Sediment redox tracers in Strait of Georgia sediments – Can they inform us of the loadings of organic carbon from municipal wastewater?

Macdonald, Robie W.; Johannessen, Sophia C.; Gobeil, Charles; Wright, Cynthia; Burd, Brenda J.; Roodselaar, Albert van; Pedersen, T. F.

doi:10.1016/j.marenvres.2008.08.001

Cited by 32 publications

(16 citation statements)

References 56 publications

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“…The N concentrations were 0.17-0.26 and 0.20-0.29%, respectively. These values were consistent with published OM data from Dabob Bay, Hood Canal and the Strait of Georgia (Hedges et al 1988a;Walsh et al 2008;Macdonald et al , 2008. In both basins, although there is an increase in OM concentrations towards the surface, there seems to be some variations along the core depth that are not entirely consistent with diagenetic processes.…”

Section: Total Carbon and Nitrogen Concentrationssupporting

confidence: 90%

“…The sediment EF CR increased in the following order: PS-4 \ PS-1 \ HC-5 \ HC-3. This gradient was consistent with the earlier discussion on bottom water DO gradients and not directly attributed to an increase in sediment porosity and decrease in sedimentation rates as noted for the Strait of Georgia (Macdonald et al 2008). The comparison of RSM EF CR for these two time periods, representing natural and post-urbanization signatures, confirms that sediment of Hood Canal and the Main Basin have not become more enriched in RSM during the period of rapid urbanization.…”

Section: Natural and Post-urbanization Rsm Signaturessupporting

confidence: 90%

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Natural and Post-Urbanization Signatures of Hypoxia in Two Basins of Puget Sound: Historical Reconstruction of Redox Sensitive Metals and Organic Matter Inputs

2011

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Hypoxia has been observed in Hood Canal, Puget Sound, WA, USA since the 1970s. Four long sediment cores were collected in 2005 and age-dated to resolve natural and post-urbanization signatures of hypoxia and organic matter (OM) sources in two contrasting basins of Puget Sound: Main Basin and Hood Canal. Paleoecological indicators used for sediment reconstructions included pollen, stable carbon and nitrogen isotopes (d 13 C and d 15 N), biomarkers of terrestrial OM (TOM), biogenic silica (BSi), and redoxsensitive metals (RSM). The sedimentary reconstructions illustrated a gradient in RSM enrichment factors as Hood Canal [ Main Basin, southern [ northern cores, and pre1900s [ 1900-2005. The urbanization of Puget Sound watersheds during the 1900s was reflected as shifts in all the paleoecological signatures. Pollen distributions shifted from predominantly old growth conifer to successional alder, dominant OM signatures recorded a decrease in the proportion of marine OM (MOM) concomitant with an increase in the proportion of TOM, and the weight % of BSi decreased. However, these shifts were not coincidental with an overall increase in the enrichment of RSM or d 15 N signatures indicative of cultural eutrophication. The increased percentage of TOM was independently verified by both the elemental ratios and lignin yields. In addition, isotopic signatures, BSi, and RSMs all suggest that OM shifts may be due to a reduction in primary productivity rather than an increase in OM regeneration in the water column or at the sediment/water interface. Therefore, the reconstructions suggested the Hood Canal has been under a more Electronic supplementary material The online version of this article (oxygenated ''stance'' during the twentieth century compared to prior periods. However, these 2005 cores and their resolutions do not encompass the period of high resolution water column measurements that showed short-lived hypoxia events and fish kills in Hood Canal during the early twenty-first century. The decoupling between the increased watershedscale anthropogenic alterations recorded in the OM signatures and the relatively depleted RSM during the twentieth century suggests that physical processes, such as deep-water ventilation, may be responsible for the historical variation in oxygen levels. Specifically, climate oscillations may influence the ventilation and/or productivity of deep water in Puget Sound and particularly their least mixed regions.

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Section: Total Carbon and Nitrogen Concentrationssupporting

confidence: 90%

Section: Natural and Post-urbanization Rsm Signaturessupporting

confidence: 90%

Natural and Post-Urbanization Signatures of Hypoxia in Two Basins of Puget Sound: Historical Reconstruction of Redox Sensitive Metals and Organic Matter Inputs

2011

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“…Two near the Victoria outfall (CRD-2 and CRD-3), three near the Vancouver outfall (Greater Vancouver Regional District [GVRD]-3, Iona-A, and Iona-B), and two at sites far away from the direct influence of outfalls (GVRD-5 in the Strait of Georgia and CRD-1 in Parry Bay, near the Juan de Fuca Strait). The GVRD-3 and GVRD-5 cores have been described previously [10,15]. The cores collected near the Vancouver outfall were subsampled into 1-cm intervals from the sediment surface to 10 cm; at 2-cm intervals from 10 to 20 cm; and then at 5-cm intervals from 20 cm to the bottom ($50 cm).…”

Section: Sample Collectionmentioning

confidence: 99%

Effect of receiving environment on the transport and fate of polybrominated diphenyl ethers near two submarine municipal outfalls

Dinn¹,

Johannessen²,

Macdonald³

et al. 2012

Enviro Toxic and Chemistry

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The fate of contaminants entering the marine environment through wastewater outfalls depends on the contaminant's persistence and affinity for particles. However, the physical characteristics of the receiving environment, for example, current velocity and sedimentary processes, may be even more important. Because of the complexity of natural settings and the lack of appropriate comparative settings, this is not frequently evaluated quantitatively. The authors investigated the near-field accumulation of particle-reactive polybrominated diphenyl ethers (PBDEs) entering coastal waters by way of two municipal outfalls: one discharging into a high-energy, low-sedimentation environment near Victoria, BC, Canada; the other into a low-energy, high-sedimentation environment, near Vancouver, BC. The authors used ²¹⁰Pb profiles in box cores together with an advection-diffusion model to determine surface mixing and sedimentation rates, and to model the depositional history of PBDEs at these sites. Surprisingly, 88 to 99% of PBDEs were dispersed beyond the near-field at both sites, but a greater proportion of PBDEs was captured in the sediment near the Vancouver outfall where rapid burial was facilitated by inorganic sediment supplied from the nearby Fraser River. Although the discharge of PBDEs was much lower from the Victoria outfall than from Vancouver, some sediment PBDE concentrations were higher near Victoria.

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“…Furthermore, the northern basin appears more isolated from Fraser River inputs [20], and collects settling particles that are subject to a higher degree of weathering and a greater time spent in oxic conditions [24]. Fine sedimentary material has a relatively large surface area, which favors the heavy PBDE congeners.…”

Section: Fractionation Of Pcbs and Pbdes In Coastal Sedimentsmentioning

confidence: 99%

Environmental fractionation of PCBs and PBDEs during particle transport as recorded by sediments in coastal waters

Grant

Johannessen

Macdonald

et al. 2011

Enviro Toxic and Chemistry

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The Strait of Georgia (British Columbia, Canada) is a hydrologically complex inland sea with a rich abundance and diversity of species of aquatic life. Marine sediments, as both a sink for hydrophobic contaminants and a potential source for aquatic food webs, were collected from 41 sites throughout the 6,900-km(2) Strait of Georgia. The congener-specific concentrations of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), including BDE-209, were measured. Urban harbors represented hotspots for both PCBs and PBDEs, whereas PBDEs were also found at high concentrations near municipal outfalls. Patterns of PCB distribution were consistent with historical point source emissions in urban areas and environmental distillation toward lighter profiles in remote sites over time. The single congener BDE-209 dominated the PBDEs, accounting for 52% of the average total concentration. However, nonurban deep-water sediment PBDE profiles were both heavier and had higher concentration-weighted average log K(OW) (octanol-water partition coefficient) values compared to shallow samples (percent BDE-209 of total PBDE, 66 versus 32%; log K(OW) , 9.5 versus 8.2, respectively). Collectively, our results suggest that although source signals largely explain PCB and PBDE hotspots in the Strait of Georgia, the combination of physicochemical properties and environmental processes drive divergent compositional fates for the PCBs and the heavier PBDEs in the sediments of the Strait of Georgia.

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Sediment redox tracers in Strait of Georgia sediments – Can they inform us of the loadings of organic carbon from municipal wastewater?

Cited by 32 publications

References 56 publications

Natural and Post-Urbanization Signatures of Hypoxia in Two Basins of Puget Sound: Historical Reconstruction of Redox Sensitive Metals and Organic Matter Inputs

Natural and Post-Urbanization Signatures of Hypoxia in Two Basins of Puget Sound: Historical Reconstruction of Redox Sensitive Metals and Organic Matter Inputs

Effect of receiving environment on the transport and fate of polybrominated diphenyl ethers near two submarine municipal outfalls

Environmental fractionation of PCBs and PBDEs during particle transport as recorded by sediments in coastal waters

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