Characterising the nature, origins and impact of dissolved organic matter in freshwater ecosystems

From toxic algal blooms to the mobilisation of pollutants, could understanding the complexities of dissolved organic matter help society tackle environmental decline?

The challenge

Dissolved organic matter (DOM) plays a pivotal role in aquatic biogeochemistry delivering vast quantities of organic carbon, nitrogen and phosphorus to freshwater ecosystems. In Europe the control of nutrient flux to all freshwaters and the coastal zone is required to meet the target of restoring waters to Good Ecological Status under the EU Water Framework Directive. Routine water quality monitoring is largely based on inorganic nutrient fractions, and substantially underestimates the total nutrient flux to waters. While research confirms that DOM plays an important role in ecosystem function including supporting microbial metabolism, primary production and pollutant transport, its oversight in routine monitoring may undermine international efforts to bring nutrient enrichment impacts under control.

Nutrient enrichment of freshwaters has far reaching consequences including toxic algal blooms, eutrophication and oxygen depletion, with increasing organic nitrogen and carbon also linked to carcinogen formation during drinking water treatment. The UN has listed coastal nutrient pollution and hypoxia as the one of the greatest current threats to the global environment.

A detailed understanding of the nature, origins and rates of nutrient delivery to waters is essential if we are to control these impacts through management intervention, yet much of the necessary evidence base is currently lacking.

What we’re doing

The NERC-DOMAINE project is addressing this knowledge gap by undertaking a suite of interlinked experimental and observational research from molecular to catchment scale. We are using a range of cutting-edge approaches which are novel in their application to nutrient cycling research. The DOMAINE project is delivering improved understanding of:

  • The role of DOM in the transport of nitrogen and phosphorus from source to sea and the ways in which this might alter nutrient delivery to freshwaters.
  • The ecological significance of DOM as a source of nutrient uptake and utilisation by algal, plant and microbial communities.
  • The impacts of DOM flux from soils, livestock and human waste fluxes on the ecological status, goods and services provided by freshwaters.

How it helps

Improving our understanding of the ecological significance of DOM to nutrient cycling will enable policy makers to make more effective decisions to reduce the detrimental impacts that increasing nutrient fluxes have on our freshwater ecosystems.

Lead researcher profile

Penny Johnes, Professor of Biogeochemistry


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