Basin scale controls on CO<sub>2</sub> and CH<sub>4</sub> emissions from the Upper Mississippi River

Crawford, Charles G.; Loken, Luke C.; Stanley, Emily H.; Stets, Edward G.; Dornblaser, M.; Striegl, Robert G.

doi:10.1002/2015gl067599

Cited by 76 publications

(54 citation statements)

References 38 publications

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“…The main stem Mississippi River downstream of the UMR tributaries is capable of large-scale CO 2 undersaturation [Crawford et al, 2016]. These conditions may serve to inhibit in-stream degradation of OM as well as autotrophic production in tributaries, resulting in increased rates of biological activity in the main stem.…”

Section: Processing Of Carbon During Downstream Transportmentioning

confidence: 99%

Biological and land use controls on the isotopic composition of aquatic carbon in the Upper Mississippi River Basin

Voß

Wickland

Aiken

et al. 2017

Global Biogeochemical Cycles

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Riverine ecosystems receive organic matter (OM) from terrestrial sources, internally produce new OM, and biogeochemically cycle and modify organic and inorganic carbon. Major gaps remain in the understanding of the relationships between carbon sources and processing in river systems. Here we synthesize isotopic, elemental, and molecular properties of dissolved organic carbon (DOC), particulate organic carbon (POC), and dissolved inorganic carbon (DIC) in the Upper Mississippi River (UMR) system above Wabasha, MN, including the main stem Mississippi River and its four major tributaries (Minnesota, upper Mississippi, St. Croix, and Chippewa Rivers). Our goal was to elucidate how biological processing modifies the chemical and isotopic composition of aquatic carbon pools during transport downstream in a large river system with natural and man‐made impoundments. Relationships between land cover and DOC carbon‐isotope composition, absorbance, and hydrophobic acid content indicate that DOC retains terrestrial carbon source information, while the terrestrial POC signal is largely replaced by autochthonous organic matter, and DIC integrates the influence of in‐stream photosynthesis and respiration of organic matter. The UMR is slightly heterotrophic throughout the year, but pools formed by low‐head navigation dams and natural impoundments promote a shift toward autotrophic conditions, altering aquatic ecosystem dynamics and POC and DIC compositions. Such changes likely occur in all major river systems affected by low‐head dams and need to be incorporated into our understanding of inland water carbon dynamics and processes controlling CO2 emissions from rivers, as new navigation and flood control systems are planned for future river and water resources management.

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Section: Processing Of Carbon During Downstream Transportmentioning

confidence: 99%

Biological and land use controls on the isotopic composition of aquatic carbon in the Upper Mississippi River Basin

Voß

Wickland

Aiken

et al. 2017

Global Biogeochemical Cycles

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“…2; Tables S2, S3) require a cautious assessment of dam effects, the higher values of CH 4 and N 2 O measured in some dams and outflows compared to upstream levels indicate dam-specific conditions driving the production and consumption of CH 4 and N 2 O in reservoir water or sediments. Crawford et al (2016) observed a weak summer-330 time CO 2 sink due to enhanced photosynthesis but elevated concentrations and fluxes of CH 4 along the upper Mississippi River reaches impounded by a series of low-head dams. They attributed the observed supersaturation in CH 4 to anaerobic conditions in organic-rich sediments.…”

Section: Spatial Variations In Three Ghgs Observed Along the Middle Rmentioning

confidence: 99%

“…The trapping 70 of sediments and nutrients in reservoir sediments, combined with increased water retention time and improved light conditions promoting primary production, can alter significantly the rate of production and consumption of CO 2 and CH 4 in impounded waters (Maavara et al, 2017). Many studies have examined impoundment effects on GHG emissions from various types and sizes of dams including hydroelectric dams, often reporting contrasting results such as large pulse emissions of CO 2 and CH 4 from the flooded vegetation and sediments following dam construction and an enhanced primary production and CO 2 sink in 75 eutrophic reservoirs (Abril et al, 2005;Chen et al, 2009;Barros et al, 2011;Hu and Cheng, 2013;Maeck et al, 2013;Crawford et al, 2016;Maavara et al, 2017;Shi et al, 2017). These contrasting impoundment effects can be explained by the shifting balance between autotrophy and heterotrophy at diel to decadal timescales (Park et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…Measurements of multiple GHGs in highly human-impacted river systems have provided drastically different pictures of the longitudinal and seasonal patterns of GHGs from those observed in large natural rivers (Silvennoinen et al, 2008;Burgos et al, 2015;Crawford et al, 2016;Smith et al, 2017;Wang et al, 2017b). A growing number of dams constructed on rivers worldwide have altered riverine flows of water and materials to the oceans, trapping over 100 billion metric tons of sediment and up to 3 billion metric tons of C in the reservoirs constructed over the last five decades (Syvitski et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

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Longitudinal discontinuities in riverine greenhouse gas dynamics generated by dams and urban wastewater

Jin¹,

Yoon²,

Begum³

et al. 2018

Preprint

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Abstract.Riverine emissions of CO 2 and other greenhouse gases (GHGs) represent crucial, but poorly constrained components of the global GHG budgets. Three major GHGs -CO 2 , CH 4 , and N 2 O -have rarely been measured simultaneously in river systems modified by human activities, adding uncertainties to the estimates of global riverine GHG emissions. Measurements of C isotopes in dissolved organic carbon (DOC), CO 2 , and CH 4 were combined with basin-wide surveys of three GHGs in the Han 15 River, South Korea to investigate the effects of dams and urban water pollution as primary controls on GHG dynamics in the highly human-impacted river basin with a population >25 million. Monthly monitoring and two-season comparison were conducted at 6 and 15 sites, respectively, to measure surface water concentrations of three GHGs, along with DOC and its optical properties. The basin-wide surveys were complemented with a boat cruise along the lower reach and synoptic samplings along a polluted tributary delivering effluents from a large wastewater treatment plant (WWTP) to the lower reach. The basin-20 wide surveys of three GHGs revealed distinct increases in the concentrations of three gases along the lower reach receiving urban tributaries enriched in GHGs and DOC. Compared to the spatial patterns of GHGs observed in the upper and lower reaches, the levels of pCO 2 were consistently lower across the impounded middle reach, whereas concentrations of CH 4 and N 2 O were relatively high in some impoundment-affected sites. Similar levels and temporal variations in three GHGs at the WWTP effluents and the receiving tributary indicated a disproportionate contribution of the WWTP to the tributary exports of 25 DOC and GHGs. Measurements of δ 13 C in surface water CO 2 and CH 4 sampled during the cruise along the lower reach, combined with δ 13 C and Δ 14 C in dissolved organic matter (DOM) sampled across the basin, implied that longitudinal decreases in Δ 14 C in DOM mighte be associated with wastewater-derived, old DOM in urban tributaries, which, together with enhanced photosynthesis and CH 4 oxidation in the eutrophic lower reach, appear to constrain downstream changes in δ 13 C in CO 2 and CH 4 . The overall results suggest that dams and urban wastewater may create longitudinal discontinuities in riverine metabolic 30 processes leading to large spatial variations in three GHGs. Further research is required to evaluate the relative contributions Biogeosciences Discuss., https://doi

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“…In extreme cases of wastewater pollution, anoxic conditions will lead to low N 2 O levels due to denitrification (Rajkumar et al, 2008), but in oxic conditions nitrification fuelled by NH 4 + inputs from wastewater leads to N 2 O production (Garnier et al, 2009;Yu et al, 2013;Marwick et al, 2014). Impoundments increase water residence time that favour organic matter sedimentation and CH 4 production (Maeck et al, 2013;Crawford et al, 2016). Increased water residence time and water transparency due to impoundments can lead to low CO 2 levels related to enhanced primary production .…”

Section: Introductionmentioning

confidence: 99%

Effects of agricultural land use on fluvial carbon dioxide, methane and nitrous oxide concentrations in a large European river, the Meuse (Belgium)

Borges

Darchambeau

Lambert

et al. 2018

Science of The Total Environment

161

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• Large data-set of CO 2 , CH 4 , and N 2 O in the surface waters of the Meuse River We report a data-set of CO 2 , CH 4 , and N 2 O concentrations in the surface waters of the Meuse river network in Belgium, obtained during four surveys covering 50 stations (summer 2013 and late winter 2013, 2014 and 2015), from yearly cycles in four rivers of variable size and catchment land cover, and from 111 groundwater samples. Surface waters of the Meuse river network were over-saturated in CO 2 , CH 4 , N 2 O with respect to atmospheric equilibrium, acting as sources of these greenhouse gases to the atmosphere, although the dissolved gases also showed marked seasonal and spatial variations. Seasonal variations were related to changes in freshwater discharge following the hydrological cycle, with highest concentrations of CO 2 , CH 4 , N 2 O during low water owing to a longer water residence time and lower currents (i.e. lower gas transfer velocities), both contributing to the accumulation of gases in the water column, combined with higher temperatures favourable to microbial processes. Inter-annual differences of discharge also led to differences in CH 4 and N 2 O that were higher in years with prolonged low water periods. Spatial variations were mostly due to differences in land cover over the catchments, with systems dominated by agriculture (croplands and pastures) having higher CO 2 , CH 4 , N 2 O levels than forested systems. This seemed to be related to higher levels of dissolved and particulate organic matter, as well as dissolved inorganic nitrogen in agriculture dominated systems compared to forested ones. Groundwater had very low CH 4 concentrations in the shallow and unconfined aquifers (mostly fractured limestones) of the Contents lists available at ScienceDirectScience of the Total Environment j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / s c i t o t e n vMeuse basin, hence, should not contribute significantly to the high CH 4 levels in surface riverine waters. Owing to high dissolved concentrations, groundwater could potentially transfer important quantities of CO 2 and N 2 O to surface waters of the Meuse basin, although this hypothesis remains to be tested.

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Basin scale controls on CO₂ and CH₄ emissions from the Upper Mississippi River

Cited by 76 publications

References 38 publications

Biological and land use controls on the isotopic composition of aquatic carbon in the Upper Mississippi River Basin

Biological and land use controls on the isotopic composition of aquatic carbon in the Upper Mississippi River Basin

Longitudinal discontinuities in riverine greenhouse gas dynamics generated by dams and urban wastewater

Effects of agricultural land use on fluvial carbon dioxide, methane and nitrous oxide concentrations in a large European river, the Meuse (Belgium)

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Basin scale controls on CO2 and CH4 emissions from the Upper Mississippi River

Cited by 76 publications

References 38 publications

Biological and land use controls on the isotopic composition of aquatic carbon in the Upper Mississippi River Basin

Biological and land use controls on the isotopic composition of aquatic carbon in the Upper Mississippi River Basin

Longitudinal discontinuities in riverine greenhouse gas dynamics generated by dams and urban wastewater

Effects of agricultural land use on fluvial carbon dioxide, methane and nitrous oxide concentrations in a large European river, the Meuse (Belgium)

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Basin scale controls on CO₂ and CH₄ emissions from the Upper Mississippi River