Collins Bay Research Articles

Tracking suspended particulate organic matter biochemistry from glacial meltwater runoff to coastal waters of an Antarctic fjord

Increased glacier melting runoff in Antarctica involves intensification of freshwater, nutrients, sediments and organic matter inputs from land to the sea, which is impacting coastal ecosystems. Basic environmental characteristics of water and biochemical composition of suspended particulate organic matter (POM) both in the proglacial melting runoff system (PROGLARS) of Collins Glacier and marine surface waters of Collins Bay was studied based on organic biopolymers and molecular level analysis of amino acids (AAs), to discern among sources and degradation state in the two environments. Hierarchical Clustering Analysis revealed that PROGLARS stations and marine stations form two distinct groups in terms of water physicochemical characteristics and suspended POM biochemical composition. These differences are the consequence of low restricted contribution of freshwater from Collins Glacier runoff into the coastal-marine environment. Our results evidenced low concentrations of terrestrial suspended POM in marine waters of Collins Bay mainly attributed to low meltwater inputs between the 1st and 7th of February 2018. In terms of macromolecular composition, the predominance of proteins, denote the labile nature of suspended POM in the two environments. Suspended POM in Collins Bay is labile, poorly degraded, representing a protein supplemented food resource, with high energetic value and easily assimilated by heterotrophic marine organism. AAs composition supported less degraded suspended POM derived from marine phytoplankton in surface waters of Collins Bay, whereas, great degradation of suspended POM in the proglacial runoff system of Collins Glacier. Changes in the biochemistry of suspended POM caused by glacial melting and retreat, may affect food features and availability, the productivity of ecosystems, and ultimately, the capacity of Antarctic fjords to act as carbon sinks and climate regulators. Considering low influence of Collins Glacier meltwater in coastal marine waters of Collins Bay, due to the relatively slow retreat of Collins Glacier and low development of its meltwater runoff system, the results of our work are relevant as baseline information for comparison with other Antarctic fjords. Further knowledge about meltwater runoff and suspended POM input dynamics in Antarctic coastal ecosystems, is critical, particularly in areas prone to undergo increased glacier melting in the following decades.

Biogeochemical and oceanographic conditions provide insights about current status of an Antarctic fjord affected by relatively slow glacial retreat.

Understand the origin, transport, and character of organic matter entering Antarctic fjords is essential as they are major components of the global carbon cycle and budget. Macromolecular pools of particulate organic matter, bulk organic geochemistry, major and trace elements in surface sediments from Collins Bay were analysed as source indicators. Oceanographic conditions, bathymetry (multibeam) and grain size were considered as environmental controlling factors. Sediment samples were taken with a van Veen grab, during the ANTAR XXV Peruvian expedition (February 2018), onboard the R/V "BAP Carrasco" from the Peruvian Navy. Biopolymeric composition revealed the predominance of fresh marine protein-rich organic matter in the seafloor of Collins Bay, denoting high quality food resource for marine benthic heterotrophs. Based on Igeo values (between 0 and 1) Collins Bay can be considered unpolluted with natural levels of As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn. Distribution of most of these elements with a gradient of decrease from the shallow inner fjord towards the outer deepest fjord, suggest their association with the deposition of detrital material and lithogenic particles supplied by Collins Glacier frontal ablation and runoff. This first comprehensive baseline information would assist in interpreting downcore sedimentary reconstructions and future climate-induce changes.

Oceanographic and climatic influences on Trooz Glacier, Antarctica during the Holocene

To evaluate the significance of recent widespread glacial recession in the Antarctic Peninsula, it is imperative to extend the limited instrumented record of glacier change with long sedimentary archives of the Holocene. Reconstructing glacial histories that capture the variability of environments in the Antarctic Peninsula will enable better constraint of ocean and climate forcings on regional glacial stability. Two sediment cores are analyzed from the 2007 RV/IB N.B. Palmer cruise to Collins Bay, the embayment immediately offshore Trooz Glacier on the Graham Land coast, and provide an archive to test controls on long-term stability of outlet glaciers in an open bay setting. Radiocarbon and Lead-210 (a short-lived radioisotope) age-depth models provide a timeline for Trooz Glacier behavior and associated oceanographic changes over the last 10,000 years.Magnetic susceptibility, grain size, diatom assemblage, total organic carbon, nitrogen, and stable isotopes of organic carbon are utilized as proxies for changing glacial and ocean conditions. Outer Collins Bay deglaciated by ∼10000 cal yr B.P. Diatom abundance and organic content signal productivity increase during further glacial recession from ∼8900 to 6100 cal yr B.P., which coincided with upwelling of relatively warm Circumpolar Deep Water into the bay. High productivity, characterized by Thalassiosira antarctica-dominated diatom assemblages with prominence of Fragilariopsis kerguelensis, indicate open marine conditions with incursion of offshore currents into the bay from ∼6100 to 760 cal yr B.P. A sharp decrease in organic content, diatom abundance, and grain size indicate more sea ice and ice-tongue/ice-canopy advance from ∼760 to 240 cal yr B.P., when the floating ice canopy in outer Collins Bay retreated to near its present-day position and productivity increased. During the period of the 1950's to 1990's, Trooz Glacier was one of only two Antarctic Peninsula glaciers that advanced slightly. Over the Holocene, oceanographic forcing dominated the long-term stability of Trooz Glacier due to its open aspect, and it is unknown how Trooz Glacier will respond to continued influence of Circumpolar Deep Water in the future. Understanding ocean forcings on glacial stability, together with other local controls like drainage basin configuration and bay geometry, should help contextualize the modern retreat and improve prediction of glacial response to prevalent Circumpolar Deep Water circulation in this dynamic region.

Between-summer comparison of particulate organic matter in surface waters of a coastal area influenced by glacier meltwater runoff and retreat

We evaluated, in two consecutive austral summers, the biochemical composition, sources, distribution and degradation state of particulate organic matter (POM) in surface coastal waters of Collins Bay, King George Island, Antarctica. Bulk elemental and stable isotope analyses were combined with molecular-level proxies (fatty acids and amino acids) to obtain more comprehensive evidence about POM characteristics. Two different settings were recognized. In February 2016, there was a reduced glacier melting condition and meltwater runoff due to cold weather. Marine fresh phytoplankton and ice-associated POM with the dominance of diatoms, bacteria, zooplankton and ice-associated fauna were the major components of POM. In contrast, in January 2017 under increased glacier melting and meltwater runoff due to warm weather conditions, suspended POM was constituted by marine phytoplankton, Rhodophyta macroalgae detritus and an increased terrestrial contribution. The lower degradation state of suspended POM in February 2016 than in January 2017 and the early bacterial response to the input of fresh protein-rich organic matter derived from marine phytoplankton, mainly diatoms, was supported. Our results provide evidence of the negative impact of glacier retreat and increased meltwater runoff on POM features in Collins Bay, which can be relevant to other Antarctic coastal marine ecosystems.

Correction to: Influence of summer conditions on surface water properties and phytoplankton productivity in embayments of the South Shetland Islands

Phytoplankton productivity in glaciomarine embayments of the West Antarctic Peninsula is constrained because of extensive thermohaline variability, which is due to seasonal sea-ice and glacial melting. To determine whether or not this affects the biology of the water column, we explored the influence of surface water properties on phytoplankton productivity in four embayments of the South Shetland Islands (SSI) during late summer of 2013. We analyzed hydrographic, climatic, and primary productivity satellite data (wind velocity, sea-ice cover, and chlorophyll-a), in situ CTD measurements of physical and chemical characteristics, new estimates of net primary production (NPP), and surface water samples for chlorophyll-a, nutrients, biogenic silica, and plankton composition. Sea-ice cover at the SSI was ~ 20% during February. Long-term satellite wind data (2010–2015) showed that during February 2013 the average wind velocity was ~ 2 m s−1 higher than the long-term mean with two low sea surface temperature events occurring simultaneously at all sites. The CTD profiles did not show vertical salinity changes, although salinity was highly correlated with the percentage of integrated nanoplankton Chl-a, which represented > 50% of the total integrated Chl-a in all the embayments. Phytoplankton was the major contributor to the integrated carbon biomass of the upper water column, where centric diatoms predominated. The contribution of microzooplankton and bacterioplankton at the different sites explained NPP values and the trophic mode at each site. Specifically, NPP at Fildes Bay exhibited an autotrophic productivity mode in contrast to Collins Bay, where both heterotrophic and autotrophic modes alternated, mainly due to weekly changes in community respiration rates.

Patterns of skin disease in a sample of the federal prison population: a retrospective chart review.

Dermatology in vulnerable populations is under-researched. Our objective was to analyze the most commonly referred skin diseases affecting the Correctional Service Canada inmates in Ontario. An observational, cross-sectional, retrospective chart review of inmate patients seen from 2008 until 2013 was performed. Two groups of patients were included in the analysis: those assessed in-person, and those evaluated by e-consult. In the in-person patient group, the 3 most common diagnoses were acne, psoriasis and other superficial mycoses. For the e-consult group, the 3 most frequent diagnoses were acne, psoriasis and rosacea. There was a clear bias toward more inmates being seen in-person where the service was provided (Collins Bay Institution) than from other correctional institutions in Eastern Ontario. Most of the skin diseases that affected the incarcerated population studied were common afflictions, similar to those affecting the general population, which is in agreement with other studies. Future studies investigating skin diseases in male and female inmates across Canada would bestow more generalizable data.

Species diversity and changes of communities of heterotrophic flagellates (protista) in response to glacial melt in King George Island, the South Shetland Islands, Antarctica

AbstractGlacial melt has a great influence on biological communities of the Antarctic Peninsula. Annual changes in heterotrophic flagellates from March 2008–March 2009 and effects of glacial melting on heterotrophic flagellates from December 2008–March 2009 were studied within the coastal zone of King George Island. The maximum abundance and biomass occurred in November and December (950.6–1236.2 individuals ml-1; 0.02–0.035 μg C ml-1), and the minimum in May and June (419.8–456.8 individuals ml-1; 0.018–0.019 μg C ml-1). Forty-five species were identified. The diversity of choanoflagellates, euglenids, bicosoecids, kinetoplastids and incertae sedis flagellates was greatest. Glacial melt between December and April resulted in the freshening of the surface water at the Collins Bay, giving rise to a vertical gradient of salinity (from 26‰ at the surface to 34‰ at the near-bottom layer). The trophic, size and species structure of the heterotrophic flagellates was simplified due to freshening of the surface waters. Eurybiontic and cosmopolitan species were significantly enriched in the freshened surface layer, with prevalence of small-sized mobile bacterio-detritovorous forms. The simplification of structure of the assemblage of heterotrophic flagellates can affect the stability of biological communities.

Distribution and dispersal pattern of suspended particulate matter in Maxwell Bay and its tributary, Marian Cove, in the South Shetland Islands, West Antarctica

Water property casting data (SPM and CTDT) have been obtained from ice-influenced fjords, Maxwell Bay and Marian Cove, in the South Shetland Islands, Antarctica to describe the configuration of turbid meltwater plumes in detail and to elucidate the dispersal pattern of the plumes in the areas. Of the primary sediment pathways, only ice-contact processes are unique in ice-influenced fjords. The effect of glaciofluvial discharges has been overwhelmed by the influences of subglacial discharge and ice-front melting. Fluvial discharge from side-entry glaciers that commonly end on land and/or supraglacial discharge from ice surface are, however, more responsible for the overflow plumes in Maxwell Bay and Marian Cove. Subglacial meltwater discharge, which is almost always in the form of vertically rising buoyant jets, is considered rare. Active glaciofluvial and/or supraglacial input from Marian Cove causes most suspended particulate matter to be concentrated near the mid-point of Maxwell Bay. Thus, even though closer to fjord-head trunk glaciers, SPM concentration in Collins Bay is comparatively low, largely due to clean tidewater glaciers and absence of meltwater streams around Collins Bay. Strong bottom current flowing along the continental shelf off the South Shetland Islands may import and export sediment from the outside of Maxwell Bay, influencing the distribution of bottom sediment as well as benthic community.

The application of laser ablation microprobe-inductively coupled plasma-mass spectrometry (LAM-ICP-MS) to in situ (U)Pb geochronology

The direct dating of single pitchblende and zircon grains is reported, using a laser ablation microprobe (LAM) which has been coupled to a commercial inductively coupled plasma-mass spectrometer (ICP-MS). The system has been designed for micro sampling minerals in petrographic sections. Major advantages of this technique, compared to other in situ dating techniques, are the: (1) separation of the sampling process from the excitation (dissociation and ionization) processes; (2) minimal complex and variable ion species in the mass analyzer; (3) ability to monitor and adjust the analysis characteristics during ablation; (4) ease of isolation and analysis of the isotopic data at all stages during an ablation sampling; (5) ability to date diverse materials; and (6) relatively low capital costs. Direct dating of uranium-rich phases such as pitchblende is rapid, precise and requires no chemical pretreatment. The ability to analyze small areas (diameters of 20–30 μm) facilitates studies on the timing of primary and secondary U mineralization. Micro sampling of an individual pitchblende grain from the complex Collins Bay uranium deposit in Saskatchewan, Canada, illustrates this new technique's potential and the equivalence of conventional and LAM-ICP-MS age determinations. Analysis of 100-μm-diameter late Archean zircons further demonstrates that LAM-ICP-MS has the potential to become a rival of competing techniques for regional reconnaissance and sediment provenance age studies. In addition, this technique is uniquely capable of providing simultaneous monitoring of chemical and isotopic homogeneity during analysis of accessory minerals used in UPb geochronology.

The age of unconformity-related uranium mineralization in the Athabasca Basin, northern Saskatchewan

Age data are presented for major Athabasca Basin uranium deposits at Cigar Lake, Cluff Lake, Collins Bay, Dawn Lake, Eagle Point, McArthur River, Midwest, and Rabbit Lake, as well as for several minor or undeveloped deposits, including Hughes Lake and Nisto. The best constrained data indicate that almost all the deposits formed in a restricted time interval between about 1330 and 1380 Ma. This range of ages is believed to be real and not the result of uncertainties in the calculation of ages based on discordant data. The one major exception is the recently discovered NiAs-free deposit at McArthur River, for which a well-determined age of 1514 ± 18 Ma (2σ) has been obtained. Even this deposit yields an age in the1330–1380 Ma range for some material. Periods of reworking–redeposition occurred at ~1280, ~1000, ~575, and ~225 Ma. These may be basin-wide, affecting to some degree all the deposits that we have studied. Other times of redeposition are less well determined, but may be present as well. No ages that approach the ~1700 Ma age of the Athabasca Group have been found to date for unconformity-related deposits, and the Athabasca Basin mineralization is unrelated to the ~1750 Ma pitchblende vein deposits in the Beaverlodge Lake area.

Laser probe 40Ar/39Ar and conventional K/Ar dating of illites associated with the McClean unconformity-related uranium deposits, north Saskatchewan, Canada

The McClean group of uranium deposits consists of elongate pods of high-grade uranium mineralization (width = ~ 15–40 m) tightly confined to within ±40 m of the basal unconformity. Uraninite–coffinite–sulphide/arsenide–chlorite–siderite mineralization at McClean is surrounded by a muscovite/illite ± haematite hydrothermal alteration halo,which can contain coffinite–pararammelsbergite (NiAs2) – muscovite/illite nodules. Ten laser probe 40Ar/39Ar dates, two of which are step-heat runs showing good plateaus, and 10 conventional K – Ar dates for this material show a distribution with asharp beginning at ~ 1320 Ma, a marked peak in the 1250–1200 Ma class interval, and a tail to dates as young as 1002 ± 33 (1σ) Ma. These determinations are in complete agreement with direct (U–Pb and Sm–Nd) dates on uraninite at the Midwest (e.g., 1328 ± 9 and 1110 ± 28 Ma), Key Lake (e.g., 1350 ± 4 and 1281 ± 6 Ma), and Collins Bay B deposits(e.g., 1281 ± 80 Ma). Since estimated depositional ages for the Athabasca sedimentary sequence are in the 1470 ± 15 to1428 ± 15 Ma range, uranium mineralization and associated hydrothermal alteration started ~ 100–150 Ma after Athabasca sedimentation, a result consistent with fluid-inclusion data, which indicate that mineralization took place at ~ 160–220 °C beneath ~ 3000 m of cover at a relatively advanced stage in the evolution of the basin. It is suggested that the similar initiation dates for uranium mineralization might reflect a widespread faulting event that affected the eastern part of the basin. A muscovite/illite closure temperature calculated from a measured argon diffusion activation energy of 36 ± 4 kcal/mol(1 kcal = 4.1868 kJ) indicates that the base of the Athabasca Basin in the McClean area has not been disturbed by temperatures greater than ~ 140 °C for 1.1–1.0 Ga. It is suggested that mineralization ceased when fracture permeability had been sealed by crystallization of secondary minerals. The duration of mineralization may have been ~ 150 Ma, a relatively long time interval not unreasonable for the base of a sedimentary basin.Secondary illites interstitial to quartz grains from the HLM1 stratigraphic borehole give 40Ar/39Ar ages of 1459 ± 4, 1341 ± 4, and 1113 ± 11 Ma, indicating that formation of diagenetic sheet silicates predated uranium mineralization. Recrystallization or formation of sheet silicates in relict sedimentary layers and in subunconformity altered basement referred to as "regolith" started at approximately the same time, since dates of 1484 ± 55 Ma (sedimentary layer), 1482 ± 49 Ma (regolith), and 1453 ± 49 Ma (regolith) have been obtained. Resetting of interstitial, sedimentary layer, and regolith sheet-silicate dates continued to ages of, for example, 1113 ± 11 Ma (interstitial) and 1038 ± 55 Ma (sedimentary layer), which exactly coincide with the youngest ages obtained for the alteration halo associated with mineralization.The youngest date obtained is a 40Ar/39Ar plateau age of 673 ± 3 Ma. The sample (2045-517) was obtained from within 2 mm of a concentrated pitchblende nodule and may have been disturbed in some way by its proximity to uranium.

Comment and Reply on “Sm-Nd direct dating of the Collins Bay hydrothermal uranium deposit, Saskatchewan”

Comment and Reply on “Sm-Nd direct dating of the Collins Bay hydrothermal uranium deposit, Saskatchewan”

Comment and Reply on “Sm-Nd direct dating of the Collins Bay hydrothermal uranium deposit, Saskatchewan”

Comment and Reply on “Sm-Nd direct dating of the Collins Bay hydrothermal uranium deposit, Saskatchewan”

Sm-Nd direct dating of the Collins Bay hydrothermal uranium deposit, Saskatchewan

Primary pitchblende mineralization from the Collins Bay unconformity-type uranium deposit in northern Saskatchewan has been dated using the Sm-Nd method. The mineral isochron age of 1281 +/- 80 Ma is in good agreement with other geologic and geochronological data, and demonstrates the potential of the Sm-Nd technique for the direct dating of hydrothermal mineral deposits. 23 references, 5 figures, 7 tables.