Soil Suspensions Research Articles

The effect of the antibiotic tetracycline hydrochloride on the biotransformation of urea when exposed to soil nitrifying strains

Introduction. The consequences of uncontrolled use of antibiotics in agriculture are an urgent problem of environmental hygiene. Tetracycline can enter the soil with the urine of domestic animals, inhibit the vital activity of soil bacterial strains and inhibit the processes of enzymatic hydrolysis of urea (carbamide), disrupting the global nitrogen cycle in nature. The lack of both quantitative and qualitative criteria for assessing this influence determined the relevance of the research. Materials and methods. The studies were carried out using the “Stayer” chromatographic system with cationic and anionic separating columns and exclusive analysis methods developed by the authors. When modelling solutions of heavy metals, an atomic absorption spectrometer MGA - 915MD with ETA was used. The objects of research were model solutions of carbamide with different content of inhibiting substances. As a source of urease and strains of Nitrobacter and Nitrosomonas, sod-podzolic soil from the Educational and Experimental Soil-Ecological Center “Chashnikovo” of Lomonosov Moscow State University was used. Results. An improved, more rapid chromatographic method for the analysis of urea in water is proposed compared to the method described by the authors earlier. The inhibitory effect of the antibiotic tetracycline hydrochloride on the process of biotransformation of nitrite into nitrate caused by Nitrobacter strains has been shown. No significant effect of the antibiotic on the biotransformation of urea into ammonium and ammonium into nitrite under the action of Nitrosomonas strains has been established. Limitations. The studies were carried out on the model of water systems, which included an aqueous phase containing different concentrations of the antibiotic, soil suspension, urea, heavy metal ions at a temperature of t = 30 ○C, pH ~ 6.5. The influence of salt background, pH, and temperature on biotransformation has not been studied, which could, without changing the overall picture, reveal nuances in the kinetics of the main processes. Conclusion. Studies have shown the absence of the effect of the antibiotic tetracycline hydrochloride on the kinetics of the decomposition of urea to ammonium and carbon dioxide due to urease enzymatic activity; there is no effect of the antibiotic on the oxidation of ammonium to nitrites by Nitrosomonas strains. It was found: selective inhibitory effect of an antibiotic during the oxidation of nitrite to nitrate, due to Nitrobacter strains; inhibition of biotransformation processes by chromium ions along the entire chain of transformations from urea to nitrate; and the inhibitory effect of excess oxygen on the totality of biotransformation processes during air bubbling through the aqueous phase.

Effect of Organic Matter And Soil Suspension on Clogging Drip Emitters under Application Two Different Water Qualities

       One of the most critical variables affecting the performance of drip irrigation systems is emitter clogging, which occurs quickly as a result of irrigation systems operating under insufficient pressure or due to poor water quality, not only affecting water distribution uniformity but also results in insufficient irrigation. To investigate the clogging potential of the drippers, two types of water quality were tested. Using local materials organic matter and soil suspension account for more than 47 percent of the clay content was applied with water. The tests identified the clogging severity of emitters with organic matter application for both water qualities Sumael (LSI) and Bazalan (LSII) respectively. In general, clogging ratios developed with time for both water qualities, the most distinct was organic matter application that reduced the discharge rate to 15.561% for Sumael water (LSI) corresponding to Bazalan water (LSII) was 38.002%. The flow rate of the drippers was also affected by the soil suspension particles. The percentages found in the Bazalan water was 5.62%, which was close to 5.575% in the Sumael water.

IMPROVEMENT OF TECHNOLOGY OF OBTAINING HIGH QUALITY OF ORGANIC FERTILIZERS WITH THE USE OF ASSOCIATED LAYER WATER AND PROBIOTICS

At the current level of development of agricultural production there are facts of environmental degradation due to the use of agrochemicals. The introduction of scientifically sound ecological technology of agriculture, which is based on the system of ecological safety of the environment and human health, can prevent possible negative effects. To ensure the sustainable development of modern agricultural production and the use of chemicals in limited quantities, there is a problem of their partial replacement by alternative low-cost measures based on natural processes of self-renewal. The aim of our studies was to determinate the effectiveness of obtaining high-quality organic fertilizers using associated water (SPV) and probiotic preparations that accord the requirements of environmentally friendly resource-saving technologies for growing crops. Ecological and trophic groups of soil microorganisms were determined by seeding certain dilutions of soil suspensions. The results of experiments show positive changes in quality and phytosanitary state of organic manure during three months of combined use of SPV (150 l t) and probiotics (100 l/t). The results of bacteriological research show that the level of pathogenic microorganisms decreased by 98-100% after 3 months of composting with native and 10% probiotic solution. Salmonella and Escherichia coli pathogens have not been identified. The cleaning efficiency was lower at 1% and 0.1% probiotic solution. According to mycological research the total number of fungi was 206.9 thousand/g, by 27% more than the control sample. The content of pathogenic fungi decreased by 88% compared to control. It was found that SPV and probiotics changes the chemical composition of manure. Although SPV does not contain large amount of essential mineral nutrients, but SPV are a valuable natural source of microelements that have a positive effect on the crops growth. In particular, the content of potassium in manure increased by 20.8%, phosphorus - by 41.8%, total nitrogen - by 45.8%, organic matter - by 10%. Thus, the integrated use of SPV and probiotics can destroy ruderal vegetation, reduce the germination of weed seeds, improve the quality of manure by enriching it with microelements, disinfect manure from pathogenic microorganisms and fungi. All these advantages make it possible to obtain high-quality organic fertilizer that allows you to optimize the soil nutrient regime. Research results show that the use of SPV and probiotics contribute to increase biological activity in the top soil layer, which determines the specific conditions of transformation of organic matter and productivity of agrobiocenosis. The proportion of microorganisms in the microbial cenosis with SPV 1200 l/ha and probiotics 100 l/ha is 19.2 ± 0.90 million (number of cells in 1 gram of completely dry soil), which is much higher than control (5.9 ± 0.21 million). Using SPV 1200 l/ha and probiotics 100 l/ha stimulates the growth and development of microscopic fungi and cellulose-destroying microorganisms involved in the decomposition of crop residues. There is an increase in the number of oligonitrophilic microorganisms that complete the mineralization of organic residues.

Особливості формування мікробного ценозу сірого лісового ґрунту за різних систем удобрення в агроценозі пшениці озимої

Goal. To study the formation of the number, structure, and qualitative composition of the microbial biome of gray forest soil in the cultivation of winter wheat under different fertilizer systems. Methods. The number of microorganisms of the main physiological groups was determined by the method of microbiological sowing of soil suspension on nutrient media. The structure and qualitative composition of soil microbiota were studied by generally accepted methods for morphological and cultural properties. The diversity of soil microbial complexes was assessed by the Shannon and Simpson ecological indices. Results. The number of microorganisms of different physiological groups varied depending on the fertilizer system (from 0.9 to 27.5 million CFU/g of soil). Application of mineral fertilizers in the dose of N100P60K100 caused a decrease in the number of microorganisms of all physiological groups compared to other fertilizer systems by 1.1 – 3.5 times. With the application of organomineral bioactive fertilizers (OMBF), cattle manure, and the combined use of cattle manure with mineral fertilizers at a dose of NN100P60K100, the number of microorganisms increased by 3.5 times. It was found that the microbial soil biome was differentiated by the number of detected morphotypes (bacteria — 35 – 46, micromycetes — 16 – 20, actinomycetes — 20 – 25) and the structure of their distribution (0.62 – 16.36%). The greatest diversity of bacteria, micromycetes, and actinomycetes (according to the Shannon and Simpson indices) was found for the introduction of cattle manure, the least — for mineral fertilizers (bacteria and actinomycetes), and the introduction of OMBF (micromycetes). The bacterial microbiota was characterized by the greatest species richness. Conclusions. The use of different fertilizer systems in the winter wheat agrocoenosis significantly affects the formation of microbial coenosis in the arable layer of gray forest soil, which is manifested in the differentiation of quantitative composition, structure, and diversity of microorganisms and redistribution of functional activity of microbial soil.

Prediction of movement of a large boulder in the channel of the mountain stream

As it is known, according to the type of formation, density, and fractional composition, debris flow is divided into two dynamic categories – cohesive (turbulent) and adhesive (hyper-concentrated, structural). Cohesive debris flows, the contents of which are represented in water as a soil suspension, obey the general laws of hydromechanics. Adhesive debris flow is not characterized by turbulent interchange, which is caused by saturation of the flow with fine fractions and adhesive water. Since, in certain sections of the transit zone of the flow, there are such changes in morphometric characteristics that are often not subject to assessment; the analytical solution of hydraulic problems of debris flows does not lose its relevance and is the object of research of many researchers. According to the above mentioned the article deals with the problem of the rectilinear motion of a boulder in the streambed with a positive bottom slope under the influence of water flow and gravity of a boulder. We obtained the equation for calculation of the average velocity of the water flow in order to transport a large boulder, which is partially submerged in the stream.

Photodegradation of Decabrominated Diphenyl Ether in Soil Suspensions: Kinetics, Mechanisms and Intermediates

Pollution by polybrominated diphenyl ethers (PBDEs) is a major concern due to their bioaccumulation, persistence, and carcinogenicity. This study aimed to investigate the decabrominated diphenyl ether (BDE-209) photodegradation in soil suspensions. The results indicate BDE-209 can degrade in soil suspensions and its degradation follows pseudo-first-order kinetics. The light sources and intensity effects were studied and the photodegradation rates were 500 W Mercury Lamp > 300 W Mercury Lamp > 500 W Xenon Lamp > 300 W Xenon Lamp, which indicates UV light is the main reason for BDE-209 degradation. Soil particle inhibits BDE-209 photodegradation due to the light-shielding effect. BDE-209 photodegradation rates increased from 0.055 to 0.071 h−1 with pH value increasing from 3.5 to 9.5. This may be because the products are more easily produced in higher pH soil suspensions. The presence of humic acid (HA) may inhibit BDE-209 photodegradation by photo-shielding. Fe3+ and Cu2+ have an adverse effect on BDE-209 photodegradation due to the photo competition. The •OH and 1O2 were detected in soil solutions. Analysis of the photoproducts of BDE-209 by gas chromatography mass spectrometry (GC-MS) and liquid chromatography time of flight mass spectrometry (LC-TOF-MS) showed that BDE-209 was mainly debrominated to the lower-brominated BDEs and the reactive oxygen radicals may not lead to BDE-209 degradation.

Magnetic enzyme-mimetic minerals with peroxidase-like activity can contribute to measured soil peroxidase activity

Magnetically responsive minerals were isolated from soil samples using a strong permanent magnet. The isolated materials exhibited peroxidase-like activity using N,N-diethyl-p-phenylenediamine sulfate salt as a substrate. Autoclaving and hot air treatment at 200 °C did not substantially decreased the enzyme-like activity; on the contrary thermal treatment many times caused an increase of peroxidase-like activity. Peroxidase activity measured in soil suspensions is thus due to both the enzymes (peroxidases) of microbial, plant and animal origin, and the inorganic peroxidase-mimetic minerals. We define a new research area called “soil nanozymology” devoted to study of soil-related nanozymes and other enzyme-mimetic materials.

Are enzymes transported in soils by water fluxes?

Transport of extracellular hydrolytic enzymes in soils has always been a subject of doubt. The considerations against its importance are that (i) enzymes benefit their producers the most when they remain in close proximity; and (ii) enzymes are large molecules with low mobility due to high affinity to fine soil particles and organic matter. However, soil mineral colloids (SMC), to which extracellular enzymes also have an affinity and which are known to facilitate transport of a broad variety of chemicals and microorganisms in soils, can serve as vehicles for enzyme transport as well. Since current literature lacks information on enzyme transport in soils, our goal was to determine whether enzymes are transported and, if so, whether they are transported in a free- or in a colloid-associated form. We conducted column transport experiments with four hydrolytic enzymes, namely, β-glucosidase, acid-phosphatase, cellobiohydrolase, and xylosidase, in soils with contrasting textures. The eluents containing enzymes were applied on top of soil columns, while enzyme activities, SMC, and electrical conductivity were measured in the effluents from the columns. Our results provided evidence of joint enzyme transport with soil colloids. The enzymes associated with the coarse SMC (1 μm < Ø) contributed 52–88% of the total enzyme activity in the effluents. The remaining enzyme activity was attributed to the enzymes associated with organic colloids, fine SMC (Ø < 1 μm) and free enzymes in solution. This study suggested a dual effect of ionic strength in the soil suspension on enzyme activity and their release from soils with soil colloids.

Effect of Treatment Compositions on the Plasticity of Tropical Red Soil Treated with Bacillus Coagulans

The study evaluated the effect of four treatment compositions on the plasticity of tropical red soil (Lateritic soil) admixed with Bacillus coagulans (B. coagulans). Samples for Atterberg limits test were prepared using four treatment compositional variables. They include 25% B. coagulans suspension and 75% cementation reagent, (25%B /75%C); 50% B. coagulans suspension and 50% cementation reagent (50% B /50%C); 75% B. coagulans suspension and 25% cementation reagent, (75%B /25% C) with the above three being in equivalent volumes of the corresponding liquid limit(LL) and 50% of the optimum moisture content (OMC) of compaction, to be both B. coagulans suspension and cementation reagent (i.e. 50% OMC B /50%OMC C) of the natural soil. Results showed that the LL for; 25%B /75% C, 50% B /50% C and 75% B /25%C generally increased from 0 up to peak values at 1.8 x 109 cells/ml and then declined at 2.4 x 109 cells/ml. In the case of samples treated with 50% OMC B/50% OMC C, the LL initially decreased from 0 up to 6.0 x 108 cells/ml and thereafter increased significantly. Plastic limit (PL), Plasticity index (PI) and Linear shrinkage (LS), recorded improvement. Regression analysis for the best treatment composition (i.e 75%B /25%C) has regression coefficient of 91.8%. Based on the four treatment compositions considered, 75%B/25%C enhanced the soil workability significantly and is suggested for geotechnical engineering applications such as road pavements that are lightly trafficked.

Transferability between soil organic matter measurement methods for database harmonization

Soil organic matter (SOM) is one of the most important soil-forming factors and complex with a chemical composition not fully known. The amount of SOM traditionally is estimated by stoichiometric determination of carbon dioxide (CO2) released from oxidation reaction with a chromium mixture, hence the term soil organic carbon (SOC). The two most common oxidation methods are Tyurin (T) and Walkley-Black (WB). However, the efficiency of organic carbon oxidation depends upon the conditions of the oxidation reduction (redox) reaction (temperature, reagent concentration, oxidation time), which vary for both methods. The lack of consistent results from the oxidation methods has led to widely different conversion factors. Although the Tyurin’s method has been slowly removed from some laboratories, there still remains a large number of samples, especially from Eurasia, that have been measured by this method for more than a century and continue at the present time. The objective of this research was to develop equations or pedotransfer functions (ptf) for converting SOC determined by the Tyurin method to current and more widely used methods, such as WB and dry combustion (DC).A comparative analysis was performed for the assessment of soil organic carbon content obtained by Tyurin and Walkley-Black methods for ten quality control soil samples and 100 field soil samples. The selected soils differed in their genesis, geographical origin, and organic carbon content. SOC determined by dry combustion, providing a maximum oxidation of organic carbon, was used as a standard for comparing Tyurin and WB methods. The conversion factors from Corg by DC developed from equations (ptf) were 1.15 and 1.30 for WB and Tyurin methods. The SOM measurement error for both methods did not exceed 20%. The relationship between the absorption of calibration solutions and the mass of sucrose carbon or the equivalent amount of iron (II) for the entire OC range in this study was very strong (r = 0.99). The values of the calibration function coefficients (A0, K) of the calibration functions A = A0 + Km (OC) for both methods, did not depend upon the nature of the reducing agent. The relative error of the K coefficients when using two reducing agents (Mohr’s salt or sucrose) was not more than δ2 ≤ 2.5%. Soil samples prepared using the Tyurin method experienced additional dispersion compared to the Walkley-Black method, which caused higher values in the measurement of SOC even after centrifugation of soil suspensions. The mean SOC measured value by the Tyurin method combined with 48 h settling time was comparable with the mean SOC measured by dry combustion.The established coefficients ensure that the results are transferable and consistent with the standard method. The results from this study facilitate the integration of the accumulated data that are analyzed by different methods across the Eurasian countries into one comprehensive database that could be incorporated into the global network for monitoring soil quality and carbon stocks

Increasing ionic strength and valency of cations enhance sorption through hydrophobic interactions of PFAS with soil surfaces

The effect of soluble cations on sorption in soils of a range of anionic PFAS is not well studied. We investigated the role of three common cations (Na+, Ca2+, and Mg2+) at varying solution concentrations on the sorption coefficients (Kd) of 18 anionic PFAS in two contrasting soils. The effective charge of the soil suspension (Zeta potential) became less negative as the concentration of these cations increased in the soil solutions. Perfluorinated compounds showed greater sorption than polyfluorinated compounds, with sulfonates of comparable chain lengths showing higher sorption than the carboxylates. We observed that the Kd values of several PFAS in the two soils were positively correlated with the concentration of cations in solution, especially in the presence of polyvalent cations (Ca2+and Mg2+). The changes in sorption with cation concentration were more prominent for long-chain PFAS, with C > 10 PFAS being completely removed from solution at higher cation concentrations. The emerging PFAS (replacement compounds GenX and ADONA) showed negligible or little sorption (Kd < 0.6 L/kg). While several mechanisms contribute towards sorption of PFAS in the presence of cations, we conclude that the primary effect of cations is through screening of negative charges on head groups of PFAS and reorientation of molecules at the interface between organic matter surfaces and soil solution as well as charge neutralisation at soil solid surface. Screening of negative charges allows for greater hydrophobic interaction between hydrophobic tails of PFAS and soil surfaces resulting in greater sorption. Increasing cation concentrations in soil solutions could thus reduce mobility of PFAS through a soil profile.

Isolation of rare Genera of actinomycetes — antibiotic producers from soils using Aloe Arborescens juice

The search for new antibiotics is an urgent problem due to the spread of resistance to existing antibacterial drugs in pathogenic microorganisms. Actinomycetes are producers of a large number of antibiotics used in medicine. Most antibiotics are isolated from actinomycetes of the Streptomyces genus, while rare genera of actinomycetes can be the producers of new antibiotics.The aim of the study is to investigate the effect of the biological substances complex present in aloe juice on the growth stimulation of rare genera of actinomycetes.Material and methods. Objects: samples of sod-podzolic soil and chernozem. The standard method of sowing soil suspensions on oat agar and Gause medium No. 2 was used to isolate actinomycetes. Chemotaxonomic properties were determined using the methods of ascending thin-layer chromatography on a cellulose layer. The generic identity of cultures was determined using Bergey’s manual and materials comparing the composition of cell walls of actinobacteria. DNA PCR with standard 27f and 1492r primers, as well as Sanger sequencing, were performed to study genosystematic features. Antibiotic activity was determined against the test microorganisms: Staphylococcus aureus ИНА 00985 (FDA 209P), Staphylococcus aureus ИНА 00761 (MRSA), Staphylococcus aureus ИНА 00762 (УФ- 2), Micrococcus luteus ATCC 9341, Bacillus subtilis ATCC 6633, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Saccharomyces cerevisiae ИНА 01042.Results. A total of 527 actinomycete cultures were isolated from samples of sod-podzolic soil and chernozem with the addition of aloe juice; their phylogenetic position was determined. The dominant actinomycetes in the studied soil samples are the representatives of the genus Streptomyces. Bacteria of the genus Micromonospora take the second place by the number of isolated cultures. Rare genera of actinomycetes have also been identified: Nonomuraea, Streptosporangium, Nocardia, Actinomadura, Actinocorallia, Pseudonocardia, Amycolatopsis, Saccharomonospora, Saccharopolyspora, Promicromonospora, Kribbella. It was determined that the isolated cultures possess antibiotic activity against test microorganisms.Conclusion. It is advisable to use aloe juice after subjecting the leaves to biostimulation to isolate actinomycetes from the soil and identify their biodiversity.

Soil Invertebrates Generate Microplastics From Polystyrene Foam Debris

To fully understand microplastics' impact on soil ecosystems, one must recognize soil organisms as not just passively enduring their negative effects, but potentially contributing to microplastics' formation, distribution, and dynamics in soil. We investigated the ability of four soil invertebrates, the cricket Gryllodes sigillatus Walker (Orthoptera: Gryllidae), the isopod Oniscus asellus L. (Isopoda: Oniscidae), larvae of the beetle Zophobas morio Fabricius (Coleoptera: Tenebrionidae), and the snail Cornu aspersum Müller (Stylommatophora: Helicidae) to fragment macroscopic pieces of weathered or pristine polystyrene (PS) foam. We placed invertebrates into arenas with single PS foam pieces for 24 h, then collected and assessed the microplastic content of each invertebrate's fecal material, its cadaver, and the sand substrate of its arena via hydrogen peroxide digestion, filtration, and fluorescent staining. All taxa excreted PS particles, though snails only to a tiny extent. Beetle larvae produced significantly more microplastics than snails, and crickets and isopods fragmented the weathered PS foam pieces more than the pristine pieces, which they left untouched. A follow-up experiment with pristine PS foam assessed the effect of different treatments mimicking exposure to the elements on fragmentation by isopods. PS foam pieces soaked in a soil suspension were significantly more fragmented than untreated pieces or pieces exposed to UV light alone. These findings indicate that soil invertebrates may represent a source of microplastics to the environment in places polluted with PS foam trash, and that the condition of macroplastic debris likely affects its palatability to these organisms.

Evaluation of Disease Suppressiveness of Soils in Croplands by Co-Cultivation of Pathogenic Fusarium oxysporum and Indigenous Soil Microorganisms.

An evaluation of suppressiveness against soil-borne diseases is important for their control. We herein assessed disease suppression against F. oxysporum f. sp. spinaciae using the Fusarium co-cultivation method in 75 soils collected from croplands around the country. The suppressive effects of soil microbes against F. oxysporum growth were examined by simultaneously culturing soil suspensions and F. oxysporum f. sp. spinaciae on a culture medium. The growth degree of F. oxysporum on the medium varied among the 75 soils tested, and 14 soils showing different degrees of growth were selected to investigate the incidence of spinach wilt by cultivating spinach inoculated with the pathogenic F. oxysporum strain. A correlation (r=0.831, P<0.001) was observed between the disease incidence of spinach wilt and the growth degree of F. oxysporum using the co-cultivation method in the 14 selected soils. No correlations were noted between chemical and biological parameters (including pH and the population density of microbes, except for the growth degree of F. oxysporum) and the growth degree of F. oxysporum and incidence of spinach wilt, indicating that it was not possible to predict the degree of growth or disease incidence based on specific chemical and biological characteristics or their combination. The present results suggest that an evaluation of the growth degree of F. oxysporum by the Fusarium co-cultivation will be useful for diagnosing the disease suppressiveness of soil against pathogenic F. oxysporum in croplands.

Microbial Degradation of Phenols by “Bacillus Brevis”

Industrial wastewater containing phenols causes significant environmental and ecological problems. Various methods such as chlorination, flocculation, adsorption etc. have been used for the degradation of phenol. But microbial degradation methods have proved to be the most effective and economical approach for the mineralization of toxic chemicals. A soil microbial strain Bacillus brevis, capable of utilizing phenol as a sole carbon source was isolated from the phenol bearing soil suspension of Briquetting and Carbonization Plant of NeyveliLignite Corporation Limited, (Tamil Nadu) and tested for its capacity to grow and degrade phenol. Based on it’s morphological, physiological and biochemical characteristics, the organism was found to be a Gram-positive, motile, mesophilic and rod-shaped endospore bacterium. The results indicate that the growth of the organism decreases at very high concentration of phenol. The efficiency of the organism in the degradation of substituted phenols such as o &amp; p chlorophenols and o &amp; p nitrophenols were compared and discussed. The degradation was highly efficient in the pH range 8 – 10. The biocatalyst obtained by immobilizing the Bacillus brevis cells on alginate beads and lignite carbon are more effective in degrading phenols.

A novel approach to evaluate the clogging resistance of pervious concrete

Pervious concrete is an important material for permeable pavement, while the clogging phenomenon is deleterious to the service performance of the pervious concrete pavement. In this paper, the pervious concrete is proportioned by introducing a parameter of filling ratio, and the influences of filling ratio and W/C ratio on compressive strength and permeability of pervious concrete are investigated. A novel method using saturated slurry (soil suspension) as clogging media is proposed to evaluate the clogging resistance of pervious concrete. The pore characteristics are analyzed by the image processing to interpret the clogging phenomenon. The results indicate that the filling ratio is an essential parameter in the mix design of pervious concrete, while the only decrease of W/C is not always effective to prepare high performance pervious concrete. The proposed method could evaluate the clogging risk with clogging cycles for pervious concrete with different pore structures. According to image processing analysis, large pores are beneficial to the permeability, but on the contrary, excessive large pores would reduce the permeability due to the increase of pore tortuosity. More importantly, except for porosity and tortuosity, the pore size distribution needs to be sufficiently considered to design an unclogged pervious concrete.

Larvicidal Potential of Conidia Suspension of Aspergillus flavus against Anopheles Mosquitoes

Abstract: Aim: This study was aimed at investigating the larvicidal potential of the conidia suspension of Aspergillus flavus against Anopheles mosquitoes. Method: Aspergillus flavus was isolated from soil using soil suspension procedures and was identified using morphological characteristics. Bioassay was performed to determine the efficacy of Aspergillus flavus conidial suspension against early 4th instar larvae of Anopheles mosquito using WHO-2005 protocol with slight modifications. Results: Four different concentration of conidial suspension; 3.3×106, 3.3×105, 3.3×104 and 3.3×103 conidia/ml were tested, and the results show that; mortality increases with increase in conidial concentration and exposure time. Conclusion: These results indicated that Aspergillis flavus conidia suspension are pathogenic to immature stage of Anopheles mosquito and could be suggested as a biological control for mosquito management.

Soil-pH and cement influence the weathering kinetics of chrysotile asbestos in soils and its hydroxyl radical yield

Chrysotile asbestos is a toxic and carcinogenic mineral that has been used in a variety of industrial and consumer applications. Much of the fiber- and cement-containing asbestos waste has ended up in terrestrial environments. Chrysotile weathering in soils and the potential for natural attenuation have, however, hardly been examined yet. Here we explored how soil properties influence the dissolution rate of chrysotile, the release of the carcinogenic metals chromium and nickel, and the hydroxyl radical (HO•) generation by chrysotile fibers. Chrysotile dissolution rates in soil suspensions decreased with increasing soil-pH and were lower than reported rates in soil-free systems. Dissolved organic carbon did not markedly accelerate dissolution at circumneutral pH, whereas cement mixed with soil inhibited dissolution because of its alkalinity. The HO•-yield of incubated fibers in non-amended soils eventually decreased by 60–75%. The decline was fastest in an acidic podzol soil, yet was followed by a small rebound. Cement amendment induced the largest HO•-yield reduction (∼90%), presumably due to surface coating of the fibers. Overall, this work demonstrates that the potential for natural attenuation of chrysotile asbestos in soils critically depends on soil chemical parameters and the presence of cement in association with the fibers.

Ecological condition of the adjacent territory of pig farms of different capacity and technologies of pork production

Investigate the differences between chemical and microbiological parameters of the topsoil and snow cover at different distances from the territories of pig farms of different capacity and different technologies of pork production. It has been carried out Soil sampling and soil chemical analysis in accordance with current state standards of Ukraine. Hydrochemical analysis of melt water was carried out according to the methods of O. A. Alekin. Microbiological studies were performed by seeding the soil suspension and melt water on appropriate solid nutrient media. So, Soil research revealed a higher content of certain chemical elements and microorganisms in the immediate vicinity of farm areas compared to more distant distances. Thus, according to the chemical analysis of the soil near Farm 1 (number of livestock 1.5 thousand heads, seasonal tour technology of pork production is used) at a distance of 0 m there is a higher content of ammonium N, P2O5, K2O, Cu, Zn. Near Farm 2 (number of livestock 40.0 thousand heads, used flowshop technology of pork production) at a distance of 0 m there is a higher content of only N ammonium, Cu and Z. Microbiological analysis of soil was performed by the method of aggregate assessment of the presence of microorganisms using an integrated indicator. It was found that near Farm 1 at a distance of 250 m there is only a downward trend, and a significant decrease only at a distance of 500 m, and in Farm 2 - this figure is significantly reduced at a distance of 250 m. Hydrochemical studies of melted water of the snow cover adjacent to pig farms include a list of studied chemical components, the presence of which varies depending on the distance from the farm: nitrogen compounds related to nutrients and individual ions of mineral compounds - Na+ + K+, SO42 According to the studied chemical and microbiological indicators of the soil, it is established that the radius of harmful effects of the enterprise with seasonal tour technology of pork production is larger compared to the enterprise with flow-shop technology of pork production. According to the research of the melted water of the snow cover of the territory adjacent to the pig farms, a number of components have been identified that can be used as indicators that will characterize the harmful impact on the environment of pork enterprises. Key words: Pig farms, natural environment, topsoil, snow, chemical elements, microorganisms, pollutants.

Efficient separation performance of suspended soil and strontium from aqueous solution using magnetic flocculant

This study aimed at magnetically separating suspended soil and Sr2+ from a soil suspension using a magnetic flocculant (MNP/IF). MNP/IF was prepared using the electrostatic interaction between the magnetite particles and the inorganic flocculant (IF) based on CaCO3 and Na2SO4. By analyzing the physical properties of MNP/IF, it was confirmed that MNP/IF was successfully imparted with magnetism and had excellent adsorption capacity for Sr2+. The optimal MNP/IF dosage for the sedimentation of suspended soil was determined to be 0.3 g/g (mass ratio of flocculant to soil). Compared with raw IF, MNP/IF showed better flocculation performance to suspended soil for a shorter sedimentation time. The lower the pH, the more favorable the flocculation-sedimentation process of the suspended soil by MNP/IF, since Ca2+ and Mg2+, which are the most common strong flocculators, were further eluted from IF under acidic conditions. MNP/IF also showed excellent removal performance for Sr2+, exhibiting maximum Sr2+ adsorption capacities of 163.6 mg/g in the flocculation-sedimentation reaction of suspended soil. The Sr2+ adsorption process was consistent with the Langmuir model and followed the pseudo-second-order kinetics. These results provide that MNP/IF can be used for the simultaneous removal of suspended soil particles and Sr2+ from a radioactive soil suspension.