QUANTOM

Norwegian Research Council (FRIPRO) 2021-2024

1. Popular account

QUANTification of dissolved Organic Matter and the metabolic balance in river networks: mechanisms and model simulations of CO2 emissions

We want to discover how land and rivers are connected to better understand the global carbon cycle and river food webs north of the Arctic circle. Rivers are the 'blood vessels' draining the 'body of the Earth’ and export vast amount of carbon to the sea and the atmosphere. A large fraction of this carbon is from dissolved organic matter leaching out of soils and giving the water a yellow brown colour. On its journey to the sea, bacteria on the riverbed use oxygen to transform this terrestrial carbon into CO2. The increase in bacterial activities may suppress the growth of green algae by competing for limiting nutrients, thus changing the metabolic balance between photosynthesis and respiration (increasing CO2 emissions) and the quality of the food available for consumers.

We will take the daily and annual oxygen pulses of rivers using in-situ sensors. We want to discover how these pulses are intimately related to daily and seasonal land vegetation growth using satellite imageries from the European Space Agency and NASA. We will characterise the diversity and composition of the 10,000+ organic molecules and follow their transformation across interfaces and size of streams under different hydrological conditions throughout the growing season. We will link these molecular transformations (microcosm) to river metabolism (macrocosm).

We will build a mathematical model to represent, in the most parsimonious way, our understanding of carbon processes in large northern latitude river basins with heterogeneous landscape (rocks, tundra, pine and birch forest and peat plateau with discontinuous permafrost - frozen mounts thawing rapidly with warming). We will use the River Tana (Norway) flowing north of the arctic circle as a model river basin to collect data and run scenarios of climate and land use change. We will also test the effects of dissolved organic matter, nutrients and temperature on the metabolic balance and food webs using whole stream and lab experiments.

2. Team

The project involves five research organisations with complementary skills

2.1. Norwegian water research institute (NIVA)

Benoît Demars will lead this project to integrate land to water processes, molecules to landscapes, in order to better understand carbon cycling at the soil water interface and along rivers. Within the consortium, He will bring and share his expertise in large scale field survey, stream and chamber metabolism, whole stream nutrient manipulation and food web. He has an interest in using stoichiometry and metabolic theory to make quantitative predictions on how dissolved organic matter may be processed. He also have an interest to develop equations for in-stream metabolism at river network scale for the integrated catchment model.

Odd-Arne Skogan (NIVA Instrument section) is interested in programming, sensor data logging, environmental sensors and high-tech measuring technology. From previous work and projects he has a lot of experience from setting up and preparing various data logger stations for use in the field connected to a variety of sensors.

Maeve McGovern is interested in linking the quality and quantity of organic matter inputs to in-stream processes, and how these inputs and processes intersect and evolve seasonally and spatially along the terrestrial-aquatic-marine continuum. Within Quantom, Maeve will carry out bottle incubations to determine DOM degradation rates for OM sources across a gradient in land-cover types. In addition to DOC loss, she will investigate how molecular and optical characteristics of DOM of various sources are transformed by photochemical and microbial processing. Carried out across the entire Tana catchment from headwaters to the fjord, these incubations will characterise within-system pelagic processes as well as target cross-ecosystem (land-river, river-fjord) resource transport and utilization. In addition, this work will provide context for broader spatial sampling of ‘snapshot’ DOM optical and molecular characteristics for a broader understanding of how ecosystem control points impact downstream OM reactivity in space and time.

Leah Jackson-Blake is interested in all aspects of catchment hydrology and nutrient cycling, in particular in sensitive Arctic regions which are particularly at risk from climate change. She has a strong background in the development, application and assessment of process-based models, with a focus on developing parsimonious models which are able to produce robust predictions, and she will be bringing this expertise to lead the carbon model development. In addition, she has substantial experience in field monitoring campaigns and empirical data analysis, which will allow me to both support work in the other WPs, and ensure they produce data which is suitable to inform model development.

James Sample focuses his research on the spatio-temporal modelling of surface and groundwater hydrology and geochemistry, with particular emphasis on relationships between land use, climate change and water resources. He is especially interested in issues of scale, complexity and uncertainty in environmental modelling, and in statistical approaches for robust model evaluation.

Magnus Norling is developing better catchment models, along with software frameworks to support, validate and compare such models. His expertise comes from mathematical modeling, analysis of dynamical systems, and programming.

2.2 Norwegian Research Centre AS (NORCE), Climate and Environment

Stein Rune Karlsen interest is to support this project with mapping products of the terrestrial vegetation. He is a plant ecologist with 20+ years of field experience from the Tana River basin study area, where he has been working with mapping of seasonal changes (phenology), vegetation mapping, and mapping of leaf defoliation and changes in understory vegetation of birch forest due to insect attacks. Together with Kjell Arild Høgda and his Earth Observation group he will contribute to the project with satellite-based mapping products of these topics.

Kjell Arild Høgda interest is to support the project with satellite remote sensing technology and products.  He has for 30+ years worked with and managed projects within a broad spectrum of satellite remote sensing applications including pollution and insect impact studies, satellite data time series analysis for phenology, and climate change impacts studies. In this project he will, in cooperation with Stein Rune Karlsen, work with time series analysis of available satellite data for seasonal changes (phenology), annual productivity and effect on vegetation of insect attacks.

2.3. Norwegian University of Life Sciences (NMBU)

Peter Dörsch has a general interest in biogeochemistry and land-water coupling from a perspective of global and local climate change and biosphere-atmosphere interactions. His recent research focus includes permafrost thawing in the Subarctic. Peter will be co-designing and hosting the laboratory experiments.

2.4. The James Hutton Institute (JHI, UK)

Marc Stutter is a senior soil and water biogeochemist with interests in the coupled cycling of C, N and P in soils, passage to the stream and in river channels. This includes joint working with Benoit Demars on aspects of this which will be built upon in terms of concepts, experimental methods and analytical techniques.

Barry Thornton has an interest in application of stable isotopes in understanding the fluxes of carbon in a wide range of ecosystems (terrestrial, riverine and marine). He will bring his expertise in application, analysis and interpretation of carbon isotopes; both bulk and compound specific (i.e. phospholipid fatty acids).

2.5. Louisiana Universities Marine Consortium (USA)

Juliana D’Andrilli interests will support the project to better understand carbon cycling from the perspective of dissolved organic matter (DOM) characterization. Specifically, analytical chemistry instruments and analyses will be used to identify DOM composition changes with production, transformation, and storage in freshwater and marine ecosystems. She will bring and share her expertise on DOM qualitative analyses using multiple techniques to broaden our understanding of stream and chamber metabolism when DOM (i.e. energy sources) fluctuate with riverine inputs. She is interested in using molecular level compositions to identify markers that can help predict biological, physical, and chemical processes linked to carbon dioxide outgassing and long-term storage. DOM reactivity in the environment is an extremely important component to understand once materials are mobilized and/or exposed to different variables and no one technique can definitively measure it alone; a suite of complementary techniques must be used. Her interests extend to using analytical chemistry techniques that combine data from field samples, biological incubations, and model predictions to extend what can be gained from chemical analyses.

3. Sampling design

We have chosen a nested approach where sub-cachments with contrasting land cover were selected for process based measurements, in addition to carbon flux determination for the main stems and outlet of River Tana.