Liter Of Sediment Research Articles

ESTIMATION OF METHANE FLOW FROM THE BOTTOM OF THE KARA SEA

During the expedition on the R/V “Akademik Mstislav Keldysh” (81st cruise) in 2020, extensive material was selected, representing columns of bottom sediments up to 6 meters deep in the Kara Sea. After lithological description of the columns, sediment samples were taken from different horizons for degassing of pore gases. The extracted gas samples were analyzed for the content of the main gases – methane (CH4), carbon dioxide (CO2) and light hydrocarbons. The characteristic features of CH4 and CO2 content changes with depth of bottom sediment at station 6879 (Kara Sea shelf) were studied. A model of gas diffusion was constructed taking into account the biochemical reactions of methanogenesis and methane oxidation. The rate of methane formation can be estimated by the value J ≈ 3 × 10–10 μg sec–1 L–1 (per liter of sediment). The rate coefficient of methane consumption by microorganisms is K ≈ 0.5 × 10–10 sec–1. The methane flux from the bottom surface of the Kara Sea near station 6879 is q ≈ 3.47 × 10–2 μL m–1 year–1.

Estimation of Methane Flow from the Bottom of the Kara Sea

During the expedition of cruise 81 on R/V Akademik Mstislav Keldysh in 2020, extensive material, representing columns of bottom sediments up to 6 m deep in the Kara Sea, was selected. After the lithological description of the columns, sediment samples were taken from the different horizons for degassing of pore gases. The extracted gas samples were analyzed for the content of the main gases, such as methane (CH4), carbon dioxide (CO2), and light hydrocarbons. The characteristic features of changes in the CH4 and CO2 content with the depth of the bottom sediments at station 6879 (the Kara Sea shelf) were studied. A model of gas diffusion was constructed taking into account the biochemical reactions of methanogenesis and methane oxidation. The rate of methane formation can be estimated by the value J ≈ 3 × 10−10 μg s−1 L−1 (per liter of sediment). The coefficient of rate of methane consumption by microorganisms is K ≈ 0.5 × 10−10 s−1. The methane flow from the bottom surface of the Kara Sea near station 6879 is q ≈ 3.47 × 10−1 μL m−2 yr−1.

Food and Ornament: Use of Shellfish at Ifri Oudadane, a Holocene Settlement in NE Morocco

Recent excavations of Ifri Oudadane, a prehistoric rockshelter on the Mediterranean coast of NW Morocco, yielded a rich marine and terrestrial fauna. We present an analysis of the shellfish remains (exoskeleton-bearing aquatic invertebrates) from the 2011 trench, covering the Epipaleolithic and Early Neolithic levels. A total of 4,415 liters of sediment contained 8,749 specimens (MNI) of at least 40 species of shellfish: 12 bivalves, 24 gastropods, one tusk shell, barnacles, crabs, and sea urchins. The mean abundance of shellfish was 2 MNI per liter. Limpets (Patellidae), topshells (Trochidae), mussels (Mytilidae), and rockshells (Muricidae) formed 98% of the total mollusk fauna and were part of the diet; limpets prevailed in Epipaleolithic levels and topshells in Neolithic ones. Evidence was found for a systematic butchering of topshells (Phorcus turbinatus): the shells in Epipaleolithic levels were mostly smashed while topshells in Neolithic levels were usually topped in a uniform way. Seven species of mollusks showed traces of manipulation and were used as ornament or tools. Species used as food, such as limpets, topshells, and mussels, never show any indications of being used as ornament or tools, and the mollusks that were used as jewelry or tools were not part of the diet.

Deposit- and suspension-feeding sea cucumbers (Echinodermata) ingest plastic fragments

Weathering of plastic bottles, bags, fishing line, and other products discarded in the ocean causes tiny fragments to break off. These plastic fragments may accumulate biofilms, sink, and become mixed with sediment, where benthic invertebrates may encounter and ingest them. Here we show that four species of deposit-feeding and suspension-feeding sea cucumbers (Echinodermata, Holothuroidea) not only ingest small (0.25 mm < maximum dimension < 15 mm) nylon and polyvinyl chloride (PVC) fragments along with sediment, but also ingest significantly more plastic fragments than predicted given the ratio of plastic to sand grains in the sediment. During four-hour feeding trials, holothurians ingested between 2- and 20-fold more plastic per individual than expected for PVC fragments, and between 2- and 138-fold more for nylon line. In addition, two species ingested 4 mm diameter PVC pellets. The ecological relevance of plastic ingestion was assessed in the laboratory by counting and characterizing small plastic particles discovered in sediment samples from the same field sites where our holothurians were collected. Substantial numbers of plastic fragments (105 to 214 fragments per liter of sediment) were found in samples from three different locations along the east coast of the U.S.A. In addition, plastic collected from the sediment from two of our field sites was analyzed for polychlorinated biphenyls (PCBs). Plastic from one site tested positive for Aroclor 1254 at a concentration of 0.0106 μg g -1. While the negative effects of macroscopic marine plastic debris on a host of organisms are well documented, ingestion of small plastic debris by a wide range of benthic organisms, including both primary and secondary consumers, has received little attention. Given that plastics readily adsorb PCBs and other organic pollutants in marine environments, ingestion of plastic from sediment may provide a heretofore-undescribed pathway of exposure for benthic marine invertebrates.

A vacuum-operated pore-water extractor for estuarine and freshwater sediments

A vacuum-operated pore-water extractor for estuarine and freshwater sediments was developed and constructed from a fused-glass air stone attached with aquarium airline tubing to a 30 or 60 cc polypropylene syringe. Pore water is extracted by inserting the air stone into the sediment and creating a vacuum by retracting and bracing the syringe plunger. A hand-operated vacuum pump attached to a filtration flask was also evaluated as an alternative vacuum source. The volume and time to extract pore water varies with the number of devices and the sediment particle size. Extraction time is longer for fine sediments than for sandy sediments. Four liters of sediment generally yield between 500 and 1,500 mL of pore water. The sediment that surrounds and accumulates on the air stone acts as a filter, and, except for the first few milliliters, the collected pore water is clear. Because there is no exposure to air or avenue for escape, volatile compounds andin situ characteristics are retained in the extracted pore water.

Dimethyl sulfide metabolism in salt marsh sediments

Anoxic sediment slurries prepared from Spartina salt marsh soils contained dimethyl sulfide (DMS) at concentrations ranging from 1 to 10 μM. DMS was produced in slurries over the initial 1–24 h incubation. After the initial period of production, DMS decreased to undetectable levels and methane thiol (MSH) was produced. Inhibition of methanogenesis caused a 20% decrease in the rate of DMS consumption, while inhibition of sulfate reduction caused a 80% decrease in DMS consumption. When sulfate reduction and methanogenesis were simultaneously inhibited, DMS did not decrease. DMS contributed about 28% to the methane production rate, while DMS probably contributed only 1% or less to the sulfate reduction rate. Incubation of the sediment slurries under an atmosphere of air resulted in similar DMS consumption compared to anaerobic incubations, but MSH and CH4 were not evolved. Sediments from the marsh released significant quantities of DMS when treated with cold alkali, indicating that potentially significant sources of DMS existed in the sediments. Values of base-hydrolyzable DMS as high as 190 μmol per liter of sediment were observed near the sediment surface, and values always decreased with depth in the sediment. Simple flux experiments with small intact sediment cores, showed that DMS was emitted from the marsh surface when cores were injected with glutaraldehyde or molybdate and 2-bromoethanesulfonate (BES), but nit when cores were left uninhibited. These results showed that DMS was readily metabolized by microbes in marsh sediments and that this metabolism may be responsible for reducing the emission of DMS from the marsh surface.

Dimethyl sulfide metabolism in salt marsh sediments

Abstract Anoxic sediment slurries prepared from Spartina salt marsh soils contained dimethyl sulfide (DMS) at concentrations ranging from 1 to 10 μM. DMS was produced in slurries over the initial 1–24 h incubation. After the initial period of production, DMS decreased to undetectable levels and methane thiol (MSH) was produced. Inhibition of methanogenesis caused a 20% decrease in the rate of DMS consumption, while inhibition of sulfate reduction caused a 80% decrease in DMS consumption. When sulfate reduction and methanogenesis were simultaneously inhibited, DMS did not decrease. DMS contributed about 28% to the methane production rate, while DMS probably contributed only 1% or less to the sulfate reduction rate. Incubation of the sediment slurries under an atmosphere of air resulted in similar DMS consumption compared to anaerobic incubations, but MSH and CH 4 were not evolved. Sediments from the marsh released significant quantities of DMS when treated with cold alkali, indicating that potentially significant sources of DMS existed in the sediments. Values of base-hydrolyzable DMS as high as 190 μmol per liter of sediment were observed near the sediment surface, and values always decreased with depth in the sediment. Simple flux experiments with small intact sediment cores, showed that DMS was emitted from the marsh surface when cores were injected with glutaraldehyde or molybdate and 2-bromoethanesulfonate (BES), but nit when cores were left uninhibited. These results showed that DMS was readily metabolized by microbes in marsh sediments and that this metabolism may be responsible for reducing the emission of DMS from the marsh surface.

Sediment ammonium availability and eelgrass (Zostera marina) growth

The interaction of sediment ammonium (NH 4 + ) availability and eelgrass (Zostera marina L.) growth, biomass and photosynthesis was investigated using controlled environment and in-situ manipulations of pore water ammonium concentrations. Sediment diffusers were used to create pore water diffusion gradients to fertilize and deplete ammonium levels in sediments with intact eelgrass rhizospheres. Between October, 1982 and September, 1983 controlled environment experiments using plants from shallow (1.3 m) and deep (5.5 m) stations in a Great Harbor, Woods Hole, Massachusetts, USA eelgrass meadow along with in-situ experiments at these stations provided a range of sediment ammonium concentrations between 0.1 and 10 mM (adsorbed+interstitial NH 4 + ). The results of the in-situ experiments indicate that nitrogen limitation of eelgrass growth does not occur in the Great Harbor eelgrass meadow. A comparison of NH 4 + regeneration rates and eelgrass nitrogen requirements indicates an excess of nitrogen supply over demand and provides an explanation for the lack of response to the manipulations. Results of controlled environment experiments combined with in-situ results suggest that sediment ammonium pool concentrations above approximately 100 μmol NH 4 + per liter of sediment (interstitial only) saturate the growth response of Zostera marina.

Flowthrough Reactor Flasks for Study of Microbial Metabolism in Sediments

Flowthrough reactor flasks are described that allow continuous low-level nutrient input to mixed anoxic sediments without dilution of the sediment. The flasks were tested by simulating sulfate inputs into sediments collected from a freshwater eutrophic lake. After an initial 2-day adaptation within the reactor system, rates of methane production and sulfate consumption were constant for the duration of a 12-day incubation. A sulfate input rate of 0.15 mmol liter of sediment day resulted in an equivalent rate of sulfate removal, which was unaffected by inputs of acetate (1.0 mmol liter of sediment day). The rate of methane production in control reactors, 0.18 mmol liter of sediment day, was doubled by the addition of acetate, whereas sulfate consumption was only stimulated by additions of high concentrations of sulfate plus acetate (1.5 and 1.0 mmol liter of sediment day, respectively). The reactor system appears to be effective in maintaining the balance between sulfate reduction and methane production in freshwater sediments and is potentially useful for study of the response of sediment populations to varying inputs of naturally occurring substrates, selected inhibitors, or xenobiotic compounds.

Effect of Fall Turnover on Terminal Carbon Metabolism in Lake Mendota Sediments

The carbon and electron flow pathways and the bacterial populations responsible for the transformation of H(2)-CO(2), formate, methanol, methylamine, acetate, ethanol, and lactate were examined in eutrophic sediments collected during summer stratification and fall turnover. The rate of methane formation averaged 1,130 mumol of CH(4) per liter of sediment per day during late-summer stratification versus 433 mumol of CH(4) per liter of sediment per day during the early portion of fall turnover, whereas the rate of sulfate reduction was 280 mumol of sulfate per liter of sediment per day versus 1,840 mumol of sulfate per liter of sediment per day during the same time periods, respectively. The sulfate-reducing population remained constant while the methanogenic population decreased by one to two orders of magnitude during turnover. The acetate concentration increased from 32 to 81 mumol per liter of sediment while the acetate transformation rate constant decreased from 3.22 to 0.70 per h, respectively, during stratification versus turnover. Acetate accounted for nearly 100% of total sedimentary methanogenesis during turnover versus 70% during stratification. The fraction of CO(2) produced from all C-labeled substrates examined was 10 to 40% higher during fall turnover than during stratification. The addition of sulfate, thiosulfate, or sulfur to stratified sediments mimicked fall turnover in that more CO(2) and CH(4) were produced. The addition of Desulfovibrio vulgaris to sulfate-amended sediments greatly enhanced the amount of CO(2) produced from either [C]methanol or [2-C]acetate, suggesting that H(2) consumption by sulfate reducers can alter methanol or acetate transformation by sedimentary methanogens. These data imply that turnover dynamically altered carbon transformation in eutrophic sediments such that sulfate reduction dominated over methanogenesis principally as a consequence of altering hydrogen metabolism.

Influence of pH on Terminal Carbon Metabolism in Anoxic Sediments from a Mildly Acidic Lake

The carbon and electron flow pathways and the bacterial populations responsible for transformation of H(2)-CO(2), formate, methanol, methylamine, acetate, glycine, ethanol, and lactate were examined in sediments collected from Knaack Lake, Wis. The sediments were 60% organic matter (pH 6.2) and did not display detectable sulfate-reducing activity, but they contained the following average concentration (in micromoles per liter of sediment) of metabolites and end products: sulfide, 10; methane, 1,540; CO(2), 3,950; formate, 25; acetate, 157; ethanol, 174; and lactate, 138. Methane was produced predominately from acetate, and only 4% of the total CH(4) was derived from CO(2). Methanogenesis was limited by low environmental temperature and sulfide levels and more importantly by low pH. Increasing in vitro pH to neutral values enhanced total methane production rates and the percentage of CO(2) transformed to methane but did not alter the amount of CO(2) produced from [2-C]acetate ( approximately 24%). Analysis of both carbon transformation parameters with C-labeled tracers and bacterial trophic group enumerations indicated that methanogenesis from acetate and both heterolactic- and acetic acid-producing fermentations were important to the anaerobic digestion process.

LONG-TERM INVESTIGATIONS ON CHEMICAL AND MICROBIAL CHANGES OF A SLIGHTLY OIL POLLUTED BEACH1

ABSTRACT A sandy and muddy beach polluted by Arabian light crude oil in 1974 was investigated in 1974, 1975, and 1981. The shift of the hydrocarbon contamination from the sand to the mud has been determined by infrared spectroscopy and glass capillary gas chromatography. In 14 months, the mean values of the hydrocarbon content in the sandy beach declined from 203 milligrams per liter (mg/l) to 10 mg/l. However, those of the mud flat increased by 300 percent (from 37 mg/l to 108 mg/l). Six years later, the fossil fuel hydrocarbon concentration had decreased to 0.6 mg/l and 8 mg/l for the sandy and muddy beach, respectively. Nevertheless, both areas still reflect the former polluting event. This was established definitively by the trace analysis of acyclic isoprenoid alkanes (norpristane, pristane, phytane) which indicates oil contamination by detection of mature diastereoisomers. The bacteria reflect the fate of the hydrocarbons. The numbers of oil degraders rapidly increased by several orders of magnitude within the first weeks and reached maximum values well above 1011 per liter of sediment. Simultaneously, the overall ratio of oil-degrading bacteria to normal heterotrophs topped 270 percent, decreasing gradually to the normal background value within one year. The highest ratio of oil degraders was found in the sandy beach shortly after the spill and in the muddy beach after several months.

Reduction of Sulfur Compounds in the Sediments of a Eutrophic Lake Basin

Concentrations of various sulfur compounds (SO(4), H(2)S, S, acid-volatile sulfide, and total sulfur) were determined in the profundal sediments and overlying water column of a shallow eutrophic lake. Low concentrations of sulfate relative to those of acid-volatile sulfide and total sulfur and a decrease in total sulfur with sediment depth implied that the contribution of dissimilatory sulfur reduction to H(2)S production was relatively minor. Addition of 1.0 mM Na(2)SO(4) to upper sediments in laboratory experiments resulted in the production of H(2)S with no apparent lag. Kinetic experiments with S demonstrated an apparent K(m) of 0.068 mmol of SO(4) reduced per liter of sediment per day, whereas tracer experiments with S indicated an average turnover time of the sediment sulfate pool of 1.5 h. Total sulfate reduction in a sediment depth profile to 15 cm was 15.3 mmol of sulfate reduced per m per day, which corresponds to a mineralization of 30% of the particulate organic matter entering the sediment. Reduction of S occurred at a slower rate. These results demonstrated that high rates of sulfate reduction occur in these sediments despite low concentrations of oxidized inorganic compounds and that this reduction can be important in the anaerobic mineralization of organic carbon.

Biogenic Graded Bedding

ABSTRACT Graded beds may be produced by deposit-feeding organisms in intertidal and shallow subtidal environments. Barnstable Harbor, Cape Cod, Massachusetts, contains intertidal populations of Clymenella torquata, a sedentary polychaete. Clymenella selectively ingests specific size fractions of sediment at a depth of 10-30 cm within the tidal flats. Sand and silt are transported vertically through the gut and egested as uncompacted feces on the sediment surface. Size fractions too coarse for ingestion ( > 1.0 mm) are concentrated at the lower end of worm tubes producing a well graded stratum. Laboratory measurements indicate that Clymenella is capable of displacing 87 liters of sediment per m2 per year at the mean annual water temperature of Barnstable Harbo (11°C). The thickness of a graded bed, limited by feeding depth, is less than 30 cm. Maximum and average grain size decrease in regular fashion from the base to the top of the bed. Sorting is poor and values vary irregularly in the bed. The size distribution curves are strongly to moderately fine-skewed in samples at the base of beds; curves become more nearly symmetrical at the top of graded beds. Biogenically graded beds may be distinguished from physically deposited graded beds by textural properties, associated sedimentary structures, geometry of the deposits, and lithology of interfingering facies. The best development of biogenic graded bedding occurs in sites of slow hysical sediment accretion and relatively weak bottom currents.