Characterization and comparison of dissolved organic matter composition of aquatic systems from São Paulo State by high resolution wings and accurate mass spectrometry

Author(s)

José Javier Melendez Pérez

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Química
• Defense date: 2017-01-16

Examining board members

Marcos Nogueira Eberlin; Pedro Sérgio Fadini; Wanderson Romão; Carla Beatriz Grespan Bottoli; Anne Hélène Fostier

• Advisor: Marcos Nogueira Eberlin

Abstract

Dissolved organic matter (DOM) is defined as the organic components in water that pass through a 0.7 ?m filter. DOM is an important component of the global carbon cycle and small changes in its size and dynamics can potentially impact many of Earth's biogeochemical systems with consequences on global warming and aquatic life (Hedges et al., 1997). Fourier transform high-resolution ion cyclotron resonance mass spectrometry (FT-ICR MS) was used for characterization of DOM from water systems of São Paulo state such as the Cananéia estuary, continental shelf near Ubatuba, the Monjolinho River and the Hermógenes Leitão Filho lagoon (HLPF lagoon) with the aim to understanding the composition and origin of the soluble organic compounds present in these environments. The characterization of DOM allowed the identification of homologous séries of compounds and useful markers to better understand the geochemical processes related with the origin of DOM and their influence on the carbon and sulfur cycle. Visualization tools such as van Kreveler diagrams and bar charts of compound classes were used to facilitate the interpretation and grouping of the enormous number of data generated in DOM mass spectra and results from each sample and system were compared. The study and interpretation of graphs and homologous séries allowed to identify several types of ionizable compounds that are present in the DOM such as lignin derivatives, surfactants from human activities, polyoxygenated compounds (CHOS) and lipids. The geochemical process responsible for the formation of the CHOS compounds in the DOM was also demonstrated, a reaction mechanism was proposed for the formation of these compounds and a correction was proposed for the calculation of the aromaticity index which can be used in the characterization by high resolution mass spectrometry of complex natural mixtures containing condensed aromatic compounds. The present doctoral thesis was presented in the alternative format according to INFORMATION CCPG / 001/2015 of the State University of Campinas (AU)

• FAPESP's process: 13/15644-0 - Use of ultrahigh resolution and accurate mass spectrometry techniques in marine organic: characterization of dissolved organic matter in the estuary-lagoon system of Cananéia-Iguape and comparison with other environments in São Paulo state.
• Grantee: Jose Javier Melendez Perez
• Support Opportunities: Scholarships in Brazil - Doctorate