Dissolved organic matter (DOM) plays a fundamental role in controlling the biogeochemical cycles of nutrients (including carbon, nitrogen and phosphorus), heavy metals and aluminium in the environment. In many parts of the world, the effect of changing patterns in temperature, precipitation and acid deposition on the dynamics of organic carbon in soils and streams has received much attention. There is an increasing awareness of the importance of organic nitrogen both as a direct nutrient source and for its role in nutrient transport from the terrestrial to marine environment. The transport of mercury and other heavy metals is closely coupled to that of organic matter and the relationship between DOM and aluminium is still the subject of much research. Changes in organic matter quantity and quality will affect soil:solution partitioning, metal transport and nutrient status in surface waters. The observed temporal and spatial variation of the export of DOM, metals and nutrients in many lower order streams is controlled by both hydrology and biogeochemistry, both of which will potentially be affected by future changes in temperature, rainfall and deposition patterns. In this session we would like to invite experimenters, modellers and those analyzing long-term data in catchments and/or soils in different climate zones to present new approaches to a better understanding of how organic matter is exported from the soils to the stream and how this controls nutrient and metal dynamics at the catchment scale.