ABSTRACT
River networks represent the largest biogeochemical nexus between the continents, ocean and atmosphere. Our current understanding of the role of rivers in the global carbon cycle remains limited, which makes it difficult to predict how global change may alter the timing and spatial distribution of riverine carbon sequestration and greenhouse gas emissions, and the metabolic regime of stream ecosystems.
The key components of stream ecosystem metabolism are gross primary production, which is the carbon fixed through photosynthesis by primary producers (autotrophs) and ecosystem respiration (ER), which is the sum of the carbon respired by both heterotrophs and autotrophs. In addition to instream primary production, fluvial networks collect significant amount of organic carbon from the adjacent terrestrial ecosystems. Such carbon can be respired by microbial heterotrophs to carbon dioxide (CO2) ultimately evading to the atmosphere, or transiently buried in the sediments of fringing floodplains or impoundments, or simply exported to the oceans. The balance among these fluxes determines the metabolic regimes of river networks.
The seminar will illustrate recent advances in this context with particular reference to: i) the hydrologic controls on stream carbon cycling and ii) the use of modelling and network scaling theory to transfer knowledge from the reach scale, where most of experiments and observations are carried out, to the catchment, regional and global scales.
SHORT BIO
Enrico Bertuzzo is full professor of hydrology at the Department of Environmental Science, Informatics and Statistics at the University of Venice Ca’ Foscari. He focuses on ecohydrology studying the hydrologic controls on stream and river ecosystems.