Oxygen Gradients and Structure of the Ciliate Assemblages in Floodplain Lake

This paper presents the results of studies on the structure of the ciliate population in a freshwater lake. The classification of the ciliated communities based on the analysis of the distribution of ciliate population density in the lake along the oxygen gradients, taking into account their oxygen preferences, was proposed. It was shown that the distribution of ciliated protozoa in the space of a reservoir is determined not by such spatial units as the water column, bottom, and periphytal, but by the oxygen gradients. Four types of habitats with different oxygen regimes were distinguished: With stably high oxygen concentration, stably low oxygen concentration, stably oxygen-free conditions, and conditions with a high amplitude of diurnal oxygen variations. The location of these habitats in the space of the lake and their seasonal changes were determined. On the basis of the quantitative development of ciliate populations, zones of optima and tolerance ranges of some ciliate species in the oxygen gradient were established. The oxygen preferences were established for the species from four distinguished assemblages: Microoxyphilic, oxyphilic, euryoxyphilic, and anoxyphilic (anaerobic). The presence or the absence of a certain type of assemblage in the reservoirs depends solely on the parameters of the oxygen gradients. The diversity of the ciliated protozoa in water bodies also depends on the stability and diversity of the oxygen gradients

Semi-automatic conversion of BioProp semantic annotation to PASBio annotation

<p>Abstract</p> <p>Background</p> <p>Semantic role labeling (SRL) is an important text analysis technique. In SRL, sentences are represented by one or more predicate-argument structures (PAS). Each PAS is composed of a predicate (verb) and several arguments (noun phrases, adverbial phrases, etc.) with different semantic roles, including main arguments (agent or patient) as well as adjunct arguments (time, manner, or location). PropBank is the most widely used PAS corpus and annotation format in the newswire domain. In the biomedical field, however, more detailed and restrictive PAS annotation formats such as PASBio are popular. Unfortunately, due to the lack of an annotated PASBio corpus, no publicly available machine-learning (ML) based SRL systems based on PASBio have been developed. In previous work, we constructed a biomedical corpus based on the PropBank standard called BioProp, on which we developed an ML-based SRL system, BIOSMILE. In this paper, we aim to build a system to convert BIOSMILE's BioProp annotation output to PASBio annotation. Our system consists of BIOSMILE in combination with a BioProp-PASBio rule-based converter, and an additional semi-automatic rule generator.</p> <p>Results</p> <p>Our first experiment evaluated our rule-based converter's performance independently from BIOSMILE performance. The converter achieved an F-score of 85.29%. The second experiment evaluated combined system (BIOSMILE + rule-based converter). The system achieved an F-score of 69.08% for PASBio's 29 verbs.</p> <p>Conclusion</p> <p>Our approach allows PAS conversion between BioProp and PASBio annotation using BIOSMILE alongside our newly developed semi-automatic rule generator and rule-based converter. Our system can match the performance of other state-of-the-art domain-specific ML-based SRL systems and can be easily customized for PASBio application development.</p

Quantitative study of activated sludge population structure

A quantitative study of the population structure of activated sludge is an important component of biological wastewater treatment control. However, in the studying of live samples of the activated sludge, some complications arise, in particular, associated with the relatively short time of the subsample suitability. A subsample is the part of the sample that is placed on a glass slide and in which organisms are counted. The issue of optimization of counts of organisms with large amplitude of population density is considered. The results of counting ciliated protozoa in activated sludge were described. The samples were counted in 45 sub-samples of 25 µl each. An average of 10 counts was required to achieve high reliability in determining population densities with more than or equal to 1 specimen per 25 µl in sub-samples. For small population densities (less one specimen per 25 µl) of free-swimming, crawling, and sessile ciliates, 30 counts are necessary. When the density of colonial protozoan populations is established, the number of counts should be increased to 40, especially when colonies with significant differences in the number of zooids are found

A model for the consolidation of rafted sea ice

Rafting is one of the important deformation mechanisms of sea ice. This process is widespread in the north Caspian Sea, where multiple rafting produces thick sea ice features, which are a hazard to offshore operations. Here we present a one-dimensional, thermal consolidation model for rafted sea ice. We consider the consolidation between the layers of both a two-layer and a three-layer section of rafted sea ice. The rafted ice is assumed to be composed of layers of sea ice of equal thickness, separated by thin layers of ocean water. Results show that the thickness of the liquid layer reduced asymptotically with time, such that there always remained a thin saline liquid layer. We propose that when the liquid layer is equal to the surface roughness the adjacent layers can be considered consolidated. Using parameters representative of the north Caspian, the Arctic, and the Antarctic, our results show that for a choice of standard parameters it took under 15 h for two layers of rafted sea ice to consolidate. Sensitivity studies showed that the consolidation model is highly sensitive to the initial thickness of the liquid layer, the fraction of salt release during freezing, and the height of the surface asperities. We believe that further investigation of these parameters is needed before any concrete conclusions can be drawn about rate of consolidation of rafted sea ice features

Ratio of abundances of ciliates behavioral groups as an indicator of the treated wastewater impact on rivers

A method for assessing the degree of impact of wastewater treatment plant discharge on receiving rivers was proposed, based on the structural indicators of the population of ciliated protozoa. It was shown that the ratio of attached, crawling and free-swimming forms in bottom sediments changes under the influence of discharge. In the points subject to organic pollution, the share of attached filter-feeding bacteriovorous ciliates increases in the assemblage of ciliated protozoa. The proposed Attached Form Index (AFI) takes this ratio into account. The use of AFI makes it possible to assess the restructuring of the assemblage of ciliated protozoa under the influence of point sources of pollution, to establish a zone of negative influence of runoff, to assess the degree of restoration of the aquatic ecosystem, as the influence of the pollution source weakened

Contribution of prokaryotes and eukaryotes to CO2 emissions in the wastewater treatment process

Reduction of the greenhouse effect is primarily associated with the reduction of greenhouse gas (GHG) emissions. Carbon dioxide (CO2) is one of the gases that increases the greenhouse effect - it is responsible for about half of the greenhouse effect. Significant sources of CO2 are wastewater treatment plants (WWTPs) and waste management, with about 3% contribution to global emissions. CO2 is produced mainly in the aerobic stage of wastewater purification and is a consequence of activated sludge activity. Although the roles of activated sludge components in the purification process have been studied quite well, their quantitative contribution to CO2 emissions is still unknown. The emission of CO2 caused by prokaryotes and eukaryotes over the course of a year (taking into account subsequent seasons) in model sequencing batch reactors (SBR) is presented in this study. In this work, for the first time, we aimed to quantify this contribution of eukaryotic organisms to total CO2 emissions during the WWTP process. It is of the order of several or more ppm. The contribution of CO2 produced by different components of activated sludge in WWTPs can improve estimation of the emissions of GHGs in this area of human activity

A Raman spectroscopic study of arsenite and thioarsenite species in aqueous solution at 25°C

The Raman spectra of thioarsenite and arsenite species in aqueous solution were obtained at room temperature. Solutions at constant ΣAs + ΣS of 0.1 and 0.5 mol kg(-1 )were prepared with various ΣS/ΣAs ratios (0.1–9.0) and pH values (~7–13.2). Our data suggest that the speciation of As under the conditions investigated is more complicated than previously thought. The Raman measurements offer evidence for at least six separate S-bearing As species whose principal bands are centered near 365, 385, 390, 400, 415 and 420 cm(-1). The data suggest that at least two different species may give rise to bands at 385 cm(-1), bringing the probable minimum number of species to seven. Several additional species are possible but could not be resolved definitively. In general, the relative proportions of these species are dependent on total As concentration, ΣS/ΣAs ratio and pH. At very low ΣS/ΣAs ratios we also observe Raman bands attributable to the dissociation products of H(3)AsO(3)(aq). Although we were unable to assign precise stoichiometries for the various thioarsenite species, we were able to map out general pH and ΣS/ΣAs conditions under which the various thioarsenite and arsenite species are predominant. This study provides a basis for more detailed Raman spectroscopic and other types of investigations of the nature of thioarsenite species

Speciation of arsenic in sulfidic waters

Formation constants for thioarsenite species have been determined in dilute solutions at 25°C, ΣH(2)S from 10(-7.5 )to 10(-3.0 )M, ΣAs from 10(-5.6 )to 10(-4.8 )M, and pH 7 and 10. The principal inorganic arsenic species in anoxic aquatic systems are arsenite, As(OH)(3)(0), and a mononuclear thioarsenite with an S/As ratio of 3:1. Thioarsenic species with S/As ratios of 1 : 1,2 : 1, and 4 : 1 are lesser components in sulfidic solutions that might be encountered in natural aquatic environments. Thioarsenites dominate arsenic speciation at sulfide concentrations > 10(-4.3 )M at neutral pH. Conversion from neutral As(OH)(3)(0 )to anionic thioarsenite species may regulate the transport and fate of arsenic in sulfate-reducing environments by governing sorption and mineral precipitation reactions