Optical Spectroscopy to gain further insights on the chemical structure of humic substances (HS) and chromophoric dissolved organic matter (CDOM)

Academic Research Topics in Environmental Measurement and Monitoring
Oral Presentation

Prepared by R. Del Vecchio1, T. Schendorf2, N. Blough3
1 - ESSIC-University of Maryland, 5825 University Research Ct #4001, College Park, Maryland, 20740, United States
2 - Dept of Chemistry and Biochemistry, , College Park, MD, 20742, United States
3 - Department of Chemistry and Biochemistry, , College Park, MD, 20742, United States


Contact Information: rossdv@umd.edu; 240-502-5381


ABSTRACT

HS have been studied extensively over the last decades yet the structural basis giving rise to their optical properties is still highly debated. Aromatic ketones, aldehydes and quinones along with carboxylic groups and phenolic moieties are significant constituents of HS yet their contribution to the optical properties is only recently being investigated. Chemical manipulation of selected functional groups is an extremely promising approach to highlight the contribution of such groups to the HS (and CDOM) optical properties. Thus, chemical reduction (and re-oxidation) along with pH titrations are employed herein to assess the relative contribution of aromatic ketones/aldehydes/quinones and carboxylic groups/phenolic moieties to the optical properties of HS (and CDOM). Results will be presented in context with our proposed charge-transfer model. This approach can be applied to other optically active environmental constituents or contaminants difficult to monitor or measure.