Catchnet Research package 3

The Catchnet Research package 3 concerns biogeochemical processes and investigates elemental transport under dry and cold climates and its relevance for nuclear safety.

One key component when making risk assessments concerning deep repositories for spent nuclear waste is knowledge on how elements and compounds are transported through the environment. During a previous project in Greenland run by SKB, the GRASP-project, we gained considerable knowledge on how the dry and frozen conditions in the Two-Boat Lake catchment, West Greenland, affect the elemental transport. In brief: i) running water is confined to the few wetland areas and there is a limited hydrological transport of both particles and solutes from upland soils to the aquatic system. Therefore there is a potential for buildup of both weathering products and elements supplied via wet deposition in upland soils, ii) because of the limited outflow from the lake many elements will – over time – become concentrated in the lake water, and iii) eolian transport can play an important role for the supply of certain elements under dry conditions with limited surface water runoff.

To take this knowledge further, there is a need to put Two-Boat Lake into a larger context by comparing the dry and frozen landscape of West Greenland to other climate settings. For example, how would the biogeochemical cycling at Two-Boat Lake change under a warmer climate when the permafrost disappears, or how would the transport of elements change at a temperate site (e.g., Forsmark in Sweden) if the soils become permanently frozen?

Aim of Research

The overarching aim of the CatchNet Research package 3 (RP3) is to gain knowledge on how climate – primarily temperature and effective precipitation – affect the biogeochemical cycling of various elements. To achieve this, we will study elemental cycling across a climate gradient to obtain an even deeper understanding on the elemental transport under various climate conditions. This understanding can then help us to predict, for example, whether a specific landscape compartment would switch from being a sink to a source when the climate is altered.

Research focus

RP3 will focus on understanding how differences in climate, hydrology and vegetation affect the relative importance between different biogeochemical processes (e.g., eolian transport, hydrological transport, release from soils, and accumulation in soils and sediments). This will be achieved by studying elements with different biogeochemical behavior – e.g., those that are part of mineral grains, released through weathering, or that are mainly supplied with rain and snow – across a climate gradient. The gradient used will include Two-Boat Lake and Forsmark – the planned site for building a deep geological repository for spent nuclear fuel in Sweden– where biogeochemical and hydrological data have been gathered by SKB over a long time period. To better link the cold-temperate climate of Forsmark with the low-arctic climate of Two-Boat Lake additional site will be included in the climate gradient, e.g., the boreal Krycklan catchment in north-central Sweden and Wolf Creek in Canada. Working with a climate gradient spanning from arctic to cold-temperate regions will provide us with the opportunity to understand how differences in temperature and precipitation affect, e.g., where in the landscape a released radionuclide is most likely to end up, and whether it will be concentrated or diluted over time.

More specific research questions could include, e.g.:

• How does temperature and precipitation affect the transport of slow-weathering elements (e.g., Al and Ti), fast-weathering elements (e.g., Ca and K), easily dissolved, non-reactive, elements (e.g., Cl), reactive nutrients (e.g., N and P), and organically bound element (e.g., C)?
• Are there any differences in the seasonal variability due to differences in the climate?
• Is temperature or precipitation the most important driver for any biogeochemical differences between climate settings?
• What is the influence of non-steady state situations on biogeochemical cycling under different climate conditions?

Team

Sean Carey. Dr. Sean Carey is a Professor in the School of Geography and Earth Sciences at McMaster University in Canada where he directs the Watershed Hydrology Group. His research interests include hydrological and land surface processes in natural and human impacted environments. He has a particularly enthusiasm for cold environments and has been working in subarctic Yukon for the past 25 years.

Johan Rydberg. Dr. Johan Rydberg work at the Department of Ecology and Environmental Science, Umeå University. He works primarily with how different perturbations – natural or human induced – have affected the biogeochemical cycling over long time scales (decades to millennia) using natural archives such as lake sediments and peat deposits. Johan Rydberg has been involved in the biogeochemical aspects of the GRASP-project, and will continue to work on how the biogeochemical cycling of elements is affected by, e.g., climate, hydrology and vegetation within the CatchNet-project.