AQUA REGIA

Natural metal background levels in sediments are critical to assess spatial and temporal trends of contamination in hydrosystems and to manage polluted sediments. This is even more sensitive that multi-factors such as geogenic basement, depositional context, and past or long-term pollution can affect the level of metals in sediments. This article provides natural metal background levels and ancillary data (location, chronology, grain-size, total organic carbon -TOC) in preindustrial sediments along the Rhône River (France). Two distinct areas were selected to take into account the geological variability of the watershed: the Dauphiné Lowlands (Upper Rhône River) and the Tricastin Floodplain (Middle Rhône River). On each area, the sediment cores were retrieved from palaeochannel sequences and the sampled sections were dated by radiocarbon from the Roman to the Modern Times (AD 3-1878). Regulatory metals (Al, Fe, Cd, Cr, Cu, Ni, Pb, and Zn) and other trace elements (Ba, Co, Li, Mg, Mn, Na, P, Sr, Ti, V) were analysed following both Aqua Regia (AR) and Total Extraction (TE) procedures. Classically, TE

Herbs are extensively consumed in the United Arab Emirates for their flavoring and medicinal properties. This study aimed at determining the concentration of heavy metals in selected traditional herbs consumed in the United Arab Emirates (UAE). A total of 81 samples of seven herbs, parsley (Petroselinum crispum), basil (Ocimum basilicum), sage (Salvia officinalis), oregano (Origanum vulgare), mint (Mentha spicata), thyme (Thymus vulgaris), and chamomile (Matricaria chamomilla), were purchased from the local market in Dubai and analyzed for their cadmium, lead, copper, iron, and zinc contents. Microwave-assisted digestion was applied for the dissolution of the samples and heavy metals concentration was determined using Atomic Absorption Spectrometry (AAS). Metals were found to be present in varied concentrations in the herb samples. The concentration ranges were found as follows: less than 0.1–1.11 mg·kg−1for cadmium, less than 1.0–23.52 mg·kg−1for lead, 1.44–156.24 mg·kg−1for copper...

Strontium isotopes ( 87 Sr/ 86 Sr) are useful in the Earth sciences as well as in forensic, archaeological, palaeontological, and ecological sciences. As very few large-scale Sr isoscapes exist in Australia, we have identified an opportunity to determine 87 Sr/ 86 Sr ratios on archive fluvial sediment samples from the low-density National Geochemical Survey of Australia (www.ga.gov.au/ngsa; last access: 15 December 2022). The present study targeted the northern parts of Western Australia, the Northern Territory and Queensland, north of 21.5 °S. The samples were taken mostly from a depth of ~60-80 cm in floodplain deposits at or near the outlet of large catchments (drainage basins). A coarse (< 2 mm) grain-size fraction was airdried, sieved, milled then digested (hydrofluoric acid + nitric acid followed by aqua regia) to release total Sr. The Sr was then separated by chromatography and the 87 Sr/ 86 Sr ratio determined by multicollector-inductively coupled plasma mass spectrometry. Preliminary results demonstrate a wide range of Sr isotopic values (0.7048 to 1.0330) over the survey area, reflecting a large diversity of source rock lithologies, geological processes and bedrock ages. Spatial distribution of 87 Sr/ 86 Sr shows coherent (multi-point anomalies and smooth gradients), large-scale (> 100 km) patterns that appear to be broadly consistent with surface geology, regolith/soil type, and/or nearby outcropping bedrock. For instance, the extensive black clay soils of the Barkly Tableland define a > 500 km-long northwest-southeast-trending unradiogenic anomaly ( 87 Sr/ 86 Sr < 0.7182). Where carbonate or mafic igneous rocks dominate, a low to moderate Sr isotope signature is observed. In proximity to the outcropping Proterozoic metamorphic basement of the Tennant, McArthur, Murphy and Mount Isa geological regions, conversely, radiogenic 87 Sr/ 86 Sr values (> 0.7655) are observed. A potential correlation between mineralisation and elevated 87 Sr/ 86 Sr values in these regions needs to be investigated in greater detail. Our results to-date indicate that incorporating soil/regolith Sr isotopes in regional, exploratory geoscience investigations can help identify basement rock types under (shallow) cover, constrain surface processes (e.g. weathering, dispersion), and, potentially, recognise components of mineral systems. Furthermore, the resulting Sr isoscape and future models derived therefrom can also be utilised in forensic, archaeological, paleontological and ecological studies that aim to investigate, e.g., past and modern animal (including humans) dietary habits and migrations. The new spatial Sr isotope dataset for the northern Australia region is publicly available (de Caritat et al.

The revised (four-step) BCR sequential extraction procedure has been applied to fractionate the chromium, copper, iron, manganese, nickel, lead and zinc contents in urban soil samples from public-access areas in five European cities. A preliminary inter-laboratory comparison was conducted and showed that data obtained by different laboratories participating in the study were sufficiently harmonious for comparisons to be made between cities and land types (e.g. parks, roadside, riverbanks etc). Analyte recoveries by sequential extraction, with respect to direct aqua regia digestion, were generally acceptable (100 ± 15%). Iron, nickel and, at most sites, chromium were found mainly in association with the residual phase of the soil matrix. Copper was present in the reducible, oxidisable and residual fractions, whilst zinc was found in all four sequential extracts. Manganese was strongly associated with reducible material as, in some cities, was lead. This is of concern because high lead concentrations were present in some soils (> 500 mg kg -1 ) and the potential exists for remobilisation under reducing conditions. As would be expected, extractable metal contents were generally highest in older, more heavily industrialised cities. Copper, lead and zinc showed marked (and often correlated) variations in concentrations between sites within the same city whereas manganese and, especially, iron, did not. No overall relationships were, however, found between analyte concentrations and land use, nor between analyte partitioning and land use.

Sediments as a tool for monitoring contamination by heavy metals in the environment has long been considered. It is therefore a necessity to produce reliable data for such purposes. Microwave-assisted acid dissolution has proved to be a suitable method for digesting complex matrices, such as sediments. However, due to the infancy of the technique, the procedures are numerous and varied in both the reagents used and microwave conditions. In this study, the efficiency of two recommended acid mixtures, a HNO3-HF mixture and an aqua regia-HF mixture, under the same microwave digestion conditions were compared using certified reference materials. It was observed that the HNO3-HF mixture showed better efficiency than the aqua regia-HF mixture in most of the heavy metals analyzed in all certified reference materials used.

Sediments as a tool for monitoring contamination by heavy metals in the environment has long been considered. It is therefore a necessity to produce reliable data for such purposes. Microwave-assisted acid dissolution has proved to be a suitable method for digesting complex matrices, such as sediments. However, due to the infancy of the technique, the procedures are numerous and varied in both the reagents used and microwave conditions. In this study, the efficiency of two recommended acid mixtures, a HNO3-HF mixture and an aqua regia-HF mixture, under the same microwave digestion conditions were compared using certified reference materials. It was observed that the HNO3-HF mixture showed better efficiency than the aqua regia-HF mixture in most of the heavy metals analyzed in all certified reference materials used.

This report presents the methods and method performance data for the determination of methylmercury concentrations in solids and suspended solids. Using the methods outlined here, the U.S. Geological Survey's Wisconsin District Mercury Laboratory can consistently detect methylmercury in solids and suspended solids at environmentally relevant concentrations. Solids can be analyzed wet or freeze dried with a minimum detection limit of 0.08 ng/g (as-processed). Suspended solids must first be isolated from aqueous matrices by filtration. The minimum detection limit for suspended solids is 0.01 ng per filter resulting in a minimum reporting limit ranging from 0.2 ng/L for a 0.05 L filtered volume to 0.01 ng/L for a 1.0 L filtered volume. Maximum concentrations for both matrices can be extended to cover nearly any amount of methylmercury by limiting sample size.

Introduction: D-004 is a lipid extract from the Cuban royal palm tree (Roystonea regia) fruits, containing a mixture of fatty acids, mainly oleic, palmitic, lauric and mirystic. This mixture has proved to prevent prostatic hyperplasia induced with testosterone and phenylephrine in rodents. Objective: to determine toxic effects of D-004 orally administered at doses up 2 000 mg/kg, to Sprague Dawley rats from both sexes. Methods: oral acute toxicity of D-004 (2 000 mg/kg) was investigated according to the Acute Toxic Class Method. In the subchronic study, rats were treated with D-004 at 500, 1 000 and 2 000 mg/kg for 90 days while in the chronic study, animals were administered with D-004 at 800, 1 500 and 2 000 mg/kg/day during twelve months. Results: no evidence of treatment-related toxicity was detected. Thus, clinical observations, control of body weight and food consumption, blood biochemical and haematological parameters, organ weight ratios and histopathological findings showed...

The effectiveness and characterization of blended composite materials made of modified biomaterials and iron (III) sulfate coagulant to remove selected dissolved heavy metals from water-chosen samples were determined during the rainy and dry seasons by inductively coupled plasma optical emission spectroscopy (ICP-OES). Water samples were mechanically batch agitated at their prevailing pHs with optimal composite doses. Following the treatment during the rainy season, the results indicated a percent elimination range of 62.16-99.19 percent. Cu > Zn > Pb > Cd; Zn > Cu > Pb > Cd; Pb > Cu > Cd > Zn; and Zn > Cu > Cd > Pb were the percent removal trends in the Funai borehole water (FBW), Assemblies of God church borehole water(ABW), Ebonyi River water (EBRW), and Eziyiaku river water, Akaeze (ERWA) samples, respectively. During the dry season, a removal range of 93.70-100 percent was recorded in all samples. Concentrations of all residual metals except Cd satisfied the World Health Organization and Nigerian Standard Organization permissible levels. Interactions of the variables at (p<0.05, p<0.01, and p<0.001) indicated a statistically significant difference. The reduced linear model of analysis of variance (ANOVA) and response surface methodology employed to predict the responses of main and interaction effects of variables for the dosage optimization of composite materials indicated suitability and statistical significance.

One of the most important man-induced land transformations since many centuries is the terraced landform, an agricultural technique that characterizes many agroecosystems all over the world. In this study, our objectives were: i) to evaluate the background level of heavy metals in soils of a terraced ecosystem in the proximity of the Dolomites natural park, in northern Italy; ii) to ascertain the metal concentration range and spatial distribution; iii) to identify possible contamination of some sites, and the related environmental hazard. Six different terraced landforms were selected; totally, 32 representative soil profiles were opened and sampled. Specific analyses of 15 potentially harmful trace elements (Sb, As, Be, Cd, Co, Cr, Hg, Ni, Pb, Cu, Se, Sn, Tl, V and Zn) were carried out in the laboratory by ICP-MS after digestion with HF and HClO4. Background levels of heavy metals in the soils investigated are consistent with currently recorded trace element concentrations of soils from Western Europe. A geological matrix effect may be accounted for metal release by parent material weathering. Nevertheless, metal accumulation in surface horizons at some sites has been recorded, and may be ascribed to atmospheric input. The extreme parts of the territory investigated, moreover, present significant concentrations of some metals. In particular, Cu, Pb and Zn contents in surface horizons suggest an anthropogenic enrichment. The human contribution could be due to past mine activities in the close vicinity, and metals have been probably vehicled southward through stream and/or wind transport. Moreover, Sn shows amounts overall above the allowed legislation threshold. In some cases it was not possible to assess if the presence, or the concentration level, of a metal could be related to natural sources or to recent, or past, human activities.

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Predicting metals concentration in agricultural soils is a sine qua non in establishing environmental policies and evaluating the soils' agricultural potentials in an area. The relevance of metals to ecological health, agriculture and pollution has sprung a lot of related studies. This study was set-up to determine the concentration and profile distribution of aqua regia (AR) extractable Fe, Al, Mn, Mg and K in agricultural soils, and to predict AR extracted elements via Al2O3 (Alx), K2O (Kx), physical and chemical properties for soil fertility interpretations. One soil pit was randomly sited in each slope transition obtained via digital elevation models (DEM), resulting in 27 composite soil samples. Soil samples meant for AR and X-ray florescence were analyzed in triplicate. The soils were dominated by AR extractable Fe with mean concentrations showing the trend; Fea> Ala> Mga> Mna≈Ka and ranges

The economically important activity of metal processing can tend to contribute to the degradation of the environment. Smelting is an important source of contaminants, dispersing large quantities of potentially toxic elements (PTE) and coproducts into the environment. Soils in the vicinity of smelters frequently contain high concentrations of PTE. In terms of the quantities processed, the major PTE are iron (Fe), aluminium (Al), copper (Cu), lead (Pb), manganese (Mn), and zinc (Zn); of these Cu, Pb and Zn are, potentially, highly hazardous elements. The general problem addressed by this study is to determine if the PTE concentration in the soils of an area downwind from a decommissioned iron smelter (46°04′16″N, 8°15′47″E) still shows signs of past contamination, and to discuss the options for intervention. The history of pollution of Villadossola soils due to the steel business comprises the last 150 years. We measured pseudo-total (aqua regia) and available (EDTA) PTE in soils over an area of 15 km 2 near to the pollution source. Here we show that four decades after the end of the polluting event, when the total emissions originating from the smelter followed the order of magnitude Zn ≫ Cr ≫ Fe ≈ Pb ≈ Ca > Mn ≫ Cu > Ni ≈ Cd, the soil feedback, presented in terms of enrichment ratios, follows the order Cd > Bi ≫ Pb > Cu > Zn > Sb ≈ As > Cr. The total concentrations of PTE in the topsoil are: 101 mg Cr, 8 mg Co, 41 mg Ni, 70 mg Cu, 143 mg Zn, 6 mg As, 1.3 mg Cd, 0.5 mg Sb, 92 mg Pb, and 1.3 mg Bi kg -1 soil, with standard errors exceeding 50%. Our results show that it is unlikely that soils in the vicinity of the former smelter are a source of disproportionate human intake of PTE, and that the cost of reclamation would reach one quarter of the total annual budget of the municipality. Options for reducing the risks rely on the optimisation of the risk assessment factors, by adopting soil conservation practices. People take sick, for example, from breathing high levels of smoke from fuels used in cooking or heating. There is also pollution that affects everyone, caused by transport, industrial fumes, substances which contribute to the acidification of soil and water, fertilisers, insecticides, fungicides, herbicides and agrotoxins in general. […] But our industrial system, at the end of its cycle of production and consumption, has not developed the capacity to absorb and reuse waste and by-products. […] In some countries, there are positive examples of environmental improvement: […] they do show that men and women are still capable of intervening positively. […] We need only recall how ecosystems interact in dispersing carbon dioxide, purifying water, controlling illnesses and epidemics, forming soil. From the Encyclical Letter Laudato Si' by Pope Francis, given in Rome at Saint Peter's on

In order to estimate plant available fraction of metals in three soils, three vegetable samples: Amaranthus viridis, Celosea argentea and Corchorus olitorius were grown on contaminated soils. Matured plants were harvested and analyzed for their metal concentration. The soil samples were collected before and after planting, acid digested and analyzed to determine the pseudo total metal concentration, and quantification was done using flame -atomic absorption spectroscopy (FAAS). To correlate metal accumulation by these plants with potential bioavailability of metals in soils, sequential extraction (SE) using the modified BCR technique was performed on the soils. A secondary soil reference material (GLAURM) was used for quality control. The results of the reference material showed that the found values were within three standard deviations of the target values for the elements determined in the aqua regia digests and for most steps of the SE. It was observed that each metal differed considerably in uptake. Of the plants investigated, A. viridis had the highest tissue concentration of Cd, Cr, Pb and Zn from the soils with concentration of 1.4, 5.2 and 3.2 mgkg -1 of Cd, 76.5, 96 and 43.0 mgkg -1 of Cr, 49.5, 20.0 and 27.4 mgkg -1 of Pb and 78.1, 112 and 96.9 mgkg -1 of Zn in the soil from sites A, B and C respectively. Results of SE showed that Cd and Zn were mostly present in the acid exchangeable and reducible fractions, where these metals were mostly taken up. Soil-to-plant transfer factor values decreased in the order Zn > Cd > Cr > Pb.

Analysis of soil around the vicinity of Arufu mine field was conducted in order to ascertain the impact of mining on the environment. Concentrations of trace metals associated with Pb – Zn – barite mineralization were determine in soils using atomic absorption spectrophotometer (AAS) Varian AA 240, after acid digestion with a mixture of 1:1 hydrofluoric acid and aqua regia. Mean concentrations (µg/g) of metals ranged from 5.72 (As) – 451.44 (Pb) in dry season and 1.32 (Cd) – 504.61 (Pb) in wet season. Index of geoaccumulation were in the following order of increasing magnitude: Cu &lt; Zn &lt; As &lt; Pb &lt; Ag for dry season and Cu &lt; As &lt; Zn &lt; Cd &lt; Pb for wet season. On the other hand, soil enrichment ratio ranged from Cu (1.06) – Ag (126.18) and Cu (1.35) – Pb (34.10) in dry and wet season respectively. Levels of metals measured were higher than their corresponding values reported for soil in the upper continental crusts. Toxic metal (Pb) has its mean concentration ab...

Aerosol chemical composition was characterized during the Central Asian Dust Experiment (CADEX) at Dushanbe (Tajikistan). Aerosol samples were collected during a period of 2 months from March to May 2015 using a high volume DIGITEL DHA-80 sampler on quartz fiber filters. The filters were analyzed for their ionic, trace metals as well as organic and elemental carbon (OC/EC) content. The aerosol mass showed strong variation with mass concentration ranging from 18 μg/m3 to 110 μg/m3. The mineral dust concentrations varied between 0.9 μg/m3 and 88 μg/m3. Days of high aerosol mass loadings were dominated by mineral dust, which made up to about 80% of the aerosol mass while organic matter and inorganic ions made up about 70% of the aerosol mass during days of low aerosol mass loadings. The mineral dust composition showed different trace metal signatures in comparison to Saharan dust with higher Ca content and Ca/Fe ratios twice as high as that observed in Saharan dust. Strong influence of...

Abandoned gold mines are often suggested as potential sources of environmental pollution. Thus, the soils within the area of a gold mine in Lib cice, Czech Republic, were monitored. Elevated element contents were found of As, Cd, Cu, Hg, Pb, and Zn. The risk assessment codes (RACs) indicated high environmental risk from soil Cd, and moderate risk from Zn, whereas the risk of As, Cu, and Pb was low. It was supported by the analysis of 134 samples of aboveground biomass of plants, where the levels of As and Pb were below the detection limit. For Cd, the plant uptake reflected the high mobility of this element, where the bioaccumulation factors (BAFs) varied in range 0.032 (Fragaria vesca) and 1.97 (Circia arvensis). For 11% of samples the BAF values for Cd exceeded 1. For Hg, although the maximum BAF did not exceed 0.37 (Lotus corniculatus), the Hg contents in plants occasionally exceeded the threshold limits for Hg contents in raw feedstuffs. The investigated gold mine does not represent a direct environmental risk, but the fate of Cd and Hg in the soils and plants suggests the necessity of a deeper understanding of the penetration of these elements into the surrounding environment.

The work aimed to evaluate the state of agricultural soil contamination what is important for the gaining of information needed for growing of hygienic safe raw materials and foodstuffs. Metallic pollution of soil in Zemplínska polluted area has begins by accumulation of heavy metals in soil, mainly resulting from location in vicinity of chemical and industrial factories, as well as from many others sources. The pH value development indicates gradual trend of soils acidification, except of alkalic ones reaching up to 20% from total arable soils in Slovakia. Acidification is process, where acidity of abiotic compounds has been increased. Soil reaction is a significant agrochemical property markedly affecting growing and developing of plants, and has directly effect on soil fertility, influencing the ecological conditions for plants and soil microorganisms. The site had been localised with GPS and 5 sampling places had been fixed. From these sites the soil samples were taken from 1 de...

Trace metals in ambient particulate matter and cloud are considered key elements of atmospheric processes as they affect air quality, environmental ecosystems, and cloud formation. However, they are often available at trace concentrations in these media such that their analysis requires high-precision and sensitive techniques. In this study, different analytical methods were applied to quantify trace metals in particulate matter (PM) samples collected on quartz and polycarbonate filters as well as cloud water, using the Total reflection X-Ray Fluorescence (TXRF) technique. These methods considered the measurement of filter samples directly without and with chemical pretreatment. Direct measurements involved the analysis of PM samples collected on polycarbonate filters and cloud water samples after they are brought onto TXRF carrier substrates. The chemical treatment method involved the assessment of different acid digestion procedures on PM sampled on quartz filters. The solutions applied were reverse aqua regia, nitric acid, and a combination of nitric acid and hydrogen peroxide. The effect of cold-plasma treatment of samples on polycarbonate filters before TXRF measurements was also investigated. Digestion with the reverse aqua regia solution provided lower blanks and higher recovery in comparison to other tested procedures. The detection limits of the elements ranged from 0.3 to 44 ng cm -2 . Ca, K, Zn, and Fe showed the highest detection limits of 44, 35, 6, and 1 ng cm -2 , while As and Se had the lowest of 0.3 and 0.8 ng cm -2 , respectively.

Selenium (Se) is a micronutrient of great interest due to the narrow range between its essential and toxic levels. This study was carried out to evaluate the correlations between Se concentrations and soil physicochemical characteristics (sand, silt, clay, organic matter, pH and oxides of Al, Fe and Si) from preserved areas in the Jequitinhonha Valley, Minas Gerais state, Brazil. Total Se was determined in A and B horizons of 12 classes of soils by hydride generation atomic absorption spectrometry (HG AAS) after aqua regia digestion in a microwave oven. Se concentrations in soils ranged from < 0.30 ± 0.03 to 5.97 ± 0.20 mg kg -1 with the highest concentration reported in Spodosol, followed by the weathered soils (Red and Red-Yellow Latosols). No significant differences in Se concentration were observed between A and B horizons, except for Spodosol. The statistical analysis by Pearson's correlation, principal component analysis (PCA) and hierarchical cluster analysis (HCA) showed that Se concentration correlated significantly and positively with Al 2 O 3 (r = 0.76), Fe 2 O 3 (r = 0.57) and clay (r = 0.64) and negatively with SiO 2 (r = -0.76) and sand (r = -0.54). There was no significant correlation with organic matter, pH and silt. Significant Se concentration was verified in weathered soils (Red and Red-Yellow Latosols), which are widely distributed throughout Brazil, and they are often used in agriculture. This study also provides useful data for the preparation of maps of Se distribution.

As Casas da Criança compunham a Obra Social iniciada pelo médico Bissaya Barreto, numa altura em que os índices de pobreza, analfabetismo e mortalidade infantil eram demasiados altos em Portugal. Do ponto de vista educativo e social, aproximavam-se de ações internacionais como La Maison de l&#39;Enfance na França e Casas dei Bambini em Itália. Como parte de uma investigação em desenvolvimento no âmbito do Projeto INOVAR – Roteiros da inovação pedagógica: Escolas e experiências de referência em Portugal no século XX, este trabalho tem por objetivo refletir sobre o caráter inovador das Casas da Criança, suas dinâmicas educativas e de assistência à infância e à família. Propomos reflexões às seguintes perguntas: O que nos diz os documentos sobre o funcionamento e o papel educativo e social das Casas da Criança? Existia inovação? Que tipo? Adotamos uma metodologia qualitativa quanto aos métodos e explicativa quanto aos objetivos, com análise documental dos registos/relatórios de interna...

Top and bottom samples of overbank sediments were collected at 43 sites within a 12 000 km 2 area around the nickel smelter in Nikel and the ore roasting plant at Zapoljarnij, in northwestern Russia. In addition, three detailed overbank profiles were sampled in 10-cm sections from three catchments representing different levels of pollution. All samples were analysed for more than 30 elements by ICP-AES following aqua regia extraction. Results obtained show that overbank sediments represent natural (geogenic) background levels rather well. Although the major pollutants (Co, Cu, Ni and S) are strongly enriched at some places close to industry, overbank sediment is not especially well suited for mapping the extent of airborne contamination in the area. Co, Cu, Ni and S are mobile within the profile collected from the most polluted catchment.

Although the dry ice method used to synthesize exfoliated graphite/graphene is little known and used, it has significant advantages over others: it is low cost, simple, and a large quantity of material can be obtained using some inorganic and highly available acids (which can be reused). Despite the above advantages, the main reason for its incipient development is the resulting presence of magnesium oxide in the final product. In the present work, three different treatments were tested to remove this remnant using some acid chemical leaching processes. Based on the experimental evidence, it was found that using aqua regia, among other chemical mixtures, was the most efficient way of removing such as remnant, the residue being only 0.9 wt.%. A mandatory high-energy mechanical milling stage was necessary during this treatment, in order to expose and dissolve the highly insoluble oxide without secondary chemical reactions on the graphenes. The obtained surface area was 504 m2g-1; this...

The study aimed to come up with a list of specific macroalgae species, which could be used to biomonitor specific metal elements in the coastal waters of East Africa. Water extraction, EDTA, aqua regia extraction and optimized BCR 3-step sequential extracts were used to mimic bioavailable metals under various environmental conditions. The results indicated that Ulva lactuca could be used as a biomonitor to predict BCR 3-step sequential bioavailable Al, Cd, Co, Fe, Mn, Zn and Ni whereas Sargassum species could be used as a biomonitor for BCR 3-step sequential bioavailable Co, Cu, Fe, Mn and Zn. In Sargassum spp. only Co showed significant correlation with concentration in sediment&#39;s aqua regia extracted metals whereas in Ulva lactuca only Al, Co, Cu and Fe showed significant correlation with total metals extracted through aqua regia procedure. This study therefore recommends the use of Ulva lactuca and Sargassum for biomonitoring of Al, Cd, Co, Fe, Mn, Zn, Ni and Co, Cu, Fe, Mn, ...

Currently, environmental risk assessment of metals is based on comparisons of toxicity thresholds against environmental exposure levels measured as total metals, despite the fact that not all heavy metals in the sediments are in bioavailable form to the biota. Analysis was undertaken for nine elements (Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, and Zn) in sediment samples collected at eight sites along the Eastern African Coast following aqua regia extraction (to determine the total quantity of metals) and three-step BCR (Community Bureau of Reference) sequential extraction (to obtain the metal fractionation patterns in the sediments in this region). The results revealed that heavy metal levels at some locations were higher than at others. Cd, Mn and Co were more concentrated in labile fractions compared to the other elements. These metals are easily liberated into overlying water, making them available for biological uptake. More than 62% of the total concentrations of Fe and Zn were present in the residual fraction, being immobile and less bioavailable.

T 8.2 ) in the surface horizons of soil samples from the Balkan mountain vary with - in a wide range of 10.6 cmol.kg -1 to 20.9 cmol.kg -1 . For the soil from the osogovo Mountain, the total cationexchange capacity was higher ranging from 18.4 cmol.kg -1 - 34.4 cmol.kg -1 . t he concentrations of negatively charged strongly acid exchangeable sites ( T CA ) were from 6.0 to 15.5 cmol.kg -1 , for the soil from the Balkan mountain, while for the osogovo Mountain - they were about two times higher - from 12.0 cmol.kg -1 to 27.1 cmol.kg -1 . a similar trend for the exchangeable aluminium ( Al e ) values for the surface horizons of the Balkan mountain soil (from 1.0 cmol.kg -1 to 2.5 cmol.kg -1 ) and of the osogovo Mountain, soil (from 1.6 cmol.kg -1 , to 5.9 cmol.kg -1 ) was established. t he slight increase in the content of Al e in the soil from osogovo Mountain suggests a stronger destruction of a l-bearing minerals, most probably due to isomorphic substitutions. it was found that pod...

Analizy wykaza³y, ¿e badane wody s¹ bardzo dobrej jakooeci, charakteryzuj¹ siê bardzo ma³ymi stê¿eniami oznaczanych sk³adników i spe³niaj¹ wymagania normatywne dla wód pitnych. Osady zbiornika odznaczaj¹ siê wyj¹tkowo ma³ymi zawartooeciami metali ciê¿kich i innych pierwiastków i nie stwarzaj¹ zagro¿enia dla utrzymania dobrej jakooeci wód.

This study produced a highly concentrated gold solution using nanoparticles (NPs) synthesized from sugarcane bagasse as an adsorbent for gold(III) recovery from an aqua regia gold leached lean solution. A 100 kg sample of gold ore collected from a mining site in Iperindo was concentrated. Mineralogical characterization and a fire assay test of the ore were carried out. Atmospheric and agitation leaching were conducted using aqua regia. Sugarcane bagasse NPs were prepared and used to study the gold(III) adsorption kinetics. Gold -loaded sugarcane bagasse NPs were desorbed in a 4 M aqua regia solution. The results revealed that the ore has a low water retention capacity which renders it friable. A microscopic examination established the presence of gold particles and pyrite in the ore. Ore leaching was eminently favoured by agitation yielding a weight loss of 6.3 % when an acid concentration of 4 M was used, the temperature was 90 ºC and the leaching time was 30 minutes. Synthesized nanocellulose was able to adsorb gold(III) from the leach ate optimally with the following process parameters: 14 mL/g of adsorbent, 106.2 minute-long contact time, a temperature of 56 ºC and an agitation rate of 45 rpm when the concentration of leachate was 84 mg/L. The adsorption efficiency of the sugarcane bagasse NPs is comparable with that of commercial activated carbon, namely 92 and 95 %, respectively. The study concluded that NPs synthesized from sugarcane bagasse could be effectively used when upgrading gold and in purification processes.

This study evaluates the impact of mining on soil contamination by conducting a source-specific probabilistic health risk assessment of Potentially Toxic Elements (PTEs) in Southwestern Ghana. Using an Energy-Dispersive X-ray Fluorescence (ED-XRF) spectrometer, 720 soil samples were analyzed for their elemental concentrations. The samples were obtained in 2024 from the B-horizon to provide better accuracy in detecting actual contamination levels linked to illegal mining activities. The PTEs with the highest frequency above their Upper Continental Crustal Averages (UCC) were As(100 %), Ba(13 %), Cr(5.8 %), Pb(2.7 %), Co(2 %), V(2 %), Cu(0.4 %) and Zn(0.4 %). Correlation Coefficient, Self-Organizing Maps (SOM) and Principal Component Analysis (PCA) identified three groups of PTEs, which are geochemically linked elements (Ba, Cr, Cu, Ni, V), anthropogenically influenced As, and a group with low correlations (Co, Pb). Results indicate that anthropogenic activities, such as gold extraction, partly drive As distribution. Geoaccumulation and Pollution Indices reveal varying levels of pollution in As, Cr, and Pb. Health risk assessments, using deterministic and probabilistic methods, found that while non-carcinogenic risks were within safe limits for adults (Hazard Index [HI] < 1), children faced higher risks (HI > 1) for As, Cr, Co, and V. Carcinogenic risks for both groups were within the acceptable threshold (10-4-10-6), with children at greater risk. Ingestion was identified as the primary exposure pathway. The study highlights the higher susceptibility of children to PTE pollution, emphasising the need for interventions to mitigate risks from PTEs.

were defined as 'urban'. They identified a third group (Ca, Fe, Ni, U, etc.) including both those elements likely to have undergone geochemical changes from their original form and those of mixed origin. Similarly, suggested that some metals were of natural origin whereas others could be attributed to industry. found different degrees of association among metals in urban soils of New Orleans, with Pb, Zn, Cr and Cu as dominant metals strongly correlated with one another. They also found positive correlations for Cd, Mn, Ni and V, but these differed from the first group in their distribution within the city. In the case of Pb, found that in a Tyneside catchment in Great Britain the greatest concentrations of Pb were in the more urban and industrialized areas. Recently, a wide survey, URBSOIL, has been initiated in several European cities, including Sevilla, to define the main variables for a comprehensive description of urban soil quality. described a preliminary sampling designed to identify the distribution of heavy metals in the city, and their possible relations with the various soil components. Samples of soils were taken from 0-10 cm and 10-20 cm depth in September to December 2000, and concentrations of metals extracted by 0.05 M EDTA and aqua regia were determined. Some patterns in their spatial distribution suggested moderate pollution, partly related to traffic density, in several parks and gardens, particularly those closer to the historic centre of the city. At such sites, the concentrations of some metals exceeded the limits established elsewhere as acceptable in residential areas ; Ministe`re de l'Environnement du Que´bec, 2001). Marked differences in the EDTA and aqua regia data for Pb, Zn and Cu are attributed to the 'urban' nature of these elements, as concluded by De for urban soils in Madrid. Chromium extracted by EDTA also shows a positive relationship with traffic density. This suggests an urban origin for the more available fractions of this metal. The continuing cycle of construction, use and renewal of urban structures, as well as management and accidental or incidental pollution, lead to far higher rates of change in urban environments than is common elsewhere . To observe any possible seasonal changes due to human activities and to the marked differences in temperature between winter and late spring/early summer in Sevilla, we undertook a new sampling campaign in June and July 2001. Samples of grass were also taken at each sampling point so that we could check whether the metal concentrations in the soil affected those in the plants. In this paper we describe our results and compare them with those of . 1 km N Figure 1 Location of the sampling points within the urban area of Sevilla.

Metals released by the extraction with aqua regia, EDTA, dilute HCl and sequential extraction (SE) by the BCR protocol were studied in urban soils of Sevilla, Torino, and Glasgow. By multivariate analysis, the amounts of Cu, Pb and Zn liberated by any method were statistically associated with one another, whereas other metals were not. The mean amounts of all metals extracted by HCl and by SE were well correlated, but SE was clearly underestimated by HCl. Individual data for Cu, Pb and Zn by both methods were correlated only if each city was considered separately. Other metals gave poorer relationships. Similar conclusions were reached comparing EDTA and HCl, with much lower values for EDTA. Dilute HCl extraction cannot thus be recommended for general use as alternative to BCR SE in urban soils.

Heavy metals and rare earth elements extraction from secondary sources (spent catalyst, industrial solid waster, fly ash) has become an alternative due to environmental issue and shortage of primary sources. Considering those facts study on lanthanum and nickel from spent catalyst using acetic acid has been conducted. The raw material used in this work is spent catalyst from Pertamina Refinery Unit VI, Balongan. The spent catalyst is decarbonized with a heat treatment at 725 °C for 10 minutes before the leaching process. The leaching process was done with varied temperature and acid concentration. The results were assessed by RSM (response surface methodology) and were proved to be a reliable method to depict and analyze the leaching characteristics. The molarity of the citric acid is the most significant independent variables used in the research for lanthanum recovery response. However, based on the Pareto analysis result, there are no significant variables that affect the recover...

Increasing anthropogenic influences on the environment has caused negative changes in natural ecosystems and soil contamination with potentially toxic metals has become a worrying issue at global level, due to the negative impact on the environment and human health. For the purpose of assessing soil contamination in the riparian areas of the Lower Danube River, a number of 144 soil samples were collected twice a year, in the period of June 2013 -December 2016, from 9 monitoring locations, from 0.05 m and 0.3 m depths, and the following indicators: Cr, Cu, Mn, Ni, Pb, Zn, including Ca, Mg, C org , SO 4 2-and humus content have been monitored. The soil was sampled, conserved and analysed according to the European standards in force. Metal concentrations were determined using flame (FAAS) and graphite furnace (GFAAS) atomic absorption spectrometry after "aqua regia" digestion of dried, homogenised and 0.5 mm sieved soil sub-samples. Comparing the average concentration values of the analysed potentially toxic metals, a decreasing tendency following the order Cr>Pb>Ni>Cu>Zn>Mn was observed and by reporting the average values at the normal limits, the order Zn>Cu>Mn>Ni>Pb>Cr of magnitude was obtained. To investigate possible correlations and interdependencies of potentially toxic metals content in the riparian soil, multivariate statistical methods were used. After applying Principal Component Analysis (PCA), 3 main components were identified, with a combined share of about 74 % of the original data-set variance. It was observed that during the monitoring period the average values of the all monitored elements from the studied soils were slightly below the normal reference values, according to the national legislation.

Increasing anthropogenic influences on the environment has caused negative changes in natural ecosystems and soil contamination with potentially toxic metals has become a worrying issue at global level, due to the negative impact on the environment and human health. For the purpose of assessing soil contamination in the riparian areas of the Lower Danube River, a number of 144 soil samples were collected twice a year, in the period of June 2013 � December 2016, from 9 monitoring locations, from 0.05 m and 0.3 m depths, and the following indicators: Cr, Cu, Mn, Ni, Pb, Zn, including Ca, Mg, Corg, SO42- and humus content have been monitored. The soil was sampled, conserved and analysed according to the European standards in force. Metal concentrations were determined using flame (FAAS) and graphite furnace (GFAAS) atomic absorption spectrometry after �aqua regia� digestion of dried, homogenised and 0.5 mm sieved soil sub-samples. Comparing the average concentration values of the analy...

In this study, monthly settleable dust samples were collected in four seasons using the modified crude single open bucket units at five sites within the Vanderbijlpark area. The samples were captured in distilled water medium, filtered, air-dried, weighed to determine mass concentrations, digested with aqua regia acid solution and analyzed for heavy metals by inductively coupled plasma (ICP) 6000 Thermo-Electron modeltechnique. The average ranges of ten metals identified were: zinc (Zn,1.12 – 5.87 mg/L), iron (Fe, 2.25 –8.94 mg/L), chromium (Cr, 0.87 – 3.99 mg/L), titanium (Ti, 0.58 – 3.1 mg/L), manganese (Mn, 2.31 – 9.01 mg/L), lead (Pb, 0.5 – 2.34 mg/L), vanadium (V, 0.94 – 4.18) mg/L), copper (Cu, 0.78 – 3.01 mg/L),  nickel (Ni, 0.7 – 3.64 mg/L) and cadmium (Cd, 1.0 – 2.92 mg/L) respectively. Average daily mass concentrations obtained ranged from 2.42 – 1270 mg/m2/day in autumn, 520 – 1520 mg/m2/day in winter, 142 – 683 mg/m2/day in spring and 156 – 846 mg/m2/day in summer. Both ...

Although the dry ice method used to synthesize turbostratic carbon/graphene is little known and used, it has significant advantages over others, such as the following: it is low cost, simple, and a large quantity of material can be obtained using some inorganic and highly available acids (which can be reused). Despite the above advantages, the main reason for its incipient development is the resulting presence of magnesium oxide in the final product. In the present work, three different treatments were tested to remove this remnant using some acid chemical leaching processes, including hydrochloric acid, aqua regia, and piranha solution. Based on the experimental evidence, it was determined that using aqua regia and combining the leaching process with mechanical milling was the most efficient way of removing such a remnant, the residue being only 0.9 wt.%. This value is low compared to that obtained with the other acid leaching solutions and purification processes (2.8–29.6 wt.%). A...

Soil quality is a critical factor in environmental sustainability, influencing agriculture, biodiversity, and water cycles. Different land-use types, including industrial, urban, agricultural, and natural ecosystems, affect soil properties such as pH, organic carbon, electrical conductivity (EC), and heavy metal contamination. This study examines soil samples from six locations in Nagpur, analyzing key physicochemical parameters. The results show that industrial and urban soils have higher contamination levels, while agricultural soils face nutrient imbalances. The study highlights the need for sustainable soil management policies to maintain soil health.

Legislation limits for risk elements (As, Be, Cd, Co, Cr, Cu, Ni, Pb, V, Zn) in agricultural soil in the Czech Republic are given for the content of elements extracted by aqua regia. This extraction is time consuming and environmentally unfriendly. The regular soil survey is based on Mehlich 3 universal soil extractant and covers the simultaneous determination of macronutrients, sulphur, and micronutrients by inductively coupled plasma optical emission spectrometry (ICP-OES). Our study focused on the possibility to use Mehlich 3 extractant also for preliminary screening for the determination of the risk elements simultaneously with the other elements by the ICP-OES method. Mehlich 3 was confirmed as a reliable screening method for Cd regarding sensitivity, specificity and precision (&gt; 0.8) when the cut-off value of 0.27 mg/kg in Mehlich 3 extracts was used for the prediction of soils to be above or below the legislation limit, which in turn is based on aqua regia extraction. Very...

Heavy metals are unique environmental and industrial pollutants scattered naturally and found almost in all phases of the environment. In certain limited areas in several parts of the world, many people and animals have suffered from several severe diseases caused by trace elements or heavy metal deficiencies and their toxicities, unaware of their existence. The compounds of Pb and Cd are classified as human carcinogens by numerous regulatory agencies. The soil samples digested using the aqua regia method, and concentration quantified through the Inductively coupled plasma mass spectrometry (ICP-MS). In this study, Pb, Cd, and Hg concentrations were recorded high on the landfill site compared to the control site. Their concentration exceeded the permissible limits from WHO. Pb concentration ranges between 0.46ppm to 1.81ppm, Cd range from 0.98ppm and 0.56ppm, and Hg has a high concentration that varies between 6.28ppm and 1.69ppm. On the contrary, the Cu concentration reportable to ...

Au-Ag noble metal wastes represent a wide range of waste types and forms, with various accompanying metallic elements. The presented leaching strategy for Au-Ag contained in circuit boards (PCBs) aims at gaining gold and silver in the metallic form. Application of the proposed ammonium thiosulphate leaching process for the treatment of the above mentioned Au-Ag containing wastes represents a practical, economic and at the same time an ecological solution. The ammonium thiosulphate based leaching of gold and silver from PCBs waste, using crushing as a pretreatment, was investigated. It was possible to achieve 98 % gold and 93 % silver recovery within 48 hours of ammonium thiosulphate leaching. This type of leaching is a better leaching procedure for recovery of gold and silver from PCB waste than the classical toxic cyanide leaching. 84 % Cu, 82 % Fe, 77 % Al, 76 % Zn, 70 % Ni, 90 % Pd, 88 % Pb and 83 % Sn recovery of the accompanying metals was achieved, using sulphuric acid with hydrogen peroxide, sodium chloride and aqua regia. A four steps leaching process gave a very satisfactory yield and a more rapid kinetics for all observed metals solubilization than other technologies.