Polar organic compounds in pore waters of the Chesapeake Bay impact structure, Eyreville core hole: Character of the dissolved organic carbon and comparison with drilling fluids

2009 ◽  
Author(s):  
Colleen E. Rostad ◽  
Ward E. Sanford
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Chesapeake Bay ◽  
Organic Compounds ◽  
Drilling Fluids ◽  
Impact Structure ◽  
Pore Waters ◽  
Core Hole ◽  
Polar Organic Compounds

scholarly journals Photooxidants from Brown Carbon and Other Chromophores in Illuminated Particle Extracts

2018 ◽  
Author(s):  
Richie Kaur ◽  
Jacqueline R. Labins ◽  
Scarlett S. Helbock ◽  
Wenqing Jiang ◽  
Keith Bein ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Organic Compounds ◽  
Excited States ◽  
Liquid Water ◽  
Light Absorption ◽  
Singlet Molecular Oxygen ◽  
Brown Carbon ◽  
Aggregate Rate ◽  
Triplet Excited States

Abstract. While photooxidants are important in atmospheric condensed phases, there are very few measurements in particulate matter (PM). Here we measure light absorption and the concentrations of three photooxidants – hydroxyl radical (•OH), singlet molecular oxygen (1O2*) and oxidizing triplet excited states of organic matter (3C*) – in illuminated aqueous extracts of wintertime particles from Davis, California. 1O2* and 3C*, which are formed from photoexcitation of brown carbon (BrC), have not been previously measured in PM. In the extracts, mass absorption coefficients for dissolved organic compounds (MACDOC) at 300 nm range between 13,000–30,000 cm2 g–C–1 and are approximately twice as high as previous values in Davis fogs. The average (± 1σ) •OH steady-state concentration in particle extracts is 4.7 (± 1.9) × 10−16 M, which is very similar to previous values in fog, cloud and rain: although our particle extracts are more concentrated, the resulting enhancement in the rate of •OH photoproduction is essentially cancelled out by a corresponding enhancement in concentrations of natural sinks for •OH. In contrast, concentrations of the two oxidants formed primarily from brown carbon (i.e., 1O2* and 3C*) are both enhanced in the particle extracts compared to Davis fogs, a result of higher concentrations of dissolved organic carbon and faster rates of light absorption in the extracts. The average 1O2* concentration in the PM extracts is 1.6 (± 0.5) × 10−12 M, seven times higher than past fog measurements, while the average concentration of oxidizing triplets is 1.0 (± 0.4) × 10−13 M, nearly double the average Davis fog value. Additionally, the rates of 1O2* and 3C* photoproduction are both well correlated with the rate of sunlight absorption. While concentrations of 1O2* and 3C* are higher in our PM extracts compared to fog, the extracts are approximately 1000 times more dilute than water-containing ambient PM. Since we cannot experimentally measure photooxidants under these ambient conditions, we measured the effect of PM dilution on oxidant concentrations and then extrapolated to ambient particle conditions. As the particle mass concentration in the extracts increases, measured concentrations of •OH remain relatively unchanged, 1O2* increases linearly, and 3C* concentrations increase less than linearly, likely due to quenching by dissolved organics. Based on our measurements, and accounting for additional sources and sinks that should be important under PM conditions, we estimate that [•OH] in particles is essentially the same as in fog waters, [3C*] is higher in PM by nearly a factor of 3, and [1O2*] is enhanced by a factor of roughly 600. Because of these enhancements in 1O2* and 3C* concentrations, the lifetimes of some highly soluble organics appear to be much shorter in particle liquid water than under foggy/cloudy conditions. Based on our extrapolated rates of formation, BrC-derived singlet molecular oxygen and triplet excited states are the dominant sinks for organic compounds in particle liquid water, with an aggregate rate of reaction for each oxidant that is approximately 200–300 times higher than the aggregate rate of reactions for organics with •OH. For individual, highly soluble reactive organic compounds it appears that 1O2* is the major sink in particle water. Triplet excited states are likely also important in the fate of individual particulate organics, but assessing this requires additional measurements of triplet interactions with dissolved organic carbon in natural samples.

Fluxes of dissolved organic carbon from Chesapeake Bay sediments

1994 ◽  
Vol 58 (16) ◽  
pp. 3407-3424 ◽  
Author(s):  
David J. Burdige ◽  
Juliana Homstead
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Chesapeake Bay

Effect of landuse on the composition of throughflow water immediately above clayey B horizons in the Warren Catchment, South Australia

1993 ◽  
Vol 33 (2) ◽  
pp. 239 ◽  
Author(s):  
R Naidu ◽  
DR Williamson ◽  
RW Fitzpatrick ◽  
IO Hollingsworth
Keyword(s):  
Electrical Conductivity ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Organic Compounds ◽  
South Australia ◽  
Total Dissolved Solids ◽  
Rate Of Change ◽  
Native Woodland ◽  
Colloidal Matter ◽  
Dissolved Organic Compounds

The effect of landuse on composition of throughflow water immediately above the clayey B horizons in duplex soils (mostly natric and/or sodic) in the Mount Lofty Ranges, South Australia, was investigated using simple lysimeters. During July-November 1991, the pH of the first flow immediately after rainstorm under pines, native woodland, and pasture, respectively, was 5.7, 6.0, and 6.4. At each of the sites, average pH over 4 months during July-November was 5.8-5.9. Both the electrical conductivity (EC) and the amounts of total dissolved solids (TDS) were 2-3 times higher under pine than at other sites. The rate of change in EC with respect to TDS varied considerably among the sites, possibly due to the large differences in the concentration of dissolved organic compounds. Although the pH of water was >5.5, both aluminium and iron were recorded, especially under pine, where there were also high levels of dissolved organic compounds. High levels of suspended colloidal matter were recorded in the water flowing under pine, and these levels were related to dissolved organic carbon.

Spatial and seasonal variations of sulphate, dissolved organic carbon, and nutrients in deep pore waters of intertidal flat sediments

2008 ◽  
Vol 79 (2) ◽  
pp. 307-316 ◽  
Author(s):  
Melanie Beck ◽  
Olaf Dellwig ◽  
Gerd Liebezeit ◽  
Bernhard Schnetger ◽  
Hans-Jürgen Brumsack
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Seasonal Variations ◽  
Intertidal Flat ◽  
Pore Waters
Sign in / Sign up

Export Citation Format

Share Document