Dissolved organic matter photolysis in Canadian arctic thaw ponds

Laurion, Isabelle; Mladenov, Natalie

doi:10.1088/1748-9326/8/3/035026

Cited by 74 publications

(77 citation statements)

References 57 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The net CH 4 production rates from the ponds in our study area were of a similar magnitude to observed summertime CH 4 emission rates (excluding ebullition) from ice-wedge ponds on Bylot Island. In addition, the results of this study provide further evidence that the marked differences in net CH 4 production rates between the different pond types are likely to be due to fundamental differences in biogeochemical processes resulting from active thermal erosion which increases the availability of organic material (Laurion et al, 2010;Laurion and Mladenov, 2013).…”

Section: Ch 4 Concentrations and Net Production Ratesmentioning

confidence: 61%

Frozen ponds: production and storage of methane during the Arctic winter in a lowland tundra landscape in northern Siberia, Lena River delta

et al. 2015

View full text Add to dashboard Cite

Abstract. Lakes and ponds play a key role in the carbon cycle of permafrost ecosystems, where they are considered to be hotspots of carbon dioxide CO 2 and methane CH 4 emission. The strength of these emissions is, however, controlled by a variety of physical and biogeochemical processes whose responses to a warming climate are complex and only poorly understood. Small waterbodies have been attracting an increasing amount of attention since recent studies demonstrated that ponds can make a significant contribution to the CO 2 and CH 4 emissions of tundra ecosystems. Waterbodies also have a marked effect on the thermal state of the surrounding permafrost; during the freezing period they prolong the period of time during which thawed soil material is available for microbial decomposition.This study presents net CH 4 production rates during the freezing period from ponds within a typical lowland tundra landscape in northern Siberia. Rate estimations were based on CH 4 concentrations measured in surface lake ice from a variety of waterbody types. Vertical profiles along ice blocks showed an exponential increase in CH 4 concentration with depth. These CH 4 profiles were reproduced by a 1-D mass balance model and the net CH 4 production rates were then inferred through inverse modeling.Results revealed marked differences in early winter net CH 4 production among various ponds. Ponds situated within intact polygonal ground structures yielded low net production rates, of the order of 10 −11 to 10 −10 mol m −2 s −1 (0.01 to 0.14 mg CH 4 m −2 day −1 ). In contrast, ponds exhibiting clear signs of erosion yielded net CH 4 production rates of the order of 10 −7 mol m −2 s −1 (140 mg CH 4 m −2 day −1 ). Our results therefore indicate that once a particular threshold in thermal erosion has been crossed, ponds can develop into major CH 4 sources. This implies that any future warming of the climate may result in nonlinear CH 4 emission behavior in tundra ecosystems.

show abstract

Section: Ch 4 Concentrations and Net Production Ratesmentioning

confidence: 61%

Frozen ponds: production and storage of methane during the Arctic winter in a lowland tundra landscape in northern Siberia, Lena River delta

et al. 2015

View full text Add to dashboard Cite

show abstract

“…4). C4, which has not been previously reported in the openfluor database, displayed an emission spectrum at longer wavelengths, indicating that this component likely contains highly aromatic molecules with very HMW compounds (Cory and McKnight 2005;Laurion and Mladenov 2013). In Cory and McKnight (2005), this component corresponds to semiquinones (SQ1).…”

Section: Fluorescence Characterization By Parafac Modelingmentioning

confidence: 69%

“…The absorption coefficient at 350 (E350) was calculated and represents a quantitative measure of the chromophoric fraction of DOM that is positively correlated with DOC and lignin phenol content (Spencer et al 2009;Laurion and Mladenov 2013;Mann et al 2016 ) (Weishaar et al 2003). SUVA 254 is positively correlated with bulk DOM aromaticity because aromatic compounds absorb more light in the UV-visible spectra.…”

Section: Dom Optical Indices and Parafac Modelingmentioning

confidence: 99%

“…Slope coefficients, which differ between DOM sources, have been reported to be indicators of molecular weight and aromaticity. Higher slope coefficients are associated with lower molecular weight and decreasing DOM aromaticity (i.e., more degraded and (or) microbial source) (Helms et al 2008;Mann et al 2012;Laurion and Mladenov 2013;Frey et al 2015).…”

Section: Dom Optical Indices and Parafac Modelingmentioning

confidence: 99%

See 1 more Smart Citation

Seasonal hydrology and permafrost disturbance impacts on dissolved organic matter composition in High Arctic headwater catchments

et al. 2017

View full text Add to dashboard Cite

Arctic landscapes are experiencing intense warming and modification of precipitation regimes with climate change. Permafrost disturbances and climate change impacts on hydrology of Arctic watersheds are likely to modify the quantity and composition of exported dissolved organic matter (DOM). In July 2007, intense rainfall and active layer thickening caused widespread active layer detachments at Cape Bounty, Melville Island (Canada). This study investigates the impacts of seasonal hydrology and permafrost disturbance on DOM composition exported from High Arctic headwater catchments. In 2012, streams were sampled from three disturbed catchments and one undisturbed catchment. The composition of DOM was characterized using absorbance and fluorescence spectroscopy. DOM was mostly exported during the spring freshet. Throughout this period, the undisturbed catchment exported humified DOM with high humic-like fluorescence that likely originated from runoff through shallow organic rich soil. In contrast, DOM exported from disturbed catchments was fresher, less humified with a high proportion of low molecular weight humic acid. We demonstrate that disturbed catchments delivered likely more labile DOM derived from either thawed permafrost or enhanced microbial activity. If this labile DOM comes from an ancient pool, as indicated by other studies at this site, disturbances may strengthen the permafrost carbon feedback on climate change.Key words: active layer detachments, dissolved organic matter, fluorescence, High Arctic, parallel factor analysis, PARAFAC.Résumé : Avec le changement climatique, les paysages arctiques connaissent un réchauffe-ment intense et une modification des régimes de précipitation. Les impacts des perturbations du pergélisol et du changement climatique sur l'hydrologie des bassins hydrographiques arctiques vont probablement modifier la quantité et la composition de matière organique dissoute (MOD) exportée. En juillet 2007, des averses intenses et l'épaississement de la couche active ont causé des décollements généralisés de la couche active à Cape Bounty, île Melville (Canada). Cette étude examine les impacts de l'hydrologie saisonnière et de la perturbation du pergélisol sur la composition de la MOD exportée des bassins versants d'amont du HautArctique. En 2012, on a échantillonné des cours d'eau de trois bassins versants perturbés et d'un bassin versant non perturbé. La composition de la MOD a été analysée en utilisant la spectroscopie à fluorescence et l'absorptiométrie. La MOD a surtout été exportée pendant la crue printanière. Pendant cette période, le bassin versant non perturbé a exporté de la MOD humifiée à haute fluorescence telle humique qui provenait probablement de ruissellement par sol riche organique mince. En revanche, la MOD exportée de bassins versants perturbés était plus fraîche, moins humifiée avec une haute proportion d'acide humique à Mots-clés : décollements de la couche active, matière organique dissoute, fluorescence, Haut-Arctique, analyse de facteurs parallèles...

show abstract

“…months to decades), thus providing a positive climate effect with respect to global warming (e.g. Cory et al, 2013Cory et al, , 2014Laurion and Mladenov, 2013). The water column rate of DOM photodegradation to CO 2 or to partially oxidized DOM increases with increasing UV radiation, and also depends on the rate of light absorption by DOM in the water column, and the lability of DOM to be converted to CO 2 or to partially oxidized DOM during light exposure.…”

Section: Photodegradation Of Organic Carbonmentioning

confidence: 99%

Reviews and syntheses: Effects of permafrost thaw on Arctic aquatic ecosystems

et al. 2015

View full text Add to dashboard Cite

Abstract. The Arctic is a water-rich region, with freshwater systems covering about 16 % of the northern permafrost landscape. Permafrost thaw creates new freshwater ecosystems, while at the same time modifying the existing lakes, streams, and rivers that are impacted by thaw. Here, we describe the current state of knowledge regarding how permafrost thaw affects lentic (still) and lotic (moving) systems, exploring the effects of both thermokarst (thawing and collapse of ice-rich permafrost) and deepening of the active layer (the surface soil layer that thaws and refreezes each year). Within thermokarst, we further differentiate between the effects of thermokarst in lowland areas vs. that on hillslopes. For almost all of the processes that we explore, the effects of thaw vary regionally, and between lake and stream systems. Much of this regional variation is caused by differences in ground ice content, topography, soil type, and permafrost coverage. Together, these modifying factors determine (i) the degree to which permafrost thaw manifests as thermokarst, (ii) whether thermokarst leads to slumping or the formation of thermokarst lakes, and (iii) the manner in which constituent delivery to freshwater systems is altered by thaw. Differences in thaw-enabled constituent delivery can Published by Copernicus Publications on behalf of the European Geosciences Union. J. E. Vonk et al.: Effects of permafrost thaw on Arctic aquatic ecosystemsbe considerable, with these modifying factors determining, for example, the balance between delivery of particulate vs. dissolved constituents, and inorganic vs. organic materials. Changes in the composition of thaw-impacted waters, coupled with changes in lake morphology, can strongly affect the physical and optical properties of thermokarst lakes. The ecology of thaw-impacted lakes and streams is also likely to change; these systems have unique microbiological communities, and show differences in respiration, primary production, and food web structure that are largely driven by differences in sediment, dissolved organic matter, and nutrient delivery. The degree to which thaw enables the delivery of dissolved vs. particulate organic matter, coupled with the composition of that organic matter and the morphology and stratification characteristics of recipient systems will play an important role in determining the balance between the release of organic matter as greenhouse gases (CO 2 and CH 4 ), its burial in sediments, and its loss downstream. The magnitude of thaw impacts on northern aquatic ecosystems is increasing, as is the prevalence of thaw-impacted lakes and streams. There is therefore an urgent need to quantify how permafrost thaw is affecting aquatic ecosystems across diverse Arctic landscapes, and the implications of this change for further climate warming.

show abstract

Dissolved organic matter photolysis in Canadian arctic thaw ponds

Cited by 74 publications

References 57 publications

Frozen ponds: production and storage of methane during the Arctic winter in a lowland tundra landscape in northern Siberia, Lena River delta

Frozen ponds: production and storage of methane during the Arctic winter in a lowland tundra landscape in northern Siberia, Lena River delta

Seasonal hydrology and permafrost disturbance impacts on dissolved organic matter composition in High Arctic headwater catchments

Reviews and syntheses: Effects of permafrost thaw on Arctic aquatic ecosystems

Contact Info

Product

Resources

About