Seasonal changes in the sources and fluxes of dissolved inorganic carbon through the St. Lawrence River—isotopic and chemical constraint

Hélie, Jean‐François; Hillaire‐Marcel, Claude; Rondeau, Bernard

doi:10.1016/s0009-2541(01)00417-x

Cited by 136 publications

(90 citation statements)

References 16 publications

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“…Carbon dioxide saturation of stream waters in our study exceeded the levels of saturation reported from larger rivers, such as the Amazon (Stallard & Edmond, 1987), Lena (Huh et al, 1998), Thames (Neal, Harrow, & Williams, 1998), Hudson (Raymond, Caraco, & Cole, 1997), St. Lawrence (Hélie, Hillaire-Marcel, & Rondeau, 2002), and Niger Rivers (Martins & Probst, 1991) and from smaller rivers in the United Kingdom (Neal, House et al, 1998) and Spain (Pinol & Avila, 1992). In those studies, river water usually was no more than 5-20 times supersaturated, although some of the small rivers in Spain were as much as 55 times supersaturated (Pinol & Avila, 1992).…”

Section: Urban Land Cover and Stream Chemistrycontrasting

confidence: 64%

Urban Influences on Stream Chemistry and Biology in the Big Brushy Creek Watershed, South Carolina

Lewis

Mitchell

Andersen

et al. 2007

Water Air Soil Pollut

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Naturally high total dissolved solids and upstream agricultural runoff often mask the influence of urban land cover on stream chemistry and biology. We examined the influence of headwater urbanization on the water chemistry, microbiology, and fish communities of the Big Brushy Creek watershed, a 96 km 2 drainage basin in the piedmont of South Carolina, USA. Concentrations of most major anions and cations (especially nitrate, sulfate, chloride, sodium, potassium, and calcium) were highest in the urban headwaters and decreased downstream. Generally, the highest concentrations of suspended coliform bacteria occurred in the urban headwaters. In contrast, stream habitat quality and the abundance, species richness, and species diversity of fishes did not differ significantly between urban and rural sites. Discharge of wastewater treatment plant effluent at one rural location caused an increase in concentrations of many solutes and possibly the abundance of benthic algae. We hypothesize that atmospheric dry deposition and domestic animal wastes are important sources of stream solutes and of coliform bacteria, respectively, in the urban headwaters. The lack of significant differences in fish abundance and diversity between urban and rural sites may indicate that urban development in the Big Brushy Creek watershed has not yet degraded habitat conditions greatly for stream fishes. Alternatively, agriculture or other land uses may have degraded stream habitat quality throughout the watershed prior to urbanization.

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Section: Urban Land Cover and Stream Chemistrycontrasting

confidence: 64%

Urban Influences on Stream Chemistry and Biology in the Big Brushy Creek Watershed, South Carolina

Lewis

Mitchell

Andersen

et al. 2007

Water Air Soil Pollut

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“…High area-specific C export values ([4000 kg C km -2 year -1 ) are typical of humic waters of large northern Québec rivers draining the boreal forest on the Pre-Cambrian Shield (Hudon et al 1996;Clair et al 2013), but may also be observed in heavily farmed watersheds (this study). At Québec, mean DOC annual exports (1.39 9 10 6 t C year -1 , Table 4) from our study were about 4 times smaller than dissolved inorganic carbon (DIC) flux (5.94-6.85 9 10 6 t C year -1 (1998 data, Hélie et al 2002); our focus on the DOC compartment was justified in view of its eventual degradation in deep estuarine waters.…”

Section: Discussionmentioning

confidence: 59%

Hydrological and biological processes modulate carbon, nitrogen and phosphorus flux from the St. Lawrence River to its estuary (Quebec, Canada)

et al. 2017

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Increased flux of carbon and nutrients from human activities in river basins were linked to acidification and deepwater hypoxia in estuaries and coastal areas worldwide. Annual loads (1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011) of suspended particulate matter (SPM), dissolved organic carbon (DOC), total nitrogen (TN) and total phosphorus (TP) were assessed at the Lake Ontario inlet of the St. Lawrence River (SLR) (7110 m 3 s -1 ) and its estuarine outlet at Québec City (12,090 m 3 s -1 ). Internal loads from the Ottawa River (1950 m 3 s -1 ), seventeen other tributaries, urban wastewaters, atmospheric deposition and erosion were also estimated. Erosion (65% of SPM, 29% of TP), inflow from Lake Ontario (42% of DOC, 47% of TN) and Ottawa River (28% of DOC) contributed important flux to the estuary. Loads from other tributaries (20 and 27% of TN and TP at Quebec City) largely exceeded municipal sources (6% of exported TN and TP) and require future remediation. Aquatic plants fixed 277,000 t of C, 49,000 t of N and 7000 t of P (May-Sept.), delaying the nutrient flux to the estuary and turning the SLR into a nutrient sink over summers of lowest discharge. Degradation of exported organic C could consume 5.4-7.1 million t O 2 year -1 in the estuary whereas SLR flux of N and P represent 31-47% and 7-14% of total annual estuarine flux, respectively. Carbon and Nitrogen flux from freshwaters partly explain the decline in pH and oxygen concentrations in deep estuarine waters thus highlighting the need to reduce diffuse sources of nutrients in the entire watershed.

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“…The erosion of the carbonate rocks of the drainage basin is practically constant, as the quantity of bicarbonate ions carried by the river varies little from season to season (Pelletier and Lebel, 1979). On a yearly basis, between 15 and 20 % of the outflow of dissolved inorganic carbon from the St. Lawrence River into its estuary originates from the system's tributaries (e.g., Ottawa River, Mascouche River) while 80-85 % is from the Great Lakes (Hélie et al, 2002). The SLE begins at the landward limit of the saltwater intrusion near Île d'Orléans (∼ 5 km downstream of Québec City) and stretches 400 km seaward to Pointe-des-Monts where it widens into the Gulf of St. Lawrence (GSL) (El-Sabh and ), a semi-enclosed sea with an area of approximately 240 000 km 2 (Dufour and Ouellet, 2007) connected to the Atlantic Ocean through Cabot Strait and the Strait of Belle Isle (Coote and Yeats, 1979).…”

Section: Study Area -St Lawrence Estuary and Gulfmentioning

confidence: 99%

Spatial variability in surface-water <i>p</i>CO<sub>2</sub> and gas exchange in the world's largest semi-enclosed estuarine system: St. Lawrence Estuary (Canada)

Dinauer

Mucci

2017

Biogeosciences

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Abstract. The incomplete spatial coverage of CO 2 partial pressure (pCO 2 ) measurements across estuary types represents a significant knowledge gap in current regional-and global-scale estimates of estuarine CO 2 emissions. Given the limited research on CO 2 dynamics in large estuaries and bay systems, as well as the sources of error in the calculation of pCO 2 (carbonic acid dissociation constants, organic alkalinity), estimates of air-sea CO 2 fluxes in estuaries are subject to large uncertainties. The Estuary and Gulf of St. Lawrence (EGSL) at the lower limit of the subarctic region in eastern Canada is the world's largest estuarine system, and is characterized by an exceptional richness in environmental diversity. It is among the world's most intensively studied estuaries, yet there are no published data on its surface-water pCO 2 distribution. To fill this data gap, a comprehensive dataset was compiled from direct and indirect measurements of carbonate system parameters in the surface waters of the EGSL during the spring or summer of 2003-2016. The calculated surface-water pCO 2 ranged from 435 to 765 µatm in the shallow partially mixed upper estuary, 139-578 µatm in the deep stratified lower estuary, and 207-478 µatm along the Laurentian Channel in the Gulf of St. Lawrence. Overall, at the time of sampling, the St. Lawrence Estuary served as a very weak source of CO 2 to the atmosphere, with an area-averaged CO 2 degassing flux of 0.98 to 2.02 mmol C m −2 d −1 (0.36 to 0.74 mol C m −2 yr −1 ). A preliminary analysis revealed that respiration (upper estuary), photosynthesis (lower estuary), and temperature (Gulf of St. Lawrence) controlled the spatial variability in surface-water pCO 2 . Whereas we used the dissociation constants of Cai and Wang (1998)

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Seasonal changes in the sources and fluxes of dissolved inorganic carbon through the St. Lawrence River—isotopic and chemical constraint

Cited by 136 publications

References 16 publications

Urban Influences on Stream Chemistry and Biology in the Big Brushy Creek Watershed, South Carolina

Urban Influences on Stream Chemistry and Biology in the Big Brushy Creek Watershed, South Carolina

Hydrological and biological processes modulate carbon, nitrogen and phosphorus flux from the St. Lawrence River to its estuary (Quebec, Canada)

Spatial variability in surface-water <i>p</i>CO<sub>2</sub> and gas exchange in the world's largest semi-enclosed estuarine system: St. Lawrence Estuary (Canada)

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Seasonal changes in the sources and fluxes of dissolved inorganic carbon through the St. Lawrence River—isotopic and chemical constraint

Cited by 136 publications

References 16 publications

Urban Influences on Stream Chemistry and Biology in the Big Brushy Creek Watershed, South Carolina

Urban Influences on Stream Chemistry and Biology in the Big Brushy Creek Watershed, South Carolina

Hydrological and biological processes modulate carbon, nitrogen and phosphorus flux from the St. Lawrence River to its estuary (Quebec, Canada)

Spatial variability in surface-water &lt;i&gt;p&lt;/i&gt;CO&lt;sub&gt;2&lt;/sub&gt; and gas exchange in the world's largest semi-enclosed estuarine system: St. Lawrence Estuary (Canada)

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Spatial variability in surface-water <i>p</i>CO<sub>2</sub> and gas exchange in the world's largest semi-enclosed estuarine system: St. Lawrence Estuary (Canada)