High Concentrations Of Heavy Metals Research Articles

Adsorption Performance and Mechanism of Fe(II) Adsorption in Abandoned Mine Water of Nonstick Coal

Aiming at the problem of the low reuse rate of mine water due to the high content of heavy metals in mine water, in this research, the microcharacterization means of EDX, XRD, BET, SEM, and FT-IR were used to characterize the nonstick coal in a mine in western China. The effects of solid–liquid ratio, solution pH, solution temperature, adsorption time, and initial concentration of the solution on the adsorption of Fe(II) by the nonstick coal were analyzed. The adsorption performance of nonstick coal on adsorbed Fe(II) was analyzed under different influencing factors. The results showed that the adsorption capacity and unit removal rate of the coal samples gradually decreased with the increase in the solid–liquid ratio; the adsorption amount increased with the increase in pH in an “S” shape, and the adsorption effect was better in the range of pH = 5~7; and the adsorption amount increased linearly with the temperature. The quasi-secondary kinetic model and Langmuir model could fit the adsorption kinetic curve and isothermal adsorption curve better, which indicated that the adsorption of Fe(II) by the nonstick coal was dominated by the chemical adsorption of the monomolecular layer. The quantitative analysis of the FT-IR results showed that the adsorption of Fe(II) was mainly by complexation with -OH detached from the coal samples to produce precipitation.

Contaminated Water Effects on Human Health: A Case of Pakistan

It is vital to have clean water for a healthy lifestyle. Drinking polluted and dirty water causes millions of people to perish. This study's goal was to investigate the effects of tainted water on Rahim Yar Khan's population's health. Rahim Yar Khan's water management and monitoring are subpar, and the city's subsurface water is unfit for drinking because high concentrations of calcium, magnesium, chloride, hardness, and heavy metal are present. The data's empirical component was gathered from hundred replyers in Rahim Yar Khan. The interview schedule was the tool utilized in this study's with the help of purposive sampling for data collection. Descriptive and inferential statistical methods were applied to the data analysis. This study examined public perceptions of the negative health effects after consuming contaminated water and the results shows that high level of diseases are increasing in that selected area just because of drinking contaminated water, some people seemed concerned because of poor hygiene measures for drinking water. The results of this study shows high level of health risk in that selected area for human health.

Assessment of the health risk of some heavy metals in cabbage grown on dumpsite at Hanwa in Zaria, Kaduna State, Nigeria

Pollution of soil with heavy metals can lead to high concentration of the metals in plants, consequently in animals and human body. Cadmium, Copper and Lead concentrations were determined in soil samples and cabbage (Brassica oleracea) grown on a dumpsite at Hanwa in Zaria, Nigeria. Both the soil and plant samples were digested using a mixture of Nitric acid and Perchloric acid (ratio 3:1). The metals concentrations in the samples were determined using Atomic Absorption Spectroscopy (AAS). Soil parameters like Particle Size, pH, Moisture Content, and Organic Matter were also evaluated using standard methods. The results indicated much higher concentrations of heavy metals in the soil than roots, stems and leaves of the analyzed cabbage sample. The Cd level in the plant samples ranged from 1.20 to 1.70mg/kg (site) and 0.80 to 1.00mg/kg (control). Concentration of Cu in the samples ranged from 15.50 to 35.90mg/kg (site) and 7.30 to 13.90mg/kg (control) and Pb: 19.40 to 42.70mg/kg (site) and 5.80 to 26.40mg/kg (control)were above the recommended limit by joint FAO/WHO. The Transfer Factor (TF) of the studied metals from soil to cabbage leaves were in the order of Cd (0.92) > Pb (0.58) > Cu (0.44).In this study, the Health Risk Index (HRI) for Pb (3.421) was found to be greater than 1, which indicates significant potential health risks. The high level of these heavy metals places the consumers of cabbages grown within the dumpsite area at health risk. Cultivation of vegetables on metal dumpsites should be discouraged as the soils are polluted with heavy metals.

Intercropping of Pteris vittata and maize on multimetal contaminated soil can achieve remediation and safe agricultural production

Soil contamination by multimetals is widespread. Hyperaccumulator–crop intercropping has been confirmed to be an effective method for arsenic (As)- or cadmium (Cd)-contaminated soil that can achieve soil cleanup and agricultural production. However, the influencing factors and response of hyperaccumulator–crop intercropping to multimetal-contaminated soil are still unclear. In this study, intercropping of the As hyperaccumulator Pteris vittata and maize was conducted on two typical types of multimetal-contaminated soil, namely, Soil A contaminated by As, Cd, and lead (Pb) and Soil B contaminated by As, Cd, and chromium (Cr). Intercropping reduced As, Cd, and Pb in the maize grains by 60 %, 66.7 %, and 20.4 %, respectively. The concentrations of As, Cd, Pb, and Cr in P. vittata increased by 314 %, 300 %, 447.3 %, and 232.6 %, respectively, relative to their concentrations in the monoculture plants. Two soils with different levels of contamination showed that higher heavy metal content might diminish the ability of intercropping to reduce soil heavy metal risk. No notable difference in soil microbial diversity was found between the intercropped and monocultured plants. The composition of microbial communities of intercropping groups were more similar to those of monoculture P. vittata on two different soils (Soils A and B). An imbalance between the amount of As taken up by the plants and the reduction in As in the soil was observed, and this imbalance may be related to watering, As leaching, and heterogeneity of soil As distribution. Reducing the risk resulting from As leaching and enhancing the efficiency of phytoextraction should be emphasized in remediation practices.

Modulatory Role of Biochar Properties and Environmental Risk of Heavy Metals by Co-Pyrolysis of Fenton Sludge and Biochemical Sludge.

Recent studies have reported that Fenton sludge and biochemical sludge contain high concentrations of toxic substances and heavy metals (HMs), whereas improper treatment can pose serious threats to environmental safety. Pyrolysis is considered an efficient technology to replace conventional sludge treatment. This study investigated the pyrolysis and kinetic processes of Fenton sludge and biochemical sludge, revealed the physicochemical properties of sludge biochar, and highlighted the role of co-pyrolysis in sludge immobilization of HMs and environmental risks. Results showed that Fenton sludge and biochemical sludge underwent three stages of weight loss during individual pyrolysis and co-pyrolysis, especially co-pyrolysis, which increased the rate of sludge pyrolysis and reduced the decomposition temperature. The kinetic reaction indicated that the activation energies of Fenton sludge, biochemical sludge, and mixed sludge were 11.59 kJ/mol, 8.50 kJ/mol, and 7.11 kJ/mol, respectively. Notably, co-pyrolysis reduced the activation energy of reactions and changed the specific surface area and functional group properties of the biochar produced from sludge. Meanwhile, co-pyrolysis effectively immobilized Cu, Pb, and Zn, increased the proportion of metals in oxidizable and residual states, and mitigated the environmental risks of HMs in sludge. This study provided new insights into the co-pyrolysis properties of sludge biochar and the risk assessment of HMs.

Dynamic adaptation of the extremophilic red microalga Cyanidioschyzon merolae to high nickel stress

The order of Cyanidiales comprises seven acido-thermophilic red microalgal species thriving in hot springs of volcanic origin characterized by extremely low pH, moderately high temperatures and the presence of high concentrations of sulphites and heavy metals that are prohibitive for most other organisms. Little is known about the physiological processes underlying the long-term adaptation of these extremophiles to such hostile environments. Here, we investigated the long-term adaptive responses of a red microalga Cyanidioschyzon merolae, a representative of Cyanidiales, to extremely high nickel concentrations. By the comprehensive physiological, microscopic and elemental analyses we dissected the key physiological processes underlying the long-term adaptation of this model extremophile to high Ni exposure. These include: (i) prevention of significant Ni accumulation inside the cells; (ii) activation of the photoprotective response of non-photochemical quenching; (iii) significant changes of the chloroplast ultrastructure associated with the formation of prolamellar bodies and plastoglobuli together with loosening of the thylakoid membranes; (iv) activation of ROS amelioration machinery; and (v) maintaining the efficient respiratory chain functionality. The dynamically regulated processes identified in this study are discussed in the context of the mechanisms driving the remarkable adaptability of C. merolae to extremely high Ni levels exceeding by several orders of magnitude those found in the natural environment of the microalga. The processes identified in this study provide a solid basis for the future investigation of the specific molecular components and pathways involved in the adaptation of Cyanidiales to the extremely high Ni concentrations.

Draft genome analysis for Enterobacter kobei, a promising lead bioremediation bacterium.

Lead pollution of the environment poses a major global threat to the ecosystem. Bacterial bioremediation offers a promising alternative to traditional methods for removing these pollutants, that are often hindered by various limitations. Our research focused on isolating lead-resistant bacteria from industrial wastewater generated by heavily lead-containing industries. Eight lead-resistant strains were successfully isolated, and subsequently identified through molecular analysis. Among these, Enterobacter kobei FACU6 emerged as a particularly promising candidate, demonstrating an efficient lead removal rate of 83.4% and a remarkable lead absorption capacity of 571.9mg/g dry weight. Furthermore, E. kobei FACU6 displayed a remarkable a maximum tolerance concentration (MTC) for lead reaching 3,000mg/L. To further investigate the morphological changes in E. kobei FACU6 in response to lead exposure, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed. These analyses revealed significant lead adsorption and intracellular accumulation in treated bacteria in contrast to the control bacterium. Whole-genome sequencing was performed to gain deeper insights into E. kobei's lead resistance mechanisms. Structural annotation revealed a genome size of 4,856,454bp, with a G + C content of 55.06%. The genome encodes 4,655 coding sequences (CDS), 75 tRNA genes, and 4 rRNA genes. Notably, genes associated with heavy metal resistance and their corresponding regulatory elements were identified within the genome. Furthermore, the expression levels of four specific heavy metal resistance genes were evaluated. Our findings revealed a statistically significant upregulation in gene expression under specific environmental conditions, including pH 7, temperature of 30°C, and high concentrations of heavy metals. The outstanding potential of E. kobei FACU6 as a source of diverse genes related to heavy metal resistance and plant growth promotion makes it a valuable candidate for developing safe and effective strategies for heavy metal disposal.

Egg Quality and Heavy Metal Concentrations in Meat, Eggs and Inner Organs of Laying Ducks Fed under a Conventional Feeding in Lombok, Indonesia

The search for alternative protein sources for duck feed is important considering its high cost. An experiment involving 100 forty-wk-old laying ducks was conducted for eight weeks to study the effects of fresh water fish (sapu-sapu fish -SSF) as single protein sources on egg quality and heavy metal concentration. The SSF levels were 28 and 35% of the feed and the remaining constituent was rice bran with metabolizable energy approximately 2,943 and 2,934 kcal/kg, respectively. Fresh water fish did not effect on egg quality measured except egg weight and shell thickness (63.2±0.30 to 67.9±0.22g) and shell thickness (0.50±0.04 to 0.52±0.04g) with increasing dietary SFF(P<0.05). Mean concentrations of heavy metals in local duck samples decreased in the order kidney>liver>egg>meat for Pb and liver>kidney>meat>egg for Cu. Lead concentrations in meat, eggs, liver and kidney were 1.267± 0.825, 1.311±0.737, 1.762±0.729 and 2.172±0.770 mg/kg respectively. These values were higher than the admissible amounts under the Indonesian National Standards (1.0 mg Pb/kg) and FAO (0.1 mg Pb/kg). Accumulation of Cu in the meat, eggs, liver and kidney was 12.798±4.181, 7.011±1.949, 30.165±16.561 and 14.392± 4.208 mg/kg respectively. These levels were also higher than that recommended by the European Commission. The conclusion of this study proved that feeding SSF to laying ducks raised by small farmers contained a significantly high concentration of heavy metals not appropriate for human consumption when high levels of SSF was fed

Euglena mutabilis exists in a FAB consortium with microbes that enhance cadmium tolerance

BackgroundSynthetic algal–fungal and algal–bacterial cultures have been investigated as a means to enhance the technological applications of the algae. This inclusion of other microbes has enhanced growth and improved stress tolerance of the algal culture. The goal of the current study was to investigate natural microbial consortia to gain an understanding of the occurrence and benefits of these associations in nature. The photosynthetic protist Euglena mutabilis is often found in association with other microbes in acidic environments with high heavy metal (HM) concentrations. This may suggest that microbial interactions are essential for the protist’s ability to tolerate these extreme environments. Our study assessed the Cd tolerance of a natural fungal–algal–bacterial (FAB) association whereby the algae is E. mutabilis.ResultsThis study provides the first assessment of antibiotic and antimycotic agents on an E. mutabilis culture. The results indicate that antibiotic and antimycotic applications significantly decreased the viability of E. mutabilis cells when they were also exposed to Cd. Similar antibiotic treatments of E. gracilis cultures had variable or non-significant impacts on Cd tolerance. E. gracilis also recovered better after pre-treatment with antibiotics and Cd than did E. mutabilis. The recoveries were assessed by heterotrophic growth without antibiotics or Cd. In contrast, both Euglena species displayed increased chlorophyll production upon Cd exposure. PacBio full-length amplicon sequencing and targeted Sanger sequencing identified the microbial species present in the E. mutabilis culture to be the fungus Talaromyces sp. and the bacterium Acidiphilium acidophilum.ConclusionThis study uncovers a possible fungal, algal, and bacterial relationship, what we refer to as a FAB consortium. The members of this consortium interact to enhance the response to Cd exposure. This results in a E. mutabilis culture that has a higher tolerance to Cd than the axenic E. gracilis. The description of this interaction provides a basis for explore the benefits of natural interactions. This will provide knowledge and direction for use when creating or maintaining FAB interactions for biotechnological purposes, including bioremediation.

Pre-demolition audit as a tool for appropriate CDW management – a case study of a public building

The identification of hazardous construction and demolition waste (CDW) is crucial for the appropriate and safe waste management. The pre-demolition audit is not compulsory in all EU member states, so if the control is not strict the hazardous CDW might pollute the inert fraction and create risks for human health and environment. In Bulgaria, only some industrial sites are considered as a potential source of hazardous CDW. Classification of hazards can be difficult also because the European Waste Catalogue is not specific on the hazardous CDW (with some exceptions). For example, heavy metals are among the most dangerous substances but very often remain undiscovered or underestimated. A case study of an abandoned 100-year-old public building has been performed to illustrate the importance of the pre-demolition audit. A handheld XRF analyser is used to identify contaminated materials. Samples were taken from those materials for doing leaching tests. It was proven that there was a high content of heavy metals in different paints, on internal and external walls, and fenestration. In addition to the discussion of results, some measures to separate the hazardous coatings from the recyclable masonry and wooden waste are discussed to provide higher recovery rates for the CDW.

Heavy Metal Resistant Bacteria in Rhizospheric Soil: A Review

Concern over heavy metal contamination is a common issue related to soil health. Soil is an excellent habitat for various microbes. Microbial activities in soil are negatively impacted by high concentrations of heavy metals. The physico-chemical changes of soil microorganisms are recognized as a sensitive indicator to assess soil quality. Some plants can absorb metals, and eventually, through food chains, humans and other animals are exposed to them. As a result of ongoing exposure to heavy metals, the rhizospheric bacteria of metal accumulator plants develop intrinsic or extrinsic resistance mechanisms. Through their critical contribution to metal detoxification, these resistance mechanisms either directly or indirectly support plant growth and development. Therefore, it is crucial to look into the correct mechanisms of plantrhizospheric microbe interaction in metal-contaminated soils. The current review sought to highlight the metal-resistant bacterial communities in rhizospheric soils and their part in plant health management.

Micro-essential and toxic heavy metals in surface water of Harike wetland - India

Wetlands are consequential habitats with diverse flora and fauna. The overutilization of these habitats led to the implementation of conservational strategies which includes Ramsar convention. Harike wetland is the largest wetland in northern India, declared as a Ramsar site. However, the recent industrialization and anthropogenic activities may result in the ecological degradation of this wetland. The wetland is eminently polluted due to industrial discharges, therefore the present study was undertaken to investigate heavy metal status of Harike wetland. The analysis included bio-essential (chromium, manganese, iron, cobalt, nickel, copper, zinc) and non-essential (arsenic, mercury, cadmium, lead) heavy metals. The concentration of heavy metals in the surface water was determined using inductively Coupled Plasma-Mass Spectrometry and the recovered values were compared to the global and national standards. Among all the heavy metals analysed the mean concentrations of iron (437.983 µg/l), mercury (4.011 µg/l) and lead (156.719 µg/l) were recorded to be alarming. The higher concentration of heavy metals may be directly related to the inlet from river Sutlej, as the water is contaminated by various industrial, domestic and agricultural sources. Therefore, continuous monitoring and adequate measures need to be implemented to improve the water quality of internationally recognized wetland.

Assessment of heavy metal contamination of soils in the Republic of Tatarstan using complex pollution indices NPI, RI, BGI

In this study, in most cases in soils susceptible to the accumulation of heavy metals, the highest content of heavy metals was observed in the surface layers of the soil profile. We calculated the values of three pollution indices based on the determination of individual heavy metals (Al, As, Cd, Pb, Sr) and pollutants (Cu, Co, Cr, Zn, Mn, Fe, Mo, Ni) in the territory of the Republic of Tatarstan. The overall degree of pollution and environmental risk assessment were carried out using complex indices NPI and RI. The possibility of accumulation of individual elements in soil horizons was determined using the iogeochemical index BGI. The content of heavy metals in the soils of the Republic of Tatarstan, such as As, Pb, Co, Cu, Fe in the soil horizons was several times higher than the natural content of these metals, which is confirmed by three calculated indicators, taking into account that the values obtained for the O horizon using NPI indices and RI are consistent with each other, and BGI is consistent for individual elements (As, Pb, Co, Cu, Fe, Cd, Cr, Mn and Mo).

Assessment of Some Selected Heavy Metals Concentration in the Organs of Two Different Fish Species (Clarias gariepinus and Mormyrus rume) of River Gidin Dorowa

This study was aimed to assess selected heavy metals concentration in the organs of Clarias gariepinus and Mormyrus rume from River Gidin Dorowa, Wukari, Taraba State, Nigeria. The liver, muscles and Gills of the fish species and water were collected. During dry (September, October and November,) and wet (December, January and February) seasons. Cadmium, Lead, Zinc and Copper were analyzed using Atomic Absorption Spectrometer. Sampling of fish was carried out monthly for six (6) months. The results showed that heavy metals mean were high in the muscles followed by the liver and low in the gills of Clarias gariepinus, while heavy metals were highest in the gills followed by the liver and lowest in the muscles of Mormyrus rume. High heavy metals concentration (1.900mg/kg) was recorded for Zinc (Zn) in the gills follow by copper (Cu) with a mean of (0.00917mg/kg) recorded in the liver of Mormyrus rume, Pb recorded the high mean of (0.2932mg/kg) in the liver while low lead (Pb) mean (0.1855mg/kg) was recorded in the muscle. However, Zn (1.6250mg.kg) and Pb (0.2882mg/kg) was high in the muscle than in other tissues of C. gariepinus. In other to avoid serious health hazards, there is need to institute effective fisheries pollution control measures and management of River Gidin Dorowa fisheries resources. Continuous monitoring of the pollution levels of the River Gidin Dorowa using fish species as bioindicators can provide adequate information necessary for its effective management.

Biochemical and Fe-resistant characteristics of indigene bacteria from a high iron concentration landfill in Indonesia

Bacteria isolated from leachate with high heavy metal concentration mostly have potential for bioremediation. The aim of this study was to isolate bacteria from leachate of a landfill containing high concentration of Fe. The leachate sample was collected from Gampong Jawa Landfill, Aceh, Indonesia and used to isolate the bacteria by spread method. The purification of the isolates was carried out through four quadrant plate method. Pure isolates were characterized based on the microscopic or macroscopic appearance and biochemical tests. Fe-resistance was tested by disc diffusion method and constructing the growth curve based on the optical density of broth culture media. A total of 27 pure isolates were obtained and identified, representing eight different genera: Pseudomonas, Bacillus, Neisseria, Micrococcus, Staphylococcus, Proteus, Acinetobacter, and Escherichia. Of eight isolates (each genus was represented by a single isolate), Pseudomonas sp. and Bacillus sp. were considered resistant to Fe exposure (15 ppm) with inhibition zones of 1.00 and 0.81 mm, respectively. At Fe concentration of 20 ppm the inhibition zones exceeded 1 mm, but Bacillus sp. had smaller inhibition zone than that of Pseudomonas sp. (1.15 mm versus 2.86 mm). Growth inhibition of Bacillus sp. was concentration-dependent on Fe exposure but could survive at Fe exposure up to 20 ppm. In conclusion, Bacillus sp. had a resistance against Fe exposure and its bioremediation potential is subjected for future studies.

Determination of Some Heavy Metals in Tissues of Binni Mesopotamichthys sharpeyi and Water in Al-Dalmaj Marsh/Iraq

The study was conducted in Al-Dalmaj marsh, considered one of the most important wetlands at the national and regional level and represents the most critical environment to form a good stock of Binni Mesopotamichthys sharpeyi in Iraq. The study assessed heavy metals in water and M. sharpeyi by detecting accumulation of (Nickel, Cadmium and Lead) in the tissues of gills, liver, and small intestines during the summer and winter seasons 2022-2023. The study results showed a high concentration of heavy metals in the water during summer compared to winter. Nickel levels ranged (0.19 ±0.627, 0.20 ±0.531) in water for both stations. The highest concentration was (1.339 mg/L) in suspended phase during summer, and ND in dissolved phase in winter, while Cadmium rates were (0.25±0.948, 0.17±0.478) in both stations respectively, the highest concentration was (1.827 mg/L) in suspended phase of station 1 during summer. Both stations ' lead rates were (0.39±1.455, 0.09±1.117). (3.176 mg/L) was the highest concentration in the suspended phase of station 1 during summer, while (0.121 mg/L) was the lowest in the suspended phase in winter. The results showed a sequence of concentrations of heavy metals in M. sharpeyi organs: Gills > Liver ≥ Small Intestines. The highest concentration rate of Nickel (4.109 & 3.692 mg/g) was recorded in small intestines and liver, respectively, during winter, the lowest rate (3.057 mg/g) was recorded in the gills during summer, the total of sedimentation rate of Ni in the liver and intestines was (3.726 mg/g), whereas (3.114 mg/g) in gills. Cadmium recorded an equal value of (0.957 mg/g) representing the highest percentage in the small intestines for both seasons. The highest concentrations (0.906 mg/g) in liver during summer. The total sedimentation rate of Cd in liver and small intestines was (0.852 mg/g), while (0.738 mg/g) was in gills. Lead recorded a high significant rate reaching to (8.501 mg/g) in gills during summer, followed by (6.115 mg/g) and (5.891 mg/g) in the liver and small intestines, respectively. Generally, lead reached the highest value for all elements assessed in fish at (8.501 mg/g) in the gills during summer, while (5.027 mg/g) was the highest rate in the liver during winter, and (3.709 mg/g) was the lowest rate in small intestines during winter. The total sedimentation rate of Pb in liver and small intestines was (5.185 mg/g), and (6.41 mg/g) was in the gills. Cadmium was recorded above the permissible (0.05 mg/g) limit by FAO [25] in the small intestine and liver, whereas lead exceeded the allowable limits (5 mg/g) by FAO/WHO [26]. Accordingly, the intake of these organs is unsafe for humans, and the registration of these high values poses a risk to the survival of this species as it can cause the death of fish in their environment under certain conditions.

Влияние кислых сульфатных вод на загрязнение почв террикона в Карабашском рудном районе

Introduction. Technogenic mineral formations are one of the potential sources of pollutants, including heavy metals. On the territory of the Karabash ore district as a result of copper and cobalt ore mining, waste rock heaps are formed and stored. As a result, under the influence of acidic precipitation, oxidation of the surface part of the spoil heap occurs, and the formed products, among which there are heavy metals, are transported by water and aeolian streams to the adjacent landscapes. Methods and materials of research. In the course of work investigated the spoil heap formed by wastes of the mine «Tsentralnaya» in Karabash, Chelyabinsk region. Sampling from the surface of the spoil heap, as well as soil samples with distance from it. The mineralogical composition was determined in the rocks of the heap by X-ray diffraction with Cu-Kα-radiation and crystal mono chromator. Quantitative content of heavy metals was carried out by X-ray spectral method. The reaction of the medium and carbon content of organic matter, as well as the gross content of mobile and water-soluble forms of heavy metals were determined by inversion voltammetry method. According to the results of quantitative analysis of heavy metals in soils, the coefficient of total pollution - Zc was calculated. Research results and discussion. As a result of laboratory analyses, the lithological composition of the main rocks of the spoil heap was determined, which is represented by the main two types: 1) altered quartz-chlorite-sericite schist; 2) highly transformed rocks with no discernible primary mineral composition. The first type contains mainly quartz, feldspars, mica, chlorite and pyrite. The mineralogical composition of the second group is represented by silicates and alumina silicates with gypsum, hydro-arosite and calcium sulphate. Oxidation and limonitization of spoil heap rocks is going on everywhere. In the chemical composition of spoil heaps, predominant are macro-elements Fe, Ca, Mg, K, Na, P, their concentration ranges from 0.13 to 20.38 %, also present in high concentrations of S 0.27-12.31 %, As 0.007-0.11 % and Zn 0.026-0.087 %. All other elements are less than 0.01 %. As a result of rock oxidation such heavy metals as Zn, Cd, Pb, Cu migrate from dumps in the form of sulphates, which is promoted by lowering the pH of the environment. It is revealed that soils located in the depression, on the way of hydro-genic flows, are geochemical barriers for heavy metals. The gross content of heavy metals in soils varies within high limits. Maximum concentrations were recorded in 0-10 cm layer in organogenic and grey humus horizons:Zn - 2890 mg/kg; Cd - 32 mg/kg; Pb - 1270 mg/kg; Cu - 3060 mg/kg. In the vicinity of the spoil heap, relatively high content of mobile forms of heavy metals was recorded inside the soil profile, in the surface layers of soils, with distance from the spoil heap. With distance from the heap, the share of mobile forms decreases in 2 - 2.5 times. The content of water-soluble forms of heavy metals increases with depth in the most remote soils from the spoil heap. In the course of calculations of the total coefficient of soil pollution, it follows that the soils have excessively dangerous and hazardous level of pollution. Conclusion. Thus, in the course of studies of the spoil heap of the mine «Tsentralnaya» of the Karabash ore district, the direct influence of the dumping mass on the contamination of soils of the surrounding areas by migration of heavy metals from the surface of the spoil heap by hydro-genic runoff was established. As a result, rock heterogeneities, less soluble, partially restrain the oxidation rate, forming reducing conditions. The elemental composition of the rocks showed a high content of heavy metals, making this waste rock a source of heavy metals to the surrounding environment. Resume. The instability and heterogeneity of the ongoing geochemical processes in the waste rock mass of the slag heap has been revealed, which leads to leaching of the rock mass slowly over time. Spreading of products of destruction of mineral mass of the spoil heap can be traced in soils up to 800 metres away. As a result of hydro-genic flows from the spoil heap, the soils, have a dangerous and extremely dangerous degree of contamination. As suggestions for practical application and direction of future research, the importance of this work can be noted, which can serve as a foundation for the study of such technogenic mineral formations with a view to their secondary utilization, as well as for determining the most appropriate methods of remediation of contaminated soils.

Using structural equation modeling to assess the genotoxic and mutagenic effects of heavy metal contamination in the freshwater ecosystems: A study involving Oreochromis niloticus in an urban river

Chemical pollutants represent a leading problem for aquatic ecosystems, as they can induce genetic, biochemical, and physiological changes in the species of these ecosystems, thus compromising their adaptability and survival. The Capibaribe River runs through the state of Pernambuco, located in Northeastern Brazil, and passes through areas of agricultural cultivation, densely populated cities, and industrial centers, primarily textiles. Despite its importance, few ecotoxicological studies have been conducted on its environment, and knowledge about pollution patterns and their effects on its biota is still being determined. The objective of this study was to evaluate the water quality and the damage supposed to be caused by pollutants on the DNA specimens of Nile tilapia (Oreochromis niloticus) obtained from seven strategic points of Capibaribe. Tilapia specimens and water were collected during the rainy and dry seasons from 2015 to 2017. The following characteristics were analyzed: physicochemical (six), metal concentration (seven), local pluviosity, micronuclei, and comet assay. The physicochemical and heavy metal analyses were exploratory, whereas the ecotoxicological analyses were hypothetical. To verify this hypothesis, we compared the groups of fish collected to the results of the micronuclei test and comet assay. We created a Structural Equation Model (SEM) to determine how each metal's micronuclei variables, damage index, pluviosity, and concentration were related. Our results demonstrated that the highest values for markers of genetic damage were detected at points with the highest heavy metal concentrations, especially iron, zinc, manganese, chromium, and cadmium. The SEM demonstrated that metals could explain the findings of the genotoxicity markers. Moreover, other pollutants, such as pesticides, should be considered, mainly where the river passes through rural areas. The results presented here demonstrate that the Capibaribe River has different degrees of contamination and confirm our hypothesis.

Immobilized algae for heavy metals remediation in textile wastewater

Textile wastewater has characteristics of concentrated color and containing high concentration of COD, BOD, N, P, and heavy metals. Some wastewater treatments have been developed for removal waste contaminant, especially heavy metal such as precipitation, evaporation, electroplating, ion exchange, and membrane process. These methods have disadvantages such as unpredictable of heavy metal, high reagent requirement, and generation of toxic sludge. Biosorption using immobilized algae give the alternative method to removal heavy metal in textile wastewater because of increased stability in the matrix. The main purpose of this research was to determine the adsorption of textile wastewater heavy metal using immobilized microalgae. The best ratio bead: wastewater (v/v) for removal heavy metal by immobilized microalgae of textile wastewater heavy metal in batch system was 1:3. Heavy metal Cu decreased as much as 89% with the highest final concentration of 0.2 ppm. Ability of Chlorella vulgaris and Spirulina platensis to reduce heavy metals Cr was 89% and 90% with a final concentration of 1.6 ppm and 1.5 ppm. Uptake heavy metal Cu and Cr of textile wastewater by Chlorella vulgaris reach 1.9 mg/g and 16.3 mg/g. Meanwhile for Spirulina platensis reach 1.7 mg/g and 14.7 mg/g. Based on the Langmuir equation, biosorption by Chlorella vulgaris have qmax and Kb value of heavy metal Cu was 1,984 mg/g and 0,014 mg/L. On heavy metal Cr, qmax and Kb value were 15.873 mg/g and 0.079 mg/L. Spirulina platensis have qmax and Kb value of heavy metal Cu were 1,798 mg/g and 0,014 mg/L. On heavy metal Cr qmax and Kb value were 14.925 mg/g and 0.0445 mg/L.

Nitrogen-cycling processes under long-term compound heavy metal(loids) pressure around a gold mine: Stimulation of nitrite reduction

Mining and tailings deposition can cause serious heavy metal(loids) pollution to the surrounding soil environment. Soil microorganisms adapt their metabolism to such conditions, driving alterations in soil function. This study aims to elucidate the response patterns of nitrogen-cycling microorganisms under long-term heavy metal(loids) exposure. The results showed that the diversity and abundance of nitrogen-cycling microorganisms showed negative feedback to heavy metal(loids) concentrations. Denitrifying microorganisms were shown to be the dominant microorganisms with over 60% of relative abundance and a complex community structure including 27 phyla. Further, the key bacterial species in the denitrification process were calculated using a random forest model, where the top three key species (Pseudomonas stutzei, Sphingobium japonicum and Leifsonia rubra) were found to play a prominent role in nitrite reduction. Functional gene analysis and qPCR revealed that nirK, which is involved in nitrite reduction, significantly accumulated in the most metal-rich soil with the increase of absolute abundance of 63.86%. The experimental results confirmed that the activity of nitrite reductase (Nir) encoded by nirK in the soil was increased at high concentrations of heavy metal(loids). Partial least squares-path model identified three potential modes of nitrite reduction processes being stimulated by heavy metal(loids), the most prominent of which contributed to enhanced nirK abundance and soil Nir activity through positive stimulation of key species. The results provide new insights and preliminary evidence on the stimulation of nitrite reduction processes by heavy metal(loids).