Sedimentation of Organic Matter in St. Margaret’s Bay, Nova Scotia

1975 ◽  
Vol 32 (8) ◽  
pp. 1399-1407 ◽  
Author(s):  
T. J. M. Webster ◽  
Madhu A. Paranjape ◽  
K. H. Mann
Keyword(s):  
Organic Matter ◽  
Nova Scotia ◽  
Bottom Sediment ◽  
Shallow Water ◽  
Inorganic Material ◽  
Sediment Traps ◽  
Total Catch ◽  
Deep Station ◽  
Probable Source ◽  
Shallow Station

Sediment traps were placed at two sites in St. Margaret’s Bay. At a deep station (70 m), traps were placed 5 m and 10 m above the bottom; at a shallow station (10 m), six traps were placed between 45 and 197 cm above the bottom. Total catch averaged 118 g C m−2yr−1 at the deep station and 134 g C m−2yr−1 at the shallow station. The most probable source of the organic matter was detritus derived from seaweeds and seagrasses, but the most probable source of inorganic material was bottom sediment. It is suggested that the traps were taking bottom sediment resuspended from shallow water, enriched by detritus from seaweeds and seagrasses.

scholarly journals Programmed cell death in diazotrophs and the fate of organic matter in the western tropical South Pacific Ocean during the OUTPACE cruise

2018 ◽  
Vol 15 (12) ◽  
pp. 3893-3908 ◽  
Author(s):  
Dina Spungin ◽  
Natalia Belkin ◽  
Rachel A. Foster ◽  
Marcus Stenegren ◽  
Andrea Caputo ◽  
...  
Keyword(s):  
Cell Death ◽  
Organic Matter ◽  
Pacific Ocean ◽  
Programmed Cell Death ◽  
South Pacific ◽  
Sediment Traps ◽  
Vertical Flux ◽  
Filamentous Cyanobacterium ◽  
Chl A ◽  
South Pacific Ocean

Abstract. The fate of diazotroph (N2 fixers) derived carbon (C) and nitrogen (N) and their contribution to vertical export of C and N in the western tropical South Pacific Ocean was studied during OUTPACE (Oligotrophy to UlTra-oligotrophy PACific Experiment). Our specific objective during OUTPACE was to determine whether autocatalytic programmed cell death (PCD), occurring in some diazotrophs, is an important mechanism affecting diazotroph mortality and a factor regulating the vertical flux of organic matter and, thus, the fate of the blooms. We sampled at three long duration (LD) stations of 5 days each (LDA, LDB and LDC) where drifting sediment traps were deployed at 150, 325 and 500 m depth. LDA and LDB were characterized by high chlorophyll a (Chl a) concentrations (0.2–0.6 µg L−1) and dominated by dense biomass of the filamentous cyanobacterium Trichodesmium as well as UCYN-B and diatom–diazotroph associations (Rhizosolenia with Richelia-detected by microscopy and het-1 nifH copies). Station LDC was located at an ultra-oligotrophic area of the South Pacific gyre with extremely low Chl a concentration (∼ 0.02 µg L−1) with limited biomass of diazotrophs predominantly the unicellular UCYN-B. Our measurements of biomass from LDA and LDB yielded high activities of caspase-like and metacaspase proteases that are indicative of PCD in Trichodesmium and other phytoplankton. Metacaspase activity, reported here for the first time from oceanic populations, was highest at the surface of both LDA and LDB, where we also obtained high concentrations of transparent exopolymeric particles (TEP). TEP were negatively correlated with dissolved inorganic phosphorus and positively coupled to both the dissolved and particulate organic carbon pools. Our results reflect the increase in TEP production under nutrient stress and its role as a source of sticky carbon facilitating aggregation and rapid vertical sinking. Evidence for bloom decline was observed at both LDA and LDB. However, the physiological status and rates of decline of the blooms differed between the stations, influencing the amount of accumulated diazotrophic organic matter and mass flux observed in the traps during our experimental time frame. At LDA sediment traps contained the greatest export of particulate matter and significant numbers of both intact and decaying Trichodesmium, UCYN-B and het-1 compared to LDB where the bloom decline began only 2 days prior to leaving the station and to LDC where no evidence for bloom or bloom decline was seen. Substantiating previous findings from laboratory cultures linking PCD to carbon export in Trichodesmium, our results from OUTPACE indicate that nutrient limitation may induce PCD in high biomass blooms such as displayed by Trichodesmium or diatom–diazotroph associations. Furthermore, PCD combined with high TEP production will tend to facilitate cellular aggregation and bloom termination and will expedite vertical flux to depth.

Gametogenesis and the reproductive cycle in the deep-sea anemone Paracalliactis stephensoni (Cnidaria: Actiniaria)

1990 ◽  
Vol 70 (1) ◽  
pp. 163-172 ◽  
Author(s):  
Michel Praet-Van
Keyword(s):  
Organic Matter ◽  
Shallow Water ◽  
Deep Sea ◽  
Phytoplankton Bloom ◽  
Sea Anemone ◽  
Bay Of Biscay ◽  
Sea Anemones ◽  
Spring Phytoplankton Bloom ◽  
Sea Floor ◽  
Ultrastructural Investigation

This ultrastructural investigation of gametogenesis in a deep-sea anemone of the Bay of Biscay trawled around 2000 m depth, contributes to the knowledge of biology and strategy of reproduction of deep-sea benthos.This sea anemone is dioecious. The sperm appears very similar to those of shallow water sea anemones of the genus, Calliactis. The ultrastructural investigation of oogenesis allows the characteristics of the stages of previtellogenesis and vitellogenesis to be defined. The latter begins with a period of lipogenesis correlated with the formation of a trophonema. Mature oocytes measure up to 180 (im in diameter. Study of spermatogenesis and oogenesis reveals that spawning occurs in April/May. In males, the main area of testicular cysts, full of sperm, reaches maximal development from March to May and, in females, the percentage of mature oocytes decreases from 33% in April to 1% in May.Spawning may be induced by the advent in the deep-sea of the products of the spring phytoplankton bloom. This period of spawning, during the increased deposition of organic matter to the deep-sea floor, may be an advantageous strategy for early development of Paracalliactis.

scholarly journals Paleoenvironment of the Lower–Middle Cambrian Evaporite Series in the Tarim Basin and Its Impact on the Organic Matter Enrichment of Shallow Water Source Rocks

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 659
Author(s):  
Mingyang Wei ◽  
Zhidong Bao ◽  
Axel Munnecke ◽  
Wei Liu ◽  
G. William M. Harrison ◽  
...  
Keyword(s):  
Organic Matter ◽  
Shallow Water ◽  
Tarim Basin ◽  
Water Environment ◽  
Water Source ◽  
Major Elements ◽  
Source Rocks ◽  
Middle Cambrian ◽  
Sedimentary Environments ◽  
The Impact

Just as in deep-water sedimentary environments, productive source rocks can be developed in an evaporitic platform, where claystones are interbedded with evaporites and carbonates. However, the impact of the paleoenvironment on the organic matter enrichment of shallow water source rocks in an evaporite series has not been well explored. In this study, two wells in the central uplift of the Tarim Basin were systematically sampled and analyzed for a basic geochemical study, including major elements, trace elements, and total organic carbon (TOC), to understand the relationship between TOC and the paleoenvironmental parameters, such as paleosalinity, redox, paleoclimate, paleo-seawater depth, and paleoproductivity. The results show that the Lower–Middle Cambrian mainly developed in a fluctuating salinity, weak anoxic to anoxic, continuous dry and hot, and proper shallow water environment. The interfingering section of evaporites, carbonates, and claystones of the Awatag Fm. have higher paleoproductivity and higher enrichment of organic matter. Paleosalinity, redox, paleoclimate, paleo-seawater depth, and paleoproductivity jointly control the organic matter enrichment of shallow water source rocks in the evaporite series. The degree of enrichment of organic matter in shallow water source rocks first increases and then decreases with the increase in paleosalinity. All the samples with high content of organic matter come from the shallower environment of the Awatag Fm.

scholarly journals Spatiotemporal variability of sedimentary organic matter supply and recycling processes in coral reefs of Tayrona National Natural Park, Colombian Caribbean

2014 ◽  
Vol 11 (11) ◽  
pp. 2977-2990 ◽  
Author(s):  
E. Bayraktarov ◽  
C. Wild
Keyword(s):  
Organic Matter ◽  
Coral Reef ◽  
Coastal Upwelling ◽  
Sediment Traps ◽  
Sedimentary Organic Matter ◽  
Spatiotemporal Variability ◽  
Water Current ◽  
Labile Organic Matter ◽  
Natural Park ◽  
River Mouths

Abstract. Sediments are fundamental for the function of oligotrophic coral reef ecosystems because they are major places for organic matter recycling. The Tayrona National Natural Park (TNNP, Colombian Caribbean) is located between the population center Santa Marta (>455 000 inhabitants) in the southwest and several river mouths in the east. Here, coral reef sediments experience pronounced changes in environmental conditions due to seasonal coastal upwelling, but knowledge of relevant spatiotemporal effects on organic matter supply to the sediments and recycling processes is not available. Therefore, sediment traps were deployed monthly over 14 months complemented by assessment of sedimentary properties (e.g., porosity, grain size, content of particulate organic matter and pigments) and sedimentary O2 demand (SOD) at water-current-exposed and sheltered sites along distance gradients (12–20 km) to Santa Marta and the eastern river mouths (17–27 km). Findings revealed that seasonal upwelling delivered strong (75–79% of annual supply) pulses of labile organic matter mainly composed of fresh phytoplankton detritus (C : N ratio 6–8) to the seafloor. Sedimentary chlorophyll a contents and SOD increased significantly with decreasing distance to the eastern rivers, but only during upwelling. This suggests sedimentary organic matter supply controlled by nutrient-enriched upwelling waters and riverine runoff rather than by the countercurrent-located city of Santa Marta. Organic matter pulses led to significantly higher SOD (more than 30%) at the water-current-sheltered sites as compared to the exposed sites, ensuing a rapid recycling of the supplied labile organic matter in the permeable silicate reef sands.

scholarly journals Sediment-water column fluxes of carbon, oxygen and nutrients in Bedford Basin, Nova Scotia, inferred from <sup>224</sup>Ra measurements

2013 ◽  
Vol 10 (1) ◽  
pp. 53-66 ◽  
Author(s):  
W. J. Burt ◽  
H. Thomas ◽  
K. Fennel ◽  
E. Horne
Keyword(s):  
Organic Matter ◽  
Nova Scotia ◽  
Water Column ◽  
Explicit Knowledge ◽  
Dissolved Inorganic Carbon ◽  
Chemical Constituents ◽  
Water Interface ◽  
Benthic Fluxes ◽  
Pore Waters ◽  
Overlying Water

Abstract. Exchanges between sediment pore waters and the overlying water column play a significant role in the chemical budgets of many important chemical constituents. Direct quantification of such benthic fluxes requires explicit knowledge of the sediment properties and biogeochemistry. Alternatively, changes in water-column properties near the sediment-water interface can be exploited to gain insight into the sediment biogeochemistry and benthic fluxes. Here, we apply a 1-D diffusive mixing model to near-bottom water-column profiles of 224Ra activity in order to yield vertical eddy diffusivities (KZ), based upon which we assess the diffusive exchange of dissolved inorganic carbon (DIC), nutrients and oxygen (O2), across the sediment-water interface in a coastal inlet, Bedford Basin, Nova Scotia, Canada. Numerical model results are consistent with the assumptions regarding a constant, single benthic source of 224Ra, the lack of mixing by advective processes, and a predominantly benthic source and sink of DIC and O2, respectively, with minimal water-column respiration in the deep waters of Bedford Basin. Near-bottom observations of DIC, O2 and nutrients provide flux ratios similar to Redfield values, suggesting that benthic respiration of primarily marine organic matter is the dominant driver. Furthermore, a relative deficit of nitrate in the observed flux ratios indicates that denitrification also plays a role in the oxidation of organic matter, although its occurrence was not strong enough to allow us to detect the corresponding AT fluxes out of the sediment. Finally, comparison with other carbon sources reveal the observed benthic DIC release as a significant contributor to the Bedford Basin carbon system.

scholarly journals Amino acid composition and <i>δ</i><sup>15</sup>N of suspended matter in the Arabian Sea: implications for organic matter sources and degradation

2013 ◽  
Vol 10 (11) ◽  
pp. 7689-7702 ◽  
Author(s):  
B. Gaye ◽  
B. Nagel ◽  
K. Dähnke ◽  
T. Rixen ◽  
N. Lahajnar ◽  
...  
Keyword(s):  
Organic Matter ◽  
Amino Acid ◽  
Water Column ◽  
Residence Time ◽  
Mixed Layer ◽  
Suspended Matter ◽  
Arabian Sea ◽  
Monsoon Season ◽  
Sediment Traps ◽  
Surface Mixed Layer

Abstract. Sedimentation in the ocean is fed by large aggregates produced in the surface mixed layer that sink rapidly through the water column. These particles sampled by sediment traps have often been proposed to interact by disaggregation and scavenging with a pool of fine suspended matter with very slow sinking velocities and thus a long residence time. We investigated the amino acid (AA) composition and stable nitrogen isotopic ratios of suspended matter (SPM) sampled during the late SW monsoon season in the Arabian Sea and compared them to those of sinking particles to understand organic matter degradation/modification during passage through the water column. We found that AA composition of mixed layer suspended matter corresponds more to fresh plankton and their aggregates, whereas AA composition of SPM in the sub-thermocline water column deviated progressively from mixed layer composition. We conclude that suspended matter in deep waters and in the mixed layers of oligotrophic stations is dominated by fine material that has a long residence time and organic matter that is resistant to degradation. SPM in areas of high primary productivity is essentially derived from fresh plankton and thus has a strong imprint of the subsurface nitrate source, whereas SPM at oligotrophic stations and at subthermocline depths appears to exchange amino acids and nitrogen isotopes with the dissolved organic carbon (DOC) pool influencing also the δ15N values.

scholarly journals Modulation of the vertical particles transfer efficiency in the Oxygen Minimum Zone off Peru

2018 ◽  
Author(s):  
Marine Bretagnon ◽  
Aurélien Paulmier ◽  
Véronique Garçon ◽  
Boris Dewitte ◽  
Sérena Illig ◽  
...  
Keyword(s):  
Organic Matter ◽  
Water Column ◽  
Sediment Traps ◽  
Biogeochemical Cycles ◽  
High Temporal Resolution ◽  
Oxygen Minimum Zones ◽  
Marine Life ◽  
Minimum Zone ◽  
Earth’S System ◽  
Oxygen Minimum

Abstract. The fate of the Organic Matter (OM) produced by marine life controls the major biogeochemical cycles of the Earth’s system. The OM produced through photosynthesis is either preserved, exported towards sediments or degraded through remineralisation in the water column. The productive Eastern Boundary Upwelling Systems (EBUSs) associated with Oxygen Minimum Zones (OMZs) should foster OM preservation due to low O2 conditions, but their intense and diverse microbial activity should enhance OM degradation. To investigate this contradiction, sediment traps were deployed near the oxycline and in the OMZ core on an instrumented moored line off Peru, providing high temporal resolution O2 series characterizing two seasonal steady states at the upper trap: suboxic ([O2] 

Study of Organic Matter in Recent Sediments Southeast of Halifax, Nova Scotia

1964 ◽  
Author(s):  
L H King
Keyword(s):  
Organic Matter ◽  
Nova Scotia ◽  
Recent Sediments

Chlorinated Organic Contaminants on suspended Sediments in Lake St. Clair

1986 ◽  
Vol 21 (3) ◽  
pp. 380-389 ◽  
Author(s):  
Murray N. Charlton ◽  
Barry G. Oliver
Keyword(s):  
Bottom Sediment ◽  
Organic Contaminants ◽  
Lake Erie ◽  
Suspended Sediments ◽  
Sediment Traps ◽  
Transboundary Pollution ◽  
Suspended Material ◽  
Chlorinated Organic ◽  
Lateral Mixing ◽  
Thames River

Abstract Sediment traps were used to study the presence and fate of chlorinated organics on suspended material in Lake St. Clair. The bulk of the material caught by the traps was resuspended bottom sediment. The highest concentrations of organics were usually found in the center of the lake while the lowest concentrations were found in the southeast area near the Thames River outlet. Organic contaminants were distributed throughout the lake on suspended material. Some results suggest that lateral mixing of contaminants in the St. Clair River results in transboundary pollution. Evidence of sporadic loadings of PCB was found. Inter-contaminant ratios were fairly consistent throughout the St. Clair-Detroit system indicating eventual transport of industrial contaminants from the St. Clair River to Lake Erie.

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