Magnitude and Sources of Sediment Input to the Mackenzie Delta, Northwest Territories, 1974-94

Carson, M. A.; Jasper, Jesse N.; Conly, F. Malcolm

doi:10.14430/arctic1053

Cited by 104 publications

(101 citation statements)

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“…The Mackenzie River (Figure 1) contributes the fourth largest amount of freshwater to the Arctic Ocean (330 km 3 /year) and is by far the largest source of fluvial sediments (124 Mt/year; Carson et al, 1998). Organic carbon fluxes from this river are also high, with TOC and POC fluxes of 4.1 Tg C and 2.6 Tg C/year, respectively (McGuire et al, 2009;Hilton et al, 2015).…”

Section: Study Sitementioning

confidence: 99%

“…As with most northern rivers, the Mackenzie is characterized by a strong seasonal hydrograph (Figure 2) where ∼20% of the annual discharge is delivered during a 30 day period in the spring-the freshet (Emmerton et al, 2008b). Sediment transport is even more strongly seasonal, with the river delivering roughly 63% of its annual sediment load to the delta during the months of May and June (Carson et al, 1998).…”

Section: Study Sitementioning

confidence: 99%

“…Nearly all of the water in the delta (83-90%) is delivered by the Mackenzie River at Point Separation (Figure 1) with minor contributions from the Peel River (∼8%) and other tributaries to the delta (Carson et al, 1998;Emmerton et al, 2007). The Peel River, however, delivers FIGURE 1 | Map of the Mackenzie River delta with the major tributaries, distributary channels and geographic features labeled.…”

Section: Study Sitementioning

confidence: 99%

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Arctic Deltaic Lake Sediments As Recorders of Fluvial Organic Matter Deposition

et al. 2016

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Arctic deltas are dynamic and vulnerable regions that play a key role in land-ocean interactions and the global carbon cycle. Delta lakes may provide valuable historical records of the quality and quantity of fluvial fluxes, parameters that are challenging to investigate in these remote regions. Here we study lakes from across the Mackenzie Delta, Arctic Canada, that receive fluvial sediments from the Mackenzie River when spring flood water levels rise above natural levees. We compare downcore lake sediments with suspended sediments collected during the spring flood, using bulk (% organic carbon, % total nitrogen, 13 δ C, 14 C) and molecular organic geochemistry (lignin, leaf waxes). High-resolution age models ( 137 Cs, 210 Pb) of downcore lake sediment records (n = 11) along with lamina counting on high-resolution radiographs show sediment deposition frequencies ranging between annually to every 15 years. Down-core geochemical variability in a representative delta lake sediment core is consistent with historical variability in spring flood hydrology (variability in peak discharge, ice jamming, peak water levels). Comparison with earlier published Mackenzie River depth profiles shows that (i) lake sediments reflect the riverine surface suspended load, and (ii) hydrodynamic sorting patterns related to spring flood characteristics are reflected in the lake sediments. Bulk and molecular geochemistry of suspended particulate matter from the spring flood peak and lake sediments are relatively similar showing a mixture of modern higher-plant derived material, older terrestrial permafrost material, and old rock-derived material. This suggests that deltaic lake sedimentary records hold great promise as recorders of past (century-scale) riverine fluxes and may prove instrumental in shedding light on past behavior of arctic rivers, as well as how they respond to a changing climate.

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Section: Study Sitementioning

confidence: 99%

Section: Study Sitementioning

confidence: 99%

Section: Study Sitementioning

confidence: 99%

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Arctic Deltaic Lake Sediments As Recorders of Fluvial Organic Matter Deposition

et al. 2016

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“…The eastern Beaufort Shelf (also known as the Mackenzie Shelf) is an attractive system for such a study because of the large annual sediment load of the Mackenzie River (ϳ128 million tons of mostly silt and clay, which is twice the combined loads of the larger Arctic rivers, Ob, Yenisey, and Lena; Carson et al 1998) and is thought to account for ϳ95% of the shelf sediment supply (Macdonald et al 1998). At least during open-water season, benthic nepheloid layers and a particle-rich surface plume have regularly been observed in the vicinity of the river mouth (e.g., Iseki et al 1987;Carmack et al 1989); farther offshore, bottom currents and storms can mobilize sediments into additional nepheloid layers (Hill et al 1991).…”

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confidence: 99%

Archaea in particle-rich waters of the Beaufort Shelf and Franklin Bay, Canadian Arctic: Clues to an allochthonous origin?

et al. 2006

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We used 4Ј,6-diamidino-2-phenylindole (DAPI) staining and fluorescent in situ hybridization to examine total bacterioplankton and archaeal distributions in surface waters and in deeper nepheloid layers and particle-poor waters across the Beaufort Shelf of the Canadian Arctic, including the Mackenzie River and Kugmallit Bay, as well as more distant Franklin Bay. Although the regional distribution of bacterioplankton was best explained by salinity (r s ϭ Ϫ0.89, n ϭ 28, p Ͻ 0.001) and indicators of primary production (chlorophyll a [Chl a], total organic carbon, and the ratio of Chl a to particulate organic carbon [Chl a : POC]), that of Archaea instead reflected measures of particulate matter, specifically microscopically determined particle concentration (r s ϭ 0.85, n ϭ 30, p Ͻ 0.001), suspended particulate matter, POC, particulate organic nitrogen (PON), and the beam attenuation coefficient. Moreover, when compared with similarly deep particle-poor waters, nepheloid layers were significantly enriched in Archaea (median concentration of 6.00 ϫ 10 4 mL Ϫ1 [15.5% of bacterioplankton] vs. 1.79 ϫ 10 4 mL Ϫ1 [3.6%]; p Ͻ 0.05), but not total bacterioplankton. The relationship between Archaea and particles, the dominance of the Mackenzie River as the regional particle source, the detection of highest archaeal concentrations (11.5-14.4 ϫ 10 4 mL Ϫ1) in the river, and the highly significant correlation (r s ϭ 0.97, n ϭ 12, p Ͻ 0.001) between Archaea in particle-rich waters and PON (the river providing the upper end member) suggest that many of these Archaea derive from the river.Archaea have now been recognized as ubiquitous and sometimes abundant members of the marine bacterioplank-1 Corresponding author (chimera1@ocean.washington.edu). 2 Present address: Department of Bioengineering, Rice University, Houston, Texas 77005.3 Present address: Department of Biology, University of Washington, Seattle, Washington 98195. AcknowledgmentsWe thank the officers and crew of the NGCC Pierre Radisson, Louis Fortier for leadership of the Canadian Arctic Shelf Exchange Study (CASES), and Martin Fortier for his work as chief scientist. We also thank J.-E. Tremblay (Laval University, Quebec) for generously providing us with nutrient data, S. Demers and K. Lacoste (University of Quebec at Rimouski) for the POC, PON, and Chl a data, and Y. Gratton (INRS-Eau, Terre et Environnement, University of Quebec) for the CTD and transmissivity profiles. We appreciated the hard work of the water column sampling team of G. Desmeules, E. Rail, F. Bazinet, and M. Robert and the TOC analyses of Nes Sutherland. T. Papakyriakou (University of Manitoba) kindly discussed wind data with us, and C. Lovejoy (Laval University) commented on an early version of this manuscript. We acknowledge with gratitude the availability of the Ribosomal Database Project II Versions 8.1 and 9.0, as maintained by Michigan State University. Finally, we thank S. Carpenter (University of Washington [UW]) for assistance preparing figures, E. Lessard (UW) for discussion, and...

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“…For this work, we focused on clay particles, which (along with silts) dominate the particle load of the Mackenzie River (Carson et al 1998), the major sediment source for the Mackenzie Shelf area (Macdonald et al 1998), whence 9A was isolated. Two of the clays we chose, kaolinite and illite, are of known regional significance, with illite composing up to 60% of total clays in the area (Mowatt & Naidu 1987).…”

Section: Introductionmentioning

confidence: 99%

Effects of temperature, salinity and clay particles on inactivation and decay of cold-active marine Bacteriophage 9A

Wells¹,

Deming²

2006

Aquat. Microb. Ecol.

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The effects of temperature, salinity and clay particles on the inactivation and decay of the cold-active Bacteriophage 9A, isolated from particle-rich Arctic seawater, were examined using a plating technique to evaluate infectivity (inactivation) and epifluorescence microscopy to measure phage concentrations (decay). Phage 9A was rapidly inactivated over a temperature test range of 25 to 55°C in marine broth (salinity of 36 psu), with half-lives ranging from <10 min at 25°C to ~1 min at 32.5°C and too rapid to measure at ≥35°C, making it among the most thermolabile phages. When salinity was varied at 30°C, the inactivation rates in brackish (21 psu) and briny (161 psu) broth were indistinguishable from that in marine broth (p > 0.20). At the environmentally relevant temperature of -1°C, however, loss of infectivity in briny broth was 3 to 4 times greater than in marine or brackish broth. As commonly observed, viral decay determined microscopically often substantially underestimated loss of infectivity: at 30°C, loss of infectivity exceeded the viral decay rate by approximately 1000-fold, while at -1°C, microscopic counts did not detect any of the losses observed by plaque assay. Under conditions comparable to a winter sea-ice brine inclusion (-12°C and 161 psu), however, plating and microscopy were in substantive agreement, indicating relatively minor losses of 16 to 34% losses over a 5 wk period. Illite, kaolinite or montmorillonite clays had no statistically significant effect on phage inactivation as a function of temperature or salinity, although rates tended to be slower in the presence of the clays. In general, our results emphasize the importance of working with cold-active phages under environmentally-relevant conditions of temperature and salinity. They also imply decay processes that involve viral proteins rather than nucleic acids; as a result, affected viruses may be recalcitrant to reactivation by known host-based repair mechanisms.KEY WORDS: Virus · Phage 9A · Colwellia psychrerythraea 34H · Temperature · Salinity · Clay · Illite · Mackenzie Shelf Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 45: [31][32][33][34][35][36][37][38][39] 2006 show that cold-active viruses are typically more thermolabile than viruses not capable of cold activity. While the latter tend to survive long exposure (60 min or greater) at 60°C with minimal loss of titer (Olsen et al. 1968), a dramatic reduction in titer of ≥99% is common for cold-active viruses at this or cooler temperatures (reported down to 45°C) within 10 min (Spencer 1955, 1963, Olsen et al. 1968, Wiebe & Liston 1968, Kulpa & Olsen 1971, Whitman & Marshall 1971, Delisle & Levin 1972. If associated with greater flexibility in viral proteins, as seen in cold-active enzymes (Feller & Gerday 2003), this increased lability could be an adaptive trait in environments of low thermal energy, for example, facilitating viral interaction with cell-surface receptor(s) or nucleic acid injection.By further ana...

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Magnitude and Sources of Sediment Input to the Mackenzie Delta, Northwest Territories, 1974-94

Cited by 104 publications

References 11 publications

Arctic Deltaic Lake Sediments As Recorders of Fluvial Organic Matter Deposition

Arctic Deltaic Lake Sediments As Recorders of Fluvial Organic Matter Deposition

Archaea in particle-rich waters of the Beaufort Shelf and Franklin Bay, Canadian Arctic: Clues to an allochthonous origin?

Effects of temperature, salinity and clay particles on inactivation and decay of cold-active marine Bacteriophage 9A

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