Total Heavy Metal Concentrations Research Articles

Assessment of water quality and heavy metal contamination in ballast water: Implications for marine ecosystems and human health

The global menace of non-compliance with ballast water management poses a pressing environmental threat, as it facilitates the transfer of harmful organisms and sediment contaminants. This study investigates the environmental impact of ballast water discharged by ships, focusing on water quality and heavy metal concentrations. The release of ballast water, often containing elevated levels of heavy metals like mercury, lead, and cadmium, poses a significant threat to marine ecosystems. The research, involving water sample collection from ten different vessels across various countries, assesses physicochemical parameters and heavy metal concentrations. Results indicate variations in temperature, turbidity, conductivity, dissolved oxygen, and pH levels among samples. Turbidity values surpassing WHO limits suggest potential anthropogenic pollution. The study identifies significant differences in pH values, potentially influencing microbial populations. Total dissolved solids and total suspended solids values vary, affecting the distribution of potential pathogens. The results reveal varying total concentrations of heavy metals (mg/L) in the following decreasing order: SA>SE>SF>SB>SC>SD>SH>SI>SG>SJ(6.07 >4.95 > 2.07 > 1.59>0.24>1.22>0.09>0.04>0.03>0.01). The highest concentration of heavy metals is recorded for iron (SA= 5.78), zinc (mg/L) (SB = 1.36, SE = 1.30, and SF = 1.35) and lead (Pb) (SE = 2.39). The elevated iron levels in vessels from SA are potentially linked to corrosion processes. Cadmium, lead, and nickel were not detected, except for lead in the sample from SE. Copper concentrations were aligned with EU standards in the vessels. Proper ballast water management is vital for monitoring water qualities, preventing environmental spread of heavy metals, ensuring marine ecosystem health, and developing compliance strategies for ships docking in ports. Highlights Global shipping causes heavy metal pollution, affecting human and ecosystem health Physicochemical parameters variations suggest potential pollution and microbial impact Mercury, lead, and cadmium in ballast water (BW) pose threats to marine ecosystems Increased iron levels could be associated with corrosion processes Effective BW management is crucial for environmental conservation

Driving factors for distribution and transformation of heavy metals speciation in a zinc smelting site

Heavy metal pollution at an abandoned smelter pose a significant risk to environmental health. However, remediation strategies are constrained by inadequate knowledge of the polymetallic distribution, speciation patterns, and transformation factors at these sites. This study investigates the influence of soil minerals, heavy metal occurrence forms, and environmental factors on heavy metal migration behaviors and speciation transformations. X-ray diffraction analysis revealed that the minerals associated with heavy metals are mainly hematite, franklinite, sphalerite, and galena. Sequential extraction results suggest that lead and zinc are primarily present in the organic-sulfide fractions (F4) and residual form (F5) in the soil, accounting for over 70% of the total heavy metal content. Zinc displayed greater instability in carbonate-bound (16%) and exchangeable (2%) forms. The migration and diffusion patterns of heavy metals in the subsurface environment were visualized through the simulation of labile state heavy metals, demonstrating high congruence with groundwater pollution distribution patterns. The key environmental factors influencing heavy metal stable states (F4 and F5) were assessed by integrating random forest models and redundancy analysis. Primary factors facilitating Pb transformation into stable states were available phosphorus, clay content, depth, and soil organic matter. For Zn, the principal drivers were Mn oxides, soil organic matter, clay content, and inorganic sulfur ions. These findings enhance understanding of the distribution and transformation of heavy metal speciation and can provide valuable insights into controlling heavy metal pollution at non-ferrous smelting sites.

Prediction models for bioavailability of Cu and Zn during composting: Insights into machine learning

Bioavailability assessment of heavy metals in compost products is crucial for evaluating associated environmental risks. However, existing experimental methods are time-consuming and inefficient. The machine learning (ML) method has demonstrated excellent performance in predicting heavy metal fractions. In this study, based on the conventional physicochemical properties of 260 compost samples, including compost time, temperature, electrical conductivity (EC), pH, organic matter (OM), total phosphorus (TP), total nitrogen, and total heavy metal contents, back propagation neural network, gradient boosting regression, and random forest (RF) models were used to predict the dynamic changes in bioavailable fractions of Cu and Zn during composting. All three models could be used for effective prediction of the variation trend in bioavailable fractions of Cu and Zn; the RF model showed the best prediction performance, with the prediction level higher than that reported in related studies. Although the key factors affecting changes among fractions were different, OM, EC, and TP were important for the accurate prediction of bioavailable fractions of Cu and Zn. This study provides simple and efficient ML models for predicting bioavailable fractions of Cu and Zn during composting, and offers a rapid evaluation method for the safe application of compost products.

Dedicated microwave extraction allows uniform energy distribution to efficiently solubilize Ascophyllum nodosum

Considering the current transition to biobased carbon sources and the search for viable extraction procedures, the microwave-assisted solubilization of seaweed biomass was explored. Hereto, the brown North Sea native species Ascophyllum nodosum was processed using water as green extraction solvent. Response surface methodology was used to determine the best solubilization conditions towards maximizing the solubilization efficiency and minimizing the applied energy per mass of solubilized seaweed by varying (i) temperature, (ii) time and (iii) solid to liquid ratio (S/L). It was found that a temperature of 120 °C, a processing time of 15 min and a 1.03 w:v S/L are most suitable to achieve the pre-set criteria. Concurrently, mass balances were developed with respect to total lipid, polysaccharide, protein, mineral and heavy metal contents. Moreover, zeta potential measurements were performed to link the obtained values and the antimicrobial characteristics of the extracts. Finally, antimicrobial tests on S. aureus and E. coli were conducted and with results indicating up to 97 % inhibition of bacterial growth after 8 h, antimicrobial characteristics were indeed observed.

Unlocking critical nutritional potential: A comprehensive analysis of small indigenous fishes in Bangladesh and the development of ready-to-use fish products as balanced food

The study aimed to develop fish powder as a promising dietary supplement to combat inadequate nutrition. To achieve this goal, the study assessed the nutritional aspects, including proximate composition, mineral content, amino acid profile, and fatty acid profile, as well as the microbiological quality and heavy metal contents, of six small indigenous fish species. The protein content ranged from 57.73 % to 65.26 %, with G. chapra exhibiting the highest protein content (p < 0.001). In all fish powders, the mineral composition was found in the following order: Na > P > Ca > K> Mg > Fe > Mn > Zn. The results revealed significantly elevated levels of total essential amino acids in A. mola (227.20 mg/g, p < 0.001). The PUFA/SFA ratio (> 0.45) and ω-6/ω-3 fatty acids ratio (< 4.00) were generally optimal. The quality and safety of the fish products for human consumption were confirmed, as both the total colony count and heavy metal concentrations remained below the recommended threshold. All ready-to-use fish products, except A. mola, meet over 20 % of the daily nutritional needs for PLW, infants, and adults. Hence, these findings advocate the utilization of the studied fish species as a dietary supplement to address malnutrition.

Enrichment Characteristics and Ecological Risk Assessment of Heavy Metals in a Farmland System with High Geochemical Background in the Black Shale Region of Zhejiang, China

Soils derived from black shale enriched in heavy metals pose risks to the environment and human health. Eighty sets of soil–rice samples were collected in northwest Zhejiang, China. The results showed significant enrichment of As, Cd, Pb, and Zn in the studied soil. Sequential extraction data indicated that Cd had relatively high bioavailability. Thirty-four percent of the rice samples exceeded the heavy metal pollution thresholds of national food safety standards. A comprehensive evaluation of soil heavy metals using the potential ecological risk index (RI) revealed low-to-moderate-grade risk. Risk assessment code (RAC) levels decreased as follows: Cd &gt; Ni &gt; Zn &gt; Cr &gt; Cu &gt; Pb &gt; As &gt; Hg. The RAC of Cd was high and very high risk, whereas those of others were no or low risk. Cd was the major contributor to the environmental risk based on the total heavy metal concentration, toxicity, and chemical fractions. The health risk to the local populace was assessed using the method recommended by the USEPA. Local people may experience both non-carcinogenic and carcinogenic health risks, and children face greater health risks than adults. As, Cd, and Pb are the most significant contributors to non-carcinogenic health risks, and Cd is the main carcinogenic risk. In conclusion, special attention should be given to heavy metal pollution in black shale-derived soils.

Quarry soil and quarry stream water baseline level parameters around Chestedi Quarry, F.A.U.C. Golden Ltd Quarry, Fakunle Quarry and River Oyanmi in Igarra, Akoko Edo

The primary objective of this research was to investigate the initial levels of chemical parameters surrounding quarry operations in Igarra, Akoko-Edo, Edo State. Specifically, three prominent quarries (Chestedi, F.A.U.C. Golden Ltd, and Fakunle) were examined, along with the water of River Onyami flowing through these quarries from the Ojirami dam. Each quarry site yielded four soil samples collected at a various depth (between 0 – 15 cm) and different geographical coordinates, while four water samples were obtained from River Onyami. These samples underwent analysis for their physicochemical properties and the chemical speciation of Fe, Zn, Cu, Pb, Cr, and Mn. As Tessier et al. (1978) described, a sequential extraction method was employed to partition the heavy metals into five different fractions. Total concentrations of heavy metals in both soil and water samples were determined. The distribution of heavy metals in the soil exhibited the following order of accumulation: Fe &gt; Zn &gt; Mn &gt; Cu &gt; Pb &gt; Cr, whereas in water samples, the order was Fe &gt; Zn &gt; Cu &gt; Mn &gt; Pb &gt; Cr. Iron and zinc emerged as the predominant heavy metals in the soil, with iron within permissible limits but zinc, copper, manganese, lead, and chromium exceeding their respective limits. In the stream water, iron and lead surpassed their permissible limits, while Zn, Cu, Cr, and Mn remained below theirs. Comparative analysis against WHO, NIS DPR, and CCME maximum contamination/permissible limits was conducted for heavy metal concentrations and physicochemical properties in both soil and water samples. Mobility Factors (MF), Environmental Risk Factors (ERF), Contamination Factors (CF), Pollution Load Index (PLI), and Geoaccumulation Index (GI) were computed. Results from this study indicate that the soil is conducive to supporting growth and is nutrient-rich for various applications, while the water is suitable for irrigation and other domestic purposes.

DYNAMICS OF HEAVY METAL ACCUMULATION IN TROPHIC LEVELS OF FOREST ECOSYSTEMS

The aim of the study is to examine the accumulation of heavy metals (HMs) in trophic levels (soil, wood, tree leaves and fungi of various evolutionary origin) of forest ecosystems.&#x0D; Materials and Methods. The authors examined soil, wood, leaves and fungi in forests with different anthropogenic load intensity. The collecting grounds were selected according to forest management materials. In total, 26 grounds were examined. Sampling of soil and fungi of various trophic levels was carried out on different substrates, in different forest conditions and under different levels of technogenic impact. Leaf and wood samples were taken from phytopathogen-affected and healthy trees. Chemical sample analysis was carried out using a Kvant atomic absorption spectrophotometer.&#x0D; Results. The total heavy metal content in fungi is higher than in wood, but lower than in soil. The total heavy metal content in leaves of Norway maple affected by Rhytisma acerinum is higher compared to the leaves from heathy trees. Iron predominates among the heavy metals found in the fungi under consideration; cadmium content is minimal.&#x0D; Conclusion. The largest amount of accumulated heavy metals was found in the fruiting bodies of the facultative saprotroph, and the smallest amount was in the bodies of the facultative parasite. The forest type and growing conditions affect the heavy metal content in ecosystems.

Heavy metal pollution near an abandoned mercury-bearing waste recovery enterprise in southwestern China: Spatial distribution and its sources in soil and plants

The contribution of smelting of nonferrous metals to heavy metals in surface soil have become increasingly important over the past decade. In this study, the distribution of heavy metals around an abandoned mercury-bearing waste recovery enterprise were investigated. Soil (14) and plant (18) samples were collected in the surrounding area. The total concentration of heavy metals and methyl mercury content were measured by ICP-MS and HPLC-ICP-MS. The results show that the average contents of Cd, Cr, Pb, Hg and As in all soil samples are higher than the second-level values of Soil environmental quality-Risk control standard for soil contamination of development land (GB 36600-2018). Hg in the leaves ranged from 0.003 to 0.174 mg kg−1. Besides, the Pearson correlation analysis results indicate that Hg has a different environmental behavior compared to the other heavy metal under certain environmental or geographical conditions. But the mantel test statistical analysis results show that the Cr (P < 0.01), Cu, Pb, and Fe (P < 0.05) in the soil may have similar pollution sources with carbonate-bound mercury and iron-manganese oxide-bound mercury. The Hg concentrations show no correlation among plant leaves and soil, but significantly influenced by the distance and wind direction. These findings suggest that Hg in plant leaves may be derived from the deposition of atmospheric mercury from secondary mercury plant. The results will supplement those for relevant policy making for mercury-bearing waste recovery enterprises to improve urban environmental quality and human health.

Serpentine environment prevails over geographic distribution in shaping the genetic diversity of Medicago lupulina L.

Edaphic conditions of serpentine soils, naturally rich in heavy metals, act as a strong selection pressure that shapes specific metal-tolerant ecotypes. Medicago lupulina L. (black medick) is not only a widespread plant species that prefers calcareous and dry soil types but also grows at the borders of serpentine formations. It can also be found in waste and disturbed habitats. This is a species with reported phytoremediation potential, however, there is no published data regarding the impact of the environment on the genetic distribution of this species. The aim of our research was to explore how selection pressure of serpentine soils affects genetic diversity of M. lupulina and to test heavy-metal accumulation capacity of this species. Specimens of 11M. lupulina populations were collected from serpentine outcrops located in Central and Eastern Bosnia as well as from non-serpentine sites. Soil and plant samples were analyzed for the total contents of heavy metals using air-acetylene flame atomic absorption spectroscopy. Genetic diversity was analyzed using AFLP (Amplified Fragment Length Polymorphism) markers. Serpentine soils showed high nickel, cobalt, chromium and iron concentrations. Nickel and manganese concentrations in soil samples and plant material showed statistically significant correlation. Although plants in two populations show the ability to extract Ni, M. lupulina does not show hyperaccumulating properties. Despite severe selective pressure, genetic diversity in serpentine populations is not reduced. Analyses of intrapopulation and interpopulation genetic diversity showed significant genetic differentiation among populations which is not related to their geographic distance. Population from non-metalliferous soil showed clear separation from all other populations. Diversity data suggest that serpentine populations maintain genetic diversity by undetected mechanisms and that edaphic factors rather than geography influence genetic structure analyzed M. lupulina populations.

Effects of mild acid pre-treatment on the co-pyrolysis behaviour of biosolids and wheat straw

Co-pyrolysis of biosolids (BS) and wheat straw (WS), as well as their treated variants, was performed in a fluidised bed reactor at 500 ℃. Under mild acid pre-treatment conditions (3% H2SO4 and 25 ℃), demineralisation was the dominating effect of pre-treatment on BS, while it was hemicellulose hydrolysis for WS. Consequently, the co-pyrolysis of raw biosolids (RBS) or treated biosolids (TBS) with raw wheat straw (RWS) or treated wheat straw (TWS) had varying effects on product distribution and product compositions. The co-pyrolysis of RBS+RWS gave the lowest bio-oil yield (36.3 wt%) and highest gas yield (23.1 wt%). In contrast, the highest bio-oil yield (45.8 wt%) and lowest gas yield (14.4 wt%) occurred during the co-pyrolysis of TBS+TWS. The degree of synergy in product distribution was strongest in TBS+RWS followed by RBS+RWS and was weakest in TBS+TWS, demonstrating the catalytic effect of inherent minerals on organic matter devolatilisation and char cracking reactions during co-pyrolysis. Biosolids pre-treatment alone performed competitively with BS co-pyrolysis alone with respect to enhancement in biochar properties producing biochar having 15–18 MJ/kg calorific value, 43–51 wt% carbon content, 0.7–1.0 fuel ratio, ⁓30% organic matter retention, and 27–41 wt% ash content. However, combining BS co-pyrolysis and pre-treatment gave the lowest reduction in biochar total heavy metal concentration. Furthermore, bio-oil compositions were influenced by pre-treatment and/or co-pyrolysis, increasing the yield (area%) of phenols to 25.4%, furans to 24.8%, anhydrosugars to 7.8%, and aromatic hydrocarbons to 20.6%. Lastly, pre-treatment alone weakened gas production while co-pyrolysis combined with pre-treatment impacted the pyrolysis gas profile, switching between light hydrocarbons and carbon oxides (CO and CO2). Overall, co-pyrolysis and pre-treatment can each be a standalone strategy for enhancing BS pyrolysis; however, their combination produced greater synergy for generating high value products.

Heavy Metal Pollution in Soils near Ilesha Gold Mining Area, Nigeria

Background The discovery of extensive gold deposits has raised concerns about potential heavy metal contamination in waterways and adjacent soils, particularly in developing nations like Nigeria where environmental regulations may not be stringent enough. Objective A research study was conducted to assess the levels of heavy metals in surface soils (0 to 25 cm deep) across 30 sites within three selected areas (Epe, Igun, and Ijana) located in the gold mining region of Ilesha, Osun State Nigeria. Methods The study employed an atomic absorption spectrophotometer to measure the total concentrations of heavy metals, specifically arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn). Furthermore, the research encompassed an examination of various physicochemical properties of the soil samples, including organic matter content, pH levels, organic carbon content, calcium content, phosphorus levels, cation exchange capacity, and particle size distribution. Results Results showed a range mean concentration with standard deviation of As, Cd, Co, Cr, Cu, Ni, Pb and Zn of 1.0 – 7.1 ± 1.77 mg kg-1, 0.9 – 4.2 ± 0.84 mg kg-1, 1.0 – 6.0 ± 1.29 mg kg-1, 1.1 – 6.4 ± 1.57 mg kg-1, 2.90 – 20.9± 4.00 mg kg-1, 1.1 – 6.4 ±1.56 mg kg-1, 0.7 – 6.7 ±1.26 mg kg-1 and 11.7 – 70.7± 17.75 mg kg-1, respectively. The investigation of soils in three specific locations revealed significant contamination by heavy metals. However, it is worth noting that the concentrations of these metals fell below the established intervention levels outlined by environmental protection agencies such as the World Health Organization and the Food and Agriculture Organization. The distribution of heavy metals and their availability exhibited a direct correlation with the distance from the mining sites, spanning from 0 to 900 meters. Two critical factors influencing the concentration of heavy metals in these areas were identified as soil particle size, specifically the clay percentage, and pH levels. Conclusion Despite the presence of heavy metal pollution in the soils of Epe, Igun, and Ijana, they managed to maintain metal levels below the intervention thresholds set by environmental protection agencies, with the exception of cadmium (Cd).

Risk assessment of Cr, As, and Sb to aquatic communities at the water-sediment interface in the lower Yellow River, China, integrated with the Diffusive Gradients in Thin‐films technique

The dynamic concentrations of labile metals/metalloids, measured by the Diffusive Gradients in Thin-films (DGT) technique, can be used for evaluating the toxicity risk of heavy metals to aquatic organisms in sediments. In this study, the different potential risks of the three sediment compartments, overlying water (W), sediment- water interface (SWI) and sediment (S) were independently assessed by studying the concentrations of Cr, As, and Sb in the sediment and water from the lower Yellow River. Total concentrations of these elements and bioavailable concentrations, using DGTs, were explored and probabilistic risk assessment (PRA) based on a Monte Carlo model was performed. The results show that the total heavy metal concentrations in sediment and overlying water were spatially variable due to influences of natural geography and sediment distribution. The trace elements mean concentrations using DGT were 1.68, 1.69 and 0.73 μg·L−1 for Cr, 0.61, 0.51 and 0.39 μg·L−1 for As, and 0.78, 1.16, and 0.41 μg·L−1 for Sb in W, SWI and S, respectively. Among them, the DGT-labile concentration of As displayed a large spatial variability, indicating a close association with anthropogenic activities. The risk quotient (RQ) categories for single heavy metal toxicity demonstrated to be moderate risk for Cr and almost no risk for As and Sb. The combined biotoxicity probability assessment of the three heavy metals showed that they would cause almost no harmful effects to benthic organisms in the whole ecosystem of the Yellow River.

Selenium and Heavy Metals in Soil–Plant System in a Hydrogeochemical Province with High Selenium Content in Groundwater: A Case Study of the Lower Dniester Valley

The bioaccumulation of selenium (Se) and heavy metals (HMs) in plants is important because it can affect plant health and human nutrition. Recognizing the factors affecting Se accumulation in plants may have important implications for agricultural practices and human health in selenium-rich regions. The study primarily focused on the interactions between Se and HMs in the soil–plant system of the Lower Dniester Valley. Total concentrations of HMs (Cu, Mn, Zn) were determined by atomic absorption spectrometry, while Se concentrations were determined by a sensitive single-test-tube fluorometric method in solutions and extracts. Water-soluble Se (0.09 ± 0.03 mg·kg−1) in soils was 32.1% of the total Se (0.33 ± 0.13 mg·kg−1) and increased with the total rising Se content (r = 0.845). The results indicated that plants had a greater Zn accumulation capacity than that of the other HMs, suggesting its importance as a trace element for plant requirements. Se also had a high bioaccumulation rate. Se and Zn accumulation varied in different soil types, reflecting differences in bioavailability. In contrast, Mn and Cu showed low bioaccumulation, which varied with soil conditions and anthropogenic Cu pollution. Despite the Cu contamination of the soils in the investigated region, it can be inferred that the hydrogeochemical province with high Se content in groundwater has favorable conditions for Se mobilization in soils. The absence of antagonistic interactions with HMs in the soil–plant system contributes to the enhanced Se accumulation in plants in the Lower Dniester Valley. These results emphasize the complexity of the interactions between Se and HMs in the soil–plant system and their potential impact on agricultural practices.

ASSESSMENT OF HEAVY METALS ACCUMULATION IN PERENNIAL LEGUMES (WHITE CLOVER AND RED CLOVER) IN THE COPȘA MICĂ AREA, ROMANIA

The impact of heavy metals on perennial legumes, just like on other plant species, can be detrimental and has several ecological and agricultural implications. The ability of perennial legumes to fix atmospheric nitrogen through symbiotic interactions with nitrogen-fixing bacteria in their root nodules makes them a significant group of plants. The present study aims to evaluate the total concentration of heavy metals (cadmium, lead, copper, and zinc) in red and white clover plants harvested from grasslands located in heavily polluted areas (Copșa Mică, Axente Sever, Valea Viilor, Micăsasa and Târnava). White clover (Trifolium repens L.) recorded Cd content values between 0.06 - 3.53 mg/kg dry weight, Cu had values between 4.09 - 33.4 mg/kg dry weight, Pb content was between 0.18 - 4.77 mg/kg dry weight and Zn had values between 38 - 186 mg/kg dry weight. Regarding red clover (Trifolium pratense L.) the heavy metal content values were as follows: for Cd (0.08 - 3.38 mg/ kg d.w), for Cu (6.03 - 13.5 mg/kg d.w), for Pb (0.13 – 2.34 mg/kg d.w), for Zn (33.1 - 169 mg/kg d.w). Our results show that clover species harvested from grasslands in these geographical areas have high levels of heavy metals due to metallurgical activities. Grazing in these areas affected by heavy metal pollution can pose serious health problems for animals and later for humans through consumption of their products.

Assessment of Heavy Metal Pollution from Granite Quarrying in Akure, Nigeria

This study investigated the heavy metals pollution of granite quarrying activities in Akure, Ondo State, Nigeria. Three quarries and a control site were selected for this study. Plants and soil samples were collected at 0, 50, 100, 150 and 200 m away from the crushing points, while samples were collected away from roadside for control. Water samples were collected at just a point. Concentration of heavy metals in collected samples was determined using Buck Scientific Atomic Absorption Spectrophotometer model 210 VGP. The mean total heavy metal contents in C. odorata and P. purpurem collected within 0 to 200 m showed that Pb, Fe, Zn, Cr Co and Cd contents were above the WHO permissible limit while only Pb content (190.8, 299.20 and 208.80 ppm) and Fe (7559.50, 13386.50 and 19019.50 ppm for Dortmond, Ebenezer and Samchase quarries respectively) were above the permissible limit in soil samples. Elevated Pb, Fe, Cr, and Ni were recorded in water samples collected from quarry sites while values recorded for control sites falls within the permissible limit except for the lead concentration of 0.10 ppm as against the maximum concentration of 0.05 ppm set by WHO. Zn, Mn, Cd and and Cu were not detected in all water samples. Higher pH values were also recorded in soil and water samples from quarry sites. This study has shown that quarrying introduces toxic heavy metals into nearby environment.

The effect of ascorbic acid and lemon juice on the extraction of metals from green tea, health risk assessment

The total heavy metal concentration (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) in green tea leaves and metals leached into tea infusions of pure water with the addition of ascorbic acid and lemon juice at various temperatures (70, 80, and 100 °C) and steeping times (3, 5, and 7 min), were determined. Metal concentrations were analyzed by atomic absorption spectrometry and the flame technique (FAAS). Mean total concentrations of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn were < LOD, <LOD, 0.198, 4.527, 67.51, 333.7, 2.588, <LOD, 10.23 μg/g, respectively. The highest percentage of extraction in different solutions was in the case of Mn (up to 100%). The risk for adults through consumption of tea was mainly contributed by Mn, and non-carcinogenic hazard quotient (HQ) was slightly higher than 1 when infusions were heated to 100 °C. High percentages of Ni were extracted in pure water compared to water with addition, regardless of tea steeping time, followed by Cu in pure water and water with lemon juice. Fe was poorly extracted in all applied solutions; the highest percentage of extraction (17.21%) was determined in lemon juice solutions of at 100 °C during a steeping time of 7 min.

Агроэкологическая характеристика черноземов Каменной степи: влияние растительных сообществ и распашки

Changes in soil carbon stocks have a significant impact on atmospheric CO2 concentrations and the global carbon balance. Despite the proven effectiveness of agroforestry in erosion control and prevention of soil fertility loss, there are many controversial data suggesting that the impact of afforestation on Chernozem soils should be further investigated. The Kamennaya Steppe site (arable land surrounded by shelterbelt forests) is a reference site for monitoring studies at the Voronezh Carbon Test Site, where the carbon balance of agro-ecosystems is being studied and the ecological role of shelterbelt forests in changing soil properties and carbon sequestration is being evaluated. The study was focused on the evaluation of agro-ecological characteristics and the impact of tillage on Chernozems of Kamennaya Steppe under different vegetation types. The study of the chemical properties of chernozems was carried out using classical chemical methods; the analysis of heavy metals was carried out using the voltampermetric method. Comprehensive agro-ecological evaluation showed that the studied Vorony-Calcic Chernozems had a high content of humus, which reached 7-8% in the upper horizons, enriched with mineral nutrition elements, and had favorable physical and chemical properties. Forest and grassland vegetation contribute to enrichment of the soil with organic residues, while tillage and mineralization of organic matter on arable land led to a decrease in humus content. Data analysis suggested that the study area did not suffer from contamination. Furthermore, it was found that the organic matter of the studied chernozems was able to bind the studied metals and retain them in an unavailable state. This phenomenon was supported by rather high correlations between humus and total heavy metal content (r = 0.946 for Pb and r = 0.975 for Cd at p &lt; 0.00001). It should be emphasized that shelterbelt forests could act as a biogeochemical barrier to the lateral migration of heavy metals. Cadmium is a rather mobile element potentially capable to migrate to adjacent environments. Therefore, regular monitoring of the agro-ecological condition of the Chernozems of the Kamennaya Steppe is required.

Evaluation of selective clay minerals and biochar as materials for sewage sludge stabilization

The objectives of this study were to evaluate sewage sludge’s stabilization with untested until now materials, such as selective clay minerals or biochar in comparison with liming, for enhancing sludge’s fertilization capacity. Dewatered sewage sludge was mixed with bentonite, vermiculite, zeolite, biochar or lime at rates of 0, 15 and 30%, air-dried and analyzed for pathogens and chemical properties. Almost all fecal indicators of treated sludge with 15% bentonite, vermiculite or biochar were reduced by at least one-logarithmic unit (log10) (indicative value of sludge’s stabilization), whereas those of limed sludge were undetectable. Electrical conductivity of all treatments significantly increased, and the highest values were obtained for untreated (6.1 dS m−1) and limed sludge (above 7.0 dS m−1 for both addition rates). The untreated sludge had the significantly highest water-soluble ammonium-nitrogen (2817 mg kg−1) and phosphorus (263 mg kg−1) concentrations followed by sludge treated with bentonite, vermiculite or biochar, whereas limed sludge had the lowest content. Boron concentration of the untreated sludge was similar to the treated sludge. Total concentrations of heavy metals were far below the legislative permissible levels for sludge’s agronomic use. Nutrients’ total content of treated sludge ranged at levels of similar magnitude to the untreated sludge, except for certain cases where they were increased because of the materials’ composition. Consequently, sewage sludge treated with 15% bentonite, vermiculite or biochar seems to be stabilized, retain bioavailable nitrogen and serve as a fertilizer of macro- and micronutrients. However, potential risks of agronomic use, i.e., soil salinization and boron phytotoxicity, should be considered.

Investigation of the Dispersed-Phase Distribution of Organochlorine Pesticides, Polychlorinated Biphenyls and Polycyclic Aromatic Hydrocarbons in Natural Water Systems

The article analyzes the patterns of the dispersed-phase distribution of organic ecotoxicants, namely organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs), in natural water systems. The relationship between the dispersed-phase distribution of individual OCPs, PCBs, and PAHs and the logarithm of the octanol-water partition coefficient log Ko/w (hydrophobicity coefficient) was established. It was shown that the water-soluble part of individual organic ecotoxicants decreases with an increase in their hydrophobicity coefficient. Eight of the given eleven correlations are clear, significant and reliable. The influence of the characteristics of the water system on the dispersed-phase distribution of organic ecotoxicants was also investigated. It was shown that the total water-soluble part of OCPs, PCBs, and PAHs decreases with an increase in the chemical oxygen demand (COD), biological oxygen demand (BOD), and the total concentration of heavy metals (Cr, Ni, Cu, Mn, Zn, Cd, Pb). Four of the nine relevant correlations are clear, significant, and reliable.