scholarly journals High spatial resolution analysis of the distribution of sulfate reduction and sulfide oxidation in hypoxic sediment in a eutrophic estuary

2016 ◽  
Vol 75 (2) ◽  
pp. 418-426
Author(s):  
Rathnayake M. L. D. Rathnayake ◽  
Shogo Sugahara ◽  
Hideaki Maki ◽  
Gen Kanaya ◽  
Yasushi Seike ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Spatial Resolution ◽  
Sediment Cores ◽  
Sulfide Oxidation ◽  
Sulfur Cycle ◽  
Sediment Surface ◽  
Concentration Profiles ◽  
Overlying Water ◽  
Global Environmental Issue ◽  
H2s Production

Bottom hypoxia and consequential hydrogen sulfide (H2S) release from sediment in eutrophic estuaries is a major global environmental issue. We investigated dissolved oxygen, pH and H2S concentration profiles with microsensors and by sectioning sediment cores followed by colorimetric analysis. The results of these analyses were then compared with the physicochemical properties of the bottom water and sediment samples to determine their relationships with H2S production in sediment. High organic matter and fine particle composition of the sediment reduced the oxidation-reduction potential, stimulating H2S production. Use of a microsensor enabled measurement of H2S concentration profiles with submillimetre resolution, whereas the conventional sediment-sectioning method gave H2S measurements with a spatial resolution of 10 mm. Furthermore, microsensor measurements revealed H2S consumption occurring at the sediment surface in both the microbial mat and the sediment anoxic layer, which were not observed with sectioning. This H2S consumption prevented H2S release into the overlying water. However, the microsensor measurements had the potential to underestimate H2S concentrations. We propose that a combination of several techniques to measure microbial activity and determine its relationships with physicochemical properties of the sediment is essential to understanding the sulfur cycle under hypoxic conditions in eutrophic sediments.

Oxygen concentration profiles and exchange in sediment cores with circulated overlying water

1989 ◽  
Vol 21 (3) ◽  
pp. 401-409 ◽  
Author(s):  
JEAN-PIERRE R. A. SWEERTS ◽  
VINCE ST LOUIS ◽  
THOMAS E. CAPPENBERG
Keyword(s):  
Oxygen Concentration ◽  
Sediment Cores ◽  
Concentration Profiles ◽  
Overlying Water

Molecular diffusive fluxes of oxygen in sediments of Port Phillip Bay in south-eastern Australia

1999 ◽  
Vol 50 (6) ◽  
pp. 557 ◽  
Author(s):  
Christopher M. Burke
Keyword(s):  
Sediment Cores ◽  
Sediment Surface ◽  
Overlying Water ◽  
South Eastern ◽  
Eastern Australia ◽  
Oxygen Cycling ◽  
Diffusive Fluxes ◽  
High Degree ◽  
South Eastern Australia

Port Phillip Bay is a large, shallow, semi-enclosed bay in south-eastern Australia. Micro- electrodes were used to measure profiles of oxygen concentration in sediment cores taken from nine sites in the bay in January and February 1994. The effects of sediment surface topography, flow rate of the overlying water and irradiance on the distribution of oxygen in the sediments, and on the molecular diffusive fluxes of oxygen, were determined. Oxygen typically penetrated ≤3 mm into the sediment. Deeper penetration occurred when oxygen was photosynthetically produced in situ. In most cores the sediments consumed oxygen. Molecular diffusive fluxes of oxygen, determined from the gradient of oxygen in the DBL, were compared with fluxes modelled from the sediment gradient of oxygen. The modelled diffusive fluxes are considered to give better estimates of the diffusive fluxes in situ. Modelled fluxes ranged from 1.5 to 28.5 mmol O2 m–2 day–1, which was 43% (s.d. = 36%, n = 16) of the total flux at each site. Cores from two sites demonstrated efflux of oxygen, up to 71 mmol O2 m–2 day–1, as a result of photosynthesis in situ. The high degree of variability in oxygen fluxes within cores demonstrates the dynamism of oxygen cycling in these sediments.

Exchange of trace elements at the sediment-water interface during early diagenesis processes

1995 ◽  
Vol 46 (1) ◽  
pp. 19 ◽  
Author(s):  
W Petersen ◽  
K Wallman ◽  
L Pinglin ◽  
F Schroeder ◽  
HD Knauth
Keyword(s):  
Trace Elements ◽  
Sediment Cores ◽  
Early Diagenesis ◽  
Water Phase ◽  
Laboratory Simulation ◽  
Sediment Surface ◽  
Water Interface ◽  
Large Area ◽  
Overlying Water ◽  
River Elbe

The exchange processes at the sediment-water interface can significantly influence the transport of trace contaminants in a river. In order to investigate the importance of these processes in the tidal part of the River Elbe, a laboratory 'simulation' apparatus (LABOSI) was used that allows the incubation of undisturbed sediment cores with a relatively large area (1700 cm²) in a closed system under defined conditions (temperature, pH, pE, etc.). Together with measured depth profiles of the pore-water and the solids of the incubated cores before and after the experiment, this method allows all relevant processes to be investigated in all three phases (sediment, overlying water, gas) simultaneously. Under oxic conditions, a flux of heavy metals (Cu, Cd , Zn) into the water phase was observed as a result of the mineralization of organic matter in the thin oxic layer of the sediment (thickness about 3 mm) as well as a flux of manganese caused by diffusion from deeper anoxic layers. Up to 40% of Cd, Zn and Ni and 15% of Zn deposited in the sediment by settling of contaminated suspended particulate matter can be remobilized from the sediment surface by the processes of early diagenesis. Within 14 days, an enrichment of arsenic in the sediment surface caused by diffusion from deeper anoxic layers could be detected. Under anoxic conditions and when the other electron acceptors were consumed, Fe(II) was released and accompanied by a strong remobilization of As, Co and Cr and an accelerated release of Mn(II). This release was soon stopped when the water phase became oxic again, and the trace elements were removed from the water phase by co-precipitation andlor adsorption on the freshly formed hydrous ferric oxides.

scholarly journals Sulfur Biogeochemical Cycle of Marine Sediments

2021 ◽  
pp. 145-307
Author(s):  
Bo Barker Jørgensen
Keyword(s):  
Organic Matter ◽  
Microbial Communities ◽  
Sulfate Reduction ◽  
Marine Sediments ◽  
Diffusion Flux ◽  
Sulfide Oxidation ◽  
Sulfur Cycle ◽  
Sediment Surface ◽  
Additional Tool ◽  
Microbiological Methods

Complex interactions between microbial communities and geochemical processes drive the major element cycles and control the function of marine sediments as a dynamic reservoir of organic matter. Sulfate reduction is globally the dominant pathway of anaerobic mineralisation and is the main source of sulfide. The effective re-oxidation of this sulfide at the direct or indirect expense of oxygen is a prerequisite for aerobic life on our planet. Although largely hidden beneath the oxic sediment surface, the sulfur cycle is therefore critical for Earth’s redox state. This Geochemical Perspectives begins with a brief primer on the sulfur cycle of marine sediments and a description of my own scientific journey through nearly fifty years of studies of sulfur geochemistry and microbiology. Among the main objectives of these studies were to quantify the main processes of the sulfur cycle and to identify the microbial communities behind them. Radiotracers in combination with chemical analyses have thereby been used extensively for laboratory experiments, supported by diverse molecular microbiological methods. The following sections discuss the main processes of sulfate reduction, sulfide oxidation and disproportionation of the inorganic sulfur intermediates, especially of elemental sulfur and thiosulfate. The experimental approaches used enable the analysis of how environmental factors such as substrate concentration or temperature affect process rates and how concurrent processes of sulfate reduction and sulfide oxidation drive a cryptic sulfur cycle. The chemical energy of sulfide is used by chemolithotrophic bacteria, including fascinating communities of big sulfur bacteria and cable bacteria, and supports their dark CO2 fixation, which produces new microbial biomass. During the burial and aging of marine sediments, the predominant mineralisation processes change through a cascade of redox reactions, and the rate of organic matter degradation drops continuously over many orders of magnitude. The main pathways of anaerobic mineralisation and the age control of the organic matter turnover are discussed. In the deep methanic zone, only a few percent of the entire degradation process remains, which provides a small boost of substrate for sulfate reduction through the process of anaerobic methane oxidation. The stable isotopes of sulfur provide an additional tool to understand these diagenetic processes, whereby the combination of microbial isotope fractionation and open system diagenesis generate a differential diffusion flux of the isotopes. In relation to the organic carbon cycle of the seabed and the contribution of methane, the paper discusses the global sulfur budget and the role of sulfate reduction for organic matter mineralisation in different depth regions of the ocean – from coast to deep sea. The published estimates of these parameters are evaluated and compared. Finally, the paper looks at future perspectives with respect to gaps in our current understanding and the need for further studies.

Substrate Uptake by Uncultured Bacteria from the Genus Achromatium Determined by Microautoradiography

1999 ◽  
Vol 65 (11) ◽  
pp. 5100-5106 ◽  
Author(s):  
N. D. Gray ◽  
R. Howarth ◽  
R. W. Pickup ◽  
J. Gwyn Jones ◽  
I. M. Head
Keyword(s):  
Protein Hydrolysate ◽  
Sediment Cores ◽  
Sulfide Oxidation ◽  
Sodium Molybdate ◽  
Organic Substrate ◽  
Sulfur Cycle ◽  
Substrate Uptake ◽  
Physiological Diversity ◽  
Uncultured Bacteria ◽  
Natural Communities

ABSTRACT Microautoradiography was used to investigate substrate uptake by natural communities of uncultured bacteria from the genusAchromatium. Studies of the uptake of14C-labelled substrates demonstrated thatAchromatium cells from freshwater sediments were able to assimilate 14C from bicarbonate, acetate, and protein hydrolysate; however, 14C-labelled glucose was not assimilated. The pattern of substrate uptake by Achromatiumspp. was therefore similar to those of a number of other freshwater and marine sulfur-oxidizing bacteria. Different patterns of radiolabelled bicarbonate uptake were noted for Achromatium communities from different geographical locations and indicated that one community (Rydal Water) possessed autotrophic potential, while the other (Hell Kettles) did not. Furthermore, the patterns of organic substrate uptake within a single population suggested that physiological diversity existed in natural communities of Achromatium. These observations are consistent with and may relate to the phylogenetic diversity observed in Achromatium communities. Incubation of Achromatium-bearing sediment cores from Rydal Water with35S-labelled sulfate in the presence and absence of sodium molybdate demonstrated that this bacterial population was capable of oxidizing sulfide to intracellular elemental sulfur. This finding supported the role of Achromatium in the oxidative component of a tightly coupled sulfur cycle in Rydal Water sediment. The oxidation of sulfide to sulfur and ultimately to sulfate byAchromatium cells from Rydal Water sediment is consistent with an ability to conserve energy from sulfide oxidation.

scholarly journals Cryptic role of tetrathionate in the sulfur cycle: A study from Arabian Sea sediments

2019 ◽  
Author(s):  
Subhrangshu Mandal ◽  
Sabyasachi Bhattacharya ◽  
Chayan Roy ◽  
Moidu Jameela Rameez ◽  
Jagannath Sarkar ◽  
...  
Keyword(s):  
Arabian Sea ◽  
Sediment Cores ◽  
Sulfur Cycle ◽  
Sediment Surface ◽  
Growth Media ◽  
Metagenome Analysis ◽  
Geochemical Analyses

Abstract. To explore the potential role of tetrathionate in the sulfur cycle of marine sediments, population ecology of microorganisms capable of metabolizing this polythionate was revealed at 15–30 cm resolution along two, ~ 3-m-long, cores collected from 530 and 580 meters below the sea level, off India's west coast, within the oxygen minimum zone (OMZ) of the Arabian Sea. Metagenome analysis along the two sediment-cores revealed widespread occurrence of genes involved in microbial formation, oxidation, and reduction of tetrathionate; high diversity and relative-abundance was also detected for bacteria that are known to render these metabolisms in vitro. Results of slurry-incubation of the sediment-samples in thiosulfate- or tetrathionate-containing microbial growth media, data obtained via pure-culture isolation, and finally metatranscriptome analyses, corroborated the in situ functionality of tetrathionate-forming, oxidizing, and reducing microorganisms. Geochemical analyses revealed the presence of up to 11.1 µM thiosulfate along the two cores, except a few sample-sites near the sediment-surface. Thiosulfate oxidation by chemolithotrophic bacteria prevalent in situ is the apparent source of tetrathionate in this ecosystem. However, potential abiotic origin of the polythionate can neither be ruled out nor confirmed from the geochemical information currently available for this territory. Tetrathionate, in turn, can be either oxidized to sulfate (via oxidation by the chemolithotrophs present) or reduced back to thiosulfate (via respiration by native bacteria). Up to 2.01 mM sulfide present in the sediment-cores may also reduce tetrathionate abiotically to thiosulfate and elemental sulfur. As tetrathionate was not detected in situ, high microbiological and geochemical reactivity of this polythionate was hypothesized to be instrumental in its cryptic status as a central sulfur cycle intermediate.

Pigment Preservation in Lake Sediments: A Comparison of Sedimentary Environments in Trout Lake, Wisconsin

1991 ◽  
Vol 48 (3) ◽  
pp. 472-486 ◽  
Author(s):  
James P. Hurley ◽  
David E. Armstrong
Keyword(s):  
Accumulation Rate ◽  
Sediment Cores ◽  
Sediment Accumulation ◽  
Sediment Surface ◽  
Water Interface ◽  
Sedimentary Pigments ◽  
Sedimentary Environments ◽  
Trout Lake ◽  
Secondary Carotenoids ◽  
Β Carotene

Fluxes and concentrations of a phorbins and major algal carotenoids were quantified in sediment trap material and sediment cores from two basins of Trout Lake, Wisconsin (TrDH and TrAB). The basins were chosen to contrast the influence of oxygen content at the sediment–water interface (TrDH, oxic and TrAB, reducing), sediment accumulation rate, and focusing. Pigment diagenesis occurred in both basins, but transformations and destruction were more extensive in TrDH. Although untransformed chlorophyll a was the major phorbin deposited at the sediment surface of both basins (51–64 mol%), pigment destruction, coupled with transition to pheophytin, accounted for substantial losses, especially in oxic TrDH sediments. Fucoxanthin, peridinin, and diadinoxanthin, despite representing > 70% of the deposited carotenoid flux, were substantially degraded or transformed in both basins. However, preservation was relatively high for secondary carotenoids, such as diatoxanthin and β-carotene, and for a major cryptomonad pigment, alloxanthin. Residual profiles in sediments show that pigment sedimentation from the epilimnion and accumulation in the permanent sediments are not directly related and that diagenesis must be considered in interpreting sedimentary pigments.

scholarly journals Behaviour of Metal(loid)s at the Sediment-Water Interface in an Aquaculture Lagoon Environment (Grado Lagoon, Northern Adriatic Sea, Italy)

2021 ◽  
Vol 11 (5) ◽  
pp. 2350
Author(s):  
Elisa Petranich ◽  
Matteo Crosera ◽  
Elena Pavoni ◽  
Jadran Faganeli ◽  
Stefano Covelli
Keyword(s):  
Sediment Cores ◽  
Fish Farm ◽  
Trophic Chain ◽  
Water Interface ◽  
Northern Adriatic Sea ◽  
Overlying Water ◽  
Northern Adriatic ◽  
In Situ Experiments ◽  
Diffusive Fluxes ◽  
Lagoon Environment

The cycling of metal(loid)s at the sediment–water interface (SWI) was evaluated at two selected sites (VN1 and VN3) in an active fish farm in the Grado Lagoon (Northern Adriatic, Italy). In situ experiments using a transparent benthic chamber and the collection of short sediment cores were performed, to investigate the behavior of metal(loid)s in the solid (sediments) and dissolved (porewaters) phases. Total and labile concentration of metal(loid)s were also determined in sediments, to quantify their potential mobility. Comparable total concentrations were found at both sites, excluding As, Mn, Pb and V, which were higher at VN3. Metal(loid) porewater profiles showed a diagenetic sequence and a close dependence with redox (suboxic/anoxic) conditions in the surface sediments. Positive diffusive fluxes along with benthic fluxes, particularly at the more oxic site, VN1, were found for almost all metal(loid)s, indicating their tendency to migrate towards the overlying water column. Despite sediments at two sites exhibiting high total metal(loid) concentrations and moderate effluxes at the SWI, the results suggest that they are hardly remobilized from the sediments. Recycling of metal(loid)s from the SWI would not constitute a threat for the aquatic trophic chain in the fish farm.

scholarly journals Oxygenation of anoxic sediments triggers hatching of zooplankton eggs

2015 ◽  
Vol 282 (1817) ◽  
pp. 20152025 ◽  
Author(s):  
Elias Broman ◽  
Martin Brüsin ◽  
Mark Dopson ◽  
Samuel Hylander
Keyword(s):  
Sediment Surface ◽  
Substantial Part ◽  
System Modelling ◽  
Anoxic Sediments ◽  
Overlying Water ◽  
Pelagic Copepod ◽  
Coastal Marine ◽  
Copepod Population ◽  
Benthic Pelagic Coupling ◽  
Dormant Eggs

Many coastal marine systems have extensive areas with anoxic sediments and it is not well known how these conditions affect the benthic–pelagic coupling. Zooplankton lay their eggs in the pelagic zone, and some sink and lie dormant in the sediment, before hatched zooplankton return to the water column. In this study, we investigated how oxygenation of long-term anoxic sediments affects the hatching frequency of dormant zooplankton eggs. Anoxic sediments from the brackish Baltic Sea were sampled and incubated for 26 days with constant aeration whereby, the sediment surface and the overlying water were turned oxic. Newly hatched rotifers and copepod nauplii (juveniles) were observed after 5 and 8 days, respectively. Approximately 1.5 × 10 5 nauplii m −2 emerged from sediment turned oxic compared with 0.02 × 10 5 m −2 from controls maintained anoxic. This study demonstrated that re-oxygenation of anoxic sediments activated a large pool of buried zooplankton eggs, strengthening the benthic–pelagic coupling of the system. Modelling of the studied anoxic zone suggested that a substantial part of the pelagic copepod population can derive from hatching of dormant eggs. We suggest that this process should be included in future studies to understand population dynamics and carbon flows in marine pelagic systems.

scholarly journals A new device to mount portable energy-dispersive X-ray fluorescence spectrometers (p-ED-XRF) for semi-continuous analyses of split (sediment) cores and solid samples

2017 ◽  
Vol 6 (1) ◽  
pp. 93-101 ◽  
Author(s):  
Philipp Hoelzmann ◽  
Torsten Klein ◽  
Frank Kutz ◽  
Brigitta Schütt
Keyword(s):  
Spatial Resolution ◽  
Atlantic Coast ◽  
Sediment Cores ◽  
Ccd Camera ◽  
Energy Dispersive ◽  
Solid Samples ◽  
Industrial Property ◽  
X Ray ◽  
New Device ◽  
Sample Chamber

Abstract. Portable energy-dispersive X-ray fluorescence spectrometers (p-ED-XRF) have become increasingly popular in sedimentary laboratories to quantify the chemical composition of a range of materials such as sediments, soils, solid samples, and artefacts. Here, we introduce a low-cost, clearly arranged unit that functions as a sample chamber (German industrial property rights no. 20 2014 106 048.0) for p-ED-XRF devices to facilitate economic, non-destructive, fast, and semi-continuous analysis of (sediment) cores or other solid samples. The spatial resolution of the measurements is limited to the specifications of the applied p-ED-XRF device – in our case a Thermo Scientific Niton XL3t p-ED-XRF spectrometer with a maximum spatial resolution of 0.3 cm and equipped with a charge-coupled device (CCD) camera to document the measurement spot. We demonstrate the strength of combining p-ED-XRF analyses with this new sample chamber to identify Holocene facies changes (e.g. marine vs. terrestrial sedimentary facies) using a sediment core from an estuarine environment in the context of a geoarchaeological investigation at the Atlantic coast of southern Spain.

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