In Search of a Field-Based Relationship Between Benthic Macrofauna and Biogeochemistry in a Modern Brackish Coastal Sea

During several cruises in the southern Baltic Sea conducted in different seasons from 2014 to 2016, sediment cores were collected for the investigation of pore-water biogeochemistry and associated nutrient fluxes across the sediment-water interface. Six stations were positioned along a salinity gradient (ranging from 22 to 8) and covered various sedimentary habitats ranging from mud to sand. Integrated fluxes of nutrients in the supernatant water and sediment oxygen consumption were additionally derived from incubations of intact sediment cores. Subsequently, sediment from the pore-water and incubation cores was sieved for taxonomic identification and estimation of benthic macrofauna density. This combined dataset was used to determine the dominant factors influencing the vertical distribution of geochemical parameters in the pore-waters of the studied habitats and to find similarities and patterns explaining significant variations of solute fluxes across the sediment-water interface. A statistical relationship between the thickness of sulfide-free surface sediments, solute fluxes of sulfide, ammonium, and phosphate as well as oxygen consumption and taxonomic and functional characteristics of macrobenthic communities were tested. Our data and modeling results indicate that bioturbation and bioirrigation alter near-surface pore-water nutrient concentrations toward bottom water values. Besides sediment properties and microbial activity, the biogeochemical fluxes can further be explained by the functional structure of benthic macrofauna. Community bioturbation potential, species richness, and biomass of biodiffusers were the best proxies among the tested set of biotic and abiotic parameters and could explain 63% of multivariate total benthic flux variations. The effects of macrobenthos on ecosystem functioning differ between sediment types, specific locations and seasons. Both, species distribution and nutrient fluxes are temporally dynamic. Those natural patterns, as well as potential anthropogenic and natural disturbances (e.g., fishery, storm events), may cause impacts on field data in a way beyond our present capability of quantitative prediction, and require more detailed seasonal studies. The data presented here adds to our understanding of the complexity of natural ecosystem functioning under anthropogenic pressure

Solute Reservoirs Reflect Variability of Early Diagenetic Processes in Temperate Brackish Surface Sediments

Coastal marine sediments are a hotspot of organic matter degradation. Mineralization products of early diagenetic processes accumulate in the pore waters of the sediment, are subject of biological uptake and secondary biogeochemical processes and are released back into the water column via advective and diffusive fluxes across the sediment-water interface. Seven representative sites in the shallow coastal area of the southern Baltic Sea (15–45 m water depth), ranging from permeable sands to fine grained muds, were investigated on a seasonal basis for their key mineralization processes as well as their solid phase and pore water composition to identify the drivers for the variability of early diagenetic processes in the different sediment types. The sandy sediments showed about one order of magnitude lower organic carbon contents compared to the muds, while oxygen uptake rates were similar in both sediment types. Significantly higher oxygen uptake rates were determined in two near-shore muddy sites than in a deeper coastal muddy basin, which is due to higher nutrient loads and the corresponding addition of fresh algal organic matter in the near-shore sites. Pore water concentration profiles in the studied sediments were usually characterized by a typical biogeochemical zonation with oxic, suboxic, and sulfidic zones. An up to 15 cm thick suboxic zone was sustained by downward transport of oxidized material in which dissolved iron and phosphate indicate an intensive reduction of reactive Fe with the release of adsorbed phosphorus. While the geochemical zonation was stable over time in the muds of the studied deeper basin, high variability was observed in the muds of a near-coastal bay probably mainly controlled by sediment mixing activities. The sediments can be characterized by essentially two factors based on their near-surface benthic solute reservoirs: (1) their organic matter mineralization and solute accumulation efficiency and (2) their redox-state. Benthic solute reservoirs in the pore waters of the top decimeter were generally higher in the muddy than in the sandy sediments as the more permeable sands were prone to an intensive exchange between pore water and bottom water. The three studied muddy sites showed great dissimilarities with respect to their predominating redox-sensitive metabolites (dissolved iron, manganese, and sulfide). Surface-near advective transport like irrigation of permeable sands and rearrangement of cohesive muds had a particularly strong influence on early diagenetic processes in the studied sediments and were probably the most important cause for the spatiotemporal variability of their benthic solute reservoirs

Impact of Co atoms on the electronic structure of Bi2Te3 and MnBi2Te4 topological insulators

This work is devoted to an experimental investigation of the electronic structure of the surface of topological insulators of various stoichiometry during the adsorption of Co atoms. Changes in the surface electronic structure of Bi2Te3 and MnBi2Te4 systems upon deposition of Co atoms at various temperatures have been studied using the methods of angle-resolved photoemission spectroscopy, as well as X-ray photoelectron spectroscopy. It is suggested that binding of the adsorbed Co atoms to the substrate surface modifies Dirac point position. The observed changes are associated with the possible formation of magnetic Co-containing ordered surface alloys.This work was supported by the St. Petersburg State University, grant no. 73028629, the Russian Science Foundation, grant no. 18-12-00062, the Russian Foundation for Basic Research, grant nos. 20-32-70127, 21-52-12024, and 18-29-12094, the Science Development Foundation of the President of Azerbaijan, grant no. EIF-BGM-4-RFTF-1/2017-21/04/1-M-02, and in the framework of the state assignment of Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, and the Rzhanov Institute of Semiconductors Physics, Siberian Branch of the Russian Academy of Sciences.Peer reviewe

One-sludge denitri-nitrification system application in reconstruction of biological treatment plants in Russian Federation

The paper presents the main problems and their solutions in the reconstruction of treatment facilities in the Russian Federation. The results of research aimed the use of the stable system, which is based on nitrification activated sludge appliance, when the sludge contains bacteria-heterotrophic-nitrificators, are shown. The working process after the reconstruction was high effective (about 98% organic compounds removing, and about 99% ammonium nitrogen removing). Analysis of the treatment facilities after reconstruction proves theoretical assumptions about the system. These data confirm the stability of the developed technological schemes and give reasons to recommend it for further implementation of the reconstruction of treatment facilitie

Modern technologies of the removal of nutrients from sewage and the study of microbiological processes in their application

This work presents the results of microbiological studies aimed at exploring the deeper removal of ammonium nitrogen and phosphates from domestic wastewater. This document presents the results of the study of heterotrophic removal of ammonium nitrogen from wastewater for the single sludge technological scheme of biological wastewater treatment. We offered the method of deep wastewater treatment using feed material reinforced by steel wire. Steel wire in the feed material has a significant impact on the quantity and diversity of species composition of protozoans in activated sludge, and leads to intensive development of Chlorella sp. as well. © The Authors, published by EDP Sciences, 2017

Modern technologies of the removal of nutrients from sewage and the study of microbiological processes in their application

This work presents the results of microbiological studies aimed at exploring the deeper removal of ammonium nitrogen and phosphates from domestic wastewater. This document presents the results of the study of heterotrophic removal of ammonium nitrogen from wastewater for the single sludge technological scheme of biological wastewater treatment. We offered the method of deep wastewater treatment using feed material reinforced by steel wire. Steel wire in the feed material has a significant impact on the quantity and diversity of species composition of protozoans in activated sludge, and leads to intensive development of Chlorella sp. as well. © The Authors, published by EDP Sciences, 2017

Methods for Removing of Phosphates from Wastewater

The paper offers update information on wastewater removal from phosphates. The writers describe the most commonly used efficient methods to remove phosphates from wastewater based on principles of biology, chemistry, physical chemistry and biological chemistry. The paper presents the results of research on phosphate-removing wastewater treatment methods using iron-bearing reinforced charge material. © The Authors, published by EDP Sciences, 2017

Effective removal of nutrients from wastewater

The current information in the field of wastewater from phosphates and nutrients removal. The paper presents the results of research aimed at understanding the deep removal of phosphates from household wastewater. Provides a method for wastewater treatment using reinforced boot material. In this paper, we investigated metal corrosion in iron-loading materials under different operating conditions. The paper presents the results of scientific work dedicated to the removal of ammonia nitrogen from wastewater. Based on the results of research were built characteristics of the process of biological treatment with nitrification and denitrification of. The paper presents charts showing the operation of the cleaning system with nitrifying bacteria heterotrophs. The results of studies of processes of wastewater treatment from biogenic elements at small treatment plants that operate in seasonal mode are presented. © The Authors, published by EDP Sciences

Methods for Removing of Phosphates from Wastewater

The paper offers update information on wastewater removal from phosphates. The writers describe the most commonly used efficient methods to remove phosphates from wastewater based on principles of biology, chemistry, physical chemistry and biological chemistry. The paper presents the results of research on phosphate-removing wastewater treatment methods using iron-bearing reinforced charge material. © The Authors, published by EDP Sciences, 2017