Ecological conditions, including biodiversity, are under constant pressure in a number of aquatic areas, such as lakes, streams and fjords, due to increased input of nutrients, environmentally hazardous substances etc. from urban communities and agriculture, global climate change and other human activities. We conduct research to acquire new knowledge and insight into how best to respond to the negative consequences, and on this basis we also provide consultancy to various authorities, both nationally and internationally. In this way, we help to ensure that the management of our aquatic areas is based on the latest research. We are also actively involved in the education of new biologists and agroecologists at Bachelor, Master and PhD level at Aarhus University as well as at the Sino-Danish University in Beijing.
Our research and consultancy activities can be divided into four core areas:
Through participation in the national environmental and nature monitoring programme NOVANA, we monitor the use and handling by agriculture of nutrients and their fate. We are, among other things, responsible for determining how agriculture implements the adopted tools to reduce the loss of nutrients to the aquatic areas. In addition, we are responsible for the annual reporting of the runoff of nitrogen and phosphorus to the sea around Denmark. In our research, we use both simple and advanced models to describe and understand biogeochemical processes in stream catchment areas, including the effect of climate changes. The knowledge gained from monitoring and research is widely used in consultancy services to the authorities.
Diffuse nutrient loss is difficult to control due to the many factors such as climate, geological conditions and land use that affect the loss. The most cost-effective reduction of nutrient loss is achieved through targeted mitigation measures. We develop and test different types of tools that are subsequently applied in, among others, the national river basin management plans. Examples of tools are controlled drainage, buffer zones, integrated buffer zones, saturated buffer zones, constructed wetlands with open water surfaces and constructed wetlands with matrices of various materials.
The adoption of the Aquatic Environment Plan II in 1998 was also the start of a series of restoration plans for mainly freshwater wetlands, which have been continued until today – most recently with the decision on taking large organic low-lying areas out of agricultural production. Research into environmental and climate conditions in wetlands combined with a description of the hydrological processes that take place in interaction with the biogeochemical processes are key elements of our work. We are also comparing the pre-and post-situation in connection with restoration of wetlands and investigating how we can avoid adverse side effects by using measures such as the establishment of temporary phosphorus filters and biomass harvesting. Since 2010, we have been working to develop and design constructed wetlands targeted at the removal of nutrients in drainage water – these are are better known as mini-wetlands with open water surface and mini-wetlands with matrix.
We have many kilometres of streams in Denmark, and depending on how it is calculated, the figure ranges between 30,000 and 60,000 km. The streams interact closely with the surrounding landscape, and they are therefore particularly vulnerable to human activities in their immediate surroundings, which contribute to changing both nutrient conditions and hydromorphological conditions. Most Danish streams have been straightened and deepened, and frequent weed cuttings have significant impacts on the aquatic plants and animals and thus also on the ecological state assessed according to the Water Framework Directive. Our research addresses both basic scientific and application-oriented questions and is often conducted in close collaboration with the Department of Biology at AU as well as other national and international research institutions, with a particular focus on also elucidating the role of streams in the green transition, and how various tools can contribute to this.