Variations of total dissolved iron and its impacts during an extreme spring flooding event in the Songhua River

Guan, Jiunian; Yan, Baixing; Yuan, Xing

doi:10.1016/j.gexplo.2016.04.003

Cited by 10 publications

(3 citation statements)

References 56 publications

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“…Moreover, both DOC and dFe concentrations in the large rivers during snowmelt season had the highest values in the year, similarly to those in the Sofron River, strongly indicating that snowmelt season is the most important period for transporting large amounts of DOC and dFe. Elevated dFe concentrations during snowmelt season were also observed in large tributaries of the Amur River [45,46], and other boreal rivers [39][40][41]47]. To our knowledge, the present study is the first to corroborate this large-scale dFe transport that resulted from the high dFe concentrations in the uppermost soil pore waters.…”

Section: Dfe Production In Uppermost Soils and Its Discharge Into Rivsupporting

confidence: 74%

Seasonal Variations of Dissolved Iron Concentration in Active Layer and Rivers in Permafrost Areas, Russian Far East

Tashiro

Yoh

Shiraiwa

et al. 2020

Water

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Dissolved iron (dFe) in boreal rivers may play an important role in primary production in high-latitude oceans. However, iron behavior in soils and dFe discharge mechanism from soil to the rivers are poorly understood. To better understand iron dynamics on the watershed scale, we observed the seasonal changes in dFe and Dissolved Organic Carbon (DOC) concentrations in the river as well as dFe concentration in soil pore waters in permafrost watershed from May to October. During snowmelt season, high dFe production (1.38–4.70 mg L−1) was observed in surface soil pore waters. Correspondingly, riverine dFe and DOC concentrations increased to 1.10 mg L−1 and 32.3 mg L−1, and both were the highest in the year. After spring floods, riverine dFe and DOC concentrations decreased to 0.15 mg L−1 and 7.62 mg L−1, and dFe concentration in surface soil pore waters also decreased to 0.20–1.28 mg L−1. In late July, riverine dFe and DOC concentrations increased to 0.33 mg L−1 and 23.6 mg L−1 in response to heavy rainfall. In August and September, considerable increases in dFe concentrations (2.00–6.90 mg L−1) were observed in subsurface soil pore waters, probably because infiltrated rainwater developed reducing conditions. This dFe production was confirmed widely in permafrost wetlands in valley areas. Overall, permafrost wetlands in valley areas are hotspots of dFe production and greatly contribute to dFe and DOC discharge to rivers, especially during snowmelt and rainy seasons.

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Section: Dfe Production In Uppermost Soils and Its Discharge Into Rivsupporting

confidence: 74%

Seasonal Variations of Dissolved Iron Concentration in Active Layer and Rivers in Permafrost Areas, Russian Far East

Tashiro

Yoh

Shiraiwa

et al. 2020

Water

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“…The majority of DFe in the Amur River occurs in organic complex forms, as indicated by the strong correlation between organic matter and DFe (Wang et al, 2012). Likewise, DOC and DFe concentrations increased concurrently during this extreme event; a similar relationship was also observed in different rivers, indicating that DOM may be the main carrier of DFe during the flooding process (Wen et al, 2008;Jiann et al, 2013;Guan et al, 2015b;2016b).…”

Section: Origins Of Dfe During Extreme Flood Eventmentioning

confidence: 82%

Variations of dissolved iron in the Amur River during an extreme flood event in 2013

et al. 2016

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As a key factor limiting primary productivity in marine ecosystem, dissolved iron (DFe) export from fluvial systems has increased recently. There is particular concern about discharges of DFe during extreme flooding, when they are thought to increase considerably. An extreme flood event that caused inundation of extensive areas of Far Eastern Russia and Northeastern China occurred in the basin of the Amur River during summer and autumn 2013. During this event, water samples were collected in the middle reaches of the Amur River and the lower reaches at Khabarovsk City and analyzed for DFe concentrations and other aquatic parameters. The results show that the average DFe concentrations in the middle reaches of the Amur River (right bank) and at Khabarovsk were 1.11 mg/L and 0.32 mg/L, respectively, during the extreme flood in 2013. The total discharge of DFe during the flood event was 6.25 × 10 4 t. The high discharge of DFe during the flood reflects the elevated discharge of the river, hydrologically connected riparian wetlands, vast quantities of terrestrial runoff, and flood discharges from the Zeya and Bureya reservoirs. These results show that long-term monitoring is needed to identify and assess the impacts of DFe transport on the downstream reaches, estuarine area, and coastal ecosystems of the Amur River.

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“…For example, increased oxygen consumption has been observed in headwater streams during elevated flow, and interpreted as microbial respiration as a result of lateral export of bioavailable DOM (e.g., Demars, 2019). However, it is also recognized that during high discharge, concentrations of oxygen sensitive species such as dissolved iron can rise in surface waters, being mobilized from saturated water of anoxic soils (Björnerås et al, 2017; Guan et al, 2016; Knorr, 2013) and these may rapidly react with dissolved oxygen.…”

Section: Discussionmentioning

confidence: 99%

Particles and Aeration at Mire‐Stream Interfaces Cause Selective Removal and Modification of Dissolved Organic Matter

et al. 2020

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Peatlands are dominant sources of dissolved organic matter (DOM) to boreal inland waters and play important roles in the aquatic carbon cycle. Yet before peat-derived DOM enters aquatic networks, it needs to pass through peat-stream interfaces that are often characterized by transitions from anoxic or hypoxic to oxic conditions. Aeration at these interfaces may trigger processes that impact the DOM pool, and its fate downstream. Here we experimentally assessed how the aeration of iron-and organic-rich mire-waters influences biodegradation, particle-formation, and modification of DOM. In addition, we investigated how suspended peat-derived particles from mires may influence these processes. We found that within 5 days of aeration, 20% of the DOM transformed into particulate organic matter (POM). This removal was likely due to combination of mechanisms including coprecipitation with oxidized iron, aggregation, and DOM-adsorption onto peat-derived particles. Peat-derived particles promoted microbial activity, but biodegradation was a minor loss mechanism of DOM removal. Interestingly, microbial respiration accounted for only half of the oxygen loss, suggesting substantial nonrespiratory oxygen consumption. The differences observed in DOM characteristics between anoxic and aerated treatments suggest that hydrophilic, aromatic DOM coprecipitated with iron oxides in aerated samples, and the corresponding C:N analysis of generated POM revealed that these organic species were nitrogen-poor. Meanwhile, POM formed via adsorption onto peat-derived particles generated from nonaromatic DOM and more nitrogen-rich species. Hence, selective removal of DOM, dissolved iron, and thus oxygen may be important and overlooked processes in mire-dominated headwater systems. Plain Language Summary Substantial amounts of dissolved organic matter are discharged from boreal peatlands into small streams and delivered to downstream rivers and lakes, impacting water quality, freshwater ecology, and the aquatic carbon cycle. About half of this dissolved organic matter is processed and removed during downstream transport, mainly via degradation and CO 2 emission, but also through particle formation and sedimentation. Less is known about the processing in upstream systems, where peat-water emerges into small streams. These peat-stream interfaces are characterized by rapid transitions from anoxic to oxic conditions. Since oxygen exposure may promote both microbial activity and chemical reactions, e.g., coprecipitation with iron, these interfaces might be critical locations for dissolved organic matter transformations. Here we experimentally study microbial and nonbiological processing of dissolved organic matter when anoxic mire-waters are aerated. We also assess how particles found in the peat-water may stimulate these processes. Our results suggest significant nonbiological particle formation and modification of the dissolved organic matter pool when anoxic waters from peatlands are first delivered to streams. In addition, we find that natural pa...

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Variations of total dissolved iron and its impacts during an extreme spring flooding event in the Songhua River

Cited by 10 publications

References 56 publications

Seasonal Variations of Dissolved Iron Concentration in Active Layer and Rivers in Permafrost Areas, Russian Far East

Seasonal Variations of Dissolved Iron Concentration in Active Layer and Rivers in Permafrost Areas, Russian Far East

Variations of dissolved iron in the Amur River during an extreme flood event in 2013

Particles and Aeration at Mire‐Stream Interfaces Cause Selective Removal and Modification of Dissolved Organic Matter

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