Effect of chromophoric dissolved organic matter on epilimnetic stratification in lakes

Caplanne, Sophie; Laurion, Isabelle

doi:10.1007/s00027-007-7006-0

Cited by 44 publications

(37 citation statements)

References 58 publications

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“…While aromatic DOC typically generates less bacterial activity than aliphatic DOC [Amon and Benner, 1996], humic substances are highly susceptible to degradation and mineralization by photochemical reactions [Allard et al, 1994]. Shading by photoreactive DOC can influence rates of primary production and impact thermal stratification in water bodies [Caplanne and Laurion, 2008]. Our study shows that agricultural fields can contribute disproportionately large amounts of DOC to watershed runoff during stormflow, with a significant labile and photoreactive fraction that can be ecologically significant downstream.…”

mentioning

confidence: 78%

“…Relative to watersheds vegetated with uncultivated plant species, agricultural watersheds export structurally complex DOC with larger aromatic fractions [Graeber et al, 2012], although composition varies temporally as dominant flow paths change [Hernes et al, 2008;Vidon et al, 2008]. Highly aromatic DOC is typically derived from leaching of upper humus-rich soil horizons, and it can affect ecosystem functioning by decreasing primary production through shading [Carpenter et al, 1998], influencing thermal stratification of water bodies [Caplanne and Laurion, 2008], and providing labile carbon compounds for microbial uptake [Moran and Zepp, 1997].…”

Section: Introductionmentioning

confidence: 99%

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Dissolved and particulate organic carbon fluxes from an agricultural watershed during consecutive tropical storms

Caverly

Kaste

Hancock

et al. 2013

Geophysical Research Letters

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[1] Low-frequency high-magnitude hydrologic events mobilize a disproportionate amount of dissolved organic carbon (DOC) from watersheds, but few studies measure the role of extreme storms in exporting organic carbon from croplands. We use high-resolution measurements of storm runoff to quantify DOC and particulate organic carbon (POC) fluxes from an agricultural field during consecutive tropical storms that delivered 41 cm of rainfall to the Virginia Coastal Plain. Over a 2 week period, we measured exports of 22 kg DOC ha À1 and 11.3 kg POC ha À1. Ultraviolet absorbance measurements indicate that the aromatic DOC fraction systematically increased as plant-derived aliphatic carbon was depleted during the initial event. Croplands can have event-scale carbon losses that equal or exceed published estimates of annual export for perennial streams draining forested and mixed land use watersheds. We quantify aromatic DOC fractions approaching 50%, indicating that agricultural stormflow can produce a significant load of relatively photoreactive carbon. Citation: Caverly, E., J. M. Kaste, G. S. Hancock, and R. M. Chambers (2013), Dissolved and particulate organic carbon fluxes from an agricultural watershed during consecutive tropical storms, Geophys. Res. Lett., 40,[5147][5148][5149][5150][5151][5152]

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mentioning

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Dissolved and particulate organic carbon fluxes from an agricultural watershed during consecutive tropical storms

Caverly

Kaste

Hancock

et al. 2013

Geophysical Research Letters

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“…2; Gareis et al, 2010;Morris et al, 1995) demonstrate that CDOM was the main UV and visible (PAR) light absorbing constituent in surface waters across the Arctic. Because UV and PAR account for approximately 51 % of the energy within the shortwave radiation portion of the spectrum (300-2500 nm), absorption of sunlight by CDOM contributes to the frequency and extent of stratification by restricting warming to the surface layers (Caplanne and Laurion, 2008;.…”

Section: Stratification In Beaded Streamsmentioning

confidence: 99%

Controls on dissolved organic matter (DOM) degradation in a headwater stream: the influence of photochemical and hydrological conditions in determining light-limitation or substrate-limitation of photo-degradation

et al. 2015

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Abstract. We investigated how absorption of sunlight by chromophoric dissolved organic matter (CDOM) controls the degradation and export of DOM from Imnavait Creek, a beaded stream in the Alaskan Arctic. We measured concentrations of dissolved organic carbon (DOC), as well as concentrations and characteristics of CDOM and fluorescent dissolved organic matter (FDOM), during ice-free periods of 2011-2012 in the pools of Imnavait Creek and in soil waters draining to the creek. Spatial and temporal patterns in CDOM and FDOM in Imnavait Creek were analyzed in conjunction with measures of DOM degradation by sunlight and bacteria and assessments of hydrologic residence times and in situ UV exposure. CDOM was the dominant light attenuating constituent in the UV and visible portion of the solar spectrum, with high attenuation coefficients ranging from 86 ± 12 m −1 at 305 nm to 3 ± 1 m −1 in the photosynthetically active region (PAR). High rates of light absorption and thus light attenuation by CDOM contributed to thermal stratification in the majority of pools in Imnavait Creek under low-flow conditions. In turn, thermal stratification increased the residence time of water and DOM, and resulted in a separation of water masses distinguished by contrasting UV exposure (i.e., UV attenuation by CDOM with depth resulted in bottom waters receiving less UV than surface waters). When the pools in Imnavait Creek were stratified, DOM in the pool bottom water closely resembled soil water DOM in character, while the concentration and character of DOM in surface water was reproduced by experimental photo-degradation of bottom water. These results, in combination with water column rates of DOM degradation by sunlight and bacteria, suggest that photo-degradation is the dominant process controlling DOM fate and export in Imnavait Creek. A conceptual model is presented showing how CDOM amount and lability interact with incident UV light and water residence time to determine whether photo-degradation is "light-limited" or "substrate-limited". We suggest that degradation of DOM in CDOM-rich streams or ponds similar to Imnavait is typically light-limited under most flow conditions. Thus, export of DOM from this stream will be less under conditions that increase the light available for DOM photo-degradation (i.e., low flows, sunny days).

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“…perature regimes through its absorption of sunlight (Caplanne and Laurion, 2008), and with suspended particles, they contribute to form a distinct and stabile thermocline (Laurion et al, 2010). The rate of DOM input to aquatic systems has been documented to increase in boreal lakes over the last decades (Hudson et al, 2003), and while no such information is yet available for thaw ponds, the recent mobilization of terrestrial carbon stocks stored for thousands of years in the permafrost (Vonk et al, 2012) suggests a similar DOM increase is taking place also in the north.…”

Section: T Roiha Et Al: Carbon Dynamics In Highly Heterotrophic Submentioning

confidence: 99%

Carbon dynamics in highly heterotrophic subarctic thaw ponds

Roiha

Laurion²,

Rautio

2015

Biogeosciences

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Abstract. Global warming has accelerated the formation of permafrost thaw ponds in several subarctic and arctic regions. These ponds are net heterotrophic as evidenced by their greenhouse gas (GHG) supersaturation levels (CO 2 and CH 4 ), and generally receive large terrestrial carbon inputs from the thawing and eroding permafrost. We measured seasonal and vertical variations in the concentration and type of dissolved organic matter (DOM) in five subarctic thaw (thermokarst) ponds in northern Quebec, and explored how environmental gradients influenced heterotrophic and phototrophic biomass and productivity. Late winter DOM had low aromaticity indicating reduced inputs of terrestrial carbon, while the high concentration of dissolved organic carbon (DOC) suggests that some production of nonchromophoric dissolved compounds by the microbial food web took place under the ice cover. Summer DOM had a strong terrestrial signature, but was also characterized with significant inputs of algal-derived carbon, especially at the pond surface. During late winter, bacterial production was low (maximum of 0.8 mg C m −3 d −1 ) and was largely based on free-living bacterioplankton (58 %). Bacterial production in summer was high (up to 58 mg C m −3 d −1 ), dominated by particle-attached bacteria (67 %), and strongly correlated with the amount of terrestrial carbon. Primary production was restricted to summer surface waters due to strong light limitation deeper in the water column or in winter. The phototrophic biomass was equal to the heterotrophic biomass, but as the algae were mostly composed of mixotrophic species, most probably they used bacteria rather than solar energy in such shaded ponds. Our results point to a strong heterotrophic energy pathway in these thaw pond ecosystems, where bacterioplankton dominates the production of new carbon biomass in both summer and winter.

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Effect of chromophoric dissolved organic matter on epilimnetic stratification in lakes

Cited by 44 publications

References 58 publications

Dissolved and particulate organic carbon fluxes from an agricultural watershed during consecutive tropical storms

Dissolved and particulate organic carbon fluxes from an agricultural watershed during consecutive tropical storms

Controls on dissolved organic matter (DOM) degradation in a headwater stream: the influence of photochemical and hydrological conditions in determining light-limitation or substrate-limitation of photo-degradation

Carbon dynamics in highly heterotrophic subarctic thaw ponds

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