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Characterizing baseline concentrations, proportions, and processes controlling deposition of river-transported bitumen-associated polycyclic aromatic compounds at a floodplain lake (Slave River Delta, Northwest Territories, Canada).

Elmes MC, Wiklund JA, Van Opstal SR, Wolfe BB, Hall RI - Environ Monit Assess (2016)

Bottom Line: Here, we use paleolimnological data from a flood-prone lake ("SD2", informal name) in the Slave River Delta (SRD, Canada), ∼ 500 km downstream of the Alberta oil sands development and the bitumen-rich McMurray Formation to identify baseline concentrations and proportions of "river-transported bitumen-associated indicator polycyclic aromatic compounds" (indicator PACs; Hall et al. 2012) and processes responsible for their deposition.Results show that indicator PACs are deposited in SD2 by Slave River floodwaters in concentrations that are 45 % lower than those in sediments of "PAD31compounds", a lake upstream in the Athabasca Delta that receives Athabasca River floodwaters.Although we cannot assess potential changes in indicator PACs during the past decade, baseline concentrations and proportions can be used to enhance ongoing monitoring efforts.

View Article: PubMed Central - PubMed

Affiliation: Department of Geography and Environmental Studies, Wilfrid Laurier University, 75 University Ave West, Waterloo, ON, N2L 3C5, Canada. elmes.matt@gmail.com.

ABSTRACT
Inadequate knowledge of baseline conditions challenges ability for monitoring programs to detect pollution in rivers, especially where there are natural sources of contaminants. Here, we use paleolimnological data from a flood-prone lake ("SD2", informal name) in the Slave River Delta (SRD, Canada), ∼ 500 km downstream of the Alberta oil sands development and the bitumen-rich McMurray Formation to identify baseline concentrations and proportions of "river-transported bitumen-associated indicator polycyclic aromatic compounds" (indicator PACs; Hall et al. 2012) and processes responsible for their deposition. Results show that indicator PACs are deposited in SD2 by Slave River floodwaters in concentrations that are 45 % lower than those in sediments of "PAD31compounds", a lake upstream in the Athabasca Delta that receives Athabasca River floodwaters. Lower concentrations at SD2 are likely a consequence of sediment retention upstream as well as dilution by sediment influx from the Peace River. In addition, relations with organic matter content reveal that flood events dilute concentrations of indicator PACs in SD2 because the lake receives high-energy floods and the lake sediments are predominantly inorganic. This contrasts with PAD31 where floodwaters increase indicator PAC concentrations in the lake sediments, and concentrations are diluted during low flood influence intervals due to increased deposition of lacustrine organic matter. Results also show no significant differences in concentrations and proportions of indicator PACs between pre- (1967) and post- (1980s and 1990 s) oil sands development high flood influence intervals (t = 1.188, P = 0.279, d.f. = 6.136), signifying that they are delivered to the SRD by natural processes. Although we cannot assess potential changes in indicator PACs during the past decade, baseline concentrations and proportions can be used to enhance ongoing monitoring efforts.

No MeSH data available.


Related in: MedlinePlus

Average proportions of 46 detected PACs for the resubmitted samples representing periods of high flood influence pre- versus post-oil sands development for a SD2 and b PAD31. Error bars represent the standard error of individual PACs about the sample average. Gray bars indicate the seven river-transported bitumen-associated indicator PACs identified by Hall et al. (2012)
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Fig5: Average proportions of 46 detected PACs for the resubmitted samples representing periods of high flood influence pre- versus post-oil sands development for a SD2 and b PAD31. Error bars represent the standard error of individual PACs about the sample average. Gray bars indicate the seven river-transported bitumen-associated indicator PACs identified by Hall et al. (2012)

Mentions: At SD2, PACs were dominated by alkylated naphthalenes, phenanthrenes/anthracenes, and perylene in both pre- and post-oil sands samples (Fig. 5a). An ANOSIM test identified a significant difference in the proportions of the 46 detected PACs between pre- and post-oil sands samples (R statistic = 0.265, P = 0.013). However, a SIMPER analysis detected only 6.4 % dissimilarity in PAC proportions between pre- and post-oil sands samples. PACs accounting for most of the dissimilarity were not those identified as river-transported bitumen-associated indicator PACs by Hall et al. (2012) (Table 2). River-transported bitumen-associated indicator PACs contributed only 0.68 % of the total of 6.4 % of total dissimilarity or ∼10 % of total dissimilarity between pre- and post-oil sands samples. Overall, PAC composition is similar between pre- and post-oil sands samples (93.6 % similarity) and differences in relative proportions of individual PACs are subtle (Table 2). This includes river-transported bitumen-associated PACs, for which the average proportion was 0.106 ± 0.004 in pre-oil sands samples and 0.112 ± 0.008 in post-oil sands samples (Table 1). Independent-samples t test indicated no significant difference in mean proportions of river-transported bitumen-associated indicator PACs between pre- and post-oil sands samples (t = 1.627, P = 0.146, d.f. = 7.221).Fig. 5


Characterizing baseline concentrations, proportions, and processes controlling deposition of river-transported bitumen-associated polycyclic aromatic compounds at a floodplain lake (Slave River Delta, Northwest Territories, Canada).

Elmes MC, Wiklund JA, Van Opstal SR, Wolfe BB, Hall RI - Environ Monit Assess (2016)

Average proportions of 46 detected PACs for the resubmitted samples representing periods of high flood influence pre- versus post-oil sands development for a SD2 and b PAD31. Error bars represent the standard error of individual PACs about the sample average. Gray bars indicate the seven river-transported bitumen-associated indicator PACs identified by Hall et al. (2012)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4829623&req=5

Fig5: Average proportions of 46 detected PACs for the resubmitted samples representing periods of high flood influence pre- versus post-oil sands development for a SD2 and b PAD31. Error bars represent the standard error of individual PACs about the sample average. Gray bars indicate the seven river-transported bitumen-associated indicator PACs identified by Hall et al. (2012)
Mentions: At SD2, PACs were dominated by alkylated naphthalenes, phenanthrenes/anthracenes, and perylene in both pre- and post-oil sands samples (Fig. 5a). An ANOSIM test identified a significant difference in the proportions of the 46 detected PACs between pre- and post-oil sands samples (R statistic = 0.265, P = 0.013). However, a SIMPER analysis detected only 6.4 % dissimilarity in PAC proportions between pre- and post-oil sands samples. PACs accounting for most of the dissimilarity were not those identified as river-transported bitumen-associated indicator PACs by Hall et al. (2012) (Table 2). River-transported bitumen-associated indicator PACs contributed only 0.68 % of the total of 6.4 % of total dissimilarity or ∼10 % of total dissimilarity between pre- and post-oil sands samples. Overall, PAC composition is similar between pre- and post-oil sands samples (93.6 % similarity) and differences in relative proportions of individual PACs are subtle (Table 2). This includes river-transported bitumen-associated PACs, for which the average proportion was 0.106 ± 0.004 in pre-oil sands samples and 0.112 ± 0.008 in post-oil sands samples (Table 1). Independent-samples t test indicated no significant difference in mean proportions of river-transported bitumen-associated indicator PACs between pre- and post-oil sands samples (t = 1.627, P = 0.146, d.f. = 7.221).Fig. 5

Bottom Line: Here, we use paleolimnological data from a flood-prone lake ("SD2", informal name) in the Slave River Delta (SRD, Canada), ∼ 500 km downstream of the Alberta oil sands development and the bitumen-rich McMurray Formation to identify baseline concentrations and proportions of "river-transported bitumen-associated indicator polycyclic aromatic compounds" (indicator PACs; Hall et al. 2012) and processes responsible for their deposition.Results show that indicator PACs are deposited in SD2 by Slave River floodwaters in concentrations that are 45 % lower than those in sediments of "PAD31compounds", a lake upstream in the Athabasca Delta that receives Athabasca River floodwaters.Although we cannot assess potential changes in indicator PACs during the past decade, baseline concentrations and proportions can be used to enhance ongoing monitoring efforts.

View Article: PubMed Central - PubMed

Affiliation: Department of Geography and Environmental Studies, Wilfrid Laurier University, 75 University Ave West, Waterloo, ON, N2L 3C5, Canada. elmes.matt@gmail.com.

ABSTRACT
Inadequate knowledge of baseline conditions challenges ability for monitoring programs to detect pollution in rivers, especially where there are natural sources of contaminants. Here, we use paleolimnological data from a flood-prone lake ("SD2", informal name) in the Slave River Delta (SRD, Canada), ∼ 500 km downstream of the Alberta oil sands development and the bitumen-rich McMurray Formation to identify baseline concentrations and proportions of "river-transported bitumen-associated indicator polycyclic aromatic compounds" (indicator PACs; Hall et al. 2012) and processes responsible for their deposition. Results show that indicator PACs are deposited in SD2 by Slave River floodwaters in concentrations that are 45 % lower than those in sediments of "PAD31compounds", a lake upstream in the Athabasca Delta that receives Athabasca River floodwaters. Lower concentrations at SD2 are likely a consequence of sediment retention upstream as well as dilution by sediment influx from the Peace River. In addition, relations with organic matter content reveal that flood events dilute concentrations of indicator PACs in SD2 because the lake receives high-energy floods and the lake sediments are predominantly inorganic. This contrasts with PAD31 where floodwaters increase indicator PAC concentrations in the lake sediments, and concentrations are diluted during low flood influence intervals due to increased deposition of lacustrine organic matter. Results also show no significant differences in concentrations and proportions of indicator PACs between pre- (1967) and post- (1980s and 1990 s) oil sands development high flood influence intervals (t = 1.188, P = 0.279, d.f. = 6.136), signifying that they are delivered to the SRD by natural processes. Although we cannot assess potential changes in indicator PACs during the past decade, baseline concentrations and proportions can be used to enhance ongoing monitoring efforts.

No MeSH data available.


Related in: MedlinePlus