Biogeochemical cycle of carbon in rivers: an integrative approach through analysis without multiscales using multiple tracers

• Grant number: 00/07006-4
• Support Opportunities: Research Grants - Young Investigators Grants
• Start date: October 01, 2000
• End date: September 30, 2004
• Field of knowledge: Biological Sciences - Ecology - Ecosystems Ecology
• Principal Investigator: Alex Vladimir Krusche
• Grantee: Alex Vladimir Krusche
• Host Institution: Centro de Energia Nuclear na Agricultura (CENA). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

To understand the biogeochemical cycle of carbono in river systems in such a way as to describe it by means of a comprehensive functional model is one of the most important objectives of the studies undertaken in these systems. Research carried out in the Amazon river over the last 20 years led to the formulation of one of these models, known as River Basin Organic Matter and Biogeochemistry Synthesis (Rombus). However, this model is based merely on results obtained in this river on a continental scale, and its validity for systems of micro and mesoscale is still an unknown quantity, which the project intends to ascertain. To this end, we will expand the experiments previously carried out on that scale for small igarapés (narrow riverbanks) on the Nova Vida Farm and for the river Ji-Paraná, all located in the basin of the river Madeira, in the state of Rondônia. In this way, the validity of the model will be tested also for micro and mesoscales. Such experiments, their results and the formulation of the model presuppose the fractioning of organic matter in physically quantifiable units and its elemental, isotopic and molecular speciation.While the first two (elemental and isotopic) provide important information on the sources of carbon in transport in the river systems, based on the latter unit (molecular) it is also possible to infer the degree of diagenetic alteration of the organic matter. Associated with direct measurements of the metabolic rates and of possible substrates of the same, as organic compounds of low molecular weight, this study expands and consolidates organic geochemistry as a line of research in the CENA Isotopic Ecology Laboratory in (USP), implementing analytical techniques still far from common in this area of knowledge in Brazil. (AU)