title: Photo-dissolution of flocculent, detrital material in aquatic environments: contributions to the dissolved organic matter pool.
abstract: This study shows that light exposure of flocculent material (floc) from the Florida Coastal Everglades (FCE) results in significant dissolved organic matter (DOM) generation through photo-dissolution processes. Floc was collected at two sites along the Shark River Slough (SRS) and irradiated with artificial sunlight. The DOM generated was characterized using elemental analysis and excitation emission matrix fluorescence coupled with parallel factor analysis. To investigate the seasonal variations of DOM photo-generation from floc, this experiment was performed in typical dry (April) and wet (October) seasons for the FCE. Our results show that the dissolved organic carbon (DOC) for samples incubated under dark conditions displayed a relatively small increase, suggesting that microbial processes and/or leaching might be minor processes in comparison to photo-dissolution for the generation of DOM from floc. On the other hand, DOC increased substantially (as much as 259 mgC gC(-1)) for samples exposed to artificial sunlight, indicating the release of DOM through photo-induced alterations of floc. The fluorescence intensity of both humic-like and protein-like components also increased with light exposure. Terrestrial humic-like components were found to be the main contributors (up to 70%) to the chromophoric DOM (CDOM) pool, while protein-like components comprised a relatively small percentage (up to 16%) of the total CDOM. Simultaneously to the generation of DOC, both total dissolved nitrogen and soluble reactive phosphorus also increased substantially during the photo-incubation period. Thus, the photo-dissolution of floc can be an important source of DOM to the FCE environment, with the potential to influence nutrient dynamics in this system.
authors.affiliation: Southeast Environmental Research Center, and Department of Chemistry & Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, USA.
authors.forename: Oliva
authors.initials: O
authors.lastname: Pisani
authors.forename: Youhei
authors.initials: Y
authors.lastname: Yamashita
authors.forename: Rudolf
authors.initials: R
authors.lastname: Jaffé
mesh_terms: D002244:Carbon / Q000737:chemistry; D004784:Environmental Monitoring; D005427:Flocculation; D009584:Nitrogen / Q000737:chemistry; D009930:Organic Chemicals / Q000737:chemistry*; D010758:Phosphorus / Q000737:chemistry; D010777:Photochemistry / Q000379:methods*; D013050:Spectrometry, Fluorescence; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D009930:Organic Chemicals; D014874:Water Pollutants, Chemical; D010758:Phosphorus; D002244:Carbon; D009584:Nitrogen