environmental and economic effects of the above practices, and the evaluation of instruments for increased adoption of desirable management practices will be outlined.

Abstract

Effective pest management is a prerequisite to maintain yields of sufficient quality and quantitywithin agriculture. In conventional agriculture this involves the use of pesticides, and current legislation focus on the need for increased awareness of the environmental consequences and a sustainable use. The Norwegian Agricultural Environmental Monitoring Program (JOVA) aims at documenting environmental consequences of both the current agricultural practices and changes with time,due to changes imposed by policy, laws and regulations, climatic factors a.o., and include collection of pesticide use data within selected agricultural catchments. The catchment scale data on plant protection practices from the JOVA-program indicate reduced use of pesticides in the catchments dominated by potatoes and vegetables, and meadows and pasture, while there are no indications of reduced use of pesticides in cereal production. There have been marked shifts in the pesticide use within the catchments during the monitoring period due to changes in management practices and the continuous change in the range of pesticides available for control of a certain pest. The monitoring of pesticide residues in surface and ground waters in the JOVA-catchments depend on analyses that do not include all important pesticides in use. Hence, the environmental challenges connected to the current pesticide use in Norwegian agriculture are not fully explored. This is particularly of concern regarding the widespread use of glyphosate and sulfonylurea herbicides for weed control, as well as the rapidly increasing use of prothioconazole to control Fusarium spp. in cereal. The long-term, farm scale pesticide use data from the JOVA-program is a unique source ofinformation to establish the necessary knowledge to design measures and instruments to reduce pesticide pollution from agriculture, and should be utilized in the future use of pesticide risk indicator models that is recommended through the Framework Directive for Sustainable Use of Pesticides.

Abstract

Chemical pesticides should disappear rapidly after achieving its intended effect, leaving the environment free from harmful residual amounts. Due to the complex interactions between the processes affecting the fate of pesticides and various environmental factors, pesticides and metabolites might persist and be transported in the environment. The Norwegian Agricultural Environmental Monitoring Program (JOVA) aims at documenting the environmental consequences of current agricultural practices and changes in these practices with time, and includes monitoring of possible occurrence ofpesticide residues in streams and rivers in selected agricultural catchments. Sixteenyears of pesticide monitoring within the JOVA-catchments shows considerablevariation in retrieval of pesticide residues in water with time, and demonstrate the need for long-term time series as a reference to enable evaluation of single-year results. On average two pesticides are detected in each sample analysed, but there are large variations between the different catchments. The overall trends emerging from the monitoring data for the period 1995-2010 include (1) reduced environmental load from pesticides in potato and vegetable production, (2) increased use and detections of fungicides in cereal, (3) low concentrations of pesticides detected in areas with meadows and pasture, and (4) detections of pesticides in large rivers. The validity ofthese results is limited by the restrictions in the pesticides analysed compared to the pesticides in use, as well as other methodological and analytical restrictions, and the problems with pesticides in surface and ground waters of Norwegian agricultural catchments are not yet fully explored. The implementation of new European regulations within the fields of water management, in general, and sustainable use of pesticides, in particular, demands continuous monitoring to document their effects. To fulfill theserequirements the pesticide monitoring in JOVA can be expected to have continuedand increased value in the years to come.

Abstract

Current risk assessment procedures for contaminated land and for pesticides often fail to properly characterize the risk of chemicals for environment or human health and provide only a rough estimate of the potential risk of chemicals. Chemicals often occur in mixtures in the environment, while regulatory agencies often use a chemical-by-chemical approach, focusing on a single media, a single source, and a single toxic endpoint. Further, the importance of soil microbes and their activity in the functioning of soils impose a need to include microorganisms in soil quality assessments including terrestrial ecotoxicological studies. Numerous papers have been published on the effects of different contaminants on soil microbes, establishing changes in soil microbial diversity as an indicator of soil pollution. However, only a limited number of molecular studies focus on changes in fungal species when investigating soil microbial diversity. The main objective of the study presented here, is to assess the applicability of changes in soil microbial diversity and activity levels as indicators of ecologically relevant effects of chemicals contamination. We will achieve this through studies of effects of the fungicide picoxystrobin and the chemical 4-n-nonylphenol on the microbial biodiversity in a Norwegian sandy loam, with focus both on prokaryotes and the fungal species. Laboratory incubation experiments at 20°C with soil samples treated with the single chemicals or mixtures, with continuous monitoring of respiration activity as well as occasional destructive sampling for extraction of soil DNA, RNA, and chemical residues, was performed through a 70 d period. Results from amplification of soil bacterial and fungal DNA followed by T-RFLP (terminal restriction fragment length) analyses to assess chemicals effects on soil microbial diversity, indicate significant effects of the studied chemicals on soil microbial community structure. To identify specific bacterial or fungal groups that are affected, an assessment of the effects of the chemicals on the soil microbial metagenome by high throughput shot-gun sequencing (454 sequencing) is in progress This work is part of the research project ‘Bioavailability and biological effects of chemicals - Novel tools in risk assessment of mixtures in agricultural and contaminated soils’ funded by the Norwegian research council.

Abstract

Introduction: Current risk assessment procedures for contaminated land and for pesticides often fail to properly characterize the risk of chemicals for environment or human health and provide only a rough estimate of the potential risk of chemicals. Chemicals often occur in mixtures in the environment, while regulatory agencies often use a chemical-by-chemical approach, focusing on a single media, a single source, and a single toxic endpoint. Current concepts to estimate biological effects of chemical mixtures mainly rely on data available for single chemicals, disregarding interaction between chemicals in soils. The importance of soil microbes and their activity in the functioning of soils impose a need to include microorganisms in soil quality assessments (Winding et al., 2005) including terrestrial ecotoxicological studies. Numerous papers have been published on the effects of different contaminants on soil microbes, establishing changes in soil microbial diversity as an indicator of soil pollution, but only a limited number of molecular studies investigating fungal diversity in the environment have been performed. The main objective of the study presented here, is to assess the applicability of changes in soil microbial diversity and activity levels as indicators of ecologically relevant effects of chemicals contamination. We have studied the effects of the fungicide picoxystrobin and the chemical 4-n-nonylphenol, on the microbial biodiversity in a Norwegian sandy loam with focus both on prokaryotes and the fungal species. 4-n-nonylphenol is a chemical occurring in high amounts in sewage sludge, hence, these chemicals may occur as single chemicals as well as in mixtures in soils. This work is part of the research project ‘Bioavailability and biological effects of chemicals - Novel tools in risk assessment of mixtures in agricultural and contaminated soils" funded by the Norwegian research council.Methods: Soil samples were treated with the single chemicals or mixtures and incubated at 20°C. Continuous monitoring of respiration activity as well as occasional destructive sampling for extraction of soil DNA, RNA, and chemical residues was performed through a 70 d period. Amplification of soil bacterial and fungal DNA was followed by T-RFLP analysis to assess chemicals effects on soil microbial diversity. Further work will include analyses of extracted soil RNA to assess chemicals effects on important soil functions (e.g. nitrogen cycling, decomposition of organic matter) and an assessment of chemicals effects on the genetic diversity of the soil by high throughput shot-gun sequencing. Finally the results will be evaluated to assess the suitability of any specific group, species or activity/function as biomarker for the selected chemicals (and possibly their group of chemicals).Results and conclusions: A project outline and preliminary results from the project will be presented at the conference.ReferencesWinding A, Hund-Rinke K, Rutgers M (2005). The use of microorganisms in ecological soil classification and assessment concepts. Ecotoxicology and Environmental Safety 62: 230-248.