Dr Sylvia Toet
Honorary Fellow

Research

Overview

Previous research activity

2007-2008	UKPopNet	University of York	Linking microbial biodiversity and trace gas fluxes at the landscape scale: the Bug-to-Big project
2004-2007	NERC	University of York	Tropospheric ozone pollution: using stable isotopes to quantify ozone deposition, uptake and detoxification
2000-2004	USF grant 98.24	Vrije Universiteit Amsterdam	CH4 and CO2 fluxes in peatlands: role of plants and responses to global change
1995-2000	PhD	Utrecht University	A treatment wetland polishing effluent from a sewage treatment plant: performance and processes

Projects

Unravelling the effects of elevated tropospheric ozone on CH₄ and CO2 fluxes through below-ground processes

(NERC, University of York, 2008-2010)

Tropospheric ozone is the most important gaseous air pollutant globally in terms of effects on ecosystem production and function, and is currently the third most important contributor to the human-induced greenhouse effect. Increases in northern hemisphere background ozone concentrations are predicted over this century, and the potential for ozone to reduce carbon assimilation is well known. However, there is little understanding of its effects on both CH₄ and CO₂ fluxes and the underlying processes. The potential importance of ozone in reducing carbon (C) assimilation, and consequently in increasing atmospheric CO₂ concentrations, has been recognised. Recent modelling studies suggest that ozone may have significant long-term effects on C budgets. However, such models are based only on ozone effects on rates of photosynthesis and assimilate partitioning, and lack any representation of effects of ozone on below-ground processes. Furthermore, almost all existing studies on the impacts of ozone on below-ground C fluxes have been carried out in forest or arable crop systems. Large soil organic C pools are present in northern hemisphere peatlands and grasslands, and these ecosystems, along with forests and arable land, were the most significant contributors to the net terrestrial C balance of Europe during the 1990s. Furthermore, peatlands are a significant global source of CH₄, but few studies have assessed ozone effects on CH₄ fluxes.

The aim of this study is to significantly increase understanding of the effects of elevated ozone on key processes below-ground and hence on net CH4 and CO2 fluxes in peatlands and grasslands. This will be achieved by experiments in open-top chambers (Close House field station, Newcastle University; Prof. Jeremy Barnes) with the application of new techniques using stable isotopes and molecular techniques to understand effects of elevated ozone on below-ground carbon flows, and microbial activity and community structure. Prof. Ineson and Dr. Thorunn Helgason are also involved in this project.

External activities

Invited talks and conferences

Can small-scale controlled experiments predict the impacts of landscape scale management changes? (2009) UKPopNet/RSPB Knowledge exchange meeting on Lake Vyrnwy research, Shrewsbury, UK.

Effects of elevated ozone on methane and carbon dioxide fluxes from peatland mesocosms (2009). British Ecological Society Annual Meeting, Hatfield, UK.

Chemical ozone reaction on leaf surfaces identified using a novel stable isotope approach (2009). Committee on Air Pollution Effects Research Annual Meeting meeting, Manchester, UK.

Linking microbial biodiversity and trace gas fluxes at the landscape scale: the bug-to-big project (2008). UKPopNet 4th Annual Conference, York, UK.

Effects of ozone on soil and plant processes in a raised bog (2006). British Ecological Society Annual Meeting, Oxford, UK.

A novel stable isotopic approach to identify the fate of ozone in plants (2006). 5th International Conference on Applications of Stable Isotope Techniques to Ecological Studies, Belfast , UK.

¹⁸O tracer studies to identify the fate of ozone in plants (2006). Committee on Air Pollution Effects Research Annual Meeting, Edinburgh, UK.

A ¹³C tracer study to quantify the contribution of Carex rostrata litter to methane emitted from a temperate peatland (2004). Annual symposium of the Institute of Ecological Research, Vrije Universiteit, Amsterdam, The Netherlands.

¹³C tracer studies to quantify the contribution of recent photosynthates and plant litter to methane emitted from peatlands (2002). BASIN conference 'Stable isotopes and biosphere-atmosphere interactions', Banff, Canada (poster).

Effects of a wetland system on the quality of effluent from a sewage treatment plant (1999). Workshop 'Nutrient cycling and retention in wetlands and their use for wastewater treatment', Trebon, Czech Republic.

Denitrification in soil, periphyton and water of a surface-flow wetland system used for polishing tertiary wastewater (1998). 6th International conference on wetland systems for water pollution control, Aguas de Sao Pedro, Brazil.

A constructed wetland system to improve the effluent quality from an oxidation ditch II (1998). 6th International conference on wetland systems for water pollution control, Aguas de Sao Pedro, Brazil (poster).

Periphyton biomass and nutrient uptake in Phragmites and Typha stands used for polishing sewage plant effluent (1997). Symposium 'Eutrophication research: state-of-the-art', Wageningen , The Netherlands (poster).