Photodegradation of DOC in a shallow prairie wetland: evidence from seasonal changes in DOC optical properties and chemical characteristics

摘要: Wetlands across the Canadian prairies are typically shallow ( 10 mg l−1). Studies have shown that DOC in such wetlands is not as reliable an indicator of ultraviolet radiation (UVR) attenuation it clearwater. Changes character and composition a result sunlight exposure might provide reasonable explanation for this observation. To test this, we investigated seasonal changes optical chemical properties prairie wetland over 2-year period. Although concentration increased at least two-fold from spring until fall, specific absorption (at 350 nm) fluorescence decreased by 30 32%, respectively, same In both years, decreases molecular weight size (from measurements tangential filtration mass electrospray spectrometry) were reflected concomitant increases spectral slope. 13C NMR analysis isolated on XAD-8 resins revealed 49% decrease aromatic moieties when values compared to those fall. As well, δ13C signatures became heavier seasonally. short term photodegradation experiment (6 days) noted 47% decline coefficients nm 15% increase slope water exposed total light spectrum was dark control. Taken together, all these observations consistent with occurrence underlined importance process shaping hydrologically dynamic systems. Our data also indicates constant mixing depths factors which enhanced photodegradation. high concentrations should theoretically offer protection their biota, means systems may be protected suggest.