Dichromate Oxidation Research Articles

Validation Study on Spectrophotometric Measurement of Ethanol from Beer and Non-Alcoholic Beer Samples Distilled by Micro Steam Distillation Method

The method validation technique for determining the ethanol percentage (v/v) in beer and non-alcoholic beer is presented in this study. The underlying idea is to use the micro water vapor method to distill the ethanol from beer and then use the spectrophotometric method, which uses the oxidation of sodium dichromate to measure the amount of ethanol. The Harmonized Guidelines for Single-Laboratory Validation of Methods of Analysis were used to validate the analytical method that we provided. The following aspects of the method were assessed: precision, recovery, linearity, measuring range, detection and quantification limitations, method detection limit, and measurement uncertainty. The following were the limits of detection (LOD) and quantification values (LOQ), and the method detection limit (MDL): ethanol, 0.04%, 0.05%, and 0.15. For both repeatability and within-laboratory reproducibility, the relative standard deviation values were less than 2.36 and 4.12%, respectively. The spiked samples had recovery rates ranging from 97% to 102%. These findings fulfilled the minimal performance standards set forth in AOAC Official Methods of Analysis Appendix F: Guidelines for Standard Method Performance Requirements. As a result, the process can be used for the regular analysis of ethanol in the beer and non-alcoholic beer under study.

Agroecological assessment of spatial variability of carbon content in the conditions of disturbed sod-podzolic soils

Soil carbon is one of the main carbon pools of terrestrial ecosystems. The carbon of arable soils is the most labile. In this regard, rapid and accurate methods for determining soil carbon in different forms are of great interest to researchers. Therefore, in this paper we decided to conduct a comparative analysis of the results of organic carbon determination using the Walkley-Black method (colorimetric method), the Dumas dry combustion method (using the CN Vario El Cube analyzer)) and the remote method using the Valeeva approach (Valeeva, Aleksandrova, Koposov, 2016) according to the values of the red channel of the spectrum, on the images obtained using an RGB camera mounted on a DJI Phantom 4 drone. For laboratory analysis, 100 soil samples of the arable horizon were collected at regular grid points, georeferenced using RTK. The correlation between the Dumas dry combustion method and potassium dichromate oxidation was 0.24 (for n = 100, significant p=0.195), allowing comparison at the trend level. The highest correlation (R = 0.39 was observed between the data obtained using the Dumas method and the Valeeva-Alexandrova approach, indicating that it can be used to estimate soil carbon dynamics from RGB images. Correlation analysis showed relationships (R = 0.63) between total carbon and microrelief, which is reflected by the drone-derived digital elevation model.

A Rapid and Accurate Quantitative Analysis of Cellulose in the Rice Bran Layer Based on Near-Infrared Spectroscopy.

Cultivating rice varieties with lower cellulose content in the bran layer has the potential to enhance both the nutritional value and texture of brown rice. This study aims to establish a rapid and accurate method to quantify cellulose content in the bran layer utilizing near-infrared spectroscopy (NIRS), thereby providing a technical foundation for the selection, screening, and breeding of rice germplasm cultivars characterized by a low cellulose content in the bran layer. To ensure the accuracy of the NIR spectroscopic analysis, the potassium dichromate oxidation (PDO) method was improved and then used as a reference method. Using 141 samples of rice bran layer (rice bran without germ), near-infrared diffuse reflectance (NIRdr) spectra, near-infrared diffuse transmittance (NIRdt) spectra, and fusion spectra of NIRdr and NIRdt were used to establish cellulose quantitative analysis models, followed by a comparative evaluation of these models' predictive performance. Results indicate that the optimized PDO method demonstrates superior precision compared to the original PDO method. Upon examining the established models, their predictive capabilities were ranked in the following order: the fusion model outperforms the NIRdt model, which in turn surpasses the NIRdr model. Of all the fusion models developed, the model exhibiting the highest predictive accuracy utilized fusion spectra (NIRdr-NIRdt (1st der)) derived from preprocessed (first derivative) diffuse reflectance and transmittance spectra. This model achieved an external predictive R2p of 0.903 and an RMSEP of 0.213%. Using this specific model, the rice mutant O2 was successfully identified, which displayed a cellulose content in the bran layer of 3.28%, representing a 0.86% decrease compared to the wild type (W7). The utilization of NIRS enables quantitative analysis of the cellulose content within the rice bran layer, thereby providing essential technical support for the selection of rice varieties characterized by lower cellulose content in the bran layer.

Comparison of methods for determining organic carbon content of urban soils in Central Ohio

Reliable methods are key to quantify organic carbon in urban soils. Samples from across the Ohio State University campus were divided into two datasets (a) pH ≤ 7.5 and (b) pH ≥ 7.8. Organic carbon was assessed using multiple methods, including heated acid dichromate digestion (OCDichromate), loss-on-ignition (LOI) at 400 °C and 550 °C, a dry combustion method (OCTC), and an acid pre-treatment (OCacid). Mean organic C, in g kg−1, were OCTC (39.8), LOI550 (39.8), LOI400 (33.2), OCDichromate (31.8) for soils with pH ≤ 7.5. LOI400 and OCDichromate were more accurate than OCTC and LOI550. Mean organic C, in g kg−1, were LOI550 (23.6) > OCacid (20.2) ≥ LOI400 (17.9), OCDichromate (16.0) for soils with pH ≥ 7.8. Similar to pH ≤ 7.5 soils, LOI400 and OCDichromate methods were more accurate measures of OC. The two loss-on-ignition methods and the dichromate method were strongly correlated with each other (r = 0.91) however the two dry combustion methods were weakly correlated with the others (0.45 ≥ r ≤ 0.67). The dichromate oxidation proved to have the lowest variance of the methods tested (29.7 g2 kg−2). Paired t-tests found no significant differences between the loss-on-ignition 400° and the acid-pretreatment methods, and no significant differences between the dichromate and inorganic subtraction method (p < 0.05). Dichromate oxidation method should be implemented to measure soil organic carbon in urban soils that have carbonates present, especially dolomite. The dichromate oxidation method was found to be simple, rapid, and reliably determines SOC without the need to remove SIC.

Soil Organic Matter in Urban Areas of the Russian Arctic: A Review

Polar ecosystems are the most important storage and source of climatically active gases. Currently, natural biogeochemical processes of organic matter circulation in the soil-atmosphere system are disturbed in urban ecosystems of the cryolithozone. Urbanized ecosystems in the Arctic are extremely under-investigated in terms of their functions in regulating the cycle of climatically active gases. The role of urban soils and soil-like bodies in the sequestration and stabilization of organic matter is of particular interest. The percentage of gravimetric concentrations of organic matter in Arctic urban soils are almost always determined by the method of dichromate oxidation and are subject to extreme variability (from tenths of a percent to more than 90% in man-made soil formations), but the average carbon content in the surface soil horizons can be estimated at 5–7%. The surface humus-accumulative horizons are represented by a variety of morphological forms with the content of organic matter of various origins. The work also focuses on those forms of organic matter, the content of which is extremely small, but very important for the biogeochemical functioning of soils-polycyclic aromatic hydrocarbons and components of petroleum products, as well as labile forms of soil organic matter. We recommend that further studies of the organic matter system be conducted in urbanized areas since the carbon cycle there is severely disrupted, as well as carbon flows. The urbanization and industrialization processes in the Arctic are progressing, which could lead to a radical transformation of carbon ecosystem services.

Bioethanol: A New Synergy between Marine Chitinases from Bacillus haynesii and Ethanol Production by Mucor circinelloides

The fourth generation of bioethanol production is on a lookout for non-lignocellulosic biomass waste. One such candidate is chitin, the second most abundant biopolymer on earth. However, the crystalline nature of chitin hinders its application potential for bioethanol production. This limitation can be circumvented by hydrolysing this polymer into oligomers using chitinases. We used this hypothesis and isolated a Bacillus haynesii, a marine bacterium that utilizes colloidal chitin as a substrate and produces chitin oligosaccharides. Further, we utilized Mucor circinelloides to produce bioethanol using the chitin oligosaccharides in the shake flask. We investigated the effect of inoculum age, filling volume, different substrates, and substrate concentration on bioethanol production using Mucor circinelloides from Bacillus haynesii-produced chitin oligosaccharides. Bacillus haynesii demonstrated a maximum chitinase activity of 3.08 U/mL with specific activity of 96 U/mg at the 90th h. Chitin oligosaccharides produced by Bacillus haynesii were confirmed using mass spectrometry. Bioethanol concentration was determined using dichromate oxidation assay as well as gas chromatography. The research resulted in 7.4 g/L of ethanol from 30 g/L of chitin oligosaccharides, with a maximum ethanol yield of 0.25 g of ethanol/g substrate at the 55th h with 48 h inoculum in 80 mL of fermentation medium. Results suggest that chitin oligosaccharides from Bacillus haynesii are an effective and renewable substrate for bioethanol production.

Ethanol Production Comparison from Agricultural Waste of Cellulose Source Within Hydrolysis Hcl and Cellulose Enzyme

The production of Ethanol has been utilized through the process of cellulose isolation from agricultural waste such as corn husk, rice straw and rice husk. Isolation of cellulose with pretreatment delignification using, NaOH 2% to produces cellulose of corn husk 16,6921 g (22,25%), rice straw 16,9021 g (22,53%) and rice husk 16,3691 g (21,85%) then analyzed the functional groups using FT-IR and SEM analysis. Cellulose as much as 2 g is hydrolyzed using HCl 30% and cellulase enzymes to obtain sugar that is qualitatively tested with Benedict and Tollens reagent and quantitatively tested with Luff Schoorl method and produces highest sugar content of rice husk 8,64% and 10,95%. The next stage sugar of hydrolysis will be fermented using yeast (Saccharomyces cerevisiae) with 6 days, and then distilled at a temperature of 78-80oC. Ethanol was calculated by the potassium dichromate oxidation method to gave highest result from agricultral waste of ethanol chemical 5,97% and enzymatic 6,89% is rice husk.

Degradation performance of high-concentration coking wastewater by manganese oxide ore acidic oxidation.

The degradation of coking wastewater using a manganese oxide ore acidic oxidation was investigated. This work was performed in three stages. Firstly, the advantageous degradation conditions were measured by the degradation tests, and under the optimal conditions percentage degradation was obtained of 91.6% chemical oxygen demand measured by potassium dichromate oxidation (CODcr), 94.7% total nitrogen (TN), 98.3% phenols, 98.2% fatty acid, 89.5% tar, and 98.9% sulphide for the oxidized effluent, simultaneously cogenerating a Mn2+concentration of 46.2 g/L for Mn-electrolytic stock solution. Secondly, the transformation analysis of the special chemical group of coking wastewater contaminants illustrated that the employment of manganese oxide ore generated the degradation of low and high molecular weight organics, especially causing polymers to break down into oligomers. Thirdly, the electrochemical characteristics of the interface between wastewater and ore revealed that the contaminant degradation of coking wastewater greatly depended on the oxidation capacity of the surface oxide species, involving a simple answer to the MnO2 oxidation for small-molecule organic materials and a strengthening response to the MnO·OH oxidation for high-weight molecule organic substances. The treatment of coking wastewater using the Mn-oxide ore acidic oxidation process is an effective and value-added method, which is particularly applicable to high-concentration coking wastewater.

Determination of the total composition in gallic residue

n this study, ten batches of gallic residue were used as raw materials. The contents of total protein, total polyphenol and total C were determined by Coomassie bright blue method, folin-phenol method and potassium dichromate oxidation method respectively, and the methodology was investigated. The results showed that gallic residue contained more protein, polyphenols and sugar. There were significant differences in total protein and total polyphenol content between different batches, while the difference in total C content was small. The experimental method was simple, quick and convenient.

Causes clarification of the soil aggregates stability on mulched soil

Soil aggregates have great effects on soil properties and soil functions. Mulching (organic inputs) has been known as a factor influencing soil aggregate stability. Our study aimed to reveal the causes of the higher stability of soil aggregates under organic mulches. The primary soil characteristics such as organic carbon (Cox), humus quality (E4/E6), potential wettability index (PWI), and aromaticity index (iAR) were determined. The Cox was measured using rapid dichromate oxidation, and E4/E6 was measured using the UV-Vis spectrophotometry. The PWI and iAR were determined according to the intensity of selected bands in diffuse reflectance infrared spectra. Results showed that mulched plots contained higher Cox content in aggregates in comparison with whole soil. This indicates that the carbon was stabilized within the aggregates and sequestrated into the soil. The iAR was significantly higher after using the organic mulches, the aliphatic components of the organic matter thus contribute more to the aggregates stabilization. The PWI of aggregates was found to be higher after applying these mulches than in soil. Organic mulches are therefore able to reduce the wettability of the aggregates and also to protect the aggregate from dispersion with water.

Utilization of Corn (Zea Mays) wastes in Bioethanol production by Separate Hydrolysis and Fermentation

The study investigates the feasibility of producing bioethanol from corn (Zea mays) wastes. Corn cobs, husks and grains were collected from Githurai market and analysis was done in the Kenyatta university laboratory. Wastes were physically pre-treated to increase their surface area for enzymatic reactions. Separate Hydrolysis and Fermentation were carried out by using Aspergillus niger for enzymatic hydrolysis and Saccharomyces cerevisiae yeast for fermentation at different incubation temperatures (28oC, 30oC, 32oC) and times (24, 48, 72 and 96 hours). Fermentation was carried out in 150 ml cotton- plugged conical flasks containing 100 ml sample hydrolysates inoculated with 2 ml cultured yeast suspension. Ethanol concentration was determined by potassium dichromate oxidation method after each incubation time and expressed as % v/v whilst ethanol yield (l/kg) was derived from the ethanol concentration divided by the quantity of substrates used. Maximum yields of 1.84 l/kg, 1.76 l/kg and 2.05 l/kg were obtained from 50 g of pre-treated corn cobs, corn husks and corn grains respectively. The optimum temperature for maximum ethanol yield in all corn substrates was 30oC whilst incubation time 96 hours, 48 hours and 24 hours were optimum for ethanol production in corn cobs, corn husks and corn grains respectively. Results show that bioethanol can easily be produced from corn wastes and is recommended that they are used wisely for energy generation specifically bioethanol to add value to them rather than landfilling.

Quantification methods of pyrogenic carbon in soil with soil as a complex matrix: comparing the CTO-375 and Cr2O7 methods

ABSTRACT Pyrogenic carbon (PyC) or black carbon (BC), the residue of grassland and forest fires and fossil fuel combustion, plays an important role in carbon storage and pollutant adsorption in soil. To understand its roles in soil, it is necessary to accurately assess the PyC fraction. Soil is, however, a complex mixture of inorganic and organic matter, usually containing humic substances, i.e., non-PyC organic matter, in concentrations one to two orders of magnitude higher than PyC. This engenders difficulty in determining the PyC content in soils; thus, various quantitative methods have been proposed for different research purposes. In this study, the two widely used methods of chemo-thermal oxidation at 375°C (CTO-375) and acid dichromate oxidation (Cr2O7) method were reconsidered in terms of the suitability for determining the PyC content of soil by using model soil. The CTO-375 method was simpler, but the quantified PyC was suggested to be the combustion residue of non-PyC organic matter. By contrast, 29 to 40% of PyC content was determined as non-PyC organic matter by the Cr2O7 method. Therefore, we proposed an improved Cr2O7 method by increasing acidic K2Cr2O7 concentration threefold for quantification accuracy: although time-consuming, it resulted in the lowest overestimation on the PyC content, that is, 16 to 23% from non-PyC organic matter. The application of the improved Cr2O7 method to natural soil was confirmed with 99 to 103% certainty (recovery rate).

Estimation of the carbon valence from its average formal oxidation state in the soil organic matter

AbstractThe wet dichromate methods for the quantification of soil organic carbon on the basis of the reductant ability of soil organic matter have been widely used and they are still nowadays. The results obtained with these methods depart from the reference dry combustion with CO2 measurement and the discrepancies are interpreted in terms of incomplete oxidation under the wet dichromate conditions. However, in the calculations accompanying the dichromate methods a carbon valence (VC) equal to four is systematically used, even though the actual VC could be different. To assess the importance that an actual VC different from four could have in the mismatch between the wet dichromate methods and the reference dry combustion, the relationship between VC and the average formal oxidation state of carbon (zC) in soil organic matter should be known. On the basis of the definition of the equivalent weight and the average formal oxidation state, it is shown that a simple linear expression of the form VC = 4 – zC relates both concepts in carbon‐hydrogen‐oxygen‐nitrogen‐phosphorus‐sulphur compounds, which are representative of soil organic matter. On the basis of this equation the actual VC in soil organic matter can be assessed, thus helping in the interpretation of soil organic carbon determinations with the wet dichromate methods and, therefore, in the comparison between the dichromate methods and the reference dry combustion.Highlights Although questioned, a carbon valence of four is always used in the wet dichromate methods for SOC. How the valence of carbon depends on its average formal oxidation had not been previously shown. Both concepts are related through a simple linear equation: VC = 4 – zC. The mismatch between the dichromate oxidation and the dry combustion will be better interpreted.

Monitoring of the main parameters of pond water in order to obtain safe products for joint cultivation of sturgeon and carp fish

The article presents the results of studying the hydrochemical regimes of carp ponds in polyculture and for the introduction of sterlet (Acipenser ruthenus) into polyculture. The highest pH values were in pond 2, and in the second half of June and the first half of July exceeded the upper limit of normal (norm 6.5–8.5) by 0.3 and 0.5, respectively. In July, the upper limit of the norm was exceeded in the water of pond 1, by 0.1 and 0.2, respectively. From August, the pH of water increased in both ponds until October and in pond 2 the active reaction of water was higher, compared to pond 1, 5.08.2020, by 18.3 %, 20.08.2020 by 12.3 %, 5.09.2020, by 3.8 %, 20.09.20 and 5.10.20, respectively by 2.5 and 2.4 %. Higher in pond 2, compared with pond 1, was the permanganate oxidation of water in all studied periods, but the largest difference was 5.07.2020 and amounted to 6.9 mg O/l. In the second half of July, permanganate oxidation of water was the lowest, but was at the upper limit of normal, then in August increased sharply and was highest in October – 26.3 mg O/l in the pond 1 and 26.5 mg O/l in the pond 2. Dichromatic oxidation of water of the studied ponds was during the experiment in pond 2 slightly higher than normal and ranged from 50.5 (5.06.2020) to 57.9 (5.07.2020) mg O/l and only 20.07.2020 it was the lowest and was 34.2 mg O/l. In pond 1, the dichromate oxidation of water at the beginning of the experiment was 52 mg O/l, gradually decreased and 20.06.2020, was 46 mg O/l, in July, the chemical oxygen demand (COD) increased sharply to 63.6 and also decreased sharply up to 40.5 mg O/l. From 05.08.2020, COD rose by 27.8 % above normal, remained at approximately the same level during September and decreased to 62 mg O/l in early October. The content of free ammonia in the water during the whole period of fish farming exceeded the norm from 2.6 to 5 times, and the highest, except for 20.06.2020, it was in pond 2. The highest difference in ammonia content in the water of the studied ponds was 5.07.2020 and 5.10.2020, and was, respectively, 0.1 and 0.08 mg N/l. The content of ammonium nitrogen and mineral phosphorus in the water of the studied ponds exceeded the norm, and the nitrogen content of nitrates and nitrites was within the norm. In pond water, the concentration of Ca2+, Mg2+, Na+, CO32-, HCO3-, SO42-, Cl-did not exceed the norm. was 5.07.2020, and was 1.20 mg/dm³, which is higher than the norm by 20 %. The total hardness and mineralization of water in the studied ponds did not exceed the norm.

Subsoiling increases aggregate-associated organic carbon, dry matter, and maize yield on the North China Plain

BackgroundSoil degradation is one of the main problems in agricultural production and leads to decreases in soil quality and productivity. Improper farming practices speed this process and are therefore not conducive to food security. The North China Plain (NCP) is a key agricultural area that greatly influences food security in China. To explore the effects of different tillage measures on aggregate-associated organic carbon (AOC), the accumulation and transport of dry matter, and maize yield, and to identify the most suitable tillage method for use on the NCP, a field experiment was conducted at Shandong Agricultural University from 2016–2017 using plots that have been farmed using conservation tillage since 2002.MethodsIn this study, Zhengdan 958 summer maize was used as the test material and undisturbed soil and plant samples were obtained under four tillage methods—no-tillage (NT, tillage depth: 0 cm); rotary tillage (RT, tillage depth: 10 cm); conventional tillage (CT, tillage depth: 20 cm); subsoiling (SS, tillage depth: 40 cm)—which were used to determine the AOC and dry matter contents, as well as the yields of two summer maize growing seasons. Each sample was replicated three times and the AOC content was determined via potassium dichromate oxidation colorimetry. Potassium dichromate oxidized organic carbon in organic matter was employed to reduce hexadecent chromium into green trivalent chromium. Colorimetry was then used to determine the amount of reduced trivalent chromium and calculate the organic matter content.ResultsThe resulting data were statistically analyzed and the results showed that, compared with CT, the AOC contents with NT and SS increased by 5.65% and 9.73%, respectively, while that with RT decreased by 0.12%. Conventional tillage resulted in the highest mean dry matter weight when the maize reached maturity, which was 19.19%, 9.83%, and 3.38% higher than those achieved using NT, RT, and SS, respectively. No significant difference was found between CT and SS treatments, both of which tended to increase the accumulation of dry matter as well as its contribution of assimilates to grain yield post-anthesis. Compared with CT, the mean yield increased at a rate of 0.18% with SS, while yields declined at rates of 17.17% and 11.15 with NT and RT, respectively. The yield with NT was the lowest, though the harvest indices with NT and SS were higher than those with RT and CT. Overall, SS increased the accumulation of dry matter and its contribution of assimilates to grain yields post-anthesis, as well as the AOC content and yields, making it the ideal tillage method for the NCP.

Evaluation of a microplate spectrophotometer for soil organic carbon determination in south‐central Idaho

AbstractDetermination of soil organic carbon (SOC) is highly desirable for assessing fertility and carbon sequestration; however, numerous methods of determination warrant study of method agreement. Recently, a novel method was developed following dichromate oxidation using a microplate spectrophotometer. This novel method was compared with (a) total C by dry combustion − soil inorganic carbon (DCw/o pretreatment–pressure calcimater [Pcal]); (b) traditional Walkley–Black titration (WBTIT) and (c) loss on ignition (LOI360°C) in calcareous soils of south‐central Idaho (n = 75) in conjunction with North American Proficiency Testing program soils (n = 10). A two‐way ANOVA was fit with soils as a blocking factor to identify any difference between methods; means were separated using Tukey's honestly significant difference test (α = .05). Additional comparisons were made for all soils (n = 85) and for soils in the lower 75th percentile of SOC determined by WBTIT (n = 56) using regression analysis. Only the WBTIT and LOI360°C methods were statistically equivalent nevertheless there was high agreement (Lin's concordance coefficients &gt; .90) between all methods (n = 85). Under low SOC soils (n = 56) the agreement between all methods decreased, but the Walkley–Black spectrophotometric method (WBSPEC) method fit other methods comparatively well r2 = .71, .74, and .78 for LOI360°C, DCw/o pretreatment–Pcal, and WBTIT respectively. The WBSPEC method provided estimates of SOC between the methods currently used in the region while reducing hazardous waste generation over traditional WBTIT and sample handling over LOI360°C and DCw/o pretreatment–Pcal methods, positioning it as a sensible option for SOC determination in low SOC calcareous soils of south‐central Idaho.

Сучасний екологічний стан поверхневих вод р. Трубіж

The problem of environmental safety of water bodies is relevant today, especially for the basins of small and medium-sized rivers, which are clear indicators of the environment state. One of them is the Trubizh River. The water resources of this river are formed under the anthropogenically changed conditions of the drainage and humidification complex of the Trubizh reclamation system. These resources are also receivers of effluents from point and diffuse sources. Thus, there is a need for constant monitoring of the ecological condition of the river. The water quality of it is a consequence of anthropogenic activities in the watershed. The aim of the work is a comprehensive assessment of the Trubizh River ecological condition under the modern conditions of water quality formation. The analysis has been conducted using official data from the state monitoring of water quality for 2015-2019 years and our own research for 2015-2016 years. 7 observation points have been considered from souse to mouth of the river: border areas of Brovary and Baryshivka; Baryshivka – 1 km above and 0.9 km below the village, Pereyaslav-Khmelnytsky – 0.5 km above and 1 km below the town, the mouth of the Alta and Trubizh rivers). We used such methods as analytical (determination of water quality indicators according to generally accepted standardized methods); analysis, systematization and generalization of the monitoring database; method of calculation of integrated block indices and complex ecological index of water quality (IE). It is established that during the five-year period (2015-2019) according to the weighted average and the worst values of the complex ecological index (IEworst 4.2) the waters are characterized as "satisfactory", "slightly polluted" of the III class quality 4 category. In 2018 and 2019 years, there was a deterioration in water quality by one category (III quality class 5 category) - "mediocre", "moderately polluted" water. This is due to a set of conditions of natural and climatic (insufficient rainfall and rising air temperature) and anthropogenic nature (water pollution, unauthorized surface water abstraction, runoff obstruction, etc.). It is noted that Trubizh river is characterized by stable uniform spatial water pollution. The largest values of IE are recorded in the area of influence of the village Baryshivka (IE worst 3.7-3.8) and Pereyaslav-Khmelnytskyi in the sampling points: the Alta river mouth (IEworst 4.0) and the Trubizh river mouth (IEworst 3.7). The water quality in these sampling points corresponded to class III of category 4 and was generally characterized as "satisfactory", "polluted". In general, the deterioration of water quality is caused by organic pollution (according to the indicator of dichromate oxidation (IV class, 6 category), BOD5 (Biochemical oxygen demand) (III class, 5 category), nitrogen compounds (ammonium, nitrite and nitrate) – V class, 7 category) and phosphorus compounds (phosphate ions – III class, 5 category), total iron and general chromium – III class, 5 category, phenols and SSAS (synthetic surfactants active substances) – IV class, 6 category. Thus, one of the main reasons for the degradation of the river is the anthropogenic conditionality of its development as a result of the urbanized and agricultural areas impact. The obtained data open the prospect of continuing work on monitoring and assessing the ecological status of aquatic ecosystems of the Trubizh River for the further development of scientifically based recommendations. It is necessary for making management decisions for sustainable use and protection of surface waters and restoration of aquatic ecosystems of Trubizh River Basin.

ФОРМЫ МИГРАЦИИ РАДИОНУКЛИДОВ (U и Th) В ПРИРОДНЫХ ВОДАХ В РАЗЛИЧНЫХ ГЕОХИМИЧЕСКИХ УСЛОВИЯХ НА ОСНОВЕ РАСЧЕТНЫХ И ЭКСПЕРИМЕНТАЛЬНЫХ ДАННЫХ

Актуальность исследования обусловлена необходимостью учета разнообразия форм миграцииприродных радионуклидов при смене геохимических условий, а также при прогнозированиирадиоэкологического статуса гидроэкосистем. На территории Семипалатинского испытательного полигона миграция естественных радионуклидов в водных системах слабо изучена, расчет форм миграции урана и тория при смене геохимических обстановок будет информативен для понимания миграции широкого спектра трансурановых радионуклидов. Цель: определить формы миграции урана и тория в природных водах в зависимости от размеров частиц и с учетом широкого спектра компонентов, рассчитать формы их миграции в ручьях и озерах. Объекты: воды ручьев горного массива Дегелен, воды озер экспериментальных площадок Семипалатинского испытательного полигона, модельные гидрогеохимические системы. Методы. Формы нахождения природных радионуклидов исследовали insitu методомкаскадного фракционирования природных вод. рН, Eh вод определяли методом потенциометрии, общую минерализацию – кондуктометрией. Определение основных ионов воды и отдельных элементов произведено методами титриметрии (HCO3–, CO32–, Cl–, Ca2+, Mg2+), оптико-эмиссионной спектрометрии (Na, K, Ca, Mg, Fe, Si), а также ионной хроматографии (Cl–, SO42–). Содержание растворенных органических веществ определяли по перманганатной и бихроматной окисляемости, методом каталитического сжигания, а также по интенсивности UV сигнала. Содержание U и Th определяли методом масс-спектрометрии. Результаты. Определены особенности переноса урана и тория в природных водах различных водных объектов Семипалатинского испытательного полигона,и обозначены определяющие их процессы. Установлено, что сульфат-ион в водах ручьев является индикатором интенсивности водообмена и скорости окисления сульфидных минералов, определяющих выход в раствор значительных концентраций урана. Уран связан с органическими и органоминеральными комплексами и подвержен трансформации форм нахождения в случае изменения геохимических условий среды. Для тория в большей степени, чем для урана, характерен коллоидный транспорт. Доминирующей миграционной формой этих элементов являются взвешенные компоненты природных вод. Отношение Th/U в растворенной форме достаточно стабильно по сравнению с коллоидными и взвешенными формами. Для вод с разным гидродинамическим режимом прослеживается отличие в степени выраженности влияния терригенной составляющей.

Modified self‐adaptive model for improving the prediction accuracy of soil organic matter by laser‐induced breakdown spectroscopy

AbstractSoil organic matter (SOM) significantly influences soil fertility, biology, and the global C cycle. Laser‐induced breakdown spectroscopy (LIBS) is attractive, as it can measure SOM accurately and quickly with minimal sample preparation and effective cost. Our earlier self‐adaptive (SA) model based on individual distances between LIBS soil spectra coupled with partial least squares (PLS) was favorable for SOM prediction. To optimize this model by including soil identification via the use of a hybrid distance between the spectra, two hybrid distance SA models to enhance SOM predictions from LIBS spectra in 250 Chinese topsoils were built and studied. The models used LIBS soil spectra and SOM content measured by the traditional potassium dichromate oxidation method for calibration. The performance of these models for the validation set was compared with the conventional no‐identification PLS model and SA‐PLS models. The modified models that used (a) a hybrid of Euclidean distance (ED) and angle cosine (SAxc–PLS), and (b) a hybrid of ED and the distance of response y (SAxy–PLS) improved SOM predictions , with a R2 of 0.908, a RMSE of 5.65 g kg−1, and a residual prediction deviation (RPD) of 2.91 in the validation set for SAxc–PLS; and a R2 of 0.900, a RMSE of 5.49 g kg−1, and a RPD of 2.99 in the validation set for SAxy–PLS. The improved performance mainly resulted from simultaneous consideration of diversity and correlation of the spectra. Therefore, modified SA models hold great potential for SOM prediction, especially for different soils.

Study of the effects of mineral salts on the biofilm formation on polypropylene fibers using three quantification methods.

The microbial biofilms are ubiquitous in nature and represent important biological entities that affect various aspects of human life. As such, they attracted considerable attention during last decades, with the factors affecting the biofilm development being among the frequently studied topics. In our work, the biofilm was cultivated on the surface of polypropylene fibers in a nutrient medium inoculated by the suspension of two unsterile soils. The effects of ionic strength and valence of salt on the amount of the produced biofilm and on composition of biofilm microbial communities were investigated. The effect of valence was significant in some OTUs: Arthrobacter/Pseudarthrobacter/Paenarthrobacter and Bacillus with positive response to monovalent salt (KCl) and Streptomyces, Lysinibacillus, Pseudomonas, and Ensifer with positive response to divalent salt (MgSO4). The significant preference for a certain concentration of salts was observed in the case of OTUs Agrobacterium, Bacillus (both 100mM), and Brevundimonas (30mM). A new quantification method based on measuring of oxidizable organic carbon in biofilm biomass, based on dichromate oxidation, was used. We compared the results obtained using this method with results of crystal violet destaining and measuring of extracted DNA concentration as proxies of the biofilm biomass. The dichromate oxidation is simple, inexpensive, and fast, and our results show that it may be more sensitive than crystal violet destaining. The highest biomass values tended to associate with high concentrations of the divalent salt. This trend was not observed in treatments where the monovalent salt was added. Our data confirm the importance of inorganic ions for biofilm composition and biomass accumulation.