Search results for "Anoxic waters"
showing 10 items of 77 documents
Sediment quality assessment using Gmelinoides fasciatus and Monoporeia affinis (Amphipoda, Gammaridea) in the northeastern Baltic Sea
2013
Crustaceans in the order Amphipoda are sensitive organisms for the assessment of sediment quality. In this work we performed 10-day toxicity tests on muddy sediments collected from a total of 29 sites in the Gulf of Finland, the Gulf of Riga and the Gulf of Bothnia (northeastern Baltic Sea) using Baltic Sea species such as the native amphipod Monoporeia affinis (Bousfield, 1989) and the invasive amphipod Gmelinoides fasciatus (Stebbing, 1899), and also compared these results with those of bioassays carried out using the standard test species, laboratory-cultivated amphipod Hyalella azteca (Saussure, 1858). The sediment samples (three cm of the upper layer) were collected by a GEMAX Dual Cor…
Green sulphur bacteria as a component of the photosynthetic plankton community in small dimictic humic lakes with an anoxic hypolimnion
2013
High bacteriochlorophyll (BChl) concentrations in the anoxic water layers of some humic lakes have indicated that green sulphur bacteria (GSB) may be ecologically significant. The abundance and spatial distribution of GSB were therefore addressed in 13 small humic lakes using fragment analysis and sequencing of PCR-amplified 16S rRNA genes. GSB were detected from lakes where the photosynthetically active radiation was at least 1.1 µE m �2 s �1 at the oxic� anoxic boundary layer. In these lakes, 13 to 42% of the 16S rRNA gene sequences of the anoxic water column were assigned to GSB. The spatial distribution of GSB was tightly correlated with the spectrophotometrically measured BChl concentr…
Speciation and oxidation kinetics of arsenic in the thermal springs of Wiesbaden spa, Germany.
2001
Since 1886 arsenic has been known to be present as a trace component in the Wiesbaden thermal waters at concentrations of over 100 microg L(-1). In this study for the first time molecular level speciation of arsenic was measured both in the water (by HG-AAS) and in wellstone scale deposits (by XANES). Most of the arsenic in the anoxic NaCl-type waters is in the reduced arsenite form. Hydrous ferric oxide (HFO) precipitates in the scale deposits scavenge only the minor dissolved arsenate portion which is, however, accumulated up to 3% w/w. Isothermal precipitation experiments at in-situ temperatures showed a difference between the progress of both arsenic and iron oxidation and precipitation…
Bacterial Community Structure of an IFAS-MBRs Wastewater Treatment Plant
2017
TIn this work, the bacterial community putatively involved in BNR events of a UCT-MBMBR pilot plant was elucidated by both culture-dependent and metagenomics DNA analyses. The presence of bacterial isolates belonging to Bacillus (in the anoxic compartment) and to Acinetobacter, Stenotrophomonas, Rhodococcus, Escherichia and Aeromonas (in the aerobic compartment) is in agreement with the nitrification/denitrification processes observed in the plant. Moreover, the study of bacterial community structure by NGS revealed a microbial diversity suggesting a biochemical complexity which can be further explored and exploited to improve UCT-MBMBR plant performance.
Modelling biogeochemical processes in sediments from the north western Adriatic Sea: response to enhanced POC fluxes
2017
Abstract. This work presents the result of a study carried out in the north-western Adriatic Sea, by combining two different types of biogeochemical models with field sampling efforts. A longline mussel farm was taken as a local source of perturbation to the natural POC downward flux. This flux was first quantified by means of a pelagic model of POC deposition coupled to sediment traps data, and its effects on sediment bioirrigation capacity and OM degradation pathways were investigated by constraining an early diagenesis model, linked to new data in sediment porewaters. The measurements were performed at stations located inside and outside the area affected by mussel farm deposition. Model…
Interspecies interactions mediated by conductive minerals in the sediments of the ferruginous Lake La Cruz, Spain
2018
AbstractLake La Cruz is considered a biogeochemical analogue to early Earth marine environments because its water column is depleted in sulfate, but rich in methane and iron, similar to conditions envisaged for much of the Precambrian. In this early Earth analogue environment, we show that conductive particles establish a tight metabolic coupling between electroactive microbial clades. We propose that mineral-based syntrophy is of potential relevance for the evolution of Earth’s earliest complex life forms. We show that the anoxic sediment of Lake La Cruz, which is rich in biogeochemically ‘reactive’ iron minerals, harbors known electroactive species such asGeobacterandMethanothrix,in addit…
Mineralogy and geochemistry of Mesozoic black shales and interbedded carbonates, southeastern Sicily: evaluation of diagenetic processes
1993
AbstractUpper Triassic/Lower Jurassic organic-rich shales and interbedded carbonates (Rhaetian → Sinemurian) are widespread in the subsurface of southeastern Sicily where important oil fields have been found hosted in Triassic reservoirs. Core samples from wells drilled offshore and onshore were studied from petrographie and geochemical viewpoints.In the Hettangian/Sinemurian shale-carbonate sequences, which accumulated in a rapidly subsiding basin, the micritic aragonitic mud is still largely preserved. Mixed-layer I/S has remained randomly interstratified to a depth > 4000 m. Diagenetic carbonates are non-stoichiometric finely crystalline, pore-filling dolomite and/or calcite. The carb…
Calibration and validation of activated sludge model No.2d for Spanish municipal wastewater.
2002
Activated Sludge Model No. 2d (ASM2d) was validated with data obtained from pilot scale plant treating municipal wastewater from the city of Valencia (Spain). First of all, ASM2d was calibrated using experimental data from anaerobic, anoxic and aerobic batches. A set of kinetic and stoichiometric parameters resulted from these assays. Differences between the values obtained and default values proposed in ASM2d can be explained by the presence of glycogen accumulating organisms (GAOs). The calibrated model was then used to simulate results from a pilot plant. Simulation using the set of parameters obtained accurately reproduces experimental results. This paper also presents a detailed proced…
Anaerobic ciliates from a sulphide-rich solution lake in Spain
1991
We have examined and quantified the anaerobic ciliates living in the hypolimnion of a 14 m deep sulphide-rich (up to 0.73 mM) solution lake in Spain. At least seven ciliate species were found, numbering up to 50 ml-1 in total and reaching maximum abundance close to the sediment. Caenomorpha medusula, Lacrymaria elegans, L. sapropelica and Lagynus sp. were the most abundant species. Their vertical distributions were not related to the sulphide profile. Most ciliates were dependent on the sedimentation of cryptomonads, photosynthetic bacteria (especially Chromatium and Oscillatoria) and other bacteria from their sites of production in closely-juxtaposed mid-water plates. All anaerobic ciliate…
Population response during an Oceanic Anoxic Event: The case of Posidonotis (Bivalvia) from the Lower Jurassic of the Neuquén Basin, Argentina
2019
Benthonic marine species show a wide range of biological reactions to seawater chemical changes through time, from subtle adjustments to extinction. The Early Toarcian Oceanic Anoxic Event (T-OAE) was recently recognized in the Neuquén Basin, Argentina, confirming its global scope. The event was identified chemostratigraphically on the basis of a relative increase in marine organic carbon and a characteristic negative carbon-isotope excursion (δ13Corg) in bulk rock and fossil wood in the upper Pliensbachian–lower Toarcian interval in the Arroyo Lapa section (Neuquén). Simultaneously with collection of lithological samples, a high-resolution biostratigraphical survey was carried out, and the…