scholarly journals Emerging Ecotone and Microbial Community of a Sulfidic Spring in the Reka River Near Škocjanske Jame, Slovenia

Diversity ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 655
Author(s):  
Janez Mulec ◽  
Andreea Oarga-Mulec ◽  
Sara Skok ◽  
Stanka Šebela ◽  
Rosana Cerkvenik ◽  
...  
Keyword(s):  
Field Measurements ◽  
Climatic Conditions ◽  
Geological Mapping ◽  
Dynamic Nature ◽  
Core Microbiome ◽  
Global Impact ◽  
Operational Taxonomic Units ◽  
Physico Chemical ◽  
Isotopic Analyses ◽  
Stable Isotopic

During long periods with no precipitation, a sulfidic spring (Smrdljivec) appears in the dry bed of the Reka River before sinking into the karst underground. The study characterizes the area’s geological setting, development of microbial communities and an ecotone, and impact on the vulnerable karst ecosystem. Geological mapping of the area, stable isotopic analyses, field measurements, and physico-chemical and toxicity analyses were applied to elucidate the environmental conditions. The spring’s microbial diversity was assessed using cultivation methods, microscopy, and metagenomics. Sulfur compounds in the spring probably originate from coal layers in the vicinity. Metagenomic analyses revealed 175 distinct operational taxonomic units in spring water and biofilms. Proteobacteria predominated in developed biofilms, and a “core” microbiome was represented by methylotrophs, including Methylobacter, Methylomonas, and Methylotenera. Diatoms represented an important component of biofilm biomass. A combination of environmental factors and climatic conditions allows the formation and accessibility of emerging biodiversity hotspots and ecotones. Details of their dynamic nature, global impact, and distribution should be highlighted further and given more protection.

Stable isotopes in planktonic and benthic foraminifera from Arctic Ocean surface sediments

1988 ◽  
Vol 25 (5) ◽  
pp. 701-709 ◽  
Author(s):  
A. E. Aksu ◽  
G. Vilks
Keyword(s):  
Surface Water ◽  
Arctic Ocean ◽  
Sea Water ◽  
Ocean Surface ◽  
The Arctic ◽  
Size Fractions ◽  
Isotopic Compositions ◽  
Isotopic Analyses ◽  
Stable Isotopic ◽  
Surface Water Salinity

Oxygen and carbon isotopic analyses have been performed on the tests of Planulina wuellerstorfi and three size fractions of sinistral Neogloboquadrina pachyderma recovered from 33 Arctic Ocean surface-sediment samples. Stable isotopic compositions of N. pachyderma are found to be dependent on the test size: larger specimens show considerable enrichment in both δ18O and δ18C. The difference between the isotopic compositions of the 63–125 and 125–250 μm size fractions in N. pachyderma can be explained by biogenic fractionation effects during foraminiferal test growth. Larger (250–500 μm) N. pachyderma displayed accretions of secondary calcite, i.e., the outermost shell contained significant amounts of inorganically precipitated magnesium calcite. Thus, larger foraminifera may not be suited for down-core stable isotopic studies. There is a difference of ~2‰ between δ18O values of surface samples from the eastern and western Arctic Ocean, reflecting large differences between surface-water salinity in these regions. Therefore, oxygen isotopic data may have limited use as a chronostratigraphic tool in down-core studies in the Arctic Ocean, but we can use them to infer past variations in surface-water salinities. Planulina wuellerstorfi also showed depletions of both δ18O and δ18C in its calcite tests relative to calcite precipitated in isotopic equilibrium with ambient sea water; these depletions ranged from −0.8 to −0.9‰ in δ18Oand −1.2 to −0.9‰ in δ18C. This taxon is found to deposit its shell very close to the δ18C of ΣCO2 of bottom waters.

Hygienic assessment of potential ecotoxicological risk of the use of new insecticide spiromesifen in agriculture of Ukraine

2021 ◽  
pp. 62-67
Author(s):  
I.V. Tkachenko ◽  
Keyword(s):  
Chemical Properties ◽  
Terrestrial Ecosystems ◽  
Field Studies ◽  
Climatic Conditions ◽  
Climatic Zones ◽  
Ecotoxicological Risk ◽  
Environmental Objects ◽  
Physico Chemical ◽  
Consumption Rates ◽  
Agricultural Use

Objective: The aim of our work was to study the potential ecotoxicological hazard of a new chemical from the class of tetramic and tetronic acid derivatives - the insecticide spiromesifen, taking into account its physico-chemical properties and impact on the environmental objects. Materials and methods: An assessment of the potential danger of spiromesifen use for ecosystems was carried out on the basis of the calculation of the ecotoxicological hazard (ecotox) by N.N. Melnikov’s method. The field studies were carried out in different agro-climatic zones of Ukraine. The treatment of vineyards and apple trees was carried out at the maximum consumption rates of spiromesifen. Results: According to the literary data and our research, it was found that in the soil-and-climatic conditions of Ukraine, the ecotoxicological risk, when using the new insecticide spiromesifen, is 10,000 times and 7,000 times low than the analogous characteristics of DDT. Ecotox abamectin is 154 times low than ecotox DDT. This makes preparations, based on these substances, more promising and competitive among other pesticides in agricultural use. We can conclude that spiromesifen does not pose a threat to terrestrial ecosystems and health of the population.

Research of Air Flows Dynamics at Construction Works in the Condition of Urban Built-Up Areas

2018 ◽  
Vol 875 ◽  
pp. 183-186 ◽  
Author(s):  
I.V. Stefanenko ◽  
Valery N. Azarov ◽  
Katerina A. Trokhimchuk ◽  
Marina V. Trokhimchuk
Keyword(s):  
Dust Emission ◽  
Physical And Mechanical Properties ◽  
Simulation Modelling ◽  
Climatic Conditions ◽  
Fine Dust ◽  
Software Applications ◽  
Physico Chemical ◽  
Anthropogenic Development ◽  
Air Flows ◽  
Construction Works

The paper shows that the fulfillment of construction works influences the level of fine dust content in urban environment. Investigations of fine dust emissions in the zones of earth excavations and soil spoil banks caused by construction works were carried out. The authors conducted an integrated investigation of the physico-chemical processes in the surface layer of the atmosphere in the course of construction works, which was based on the field and computational experiments. With the help of a laboratory wind-tunnel plant, it was revealed that the character of dust emission during the development of dispersive massifs depends on the climatic conditions, in particular on the wind velocity and the physical-and-mechanical properties of the rocks (humidity, porosity, plasticity indices). A specific-purpose GIS application has been designed which allows modelling the dynamics of air flows in the territories with anthropogenic development. The application is based on the methods of mathematical and simulation modelling, the methods of visualization and surface plotting as well as the methods of software applications development.

Tracing the geographical origin of rice by stable isotopic analyses combined with chemometrics

2020 ◽  
Vol 313 ◽  
pp. 126093 ◽  
Author(s):  
Jishi Wang ◽  
Tianjin Chen ◽  
Weixing Zhang ◽  
Yan Zhao ◽  
Shuming Yang ◽  
...  
Keyword(s):  
Geographical Origin ◽  
Isotopic Analyses ◽  
Stable Isotopic

scholarly journals Analysis of causes of the end of service life of a spray polyurethane foam and polyurea roof

2020 ◽  
Vol 172 ◽  
pp. 15002
Author(s):  
Targo Kalamees ◽  
Simo Ilomets ◽  
Mattias Põldaru ◽  
Paul Klõseiko ◽  
Urve Kallavus ◽  
...  
Keyword(s):  
Service Life ◽  
Polyurethane Foam ◽  
Field Measurements ◽  
High Water ◽  
Climatic Conditions ◽  
Water Vapour Pressure ◽  
Hygrothermal Performance ◽  
Durability Prediction ◽  
Humidity Measurements ◽  
Term Performance

Spray polyurethane foam (SPF) roofs are widely used in North America. Much fewer usage examples and experience can be found in Northern European cold climatic conditions. This study analyses hygrothermal performance and the reasons for the roof’s degradation and end of service life of an SPF and polyurea roof. The service life of the roof is over and major reconstruction is needed eight year after construction. The current study uses field measurements included onsite temperature and humidity measurements and extensive surveying, the roof was opened from several locations and test samples were taken for laboratory tests. The influence of UV radiation on the loss of adhesion was tested. Solar radiation quickly degraded the top surface of the in-situ sprayed polyurethane foam insulation causing a weak connection between the foam layers. Due to mechanically damaged and UV degraded polyurea roofing, water has leaked into the SPF. The water inside or below the foam evaporated during sunny days and broke the adhesion of different foam layers. Larger foam blisters were observed on the upper part of the insulation caused by high water vapour pressure. This is considered the most realistic cause of separation of the SPF layers. The analyse of hygrothermal performance, service life, and durability prediction should be included into the design process, especially for structures with small or without long term performance experience.

Investigating the permeability of fractured rock masses and the origin of water in a mine tunnel in Shandong Province, China

2015 ◽  
Vol 72 (11) ◽  
pp. 2006-2017 ◽  
Author(s):  
Jie Guo ◽  
Haijun Zhao ◽  
Fengshan Ma ◽  
Kepeng Li ◽  
Chunhu Zhao
Keyword(s):  
Isotope Composition ◽  
Fractured Rock ◽  
Atmospheric Precipitation ◽  
Seepage Water ◽  
Rock Masses ◽  
Saline Groundwater ◽  
Isotopic Analyses ◽  
Stable Isotopic ◽  
Fractured Rock Masses ◽  
Different Sources

The coastal Sanshandao mine is threatened by the overlying Quaternary water and seawater. Following an introduction to the geology and hydrogeological conditions in the mine area, a detailed hydrogeological survey and sampling were conducted and hydrochemical and stable isotopic (δ2H and δ18O) tests on various waters were carried out to characterize the origin of water in the mine tunnels. Investigation and statistical analysis indicated that the northwest-trending fractures with large dip angles and long trace lengths are well developed in the northeast compared with those in the southwest of the mine. The permeability coefficients of the rock masses are in the range 4.19 × 10−8–2.25 × 10−5 m/s, indicating that the fractured rock masses have generally low permeability. The seepage water had higher values of EC, total dissolved solids, and concentrations of most elements than the seawater and saline groundwater. Besides, the isotope composition of the waters indicated that the seepage water was more isotopically enriched than seawater but less than brine. The proportions of the three different sources were calculated based on hydrochemical and isotopic analyses. Overall, the mine water was composed of 72% seawater, 14.8% brine, and 13.2% atmospheric precipitation, respectively. Therefore, some preventive measures are essential to avoid the probability of seawater inrush.

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