Total Nickel Content Research Articles

Development of a Neutral Mine Drainage Prediction Method Using Modified Kinetics Tests and Assessment of Sorption Capacities

Abstract Prediction of neutral mine drainage (NMD) chemistry is difficult with the predictive tools developed for acid mine drainage (AMD). To address this problem, a methodology to assess NMD risk was developed using Lac Tio Mine waste rock as a positive control. The methodology compares the maximum potential for contaminant release (in this case, nickel) using the waste rock’s total metal content and the sorption capacity of the material (qmax) combined with a mineralogical assessment and modified kinetic leaching experiments that use a chelating agent to prevent immobilization processes from occurring. The results indicate that the potential NMD risk associated with Lac Tio waste rock would be assessed as probable with the proposed methodology. Indeed, the total nickel concentrations in the Lac Tio waste rock range from 270 to 590 mg/kg. The nickel is found in Ni-rich pyrites, which proved to effectively leach when no immobilization occurred (using ethylenediaminetetraacetic acid, or EDTA, leaching). The material’s sorption capacities were between 127 and 197 mg/kg of Ni. The sorption capacity to total Ni content ratio of the material was < 1, indicating that the material has fewer sorption sites for Ni than Ni contained within the material, thereby underscoring the potential risk of Ni leaching over time. The approach proposed in this work provides an additional tool for the assessment water quality risk associated with NMD.

Chemical Properties of Agricultural Soils after Applications of Municipal Sewage Sludge

An alternative technique for disposing and managing municipal sewage sludge is its application to soils associated with crop production. The aim of the present study was to evaluate the suitability of the existing sludge application routes in terms of the fertility of the soil and the accumulation of heavy metals. A chemical analysis was carried out on four agricultural soils located in the north-central region of Algeria, which had been subjected to an irregular application of sewage sludge for more than ten years. Results showed high levels of organic matter, nitrogen, phosphorus and potassium in the sludge samples. The amended soils are characterised by an increased content of organic matter and an improved availability of nutrients, including nitrogen, potassium and phosphorus. In addition, the pH of the soil solution is close to neutral, there is an increase in the cation exchange capacity and there is no change in the electrical conductivity. The total concentrations of cadmium, copper, nickel and zinc were found to be consistently low and below the acceptable limit values for soil. Copper accumulation in P3 soil was slightly above standard (122.4 mg.kg-1). However, amended soils showed remarkable Cu (+167%) and Ni (+84%) accumulation. Whereas the total concentration of Cd is slightly lower than in the control soil, its speciation indicates a very high bioavailability. The results show that sewage sludge application has a positive effect on the availability of essential elements and the improvement of soil properties. However, inappropriate use and/or inaccurate application rates can lead to soil contamination with potentially toxic heavy metals.

Distribution and transformation of potentially toxic elements in cracks under coal mining disturbance in farmland.

The ground cracks resulting from coal mining activities induce alterations in the physical and chemical characteristics of soil. However, limited knowledge exists regarding the impact of subsidence caused by coal mining on the distribution of potentially toxic elements (PTEs) fractions in farmland soil. In this study, we collected 19 soil profiles at varying depths from the soil surface and at horizontal distances of 0, 1, 2, and 5m from the vertical crack. Using BCR extraction fractionation, we determined the geochemical fractions and total concentrations of Chromium (Cr), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd) and lead (Pb) to investigate their ecological risk, spatial fraction distribution, and main influencing factors. Results showed that the values of Cd appearing in 68.7% of the samples were higher than 40 and less than 80, presented a moderate ecological risk. Chromium (Cr), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), and lead (Pb) were mainly bound to residual fractions (> 60%) with lower mobility and Cd was dominated by F1 (acid-soluble fractions, 50%) and F2 (reducible fractions, 29%) in surface soil (0-20cm). The geochemical fractionation revealed that the mobile fractions (F1-acid-soluble and F2-reducible) of PTEs were primarily located near the crack, influenced by available potassium. In contrast, the less mobile fractions (F3-oxidizable and F4-residual) exhibited higher concentrations at distances of 2 and 5m from the crack, except for arsenic, influenced by the presence of clay particles and available phosphorus.

Phytoremediation potential and vegetation assessment of plant species growing on multi-metals contaminated coal mining site

This study aims to evaluate the plant species potential to accumulate, concentrate and translocate the heavy metals around the coal mining contaminated site with heavy metals at Harnoi, Abbottabad. The phytosociological surveys involve the systematic study of plant communities within the particular area to show their composition, structure and distribution showed that the contaminated coal mining-associated area was poor in vegetation. Among these, 11 plant species with higher important values (IV) are collected with associated soil and analyzed for the total concentrations of Cadmium (Cd), Copper (Cu), Chromium (Cr), Lead (Pb) and Nickel (Ni) using Atomic Spectrophotometer. The phytoremediation indices (BAF, BCF, TF and TI) were used to evaluate the multi-metals hyperaccumulator and stabilizer plant species. Dodonaea viscosa was evaluated as multi-metals (Cd, Cu and Ni) stabilizer. While the Ajuga bracteosa and Sonchus espera, Sisybrium officinale and Platango ovata stabilize Cd and Cr respectively. The other plant species that can stabilize as single heavy metal are Ajuga bracteosa and Sonchus espera (Cd), Sisybrium officinale and Platango ovata (Cr) and Amaranthus spinosus (Ni) respectively. While the multi-metals accumulator plant species are Bidens pilosa (Cu, Pb and Ni), Chenopodium ambrosioides (Cd, Cu and Ni), Amaranthus spinosus (Cd, Cu and Cr), Ajuga bracteosa (Pb and Ni) and Rumex hastatus (Cd and Ni). However, the single heavy metal accumulator plant species are Sonchus espera (Pb), Conyzea Canadensis (Ni), Platango ovata and Malvastrum coromandelianum (Cu) respectively. These plants could find valuable applications in practical phytoremediation for the remediation near mining tailings at Abbottabad. Moreover, the use of local plants is a promising approach not only for in situ accumulation and stabilization of heavy metals but also for tolerance and environmental adaptations in the contaminated area.

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).

Приготування і характеризація референс-матеріалу для визначення загального вмісту та рухомих форм металічних елементів у ґрунтах

Reference material of soil for determination of total content of copper, iron, manganese, nickel, and zinc, according to ISO 11466-2001, and for the operationally defined method of determination of exchangeable forms of these elements according to series of standards DSTU 4770, with ammonium acetate as an extractant is prepared and characterized. The studied material demonstrated sufficient homogeneity to exchangeable forms of metals and for the total content of copper, nickel, and zinc. The homogeneity of the material to manganese and iron is insufficient due to the presence of these metals in non-uniformly distributed magnetic microparticles (<10 μm). An interlaboratory experiment, performed to obtain assigned values of the sample characteristics, demonstrated sufficiently good agreement between the laboratories. An uncertainty of the assigned value corresponds to 30–50% for exchangeable forms of copper and nickel and 10–13% for exchangeable forms of iron, manganese, and zinc. An expanded uncertainty of assigned values of the total content of copper, nickel, and zinc is sufficient for the application of the material for methods validation and internal quality control.

ASSESSMENT OF HEAVY METAL POLLUTION IN SOIL AT A REFUSE DUMPSITE IN UNIVERSITY OF CROSS RIVER STATE (UNICROSS), CALABAR, SOUTH-SOUTH, NIGERIA

Total concentration and pollution indices of mercury (Hg), lead (Pb), chromium (Cr), cadmium (Cd), arsenic (As), nickel (Ni), and cobalt (Co) in dumpsite soil located in University of Cross River State, Calabar were evaluated in this work. Soil samples were collected at 0 - 15cm depth from two sampling stations at the dumpsite once in the months of April, August and December, 2021 and analyzed to the closest mg/kg using Atomic Absorption Spectrophotometer (AAS). The concentrations of the heavy metals showed that Cd>Pb>Ni>Cr>As>Co. All the concentrations of the heavy metals examined when compared with those of average value of heavy metals in shale showed that all the metals were lower than their corresponding world average value except Cd. Geoaccumulation index indicated unpolluted to moderately polluted for all metals studied except Cd which indicated strong to very strongly polluted. Contamination factor for Cd indicated very high contamination. Contamination degree for site 1 and 2 indicated considerable degree of contamination and moderate degree of contamination respectively. Pollution load index values investigated were within the baseline level for all the stations. The heavy metal pollution is attributable to the waste deposited at the dumpsite located in the institution. It is recommended that the dumpsite be relocated to another location that is far away from the residential area and from drinking water sources like boreholes.

Evaluation of pollution with some heavy metals for soils and plants of agricultural Locations in Basrah province

To Evaluate the state of pollution with heavy metals (Zn, Cr, Cu, Ni, Pb), ten Locations with different chemical and physical properties were selected from the agricultural Locations of Basrah province: 1/Al-Qurna, 2/Al-Madina, 3/Al-Dair, 4/Al-Haritha, and 5/Karmat Ali (University). ), 6/ Al-Tanuma, 7/ Abu Al-Khasib, 8/ Al-Siba, 9/ Al-Faw and 10/ Al-Zubayr (Al-Burjisiya station) and a site was chosen for comparison, where soil samples were collected from agricultural Locations close to the source of pollution, while plant samples were collected from near and far from the source Pollution and the necessary analyzes were Carried out for the study. The results showed an increase in the concentration of total heavy metals in the soils of most of the study Locations, and they were polluted compared to the comparison treatment. The soils of most agricultural Locations exceeded the internationally permissible limits. The results indicated that the total average concentration of lead, Nickel, copper, chromium and zinc in the Hartha area (the fourth site) was 615.88, 165.55, 390.40, 48.45, 465.83 mg kg-1 soil sequentially, which is higher compared to the average concentration in other agricultural sites, as well as the concentrations of heavy metals increased (Pb, Ni, Cu, Cr, Zn) in plants grown in locations close from the source of pollution. The concentrations of these elements decreased in plants far from the source of pollution. It is noted that the pollution factor (CF) values of Pb and Zn in all study Locations ranged from moderate contamination to very high contamination. Keywords: PLI, pollution Factor (CF), oil installations, soil pollution, plant pollution.

Spatiotemporal variability on local-regional scale in subtidal meiofaunal assemblages along the southern coast of Korea

This study was conducted to investigate the spatiotemporal variability in subtidal meiofaunal assemblages off the southern coast of Korea at local and regional scales. Abiotic and biotic samples were collected by site (three sites at least 10 km apart) within region (three coastal regions at least 50 km apart) over 7 years (2015–2021). The density and taxon richness of meiofaunal assemblages differed significantly among sites, but not among regions or years. The meiofaunal assemblage composition differed significantly among sites, regions, and years. A distance-based multivariate multiple regression analysis revealed that the mean sediment grain size and total nitrogen, lead, nickel, chromium, and aluminum concentrations were key environmental variables determining the variation of the meiofaunal assemblages. This study can provide basic ecological data for understanding the spatiotemporal distribution of meiofauna assemblages and aid in the development of management strategies to mitigate marine pollution on the southern coast of Korea.

Zoning of some physicochemical parameters in the sediments of Meighan wetland in Iran: response to urbanization, industrial, and agricultural activities.

Meighan wetland is located at 8km far away from Arak city with a population of about 600,000 citizens in the center of Iran. Several agricultural activities and industries such as metal, chemical, and mineral, as well as industrial towns, exist around the desired wetland. This research was conducted to measure the sources of chemical contaminants entering the wetland through natural and artificial waterways, to explore the trend of changes in the contaminants, and to prepare the wetland contamination zone map followed by source detection of these contaminants. Sediment samples were taken during 2019-2020 from a depth of 0-30cm from 87 points in the input waterways. The results indicated that the mean total concentrations of cadmium, nickel, lead, zinc, copper, and aluminum in sediments were estimated as 6.7, 93.4, 14.1, 276.4, 34.3, and 22,742.7ppm, respectively. The concentrations of nitrate and phosphate in the sediments were given as 18.6 and 1.8ppm, respectively. The mean comparison indicated that the most significant level of nickel and lead belonged to the input waterways of industrial and urban regions; the maximum cadmium content was seen in the input waterways from the agricultural lands; and the highest level of zinc and aluminum was recorded in the waterways of agricultural-industrial urban regions. There was a significant relationship between the results of classic statistics and zoning found in GIS. Overall, chemical pollutants with the origin of input wastewater from the treatment plant of wastewater and the input waterways from the industrial and urban regions have had the largest share of contamination for Meighan wetland.

Preliminary study of geochemical speciation of copper and nickel in coastal sediments in Surabaya, Indonesia.

Surabaya is one of the big coastal cities in Indonesia with rapid municipal development. Thus, the investigation on the metal's geochemical speciation in the coastal sediment is required to assess the environmental quality by studying their mobility, bioavailability, and toxicity. This study is aimed at evaluating the condition of the Surabaya coast by assessing copper and nickel fractionations and total concentrations of both metals in sediments. Environmental assessments were performed by using geo-accumulation index (Igeo), contamination factor (CF), and pollution load index (PLI) for existing total heavy metal data and by using individual contamination factor (ICF) and risk assessment code (RAC) for metal fractionations. Copper speciation was observed geochemically in the fraction order of residual (9.21 - 40.08mg/kg) > reducible (2.33 - 11.98mg/kg) > oxidizable (0.75 - 22.71mg/kg) > exchangeable (0.40 - 2.06mg/kg), while the detected fraction order of nickel was residual (5.16 - 13.88mg/kg) > exchangeable (2.33 - 5.95mg/kg) > reducible (1.42 - 4.74mg/kg) > oxidizable (1.62 - 3.88mg/kg). Different fraction levels were found for nickel speciation wherein its exchangeable fraction was higher than copper, even though the residual fraction was dominant for both copper and nickel. The total metal concentrations of copper and nickel were found in the range of 13.5 - 66.1mg/kg dry weight and 12.7 - 24.7mg/kg dry weight, respectively. Despite the fact that almost all index values are detected low through total metal assessment, the port area is indicated to be in the moderate contamination category for copper. Through the assessment of metal fractionation, copper is classified into the low contamination and low-risk category, while nickel is categorized into the moderate contamination level and medium risk to the aquatic environment. Although the coast of Surabaya generally remains in the safe category for living habitat, certain sites had relatively high metal concentrations estimated to have originated from anthropogenic activities.

Applicability of Compost and Mineral Materials for Reducing the Effect of Diesel Oil on Trace Element Content in Soil.

Petroleum-derived substances have become the factor adversely affecting the soil quality and, also, crop production. However, the ability to immobilise contaminants is limited in anthropogenically altered soils. Therefore, a study was undertaken to evaluate the effects of soil contamination with diesel oil (0, 2.5, 5 and 10 cm3 kg-1) on the contents of trace elements in the soil and determine the suitability of different neutralising materials (compost, bentonite and calcium oxide) for the in situ stabilisation of soil contaminated with this petroleum derivative. In the soil contaminated with the highest dose of diesel oil (10 cm3 kg-1), a decrease in chromium, zinc and cobalt and an increase in the total nickel, iron and cadmium concentrations were found in the series without the addition of neutralising materials. Remediation with compost and mineral materials contributed to a significant reduction of nickel and iron, as well as cobalt, in soil (calcium oxide only). All materials used contributed to an increase in cadmium, chromium, manganese and copper in the soil. The above-mentioned materials (most notably calcium oxide) can be successfully used to reduce the effect of diesel oil on the contents of some trace elements in soil.

Sediment-associated heavy metal contamination and potential ecological risk along an urban river in South Africa

Sediment contamination by heavy metals poses one of the worst environmental risks to aquatic ecosystems worldwide. The study explored sediment-associated heavy metal contamination and potential ecological risk along the Molopo River in Mahikeng, South Africa. Total concentrations of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), and zinc (Zn) were analysed using inductively coupled plasma mass spectrometry. Various indices were applied to assess the level of contamination and ecological risk. Most heavy metal concentrations at selected upstream and downstream sites were below average shale, except Cr, Cu, Hg, Pb, and Zn. The contamination factor (CF) indicates that the level of contamination was low (CF < 1) at most sampling sites, except Cr, Cu, Pb and Zn, which varied from moderate (1 CF < 3) to considerable (3 ≤ CF < 6) contamination. The enrichment factor (EF) shows that Cd, Cr, Cu, and Zn were moderate (2 EF < 5) to significantly enriched (5 EF < 20) at the affected sites. The results suggest anthropogenic enrichment (EF > 2) of Cd, Cr, Cu, and Zn. The threshold effect concentration and probable effect concentration sediment quality guidelines predicted that Cr, Cu, and Ni concentrations were more likely to have harmful effects on bottom-dwelling organisms. Pearson correlation and principal component analysis reveal that Cd, Cr, Cu, Ni, Pb, and Zn had a common anthropogenic source. We attribute the source to industrial and wastewater effluent, vehicle traffic, and runoff from various urban surfaces in the city. The study provides baseline data for heavy metal monitoring in the study area. Future research and monitoring should focus on heavy metals that cause concern because of their concentrations (Cr, Cu, Pb, and Zn) and potential ecological risk (Cr, Cu, and Ni).

Role of suspended particulate material on growth and metal bioaccumulation in oysters (Crassostrea gigas) from a French coastal semi-enclosed production area, Arcachon Bay

Arcachon Bay is a prominent oyster production area on the coast of Western Europe, and is subject to chemical contamination including by trace metals. Recently, the national “mussel-watch” monitoring network – using local bivalves as semi-quantitative bioindicators of coastal chemical contamination – highlighted a significant increase in copper (Cu) concentrations in oysters from this bay. Here, we conducted a one-year multi-compartment and multi-parameter field study to investigate some aspects of the surrounding environment of oysters that could explain their metal bioaccumulation. Sediment, seawater (through punctual and passive sampling), particles (suspended particulate material of selected sizes, including trophic resources for oysters) and transplanted oysters were regularly collected at two contrasted sites of the bay (i.e. under continental versus more oceanic influence). These matrices were characterised for their total Cu, zinc (Zn), nickel (Ni), cadmium (Cd) and lead (Pb) concentrations. Several physico-chemical and biological parameters (e.g. salinity, particle loads, oyster growth rate and condition indices, carbon and nitrogen stable isotope compositions, etc.) were also analysed. Overall, sediment, particles and oysters from the outermost site had slightly lower δ 13 C values, confirming the more oceanic influence in this part of the bay. Among organic particles, although dinoflagellates tended to be more abundant at the outermost site while ciliates were more abundant at the innermost site of the bay, the two sites did not differ in mean total microphytoplankton and diatom densities. However, the variations observed for most of the other parameters studied show that oysters located near the continental shore are exposed to higher loads of particles in general, and to higher metal contents in the dissolved phase and “bulk” seawater (dissolved plus particulate phases) during the year. While fluvial inputs and continental/urban run-offs are suspected sources of anthropogenic metal inputs into the bay, (fine) sediment particle resuspension appears to be a likely major contributor to metal release and hence to the contamination of the bay including oysters. The decline of seagrass beds in the last two decades in the bay could also have decreased the potential of fine particle retention in the sedimentary stratum. Concomitantly, oysters presenting the highest metal concentrations were those with the lower growth rates and condition indices, which may be induced by physical constraints, high amounts of pseudo-faeces produced and/or reduced food and energy acquisition by oysters due to high particle loads in the water column. The findings of this study imply that using raw metal concentrations in bivalves to monitor marine coastal contamination can lead to misleading interpretations if potentially great spatial variations in bivalve growth rates or condition indices are not considered. Finally, peculiar trends were observed for Cu compared to other metals, highlighting the need of further studies to fully address the Cu contamination in this marine system (e.g. specific sources of contamination for this metal in the bay). This study more broadly raises the issue of potentially man-induced ecological changes (e.g. modification of natural habitats) and their consequences on metal transfer and physiological performance of marine biota. • A multi-compartment and multi-parameter study to unravel oyster metal contamination. • Higher contamination found in dissolved and particulate seawater phases inside the bay. • Contamination likely explained by river flows and tidal resuspension of sediments. • Higher particle loads observed with higher oyster metal concentrations and lower growth. • Differences in oyster bioaccumulation patterns for copper compared to other metals.

Exposure of the Portuguese population to metals and metalloids: results from a national study

Metals and metalloids are elements present in the environment that can originate from natural and anthropogenic sources. However, exposure to some of these elements can cause adverse health effects due to their toxicological potential. As such, it is important to assess their levels in the human body, which can be done through human biomonitoring. Several studies assessed these elements’ levels in the Portuguese population, but were mainly focused on hotspots or specific groups. As such, the aim of this work was to assess the exposure to metals and metalloids in the Portuguese population using samples collected in the study &amp;#x22;Exposure of the Portuguese Population to Environmental Chemicals: a study nested in INSEF 2015&amp;#x22; (INSEF-ExpoQuim). INSEF-ExpoQuim was an epidemiologic study including 297 participants aged 28-39 years, living in Portugal for &amp;#x2265; 12 months and able to follow an interview in Portuguese. Fieldwork was developed between June 2019 and February 2020 following the guidelines of the HBM4EU project. First morning urine samples were collected along with data on sociodemographic characteristics, living conditions and residential history, habits/lifestyle, nutrition, health, occupation and substance specific information. Total concentrations of arsenic (As), lead (Pb), cobalt (Co), copper (Cu), manganese (Mn), molybdenum (Mo), nickel (Ni), selenium (Se) and zinc (Zn) were determined by inductively coupled plasma mass spectrometry. As, Cu, Mo, Se and Zn were detected in the majority of the samples analysed, while Mn was detected in around half and Pb, Co and Ni were detected in less than half. Results will be presented, including a description of the biomarkers’ levels in the Portuguese population. This study is the first developed in Portugal to provide an assessment of the exposure at a national level and its results may support the development and implementation of policy measures aimed at minimizing exposure and improving the population’s health.

Nivel de contaminación del suelo con arsénico y metales pesados en Tiquillaca (Perú)

The Andes plays an important role in the providing of ecosystem services, however, the greatest threat it faces today is soil contamination by heavy metals, which constitutes a risk in the interaction of man and the environment, in this understanding it is necessary to promote research in the mountainous region in activities that contravene the sustainable development of the region. In this sense, the objective of this study is to evaluate the level of soil contamination by heavy metals by means of the geo-accumulation index and to predict the influence of pH and organic matter on the distribution of metals in the soil. The methodology involved the extraction of four soil samples obtained in an area adjacent to the Paxa stream, where mining waste was dumped; the total concentration of Arsenic, Barium, Cadmium, Copper, Chromium, Lead, Nickel and Zinc was evaluated by the optical emission spectrophotometry method, pH and organic matter by potentiometry and colorimetry, respectively. The results showed geo-accumulation indices for As, Cd, and Pb with moderately to heavily contaminated (class 1, 2 and 3, respectively).In contrast, soils were not contaminated with Ba, Cr, Cu, Ni and Zn (class 0), which represents a risk for the Andean ecosystem, given the acidic characteristics of the soil (4.08) and minimum organic matter content (0.9%), which will promote the solubility and mobility of heavy metals in the ground.

Physicochemical properties and metal speciation in gas flare-impacted soils in Ibeno, NigeriaPhysicochemical properties and metal speciation in gas flare-impacted soils in Ibeno, NigeriaPhysicochemical properties and metal speciation in gas flare-impacted

The physicochemical properties and metal speciation in gas flare-impacted soils in Ibeno, Nigeria was assessed in this study. During the study, surface soils were collected from five (5) communities impacted by gas flaring within Ibeno namely: Ukpenekang, Mkpanak, Atabrikang, Inua-Eyet Ikot, and Okorutip. Surface soils were also collected from a location outside Ibeno where there is no impact of gas flaring and used as the Control. These samples and Control were treated analytically and analysed for their physicochemical properties and the different fractions of the metals using standard procedures. Results obtained in the studied soils indicated that, the mean values of pH, organic carbon, electrical conductivity, and cation exchange capacity were all within their acceptable limits. The mean total concentrations of lead (Pb), cadmium (Cd), and nickel (Ni) were also within their recommended limits whereas, the mean total concentration of iron (Fe) was higher than the acceptable limit. However, the levels of all the physicochemical properties including the total concentrations of the trace metals in the studied gas flare-impacted soils were much higher than their levels in the control plot. Results of metal speciation in the studied soils revealed that, Pb and Cd existed predominantly in the acid extractable fraction, Ni in the reducible fraction while, Fe existed mainly in the residual fraction. Nevertheless, in the control plot Pb and Cd existed predominantly in the reducible fraction, Ni in the residual fraction while Fe existed in the residual fraction. The Principal component analysis revealed that anthropogenic factor impacted significantly on all the parameters determined except Fe. The Hierarchical cluster analysis confirmed that, all the parameters determined except Fe emanated mainly from the anthropogenic source and also indicated strong relationships among the parameters. The study revealed that, all the metals in the studied gas flare-impacted soils were in the moderate class of contamination factor. The ecological risk factor and potential ecological index of the metals were in the low ecological risk.

Assessment of Metal Intake by Selected Food Supplements Based on Beehive Products.

The aim of this study was to determine the quantity of particular toxic metals (Pb, Cd, As, Hg) and micronutrients (Cr, Fe, Co, Ni, Cu, Zn, Se) in the recommended daily dose of 51 food supplements based on beehive products. Samples taken from the Croatian market were submitted for the identification/quantification of studied metals and micronutrients. It was carried out by means of inductively coupled plasma mass spectrometry (ICP-MS). Eleven samples (21.57%) showed an increased concentration of total arsenic, three samples (5.88%) contained an increased concentration of total iron, and eight samples (15.68%) had an increased concentration of total nickel. Three samples (5.88%) contained an increased concentration of zinc, while one sample (1.96%) contained an increased concentration of selenium. Increased levels of certain toxic metals and micronutrients do not pose a danger to human health because the amount identified was less than what can cause toxic effects in humans. All other analysed metals and micronutrients fell within the defined literature values. Despite certain increases in particular parameters, all samples met the established toxicity criteria. This study evidenced their safety if consumed in the recommended daily dose.

Moderately hazardous microelements in the soils of saline agrolandscapes of the Baraba plain

When developing adaptive-landscape farming systems, special attention is paid to the study of the ecological, toxicological and sanitary-hygienic state of the territory used. This is especially important for saline agro-landscapes, which are widespread in the Barabinskaya plain (Baraba). The studies were conducted in the northeastern part of the Baraba within the Novosibirsk Region. The soils of the eluvial (meadow-chernozem), transit (chernozem-meadow), and accumulative (deep solonetz) zones of the catena were studied. The soils differed in physicochemical properties and microelement composition. In the soil profile from the eluvial to accumulative zone, alkalinity increased, humus content decreased, and the granulometric composition changed. These indicators affect the microelement composition. The content of moderately hazardous trace elements (hazard class 2): chromium (Cr), nickel (Ni), cobalt (Co) and molybdenum (Mo) were determined. It was found that the maximum content of total chromium falls on the profile of meadow-chernozem soil in the eluvial position. In the arable horizon there is less than 0.00001 mg/kg of mobile chromium, which does not fall within the detection range of the device. Some movement of mobile forms of chromium from the eluvial to accumulative position was noted. The maximum content of total nickel and cobalt was found in the profile of meadowchernozem soil, but it is in amounts well below the LOC. The total content of nickel and cobalt varies insignificantly across the soil profile, indicating their low mobility. The total content of Mo in soils is within the clarke range and is approximately the same over the entire depth. It was found that the content of moderately hazardous trace elements of nickel and cobalt in the soils of saline agro-landscapes of Baraba by catena is below the LOC and cannot be a hazard from the ecological-toxicological point of view. The content of total chromium and molybdenum is on the verge of the LOC and therefore, in certain cases, tension in the ecological and toxicological situation of the territory may arise. This should be taken into account in the agricultural use of saline agrolandscapes.

Phosphorus Cycle and Primary Productivity Changes in the Tethys Ocean During the Permian-Triassic Transition: Starving Marine Ecosystems

The ultimate cause(s) of the end-Permian mass extinction (∼252 Ma ago) has been disputed. A complex interplay of various effects, rather than a single, universal killing mechanism, were most likely involved. Climate warming as consequence of greenhouse gas emissions by contemporaneous Siberian Traps volcanism is widely accepted as an initial trigger. Synergetic effects of global warming include increasing stratification of the oceans, inefficient water column mixing, and eventually low marine primary productivity culminating in a series of consequences for higher trophic levels. To explore this scenario in the context of the end-Permian mass extinction, we investigated sedimentary total organic carbon, phosphorus speciation as well as nickel concentrations in two low-latitude Tethyan carbonate sections spanning the Permian-Triassic transition. Total organic carbon, reactive phosphorus and nickel concentrations all decrease in the latest Permian and are low during the Early Triassic, pointing to a decline in primary productivity within the Tethyan realm. We suggest that the productivity collapse started in the upper C. yini conodont Zone, approximately 30 ka prior to the main marine extinction interval. Reduced primary productivity would have resulted in food shortage and thus may serve as explanation for pre-mass extinction perturbations among marine heterotrophic organisms.