Department of Earth and Atmospheric Sciences

White and his group are interested in processes controlling the cycling of elements in aquatic and terrestrial systems and in the potential impact of human activity on element cycles. They study cycling of elements in freshwater ecosystems, wetlands and terrestrial soils from temperate agricultural landscapes to remote Arctic ecosystems. Their tools range from stable isotopes to high-throughput genomics.

The research focuses on understanding human impacts on feedbacks of environmental systems, particularly aquatic and terrestrial ecosystems. Since 1990, the group has been studying greenhouse gas emissions in northern landscapes under changing climate. Current research includes a NASA-funded project investigating greenhouse gas cycling in lakes, wetlands and soils at the edge of the Greenland Ice Sheet. The role of local climate (temperature, insolation, and water level) in controlling methane budgets of northern landscapes is studied using chemical mass balances, stable isotopic analyses, genomic sequencing of soil microbial communities, and continuous records of climatic variables. The results are used to refine mechanistic models that describe methane cycling in detail and which will allow prediction of responses of natural rates of methane production to climatic change. They are also working in Alaska on the role of fungi in affecting plant community responses to permafrost thaw in the sub-Arctic.

Other areas of research include: the development of stable isotopes of nitrogen as a "fingerprinting" tool to identify the sources of ammonia and nitrate in surface water; improvement of sampling and analysis techniques for trace metals in gravel sediments; and development of new isolation techniques for microbial communities inhabiting wetland sediments.