Renewal and Entrainment in Loch Eil; A Periodically Ventilated Scottish Fjord

Edwards, A.; Edelsten, D. J.; Saunders, MA; Stanley, S. O.

doi:10.1007/978-1-4613-3105-6_47

Cited by 14 publications

(3 citation statements)

References 4 publications

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“…Unlike Loch Etive the bottom water is well connected to the Firth of Lorn, and on an annual basis there is no stagnation and the water column is well oxygenated (Pearson, 1981 ;Edwards et al, 1980). Loch Eil receives waste from a paper mill where it joins Loch Linnhe.…”

Section: Study Sitesmentioning

confidence: 97%

Determination of the Substrates for Sulphate-reducing Bacteria within Marine and Esturaine Sediments with Different Rates of Sulphate Reduction

et al. 1989

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The substrates used by sulphate-reducing bacteria in sediment slurries from Loch Eil, Loch Etive and the Tay estuary were determined by selectively inhibiting sulphate reduction with 20 mM-molybdate and measuring the resultant substrate accumulation. Substrate accumulation was linear after molybdate addition, and the rate of accumulation closely matched sulphate reduction rates, indicating that metabolic pathways other than those specifically involving sulphate reduction were not affected by the inhibitor. In sediments from all three sites acetate was a major substrate, although the percentage of sulphate reduced due to acetate oxidation varied considerably among the sites (Tay estuary, 35%; Loch Eil, 64%; Loch Etive, 100%). In addition to acetate, 17 individual substrates were shown to be involved in sulphate reduction to varying extents in the Tay estuary and Loch Eil sediments; these included lactate, H2, propionate, iso-and n-butyrate, iso-and n-valerate, 2-methylbutyrate and amino acids. At both sites propionate accounted for between 6 and 12% of sulphate reduction. Butyrate (n-and iso-), iso-valerate and 2-methylbutyrate were of approximately equal importance at each site and together accounted for 13 and 11 %, respectively, of the sulphate reduction in the Tay estuary and Loch Eil sediments. Lactate was only important in the Tay estuary sediments, where it accounted for 43 % of sulphate reduction. The rate of accumulation of amino acids was greatest in the Tay estuary sediments, but the contribution of amino acids to sulphate reduction was higher in the Loch Eil(9 %) than in the Tay estuary sediments (2 %). Of the 21 individual amino acids that were measured there was a linear increase in nine; the most important of these were serine, glutamate and arginine. In general, when sulphate reduction rates were high the substrates for this process were more varied than when rates were low. Combining the results of two experiments and assuming complete degradation of the individual substrates, almost all the sulphate reduction could be accounted for at each site (Tay estuary, 101 %; Loch Eil, 98%; Loch Etive, > 100%).

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Section: Study Sitesmentioning

confidence: 97%

Determination of the Substrates for Sulphate-reducing Bacteria within Marine and Esturaine Sediments with Different Rates of Sulphate Reduction

et al. 1989

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“…[Price and $kei, 1975;$kei and Melsom, 1982]. Further evidence was found by Edwards et al [1980] in a Scottish fjord, Loch Eil, where bottom waters are ventilated during every period of spring tides. Nearbottom sediment traps in Loch Eil showed a greatly increased trapping rate during the spring tides, the result of either increased erosional activity at the trap sites and/or advection of turbid bottom water past the trap sites.…”

Section: Introductionmentioning

confidence: 99%

Patterns of suspended particle distribution and transport in a large fjordlike estuary

Baker¹

1984

J. Geophys. Res.

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Seasonal and spatial patterns of the distribution and transport of suspended particles in Puget Sound, a large fjordlike estuary, are a product of the interaction of the subtidal circulation with surface and bottom particle sources. The particle distribution differs from the distribution of hydrographic properties and is characterized by four persistant features: (1) a thin (<10 m), high‐turbidity surface layer, (2) a thick (∼50 m), low‐turbidity zone centered around the level of no net motion between net seaward and landward flow, (3) horizontal particle fronts at the sill entrances, and (4) a bottom nepheloid layer maintained by local resuspension. Removal of particles from the surface waters by advective downwelling at the seaward sill and gravitational settling throughout the basin make Puget Sound an efficient particle trap. Particles sedimented on the basin floor are transported preferentially landward by the action of erosion/deposition cycles enhanced by fortnightly intrusions of new marine water.

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“…Fortnightly (spring‐neap) variations in vertical mixing generated by tidal currents over the sill can affect bottom‐water renewal processes in the adjoining basins [e.g., Edwards et al ., ]. The mechanical energy dissipated during mixing leads to a form of “hydraulic control,” whose restriction on deep water ventilation can be quantified in terms of the cube‐root‐mean‐cubed (CRMC) tidal velocity [ Griffin and LeBlond , ; see Appendix ].…”

Section: Discussionmentioning

confidence: 99%

Buoyancy‐driven coastal current blocks ventilation of an anoxic fjord on the Pacific coast of Canada

Thomson

Spear

Krassovski³

et al. 2017

JGR Oceans

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Shallow sills restrict the ventilation of deep coastal fjords. Dense oceanic water seaward of the sill and lower density water within the receiving basin are generally required for oxygenated water to cross the sill and descend deep into the fjord. Here we use concurrent 10 year time series from current meters in the fjord and on the continental shelf to examine ventilation of the 120 m deep, anoxic inner basin of Effingham Inlet on the west coast of Vancouver Island. Whereas density currents traverse the 40 m deep sill and flow into the inner basin at mid‐depth at quasi‐fortnightly tidal intervals, only five current intrusions descended to the bottom of the basin over the decade‐long measurement period. The deep intrusions had a mean (±SD) return interval of 1.75 (±1.33) years and induced bottom‐water changes that persisted for 1–2 months. We show that, in addition to conditions within the inlet, deep ventilation of the inner basin is dependent on a coordinated sequence of external processes: (1) the onset of upwelling winds along the outer coast; (2) reversal of the buoyancy‐driven coastal current that normally flows poleward over the inner shelf off Vancouver Island; and (3) reversal of the estuarine circulation in the channel connecting the inlet to the ocean. As the observed ventilation intervals are short compared to the decadal intervals derived from the spacing of “homogenites” (sedimentation sequences disrupted by intruding bottom currents), the use of homogenites as proxies for past upwelling conditions in the northeast Pacific may need to be reexamined.

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Renewal and Entrainment in Loch Eil; A Periodically Ventilated Scottish Fjord

Cited by 14 publications

References 4 publications

Determination of the Substrates for Sulphate-reducing Bacteria within Marine and Esturaine Sediments with Different Rates of Sulphate Reduction

Determination of the Substrates for Sulphate-reducing Bacteria within Marine and Esturaine Sediments with Different Rates of Sulphate Reduction

Patterns of suspended particle distribution and transport in a large fjordlike estuary

Buoyancy‐driven coastal current blocks ventilation of an anoxic fjord on the Pacific coast of Canada

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