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A new approach for parameterizing dissolved organic matter (DOM) ultraviolet-visible absorption spectra is presented. Two distinct spectral slope regions (275–295 nm and 350–400 nm) within log-transformed absorption spectra were used to compare DOM from contrasting water types, ranging from wetlands (Great Dismal Swamp and Suwannee River) to photobleached(More)
Photochemical production rates and steady-state concentrations of hydroxyl radicals (.OH) were measured in sunlight-irradiated seawater. Values ranged from 110 nanomolar per hour and 12 x 10(-18) molar in coastal surface water to 10 nanomolar per hour and 1.1 x 10(-18) molar in open ocean surface water. The wavelengths responsible for this production are in(More)
Diel and depth variations in dissolved free amino acids and ammonium in the Baltic Sea determined by shipboard HPLC analysis' Abstract A precolumn fluorimetric labeling method was tested for shipboard HPLC analysis of dissolved fret amino acids (DFAA) in natural waters. No sample preparation is required and all naturally occurring amino acids plus ammonium(More)
We performed laboratory studies to determine the effects of salinity on the photodegradation of dissolved organic matter (DOM) from the Great Dismal Swamp, Virginia, an important source of terrestrial DOM to the lower Chesapeake Bay. Samples were created by mixing Great Dismal Swamp water (ionic strength < 0 mol L 21) with modified artificial seawater(More)
Two water samples from the Great Dismal Swamp National Wildlife Refuge with high dissolved organic matter (DOM) concentrations (51 and 121 mg C L−1) were subjected to ultraviolet (UV) light for up to 110 days. During the course of the irradiations, 74–88 % of the original dissolved organic carbon was lost along with 95–99 % of the absorption at 300 nm.(More)
The interaction of the vertically variable UV-visible radiation field and mixing in the surface waters of aquatic systems has long been appreciated as a fundamental factor affecting photosynthesis (e.g., Falkowski 1983; Lewis et al. 1984a, 1984b; Falkowski and Wirick 1981) and nonbiological pho-toreactions such as photodegradation of natural and(More)
In this study, we examined hydroxyl radical (OH) formation with respect to photoreactivity of colored dissolved organic matter (CDOM), the Fenton reaction, and photoflocculation using leachate from decaying wood. The relationship between OH photoproduction rate and leachate optical properties (UV-visible absorption and fluorescence excitation-emission(More)
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