Source Of Secondary Pollution Research Articles

High microplastic pollution in marine sediments associated with urbanised areas along the SW Bulgarian Black Sea coast

This study aims to provide baseline data on microplastic (MP) concentrations in beach and seabed sediments of the SW Black Sea coast, and to identify possible sources of MP pollution in the area. MP concentrations in beach sediments in urbanised coastal areas, as well as in all seabed sediments, were on average higher than in other parts of the Black Sea and most other European seas. Urban coastal areas showed the highest average MP concentrations (mean ± SD): 464.44 ± 272.50 MP·kg−1 dry sediment in beach samples, 825.93 ± 396.30 MP·kg−1 dry sediment in seabed samples, while coastal sediments in an area with no local anthropogenic activities had significantly lower average MP concentrations: 84.44 ± 147.57 MP·kg−1 in beach samples, and 550.62 ± 245.71 MP·kg−1 in seabed samples. Possible identified sources of MPs include sewage water discharges, urban waste, coastal fisheries and aquaculture, as well as accumulation of marine litter on beaches and in adjacent offshore areas, serving as sources of secondary MP pollution.

Assessing Organochlorine Pesticide Behavior in Agricultural Watershed Soil, Water and Sediment: A Dynamic Modeling Approach

ABSTRACT The utilization of pesticides has experienced a substantial rise in order to enhance both the quantity and caliber of the produced goods. Agricultural runoff, a major source of nonpoint pollution, adversely impacts surface water, groundwater, soil and sediment quality in the watershed. Especially, organochlorine pesticides have adverse effects on the environment because of their toxicity, persistence and bioaccumulation. In this study, the presence of organochlorine pesticides (DDTs- dichlorodiphenyltrichloroethane and HCHs- hexachlorocyclohexane) in the environment of the dryland agricultural watershed, was determined. For this purpose, soil, sediment and water samples from the landscape of pond were collected. The concentrations of organochlorine pesticides in water, sediment, and soil ranged from 0.0005 to 0.0138 μg/L, 0.03 to 1.02 μg/kg, and 0.54 to 52 μg/kg, respectively. The persistence of these pesticides in soil and sediment poses long-term risks to both terrestrial and aquatic ecosystems. Sediment, as a significant reservoir for these contaminants, can act as a secondary source of pollution, releasing pesticides back into the water column under certain environmental conditions. Similarly, soil contamination not only affects plant health and productivity but also leads to further leaching and runoff into water bodies. The behavior of a toxic substance in water, soil and sediment environment, which is organochlorine pesticide, in a well-mixed lake watershed, was modeled using mass balances in the lake. Statistical analysis, including a paired t-test and calculation of the Nash-Sutcliffe index, confirms the consistency and reliability of the model’s predictions compared to observed data. Simulated concentrations closely matched observed values, and the distribution patterns and trends remained consistent across different months. Moreover, the Risk Quotient (RQ) for DDTs and HCHs is less than 0.1, indicating low ecological risk.

Ratios of organic mass to organic carbon in fine particulate matter at urban sites in China and Korea during winter and summer.

This study evaluates the composition and seasonal characteristics of fine particulate matter (PM2.5) during winter and summer through simultaneous measurements conducted at the Gwangju Institute of Science and Technology in South Korea and the Changping campus of Peking University in China. PM2.5 samples were concurrently collected at both sites, and chemical analyses were conducted to quantify various components, including carbonaceous materials, ionic species, and metals. Although the average PM2.5 concentrations were comparable between the two sites, there were distinct differences in the concentrations of major components. Organic indicator compounds were analyzed to discern the contributions of primary and secondary pollution sources. Changping displayed a mix of primary and secondary pollution, characterized by higher concentrations of primary organic carbon (POC) such as polycyclic aromatic hydrocarbons and hopanes, compared to Gwangju. In contrast, Gwangju demonstrated a higher prevalence of secondary organic carbon (SOC), particularly water-soluble organic carbon not related to biomass burning (WSOCnbb) and various polar organic compounds. The organic mass to organic carbon (OM/OC) ratios estimated using the mass balance method revealed significant differences, with Gwangju showing a higher ratio of 2.3 compared to 1.9 at Changping, indicating a greater influence of secondary pollutants at Gwangju. Additionally, both Changping and Gwangju exhibited higher OM/OC ratios in summer (Changping: 2.0, Gwangju: 2.5) compared to winter (Changping: 1.8, Gwangju: 2.2), indicating seasonal differences in organic mass contributions to PM2.5. These findings underscore the importance of accounting for spatial and seasonal variations in air pollution studies and suggest that updating commonly used OM/OC ratios could enhance the reliability of research outcomes.

Bio-Based Materials as a Sustainable Solution for the Remediation of Contaminated Marine Sediments: An LCA Case Study.

Contaminated sediments may induce long-term risks to humans and ecosystems due to the accumulation of priority and emerging inorganic and organic pollutants having toxic and bio-accumulation properties that could become a secondary pollution source. This study focused on the screening of novel bio-based materials to be used in the decontamination of marine sediments considering technical and environmental criteria. It aimed to compare the environmental impacts of cellulose-based adsorbents produced at lab scale by using different syntheses protocols that involved cellulose functionalization by oxidation and branching, followed by structuring of an aerogel-like material via Soxhlet extraction and freeze-drying or their combination. As model pollutants, we used 4-nitrobenzaldehyde, 4-nitrophenol, methylene blue, and two heavy metals, i.e., cadmium and chromium. When comparing the three materials obtained by only employing the Soxhlet extractor with different solvents (without freeze-dying), it was observed that the material obtained with methanol did not have a good structure and was rigid and more compact than the others. A Life Cycle Assessment (LCA) was conducted to evaluate the environmental performance of the novel materials. Apart from the hierarchical categorization of the materials based on their technical and environmental performance in eliminating organic pollutants and heavy metal ions, it was demonstrated that the cellulose-based material obtained via Soxhlet extraction with ethanol was a better choice, since it had lower environmental impacts and highest adsorption capacity for the model pollutants. LCA is a useful tool to optimize the sustainability of sorbent materials alongside lab-scale experiments and confirms that the right direction to produce new performant and sustainable adsorbent materials involves not only choosing wastes as starting materials, but also optimizing the consumption of electricity used for the production processes. The main results also highlight the need for precise data in LCA studies based on lab-scale processes and the potential for small-scale optimization to reduce the environmental impacts.

Study on the deposition characteristics of fine particles at local components in air conditioning ventilation ducts

Air conditioning ventilation ducts are widely used in contemporary buildings. The change of airflow direction in the ducts local components can easily lead to the deposition of particles, which can easily form a secondary source of indoor air pollution and have an adverse effect on human health. Based on this, this paper utilizes the existing experimental data to validate the numerical simulation. The Reynolds stress turbulence model combined with the method of enhanced wall function was used to investigate the deposition characteristics of fine particles in different local components. For the first time, local deposition rates and deposition hotspots were proposed to analyze the simulation results. The results show that the local deposition rate of the particles with a particle size of 1μm do not differ much on each wall surface, and the particles are deposited more uniformly on each wall at the local components, with a difference of less than 10 %, and the maximum local deposition rate is on the outer wall of the local components. When the particle size is larger than 10μm, the local deposition rate on the outer wall of the local component increases significantly, with a maximum increase of 23.3 % (compared to 5μm particles), and the maximum local deposition rate increases slowly with increasing air velocity, with a maximum increase of less than 8 %. The effect of increasing particle size on the maximum local deposition rate is much greater than the increase in air velocity. With the increase of air velocity and particle size, the deposition hotspots of both the 90° bend and the T-type tee duct migrate to the middle of the wall, and the deposition hotspots of the 4-way duct migrate to the inside of the wall.

Detection and characterization of micro‐ and nano‐plastics in wastewater: Current status of preparatory & analytical techniques

AbstractMicro‐ and nano‐plastics (MNPs) are ubiquitous emerging pollutants that have gained global traction due to their persistent nature and potential risks to the environment and human health. The physico‐chemical properties of MNPs such as size, shape, density, surface charge and hydrophobicity are quite different from macro‐plastics, which render them unique behavior exemplified by high rate of diffusion, high mobility, easy uptake by organisms, high toxicity, and potential of bioaccumulation. Human exposure to MNPs causes serious health impacts including apoptosis, necrosis, inflammation, oxidative stress, metabolic disorders, and hampered immune responses. The hazardous nature and high persistence of MNPs in the environment necessitates accelerated studies focused upon their detection, quantification, impact analysis, and risk assessment. All kinds of wastewaters whether municipal, agricultural, or industrial, consist of significant loads of MNPs and act as secondary source of MNP pollution in groundwater and soil. Wastewater is highly complex in composition and there are several impediments in the accurate detection and identification of MNPs in this matrix owing to the in‐efficient sampling methods, lack of standardized methodologies, and non‐reproducibility of data. This review provides an overview of currently available techniques for sampling, detection, identification, and characterization of MNPs in wastewater. A critical commentary on the challenges and limitations of these techniques has been given and strategic combinatorial methods have been suggested for efficient and reliable MNP analysis in wastewater samples. The article also highlights novel sensor‐based methods enabling rapid and accurate detection of MNPs in wastewater.

The former industrial site of the Angarsk Metallurgical Plant (Svirsk, Russia) 10 years later: current geochemical state and interannual change analysis based on Earth remote sensing data

The former industrial site of the Angarsk Metallurgical Plant (Svirsk, Russia) 10 years later: current geochemical state and interannual change analysis based on Earth remote sensing data

INCREASED RISK OF CHEMICAL TERROR ATTACKS

The risk of using highly toxic chemicals in a terrorist attack is resurfacing. Over the last fewdecades, terrorists have proven that they can source, develop and produce their own toxicchemicals. These substances are particularly dangerous for civilians who do not have access tothe protective equipment to be used in the event of contamination. It is impossible to guaranteefull public security in relation to the threats of chemical terrorism. Only trained, functioningand cooperating elements of state crisis response systems (mainly: medical rescue services,fire brigades, the police and the army) are capable of minimising the negative effects of theseattacks on the civilian population. This problem is becoming particularly important in view of theongoing Russian-Ukrainian war and the potential use of chemical weapons by the Russian army.An important problem impacting the extent of poisoning after a chemical attack is secondarycontamination of people and emergency equipment. The authors, through a detailed descriptionof the sources of secondary pollution, propose a number of solutions aimed at minimizing the riskof poisoning in people who are not directly exposed to chemical hazardous agents as a result ofsecondary contamination. The proposed solutions are based on the experience of chemical troopsin the elimination of chemical contamination of a large number of people, as well as the experienceof the authors related to the implementation of research and development projects regarding theprotection and operating procedures of rescue services in CBRN contamination zones.

Simple synthesis of floating Fe2O3/Luffa catalysts for the photo-Fenton degradation of methyl orange at near neutral pH

Although widely used in the textile industry, methyl orange is considered one of the most toxic dyes, which have negative impacts on the aquatic environment and needs to be removed from water bodies. Hence, the present paper reports the synthesis of new floating photo-Fenton catalysts based on the immobilization of Fe2O3 nanoparticles on the surface of Luffa sponges for the oxalate-induced-degradation of methyl orange. The floating catalytic sponges were prepared through a simple precipitation method followed by a reflux heating process and then characterized by field emission scanning electron microscopy, X-ray diffraction, atomic absorption spectrometry, and nitrogen adsorption-desorption experiments. According to the experimental results, methyl orange was effectively degraded over our floating catalytic sponges underlight illumination at near neutral pH. The catalytic activity was also found to be enhanced with the increase in crystallinity of Fe2O3 nanoparticles, which can be achieved by the reflux heating. Besides, owing to the floating feature, these sponges are easily separated from the solution, thereby not forming a secondary source of pollution for water

The influence of the environmental factors on the accumulation patterns of toxic elements in Plantago lanceolata sampled in the area under strong anthropopressure

The study aims to explore the environmental factors which activate accumulation abilities of Plantago lanceolata in the research area under strong anthropopressure resulting from the long-term pollution originating from copper mining-metallurgical activities in Southeastern Europe. Sampling was performed at the most endangered sites regarding its proximity to the major and/or secondary pollution sources, as well at the control site. The content of toxic elements (Al, Cu, Fe, Mn, Ni, Pb and Zn) was determined in the roots, leaves, stalks and flowers of P. lanceolata. The anthropogenic origin of environmental contamination was denoted through the high concentrations of Cu, Pb and Zn in the leaves of P. lanceolata, reaching toxic levels, combined with the enrichment of plant parts (Enrichment factor >2), especially with Cu (as well as with Al, Fe, Ni and Zn) in samples from the immediate proximity to the copper smelter or at the prevailing wind directions. Biomonitoring potential, assessed through the correlations between toxic element content, as well as the values of Enrichment factor, was indicated for roots (in the case of Cu), all the aboveground plant parts (Fe) and stalks (Zn). The results have shown that the contents of toxic elements in plant parts as well as phytoremediation of P. lanceolata were dependent on soil element content, soil physico-chemical properties and soil enzyme activities, which were regarded as the main environmental drivers affecting phytoremediation ability. The analysis of biological factors (bioconcentration, translocation and bioaccumulation factor) indicated exclusion strategy and possible usage of P. lanceolata in phytostabilization of Zn. The results indicated that the study area is 'environmental hotspot' with potential threat to human health due to the high levels of bioaccumulation of the investigated toxic elements in P. lanceolata parts.

The reciprocity principle in mulch film deterioration and microplastic generation.

Plastic film mulching stands as a globally employed agricultural technology pivotal to agricultural progress. Nevertheless, the environmental degradation of plastic mulch films underscores their role as a major source of secondary plastic pollutants, particularly microplastics. While a growing body of research has drawn attention to the rising issue of microplastic pollution and its environmental implications stemming from the use of plastic mulch films, there remains a significant knowledge gap regarding the kinetics and rate-limiting mechanisms governing the generation of microplastics during processes driven by plastic photodegradation. Moreover, a comprehensive quantification of the connection between mulch deterioration and the behavior of microplastic release and accumulation has yet to be fully realized. In this study, a kinetic equation was formulated to characterize the degradation of plastic mulch films and the subsequent release and accumulation of microplastics under light exposure. The results demonstrate that with increasing irradiation time, the change in the release rate exhibits a bell-shaped Gaussian probability distribution, while the cumulative alteration of microplastics follows a Gaussian distribution. Remarkably, once the exposure time reaches μ + 3σ, the accumulation plateaus at 99.7%. This research establishes a theoretical framework for the prospective assessment of plastic mulch lifespan and its environmental repercussions. Moreover, the findings provide valuable insights for optimizing plastic mulch design and devising strategies to mitigate microplastic pollution.

Unveiling threats to glacier biota: Bioaccumulation, mobility, and interactions of radioisotopes with key biological components

Contemporary melting glaciers are considered a secondary source of pollutants including radionuclides. Cryoconite - biogenic sediment on the glacier surface - exhibits high concentrations of natural and anthrophogenic radioisotopes. Understanding the interactions between radioisotopes and organisms is essential for evaluating their potential impact on glacier-related ecosystems. Using a multidimensional approach and intensive sampling (17 glaciers), we investigated the relationships between activity concentrations of 137Cs and 210Pb and various biotic components of cryoconite such as the amount of organic matter, chlorophyll concentration, the ratio of cyanobacteria to all bacteria, and size of cryoconite granules. Additionally, to better understand the bioavailability and fate of radioisotopes in this ecosystem, we measured the uptake ratio of 137Cs, 210Pb, 238Pu, and 239+240Pu in the top consumers, and examined the mobility of radioisotopes by measuring 137Cs and 210Pb activity concentrations after a parallel extraction using media with different specific ion exchange capacities. The activity concentrations of both 137Cs and 210Pb showed a large variability reaching 5.8 kBq kg−1 and 7.2 kBq kg−1, respectively. Their activity concentrations were positively related to the amount of organic matter, however, the 210Pb also increased with the chlorophyll concentration. This might be due to the difference in the deposition of both elements: lead, being deposited constantly, binds also to currently developing communities, while caesium deposition peaked in the 1960s. The mobility analysis revealed that the loosely bound fraction of 210Pb was more strongly related to organic-metallic complexes than 137Cs. Firmly bound radioisotope fractions (anhydrous interlayer sites of minerals) were three times higher for 137Cs than for 210Pb. The median uptake ratios of radioisotopes were determined as 0.07–0.111 for 137Cs, 0.177 for 210Pb, 0.07 for 239+240Pu. Our findings emphasize the importance of organisms in the accumulation of radioisotopes on glaciers and suggest an impact of radionuclides on glacier organisms.

Spatial Distribution of Trace Elements in Sub-Surficial Marine Sediments: New Insights from Bay I of the Mar Piccolo of Taranto (Southern Italy)

Contaminated marine and coastal sediments represent the main source of secondary pollution for the aquatic environment and marine fauna, affecting, directly and indirectly, ecosystems and human health. The assessment of the distribution of chemical pollutants in marine sediments can therefore be considered a preliminary step for understanding the possible circulation of pollutants in the marine environment and planning any targeted and efficient reclamation activity. This study provides new insights on the environmental status of Bay I of Mar Piccolo basin (Southern Italy) by proposing an integrated investigation approach to define the distribution of trace metals and evaluate the thickness of the sediments potentially affected by pollution. To this aim, the concentrations of As, Cd, Cr, Cu, Hg, Ni, Pb, Sn, and Zn are estimated for sediment samples collected from 19 cores, and specific environmental indices are calculated. Due to its remarkable environmental and economic relevance, the area of Taranto has been selected as a case study to evaluate the effectiveness of the proposed method in supporting the identification of hotspot areas for which priority remediation activities are needed.

Distribution of Heavy Metals in Water and Bottom Sediments in the Basin of Lake Gusinoe (Russia): Ecological Risk Assessment

Fresh water scarcity is considered a significant component, and potentially one of the most critical, of global climate change. With the rapid development of industry, there is an increasing risk of freshwater contamination by heavy metals (HMs). The danger of HM pollution is also attributed to their accumulation, which can subsequently become a source of secondary pollution in aquatic environments. In the Lake Gusinoe basin, located in Russia, concentrations of HMs were measured in both water and bottom sediments within the lake area, as well as in inflowing and outflowing watercourses. Ecological risk indices were also calculated for the Gusinoe basin. Our results showed that the average concentrations of Fe, Zn, Cr, Ni, Cd, and Pb in the water did not exceed the maximum allowable concentrations (MACs) set by Russian national standards and WHO standards, while the concentrations of Mn and Cu exceeded the corresponding MACs during winter, spring, and autumn possibly due to decomposition of aquatic vegetation and influx from groundwater sources. The average concentrations of the investigated HMs in the BSs did not exceed the background values. The water hazard index indicated a low risk for all samples in the lake water area. For all BS samples, the geoaccumulation index (Igeo) and the Pollution Load Index (PLI) indicated low pollution levels, while the values of the Enrichment Factor (EF) and the Contamination Factor (CF) indicated moderate pollution in the central part of the lake. The Ecological Risk Factor (Er) for Cu in BSs at points near major settlements and in the Tel River indicated moderate pollution. The Potential Ecological Risk Index (RI) in all investigated BS samples indicated a low risk of contamination.

The inability of organic coagulants to purify potable water to its best attainable quality

Organic coagulants have gained increasing popularity over the past 30 years because they are considered cheaper and more user-friendly than traditional mineral hydrolysing coagulants. Regrettably, in-depth studies have not yet been conducted on their ability to purify water to a healthy palatable drinking quality which is risk-free for lifetime consumption in terms of the national standard for drinking water quality of various countries worldwide, and does not become a source of secondary pollution in the reticulation system. The objective of this paper is to provide information about the natural organic matter (NOM) removal efficiency attained at different waterworks purifying water with different organic coagulants, and to compare this with that attained using mineral coagulants. The findings presented in this article prove that organic coagulants are not an equivalent replacement for mineral coagulants, as the purified water is of an inferior quality which does not comply with the limits set by national standards of different countries worldwide.

Risk assessment and source analysis of heavy metal contamination in the soil of the Juanshui River Mouth

ABSTRACT Heavy metals with a high concentration value in the soil are detrimental to the soil ecosystem. In this study, 96 samples were taken from two soil sections (A-A, B-B) in the mouth of the Juanshui River to analyze heavy metal pollution. Soil pollution status and the ecological risk were investigated using Nemerow and the potential ecological risk index. The sources affecting pollution and pollution distribution characteristics were exhibited based on Inverse Distance Weighted (IDW), principal component analysis (PCA), and Statistics. Pollution in the soil of the mouth of the Juanshui River had reached a moderate level. Hg and Cd were the main potential ecological risk contributions. Coal burning and agricultural chemicals were the predominant pollution source in the study area. In order to avoid the soil of the river mouth becoming a secondary pollution source for water bodies and resulting in a vicious circle of heavy metal pollution, heavy metals in the soil of the river mouth of China should be mainly managed and controlled.

AEROSPACE TECHNOLOGIES FOR ASSESSING SOIL CONTAMINATION

Actuality. Studies of soil pollution assessment are based on scientific principles that define a complex system of environmental safety management in the context of increased exposure to sources of secondary dust pollution of the atmosphere. To ensure environmental safety under conditions of high levels of dust pollution, it is necessary to apply and improve the relevant models. Among the many types of environmental pollution, dust pollution of the atmospheric air and the deposition of harmful substances on the soil are particularly dangerous. This pollution can take two forms: direct emissions from industrial enterprises (primary) or the formation of secondary pollution through physical and chemical processes in places where dust-like waste is stored. Fine waste after air purification with dimensions of less than 100 microns is particularly hazardous. In modern environmental monitoring and assessment of soil pollution, special attention is paid to remote methods that allow for more effective monitoring of the impact of human activity and solving environmental problems. The use of unmanned aerial vehicles is one such method that has positive results. The purpose of the article is to solve the scientific problem of improving aerospace methods based on unmanned aerial vehicles (UAVs) for monitoring and assessing the quality of soil pollution. The object of the study is the use of aerospace tools for monitoring and assessing the condition of soil cover. To achieve this goal, the following tasks have been defined: to study the current state and ways to improve the efficiency of UAVs in the system of environmental monitoring of soils; to develop models of environmental assessment; to analyze existing approaches to the use of aerospace assets for monitoring and assessing the state of soil cover. Conclusions: a methodological approach based on a modified method of the comprehensive assessment of the level of technogenic hazard of industrial facilities is proposed to assess the state of environmental safety in conditions of intense dust pollution of the atmospheric air.

Investigation on metal geochemical cycling in an anthropogenically impacted tidal river in Belgium

The geochemical behavior of metals in water and sediment was investigated in the tidal section of the Zenne River in Belgium. Twelve-hour sampling campaigns were performed in October 2013 and March 2021 at the mouth of the Zenne River, under dry and rainy weather conditions respectively. Water samples were collected every hour while the passive samplers of Diffusive Gradients in Thin-films (DGT) were deployed continuously during a tidal cycle. In addition, bottom sediments were sampled at the tidal station and water samples were taken upstream and downstream of that station to identify the metal sources. The highest concentrations of Fe, Mn, Pb, Cr, Ni and Zn appear at low tide, indicating the Zenner River as a main source. However, for Co, Cd and Cu, other sources including upstream transport may explain their behavior during a tidal cycle. Fe, Pb and Cr are essentially transported in the particulate phase (<10 % dissolved) while the other metals in the dissolved phase (20 to 90 %). Rainfall and wind gust events also play an important role in trace metal distribution, increasing sediment resuspension and metal desorption. A good agreement was found between the time-averaged dissolved and DGT-labile metal concentrations with the exception of Cu and Fe, which form strong organic Cu complexes and Fe colloids respectively. The sediments of the tidal Zenne are contaminated by trace metals, thus acting as a secondary pollution source to the river. The reductive dissolution of Mn and Fe oxyhydroxides and the release of associated trace metals are the main mobilization mechanisms. Knowledge of the upstream and downstream levels in the water column, the benthic fluxes, which are based on turbulent diffusion, and the partitioning between dissolved and particulate phases allow to explain the metal concentration variations during the tidal cycle.

Определение антропогенного загрязнения по физико-химическим характеристикам талого снега

The state of the environment in cities is determined by the degree of pollution of individual components of the environment. Geochemical anomalies in urban agglomerations are often formed in pollution depositing media such as soil, snow cover, bottom sediments. The purpose of the study is environmental monitoring of anthropogenic impact in different areas of Smolensk and Vyazma according to the physical and chemical characteristics of melted snow. Snow was chosen as the object of the study, because it accumulates many substances entering the atmosphere, and subsequently can become a source of secondary pollution of the soil cover, underground and surface waters. The study determined organoleptic parameters (smell, color, turbidity, the presence of sediment in melt water), chemical parameters (the number of suspended particles, pH, total rigidity and mineralization, the amount of organic substances).The presence of chloride ions (Cl-), sulfate ions (SO42-), nitrate ions (NO3-), nitrite ions (NO2-), bicarbonate ions (HCO3-) and ions of some heavy metals (Pb2+, Cu2+, Fe3+) have been determined. Bioindication of the studied samples on watercress has been carried out in parallel. A low level of air pollution in Smolensk and Vyazma has been established. The greatest contribution to the formation of the level of pollution in the cold period of the year is made by suspended substances, iron and manganese compounds in concentrations exceeding the maximum permissible concentration. The concentration of impurities depends on the distance from large industrial objects, automobile and railway objects, sanitary and technical condition and cleaning regime of the territory. The courtyard territories of Smolensk and Vyazma are the cleanest. The largest part of snow pollution is provided by the thermoelectric power stations and transport. Samples taken near car parks, railway tracks and near the thermoelectric power stations were the most unfavorable.

On the shapes of deep slopes of radiocesium vertical profiles in lake sediments

The shapes of the deep slope (below the maximum values) of the vertical profiles of radiocesium activity concentrations in the sediment samples taken in 2003–2012 in the Lakes Juodis, Tapeliai and Red lake were studied. The Gaussian shape of the deep slope indicates the migration of radiocesium into the depths of the sediments, and this process is significantly enhanced in some places due to bioturbation caused by tench preparing for hibernation. The exponential shape of the deep slope is typical for sediments in which in winter, in the presence of an ice cover on the lake, thermodynamic mixing occurs in the surface layer caused by the effects of pore water buoyancy. In these sediments, radiocesium dissolved in the pore fluid migrates upwards into the near-bottom water, becoming a source of secondary pollution of the water column. In winter, the presence of such a process is easily determined by the emergence of a layered structure of the water column in the lake and the temperatures of the near-bottom waters exceeding 4 °C. In this case, each layer is characterized by constant standard water parameters (temperature, conductivity, concentrations of oxygen, and trace elements). Complex forms of the deep slope of the vertical profile of radiocesium activity concentrations, combining elements of the exponential and Gaussian forms, indicate the episodic presence of both migration mechanisms.A method is proposed for identifying sediments that are a source of secondary pollution of lake waters by estimating the differences between the normalized logarithms of the radiocesium activity concentrations of the deep slopes (below the maximum concentrations) of its vertical profiles in the sediments of the studied samples and the sample of the carbonate barrier sediments, which were discovered in the shallow part of Lake Juodis in 2003.