title: Analysis of extinction in ultraviolet and visible spectra of water bodies of the Paraguay and Brazil wetlands.
abstract: The extinction spectra in ultraviolet and visible radiation were analyzed using filtered and unfiltered water samples obtained in 11 open water bodies in the Neembucù (Paraguay) and Pantanal (Brazil) wetlands. The role of dissolved and suspended matter in the total extinction was analyzed between 260 nm and 700 nm. The chromophoric dissolved organic matter (CDOM) was the major component in extinction of considered ultraviolet radiation (260-400 nm). The differences in CDOM concentrations explained the main pattern of extinction of the ultraviolet radiation in the samples. Nevertheless, differences between the studied water bodies were found also to depend on the rate of photodegradation and photobleaching. The methodology developed in the present study was to distinguish "humic optic waters" according to quantity and quality of dissolved and suspended matter present. In the "humic optic water", the penetration of 10% of incident UV radiation and the photoactive layer are estimated. The influence of particulate matter increases in the total extinction of the wavelengths higher than 400 nm. The integral of the extinction curve of suspended matter in the visible wavelengths (400-700 nm) was found to relate with the total suspended solids and chlorophyll concentrations.
authors.affiliation: Dipartimento di Scienze e Tecnologie Chimiche e dei Biosistemi, Università di Siena, Via Aldo Moro 1, 53100 Siena, Italy. bracchini@unisi.it
authors.forename: Luca
authors.initials: L
authors.lastname: Bracchini
authors.forename: Andrés
authors.initials: A
authors.lastname: Cózar
authors.forename: Arduino M
authors.initials: AM
authors.lastname: Dattilo
authors.forename: Margherita
authors.initials: M
authors.lastname: Falcucci
authors.forename: Rafael
authors.initials: R
authors.lastname: Gonzales
authors.forename: Steven
authors.initials: S
authors.lastname: Loiselle
authors.forename: Vincent
authors.initials: V
authors.lastname: Hull
mesh_terms: D001938:Brazil; D002734:Chlorophyll / Q000032:analysis; D000077194:Chlorophyll A; D005618:Fresh Water / Q000032:analysis*; D008027:Light; D009930:Organic Chemicals / Q000737:chemistry*; D010239:Paraguay; D010777:Photochemistry; D012044:Regression Analysis; D013053:Spectrophotometry; D014466:Ultraviolet Rays
chemical_list: D009930:Organic Chemicals; D002734:Chlorophyll; D000077194:Chlorophyll A