Photodegradation of river dissolved organic matter and trace metals in the largest European Arctic estuary

Chupakova, Anna A.; Chupakov, Artem V.; Neverova, Natalia; Shirokova, Liudmila S.; Pokrovsky, Oleg S.

doi:10.1016/j.scitotenv.2017.12.030

Cited by 33 publications

(56 citation statements)

References 90 publications

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“…The dominance of photolytic processes in DOM processing in arctic waters was reported for N America (Cory et al, 2014;Ward et al, 2017), Canadian surface waters of the temperate zone (Winter et al, 2007;Porcal et al, 2013Porcal et al, , 2014Porcal et al, , 2015, and small Swedish humic-rich headwater catchments (Köhler et al, 2002). In contrast, several other studies from Scandinavia (Groeneveld et al, 2016;Koehler et al, 2014), Canada (Laurion and Mladenov, 2013;Gareis and Lesack, 2018) and NW Russia (Oleinikova et al, 2017;Chupakova et al, 2018) demonstrated sizeable removal of colored Biogeosciences Discuss., https://doi.org/10.5194/bg-2018-528 Manuscript under review for journal Biogeosciences Discussion started: 14 January 2019 c Author(s) 2019. CC BY 4.0 License.…”

Section: Introductionmentioning

confidence: 69%

“…Note that the 0.22 µm sterile filtration is the only way of conducting photodegradation experiments, given that the autoclave sterilization of DOM-rich natural water would coagulate humic material and thus is not suitable (Andresson et al, 2018). In this regard, we followed conventional methodology in this field which is exposure of 0.2 µm-sterile filtered samples in quartz reactors in the outdoor pool (Vähätalo et al, 2003;Chupakova et al, 2018;Gareis and Lesack, 2018), solar simulator (Lou and Xie, 2006;Amado et al, 2014) or directly in the lake water (Laurion and Mladenov, 2013;Groeneveld et al, 2016).…”

Section: Photodegradationmentioning

confidence: 99%

“…The day light intensity was typically between 5,000 and 20,000 lux (in average 10,000 lux or 145 W/m²) which is within the range of solar radiation at the latitude of the polar circle in the end of July -beginning of August. We have chosen 4 weeks exposure time for consistency with biodegradation experiments described above and following the previous studies on photodegradation under sunlight, which is typically from 15 to 70 days (Moran et al, 2000;Vähätalo and Wetzel, 2004;Mostofa et al, 2007;Helms et al, 2008;Chupakova et al, 2018). Dark control experiments were conducted in duplicates, using sterilized glass tubes filled by sterile 0.22 µm-filtered water, wrapped in Al foil and placed in the same outdoor pool as the experiments.…”

Section: Photodegradationmentioning

confidence: 99%

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Humic surface waters of frozen peat bogs (permafrost zone) are highly resistant to bio- and photodegradation

Shirokova¹,

Chupakov²,

Zabelina³

et al. 2019

Preprint

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Abstract. Bio- and photo-degradation of dissolved organic matter (DOM) is identified as dominant vector of C cycle in boreal and high-latitude surface waters. In contrast to large number of studies of humic waters from permafrost-free regions and oligotrophic waters from permafrost-bearing regions, the bio- and photo-lability of DOM from humic surface waters of permafrost-bearing regions has not been thoroughly evaluated. Following standardized methods, we measured biodegradation (low, intermediate, high temperature) and photodegradation (one intermediate temperature) of DOM in surface waters along the hydrological continuum (depression &#8594; stream &#8594; thermokarst lake &#8594; river Pechora) within a European Russian frozen peatland. In all systems, there was no measurable (&#8805;&#8201;10&#8201;%) bio- or photodegradation of DOM over 1 month of incubation. It is possible that the main cause of the lack of degradation is the dominance of allochthonous refractory (soil, peat) DOM in all studied waters. Yet, all surface waters were supersaturated with CO2. Thus, this study suggest that, rather than bio- and photo-degradation of DOM in the water column, other factors such as peat porewater DOM processing and respiration of sediments are the main drivers of elevated pCO2 and emission in humic boreal waters of frozen peat bogs.

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Section: Introductionmentioning

confidence: 69%

Section: Photodegradationmentioning

confidence: 99%

Section: Photodegradationmentioning

confidence: 99%

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Humic surface waters of frozen peat bogs (permafrost zone) are highly resistant to bio- and photodegradation

Shirokova¹,

Chupakov²,

Zabelina³

et al. 2019

Preprint

Self Cite

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show abstract

“…Nevertheless, it should be kept in mind that DOM optical properties during estuarine mixing might also change without changes (losses or gains) in their quantities. In addition, DOM optical properties can be affected not only by DOM concentration and composition but also by the interactions of DOM with trace metals (Sharpless & Blough, ; Xu et al, ; Yan et al, ), and estuarine mixing zones are known for supporting losses of both trace elements and DOM (Chupakova et al, ; Fichot et al, ; Hedges et al, ; Opsahl & Benner, ). The different environmental factors in different same‐salinity patches, such as pH, may also influence the DOM abundance and chemical properties (Xu et al, ) and, consequently, have a potential influence on the fate of DOM during the estuarine mixing and offshore transport.…”

Section: Discussionmentioning

confidence: 99%

“…Journal of Geophysical Research: Oceans the interactions of DOM with trace metals (Sharpless & Blough, 2014;Yan et al, 2013), and estuarine mixing zones are known for supporting losses of both trace elements and DOM (Chupakova et al, 2018;Fichot et al, 2014;Hedges et al, 1997;Opsahl & Benner, 1997). The different environmental factors in different same-salinity patches, such as pH, may also influence the DOM abundance and chemical properties and, consequently, have a potential influence on the fate of DOM during the estuarine mixing and offshore transport.…”

Section: 1029/2018jc014731mentioning

confidence: 99%

Elucidating the Hidden Nonconservative Behavior of DOM in Large River‐Dominated Estuarine and Coastal Environments

Gao

Zong

et al. 2019

JGR Oceans

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Understanding the mixing behavior and biogeochemical cycling of heterogeneous dissolved organic matter (DOM) at the land‐ocean interface has been a major challenge, especially in large river‐dominated estuarine and coastal environments with multiple and complex end‐members of riverwater and seawater. Significant correlations and thus an “apparent” conservative behavior are generally observed for the bulk DOM when plotting concentration‐salinity relationships, but the relatively small deviations from the apparent conservative behavior are difficult to be quantified. In July 2016, the flood in the Changjiang River basin caused the Changjiang Diluted Water extended widely to the western East China Sea, making it a natural laboratory to examine the river‐sea mixing behavior of riverine DOM and other optical properties. Here a new biogeochemical approach was established to elucidate their hidden nonconservative behavior in the study area. Comparisons in the bulk dissolved organic carbon and the three chromophoric DOM properties among 13 pairs of same‐salinity patches (with similar salinities but quite different distances from the river mouth) revealed that the East China Sea shelf was a significant sink for all the three chromophoric DOM properties. The Changjiang Diluted Water surface branches transporting southward tended to serve as a sink for the bulk dissolved organic carbon while the ones transporting northward were less a sink or even a source. The different removal extents of various biogeochemical constituents can also be calculated from the same‐salinity patch comparisons. Our results obtained by the new approach provide detailed magnitudes of sink or source for different DOM properties and their in situ removal/production extents, giving new insights into biogeochemical processes in large river‐dominated estuarine and coastal environments.

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Biological and photochemical reactivity of dissolved organic matter in a large temperate river

Maisonneuve

Guillemette

Lapierre

2022

Limnology & Oceanography

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Large rivers are critical conduits from continents to oceans as they receive, produce and process huge amounts of dissolved organic matter (DOM). Yet, the relative influence of intrinsic DOM properties and extrinsic environmental properties on these processes at the ecosystem‐level is rarely studied. We assessed DOM optical properties as well as bioreactivity and photoreactivity at 40 sites along a >200 km transect of the freshwater portion of the St. Lawrence River through a series of standardized microbial incubations and exposure to simulated sunlight, and then estimated in situ areal rates of processing. We found that biological and photochemical processes preferentially targeted contrasting pools of DOM, but that DOM composition had an undiscernible effect on in situ degradation rates compared to other environmental factors. Total daily processing across the whole water column ranged from 36.7 to 892.1 mg C m−2. In situ photochemical degradation was largely driven by intrinsic DOM photoreactivity rather than environmental drivers in the water. In contrast, we found a relatively constant baseline pool of biolabile DOM that appeared to be independent from changes in concentration and environmental conditions. In situ DOM processing was mostly driven by biological degradation (on average 95%), and disproportionately high biodegradation rates (2.5–4x the average) were found in a few shallower sites near effluents or islands, potentially driven by local increases in nutrient concentration and in the proportion of protein‐like DOM. These results illustrate how DOM composition and degradability interact with ambient environmental and morphological properties to dictate an ecosystem‐level reactivity of DOM.

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Photodegradation of river dissolved organic matter and trace metals in the largest European Arctic estuary

Cited by 33 publications

References 90 publications

Humic surface waters of frozen peat bogs (permafrost zone) are highly resistant to bio- and photodegradation

Humic surface waters of frozen peat bogs (permafrost zone) are highly resistant to bio- and photodegradation

Elucidating the Hidden Nonconservative Behavior of DOM in Large River‐Dominated Estuarine and Coastal Environments

Biological and photochemical reactivity of dissolved organic matter in a large temperate river

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