Loch Eil Research Articles

The Loch Eil project: Planktonic pigments in sediments from Loch Eil and the firth of Lorne

Photosynthetic pigments and their derivatives were measured in sediments in the fjordic Loch Eil and the Firth of Lome, Scotland, between November 1975 and November 1976. After acetone extraction from the top 10 mm of sediment cores, pigments were crudely separated, by fluorescence change on acidification, into (chlorophyll a + chlorophyllide a) and phaeopigments. The greatest pigment concentrations (mean 73 μg · g sediment dry wt −1) were found in the most reducing sediments which also had a high average proportion (23%) of chlorophyll. The least mean pigment concentration (23 μg · g −1) and proportion of chlorophyll (17%) were found in the most oxidizing sediments in the Firth of Lorne where there was a clear seasonal cycle, with a peak in sediment pigment concentration and chlorophyll proportion in May and June, just after the planktonic spring increase. The Loch Eil stations showed a less clear or no seasonal cycle; the station most affected by organic input was the most variable from month to month. It was concluded that redox status was the most obvious control of sediment pigment content, whereas the effect of sedimentation of phytoplankton was complex.

The Loch Eil project: Sediment chemistry, sedimentation, and the chemistry of the overlying water in Loch Eil

Data are given on the changes in cellulose, carbon, sulphide, and redox levels in the sediments of Loch Eil, Scotland, during 1976. Comparisons are made between sediment rates and average monthly inputs of pulp fibre and the effect of sedimentary material on the sediments described. Studies carried out over 24-h periods during spring and neap tides, suggest that monthly measurements of rates of sedimentation do not provide a true picture of sedimentation and that monthly measurements of sedimentation are more likely to be representative if made during neap tides. Short-term variations in nutrients in the water overlying the sediment are also related to tidal cycles and are influenced by the release of nutrients from the sediment.

The Loch Eil project: Effect of organic matter input on interstitial water chemistry of Loch Eil sediments

Loch Eil is a fjordic marine basin which receives a high input of cellulose fibre in its lower reaches from a pulp and paper mill. This paper reports results of interstitial water profiles examined at two stations; E70 which receives a high input of cellulose fibre and E24, further from the source, and less affected by, the cellulose fibre input. Sulphate reduction commences at the surface of Station E70 and ammonia and alkalinity production are double that at Station E24. Station E70 shows more rapid sulphate depletion which is confirmed by higher solid sulphide concentrations and a more rapid uptake of ferrous iron into the sulphide mineral phase. This station also shows a greater reduction in organic carbon and cellulose and one of the highest proportions of metabolizable organic matter yet reported in the literature. Sedimentation rates of 0.6 and 0.8 cm/yr were calculated for E24 and E70, respectively. The more anoxic Station E70, in response to a high organic matter input, shows a more active microbial population of sulphate reducers and cellulose degraders and a higher rate of organic degradation than Station E24.

The Loch Eil project: The bacterial flora and heterotrophic nitrogen fixation in sediments of Loch Eil

The organically enriched sediments of Loch Eil reduced acetylene (fixed nitrogen) at a higher rate than sediments in the Firth of Lome and other near shore marine locations. Sulphate-reducing bacteria (SRB) were implicated in nitrogen fixation although fixation rates did not correlate with the SRB numbers found in these sediments. The data suggest that a negative relationship may exist between nitrogen fixation and the sulphide content of sediments.

The loch eil project: introduction and rationale

The Loch Eil project, a multidisciplinary study of the distribution and fate of carbon inputs to Loch Eil, a sea loch on the west coast of Scotland receiving pulp and paper mill effluent, is described. Publications stemming from the project consist of eleven individual contributions and an attempted synthesis. A framework and justification of the project are provided, a description of effluent input to the system and the physical characteristics of the area studied are given, and the range of work undertaken is described in the context of the known processes and pathways involved in the degradation of organic material entering the loch system.

The Loch eil project: Simulation of the hydrology and sediment inputs to Loch Eil

The two objectives of the study were the assessment of the water and sediment response of the ungauged catchments draining to Loch Eil, and the analysis of the sensitivity of erosion processes to the variation of input precipitation and sediment characteristics. The technique employed was the application of the Strathclyde Sediment Model I, which had already been tested on the Scottish river basins using data from several sources. The method showed some potential but provided only a rough comparison with the actual sedimentation in the Loch.

A biochemical approach to assessment of effects of organic pollution on the metabolism of the non-opportunistic polychaete,Glycera alba

Loch Creran and Loch Eil, sea lochs in the west of Scotland, both receive discharges of particulate organic effluent from industrial installations.Glycera alba (Muller) is widely distributed in the sediments of both lochs, and assays of activities of enzymes associated with energy-yielding metabolism have been done on crude extracts of specimens collected from variously affected areas. Mean phosphofructokinase activities were low in extracts ofG. alba collected some 400 m from the source of effluent from a seaweed processing factory, increased to a maximum at 900 m and declined slightly at 1150 m where the sediment is little affected by the effluent. Pyruvate kinase activities exhibited qualitatively similar changes of lesser magnitude and no differences ina-glycerophosphate or malate dehydrogenase activities were observed. InG. alba from Loch Eil a relationship was established between phosphofructokinase activity and Eh at 4 cm in the sediment and the maximum change in phosphofructokinase was found at low Eh, below −50 mV. The data are interpreted with reference to results from biological and environmental monitoring in Lochs Eil and Creran. It is suggested that the low phosphofructokinase activities inG. alba from the most affected areas of each loch may constitute a consistent biochemical response to effects of the organic inputs.

Some biologically important low molecular weight organic acids in the sediments of Loch Eil

The isolation of biologically important low molecular weight organic acids from organically enriched sediments in Loch Eil, Scotland, was carried out by extraction of pore water with acidified ethyl acetate. High concentrations of acetic acid, up to 1.8 mg g-1 dry weight of sediment were found at Station E-24. Propionate, butyrate, valerate, lactate and traces of succinate were also found. Succinate was present in significant amounts, 42.2 μg g-1 dry weight of sediment at Station E-70, which received a higher input of organic matter than E-24. Both propionate and succinate were absent from a control station in the Lynn of Lorne where the sediment was low in carbon compared with Loch Eil. In experimental tanks, acetate levels increased as the input of organic carbon (as cellulose) was increased up to a load level of 1.5 g m-2 day-1. Above this, acetate decreased and succinate appeared. Succinate was not detected in low-loaded tanks. Experiments with sieved mud showed a vertical distribution of the different acids with depth. Lactate and succinate reached highest concentration in the 0 to 3 cm layer, acetate at 3 to 6 cm and propionate at 6 to 9 cm. The results are discussed in relation to the role of these acids as food sources and as indicators of biochemical pathways taking place in sediments with different carbon input levels.

Time, space and intensity relationships of the Precambrian and lower Palaeozoic metamorphisms of the Scottish Highlands

Summary Isotopic evidence suggests that a complex sequence of events, collectively known to us as the Morarian event, affected the Morar and Glenfinnan divisions of the Moine from 1000 to 750 Ma. A regional thermal anticline, with a minimum age of 750 Ma, extends north from Ardgour to northern Ross-shire: it probably extends southwards under the eastern Dalradian. This thermal anticline is cut across and shifted westwards south of Monar by the Sgurr Beag slide, on which up to 25 km thrust movement is estimated. The Loch Eil Division lacks old isotopic ages; it appears to be structurally and metamorphically simpler than the Morar and Glenfinnan divisions and it also differs from them geochemically. The simplest explanation of these facts is that Loch Eil Division rests unconformably on the metamorphosed Glenfinnan Division. The Central Highland Group (including the Monadhliath Schists) is presumed to occupy the same tectono-stratigraphical niche as the Loch Eil Division. Grampian events (510-480 Ma) produced three thermal highs of sillimanite grade: one in the Monadhliaths, the second in the NE Grampians, and the third affecting E Sutherland. Throughout most of the area under consideration, Grampian age isograd surfaces appear to dip at low angles.

The ‘Central Highland Granulites’: cover-basement tectonics in the Moine

Summary The Central Highland Granulites have been split into a cover assemblage of medium grade, little disturbed metasediments named the Grampian group, separated by a zone of sliding referred to as the Grampian Slide, from an underlying basement assemblage of high grade gneissose and migmatitic metasediments called the Central Highland Division. The Central Highland Division rocks are correlated on lithological, tectonic, metamorphic and radiometric grounds with the high grade Grenvillian rocks of the western Highland Moine, and are believed to represent their extension southeast of the Great Glen fault. The discovery of Precambrian ( c .720 Ma) pegmatites sheared by Caledonian (<570 Ma) sliding in the Central Highlands, enables the separation of Caledonian from Precambrian orogenic events in the rocks of both assemblages; their Precambrian orogenic history is so different, that the Central Highland Division rocks are considered to form a Grenvillian basement to the younger (Morarian) cover succession of the Grampian group. The western Highland Moine region is examined in the light of the tectonic cover-basement relationship postulated for the Central Highlands. The Loch Eil Division contains rock assemblages indistinguishable from the Central Highland Division, and others similar to the Grampian group. Evidence is put forward for a post Grenvillian, Morarian age for the Morar Division. The distribution of metamorphic zones in the Moine would seem to reflect the distribution of high grade basement and lower grade cover rocks, and may be in part determined by movements on a series of Caledonian slides, though this has not been demonstrated.

Regional geochemistry of the Northern Highlands of Scotland

Summary The distribution of trace-elements between the Lewisian basement and the Caledonian cover-formations can be assessed from regional geochemical maps based on stream-sediment sampling. The Lewisian basement is characterised by depletion in heat-producing elements, U, K, Rb, and in Pb, Be and by high values of Sr, Mg and first row transition elements. The range of Zr, Ba, B and Y levels are comparable with those over the Moine. Regional variations relate to crustal level and to the presence of zones of high deformation. Anomalies for Mo, Zr and U are associated with granite and pegmatites in some of these zones. Within the Moine nappe the zone of tectonically emplaced Lewisian slices divides an area where the bulk geochemistry is consistent with that of continental arkoses—the Morar Division—from the Glenfinnan and Loch Eil divisions which have geochemical characteristics closer to those of greywacke facies. No other geochemical discontinuity has been recognised in the Moine but the boundary with the Dalradian is marked by an increase in boron. Clear misfits of element distribution across the Great Glen fault are apparent but the data so far available could be interpreted in terms of either sinistral or dextral displacement.

Sea trout in North Argyll sea lochs: II. diet

The diet of sea trout in some of the sea lochs of the west coast of Scotland was investigated. The contents of 986 sea trout stomachs from the Loch Etive area (1970–1973), and 291 stomachs from the Loch Eil area (1964–1973), were examined and the composition of the diet, seasonal changes and the effect of trout size were analysed using frequency of occurrence, dry weight and number of organisms methods. Benthic feeding (crustacea and annelids) was more important in winter while midwater and surface organisms (young fish and insects) were preferred in summer. Young fish (mainly clupeids and sand eels) featured more in the diet of larger trout (≤21 cm) than in the smaller size range (≥21 cm). Surveys of 24‐h were completed in June and September, 1972, and indicated that availability of food was the main factor influencing the presence or absence of trout. Bottom feeding was greatest during the day while the amount of midwater and surface feeding tended to increase between sunset and sunrise.

The benthic ecology of Loch Linnhe and Loch Eil, a sea-loch system on the west coast of scotland. IV. Changes in the benthic fauna attributable to organic enrichment

Changes are described in the benthic fauna of Lochs Linnhe and Eil in response to organic enrichment of the loch sediments, brought about by the input of effluent material from a pulp and paper mill. Fluctuations in the amount of effluent discharges are related to subsequent successional changes in the fauna. As organic enrichment proceeds, there is progressive elimination of species, accompanied by an increase in the numbers of the surviving species. Excessive organic deposition leading to anoxic conditions at the sediment/water interface results in the elimination of all but a few annelid species. The observed successional changes are discussed in the light of recent hypotheses concerning ecological change in relation to environmental stress.

The benthic ecology of Loch Linnhe and Loch Eil, a sea-loch system on the west coast of Scotland. III. The effect on the benthic fauna of the introduction of pulp mill effluent

A five year survey of the macrobenthic fauna of Lochs Linnhe and Eil on the west coast of Scotland was undertaken to assess the effects on the fauna of the discharge of effluent from a pulp and paper mill into the narrows between the two lochs. Effluent discharge began early in 1966, and the survey covered the two years prior to this date and the subsequent years. The characteristics of the effluent are described. Variations in the total organic carbon content of the bottom sediments show little change over the period in the carbon levels at the deep-water stations, but show rises in the amounts at the shallowwater stations adjacent to the effluent outfall. The total biomass of the fauna at six regular sampling stations showed increases of between 13 and 62% in the three-year post-effluent period when compared with the pre-effluent period; however, the largest increases were recorded 1–2 years after introduction of effluent and the later samples showed a return to the biomass levels existing during the pre-effluent period. Variations in the numbers of the major molluscan and echinoderm species are analysed. A general increase in the numbers of the molluscs Corbula gibba (Olivi), Nucula sp. and Myrtea spinifera (Montagu) and the echinoderm Amphiura chiajei Forbes took place in the period September 1966 to July 1968, and were followed by a decline in the later months of 1968. Corbula gibba showed the rise earliest at the station at the head of Loch Eil where it had its highest resident populations, followed successively by rises at the station in mid-loch Eil and mid-loch Linnhe, and in 1968 it extended its range to the station furthest down Loch Linnhe. The feeding ecology of these species is discussed and the possible effect of the effluent on larval and adult stages are considered. It is concluded that, although following introduction of the effluent the successful larval settlement of the species considered may have been enhanced, the fluctuations observed are within the known range of benthic population changes, so that it seems unlikely that the introduction of effluent into the system has yet had any marked positive or negative effect on the benthic populations in the survey area.

A review of the structure and stratigraphy of the Moinian of Ardgour, Moidart and Sunart—Argyll and Inverness-shire

Synopsis The structural geometry is the result of four episodes of deformation (F 1 –F 4 ), with most major folds belonging to the second or third episodes. Major F 1 folds are probably absent (on stratigraphical evidence) but slides of the F 1 episode are not ruled out. Complex F 2 geometries—with curvilinear axes, and antiforms which turn into synforms when traced along traces—are found where F 2 folds are ‘folded’ by F 3 folds, and also remote from F 3 fold hinges. Intense inhomogeneous flattening explains these features, and it is considered that this flattening may be part of the second, rather than the third deformation. In the prevailing high-temperature conditions, the amount of flattening seems to be a function of rock-type and it is possible to distinguish between the simpler structures in thick psammites and the more complicated, highly flattened, structures in pelitic/striped rocks. The major rock units probably represent a stratigraphic sequence, from bottom to top, 1. Morar Division, 2. Glenfinnan Division and 3. Loch Eil Division.

The benthic ecology of Loch Linnhe and loch eil, a sea-loch system on the west coast of Scotland. I. The physical environment and distribution of the macrobenthic fauna

Loch Linnhe and Loch Eil form the inner part of an extensive sea-loch system on the west coast of Scotland. Brief descriptions of the topographical and hydrographical characteristics of the area are given together with information on the granulometry and total organic carbon content of the sediments. A detailed quantitative faunal list of the macrobenthic species is given and their distribution over twenty-four stations throughout the system is described. The fauna may be roughly sub-divided into four major groups: 1. 1) the deep-mud fauna, approximating to the Amphiura chiajei sub-community of the boreal Amphiura communities, 2. 2) the sandy-mud fauna, approximating to the Amphiura filiformis sub-community of the boreal Amphiura communities, 3. 3) the sand fauna, a mixture of species from the boreal Syndosmya and Venus communities, 4. 4) the gravel and pebble fauna, approximating to the Modiolus epifauna communities. There is considerable intermingling of these groups at many stations and, in addition, a number of ubiquitous species are predominant over a wide range of stations. It is concluded that distinct faunal communities do not exist in the system. Important environmental factors affecting the distribution of species are thought to be sediment-type, bottom current speed and, to a lesser extent, total organic content of the sediment. Depth appears to have little effect on distribution. Possible reasons for the blurring of distinctions between communities in enclosed and inshore areas are discussed.

A structural study of the granitic gneiss of Western Ardgour, Argyll and Inverness-shire

Synopsis The paper describes a structural study of part of the discontinuous belt of granitic gneiss extending from Glen Tarbert (Argyll) to north of Loch Quoich (Inverness-shire). The granitic gneiss outcrops immediately west of the boundary between the ‘highly inclined’ and ‘flat’ belts of the Moines (the Loch Quoich line) which is the eastern limit of outcrop of the regional migmatite belt (‘injection belt’). The Loch Eil psammitic belt (which constitutes the ‘flat’ belt) is the highest structural and stratigraphical unit of the area, overlying a thin pelitic horizon which rests on striped schists. Contrary to earlier correlations it is thought that all these units may overlie the classical Morar succession. Four main fold episodes (F1–F4) are recognisable. The granitic gneiss is entirely concordant, lies at the same horizon as the striped schists, and probably occupies the core of a tight F2 fold of highly variable plunge. Formation of the gneiss began prior to the second fold movement and it behaved during deformation as did the adjacent metasediments. The structural history of the gneiss is consistent with a migmatitic origin, and it was concentrated in a narrow belt by tectonic control.

On the Pre-Cambrian Rocks of the British Isles

Previous articleNext article FreeOn the Pre-Cambrian Rocks of the British IslesArchibald GeikieArchibald Geikie Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Journal of Geology Volume 1, Number 1Jan. - Feb., 1893 Article DOIhttps://doi.org/10.1086/606133 Views: 134Total views on this site Citations: 9Citations are reported from Crossref PDF download Crossref reports the following articles citing this article:Michael P. Searle Tectonic evolution of the Caledonian orogeny in Scotland: a review based on the timing of magmatism, metamorphism and deformation, Geological Magazine 159, no.11 (Oct 2021): 124–152.https://doi.org/10.1017/S0016756821000947John F. Dewey, Ian W. D. Dalziel, R. John Reavy, Rob A. Strachan The Neoproterozoic to Mid-Devonian evolution of Scotland: a review and unresolved issues, Scottish Journal of Geology 51, no.11 (Mar 2015): 5–30.https://doi.org/10.1144/sjg2014-007A. Graham Leslie, Martin Smith, N.J. Soper Laurentian margin evolution and the Caledonian orogeny—A template for Scotland and East Greenland, (Jan 2008): 307–343.https://doi.org/10.1130/2008.1202(13)Peter A. Cawood, Alexander A. Nemchin, Rob A. Strachan, Peter D. Kinny, Staci Loewy Laurentian provenance and an intracratonic tectonic setting for the Moine Supergroup, Scotland, constrained by detrital zircons from the Loch Eil and Glen Urquhart successions, Journal of the Geological Society 161, no.55 (Jun 2022): 861–874.https://doi.org/10.1144/16-764903-117Peter A. Cawood, Alexander A. Nemchin, Martin Smith, Staci Loewy Source of the Dalradian Supergroup constrained by U–Pb dating of detrital zircon and implications for the East Laurentian margin, Journal of the Geological Society 160, no.22 (Mar 2003): 231–246.https://doi.org/10.1144/0016-764902-039C.R.L. Friend, R.A. Strachan, P.D. Kinny, G.R. Watt Provenance of the Moine Supergroup of NW Scotland: evidence from geochronology of detrital and inherited zircons from (meta)sedimentary rocks, granites and migmatites, Journal of the Geological Society 160, no.22 (Mar 2003): 247–257.https://doi.org/10.1144/0016-764901-161N. J. SOPER, A. L. HARRIS, R. A. STRACHAN Tectonostratigraphy of the Moine Supergroup: a synthesis, Journal of the Geological Society 155, no.11 (Jan 1998): 13–24.https://doi.org/10.1144/gsjgs.155.1.0013N. J. SOPER, R. W. ENGLAND Vendian and Riphean rifting in NW Scotland, Journal of the Geological Society 152, no.11 (Jan 1995): 11–14.https://doi.org/10.1144/gsjgs.152.1.0011D.R. Oldroyd The Archaean controversy in Britain: Part I—The Rocks of St David's, Annals of Science 48, no.55 (Aug 2006): 407–452.https://doi.org/10.1080/00033799100200501