Current Contamination Levels Research Articles

Microplastics in dairy products and human breast milk: Contamination status and greenness analysis of available analytical methods

The prevalence of microplastics (MPs) in food items is of significant concern due to their potential to cause various human health issues when ingested. Milk and dairy products are widely consumed for their nutritional value and have been found to contain MPs, as evidenced by numerous research studies. This review paper examines the current contamination levels of MPs in dairy products and breast milk, as well as evaluates the environmental impact of the analytical methods used for MPs analysis. The highest contamination levels in dairy products and human breast milk have been found up to 2590 MPs/L. Hence policymakers should enforce stringent regulations to ensure food quality. Additionally, it has been noted that existing analytical methods for detecting MPs in dairy products often fail to adhere to the principles of green analytical chemistry, with many scorings below 0.58 on the AGREE scale. These findings emphasize the urgent necessity for the development of rapid and green analysis methods for detecting MPs in dairy products and breast milk.

Use of lichens as bioindicators of contamination by agrochemicals and metals.

The presence or absence of lichens serves as an indicator of the condition of an ecosystem and the degree to which it is contaminated by various agents, such as agrochemicals and metals. Evaluating the use of lichens as bioindicators of agrochemical contamination could provide a more comprehensive perspective of current contamination levels. Monitoring was conducted over a 4-month period in two study areas: one was a well-conserved area contaminated by metals, and the other was an area surrounded by agricultural crops contaminated by agrochemicals. Data on the presence and abundance of lichens in each study area were recorded at 10 monitoring points, a procedure that was repeated 16 times (every 15days), and concentrations of heavy metals and "organophosphate" agrochemicals in the lichens collected were measured by means of Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-OES) and Gas Chromatography (GC), respectively. Generalized linear mixed models were used to assess abundance and richness, while general linear mixed models were used to attain Shannon diversity and Simpson dominance indices. Moreover, a multivariate analysis was performed in order to compare the lichen communities in both areas. The results indicated differences between the area contaminated by metals and that contaminated by agrochemicals in terms of abundance and Simpson's dominance index, while no differences were found in the case of the richness and diversity models. The PERMANOVA analysis additionally showed differences between the lichen communities in the two areas. The results also demonstrated that Canoparmelia caroliniana bioaccumulated metals in both areas. The levels of barium, cadmium, and sodium were higher in the area contaminated by metals, while concentrations of chromium and copper were higher in the area contaminated by agrochemicals. Finally, the concentrations of agrochemicals were higher in the area contaminated by agrochemicals and included toxic substances such as Methylparathion and Parathion, which are prohibited in Ecuador. In conclusion, this research underscores the importance of lichens as precise indicators of environmental health and contamination by agrochemicals and metals.

Comparison between the Baltic Sea and Irish Sea level of Cs-137 contamination on benthic, demersal and pelagic fish species

The Irish Sea and the Baltic Sea are nowadays still the two most Cs-137 contaminated Seas worldwide. However, the origins of this contaminations are completely different. While the Baltic Sea was unintentionally contaminated due to global fallout after the accident in the Chernobyl nuclear powerplant in 1986, the Irish sea was intentionally used for low level liquid radioactive waste discharges from the Sellafield nuclear reprocessing facility (called Windscale until 1981) between the 1950s and 1990s. Nowadays, more than 30 years later, it is still possible to detect these contaminations in fish, water and sediments of both seas. Since fish are an important part of the human diet, monitoring Cs-137 levels in fish is essential for assessing the potential radiation exposure to humans. In 2019 and 2020 two surveys were dedicated to study the current levels of radioactive contamination in fish species from both Seas. During both surveys, fish samples were collected and analysed by gamma spectrometry later on. The results show that the average Cs-137 activity in benthic, demersal and pelagic fish species from the Baltic Sea are 2.7, 4.6 and 4.2, respectively, times higher than the corresponding values of the Irish Sea. Based on this and two other comparisons, it is concluded that the Baltic Sea is the most contaminated with Cs-137.

Occurrence differences of hexachlorobutadiene and chlorobenzenes in road dust and roadside soil media in an industrial and residential mixed area in Eastern China

The road dust and roadside soil can act as both sinks and sources of hexachlorobutadiene (HCBD) and chlorobenzenes (CBzs), but comparative research on these two adjacent media is extremely limited. In this study, HCBD and CBzs were simultaneously analyzed in road dust and roadside soil samples from an area containing both industrial factories and residential communities in Eastern China. The road dust there was found to have 2–6 times higher contents of HCBD (mean 1.14 ng/g, maximum 6.44 ng/g) and ∑Cl3-Cl6CBzs (22.8 ng/g, 90.6 ng/g) than those in the roadside soil. The spatial distributions of HCBD and CBzs in road dusts were affected by various types of sources, showing no significant discrepancy among the sites. On the contrast, HCBD and CBzs contamination in roadside soils occurring near several factories were strongly correlated to their industrial point sources. Risk assessments showed, at current contamination levels in the road dust and roadside soil, HCBD and CBzs are not likely to induce carcinogenic or non-carcinogenic risks to residents in the studied area. Nevertheless, road dust ingestion, as the major exposure pathway of HCBD and CBzs, should be avoided to reduce the exposure risk. These findings based on the contamination differences between two media provide a new perspective and evidence for screening important sources and exposure pathway of HCBD and CBzs, which would be helpful to their source identification and risk control.

Глобальное загрязнение территории Южной Якутии Cs-137 и дозы облучения населения

The aim of the work is to estimate the radioactivity of Cs-137 in the soils of South Yakutia and to calculate the dose of internal irradiation of a critical group of people caused by the consumption of local foods containing radionuclide. An assessment of the radioactive contamination of the soil cover of South Yakutia showed that the radioactivity of Cs-137 in the soils of eluvial landscapes varies between 714 and 1,665 Bq/m2 and is commensurate with the radioactivity of Cs-137 in the soils of the Primorsky Krai, the Western Siberia and the Kola Peninsula. The present soil contamination levels of Cs-137, compared to the 2003 data, have been reduced on average by half due to radioactive decay of the radionuclide, the soil deepening and removal with surface water and vegetation. At present time there is no appreciable additional input of Cs-137 from the atmosphere to the soil cover of automorphic taiga landscapes in the South Yakutia. The specific activity of Cs-137 in watershed soils and river floodplains is low and corresponds to the background level of global pollution. The vertical distribution of Cs-137 over the soil profile of eluvial landscapes is realized on regressive-cumulative and eluvial-illuvial types. In soil profiles of hydromorphic landscapes Cs-137 is distributed, without any clear patterns, which is a consequence of the impact of alluvial processes. Calculations showed that at the current level of contamination of local foodstuffs, the annual effective dose of internal exposure of a critical population group from this radionuclide is 87 times less than the annual dose limit for the Russian population.

Multi-residue detection of antibiotics in migratory goat milk and human health risk assessment in Western Himalayan region, India

Occurrence of antibiotics in animal sourced foods not only affects economy but also poses potential health risks. The present study aimed to validate simultaneous detection of amoxicillin, penicillin – G and enrofloxacin in raw migratory goat milk (N = 223) by HPLC-DAD and assess human health risks in Western Himalayan region, India. The analytical method was found to be linear (R2 > 0.99), accurate (recoveries > 80 %), precise (RSD < 10 %), and sensitive (CCα, 0.92–1.61 ng/mL) with LOQ values well below the MRLs. Antibiotic residues were detected in 11 (4.9 %) samples, and 9/11 (81.8 %) samples had levels above MRLs. Human health risk assessments based on comparison of estimated daily intakes with acceptable daily intakes of antibiotics revealed that there are no acute health risks to adults and children at current levels of contamination. However, % contribution to ADI for enrofloxacin and penicillin-G were significantly higher in children. Therefore, keeping in view, availability and routine consumption of goat milk especially by families of nomadic pastoralists in Himalayan region, children may be at a greater risk than adults. Hence, the present study highlights the need for monitoring of goat milk for contaminants, and education of nomadic pastoralists to meet food safety standards and for protection of human health.

Establishing the extent of pesticide contamination in Irish agricultural soils

To establish meaningful and sustainable policy directives for sustainable pesticide use in agriculture, baseline knowledge of pesticide levels in soils is required. To address this, five pesticides and one metabolite widely used in Irish agriculture and five neonicotinoid compounds pesticides were screened from soils from 25 fields. These sites represented a diversity of soil and land use types. Prothioconazole was detected in 16 of the 18 sites where it had been recently applied, with the highest maximum concentration quantified of 46 μg/kg. However, a week after application only four fields had prothioconazole concentrations above the limit of quantification (LOQ). Fluroxypyr was applied in 11 sites but was not detected above LOQ. Glyphosate and AMPA were not detected. Interestingly, neonicotinoids were detected in 96% of all sampling sites, even though they were not reported as recently applied. Excluding neonicotinoids, 60% of sites were found to contain pesticide residues of compounds that were not previously applied, with boscalid and azoxystrobin detected in 15 of the 25 sites sampled. The total number of pesticides detected in Irish soils were significantly negatively correlated with clay fraction, while average pesticide concentrations were significantly positively correlated with log Kow values. 17 fields were found to have total pesticide concentrations in excess of 0.5 μg/kg, even when recently applied pesticides were removed from calculations. Theoretical consideration of quantified pesticides determined that azoxystrobin has high leaching risk, while boscalid, which was detected but not applied, has an accumulation risk. This information provides insight into the current level of pesticide contamination in Irish agricultural soil and contributes to the European-level effort to understand potential impacts of pesticide contamination in soil.

Risk assessment of human Hg exposure through consumption of fishery products in Ceará state, northeastern Brazil

The contamination of fish and aquaculture products may prove an obstacle to achieve the economic potential of the fishery sector worldwide. Seafood is a key source of Hg exposure to human consumers. Thus, it is necessary to monitor current contamination levels and formulate future scenarios of exposure to pollutants as supporting measures to improve, in the short and medium term, the sustainability of the fishing sector and guarantee food safety. In the short term, players in the private sector and governmental agencies need to provide up-to-date production data and to follow international recommendations, as it relates to seafood quality and sustainable production chains. Here, we provide an assessment of the fishery production in Ceará State, Brazil, and synthetize the present knowledge on Hg concentrations in fisheries and aquaculture products associated with their relative economic and consumers' diet relevance. The present assessment serves as a model study to produce a regionalized inventory of Hg concentrations in accordance with the national and international food safety guides and to estimate the risk of exposure to Hg of human populations through fisheries consumption. We show that legal Hg limits does not represent safe consumption levels, as exposure risk is a combined effect of trophic level, a proxy of Hg concentrations, consumption rates, and consumer age/weigh group. Most seafood species in Ceará have no restriction to human consumption, with a few exceptions. Children at a subsistence level mainly consuming fish are at most exposure risk. The overall information is graphically presented aiming to increase public perception on the theme and proposition of mitigating actions by the respective stakeholders.

Оцінка радіоекологічної ситуації для території природного заповідника «Древлянський» станом на 2023 р.

Technological methods for preparing geospatial data for assessing the radioecological situation and visualizing the results using geographic information system (GIS) software packages are presented in the article. The current levels of soil l37Cs contamination density within the grid of forest quarters of the reserve are given. The article emphasizes that the current levels of radiation contamination in the reserve have an irregular distribution. In this work, the procedure for data preparation was developed and technological methods were tested to assess the current state of the radioactively contaminated territory by forest quarters. The interpolation method was used to eliminate unevenness in the mapping layer of the source data. Radioecological zoning of the territory based on the density of soil contamination with l37Cs for 2023 was carried out to determine the suitability of the territory for the implementation of forest protection measures. Critical areas that generate hazardous levels of dose load for the employees of the Reserve were identified on the maps. The spatial distribution of forest fallout density was calculated. The spatial distribution of radiation contamination of timber and flammable fuel material within the forest quarters of the reserve was estimated. The analysis of the current radioecological situation for the territory of the Drevlians Reserve showed the effectiveness of using modern ArcGIS and MapInfo software packages. Such software combines the following capabilities: preparation of information matrices for calculations and interpolation, in case of limited input data, grouping and classification by values, formation of thematic data sets for storage and further display of results on map schemes.

ОЦІНКА МОЖЛИВОСТІ РЕГУЛЮВАННЯ ВОДНОГО РЕЖИМУ ОКРЕМИХ ТЕРИТОРІЙ ЧОРНОБИЛЬСЬКОЇ ЗОНИ ВІДЧУЖЕННЯ

The characteristics of the natural features of the Chernobyl Exclusion Zone (CEZ), in particular the nature of the relief, soil cover, main plant groups, and landscape characteristics, are provided. The hydrographic network of the region is detailed, represented by rivers, lakes, ponds, dams of the Pripyat and Uzh rivers, the reservoir of the Kyiv HPP, reclamation channels, water mirrors in front of filtration dams. It was noted that the main processes that form the current level of radioactive contamination of water systems in the CEZ are natural processes of radioactive decay, vertical sinking and geochemical fixation of radionuclides. Analysis of water pollution monitoring data in rivers and canals of the exclusion zone shows that by regulating water levels in most areas of the catchment areas of the CEZ, it is impossible to significantly influence the reduction of water pollution in them compared to the effects of their natural self-purification. Therefore, it is impractical to continue large-scale works on water flow regulation by hydrotechnical structures in order to minimize the removal of radioactive substances beyond the exclusion zone. It is advisable to leave in operation only those systems that allow maintaining increased moisture in peatlands, reducing the risks of fires. The studies carried out on the reclamation system “Buryakivka” in the basin of the Sakhan River, as an experimental training ground for the regulation of the regime of floodplains of the CEZ, are covered in detail. The use of the method of remote sensing of the Earth (DSS) to control the water regime and monitor the transformation of reclamation systems into wetlands is substantiated. In particular, spectral analysis of image pixels in different parts of the spectrum using vegetation indices. A positive nature protection effect from the increase in the area of wetlands in the Exclusion Zone was noted in the context of the prospects of climate change and in the context of the probability of increasing cases of dry periods in the territory of Polissia.

Geochemical distribution and environmental risk assessment of trace metals in groundwater released from e-waste management activities in Lahore, Pakistan.

Non-sustainable e-waste recycling and dumping activities release trace metals into the ambient environment where they may threaten the biological communities and human health. A total of 45 groundwater and 21 leachate samples were collected from seven recycling, seven dumping, and one reference site in Lahore, Pakistan, and analyzed for Cu, Pb, Zn, Cd, Mn, and Fe in atomic absorption spectrophotometer. Comparing the results with the World Health Organization (WHO) standards of drinking water, only the concentrations of Cu, Zn, Mn, and Fe at all sites were found to be within the permissible limits, i.e., 2, 3, 0.5, and 1mg/L, respectively. In leachates, only Cd and Mn at one site (0.204 and 8.636mg/L, respectively) exceeded the allowable limits of National Environmental Quality Standards of Municipal and Liquid industrial effluents. Geo-accumulation index, contamination factor, contamination degree, and pollution load index values showed no to moderate contamination. The ecological risk index did not exceed 150, depicting low risk to nearby biological communities. The non-carcinogenic health risk assessment showed a hazard index value greater than 1 at all sites for children (2.04) and adults (1.52), with Pb being the major contributor to adverse health impacts via ingestion and dermal route. Children (1.21 × 10-4) were at a more significant threat of carcinogenic risk from Pb and Cd as compared to adults (8.10 × 10-5). Therefore, there is a dire need to introduce sustainable e-waste recycling and managing techniques to reduce further groundwater contamination via the percolation of trace metals and to reduce the current contamination level.

English

Maize (Zea mays) is the staple food for the majority of people in Tanzania which plays a key role in subsistence and a cash crop among actors of the maize value chain. Environmental factors such as soil contamination by fungi, water stress, warm and humid conditions are among several factors contributing to fungal growth and aflatoxins contamination in maize, leading to significant economic loss, reduced household income, health problems to humans and animals and interferes with food security to communities. Structured questionnaires were used to collect information on awareness associated with aflatoxin contamination in maize from 160 smallholder farmers, 160 consumers and 60 traders in Kondoa and Chemba districts in Dodoma Region. A total of 90 maize samples (40 from smallholder farmers, 30 from consumers and 20 from traders) were analyzed for AFB1 using immuno-affinity high-performance liquid chromatography (HPLC) type Agilent Technologies 1200 serial. Data were statistically analyzed to assess awareness levels among maize main stakeholder and to check the current levels of aflatoxins B1 contamination in the study community. AFB1 was detected in five samples. About 3.3% of the contaminated maize had AFB1 levels above TBS acceptable levels (5 &micro;g/kg). The highest mean concentration of AFB1 was in maize samples taken from traders with a mean of 9.88&plusmn;5.904 &micro;g/kg. The majority 56% of smallholder farmers and 52% of traders were aware of aflatoxins contamination and associated health effects on animals and humans. However, 74% of consumers were unaware of aflatoxins contamination in maize. The levels of contamination are low in the sample taken along maize value chain. An effective and broad awareness programme for community especially consumers on good management for prevention of aflatoxins contamination is necessary, as maize is the most consumed grain in the study area.&nbsp; &nbsp; Key words: Aflatoxins contamination, smallholder farmers, consumers.

Desorption and Migration Behavior of Beryllium from Contaminated Soils: Insights for Risk-Based Management.

Factors influencing the desorption, distribution, and vertical migration behavior of Be in contaminated soils are not fully understood. This study examined the desorption and migration of Be in a soil profile from a legacy radioactive waste disposal site using different batch leaching [monofilled waste extraction procedure (MWEP); synthetic precipitation leaching procedure (SPLP); simulated acid rain solution (SARS); and toxicity characteristic leaching procedure] and sequential leaching [community bureau of reference (BCR)] methods for insights relevant to the application of risk-based management. The results showed that Be desorption was higher in the presence of organic than the inorganic leachate composition (MWEP < SPLP < SARS < TCLP < BCR first-step). The desorption followed three diffusion control mechanisms, which resulted in three desorption rate constant estimates of 157, 87.1, and 40.4 Be/kg.h0.5, and the estimated desorption maximum was 556 μg/kg. The desorption process was, spontaneous (ΔG > 0), enthalpically and entropically influenced. Increasing the incubation period and heat treatment resulted in a decrease of Be desorption and migration. The soil clay content and pH were the primary factors influencing Be desorption, and the results suggested that Be was desorbed from metal oxyhydroxides and surfaces of silicates (e.g., reactive surfaces of clay minerals), organic matters, and soil pores. Because of high Kd values, the mobility of Be was limited, and no exceedances of ecological or human health risk index or guidelines were determined for the current contamination levels at the site. However, Be released from the waste trenches has the ongoing potential to increase Be concentration in the soil.

Potentially Toxic Element Contaminations and Lead Isotopic Fingerprinting in Soils and Sediments from a Historical Gold Mining Site.

Lead (Pb) isotopes have been widely used to identify and quantify Pb contamination in the environment. Here, the Pb isotopes, as well as the current contamination levels of Cu, Pb, Zn, Cr, Ni, Cd, As, and Hg, were investigated in soil and sediment from the historical gold mining area upstream of Miyun Reservoir, Beijing, China. The sediment had higher 206Pb/207Pb ratios (1.137 ± 0.0111) than unpolluted soil did (1.167 ± 0.0029), while the soil samples inside the mining area were much more variable (1.121 ± 0.0175). The mean concentrations (soil/sediment in mg·kg−1) of Pb (2470/42.5), Zn (181/113), Cu (199/36.7), Cr (117/68.8), Ni (40.4/28.9), Cd (0.791/0.336), As (8.52/5.10), and Hg (0.168/0.000343) characterized the soil/sediment of the studied area with mean Igeo values of the potentially toxic element (PTE) ranging from −4.71 to 9.59 for soil and from −3.39 to 2.43 for sediment. Meanwhile, principal component analysis (PCA) and hierarchical cluster analysis (HCA) coupled with Pearson’s correlation coefficient among PTEs indicated that the major source of the Cu, Zn, Pb, and Cd contamination was likely the mining activities. Evidence from Pb isotopic fingerprinting and a binary mixing model further confirmed that Pb contamination in soil and sediment came from mixed sources that are dominated by mining activity. These results highlight the persistence of PTE contamination in the historical mining site and the usefulness of Pb isotopes combined with multivariate statistical analysis to quantify contamination from mining activities.

СЕЗОННЫЕ ИЗМЕНЕНИЯ СОДЕРЖАНИЯ ЧАСТИЦ МИКРОПЛАСТИКА В ПЕСКАХ ПРИБОЙНОЙ ЗОНЫ ПЛЯЖА

The paper considers the seasonal dynamics of the content of microplastic particles with a size from 0.5 to 5 mm in the sands of the surf zone of the Vistula Spit (the Baltic Sea). Microplastic particles are classified by size and color. The results are compared with the data for the Curonian Spit. It is concluded that the level of contamination with small microplastics (0.5–2 mm) of the sands of the swash zone can be used as a "background" value for the entire region and during all seasons of the year. The current level of sand contamination in the wave swash zone in the South-Eastern Baltic by small microplastic particles (0.5–2 mm) is 30–60 pieces per kg of dry weight throughout the year, while more than 90% are fibers.

Long-term dynamics of radionuclide contamination formation in the industrial іchthyofauna of the Kaniv Reservoir

The aim the study is to determine the temporal parameters of the long-lived radionuclides specific activity decrease in the commercial fish species of the Kaniv Reservoir for the period 1987–2021. Rutilus rutilus, Scardinius erythrophthalmus, Blissa bjoerkna, Abramis brama, Pelecus cultratus (peaceful species) and Esox lucius, Stizostedion lucioperca (carnivorous species) were selected in the middle and lower parts of the reservoir in January 2021 to determine the current levels of radioactive contamination in the representatives of the commercial ichthyofauna of the Kaniv Reservoir. The specific activity of 90Sr and 137Cs was determined in the entire body of fish by conventional radiochemical and gamma-spectrometric methods. The analysis of the dynamic characteristics of the radionuclides content in the representatives of the reservoir ichthyofauna was carried out on the basis of the results of studies of 90Sr and 137Cs content in fish during 1987–2012 and their specific activity in the body in 2021. In 2021, the average specific activity of 90Sr in fish was 0.6–1.6 Bq/kg, 137Cs - 2.4–13.2 Bq/kg. According to the results of previous studies, the average specific content of 90Sr in the fish of the Kaniv Reservoir decreased by approximately 6.5 times - from 60 ± 30 to 9 ± 3 Bq / kg during 1987-1993, and by 2003 it decreased by another 5 times up to 1.8 ± 0.8 Bq / kg and did not exceed the values recorded in freshwater fish in Ukraine before the Chernobyl accident in 1979–1985. Consequently, during the period of 2003–2021 the levels of 90Sr content in fish from the Kaniv Reservoir remained virtually unchanged. Based on the data on 137Cs accumulation in various feeding types fish in the Kaniv Reservoir, time parameters describing a decrease in the element specific activity were determined. During 1987–2021 the rate of decrease in 137Cs content in peaceful and predatory fish did not differ significantly and amounted to 0.10 ± 0.01 year-1, the period of effective half-decrease was 6.7 ± 0.7 years. Analysis of long-term data made it possible to distinguish 2 periods during which the specific activity of 137Cs in the fish organism decreased at different rates. In 1987-2004, 137Cs content levels in peaceful fish decreased from 70 ± 22 to 6.1 ± 2.2 Bq/kg, in carnivorous species - from 202 ± 41 to 19.8 ± 7.6 B/ kg, i.e. approximately by 10–11 times, which corresponds to a half-decrease of about 6 years. In 2004–2021 the element content in peaceful fish decreased to 2.9 ± 0.7 Bq/kg, in predatory fish - to 7.3 ± 4.1 Bq/kg, that is, by another 2–3 times, which corresponds to a half-decrease of 12 ± 3 years. Thus, it was found that the rate of decrease in 137Cs specific activity in fish slows down over time. The obtained parameters will make it possible to predict with a high degree of accuracy the dynamics of the radionuclide contamination formation in ichthyofauna in the event of artificial radionuclides entering aquatic ecosystems as a result of emergency situations. Key words: Kaniv Reservoir, fish, radionuclides, longterm dynamics, rate of decrease.

Heavy metals in soil, plants, and associated risk on grazing ruminants in the vicinity of Cu-Ni mine in Selebi-Phikwe, Botswana.

The impact of BCL Cu-Ni mines on the surrounding environment has indicated high levels of heavy metal contamination in soil and some plant species. A comprehensive assessment of heavy metal concentration in plants, heavy metal concentration and availability in soils, and the estimates of risk associated with grazing animals in the area are presented. Exhaustive quantification of heavy metal contents in 82 plant samples revealed that some plants such as Boscia albitrunca and Boscia foetida are suitable for multi-metal phytoextraction, and others can accumulate one or two of the metals in soils or tolerate high levels of contamination. Current levels of soil contamination were manifested by acidification and high electrical conductivity, high contamination factor, and a pollution index between 8.31 and 10.79. The amount of exchangeable fractions of metals was higher than ordinary soils which is attributed to the high solubility of deposited materials on the soil surfaces. Daily intake estimates showed a possible risk associated with Pb and Cu contamination among grazing animals in the study area. Overall, the information has identified potential plants or combination of plants that could be utilized for the rehabilitation of the study area through phytoremediation. In addition, the estimates of the daily intake of the minerals due to consumption of plants in the vicinity of the BCL mines warrant for evaluation of the actual levels of heavy metals in grazing animals near the study area and in other mining areas in Botswana.

Threshold dose rates for the cytogenetic effects in crested hairgrass populations from the Semipalatinsk nuclear test site, Kazakhstan

An assessment of cytogenetic effects in crested hairgrass (Koeleria gracilis Pers.) populations was carried out within the Semipalatinsk nuclear test site (Kazakhstan) where combat radioactive substances were tested in 1953–1957. Current levels of radioactive contamination within this site are varied by orders of magnitude, while soil characteristics and heavy metal pollution are similar. The main contribution to the absorbed by plants doses at this site was caused by incorporated 90Sr. The frequency of cytogenetic alterations in crested hairgrass was investigated in a wide range of doses (10−4–13 Gy/growing season) at 100 sampling points. For the first time in the field conditions the shape of the cytogenetic effects - dose rate relationship was evaluated with acceptable accuracy and found to be nonlinear. The frequency of aberrant cells remained practically unchanged up to 49 µGy/h. Exceeding the threshold dose rate lead to a steep increase in the aberrant cells frequency from less than 2% up to 16%. The main contribution to the cytogenetic effects was made by double bridges and fragments. Breakpoints for other types of cytogenetic alterations were also evaluated (7 µGy/h for single fragments and bridges; 74 for double fragments and bridges; 81 for mitotic abnormalities).

Obstacles and ways of forming effective protection of rice crops from weeds

Goal. Assessment of the current level of soil contamination in rice checks with weed seeds and determination of the reasons for insufficient efficiency of herbicide application to ensure high yields of rice sown in the south of our country. Research methodology: Field small-site experiments were conducted in crops (rice checks) of the Institute of Rice of NAAS of Ukraine (Antonivka village, Skadovsk district, Kherson region). The size of the sown experimental plot is 66 m2, the accounting area is 50 m2. The experiments were repeated 4 times. Placement of plots is regular in two tiers. Accounting and analysis were performed in accordance with the specifics of the requirements «Methods of testing and application of pesticides» edited by Professor S.O. Tribel, and Methods of research in beet growing. The level of yield of rice crops was determined by continuous harvesting of accounting plots on all repetitions of variants by a special selection combine «Sampo-2000» with the subsequent conversion into t/ha. Results. Washing of soil samples from rice checks and analysis of washed seeds and organs of vegetative reproduction revealed that the largest stocks of live seeds are present in the horizon 0—10 cm, and average 1310.0 pieces/ m2 of rooster millet. The total stock of seeds of different types of weeds that retained the ability to germinate in the soil was 12987.8 pieces/ m2. The number of weed seedlings in weed control crops (option 1) averaged 894.8 pcs/m2. In crops of option 2 after application of soil herbicide Kommand 48, KE (Clomazon, 480 g/l) with a concentration of working solution — 0.25%, at the rate of consumption of 0.5 l/ha before germination, the number of weed germs decreased to 550.5 pcs/ha or by 38.5%. Spraying of crops of rice of sowing in the period of formation — 3 leaves with a norm of expenses of working liquid of 200 l/hectare, herbicide Topshot, 113 OD of m.d. normal sow 3.0 l/ha with a concentration of working solution — 1.5%, further reduced the number of weeds in crops. The overall decrease in the number of weed plants in rice crops averaged 90.2%. Seedlings of acute plague died by 91.0%, rooster millet by 97.1%, bitter gourd by 96.3%. At the same time, the seedlings of Korsakov’s monochoria died out by 79.4% of the compact reed tuber by 77.1%, and the spreading plague by 76.2%. In crops of sown rice, 59.5 pcs/ m2 of weed plants of different species still remained to grow. Surviving plants were formed in rice crops on average 1452 g/m2 weight or 39.5% of its maximum volume in the experiments (option 1). The main part of the mass of weed plants was monocotyledonous species — 73.9%. The yield of rice crops was 5.12 t/ha or 44.8% of the maximum in the experiments (option 3). Conclusions: Systems of measures to protect rice crops should be aimed primarily at reliable and systematic control of seedlings and seedlings of the most numerous and problematic weed species: members of the botanical families Osokov and Tonkonogov.

A comparison of the concentrations of heavy metals in modern and medieval shells of swollen river mussels (Unio tumidus) from the Szczecin Lagoon, SW Baltic basin

The shells of mussels, live-collected bivalves or during archaeological excavations, can be used as bioindicators of current and historical levels of heavy metal contamination. In this study, we examined the shells of Unio tumidus, commonly found in the Baltic Sea region, and determined the concentrations of Zn, Cu, Fe, Pb, Ni, and Cd in samples from the 10th, 11th, and 21st century from the area of the Szczecin Lagoon. The average levels of heavy metals (in μg g−1 dry weight) in the shells from the Middle Ages were: 137.5 (Fe), 3.87 (Zn), 0.789 (Cu), 0.012 (Pb), 0.047 (Ni), and 0.0009 (Cd). Shells from the 21st century were significantly (P<0.05) more abundant in Fe, Cu, Ni, Pb, and Cd (rates of increase: 1.96×, 3.54×, 2.71×, 2.08×, and 3.55×, respectively) than shells from the Middle Ages. These results reflect contemporary anthropogenic pollution of the environment with heavy metals and confirm the possibility of using U. tumidus shells in the assessment of heavy metal pollution levels.