Predicting Reactive Intermediate Quantum Yields from Dissolved Organic Matter Photolysis Using Optical Properties and Antioxidant Capacity

2017 ◽  
Vol 51 (10) ◽  
pp. 5404-5413 ◽  
Author(s):  
Garrett Mckay ◽  
Wenxi Huang ◽  
Cristina Romera-Castillo ◽  
Jenna E. Crouch ◽  
Fernando L. Rosario-Ortiz ◽  
...  
Keyword(s):  
Organic Matter ◽  
Optical Properties ◽  
Dissolved Organic Matter ◽  
Antioxidant Capacity ◽  
Quantum Yields ◽  
Reactive Intermediate

scholarly journals Optical Properties of Dissolved Organic Matter in Urban Fountains

2019 ◽  
Vol 221 ◽  
pp. 012112
Author(s):  
Katarzyna Parszuto ◽  
Renata Tandyrak ◽  
Renata Augustyniak ◽  
Jolanta Grochowska ◽  
Michal Lopata ◽  
...  
Keyword(s):  
Organic Matter ◽  
Optical Properties ◽  
Dissolved Organic Matter

scholarly journals Optical Properties and Photochemical Transformation of the Dissolved Organic Matter Released by Sargassum

2020 ◽  
Vol 7 ◽  
Author(s):  
Leanne C. Powers ◽  
Rossana Del Vecchio ◽  
Neil V. Blough ◽  
Natasha McDonald ◽  
Philippe Schmitt-Kopplin ◽  
...  
Keyword(s):  
Organic Matter ◽  
Optical Properties ◽  
Dissolved Organic Matter ◽  
Photochemical Transformation

scholarly journals Spatio-seasonal variability of chromophoric dissolved organic matter absorption and responses to photobleaching in a large shallow temperate lake

2017 ◽  
Vol 14 (5) ◽  
pp. 1215-1233 ◽  
Author(s):  
María Encina Aulló-Maestro ◽  
Peter Hunter ◽  
Evangelos Spyrakos ◽  
Pierre Mercatoris ◽  
Attila Kovács ◽  
...  
Keyword(s):  
Organic Matter ◽  
Optical Properties ◽  
Dissolved Organic Matter ◽  
Seasonal Variability ◽  
Chromophoric Dissolved Organic Matter ◽  
Lake Balaton ◽  
Spectral Slope ◽  
Marked Variability ◽  
Rich Material ◽  
Development And Validation

Abstract. The development and validation of remote-sensing-based approaches for the retrieval of chromophoric dissolved organic matter (CDOM) concentrations requires a comprehensive understanding of the sources and magnitude of variability in the optical properties of dissolved material within lakes. In this study, spatial and seasonal variability in concentration and composition of CDOM and the origin of its variation was studied in Lake Balaton (Hungary), a large temperate shallow lake in central Europe. In addition, we investigated the effect of photobleaching on the optical properties of CDOM through in-lake incubation experiments. There was marked variability throughout the year in CDOM absorption in Lake Balaton (aCDOM(440) = 0. 06–9.01 m−1). The highest values were consistently observed at the mouth of the main inflow (Zala River), which drains humic-rich material from the adjoining Kis-Balaton wetland, but CDOM absorption decreased rapidly towards the east where it was consistently lower and less variable than in the westernmost lake basins. The spectral slope parameter for the interval of 350–500 nm (SCDOM(350–500)) was more variable with increasing distance from the inflow (observed range 0.0161–0.0181 nm−1 for the mouth of the main inflow and 0.0158–0.0300 nm−1 for waters closer to the outflow). However, spatial variation in SCDOM was more constant exhibiting a negative correlation with aCDOM(440). Dissolved organic carbon (DOC) was strongly positively correlated with aCDOM(440) and followed a similar seasonal trend but it demonstrated more variability than either aCDOM or SCDOM with distance through the system. Photobleaching resulting from a 7-day exposure to natural solar UV radiation resulted in a marked decrease in allochthonous CDOM absorption (7.04 to 3.36 m−1, 42 % decrease). Photodegradation also resulted in an increase in the spectral slope coefficient of dissolved material.

scholarly journals Photomineralization and photomethanification of dissolved organic matter in Saguenay River surface water

2015 ◽  
Vol 12 (22) ◽  
pp. 6823-6836 ◽  
Author(s):  
Y. Zhang ◽  
H. Xie
Keyword(s):  
Organic Matter ◽  
Surface Water ◽  
Dissolved Organic Matter ◽  
Dimethyl Sulfide ◽  
Ultraviolet B ◽  
Global Ocean ◽  
Quantum Yields ◽  
Methyl Radical ◽  
Ch4 Production ◽  
Saguenay River

Abstract. Rates and apparent quantum yields of photomineralization (AQYDOC) and photomethanification (AQYCH4) of chromophoric dissolved organic matter (CDOM) in Saguenay River surface water were determined at three widely differing dissolved oxygen concentrations ([O2]) (suboxic, air saturation, and oxygenated) using simulated-solar radiation. Photomineralization increased linearly with CDOM absorbance photobleaching for all three O2 treatments. Whereas the rate of photochemical dissolved organic carbon (DOC) loss increased with increasing [O2], the ratio of fractional DOC loss to fractional absorbance loss showed an inverse trend. CDOM photodegradation led to a higher degree of mineralization under suboxic conditions than under oxic conditions. AQYDOC determined under oxygenated, suboxic, and air-saturated conditions increased, decreased, and remained largely constant with photobleaching, respectively; AQYDOC obtained under air saturation with short-term irradiations could thus be applied to longer exposures. AQYDOC decreased successively from ultraviolet B (UVB) to ultraviolet A (UVA) to visible (VIS), which, alongside the solar irradiance spectrum, points to VIS and UVA being the primary drivers for photomineralization in the water column. The photomineralization rate in the Saguenay River was estimated to be 2.31 × 108 mol C yr−1, accounting for only 1 % of the annual DOC input into this system. Photoproduction of CH4 occurred under both suboxic and oxic conditions and increased with decreasing [O2], with the rate under suboxic conditions ~ 7–8 times that under oxic conditions. Photoproduction of CH4 under oxic conditions increased linearly with photomineralization and photobleaching. Under air saturation, 0.00057 % of the photochemical DOC loss was diverted to CH4, giving a photochemical CH4 production rate of 4.36 × 10−6 mol m−2 yr−1 in the Saguenay River and, by extrapolation, of (1.9–8.1) × 108 mol yr−1 in the global ocean. AQYCH4 changed little with photobleaching under air saturation but increased exponentially under suboxic conditions. Spectrally, AQYCH4 decreased sequentially from UVB to UVA to VIS, with UVB being more efficient under suboxic conditions than under oxic conditions. On a depth-integrated basis, VIS prevailed over UVB in controlling CH4 photoproduction under air saturation while the opposite held true under O2-deficiency. An addition of micromolar levels of dissolved dimethyl sulfide (DMS) substantially increased CH4 photoproduction, particularly under O2-deficiency; DMS at nanomolar ambient concentrations in surface oceans is, however, unlikely a significant CH4 precursor. Results from this study suggest that CDOM-based CH4 photoproduction only marginally contributes to the CH4 supersaturation in modern surface oceans and to both the modern and Archean atmospheric CH4 budgets, but that the photochemical term can be comparable to microbial CH4 oxidation in modern oxic oceans. Our results also suggest that anoxic microniches in particulate organic matter and phytoplankton cells containing elevated concentrations of precursors of the methyl radical such as DMS may provide potential hotspots for CH4 photoproduction.

Optical properties and molecular diversity of dissolved organic matter in the Bering Strait and Chukchi Sea

2017 ◽  
Vol 144 ◽  
pp. 104-111 ◽  
Author(s):  
Michael Gonsior ◽  
Jenna Luek ◽  
Philippe Schmitt-Kopplin ◽  
Jacqueline M. Grebmeier ◽  
Lee W. Cooper
Keyword(s):  
Organic Matter ◽  
Optical Properties ◽  
Dissolved Organic Matter ◽  
Molecular Diversity ◽  
Chukchi Sea ◽  
Bering Strait

Size fractionation and optical properties of dissolved organic matter in the continuum soil solution-bog-river and terminal lake of a boreal watershed

2014 ◽  
Vol 66 ◽  
pp. 14-24 ◽  
Author(s):  
Svetlana M. Ilina ◽  
Olga Yu. Drozdova ◽  
Sergey A. Lapitskiy ◽  
Yuriy V. Alekhin ◽  
Vladimir V. Demin ◽  
...  
Keyword(s):  
Organic Matter ◽  
Optical Properties ◽  
Dissolved Organic Matter ◽  
Soil Solution ◽  
Size Fractionation ◽  
The Continuum
Sign in / Sign up

Export Citation Format

Share Document