scholarly journals Methylmercury Photodegradation in Surface Water of the Florida Everglades: Importance of Dissolved Organic Matter-Methylmercury Complexation

2014 ◽  
Vol 48 (13) ◽  
pp. 7333-7340 ◽  
Author(s):  
Chao Tai ◽  
Yanbin Li ◽  
Yongguang Yin ◽  
Leonard J. Scinto ◽  
Guibin Jiang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Surface Water ◽  
Dissolved Organic Matter ◽  
Florida Everglades

Removal of the Neutral Dissolved Organic Matter (NDOM) from Surface Water by Coagulation/Flocculation and Nanofiltration

2021 ◽  
pp. 1-14
Author(s):  
Sami Khettaf ◽  
Roumaissa Boumaraf ◽  
Fatiha Benmahdi ◽  
Kamel-Eddine Bouhidel ◽  
Mohammed Bouhelassa
Keyword(s):  
Organic Matter ◽  
Surface Water ◽  
Dissolved Organic Matter

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.

Molecular characterization of dissolved organic matter in freshwater wetlands of the Florida Everglades

2003 ◽  
Vol 37 (11) ◽  
pp. 2599-2606 ◽  
Author(s):  
X.Q. Lu ◽  
N. Maie ◽  
J.V. Hanna ◽  
D.L. Childers ◽  
R. Jaffé
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Molecular Characterization ◽  
Freshwater Wetlands ◽  
Florida Everglades

scholarly journals Surface water treatment by UV/H2O2 with subsequent soil aquifer treatment: impact on micropollutants, dissolved organic matter and biological activity

2019 ◽  
Vol 5 (10) ◽  
pp. 1709-1722 ◽  
Author(s):  
Robin Wünsch ◽  
Julia Plattner ◽  
David Cayon ◽  
Fabienne Eugster ◽  
Jens Gebhardt ◽  
...  
Keyword(s):  
Organic Matter ◽  
Biological Activity ◽  
Water Treatment ◽  
Surface Water ◽  
Dissolved Organic Matter ◽  
Microbial Activity ◽  
Soil Aquifer Treatment ◽  
Organic Micropollutants ◽  
Total Removal ◽  
Surface Water Treatment

UV/H2O2 treatment of sand-filtered surface water before soil aquifer treatment increases the total removal of organic micropollutants and has an impact on microbial activity without pronounced effects on dissolved organic matter removal.

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