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Open AccessArticle

Impact Factors on Migration of Molybdenum(VI) from the Simulated Trade Effluent Using Membrane Chemical Reactor Combined with Carrier in the Mixed Renewal Solutions

by

Liang Pei

and

Liying Sun

Toxics 2022, 10(8), 438; https://doi.org/10.3390/toxics10080438 - 31 Jul 2022

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Abstract

Molybdenum is harmful and useful. The efficiency of molybdenum trade effluent treatment is low and it is difficult to extract and recycle. To solve this problem, a novel membrane chemical reactor with mixed organic-water solvent(MCR-OW) had been used for the investigation of impact [...] Read more.

Molybdenum is harmful and useful. The efficiency of molybdenum trade effluent treatment is low and it is difficult to extract and recycle. To solve this problem, a novel membrane chemical reactor with mixed organic-water solvent(MCR-OW) had been used for the investigation of impact factors on the migration characteristics of Mo(VI) in the simulated trade effluent. The novel MCR-OW contains three parts, such as feeding pool, reacting pool and renewal pool. Flat membrane of polyvinylidene fluoride(PVDF) membrane was used in the reacting pool, the mixed solutions of diesel and NaOH with N, N′-di(1-methyl-pentyl)-acetamide(N-503) as the carrier in the renewal pool and the simulated trade effluent with Mo(VI) as feeding solution. The influencing factors of pH and the ion strength in the feeding solutions, the volume ratio of diesel to NaOH solution and N-503 concentration in the renewal solutions were investigated for the testing of the migration efficiency of Mo(VI). It was found that the migration efficiency of Mo(VI) could reach 94.3% in 225 min, when the concentration of carrier(N-503) was 0.21 mol/L, the volume ratio of diesel to NaOH in the renewal pool was 4:3, pH in the feeding pool was 3.80 and the initial concentration of Mo(VI) was 2.50 × 10⁻⁴ mol/L. Moreover, the stability and feasibility of MCR-OW were discussed according to Mo(VI) retention on the membrane and the reuse of the membrane. Full article

(This article belongs to the Special Issue Potentially Toxic Elements Pollution in Urban and Suburban Environments)

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Open AccessArticle

Exploring Soil Pollution Patterns Using Self-Organizing Maps

by

Ilaria Guagliardi

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Aleksander Maria Astel

and

Domenico Cicchella

Toxics 2022, 10(8), 416; https://doi.org/10.3390/toxics10080416 - 25 Jul 2022

Viewed by 256

Abstract

The geochemical composition of bedrock is the key feature determining elemental concentrations in soil, followed by anthropogenic factors that have less impact. Concerning the latter, harmful effects on the trophic chain are increasingly affecting people living in and around urban areas. In the [...] Read more.

The geochemical composition of bedrock is the key feature determining elemental concentrations in soil, followed by anthropogenic factors that have less impact. Concerning the latter, harmful effects on the trophic chain are increasingly affecting people living in and around urban areas. In the study area of the present survey, the municipalities of Cosenza and Rende (Calabria, southern Italy), topsoil were collected and analysed for 25 elements by inductively coupled plasma mass spectrometry (ICP-MS) in order to discriminate the different possible sources of elemental concentrations and define soil quality status. Statistical and geostatistical methods were applied to monitoring the concentrations of major oxides and minor elements, while the Self-Organizing Maps (SOM) algorithm was used for unsupervised grouping. Results show that seven clusters were identified—(I) Cr, Co, Fe, V, Ti, Al; (II) Ni, Na; (III) Y, Zr, Rb; (IV) Si, Mg, Ba; (V) Nb, Ce, La; (VI) Sr, P, Ca; (VII) As, Zn, Pb—according to soil elemental associations, which are controlled by chemical and mineralogical factors of the study area parent material and by soil-forming processes, but with some exceptions linked to anthropogenic input. Full article

(This article belongs to the Special Issue Potentially Toxic Elements Pollution in Urban and Suburban Environments)

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Open AccessArticle

Water-Rock Interaction Processes: A Local Scale Study on Arsenic Sources and Release Mechanisms from a Volcanic Rock Matrix

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Toxics 2022, 10(6), 288; https://doi.org/10.3390/toxics10060288 - 27 May 2022

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Abstract

Arsenic is a potentially toxic element (PTE) that is widely present in groundwater, with concentrations often exceeding the WHO drinking water guideline value (10.0 μg/L), entailing a prominent risk to human health due to long-term exposure. We investigated its origin in groundwater in [...] Read more.

Arsenic is a potentially toxic element (PTE) that is widely present in groundwater, with concentrations often exceeding the WHO drinking water guideline value (10.0 μg/L), entailing a prominent risk to human health due to long-term exposure. We investigated its origin in groundwater in a study area located north of Rome (Italy) in a volcanic-sedimentary aquifer. Some possible mineralogical sources and main mechanisms governing As mobilization from a representative volcanic tuff have been investigated via laboratory experiments, such as selective sequential extraction and dissolution tests mimicking different release conditions. Arsenic in groundwater ranges from 0.2 to 50.6 μg/L. It does not exhibit a defined spatial distribution, and it shows positive correlations with other PTEs typical of a volcanic environment, such as F, U, and V. Various potential As-bearing phases, such as zeolites, iron oxyhydroxides, calcite, and pyrite are present in the tuff samples. Arsenic in the rocks shows concentrations in the range of 17–41 mg/kg and is mostly associated with a minor fraction of the rock constituted by FeOOH, in particular, low crystalline, containing up to 70% of total As. Secondary fractions include specifically adsorbed As, As-coprecipitated or bound to calcite and linked to sulfides. Results show that As in groundwater mainly originates from water-rock interaction processes. The release of As into groundwater most likely occurs through desorption phenomena in the presence of specific exchangers and, although locally, via the reductive dissolution of Fe oxy-hydroxides. Full article

(This article belongs to the Special Issue Potentially Toxic Elements Pollution in Urban and Suburban Environments)

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Open AccessArticle

Influence of Urban Informal Settlements on Trace Element Accumulation in Road Dust and Their Possible Health Implications in Ekurhuleni Metropolitan Municipality, South Africa

by

Innocent Mugudamani

,

Saheed A. Oke

and

Thandi Patricia Gumede

Toxics 2022, 10(5), 253; https://doi.org/10.3390/toxics10050253 - 17 May 2022

Viewed by 588

Abstract

The study was aimed at assessing the influence of urban informal settlement on trace element accumulation in road dust from the Ekurhuleni Metropolitan Municipality, South Africa, and their possible health implications. The concentration of major and trace elements was determined using the wavelength [...] Read more.

The study was aimed at assessing the influence of urban informal settlement on trace element accumulation in road dust from the Ekurhuleni Metropolitan Municipality, South Africa, and their possible health implications. The concentration of major and trace elements was determined using the wavelength dispersive XRF method. The major elements in descending order were SiO₂ (72.76%), Al₂O₃ (6.90%), Fe₂O₃ (3.88%), CaO (2.71%), K₂O (1.56%), Na₂O (0.99%), MgO (0.94%), MnO (0.57%), TiO₂ (0.40%), and P₂O₅ (0.16%), with SiO₂ and P₂O₅ at above-average shale values. The average mean concentrations of 17 trace elements in decreasing order were Cr (637.4), Ba (625.6), Zn (231.8), Zr (190.2), Sr (120.2), V (69), Rb (66), Cu (61), Ni (49), Pb (30.8), Co (17.4), Y (14.4), Nb (8.6), As (7.2), Sc (5.8), Th (4.58), and U (2.9) mg/kg. Trace elements such as Cr, Cu, Zn, Zr, Ba, and Pb surpassed their average shale values, and only Cr surpassed the South African soil screening values. The assessment of pollution through the geo-accumulation index (Igeo) revealed that road dust was moderately to heavily contaminated by Cr, whereas all other trace elements were categorized as being uncontaminated to moderately contaminated. The contamination factor (CF) exhibited road dust to be very highly contaminated by Cr, moderately contaminated by Zn, Pb, Cu, Zr, and Ba, and lowly contaminated by Co, U, Nb, Ni, As, Y, V, Rb, Sc, Sr, and Th. The pollution load index (PLI) also affirmed that the road dust in this study was very highly polluted by trace elements. Moreover, the results of the enrichment factor (EF) categorized Cr as having a significant degree of enrichment. Zn was elucidated as being minimally enriched, whereas all other trace elements were of natural origin. The results of the non-carcinogenic risk assessment revealed a possibility of non-carcinogenic risks to both children and adults. For the carcinogenic risk, the total CR values in children and adults were above the acceptable limit, signifying a likelihood of carcinogenic risk to the local inhabitants. From the findings of this study, it can be concluded that the levels of trace elements in the road dust of this informal settlement had the possibility to contribute to both non-carcinogenic and carcinogenic risks, and that children were at a higher risk than the adult population. Full article

(This article belongs to the Special Issue Potentially Toxic Elements Pollution in Urban and Suburban Environments)

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Open AccessArticle

Discharge Patterns of Potentially Harmful Elements (PHEs) from Coking Plants and Its Relationship with Soil PHE Contents in the Beijing–Tianjin–Hebei Region, China

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Toxics 2022, 10(5), 240; https://doi.org/10.3390/toxics10050240 - 10 May 2022

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Abstract

The Beijing–Tianjin–Hebei (BTH) region in China is a rapid development area with a dense population and high-pollution, high-energy-consumption industries. Despite the general idea that the coking industry contributes greatly to the total emission of potentially harmful elements (PHEs) in BTH, quantitative analysis on [...] Read more.

The Beijing–Tianjin–Hebei (BTH) region in China is a rapid development area with a dense population and high-pollution, high-energy-consumption industries. Despite the general idea that the coking industry contributes greatly to the total emission of potentially harmful elements (PHEs) in BTH, quantitative analysis on the PHE pollution caused by coking is rare. This study collected the pollutant discharge data of coking enterprises and assessed the risks of coking plants in BTH using the soil accumulation model and ecological risk index. The average contribution rate of coking emissions to the total emissions of PHEs in BTH was ~7.73%. Cross table analysis indicated that there was a close relationship between PHEs discharged by coking plants and PHEs in soil. The accumulation of PHEs in soil and their associated risks were calculated, indicating that nearly 70% of the coking plants posed a significant ecological risk. Mercury, arsenic, and cadmium were the main PHEs leading to ecological risks. Scenario analysis indicated that the percentage of coking plants with high ecological risk might rise from 8.50% to 20.00% as time progresses. Therefore, the control of PHEs discharged from coking plants in BTH should be strengthened. Furthermore, regionalized strategies should be applied to different areas due to the spatial heterogeneity of risk levels. Full article

(This article belongs to the Special Issue Potentially Toxic Elements Pollution in Urban and Suburban Environments)

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Open AccessArticle

Potentially Toxic Elements in Urban Soils from Public-Access Areas in the Rapidly Growing Megacity of Lagos, Nigeria

by

Abimbola O. Famuyiwa

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Christine M. Davidson

,

Sesugh Ande

and

Aderonke O. Oyeyiola

Toxics 2022, 10(4), 154; https://doi.org/10.3390/toxics10040154 - 23 Mar 2022

Viewed by 734

Abstract

Rapid urbanization can lead to significant environmental contamination with potentially toxic elements (PTEs). This is of concern because PTEs are accumulative, persistent, and can have detrimental effects on human health. Urban soil samples were obtained from parks, ornamental gardens, roadsides, railway terminals and [...] Read more.

Rapid urbanization can lead to significant environmental contamination with potentially toxic elements (PTEs). This is of concern because PTEs are accumulative, persistent, and can have detrimental effects on human health. Urban soil samples were obtained from parks, ornamental gardens, roadsides, railway terminals and locations close to industrial estates and dumpsites within the Lagos metropolis. Chromium, Cu, Fe, Mn, Ni, Pb and Zn concentrations were determined using inductively coupled plasma mass spectrometry following sample digestion with aqua regia and application of the BCR sequential extraction procedure. A wide range of analyte concentrations was found—Cr, 19–1830 mg/kg; Cu, 8–11,700 mg/kg; Fe, 7460–166,000 mg/kg; Mn, 135–6100 mg/kg; Ni, 4–1050 mg/kg; Pb, 10–4340 mg/kg; and Zn, 61–5620 mg/kg—with high levels in areas close to industrial plants and dumpsites. The proportions of analytes released in the first three steps of the sequential extraction were Fe (16%) < Cr (30%) < Ni (46%) < Mn (63%) < Cu (78%) < Zn (80%) < Pb (84%), indicating that there is considerable scope for PTE (re)mobilization. Human health risk assessment indicated non-carcinogenic risk for children and carcinogenic risk for both children and adults. Further monitoring of PTE in the Lagos urban environment is therefore recommended. Full article

(This article belongs to the Special Issue Potentially Toxic Elements Pollution in Urban and Suburban Environments)

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Open AccessFeature PaperArticle

Vulnerability to Nitrate Occurrence in the Spring Waters of the Sila Massif (Calabria, Southern Italy)

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Toxics 2022, 10(3), 137; https://doi.org/10.3390/toxics10030137 - 12 Mar 2022

Cited by 1 | Viewed by 720

Abstract

Knowledge of spring waters’ chemical composition is paramount for both their use and their conservation. Vast surveys at the basin scale are required to define the nature and the location of the springs and to identify the hydrochemical facies of their aquifers. The [...] Read more.

Knowledge of spring waters’ chemical composition is paramount for both their use and their conservation. Vast surveys at the basin scale are required to define the nature and the location of the springs and to identify the hydrochemical facies of their aquifers. The present study aims to evaluate the hydrochemical facies and the vulnerability to nitrates of 59 springs falling in the Sila Massif in Calabria (southern Italy) and to identify their vulnerability through the analysis of physicochemical parameters and the use of the Langelier–Ludwig diagram. A spatial analysis was performed by the spline method. The results identified a mean value of 4.39 mg NO₃⁻/L and a maximum value of 24 mg NO₃⁻/L for nitrate pollution in the study area. Statistical analysis results showed that the increase in electrical conductivity follows the increase in alkalinity values, a correlation especially evident in the bicarbonate Ca-Mg waters and linked to the possibility of higher nitrate concentrations in springs. These analyses also showed that nitrate vulnerability is dependent on the geological setting of springs. Indeed, the Sila igneous–metamorphic batholith, often strongly affected by weathering processes, contributes to not buffering the nitrate impacts on aquifers. Conversely, anthropogenic activities, particularly fertilization practices, are key factors in groundwater vulnerability. Full article

(This article belongs to the Special Issue Potentially Toxic Elements Pollution in Urban and Suburban Environments)

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Open AccessArticle

Assessment of the Railroad Transport Impact on Physical and Chemical Soil Properties: The Case Study from Zduńska Wola Karsznice Railway Junction, Central Poland

by

Ilona Tomczyk-Wydrych

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Anna Świercz

and

Paweł Przepióra

Toxics 2021, 9(11), 296; https://doi.org/10.3390/toxics9110296 - 06 Nov 2021

Viewed by 615

Abstract

Contamination of the soil and water environment with harmful substances can be associated with many activities carried out on the railway. The problem is particularly relevant to liquid fuel loading and refueling facilities as well as to increased traffic at railway junctions. Studies [...] Read more.

Contamination of the soil and water environment with harmful substances can be associated with many activities carried out on the railway. The problem is particularly relevant to liquid fuel loading and refueling facilities as well as to increased traffic at railway junctions. Studies were conducted in the area of railway junction Zduńska Wola Karsznice in central Poland (Łódź Voivodeship). Soil samples were collected from specific research points: from the inter-railway (A), 5 m from the main track (B), from the embankment—10 m from the main track (C), and from the side track (D), at the depth of 0–5 cm (1) and 20 cm (2). The following analyses were made: granulometric composition, pH in H₂O, and percent content of carbonates (CaCO₃). PHEs were determined in the fractions: 0.25 ≤ 0.5 mm, 0.1 ≤ 0.25 mm, and 0.05 ≤ 0.1 mm: Pb, Cd, Cr, Co, Cu, Ni, Zn, Sr by inductively coupled plasma mass spectrometry technique (ICP-MS/TOF OPTIMass 9500). The objectives of the study were (1) to assess PHEs (potentially harmful elements) contamination of the topsoil level of railway area, (2) to determine the correlation between the concentration of PHEs and the size of the fraction, and (3) to identify the areas (places) where the highest concentrations of PHEs were recorded. Based on the studied parameters, significant differentiation in soil properties of the areas in Zduńska Wola Karsznice was found. The analyses carried out showed that the accumulation of potentially harmful elements was as follows: Cu > Zn > Sr > Pb > Ni > Cr > Co > Cd. The average concentrations of Cu, Zn, Sr, Pb, Ni, Cr, Co and Cd were 216.0; 152.1; 97.8; 64.6; 15.2; 14.4; 3.1 and 0.2 mg·kg⁻¹ d.w., respectively. These contaminations occur in the topsoil layer of the railway embankment, which suggests a railway transport origin. The highest concentrations of PHEs were recorded in samples collected from close to the rails (inter-railway, side track), and in the embankment (10 m from the track) in the very fine sand fraction (0.05 ≤ 0.1 mm). The high accumulation index of copper, cadmium and lead in the surface layer of soil indicate their anthropogenic origin. The results presented in the paper can be used in local planning and spatial development of this area, taking into account all future decisions about ensuring environmental protection, including groundwater and soils. Full article

(This article belongs to the Special Issue Potentially Toxic Elements Pollution in Urban and Suburban Environments)

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