scholarly journals Multiple Ecological Parameters Affect Living Benthic Foraminifera in the River-Influenced West-Central Bay of Bengal

2021 ◽  
Vol 8 ◽  
Author(s):  
Thejasino Suokhrie ◽  
Rajeev Saraswat ◽  
Rajiv Nigam
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Dissolved Oxygen ◽  
Bay Of Bengal ◽  
Benthic Foraminifera ◽  
Coarse Fraction ◽  
Godavari River ◽  
West Central ◽  
Ecological Parameters ◽  
Chemical Conditions

The huge riverine influx and associated processes decrease the ambient salinity, stratify the water column, modulate the oxygen-deficient zone, and are also responsible for the recent acidification in the Bay of Bengal. Here, we have studied the effect of these riverine influx-dominated ecological parameters on living benthic foraminifera in the west-central Bay of Bengal. We report that the pH below 7.6 in front of the Krishna river, reduces the diversity and the richness of living benthic foraminifera on the adjacent shelf and the slope. A similar decreased diversity and richness is also observed in front of the Godavari River. We delineate three prominent assemblages, representing different depth zones with associated distinct physico-chemical conditions. The shallow water assemblage (∼27–100 m) is represented by Nonionella labradorica, Hanzawaia nipponica, Brizalina dilatata, Ammonia tepida, and Nonionella limbato-striata. These species are adapted to relatively warmer temperatures and more oxygenated waters. The deepwater assemblage (∼1,940–2,494 m) includes Bulimina cf. delreyensis, Bulimina marginata, Hormosinella guttifera, Cassidulina laevigata, and Gyroidinoides subzelandica and can tolerate a relatively colder temperature. The intermediate-depth assemblage (∼145–1,500 m) dominated by Eubuliminella exilis, Bolivinellina earlandi, Fursenkoina spinosa, Bolivinellina lucidopunctata, Globobulimina globosa, Fursenkoina spinosa, Eubuliminella cassandrae, Uvigerina peregrina, Rotaliatinopsis semiinvoluta, and Cassidulina laevigata, represents oxygen-deficient and organic carbon-rich environment. Besides the pH, temperature, dissolved oxygen and organic matter, we also report a strong influence of bathymetry, coarse fraction (CF) and the type of organic matter on a few living benthic foraminifera. The ecological preferences of 40 such dominant living benthic foraminifera, each representing a specific environment, have also been reported for site-specific proxy. We conclude that although the huge riverine influx affects living benthic foraminifera on the shelf, the dissolved oxygen and organic carbon mostly control benthic foraminiferal distribution in the deeper west-central Bay of Bengal.

scholarly journals Oxygen uptake during mineralization of humic substances from Infernão Lagoon (São Paulo, Brazil)

2004 ◽  
Vol 64 (3b) ◽  
pp. 583-590 ◽  
Author(s):  
M. B. Cunha-Santino ◽  
I. Bianchini JR.
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Oxygen Uptake ◽  
Dissolved Oxygen ◽  
Humic Substances ◽  
Aquatic Macrophyte ◽  
Uptake Coefficient ◽  
First Order ◽  
First Order Kinetics ◽  
Different Sources

Assays were carried out to evaluate the dissolved oxygen uptake resulting from mineralization of humic substances (fulvic acid (FA) and humic acid (HA)) from different sources: sediment, dissolved organic matter (DOM) of 120-day decomposed aquatic macrophyte (Scirpus cubensis and Cabomba piauhyensis), and lagoon DOM. The experiments were also aimed at estimating the oxygen uptake coefficient of the mineralization. About 20-30 mg of substrate were added to 1.1 liters of water from Infernão Lagoon (21º33' to 21º37'S; 47º45' to 47º51'W). The solutions were aerated and the dissolved oxygen (DO) was monitored during 40 days. Dissolved organic carbon (DOC) and particulate organic carbon (POC) were estimated after 80 days of the experiment. Anaerobic processes were avoided by aerating the solutions. The results were fitted to a first-order kinetics model, from which the uptake of oxygen parameters was obtained. Oxygen consumption (OC) ranged from 4.24 mg L-1 (HA - S. cubensis) to 33.76 mg L-1 (FA - sediment). The highest deoxygenation coefficient (kD) was observed during mineralization of FA - DOM (0.299 day-1), followed in decreasing order by FA - S. cubensis, HA - sediment, HA - S. cubensis, FA - sediment, and FA - C. piauhyensis (0.282; 0.255; 0.178; 0.130, and 0.123 day-1, respectively). The carbon analyses indicated that the FA and HA samples at the end of the experiment presented a decay that varied from 15.23% to 42.35% and that the FA and HA conversions into POC were relatively low (from 0.76% to 3.94%).

scholarly journals Presentation, calibration and validation of the low-order, DCESS Earth System Model (Version 1)

2008 ◽  
Vol 1 (1) ◽  
pp. 17-51 ◽  
Author(s):  
G. Shaffer ◽  
S. Malskær Olsen ◽  
J. O. Pepke Pedersen
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Dissolved Oxygen ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
System Model ◽  
Earth System ◽  
Weathering Rates ◽  
Ocean Sediment ◽  
System Data

Abstract. A new, low-order Earth System Model is described, calibrated and tested against Earth system data. The model features modules for the atmosphere, ocean, ocean sediment, land biosphere and lithosphere and has been designed to simulate global change on time scales of years to millions of years. The atmosphere module considers radiation balance, meridional transport of heat and water vapor between low-mid latitude and high latitude zones, heat and gas exchange with the ocean and sea ice and snow cover. Gases considered are carbon dioxide and methane for all three carbon isotopes, nitrous oxide and oxygen. The ocean module has 100 m vertical resolution, carbonate chemistry and prescribed circulation and mixing. Ocean biogeochemical tracers are phosphate, dissolved oxygen, dissolved inorganic carbon for all three carbon isotopes and alkalinity. Biogenic production of particulate organic matter in the ocean surface layer depends on phosphate availability but with lower efficiency in the high latitude zone, as determined by model fit to ocean data. The calcite to organic carbon rain ratio depends on surface layer temperature. The semi-analytical, ocean sediment module considers calcium carbonate dissolution and oxic and anoxic organic matter remineralisation. The sediment is composed of calcite, non-calcite mineral and reactive organic matter. Sediment porosity profiles are related to sediment composition and a bioturbated layer of 0.1 m thickness is assumed. A sediment segment is ascribed to each ocean layer and segment area stems from observed ocean depth distributions. Sediment burial is calculated from sedimentation velocities at the base of the bioturbated layer. Bioturbation rates and oxic and anoxic remineralisation rates depend on organic carbon rain rates and dissolved oxygen concentrations. The land biosphere module considers leaves, wood, litter and soil. Net primary production depends on atmospheric carbon dioxide concentration and remineralization rates in the litter and soil are related to mean atmospheric temperatures. Methane production is a small fraction of the soil remineralization. The lithosphere module considers outgassing, weathering of carbonate and silicate rocks and weathering of rocks containing old organic carbon and phosphorus. Weathering rates are related to mean atmospheric temperatures. A pre-industrial, steady state calibration to Earth system data is carried out. Ocean observations of temperature, carbon 14, phosphate, dissolved oxygen, dissolved inorganic carbon and alkalinity constrain air-sea exchange and ocean circulation, mixing and biogeochemical parameters. Observed calcite and organic carbon distributions and inventories in the ocean sediment help constrain sediment module parameters. Carbon isotopic data and carbonate vs. silicate weathering fractions are used to estimate initial lithosphere outgassing and rock weathering rates. Model performance is tested by simulating atmospheric greenhouse gas increases, global warming and model tracer evolution for the period 1765 to 2000, as forced by prescribed anthropogenic greenhouse gas inputs and other anthropogenic and natural forcing. Long term, transient model behavior is studied with a set of 100 000 year simulations, forced by a slow, 5000 Gt C input of CO2 to the atmosphere, and with a 1.5 million year simulation, forced by a doubling of lithosphere CO2 outgassing.

scholarly journals Organic-carbon-rich sediments: benthic foraminifera as bio-indicators of depositional environments

2019 ◽  
Vol 16 (21) ◽  
pp. 4183-4199 ◽  
Author(s):  
Elena Lo Giudice Cappelli ◽  
Jessica Louise Clarke ◽  
Craig Smeaton ◽  
Keith Davidson ◽  
William Edward Newns Austin
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Carbon Content ◽  
Benthic Foraminifera ◽  
Organic Content ◽  
Depositional Environments ◽  
Organic Carbon Content ◽  
Carbon Burial ◽  
Actual Change ◽  
Freshwater Inputs

Abstract. Fjords have been described as hotspots for carbon burial, potentially playing a key role within the carbon cycle as climate regulators over multiple timescales. Nevertheless, little is known about the long-term fate of the carbon that may become stored in fjordic sediments. One of the main reasons for this knowledge gap is that carbon arriving on the seafloor is prone to post-depositional degradation, posing a great challenge when trying to discriminate between an actual change in the carbon deposition rate and post-depositional carbon loss. In this study, we evaluate the use of modern benthic foraminifera as bio-indicators of organic carbon content in six voes (fjords) on the west coast of Shetland. Benthic foraminifera are known to be sensitive to changes in organic carbon content in the sediments, and changes in their assemblage composition therefore reflect synchronous variations in the quantity and quality of carbon reaching the seafloor. We identified four environments based on the relationship between benthic foraminiferal assemblages and organic carbon content in the sediments: (1) land-locked regions influenced by riverine and/or freshwater inputs of organic matter, namely the head of fjords with a restricted geomorphology; (2) stressed environments with a heavily stratified water column and sediments rich in organic matter of low nutritional value; (3) depositional environments with moderate organic content and mild or episodic current activity; and (4) marginal to coastal settings with low organic content, such as fjords with an unrestricted geomorphology. We conclude that foraminifera potentially provide a tool to disentangle primary organic carbon signals from post-depositional degradation and loss of organic carbon because of their environmental sensitivity and high preservation potential in the sedimentary record.

scholarly journals Presentation, calibration and validation of the low-order, DCESS Earth System Model

2008 ◽  
Vol 1 (1) ◽  
pp. 39-124
Author(s):  
G. Shaffer ◽  
S. Malskǽr Olsen ◽  
J. O. P. Pedersen
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Dissolved Oxygen ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
System Model ◽  
Earth System ◽  
Weathering Rates ◽  
Ocean Sediment ◽  
System Data

Abstract. A new, low-order Earth system model is described, calibrated and tested against Earth system data. The model features modules for the atmosphere, ocean, ocean sediment, land biosphere and lithosphere and has been designed to simulate global change on time scales of years to millions of years. The atmosphere module considers radiation balance, meridional transport of heat and water vapor between low-mid latitude and high latitude zones, heat and gas exchange with the ocean and sea ice and snow cover. Gases considered are carbon dioxide and methane for all three carbon isotopes, nitrous oxide and oxygen. The ocean module has 100 m vertical resolution, carbonate chemistry and prescribed circulation and mixing. Ocean biogeochemical tracers are phosphate, dissolved oxygen, dissolved inorganic carbon for all three carbon isotopes and alkalinity. Biogenic production of particulate organic matter in the ocean surface layer depends on phosphate availability but with lower efficiency in the high latitude zone, as determined by model fit to ocean data. The calcite to organic carbon rain ratio depends on surface layer temperature. The semi-analytical, ocean sediment module considers calcium carbonate dissolution and oxic and anoxic organic matter remineralisation. The sediment is composed of calcite, non-calcite mineral and reactive organic matter. Sediment porosity profiles are related to sediment composition and a bioturbated layer of 0.1 m thickness is assumed. A sediment segment is ascribed to each ocean layer and segment area stems from observed ocean depth distributions. Sediment burial is calculated from sedimentation velocities at the base of the bioturbated layer. Bioturbation rates and oxic and anoxic remineralisation rates depend on organic carbon rain rates and dissolved oxygen concentrations. The land biosphere module considers leaves, wood, litter and soil. Net primary production depends on atmospheric carbon dioxide concentration and remineralization rates in the litter and soil are related to mean atmospheric temperatures. Methane production is a small fraction of the soil remineralization. The lithosphere module considers outgassing, weathering of carbonate and silicate rocks and weathering of rocks containing old organic carbon and phosphorus. Weathering rates are related to mean atmospheric temperatures. A pre-industrial, steady state calibration to Earth system data is carried out. Ocean observations of temperature, carbon 14, phosphate, dissolved oxygen, dissolved inorganic carbon and alkalinity constrain air-sea exchange and ocean circulation, mixing and biogeochemical parameters. Observed calcite and organic carbon distributions and inventories in the ocean sediment help constrain sediment module parameters. Carbon isotopic data and carbonate vs silicate weathering fractions are used to estimate initial lithosphere outgassing and rock weathering rates. Model performance is tested by simulating atmospheric greenhouse gas increases, global warming and model tracer evolution for the period 1765 to 2000, as forced by prescribed anthropogenic greenhouse gas inputs and other anthropogenic and natural forcing. Long term, transient model behavior is studied with a set of 100 000 year simulations, forced by a slow, 5000 GtC input of CO2 to the atmosphere, and with a 1.5 million year simulation, forced by a doubling of lithosphere CO2 outgassing.

scholarly journals Reconciling drainage and receiving basin signatures of the Godavari River system

2018 ◽  
Vol 15 (11) ◽  
pp. 3357-3375 ◽  
Author(s):  
Muhammed Ojoshogu Usman ◽  
Frédérique Marie Sophie Anne Kirkels ◽  
Huub Michel Zwart ◽  
Sayak Basu ◽  
Camilo Ponton ◽  
...  
Keyword(s):  
Grain Size ◽  
Organic Carbon ◽  
Surface Area ◽  
Continental Margin ◽  
Bay Of Bengal ◽  
River Sediments ◽  
Mineral Surface ◽  
Godavari River ◽  
Mineral Surface Area ◽  
Godavari Basin

Abstract. The modern-day Godavari River transports large amounts of sediment (170 Tg per year) and terrestrial organic carbon (OCterr; 1.5 Tg per year) from peninsular India to the Bay of Bengal. The flux and nature of OCterr is considered to have varied in response to past climate and human forcing. In order to delineate the provenance and nature of organic matter (OM) exported by the fluvial system and establish links to sedimentary records accumulating on its adjacent continental margin, the stable and radiogenic isotopic composition of bulk OC, abundance and distribution of long-chain fatty acids (LCFAs), sedimentological properties (e.g. grain size, mineral surface area, etc.) of fluvial (riverbed and riverbank) sediments and soils from the Godavari basin were analysed and these characteristics were compared to those of a sediment core retrieved from the continental slope depocenter. Results show that river sediments from the upper catchment exhibit higher total organic carbon (TOC) contents than those from the lower part of the basin. The general relationship between TOC and sedimentological parameters (i.e. mineral surface area and grain size) of the sediments suggests that sediment mineralogy, largely driven by provenance, plays an important role in the stabilization of OM during transport along the river axis, and in the preservation of OM exported by the Godavari to the Bay of Bengal. The stable carbon isotopic (δ13C) characteristics of river sediments and soils indicate that the upper mainstream and its tributaries drain catchments exhibiting more 13C enriched carbon than the lower stream, resulting from the regional vegetation gradient and/or net balance between the upper (C4-dominated plants) and lower (C3-dominated plants) catchments. The radiocarbon contents of organic carbon (Δ14COC) in deep soils and eroding riverbanks suggests these are likely sources of “old” or pre-aged carbon to the Godavari River that increasingly dominates the late Holocene portion of the offshore sedimentary record. While changes in water flow and sediment transport resulting from recent dam construction have drastically impacted the flux, loci, and composition of OC exported from the modern Godavari basin, complicating reconciliation of modern-day river basin geochemistry with that recorded in continental margin sediments, such investigations provide important insights into climatic and anthropogenic controls on OC cycling and burial.

scholarly journals Reconciling drainage and receiving basin signatures of the Godavari River system

2018 ◽  
Author(s):  
Muhammed O. Usman ◽  
Frédérique M. S. A. Kirkels ◽  
Huub M. Zwart ◽  
Sayak Basu ◽  
Camilo Ponton ◽  
...  
Keyword(s):  
Grain Size ◽  
Organic Carbon ◽  
Surface Area ◽  
Continental Margin ◽  
Bay Of Bengal ◽  
River Sediments ◽  
River System ◽  
Peninsular India ◽  
Godavari River ◽  
Godavari Basin

Abstract. The modern-day Godavari River transports large amounts of sediment (170 Tg per year) and terrestrial organic carbon (OCterr; 1.5 Tg per year) from peninsular India to the Bay of Bengal. The flux and nature of OCterr is considered to have varied in response to past climate and human forcing. In order to delineate the provenance and nature of organic matter (OM) exported by the fluvial system and establish links to sedimentary records accumulating on its adjacent continental margin, the stable and radiogenic isotopic composition of bulk OC, abundance and distribution of long-chain fatty acids (LCFA), sedimentological properties (e.g. grain size, mineral surface area etc.) of fluvial (riverbed and riverbank) sediments and soils from the Godavari basin were analysed and these characteristics were compared to those of a sediment core retrieved from the continental slope depocenter. Results show that river sediments from the upper catchment exhibit higher total organic carbon (TOC) contents than those from the lower part of the basin. The general relationship between TOC and sedimentological parameters (i.e., mineral-specific surface area and grain size) of the sediments suggests that sediment mineralogy, largely driven by provenance, plays an important role in the stabilization of OM during transport along the river axis, and in preservation of OM exported by the Godavari to the Bay of Bengal. The stable carbon isotopic (δ13C) characteristics of river sediments and soils indicate that the upper mainstream and its tributaries drain catchments exhibiting more 13C enriched carbon than the lower stream resulting from the regional vegetation gradient and/or net balance between the upper (C4-dominated plants) and lower (C3-dominated plants) catchments. The radiocarbon contents of organic carbon (Δ14COC) in deep soils and eroding riverbanks suggests these are likely sources of “old” or pre-aged carbon to the Godavari River that increasingly dominates the late Holocene portion of the offshore sedimentary record. Reduced monsoonal rainfall and sediment transport impeded by recent dam constructions have drastically impacted the flux, loci and composition of OC exported from the modern Godavari basin, rendering it challenging to reconcile modern-day river geochemistry with that recorded in continental margin sediments.

Morphological variations of benthic foraminiferal tests in response to changes in ecological parameters: a review

1991 ◽  
Vol 65 (2) ◽  
pp. 175-185 ◽  
Author(s):  
E. Boltovskoy ◽  
D. B. Scott ◽  
F. S. Medioli
Keyword(s):  
Trace Elements ◽  
Dissolved Oxygen ◽  
Morphological Variation ◽  
Benthic Foraminifera ◽  
Recent Literature ◽  
Morphological Changes ◽  
Environmental Parameters ◽  
Environmental Fluctuation ◽  
Morphological Variations ◽  
Ecological Parameters

Some of the relatively recent literature correlating morphological variation in benthic foraminifera with environmental parameters such as temperature, salinity, carbonate solubility, depth, nutrition, substrate, dissolved oxygen, illumination, pollution, water motion, trace elements, and rapid environmental fluctuation is reviewed. It appears some variables (most notably depth) are recorded more frequently, which may affect some conclusions. Although each variable is treated separately, it appears that almost no variables act independently on test morphologies. In reviewing the literature, it becomes clear that there are many individual trends, especially with shell ornamentation, but few broad ones, and that it is almost impossible, with exception of some of the larger reef-dwelling, symbiont-bearing foraminifera, to predict how any species will react to various parameters. The broad trends concern thinning or thickening of carbonate tests with changing carbonate availability, temperature, and salinity. It appears that many observations of morphological changes within species may not be recorded in the literature, perhaps because authors did not recognize the importance of small details that would be of importance at a later time.

Earth’s Middle Ages: What Came after the GOE

2017 ◽  
Author(s):  
Donald Eugene Canfield
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Middle Ages ◽  
Atmospheric Oxygen ◽  
Iron Formation ◽  
Banded Iron Formation ◽  
Dissolved Iron ◽  
Great Oxidation Event ◽  
Low Levels ◽  
Substantial Rise

This chapter considers the aftermath of the great oxidation event (GOE). It suggests that there was a substantial rise in oxygen defining the GOE, which may, in turn have led to the Lomagundi isotope excursion, which was associated with high rates of organic matter burial and perhaps even higher concentrations of oxygen. This excursion was soon followed by a crash in oxygen to very low levels and a return to banded iron formation deposition. When the massive amounts of organic carbon buried during the excursion were brought into the weathering environment, they would have represented a huge oxygen sink, drawing down levels of atmospheric oxygen. There appeared to be a veritable seesaw in oxygen concentrations, apparently triggered initially by the GOE. The GOE did not produce enough oxygen to oxygenate the oceans. Dissolved iron was removed from the oceans not by reaction with oxygen but rather by reaction with sulfide. Thus, the deep oceans remained anoxic and became rich in sulfide, instead of becoming well oxygenated.

scholarly journals Impact of aquaculture on distribution of dissolved organic matter in coastal Jeju Island, Korea, based on absorption and fluorescence spectroscopy

2021 ◽  
Author(s):  
Jeonghyun Kim ◽  
Yeseul Kim ◽  
Sung Eun Park ◽  
Tae-Hoon Kim ◽  
Bong-Guk Kim ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Fluorescence Spectroscopy ◽  
Dissolved Organic Matter ◽  
Coastal Water ◽  
Coastal Region ◽  
Principal Component ◽  
Distribution Patterns ◽  
Organic Pollution ◽  
Jeju Island

AbstractIn Jeju Island, multiple land-based aquafarms were fully operational along most coastal region. However, the effect of effluent on distribution and behaviours of dissolved organic matter (DOM) in the coastal water are still unknown. To decipher characteristics of organic pollution, we compared physicochemical parameters with spectral optical properties near the coastal aquafarms in Jeju Island. Absorption spectra were measured to calculate the absorption coefficient, spectral slope coefficient, and specific UV absorbance. Fluorescent DOM was analysed using fluorescence spectroscopy coupled with parallel factor analysis. Dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) were measured using high-temperature catalytic oxidation. The DOC concentration near the discharge outlet was twice higher than that in natural groundwater, and the TDN concentration exponentially increased close to the outlet. These distribution patterns indicate that aquafarms are a significant source of DOM. Herein, principal component analysis was applied to categorise the DOM origins. There were two distinct groups, namely, aquaculture activity for TDN with humic-like and high molecular weights DOM (PC1: 48.1%) and natural biological activity in the coastal water for DOC enrichment and protein-like DOM (PC2: 18.8%). We conclude that the aquafarms significantly discharge organic nitrogen pollutants and provoke in situ production of organic carbon. Furthermore, these findings indicate the potential of optical techniques for the efficient monitoring of anthropogenic organic pollutants from aquafarms worldwide.

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