The Department of Hydrochemistry and Ecosystem Modelling (HEM) of the Institute of Hydrobiology of the Biology Centre AS CR studies biogeochemical cycles and processes that control composition and quality of surface waters. This interdisciplinary research is focused on the structure, functions, problems and management of aquatic environments like reservoirs, natural lakes and their catchments.

The staff also provide lecturing of aquatic and environment sciences at the University of South Bohemia and are engaged in advisory services on water quality and aquatic ecosystem functioning for water policy and water management.

The main subjects of studies include:

• processes of acidification of the mountain lakes and their catchments;
• eutrophication of water ecosystems as a result of external and internal nutrient loading;
• reconstruction and modelling of historical trends in biogeochemical cycling of the macronutrients in aquatic ecosystems;
• photochemical processes involved in the transport of macro- and micronutrients via dissolved organic matter from soils to aquatic systems;
• the role of sediments and organic matter in the internal cycling of nutrients in lakes;
• the environmental characteristics which can best explain the patterns of nutrient flux to waters in complex catchments.