Seasonal variations in the vertical distribution and buoyancy of Microcystis aeruginosa Kütz. emend. Elenkin in Rostherne Mere,England

Distribution and buoyancy studies in Rostherne Mere (depth: 30m) show that the life-cycle of Microcystis is intimately related to the cycle of thermal stratification: colonies overwinter on the bottom muds, but migrate to the epilimnion in summer, returning again in late autumn or winter.     

Sediment dispersion: part 2, characterisation by size of sand fraction and percent mud

In part 2 of this contribution, examples are drawn from the River Mersey and Liverpool Bay illustrating the use of simple statistical parameters to describe dispersion of sands and muddy sediments. The River Mersey and Liverpool Bay, eastern Irish Sea, were sites of intensive studies on the dispersal of dumped harbour mud and sewage sludge during the mid 1960's–70's. The combined effects of strong tidal scour, wave action and shoreward near-bed residual drift result in shoreward transport of large volumes of sand in the bay. Large amounts of mud (silt/clay mixtures) oscillate in the river estuary, and naturally derived and dumped muds also move shoreward in the bay. Unpublished historic geochemical data have been combined with reprocessed particle size data and both have been used to reassess sedimentological techniques for defining transport and dispersal pathways. River and bay muds have similar size compositions, but river muds have excess Cd > V > U > As = Zn relative to bay muds. The lower relative concentrations of heavy metals in the bay are thought to reflect desorption and degradation of organic matter from the river. Trends in sediment distribution data based on the means of the sand size fraction, alone, provide sensitivities comparable to those of higher order moment measures and are usually easier to interpret than full size spectrum analyses.     

Influence of the drilling mud formulation process on the bacterial communities in thermogenic natural gas wells of the Barnett Shale

The Barnett Shale in north central Texas contains natural gas generated by high temperatures (120 to 150°C) during the Mississippian Period (300 to 350 million years ago). In spite of the thermogenic origin of this gas, biogenic sulfide production and microbiologically induced corrosion have been observed at several natural gas wells in this formation. It was hypothesized that microorganisms in drilling muds were responsible for these deleterious effects. Here we collected drilling water and drilling mud samples from seven wells in the Barnett Shale during the drilling process. Using quantitative real-time PCR and microbial enumerations, we show that the addition of mud components to drilling water increased total bacterial numbers, as well as the numbers of culturable aerobic heterotrophs, acid producers, and sulfate reducers. The addition of sterile drilling muds to microcosms that contained drilling water stimulated sulfide production. Pyrosequencing-based phylogenetic surveys of the microbial communities in drilling waters and drilling muds showed a marked transition from typical freshwater communities to less diverse communities dominated by Firmicutes and Gammaproteobacteria. The community shifts observed reflected changes in temperature, pH, oxygen availability, and concentrations of sulfate, sulfonate, and carbon additives associated with the mud formulation process. Finally, several of the phylotypes observed in drilling muds belonged to lineages that were thought to be indigenous to marine and terrestrial fossil fuel formations. Our results suggest a possible alternative exogenous origin of such phylotypes via enrichment and introduction to oil and natural gas reservoirs during the drilling process.     

Effects of sedimentation from water-based drill cuttings and natural sediment on benthic macrofaunal community structure and ecosystem processes

In this study, we aim at investigating the role of physical disturbance in effects of water-based drill cuttings on benthic ecosystems. Today, most of the cuttings discharged from oil and gas installations contain water-based drilling muds, rather than oil-based or synthetic muds. Drill cuttings with water-based muds are assumed to cause only marginal effects on the benthos, mainly resulting from sedimentation. However, this statement has not been experimentally tested, which is the purpose of the present work. Natural sediment particles and water-based drill cuttings were added to benthic communities in layer thicknesses of 3-24 mm in a mesocosm set-up. During the following 6 months, changes in benthic community structure and fluxes of oxygen and nutrients across the sediment water interface were studied. There was a significant reduction in number of taxa, abundance, biomass and diversity of macrofauna with increasing thickness of drill cuttings, which was not observed for the natural sediment particles. The drill cuttings also influenced oxygen consumption and oxygen penetration depth in the sediment, and it was concluded that an organic compound in the drill cuttings initiated a typical eutrophication response. Fluxes of phosphate and silicate were, however, similarly affected by the two types of particles, and maximum fluxes occurred in sediments treated with thin layers (3-6 mm) of particles. As the response of water-based drill cuttings in the present study was a result of factors other than physical disturbance, we recommend a reconsideration of the assumption that water-based drill cuttings only cause sedimentation (burial) effects.     

Anaerobic metabolic processes in the deep terrestrial subsurface

Anaerobic microorganisms were enumerated and metabolic activities measured in deep Coastal Plain sediments sampled from three water‐bearing formations at depths down to 300 m. Aseptically obtained sediment cores harbored the potential for anaerobic biodegradation of various substrates in almost all samples. Although the sediments were not predominantly anaerobic, viable methanogens and sulfate‐reducing bacteria (SRB) were present almost throughout the depth profile. Coliform organisms were also found at various locations, but were not recoverable from drilling muds or water used to slurry the muds. The anaerobic metabolism of lactate and formate was easily detected in most samples. However, acetate and benzoate were degraded only in portions of the subsurface that harbored methanogens. The water‐saturated transmissive zones harbored the highest numbers of SRB and the potential for the widest variety of anaerobic metabolic activities. Small or negligible anaerobic microbial activity was associated with thick clay layers. The accumulation of acetate and the production of methane in samples not amended with exogenous organic matter demonstrated that some strata contained reserves of fermentable carbon and suggested that environmental factors or nutrients other than carbon were potentially limiting in situ microbial activity.     

Facies and faunal assemblage changes in response to the Holocene transgression in the Lagoon of Mayotte (Comoro Archipelago, SW Indian Ocean)

This paper documents the facies change in response to the Holocene transgression within five sediment cores taken in the lagoon of Mayotte, which contain a Type-1 depositional sequence (lowstand, transgressive and highstand deposits underlain by an erosive sequence boundary). Quantitative compositional analysis and visual examination of the bioclasts were used to document the facies changes. The distribution of the skeletal and non-skeletal grains in the lagoon of Mayotte is clearly controlled by (1) the rate and amplitude of the Holocene sea-level rise, (2) the pre-Holocene basement topography and (3) the growth-potential of the barrier reef during sea-level rise, and the changes in bathymetry and continuity during this period. The sequence boundary consists of the glacial karst surface. The change-over from the glacial lowstand is marked by the occurrence of mangrove deposits. Terrigenous and/or mixed terrigenous-carbonate muds to sandy muds with a mollusc or mollusc-ostracod assemblage dominate the transgressive deposits. Mixed carbonate-siliciclastic or carbonate sand to gravel with a mollusc-foraminifer or mollusc-coral-foraminifer assemblage characterize the early highstand deposits on the inner lagoonal plains. The early highstand deposits in the outer lagoonal plains consist of carbonate muds with a mollusc-foraminifer assemblage. Late highstand deposits consist of terrigenous muds in the nearshore bays, mixed terrigenous-carbonate sandy muds to sands with a mollusc-foraminifer assemblage on the inner lagoonal plains and mixed muds with a mollusc-foraminifer assemblage on the outer deep lagoonal plains. The present development stage of the individual lagoons comprises semi-enclosed to open lagoons with fair or good water exchange with the open ocean.     

The tom-tom corer: a new design of the Kajak corer for use in meiofauna sampling

A new corer, the tom-tom, is a modification of the basic Kajak design. New modifications increase the efficiency of the corer in soft muds and increase the stability of the corer during ascent and descent. A stepped release trigger mechanism allows the corer to trip easily in even the softest muds, and a Phleger “bomb’ weight adds stability to the device. The corer can be deployed in a slow, controlled descent from small as well as large boats to reduce bow-wave. Four cores (4.50 cm inner diameter) are taken simultaneously in a fixed spatial pattern. Limited comparative sampling revealed that the tom-tom collected more meiofauna than a Van Veen grab and attained numbers statistically indistinguishable from diver-collected cores (only small sample sizes were available however). The corer will be most efficient in sediments without an extremely well-developed, suspendable layer, and most practical for smaller vessels in environments where diver collected cores are precluded by depth, strong currents or poor visibility. Although used in meiofauna collection, the corer should be appropriate for any sampling needs requiring a relatively undisturbed core.     

Submarine erosion on a gentle paleoslope: a study of two discontinuities in the New York Devonian

Two diastems in the King Ferry Shale Member (Ludlowville Formation) are the result of local submarine erosion. These discontinuities, traceable from the Cayuga Valley to Seneca Lake, are marked by bioencrusted hiatus-concretions, and both diastems display westward erosional overstep of underlying beds. Hiatus-concretions show complex sequential histories of in situ formation, exhumation, and biodegradation. Activity of bottom organisms influenced erosion; substrate modification by infauna acted to trigger or accelerate sediment loss in a low energy setting. Both diasterns are developed along a depth related paleoenvironmental gradient; submarine erosion in this area is controlled, in part, by the presence of a gentle northwest dipping paleoslope. Juxtaposition of three conditions: bioturbation of surface muds, episodic wave or current impingement on these muds, and substrate inclination resulted in local sea floor erosion through a process of downslope sediment transport and dispersion. King Ferry diastems are termed stratomictic . Stratomictic discontinuities are erosional breaks which lack discrete hiatal surfaces due to vertical sediment mixing by infauna. They include several other examples from the New York Devonian and probably have analogs in numerous sedimentary sequences world-wide.     

Nitrogen-fixing phylotypes of Chesapeake Bay and Neuse River estuary sediments

Sediments often exhibit low rates of nitrogen fixation, despite the presence of elevated concentrations of inorganic nitrogen. The organisms that potentially fix nitrogen in sediments have not previously been identified. Amplification of nifH genes with degenerate primers was used to assess the diversity of diazotrophs in two distinct sediment systems, anoxic muds of Chesapeake Bay and shallow surficial sediments of the Neuse River. Phylogenetic analysis revealed that sequences obtained from mid-Chesapeake Bay, which receive high organic loading and are highly reducing, clustered closely with each other and with known anaerobic microorganisms, suggesting a low abundance of aerobic or facultative diazotrophs in these sediments. Sulfate reduction dominates in the surface, but methanogenesis becomes more important with depth. A thin (<1 cm) oxidized layer is present only in the spring. No archaeal nifH sequences were obtained from Chesapeake Bay. Sequences of nifH amplified from surficial sediments of the Neuse River were distant from Chesapeake Bay sequences and included nif phylotypes related to sequences previously reported from marine mats and the Spartina rhizosphere. Differences in environmental site characteristics appear to select for different types of sediment diazotrophs, which is reflected in the phylogenetic composition of amplified nifH sequences.     

The antibacterial activity of a humic preparation made from the therapeutic peat mud of the Dzalal Abad deposit in Kirghizia]

The humic acid from the Dzhalal Abad therapeutic peat muds has been extracted to reveal the mechanisms of interaction between humic acid and microelements in therapeutic muds and to study the mud physiologically active factor. A complex compound of copper with humic and aminoacetic acids has been obtained, their physicochemical and antibacterial properties have been studied.     

Actinomycetes in lake muds: dormant spores or metabolically active mycelium?

Homogenization and ultrasonication experiments on samples of lake muds indicated that Micromonospora strains were present as a mixture of mycelium and spores. In contrast, strains of streptomycetes and nocardioforms appeared to be in the form of arthrospores or fragmentation spores respectively. Micromonospora strains originally isolated from lakes were able to grow in both native and enriched muds incubated in the laboratory. Numbers of streptomycetes and nocardioforms did not increase in these muds and are presumed to be relatively inactive in this habitat. We postulate that Micromonospora strains have an active role in the lacustrine environment as well as in soil.     

Ceramic processing of polluted dredged mud

About 45 million m³ of bottom sediment, with an estimated dry matter content of 30%, have to be dredged annually in the Netherlands, of which several million m³ are strongly contaminated with heavy metals and toxic organic substances. Contaminated dredged muds are dumped in special locations on land.The problems of severely polluted muds are likely to remain from many decades to come, and the present disposal reserve may not be adequate. In a densely populated country, large-scale disposal on land is not a satisfactory long-term solution, and a method of cleaning these muds has to be developed. This paper presents some of the results of an investigation into the feasibility of ceramically processing severely polluted dredged muds. Ceramic processing not only destroys the organic micro-pollutants; the leaching of heavy metals is reduced by ceramic bonding and the end-product is a hard, lightweight gravel-size particulate, useful as a building material. Extensive tests have been carried out on the leaching behaviour of the ceramic products and the results showed little or no differences in comparison with other commonly used building materials; the results are better than those of aggregates made from pulverized fuel ashes.     

The occurrence and distribution of actinomycetes in lakes of the English Lake District

Investigation of the occurrence of mesophilic actinomycetes in the lakes of the English Lake District revealed their widespread distribution in the lacustrine environment. Although only low numbers of actinomycetes occurred in the water, high numbers were recovered from all the lake muds. Total numbers of actinomycetes in the muds correlated quite well with the lakes’ productivity status. High numbers of Micro-monospora, Streptomyces and nocardioform actinomycetes were isolated from all the lakes sampled. Low numbers of Streptosporangium were isolated from all the muds but strains of Actinomadura, Actinoplanes, Dactylosporangium, Microbispora and Thermomonospora were only encountered occasionally. Micromonospora was the numerically dominant genus isolated from all the lakes sampled. This dominance was even more striking in deeper layers of mud and this was thought to reflect a more resistant spore stage in Micromonospora than in either of the other two main genera.     

The distribution of sulphur in the muds,water and vegetation of Lake Victoria

Summary The sulphur contents of the muds, water and vegetation at the northern end of Lake Victoria have been determined. Contrary to previous assumptions it was found that the sulphur in the bottom deposits is principally in the form of organic compounds and not as sulphides. Evidence is presented which suggests that the muds are in an aerated condition. The water of the lake contains extremely small amounts of sulphur and receives a negligible quantity of this element from the rain. The soils of the islands in the lake are rocky and well-leached of sulphur except where patches of forest conserve it. Certain peculiarities were noted in the behaviour of the muds and these are to be discussed in a future paper.     

Evidence for the Occurrence of Specific Iron (III)-Binding Compounds in Near-Shore Marine Ecosystems

Aqueous extracts of samples from representative types of near-shore marine ecosystems were examined for growth-promoting activity for the siderochrome auxotroph, Arthrobacter JG-9. Blue-green algal mat and sea grass samples gave strongly positive responses. Relative to Desferal (Ciba Pharmaceutical Co., Summit, N.J.), concentrations up to 110 ng/g (wet weight) of sample were found. In contrast, extracts of anaerobic muds or macroalgae gave no detectable activity. The hydroxamate type of iron chelator may be important in providing a form of iron in sea water readily utilized by the microalgae and marine higher plants.     

The importance of monitoring metabolic recovery in the coral Acropora cervicornis after short-term exposure to drilling muds: Calcification rate and protein concentration

The effect of used drilling muds on coral health was examined by monitoring changes in calcification rate and soluble tissue protein concentration in the coral Acropora cervicornis. Exposure to 25 ppm (v/v) of one mud for 24 h reduced calcification rate in the growing tips by as much as 62%. In recovery experiments, corals were exposed to drilling muds for 24 h; some of them were allowed to recover in clean seawater for 48 h. After the 24-hour exposure, calcification rates were significantly less than those of the controls. After a 48-hour recovery period, calcification rates returned to control levels for one mud but were still significantly below control levels for another. The results indicate that the capacity for recovery after exposure cannot be predicted from the results of experiments on exposure only. Recovery capacity must be independently verified for all studies on the effects of short-term exposure to drilling muds.     

Iron, Manganese, Ash, and Nitrogen in some Plants from Salt Marsh and Shingle Habitats

Analyses for iron, manganese, ash, and nitrogen are recordedfor some plants from salt marshes and shingle hooks. Ash ismuch higher, and iron and manganese are much lower, than inplants from underwater lake muds, woodland soils of varyinghumus content and acidity, and semi-aquatic marsh, fen, andbog soils. Since both lake muds and salt-marsh soils are deficientin oxygen, with iron and manganese presumably mobile as divalentions, the difference in concentration of the two elements inplants from the two types of habitat requires explanation. Itis suggested that the much greater total ion concentration ofthe salt-marsh soil solution may depress iron and manganeseassimilation through ionic antagonism.     

Meiofaunal prominence and benthic seasonality in a coastal marine ecosystem

Summary The muds of a shallow (7 m) site in Narragansett Bay, Rhode Island contained higher abundances of meiofauna (averaging 17×10⁶ individuals per m² and ash free dry weight of 2.9 g/m² during a 3 year period) than have been found in any other sediment. The majority of sublittoral muds, worldwide, have been reported to contain about 10⁶ individuals per m². This difference is attributed primarily to differences in sampling techniques and laboratory processing.Extremely high meiofaunal abundances may have also occurred because Narragansett Bay sediments were a foodrich environment. While the quantity of organic deposition in the bay is not unusually high for coastal waters, this input, primarily composed of diatom detritus, may contain an unusually high proportion of labile organics. Furthermore, meiofauna could have thrived because of spatial segregation of meiofauna and macrofauna. While meiofauna were concentrated at the sediment-water interface, most macrofauna were subsurface deposit feeders. Macrofaunal competition with, and ingestion of meiofauna may thus have been minimized.The seasonal cycles of meiofauna and macrofauna were similar. Highest abundances and biomass were observed in May and June and lowest values in the late summer and fall. Springtime increases of meiofaunal abundance were observed in all depth horizons, to 10 cm. We hypothesize that phytoplankton detritus accumulated in the sediment during the winter and early spring, and that the benthos responded to this store of food when temperatures rose rapidly in the late spring. By late summer, the stored detritus was exhausted and the benthos declined.     

On the age of the hominid fossils at the Sima de los Huesos, Sierra de Atapuerca, Spain: paleomagnetic evidence

We report new paleomagnetic data for the Middle Pleistocene hominid-bearing strata in the Sima de los Huesos, North Spain. Sediments (brown muds with human and bear fossils and the underlying sterile clayey and sandy unit) preserve both normal and reversed magnetic components. The sterile unit has exclusively reversed magnetization, dating back to the Matuyama Chron, and thus is Lower Pleistocene in age. The overlying fossiliferous muds have a dominant normal magnetization that overprints a partially resolved reversed magnetization. These data are compatible with one of the reversal events that occurred during the Brunhes Chron. Combined with the existing U-series dates and evidence from the macro- and microfauna, these paleomagnetic results suggest an age of the hominid fossils between 325 to 205 ka, whereas the underlying sand and silts are older than 780 ka.     

Plasmid Incidence in Bacteria from Deep Subsurface Sediments

Bacteria were isolated from deep terrestrial subsurface sediments underlying the coastal plain of South Carolina. A total of 163 isolates from deep sediments, surface soil, and return drill muds were examined for plasmid DNA content and resistance to the antibiotics penicillin, ampicillin, carbenicillin, streptomycin, kanamycin, and tetracycline. MICs of Cu²⁺, Cr³⁺, and Hg²⁺ for each isolate were also determined. The overall frequency of plasmid occurrence in the subsurface bacteria was 33%. Resistance was most frequent to penicillin (70% of all isolates), ampicillin (49%), and carbenicillin (32%) and was concluded to be related to the concentrations of the individual antibiotics in the disks used for assaying resistance and to the production of low levels of β-lactamase. The frequencies of resistance to penicillin and ampicillin were significantly greater for isolates bearing plasmids than for plasmidless isolates; however, resistance was not transferable to penicillin-sensitive Escherichia coli. Hybridization of subsurface bacterial plasmids and chromosomal DNA with a whole-TOL-plasmid (pWWO) probe revealed some homology of subsurface bacterial plasmid and chromosomal DNAs, indicating a potential for those bacteria to harbor catabolic genes on plasmids or chromosomes. The incidences of antibiotic resistance and MICs of metals for subsurface bacteria were significantly different from those for drill mud bacteria, ruling out the possibility that bacteria from sediments were derived from drill muds.