Evidence for dissolved organic matter as the primary source and sink of photochemically produced hydroxyl radical in arctic surface waters

2014 ◽  
Vol 16 (4) ◽  
pp. 807-822 ◽  
Author(s):  
Sarah E. Page ◽  
J. Robert Logan ◽  
Rose M. Cory ◽  
Kristopher McNeill
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Hydroxyl Radical ◽  
Residence Time ◽  
Surface Waters ◽  
Primary Source ◽  
The Arctic ◽  
Water Residence Time ◽  
Arctic Surface ◽  
Source And Sink

Photochemical hydroxyl radical formation decreases with increasing water residence time in a system of lakes connected by streams in the Arctic.

scholarly journals Assessing the prevalence, products, and pathways of dissolved organic matter partial photo-oxidation in arctic surface waters

2020 ◽  
Vol 22 (5) ◽  
pp. 1214-1223 ◽  
Author(s):  
Collin P. Ward ◽  
Rose M. Cory
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Surface Waters ◽  
Photochemical Oxidation ◽  
Photo Oxidation ◽  
Isotope Tracer ◽  
Arctic Surface ◽  
Tracer Experiments

Isotope tracer experiments reveal that rates of dissolved organic matter partial photochemical oxidation are considerably underestimated in arctic surface waters.

scholarly journals The composition and distribution of semi-labile dissolved organic matter across the southwest Pacific

2019 ◽  
Vol 16 (1) ◽  
pp. 105-116 ◽  
Author(s):  
Christos Panagiotopoulos ◽  
Mireille Pujo-Pay ◽  
Mar Benavides ◽  
France Van Wambeke ◽  
Richard Sempéré
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Residence Time ◽  
Surface Waters ◽  
Euphotic Zone ◽  
South Pacific ◽  
Bacterial Degradation ◽  
The South ◽  
Energy Limitation ◽  
South Pacific Gyre

Abstract. The distribution and dynamics of dissolved organic carbon (DOC) and dissolved combined neutral sugars (DCNS) were studied across an increasing oligotrophic gradient (18 to 22∘ S latitude) in the tropical South Pacific Ocean, spanning from the Melanesian Archipelago (MA) area to the western part of the South Pacific gyre (WGY), in austral summer as a part of the OUTPACE project. Our results show that DOC and DCNS concentrations exhibited no statistical differences between the MA and WGY areas (0–200 m: 47–81 µM C for DOC and 0.2-4.2 µM C for DCNS). However, due to a deepening of the euphotic zone, a deeper penetration of DOC was noticeable at 150 m of depth at the WGY area. Excess DOC (DOCEX) was determined as the difference between surface and deep-sea DOC values, and euphotic zone integrated stocks of both DOC and DOCEX were higher in the WGY than the MA area. Considering DOCEX as representative of semi-labile DOC (DOCSL), its residence time was calculated as the ratio of DOCSL to bacterial carbon demand (BCD). This residence time was 176±43 days (n=3) in the WGY area, about 3 times longer than in the MA area (Tr=51±13 days, n=8), suggesting an accumulation of semi-labile dissolved organic matter (DOM) in the surface waters of WGY. Average epipelagic (0–200 m) DCNS yields (DCNS × DOC−1) based on volumetric data were roughly similar in both areas, accounting for ∼2.8 % of DOC. DCNS exhibited a longer residence time in WGY (Tr=91±41 days, n=3) than in MA (Tr=31±10 days, n=8), further suggesting that this DCNS pool persists longer in the surface waters of the WGY. The accumulation of DOCEX in the surface waters of WGY is probably due to very slow bacterial degradation due to nutrient and/or energy limitation of heterotrophic prokaryotes, indicating that biologically produced DOC can be stored in the euphotic layer of the South Pacific gyre for a long period.

scholarly journals Using fluorescent dissolved organic matter to trace and distinguish the origin of Arctic surface waters

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Rafael Gonçalves-Araujo ◽  
Mats A. Granskog ◽  
Astrid Bracher ◽  
Kumiko Azetsu-Scott ◽  
Paul A. Dodd ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Surface Waters ◽  
Fluorescent Dissolved Organic Matter ◽  
Arctic Surface

The role of dissolved organic matter in arctic surface waters in the photolysis of hexachlorobenzene and lindane

2012 ◽  
Vol 117 (G1) ◽  
Author(s):  
Amanda M. Grannas ◽  
Rose M. Cory ◽  
Penney L. Miller ◽  
Yu-Ping Chin ◽  
Diane M. McKnight
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Surface Waters ◽  
Arctic Surface

scholarly journals Optical properties and bioavailability of dissolved organic matter along a flow-path continuum from soil pore waters to the Kolyma River mainstem, East Siberia

2016 ◽  
Vol 13 (8) ◽  
pp. 2279-2290 ◽  
Author(s):  
Karen E. Frey ◽  
William V. Sobczak ◽  
Paul J. Mann ◽  
Robert M. Holmes
Keyword(s):  
Organic Matter ◽  
Optical Properties ◽  
Dissolved Organic Matter ◽  
Residence Time ◽  
Flow Path ◽  
The Arctic ◽  
Pore Waters ◽  
Water Types ◽  
Kolyma River ◽  
Dom Composition

Abstract. The Kolyma River in northeast Siberia is among the six largest Arctic rivers and drains a region underlain by vast deposits of Holocene-aged peat and Pleistocene-aged loess known as yedoma, most of which is currently stored in ice-rich permafrost throughout the region. These peat and yedoma deposits are important sources of dissolved organic matter (DOM) to inland waters that in turn play a significant role in the transport and ultimate remineralization of organic carbon to CO2 and CH4 along the terrestrial flow-path continuum. The turnover and fate of terrigenous DOM during offshore transport largely depends upon the composition and amount of carbon released to inland and coastal waters. Here, we measured the ultraviolet-visible optical properties of chromophoric DOM (CDOM) from a geographically extensive collection of waters spanning soil pore waters, streams, rivers, and the Kolyma River mainstem throughout a  ∼  250 km transect of the northern Kolyma River basin. During the period of study, CDOM absorption coefficients were found to be robust proxies for the concentration of DOM, whereas additional CDOM parameters such as spectral slopes (S) were found to be useful indicators of DOM quality along the flow path. In particular, the spectral slope ratio (SR) of CDOM demonstrated statistically significant differences between all four water types and tracked changes in the concentration of bioavailable DOC, suggesting that this parameter may be suitable for clearly discriminating shifts in organic matter characteristics among water types along the full flow-path continuum across this landscape. However, despite our observations of downstream shifts in DOM composition, we found a relatively constant proportion of DOC that was bioavailable ( ∼  3–6 % of total DOC) regardless of relative water residence time along the flow path. This may be a consequence of two potential scenarios allowing for continual processing of organic material within the system, namely (a) aquatic microorganisms are acclimating to a downstream shift in DOM composition and/or (b) photodegradation is continually generating labile DOM for continued microbial processing of DOM along the flow-path continuum. Without such processes, we would otherwise expect to see a declining fraction of bioavailable DOC downstream with increasing residence time of water in the system. With ongoing and future permafrost degradation, peat and yedoma deposits throughout the northeast Siberian region will become more hydrologically active, providing greater amounts of DOM to fluvial networks and ultimately to the Arctic Ocean. The ability to rapidly and comprehensively monitor shifts in the quantity and quality of DOM across the landscape is therefore critical for understanding potential future feedbacks within the Arctic carbon cycle.

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