COMPARISON OF THE IMPROVEMENT EFFECT OF VARIOUS SAND CAPPING MATERIALS ON THE BOTTOM WATER OXYGEN CONCENTRATION

Abstract. Rose Bengal stained foraminiferal assemblages were analysed along a five-station bathymetric transect across the core and the lower part of the oxygen minimum zone (OMZ) on the Indian margin of the Arabian Sea. Sediment cores were collected using the manned submersible Shinkai 6500 during RV Yokosuka cruise YK08-11 in the post-monsoon season (October 2008) at water depths ranging from 535 to 2000 m, along a gradient from almost anoxic to well-oxygenated (0.3 to 108 μM) bottom waters. Stained foraminiferal densities were very high in the OMZ core (535 m) and decreased with depth. The faunas were dominated (40–80%) by non-calcareous taxa at all stations. These were mainly species of Reophax and Lagenammina but also included delicate monothalamous taxa (organic-walled "allogromiids", agglutinated saccamminids, psammosphaerids and tubular forms). These new data from the Indian margin are compared to previous studies from the Murray Ridge, the Pakistan margin and the Oman margin. The fact that similar species were found at sites with comparable bottom-water oxygen concentrations but with very different surface water productivity suggests that, within the strongly developed Arabian Sea OMZ, bottom-water oxygen concentration, and not the organic flux to the sea floor, is the main factor controlling the species composition of the foraminiferal communities. Several foraminiferal species (e.g. Praeglobobulimina sp. 1, Ammodiscus sp. 1, Bolivina aff. dilatata) were confined to the core of the OMZ and are presently known only from the Arabian Sea. Because of their association with extremely low-oxygen concentration, these species may prove to be good indicators of past OMZ variability in the Arabian Sea.

Download Full-text

Effects of near-bottom water oxygen concentration on biogeochemical cycling of C, N and S in sediments of the Gulf of Gdansk (southern Baltic)

Continental Shelf Research ◽

10.1016/j.csr.2016.02.001 ◽

2016 ◽

Vol 117 ◽

pp. 30-42 ◽

Cited By ~ 12

Author(s):

Katarzyna Lukawska-Matuszewska ◽

Joanna Kielczewska

Keyword(s):

Oxygen Concentration ◽

Bottom Water ◽

Biogeochemical Cycling ◽

Gulf Of Gdańsk ◽

Water Oxygen ◽

Gulf Of Gdansk ◽

Southern Baltic

Download Full-text

Quantitative estimation of surface ocean productivity and bottom water oxygen concentration using benthic foraminifera

Paleoceanography ◽

10.1029/94pa01624 ◽

1994 ◽

Vol 9 (5) ◽

pp. 723-737 ◽

Cited By ~ 76

Author(s):

Paul Loubere

Keyword(s):

Oxygen Concentration ◽

Benthic Foraminifera ◽

Bottom Water ◽

Quantitative Estimation ◽

Surface Ocean ◽

Water Oxygen ◽

Ocean Productivity

Download Full-text

Coastal hypoxia and sediment biogeochemistry

Biogeosciences ◽

10.5194/bg-6-1273-2009 ◽

2009 ◽

Vol 6 (7) ◽

pp. 1273-1293 ◽

Cited By ~ 339

Author(s):

J. J. Middelburg ◽

L. A. Levin

Keyword(s):

Organic Matter ◽

Bottom Water ◽

Water Exchange ◽

Transport Processes ◽

Ecosystem Dynamics ◽

Ecosystem Functions ◽

Oxygen Levels ◽

Concise Review ◽

Water Oxygen ◽

Sediment Biogeochemistry

Abstract. The intensity, duration and frequency of coastal hypoxia (oxygen concentration <63 μM) are increasing due to human alteration of coastal ecosystems and changes in oceanographic conditions due to global warming. Here we provide a concise review of the consequences of coastal hypoxia for sediment biogeochemistry. Changes in bottom-water oxygen levels have consequences for early diagenetic pathways (more anaerobic at expense of aerobic pathways), the efficiency of re-oxidation of reduced metabolites and the nature, direction and magnitude of sediment-water exchange fluxes. Hypoxia may also lead to more organic matter accumulation and burial and the organic matter eventually buried is also of higher quality, i.e. less degraded. Bottom-water oxygen levels also affect the organisms involved in organic matter processing with the contribution of metazoans decreasing as oxygen levels drop. Hypoxia has a significant effect on benthic animals with the consequences that ecosystem functions related to macrofauna such as bio-irrigation and bioturbation are significantly affected by hypoxia as well. Since many microbes and microbial-mediated biogeochemical processes depend on animal-induced transport processes (e.g. re-oxidation of particulate reduced sulphur and denitrification), there are indirect hypoxia effects on biogeochemistry via the benthos. Severe long-lasting hypoxia and anoxia may result in the accumulation of reduced compounds in sediments and elimination of macrobenthic communities with the consequences that biogeochemical properties during trajectories of decreasing and increasing oxygen may be different (hysteresis) with consequences for coastal ecosystem dynamics.

Download Full-text

Oxygen depletion during sapropel deposition: Reassessing redox proxies for reconstructing surface and bottom water oxygen conditions

10.7185/gold2021.4601 ◽

2021 ◽

Author(s):

Ricardo Monedero-Contreras ◽

Francisca Martinez-Ruiz ◽

Francisco J. Rodríguez-Tovar ◽

David Gallego-Torres ◽

Gert J. de Lange

Keyword(s):

Bottom Water ◽

Oxygen Depletion ◽

Water Oxygen ◽

Oxygen Conditions

Download Full-text

Foraminiferal response to Albian relative sea-level changes in northwestern and central Alberta, Canada

Canadian Journal of Earth Sciences ◽

10.1139/e99-079 ◽

1999 ◽

Vol 36 (10) ◽

pp. 1617-1643 ◽

Cited By ~ 6

Author(s):

Rebecca A Stritch ◽

Claudia J Schröder-Adams

Keyword(s):

Sea Level ◽

Bottom Water ◽

Gradual Increase ◽

Western Canada ◽

Sea Level Changes ◽

Relative Sea Level ◽

Sea Level Fluctuations ◽

Faunal Assemblages ◽

Water Oxygen ◽

Southern Alberta

Albian foraminiferal assemblages from three wells in northwestern (Imperial Spirit River No. 1, 12-20-78-6W6), central (AngloHome C&E Fort Augustus No. 1, 7-29-55-21W4), and southern Alberta (Amoco B1 Youngstown, 6-34-30-8W4) provide the basis to track a fluctuating sea-level history in western Canada. Two global second-order marine cycles (Kiowa - Skull Creek and Greenhorn) were punctuated by higher frequency relative sea-level cycles expressed during the time of the Moosebar-Clearwater, Hulcross, Joli Fou, and Mowry seas. A total of 34 genera and 93 subgeneric taxa are recognized in these Albian-age strata. Foraminiferal abundance and species diversity of the latest Albian Mowry Sea were higher than in the early to middle Albian Moosebar-Clearwater and Hulcross seas. The two earliest paleo-seas were shallow embayments of the Boreal Sea, and relative sea-level fluctuations caused variable marine to brackish conditions expressed in a variety of faunal assemblages. Towards the late Albian, relative sea level rose, deepening the basin and establishing increased marine conditions and more favourable habitats for foraminifera. In the deeper Joli Fou Seaway and Mowry Sea, however, reduced bottom water oxygen through stratification or stagnant circulation caused times of diminished benthic faunas. The Bluesky Formation in northwestern Alberta contains the initial transgression of the early Albian Moosebar-Clearwater Sea and is marked by a sudden faunal increase. In contrast, transgression by the late late Albian Mowry Sea was associated with a gradual increase of foraminiferal faunas. Numerous agglutinated species range throughout the entire Albian, absent only at times of basin shallowing. However, each major marine incursion throughout the Albian introduced new taxa.

Download Full-text