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Heavy metal toxicity detection in phytoplankton by using neural network analysis of chlorophyll fluorescence induction

S.S. Khruschev, Т.V. Drozdenko, Т.Yu. Plyusnina, I.V. Тimofeev, D.A. Todorenko, E.I. Tikhomirova, Т.К. Аntal

Section: Ecotoxicology

Application of artificial neural networks for identifying poorly formalized patterns in experimental become widespread nowadays. In the present work, we elaborated a prototype of a model for detection of water contamination with heavy metals. The model is a fully connected neural network (multilayer perceptron) designed by using the Python programming language and the TensorFlow software (Keras). It is intended for application in environmental monitoring of natural water bodies using chlorophyll fluorescence measurements which are considered as highly informative approach for probing photosynthetic activity in vivo and in situ. Fluorescence rise induced by application of a strong light pulse to the dark-adapted plant or algae (the OJIP transient) reflects a stepwise transition of the photosynthetic electron transport chain from the oxidized to the fully reduced state. To provide a quantitative analysis of the OJIP transient, a JIP test was introduced whose parameters describe energy fluxes through the photosynthetic electron transport chain. Our model uses OJIP transients and/or JIP-test parameters, measured in phytoplankton communities, as input data. As a result, it determines the probability of water pollution by heavy metals. In order to test the model, phytoplankton samples were taken from 9 water bodies of Pskov region and then treated with chromium and cadmium under laboratory conditions. For that, phytoplankton samples were exposed to cadmium and chromium salts (CdSO4 and K2Cr2O7) at two concentrations (20 and 50 μM) for three days, and OJIP curves were recorded and JIP-test parameters calculated at different stages of the experiment. In total, 419 curves were collected, and a whole dataset was analyzed. Results showed that accuracy of detecting the toxic effects of Cd2+ (after 2 or more hours of incubation) and Cr2O72– (after 9 or more hours of incubation) by the model achieved 90%. The highly accurate determination of the toxicity of heavy metals indicates a promising prospect for the application of machine learning technology in environmental monitoring.

Keywords: heavy metals, aquatic ecosystems, phytoplankton, environmental monitoring, neural networks, chlorophyll fluorescence, photosynthesis

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Article published in number 2 for 2021
DOI: 10.25750/1995-4301-2021-2-134-141

Improvement of fluorometric method for polycyclic aromatic hydrocarbons determination in environmental objects

O.A. Plotnikova

Section: Methodology and research methods. Models and forecasts

The selection of suitable pre-sample preparation and analysis methods for effective monitoring of polycyclic aromatic hydrocarbons (PAHs) is essential. An important task is to control the PAHs content in various media. These substances, even at low concentrations, can pose a threat to public health, can have carcinogenic, mutagenic and teratogenic effects on living organisms. A distinctive feature of PAHs molecules is the ability to absorb energy and luminescence under the influence of UV radiation. In this regard, spectroscopic methods are promising for the PAHs determination. The paper presents the characteristic absorption and fluorescence spectra of PAHs, and indicates their excitation and fluorescence wavelengths. An experimental study of the metrological characteristics of various spectroscopic methods has been carried out. The PAHs representative pyrene was determined by spectrophotometry and fluorimetry in solutions, as well as solid-phase fluorimetry with preliminary micellar and sorption concentration on a solid matrix. The use of aqueous micellar solutions of the nonionic surfactant Triton X–100 made it possible to enhance the analytical signals for the pyrene determination. The data obtained confirm the fact that the fluorescence method is characterized by a higher sensitivity than the method based on the registration of these substances’ absorption. The linear range of concentrations determined by the spectrophotometric method is more significant in comparison with the fluorometric methods and amounts to 14–10000 ng / ml. At the same time, the combination of preliminary micellar and sorption concentration with solid-phase fluorescence on a modified by surfactants viscose matrix made it possible to reduce the detection limit of pyrene to 0.8 ng / ml, which is especially important for the development of methods for controlling ecotoxicants contained in the environment in "trace" concentrations.

Keywords: polycyclic aromatic hydrocarbons (PAHs), spectroscopic methods, absorption spectrophotometry, fluorimetry, sorption concentration, solid-phase fluorescence

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Article published in number 2 for 2021
DOI: 10.25750/1995-4301-2021-2-044-048

Natural-climatic factors in ecological zoning of the city of Irkutsk

E.V. Maksyutova, L.B. Bashalkhanova, L.M. Korytny, A.A. Sorokovoi

Section: Monitoring of natural and anthropogenically disturbed areas

An analysis is made of the natural-climatic characteristics of the formation of the ecological status of the atmospheric air in the city of Irkutsk. It is found that its chronic pollution is associated with a long-term annual exceedance of MAC for 5 to 6 specially hazardous pollutants, and with a persistent presence of suspended substances (up to 2.4 MAC) and benzo(a)pyrene (up to 7.8 MAC). The main volume of pollutants emissions corresponds to a long-lasting heating season (mid-September‒mid-May). A zoning of the territory of the city was carried out according to the degree of the possible effect of topography and prevailing type of underlying surface (water, forest-park, and stone and wooden buildings) on air temperature in the atmospheric ground layer. The zone of strong influence includes three types of microclimate of lowlands, with the January temperature deviations from 1.9 to ‒3.6°C from the Irkutsk, Observatory base weather station. Stagnant phenomena in this zone can promote formation of intense air pollution of residential and recreational territories. In this case, topography is the leading factor for the spatial differentiation of air temperature. Because of a high activity of the air exchange, the summit surfaces experience a weak impact of the environmental factors. The zone of moderate impact on slopes and planate territories reflects the local characteristics of the underlying surface. The dominant influence of stone buildings and roads on air temperature is most clearly pronounced in the center of the city on the right bank of the Angara; on the left bank, it is smoothed out by the influence of forested areas. With distance from the center of the city, similar air temperatures are typical for the slopes of different gentleness and aspect. This occurs as a result of significant differences in heat exchange in the dominant types of underlying surface.

Keywords: atmospheric air condition, microclimate of the city, deviations of air temperature in January, types of underlying surface, zoning of the urban environment

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Article published in number 2 for 2021
DOI: 10.25750/1995-4301-2021-2-055-059

The stability assessment of the morphological and functional characteristics of rhizospheric strains of Bacillus subtilis using atomic force microscopy

M.N. Artamonova, N.I. Potaturkina-Nesterova, B.B. Kostishko

Section: Methodology and research methods. Models and forecasts

The important advantage of atomic force microscopy (AFM) is the low power requirements for the studied objects, which allows studying living cells without fixation and with high resolution. It was proposed to use AFM to determine the morphometric and elastic-mechanical characteristics of the marker specie Bacillus subtilis isolated from the rhizosphere of the Cucurbita pepo L. crop in different vegetative phase of plant development. These characteristics of the microorganism are indicators of their functional activity and resistance to the action of biotic and abiotic environmental factors. It was shown that some parameters (length, width and height, elastic modulus, and the root mean square roughness) of B. subtilis isolated at different phases of plant growth were stable. So, elastic modulus of the bacilli was equal to 5.9 ± 0.2 MPa in plant sprouting phase, 5.8 ± 0.1 MPa in the phase of budding, 6.0 ± 0.3 MPa in the phase of flowering 5.7 ± 0.3 MPa in the phase of fruiting of the plant. The indicator of the root mean square surface roughness was equal to 37.5 ± 0.6 nm in plant sprouting phase; 35.1 ± 4.6 nm in the phase of budding; 31.8 ± 2.8 nm in the phase of flowering and 40.0 ± 2.1 nm in the phase of fruiting of the plant. AFM study of the surface of B. subtilis cells revealed a change of the adhesion force of the studied strains. This indicator was equal to 32.0 ± 6.0 nN and 41.0 ± 8.0 nN in plant sprouting and budding phases respectively. And the adhesion force was increasing significantly in the flowering and fruiting phase in comparison to the first phases (73.0 ± 5.0 nN and 69.0 ± 3.0 nN, respectively; p <0.05). The use of atomic force microscopy technology has shown its effectiveness in studying of the stability of the morphometric and elastic-mechanical characteristics of B. subtilis, which are indicators of functional activity of the plant. It was suggested an approach to the development of a methodology for assessing and managing the quality of ecosystem components based on the use of a new information method for the study of marker biological objects.

Keywords: Bacillus subtilis, rhizospheric bacteria, bacterial-plant symbiosis, atomic force microscopy, morpho-functional properties of bacteria

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Article published in number 2 for 2021
DOI: 10.25750/1995-4301-2021-2-038-043

A method for assessing the productivity of marine areas by the integrated intensity of bioluminescence of the planktonic community

E.B. Mel’nikova, A.N. Serebrennikov, A.V. Melnikov

Section: Methodology and research methods. Models and forecasts

A method for the comparative assessment of the productivity of marine water areas based on an analysis of the vertical distribution of the glow intensity (bioluminescence) of planktonic communities is presented. In the coastal waters of Crimea, 5 regions were marked out, which differ in the vertical distribution of the intensity of bioluminescence, the total biomass, and the number of plankton communities. It is noted that planktonic communities that have a quick response to changes in the ecosystem can serve as an operational indicator of the effects of various environmental factors on it. Bioluminescence intensity measurements do not require laboratory processing of samples and are carried out in real time. A methodology for calculating the integral intensity of bioluminescence of hydrobionts (IIBH), which characterizes the total biomass, the number of aquatic organisms, and the biological productivity of water, is described. For selected areas, IIBH calculation was performed. A comparative assessment of the water productivity of the selected areas showed that the highest IIBH (an average of 37830 pW∙cm–2l–1) was observed on the southwestern shelf of Crimea. In the area of the Kerch Strait, IIBH was 1.24 times less than on the highly productive south-western shelf of Crimea. In the north-western deepwater part of the sea, stable stratification of the waters promoted the formation of two layers with a high concentration of hydrobionts located at depths of 8–14 m and 40–45 m. At the same time, IIBH of the upper layer was the smallest in the study area and was 8 times lower than the value on the south-western shelf of Crimea. The results obtained on the productivity of water areas and the total biomass of plankton communities serve as the basis for the development of measures for the rational use of natural resources.

Keywords: bioluminescence, phytoplankton community, vertical distribution, water productivity

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Article published in number 2 for 2021
DOI: 10.25750/1995-4301-2021-2-031-037

Zoobenthos of the Severnaya Dvina River delta

M.A. Studenova, I.I. Studenov, D.V. Chupov, A.S. Samodov

Section: Monitoring of natural and anthropogenically disturbed areas

Systematic studies of zoobenthos at the delta of the Severnaya Dvina river begun in 2012. This study contains the most complete information about the taxonomic composition of zoobenthos of the area, the number and frequency of taxons, the number and biomass of each of the taxa. Twenty taxons belonging to 6 types and 11 classes of invertebrates were found in zoobenthos during the whole period of research (2012-2018). The average number of taxons per 1 station during the entire research period was 9, ranging from 5 in the Korabel’ny arm to 16 in the Murmansk arm. Oligochaetes, bivalvia, and chironomidae larvae were found in samples at all stations each year. Isopods, dayflies larvae and beetle larvae were found with lowest occurrence rate. Average value of Shannon ’s zoobenthos index at the delta of the Severnaya Dvina river was 1.21, varying from 0.70 (Maimaxa and Kuznechikha branches) to 1.84 (Murmansk arm). The number of invertebrates over the years varied very widely - from 640 spec/m2 (Korabel’ny arm, 2018) up to 16573 spec/m2 (Murmansk arm, 2014), averaging 5704 spec /m2. Oligochaetes and сhironomidae larvaes were the most numerous. The biomass of invertebrates at the delta of the Severnaya Dvina river varied very widely - from 0.29 g/m2 (Korabel’ny arm, 2017) to 25.3 g/m2 (Murmansk arm, 2014), averaging 6207 mg/m2 for all observation years. The base of biomass was formed by Oligochaetes, their participation in the formation of total biomass reached 94.6%. An average oligochet index was 57.8%. The water condition of the delta of the Severnaya Dvina river was classified as moderately contaminated, according to the values of the oligochet index.

Keywords: Severnaya Dvina river, zoobenthos, taxonomic composition, number, biomass

Article published in number 2 for 2021
DOI: 10.25750/1995-4301-2021-2-060-065

Effect of rhizospheric oil-degrading bacteria on the biological state of oil-polluted soil

M.S. Tretyakova, L.A. Belovezhets, L.G. Sokolova, S.Yu. Zorina, Yu.A. Markova

Section: Remediation and rehabilitation

Environmental pollution with oil and oil products is a serious issue faced both by Russia and by the whole world. Currently, the use of microbiological preparations, which include indigenous microorganisms adapted to climatic and environmental conditions of a particular region, is an effective way to remediate oil-polluted soils. The use of microorganisms isolated from plant rhizosphere is promising for soil bioremediation due to their high biotechnological potential. The paper presents the results of model experiments on the influence of strains of oil-degrading microorganisms (Rhodococcus erytropolis 108, Acinetobacter guillouiae 112, Acinetobacter guillouiae 114) isolated from wheatgrass rhizosphere and their consortium on the purification of oil-polluted soil. The indicators of soil phytotoxicity, change in its enzymatic and respiratory activity. After 60 days of the experiment, the oil loss in oil-polluted soil with the introduction of the studied strains was shown to increase by 19-24% relative to the control and amount to 62-68% of its initial content. The enzymatic and respiratory activity of the soil increased against the background of oil destruction by the microorganisms. Treatment of oil-polluted soil with the strains of oil-degrading bacteria contributed to an increase in its phytotoxicity in the early stages of radish (Raphanus sativus) ontogeny. This was especially characteristic of the A. guillouiae 112 strain. The soil inoculated with R. erytropolis 108 had the least phytotoxicity throughout the experiment. For the first time, the obtained rhizospheric strains of the genera Rhodococcus and Acinetobacter were shown to accelerate the process of purifying the soil from oil and be able to be used for bioremediation of oil-polluted soils.

Keywords: rhizospheric oil-degrading microorganisms, oil-polluted soil, soil biological properties, oil biodegradation.

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Article published in number 2 for 2021
DOI: 10.25750/1995-4301-2021-2-156-162

Features of transformation of old oil pollution in the soils of the Arctic zone of Yakutia

Yu.S. Glyaznetsova

Section: Chemistry of natural environments and objects

In the Arctic zone of Yakutia, ecological and analytical studies have been carried out to study the chemical composition of the oil-contaminated soils of the tank farm. The row of informative analytical indicators was used to characterize the composition of oil pollution and assess the features of its biodegradation processes in permafrost soils. The features of the chemical composition of oil pollution in soil samples with a long-term contamination are revealed and are taken into account at developing methods for cleaning soils from "old" oil pollution. An experiment on the biological treatment of soils with a biological product based on indigenous hydrocarbon-oxidizing microorganisms isolated from permofrost soils was conducted. The initial oil content was 34594 mg/kg. After 3 months of incubation of a biological product, along with a decrease in the residual oil content, the composition of pollution changed in the direction of increasing the content of resin-asphaltene components and decreasing − hydrocarbons. The proportion of oxygen-containing groups and bonds has significantly increased in the chemical structure of alcohol-benzene resin. In the composition of alkane hydrocarbons, a redistribution is established both within the homologous series and between different rows of homologues. The established increase in the ratio (Pr+Ph) / (nC17+nC18) in the row: oil (as a pollutant) → initial “old” pollution → altered pollution after 3 months of incubation of the biological product, indicates the destruction of n−alkanes nC17 and nC18, which are least resistant to biodegradation, and relative accumulation more stable isoprenoids of pristan and phytane. The degree of destruction of oil pollution reached 56.6%.

Keywords: transformation, old oil pollution, biodegradation, permafrost soils, asphaltenes and resins components

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Article published in number 2 for 2021
DOI: 10.25750/1995-4301-2021-2-089-094

Features of the allocation of high conservation values of type “Rare ecosystems and habitats” for certification of forests of the Kirov region

N.P. Savinykh, S.V. Shabalkina, O.N. Perestoronina

Section: Social ecology

One of the modern requirements of forest management is the conservation of biodiversity by identifying forests with high conservation value (HCV), especially rare ecosystems and habitats (HCV type 3). Based on the systemic and regional approaches, the methodology for determining HCV 3 has been improved and a system has been created in the Kirov region with the distribution of classes and levels. The class of Fir-spruce forests includes two levels – large-fern with the presence of nemoral elements and tall grasses; with the presence of rare and vulnerable species. The class of Pine forests are divided into sphagnum with the presence of rare and vulnerable species, lichen (with steppe elements) and heather. The Forest class with the participation of broad-leaved species has three levels – linden and multi-species forests in the subzones of the middle and southern taiga of the Kirov region, oak forests (including the subzone of mixed forests). The classes of Larch and Black alder forests, Old-aged aspens are not subdivided into levels. The composition of the stand, the age of the prevailing species of the stand, the species composition of the grass-shrub layer, the conservation value and the recommended conservation and forest management regimes each HCV 3 describes; necessary criteria for assessing forest management, monitoring and compliance of forestry activities with international standards are identified. The developed system is not final; it can be supplemented and expanded in connection with newly emerging data. The use of the proposed materials will ensure the conservation of biodiversity of production forests, compliance with the requirements of the National FSC Standard of the Russian Federation for forest management, and positioning of the Kirov region as a supplier of quality wood.

Keywords: high conservation value forests, biodiversity, rare species, rare community, ecosystem, forest management regimehigh conservation value, biodiversity, rare species, rare community, ecosystem, forest management regime

Article published in number 2 for 2021
DOI: 10.25750/1995-4301-2021-2-229-234

Pechora Sea polychaete worms: biodiversity and spatial distribution

S.Yu. Gagaev, S.G. Denisenko, A.V. Sikorsky, N.А. Strelkova, E.A. Frolova

Section: Population ecology

The modern taxonomic and geographical composition, trophic mode and spatial distribution of polychaete worms - one of the most important components of the bottom ecosystems of the Pechora Sea, is studied. This area characterized by the special abiotic conditions, a high level of biological production, a variety of biotopes and numerous populations of rare and protected species. According to the materials of the last expeditions in the Pechora sea, 198 taxa of polychaete worms were identified: 165 belonging to species, 113 genera, 34 families and 14 orders. Everywhere the species diversity of polychaetes and stress stability of their populations was high, with the exception of small areas, located near entrance to the Pechora and Khaypudir bays with amount of river runoff. The density of settlements widely varied from 26 to 7144 ind./m2. Density gradients are most pronounced in the south-eastern shallow part of the Pechora Sea and in a lesser extent in the north-western of region. The spatial distribution of polychaete biomass is also heteroge-neous, but varies much less in absolute terms from 0.7 to 387 g/m2. Four major groups represent the trophic mode of polychaete bioresources. More than half of the total biomass is created by surface detrivorous, a few less than a third - by subsurface detrivorous, 2% - by suspension feeders, and 10% - by carnivorous. The 80% of all polychaetes constituted only by six species, and the most significant of which are Spiochaetopterus typicus and Maldane sarsi. During the last 70 years the number ratio of species belonging to main biogeographic groups remains stable, although the taxonomic list is constantly increasing. The stable state of the of poly-chaete taxocene, playing the significant role in the bottom ecosystems, assumes the stable state of bot-tom biocenoses of the Pechora Sea in general.

Keywords: Polychaete worms, Pechora Sea, biodiversity, spatial distribution, biogeography, trophic mode

Article published in number 2 for 2021
DOI: 10.25750/1995-4301-2021-2-208-214

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