Hydrocarbon transport in the Mackenzie River, Canada

Carey, John H.; Ongley, Edwin D.; Nagy, E.

doi:10.1016/0048-9697(90)90231-i

Cited by 22 publications

(6 citation statements)

References 39 publications

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“…18,500-15,000 yr BP, Zazula et al, 2009;Lacelle et al, 2013), thus it is characterized by relatively OCpoor deposits, and hosts glacial tills bearing petrogenic OC from underlying shale bedrock, whereas Yedoma regions remained ice-free and incorporated organic matter from vegetation during aggradation (Yunker et al, 2002;Lacelle et al, 2013;Ewing et al, 2015;Strauss et al, 2017). Petrogenic materials, such as shales, are known to be present in the lower Mackenzie River (Carey et al, 1990;Yunker et al, 2002), and account for 10-30% of the suspended OC load in the Mackenzie Delta (Hilton et al, 2015).…”

Section: Bulk Characteristics Of the Transect Source Materialsmentioning

confidence: 99%

Downstream Evolution of Particulate Organic Matter Composition From Permafrost Thaw Slumps

et al. 2021

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Permafrost soils, which store almost half of the global belowground organic carbon (OC), are susceptible to thaw upon climate warming. On the Peel Plateau of northwestern Canada, the number and size of retrogressive thaw slumps (RTS) has increased in recent decades due to rising temperatures and higher precipitation. These RTS features caused by the rapid thaw of ice-rich permafrost release organic matter dominantly as particulate organic carbon (POC) to the stream network. In this study, we sampled POC and streambank sediments along a fluvial transect (∼12 km) downstream from two RTS features and assessed the composition and degradation status of the mobilized permafrost OC. We found that RTS features add old, Pleistocene-aged permafrost POC to the stream system that is traceable kilometers downstream. The POC released consists mainly of recalcitrant compounds that persists within stream networks, whereas labile compounds originate from the active layer and appear to largely degrade within the scar zone of the RTS feature. Thermokarst on the Peel Plateau is likely to intensify in the future, but our data suggest that most of the permafrost OC released is not readily degradable within the stream system and thus may have little potential for atmospheric evasion. Possibilities for the recalcitrant OC to degrade over decadal to millennial time scales while being transported via larger river networks, and within the marine environment, do however, still exist. These findings add to our understanding of the vulnerable Arctic landscapes and how they may interact with the global climate.

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Section: Bulk Characteristics Of the Transect Source Materialsmentioning

confidence: 99%

Downstream Evolution of Particulate Organic Matter Composition From Permafrost Thaw Slumps

et al. 2021

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“…[2] The Delta forms part of the Mackenzie River Basin which covers approximately 1.8 million km 2 of western and northern Canada. [3] In 1990, Carey et al [4] reported that at low flow conditions in the Mackenzie River system PAHs originated from petroleum-related sources, whereas under high flow conditions the PAH patterns were dominated by atmospherically dominated combustion-related PAHs that had been carried into the river by snowmelt. [3] While the northern portion of the Mackenzie basin is largely undeveloped, there is significant industrial development in the southern portions of the basin, including oil and gas developments, oilsands operations, forestry and agriculture.…”

Section: Introductionmentioning

confidence: 99%

Origin of Polycyclic Aromatic Hydrocarbons in Lake Sediments of the Mackenzie Delta

Headley¹,

Marsh²,

Akre³

et al. 2002

Journal of Environmental Science and Health, Part A

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The concentrations and distribution of polycyclic aromatic hydrocarbons (PAHs) were assessed in sediment cores from among 14 lakes from three regions comprising a transect across the central Mackenzie Delta. PAHs were consistently found in the lake sediments, with parent concentrations in the 20-200 ng/g range. Concentrations were generally independent of depth in the sediment cores and this pattern was similar among the 3 regions of the delta. Concentrations increased in a westerly direction among the regions. For some lakes, the concentration of PAHs decreased with decreasing flooding frequency, and decreasing sedimentation rates. For the latter, maximum concentrations occurred at shallower depths within the sediment cores as flooding frequency among the lakes decreased. The distributions of C0-C4 alkylated 2- and 3- ring PAHs were consistent with a petrogenic origin, while the corresponding distribution of 4-ring PAHs appears to be more consistent with a biogenic or pyrogenic origin. Based on relative contributions to the overall PAH budget, a petrogenic source appears to be dominant. However, the pyrene/fluoranthene ratio is more consistent with a source derived from peat. The alkylated PAH profiles are inconsistent with those in the Athabasca River system, and supports a previously published hypothesis that the contribution of PAHs from the Athabasca oil sands to the lower Mackenzie River is minimal. A double ratio plot of chrysene vs dibenzothiophene, diagnostic of weathering, suggests most weathering occurred before the sediments were deposited in the lakes, while a double ratio plot of dibenzothiophene vs phenanthrene suggests a common source of PAHs across the delta, despite differing water sources from east to west across the delta. PAH inputs to the delta appear to mirror sediment inputs documented in previous work, where high sediment input from the Mackenzie mainstem during high floods dominates the delta sediment influx and masks any influence of the Peel River.

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“…Urnlauf & Bierl conclude that PAH transport must take into account the transport characteristics of the silt fraction . Carey et al (1990) found in the Mackenzie River that individual PAHs displayed differing affinities for sediment and aqueous phases .…”

Section: Introductionmentioning

confidence: 99%

Cohesive sediment transport: emerging issues for toxic chemical management

et al. 1992

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The association of many environmentally sensitive chemicals and their transformation products with mineral and organic substrates is of considerable importance for environmental monitoring, prediction and management purposes in rivers and their basins . Our understanding of these relationships is poor . This paper reviews processes of particular concern, including the physical behaviour of fine-grained (< 63 µm) sediment in freshwater ; the role of flocculation as a transport vector ; the processes that control freshwater flocculation including microbiological factors ; the uncertainty in conventional sediment transport models for predicting pathways of sediment-associated chemistry ; the relationship between suspended sediment and toxicity in the water column ; and the partitioning of chemicals between the sediment, organic and water phase, including the significance of these in predicting chemical transport on suspended matter . 177

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Hydrocarbon transport in the Mackenzie River, Canada

Cited by 22 publications

References 39 publications

Downstream Evolution of Particulate Organic Matter Composition From Permafrost Thaw Slumps

Downstream Evolution of Particulate Organic Matter Composition From Permafrost Thaw Slumps

Origin of Polycyclic Aromatic Hydrocarbons in Lake Sediments of the Mackenzie Delta

Cohesive sediment transport: emerging issues for toxic chemical management

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