Conceptual, mathematical and simulation models are important and exciting, because they capture general principles of a scientific area and because they can make
predictions.This website is about the development of ecotoxicological models, the research focus of my
Thank you for visiting,
Pesticide avoidance behaviour of non-target arthropods and its population level consequences in spatially heterogeneous exposure landscapes
(BBSRC Industrial CASE studentship)
Project description: Non-target arthropods (NTAs) provide important ecosystem services (e.g. control of pests). However in agricultural systems some beneficial arthropods may be at risk from the pesticides used to control insects that damage crops. Predicting the risk to NTAs is complicated by the non-uniform distribution of pesticides in and around crops. In this PhD you will:
The results of the PhD will feed into regulatory risk assessment of pesticides for the protection of non-target organisms.
Host institution & supervisors: The PhD student will be based at the Environment Department at the University of York (UoY) and the project will be led by Roman Ashauer (main supervisor) and Prof Mark Hodson (co-supervisor).The Environment Department has a reputation for excellence and innovation; the impact of our research in ecology and environmental science is ranked 2nd in the UK and 17th globally. The environmental fate and effects of pollutants is a core area of research.
Industry & government agency partners: The PhD student will spend at least three months in placements at the project partners, who are Dr Gabe Weyman at Makhteshim Agan (industry, senior regulatory ecotoxicologist), Dr Tania Alvarez at EcoRisk Solutions (arthropod ecology & ecotoxicology) and Dr Melissa Reed at the Chemicals Regulation Directorate (pesticide environmental risk assessment & ecological modelling).
Training provided in: regulatory pesticide risk assessment, ecotoxicology, analytical chemistry, NTA ecology, ecological modelling, field & laboratory studies and advanced generic & transferable skills.
Start date & duration: The project will start 1 October 2014 and last four years.
Funding & eligibility: The studentship will cover a stipend of approximately 15,700 GBP per year (incl. industry supplement). Applicants must have obtained, or be about to obtain, a First or Upper Second Class UK Honours degree, or the equivalent qualifications gained outside the UK in an appropriate area of science or technology. Applicants must be a UK candidate or an EU candidate who has resided in the UK for at least 3 years by 30 Sep 2014 if starting the PhD on 1 Oct 2014.
Application: Please include a CV, the names and addresses of two academic referees and a covering letter. In the covering letter (max. 1 side A4) please describe any experience and skills you feel make you a suitable candidate for the position and why you are interested in the project. Please email your application to firstname.lastname@example.org. Application remains open until the position is filled.
More information about us: www.york.ac.uk/environment
I'm very happy to announce that we will be offering the summer school "Dynamic modelling of toxic effects" in August 2014. This time the focus will be on DEBtox and, as before it will take place
in Denmark (from 5 to 13 August 2014). Please book soon, because I have a feeling that there is a lot of interest. Link
to course website.
Abstract: Exposure and depuration experiments for Gammarus pulex and Daphnia magna were conducted to quantitatively analyze biotransformation products (BTPs) of organic micropollutants (tramadol, irgarol, and terbutryn). Quantification for BTPs without available standards was performed using an estimation method based on physicochemical properties. Time-series of internal concentrations of micropollutants and BTPs were used to estimate the toxicokinetic rates describing uptake, elimination, and biotransformation processes. Bioaccumulation factors (BAF) for the parents and retention potential factors (RPF), representing the ratio of the internal amount of BTPs to the parent at steady state, were calculated. Nonlinear correlation of excretion rates with hydrophobicity indicates that BTPs with lower hydrophobicity are not always excreted faster than the parent compound. For irgarol, G.pulex showed comparable elimination, but greater uptake and BAF/RPF values than D.magna. Further, G. pulex had a whole set of secondary transformations that D. magna lacked. Tramadol was transformed more and faster than irgarol and there were large differences in toxicokinetic rates for the structurally similar compounds irgarol and terbutryn. Thus, predictability of toxicokinetics across species and compounds needs to consider biotransformation and may be more challenging than previously thought because we found large differences in closely related species and similar chemical structures.
Published in Environmental Science & Technology (link to paper at ES&T).
Abstract: Organisms in the environment experience fluctuating, pulsed, or intermittent exposure to pollutants. Accounting for effects of such exposures is an important challenge for environmental risk assessment, particularly given the simplified design of standard ecotoxicity tests. Dynamic simulation using toxicokinetic-toxicodynamic (TK-TD) models describes the processes that link exposure with effects in an organism and provides a basis for extrapolation to a range of exposure scenarios. In so doing, TK-TD modeling makes the risk assessment more robust and aids use and interpretation of experimental data. Toxicokinetic-toxicodynamic models are well-developed for predicting survival of individual organisms and are increasingly applied to sublethal endpoints. In the latter case particularly, linkage to individual-based models (IBMs) allows extrapolation to population level as well as accounting for differences in effects of toxicant exposure at different stages in the life cycle. Extrapolation between species remains an important constraint because there is currently no systematic understanding of species traits that cause differences in the relevant processes. Toxicokinetic-toxicodynamic models allow interrogation of exposure profiles to determine intrinsic toxicity potential rather than using absolute maximum concentrations or time-weighted averages as surrogates. A decision scheme is proposed to guide selection of risk assessment approaches using dose extrapolation based on Haber's Law, TK-TD models, and/or IBMs depending on the nature of toxic effect and timing in relation to life history.
Published in Integrated Environmental Assessment and Management (link to paper at IEAM).