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Antimony (Sb) and lead (Pb) in contaminated shooting range soils: Sb and Pb mobility and immobilization by iron based sorbents, a field study

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... The soil concentrations of contaminants in military zones and war-impacted areas in literature have been typically compared to various types of defined values: (1) background soil concentrations [13,[15][16][17][18][19][20], (2) agricultural soil concentrations [9,17,21,22], (3) generic industrial, urban, and/or recreational soil concentrations [9,13,16,[23][24][25][26][27][28][29], and (4) military range soil concentrations. Some reference values, as well as limits for PTE and CM concentrations in soils, are summarized in Tables 1 and 2, respectively. ...
... The soil concentrations of contaminants in military zones and war-impacted areas in literature have been typically compared to various types of defined values: (1) background soil concentrations [13,[15][16][17][18][19][20], (2) agricultural soil concentrations [9,17,21,22], (3) generic industrial, urban, and/or recreational soil concentrations [9,13,16,[23][24][25][26][27][28][29], and (4) military range soil concentrations. Some reference values, as well as limits for PTE and CM concentrations in soils, are summarized in Tables 1 and 2, respectively. ...
... Numerous studies have reported elevated concentrations of PTEs in soil samples collected from war-impacted areas and military training grounds [6,7,9,13,[15][16][17][19][20][21][22][23][24][26][27][28][29][63][64][65][66][67][68][69][70] with their reported values summarized in Table 3. In order to compare these, a soil pollution index (SPI) of the reviewed areas has been calculated using individual pollution indices (SPIi) for each PTE investigated, which are individual enrichment ratios of these PTEs. ...
Article
Military activities drastically affect soil properties mainly via physical/chemical disturbances during military training and warfare. The present paper aims to review (1) physical/chemical disturbances in soils following military activities, (2) approaches to characterization of contaminated military-impacted sites, and (3) advances in human health risk assessment for evaluating potential adverse impacts. A literature search mainly covering the period 2010-2020 but also including relevant selected papers published before 2010 was conducted. Selected studies (more than 160) were grouped as follows and then reviewed: ~40 on the presence of potentially toxic elements (PTEs), ~20 on energetic compounds (ECs) and chemical warfare agents (CWAs), ~40 on human health risk assessment, and generic limits/legislation, and ~60 supporting studies. Soil physical disturbances (e.g. compaction by military traffic) may drastically affect soil properties (e.g. hydraulic conductivity) causing environmental issues (e.g. increased erosion). Chemical disturbances are caused by the introduction of numerous PTEs, ECs, and CWAs; and are of wide nature. Available generic limits/legislation for these substances is limited, and their content do not always overlap. Among numerous PTEs in military-impacted zones, Pb seems particularly problematic due to its high toxicity, abundance, and persistence. For ECs and CWAs, their highly variable physiochemical properties and biodegradability govern their specific distribution, environmental fate, and transport. Most site characterization include proper spatial/vertical profiling, albeit without adequate consideration of contaminant speciation/fractionation. Human health risk assessment studies generally follow a well-agreed framework; however, the depth/adequacy of its use varies. Generic limits/legislation limited to a few countries do not always include all contaminants of concern, their content don’t overlap, and scientific basis is not always clear. Thus, a comprehensive scientific framework covering a range of contaminants is needed. Overall, contaminant speciation, fractionation, and mobility have not been fully considered in numerous studies. Chemical speciation and bioaccessibility, directly affecting results for risk characterization, should be properly integrated into risk assessment processes for accurate results.
... Sb is most commonly used as a fire retardant in various products such as toys, car-seat covers, light-aircraft-engine covers, and clothing for children and fire fighters (Bagherifam et al., 2019a, Filella et al., 2020, which accounts for around 60% of global Sb consumption. Sb is also frequently used as a glass decolorizer, a catalyst in plastic production, in the manufacture of paint pigments, and in metal alloys for ammunition and battery production (Diquattro et al., 2021;Guo et al., 2018;Okkenhaug et al., 2016). Sb is released into soils and aquatic environments from several sources, the weathering of sulfide ores, leaching from mining wastes, and anthropogenic activities such as smelting, metallurgical operations, and shooting (Diquattro et al., 2020;2021). ...
... Sb concentrations fluctuate under various environmental, geological, and biogeochemical conditions, due to leaching and its continuous release from ores, minerals, and associated rocks (Ahmad et al., 2014;Okkenhaug et al., 2016). Sb exists in clay-mineral deposits and is associated with the organic matter of coal (Qi et al., 2008). ...
... Rom-Sb glasses were recycled and then mixed to produce Rom-Sb-Mn by Romans (Schibille et al., 2017). In modern times, Sb alloys and compounds are also necessary in many manufacturing industries (e.g., semiconductors, motor vehicle batteries, flameproofing materials, pesticides, solder alloys, and fireworks), and in the process of car-tire vulcanization (Bagherifam et al., 2019a;Diquattro et al., 2021;Guo et al., 2018;NHMRC and NRMMC, 2011;Okkenhaug et al., 2016). Lead bullets used in small-arm shooting ranges are hardened by the addition of 2-8% Sb (Mariussen et al., 2017). ...
Article
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Antimony (Sb) is introduced into soils, sediments, and aquatic environments from various sources such as weathering of sulfide ores, leaching of mining wastes, and anthropogenic activities. High Sb concentrations are toxic to ecosystems and potentially to public health via the accumulation in food chain. Although Sb is poisonous and carcinogenic to humans, the exact mechanisms causing toxicity still remain unclear. Most studies concerning the remediation of soils and aquatic environments contaminated with Sb have evaluated various amendments that reduce Sb bioavailability and toxicity. However, there is no comprehensive review on the biogeochemistry and transformation of Sb related to its remediation. Therefore, the present review summarizes: (1) the sources of Sb and its geochemical distribution and speciation in soils and aquatic environments, (2) the biogeochemical processes that govern Sb mobilization, bioavailability, toxicity in soils and aquatic environments, and possible threats to human and ecosystem health, and (3) the approaches used to remediate Sb-contaminated soils and water and mitigate potential environmental and health risks. Knowledge gaps and future research needs also are discussed. The review presents up-to-date knowledge about the fate of Sb in soils and aquatic environments and contributes to an important insight into the environmental hazards of Sb. The findings from the review should help to develop innovative and appropriate technologies for controlling Sb bioavailability and toxicity and sustainably managing Sb-polluted soils and water, subsequently minimizing its environmental and human health risks.
... Numerous studies have focused on metal concentrations and transport due to training activities that can be generally divided into eight main categories: (1) capturing a snapshot of the pointsource contamination (Murray et al., 1997;Basunia and Landsberger, 2001;Clausen et al., 2007a;Clausen and Korte, 2009a), (2) mobility-focused (Johnson et al., 2005;Strømseng et al., 2009;Clausen and Korte, 2009b;Yin et al., 2010;Clausen et al., 2011b;Klitzke et al., 2012;Martin et al., 2014), (3) laboratory-based studies usually concerning toxicity, mobilization, redox processes, sorption, and/or reaction kinetics (Belzile et al., 2001;Rooney et al., 2007;Mitsunobu et al., 2010;Ilgen et al., 2014), (4) speciation characterization (Cao et al., 2003;Hardison et al., 2004;Vantelon et al., 2005;Scheinost et al., 2006;Bednar et al., 2007;Ackermann et al., 2009;Griggs et al., 2010a;Clausen et al., 2010a;Rubio et al., 2017;Bostick et al., 2018;Barker et al., 2020), (5) remediation studies (Jardine et al., 2007;Labare et al., 2004;Migliorini et al., 2004;Griggs et al., 2011;Sanderson et al., 2015;Ogawa et al., 2015Ogawa et al., , 2016; Lewi nska and Karczewska, 2019; Barker et al., 2019b;Larson et al., 2007a), (6) animal toxicity (Braun et al., 1997;Dvorak et al., 2020), (7) microbial/plant impacts (Rooney et al., 1999;Labare et al., 2004;Migliorini et al., 2004;Robinson et al., 2008;Pourrut et al., 2011;Evangelou et al., 2012;Busby et al., 2019), or (8) large-scale, comprehensive approach highlighting multiple categories, such as laboratory-based remediation trials (Okkenhaug et al., 2016;Larson et al., 2007b) or fieldscale speciation characterization coupled with remediation efforts (Barker et al., 2019a;Larson et al., 2016). ...
... local retention) or desorption of a given species to soils may provide conditions that promote mobility (i.e. potential off site migration) for other species, particularly for cation metals (Pb) versus oxyanion metalloids (Sb) (Jardine et al., 2007;Okkenhaug et al., 2011Okkenhaug et al., , 2016Ogawa et al., 2015;Doherty et al., 2017;Barker et al., 2019a). Since military training activities occur all over the world and during all seasons there is a wide range in environmental and biogeochemical conditions and processes that govern the ultimate fate of metals in training range soils and waters. ...
... Concentrations of Sb at sport shooting ranges often exceed crustal abundances of 0.2 mg/kg (Onishi and Sandell, 1955) and naturally occurring dissolved Sb concentrations have been estimated at less than 0.1 mg/L for unpolluted waters (Filella et al., 2002). Antimony in soils at sport shooting ranges have been documented to range from 7.40 ± 6.19 to 325 ± 90 mg/kg (Sanderson et al., 2015), pore waters from 19 to 349 mg/L (Okkenhaug et al., 2016), and Sb has also been found to infiltrate groundwater and local surface water, 11 ± 2 mg/L and 7.4 ± 0.1 mg/L, respectively (Okkenhaug et al., 2018). ...
Article
Full-text available
The deposition of metals into the environment as a result of military training activities remains a long-term concern for Defense organizations across the globe. Of particular concern for deposition and potential mobilization are antimony (Sb), arsenic (As), copper (Cu), lead (Pb), and tungsten (W), which are the focus of this review article. The fate, transport, and mobilization of these metals are complicated and depend on a variety of environmental factors that are often convoluted, heterogeneous, and site-dependent. While there have been many studies investigating contaminant mobilization on military training lands there exists a lack of cohesiveness surrounding the current state of knowledge for these five metals. The focus of this review article is to compile the current knowledge of the fate, transport, and ultimate risks presented by metals associated with different military training activities particularly as a result of small arms training activities, artillery/mortar ranges, battleruns, rocket ranges, and grenade courts. From there, we discuss emerging research results and finish with suggestions of where future research efforts and training range designs could be focused toward further reducing the deposition, limiting the migration, and decreasing risks presented by metals in the environment. Additionally, information presented here may offer insights into Sb, As, Cu, Pb, and W in other environmental settings.
... Stabilizers, earthworm, root exudates, leaching process and so on could affect the extractability of heavy metal. For instance, stabilizers helped to immobilize heavy metals and reduce their extractability, which were positive for soil remediation (Gudny et al., 2016;Yao et al., 2016). Earthworm activity and root exudates contributed to heavy metal activation (Udovic and Lestan, 2007), providing a new way for plants to extract heavy metals. ...
... Overall, the mechanism of material on soil heavy metal can be summarized as precipitation, adsorption, complexation, chelation, cation exchange (Gudny et al., 2016). Precipitation is the process by which heavy metal ions precipitated as hydroxides or stable salts on the surface of the stabilizers, typically, part of the Cu ion and Pb ion on the surface of the biochar was combined with OH − and PO 4 3− (Rizwan et al., 2016). ...
... In simple terms, complexation and chelation were the processes by which heavy metal ions form stable compounds with organic matter and soil components. For example, in soil porewater, dissolved Pb was mainly complex-bound with dissolved organic carbon (DOC) (Gudny et al., 2016), while on the biochar surface organometallic interactions and π-π donor-acceptor interactions occurred (Vithanage et al., 2018). However, organic root exudates could activate heavy metals and facilitate migration (Shi et al., 2004). ...
Article
The interaction between multi-walled carbon nanotubes (MWCNTs) and soil heavy metals was rarely studied. With the convenience of detecting multiple metal elements by ICP-AES, this paper examined the potential effectiveness of MWCNTs on extractability of antimony (Sb) and cadmium (Cd) in contaminated soil. Three-step sequential extraction procedure, toxicity characteristic leaching procedure, bioaccessibility and CaCl2 single extraction were employed to evaluate Sb and Cd speciations and their extractabilities. According to our results, only at low Sb content level of 100 mg/kg, antimony bioavailability reduced with MWCNTs addition of 0.3% and 0.9% by 22.97% and 20.74%, respectively, which might due to the increase of adsorption point, nevertheless, the excess Sb(OH)6⁻ was not adsorbed more efficiently. Secondly, due to the difference in effective specific surface area, only under the condition of high content level and MWCNTs addition of 0.1%, the mild acid-soluble fraction increased at most by 15.40% for Sb and 9.40% for Cd, respectively. However, in terms of TCLP-extractable Sb and Cd and CaCl2-extractable Sb and Cd, no significant, continuous, regular extractability pattern were found. Overall, MWCNTs were selective on extractability of soil heavy metals due to mechanisms of physical adsorption. This paper provides data reference for the interaction between MWCNTs and soil heavy metals extractability.
... Likewise a small SRSL of Canadian Force Bases also reported high concentrations of potentially toxic elements, which were quantified as 27,100 mg kg −1 Pb, 7720 mg kg −1 Cu, 1080 mg kg −1 Zn, and 570 mg kg −1 Sb (Laporte-Saumure 573 2. Bioremediation of organic pollutants et al., 2011). A soil of shooting range located in Switzerland exhibited the highest concentration of Sb (8230 mg kg −1 ) (Robinson et al., 2008), while the lowest concentration of Sb (12 mg kg −1 ) was recorded in SRSL from Norway (Okkenhaug et al., 2016). Similarly the concentrations of Pb and Sb in SRSL reached up to 29,540 and 89.6 mg kg −1 , respectively (Lewińska and Karczewska, 2019b). ...
... Due to the amphoteric properties of their variably charged surface groups, Fe-oxyhydroxides, As and Mn oxides, can form surface complexes with both cations and anions (Okkenhaug et al., 2016;Almås et al., 2019), having, therefore, a potential for stabilization of both Sb and Pb. In alkaline soils, they can adsorb cations, but their CEC is relatively low and can be neglected at the presence of organic matter and clay minerals. ...
... Soil amendment with Fe oxides also considerably reduces the mobility of Pb, Cu, and Zn in SRS (Mariussen et al., 2015(Mariussen et al., , 2017. While the solubility of Sb in those soils may be controlled both by sorption on Fe-oxyhydroxides and precipitation of secondary minerals, immobilization of Pb and other metals by Fe-oxyhydroxides is controlled rather by sorption and occludation processes (Alloway, 2013;Okkenhaug et al., 2016). ...
Chapter
Military firing or shooting ranges exhibit the most significant environmental concern of the current era. The copresence of diverse types of organic (TNT, RDX, and HMX) and inorganic pollutants (Pb, Cu, Cd, Ni, Cr, Zn, As, and Sb) can cause endless damage to the environment. Therefore the presence of these pollutants at a single site makes them a good option for studying the behavior and transformation mechanisms of both types of pollutants. Traditional remediation approaches can render the toxicity of pollutants at these sites. However, they are not preferred due to their high cost, low public acceptability, indirect harm to the environment, and more labor involvement. Contrary to it, such sites that are highly contaminated with organic pollutants, metals, and metal(loid)s can be managed by using various approaches like bioremediation, bacterial degradation/transformation, phytoremediation, phytoextraction, immobilization, and combination of these techniques. Likewise the sites polluted with organic explosives, strategies like phytotransformation, bioremediation, bioaugmentation, and photolysis are recommended, which can reduce the levels of toxicants by their transformation, degradation, and conversion into nontoxic forms, whereas phytoextraction, bacterial transformation, in situ immobilization, and phytostabilization can deem the risk of inorganic pollutants at such sites. By undertaking these techniques and management practices, the harm to the environment from these polluted shooting ranges can be scaled down.
... Numerous studies have focused on metal concentrations and transport due to training activities that can be generally divided into eight main categories: (1) capturing a snapshot of the pointsource contamination (Murray et al., 1997;Basunia and Landsberger, 2001;Clausen et al., 2007a;Clausen and Korte, 2009a), (2) mobility-focused (Johnson et al., 2005;Strømseng et al., 2009;Clausen and Korte, 2009b;Yin et al., 2010;Clausen et al., 2011b;Klitzke et al., 2012;Martin et al., 2014), (3) laboratory-based studies usually concerning toxicity, mobilization, redox processes, sorption, and/or reaction kinetics (Belzile et al., 2001;Rooney et al., 2007;Mitsunobu et al., 2010;Ilgen et al., 2014), (4) speciation characterization (Cao et al., 2003;Hardison et al., 2004;Vantelon et al., 2005;Scheinost et al., 2006;Bednar et al., 2007;Ackermann et al., 2009;Griggs et al., 2010a;Clausen et al., 2010a;Rubio et al., 2017;Bostick et al., 2018;Barker et al., 2020), (5) remediation studies (Jardine et al., 2007;Labare et al., 2004;Migliorini et al., 2004;Griggs et al., 2011;Sanderson et al., 2015;Ogawa et al., 2015Ogawa et al., , 2016; Lewi nska and Karczewska, 2019; Barker et al., 2019b;Larson et al., 2007a), (6) animal toxicity (Braun et al., 1997;Dvorak et al., 2020), (7) microbial/plant impacts (Rooney et al., 1999;Labare et al., 2004;Migliorini et al., 2004;Robinson et al., 2008;Pourrut et al., 2011;Evangelou et al., 2012;Busby et al., 2019), or (8) large-scale, comprehensive approach highlighting multiple categories, such as laboratory-based remediation trials (Okkenhaug et al., 2016;Larson et al., 2007b) or fieldscale speciation characterization coupled with remediation efforts (Barker et al., 2019a;Larson et al., 2016). ...
... local retention) or desorption of a given species to soils may provide conditions that promote mobility (i.e. potential off site migration) for other species, particularly for cation metals (Pb) versus oxyanion metalloids (Sb) (Jardine et al., 2007;Okkenhaug et al., 2011Okkenhaug et al., , 2016Ogawa et al., 2015;Doherty et al., 2017;Barker et al., 2019a). Since military training activities occur all over the world and during all seasons there is a wide range in environmental and biogeochemical conditions and processes that govern the ultimate fate of metals in training range soils and waters. ...
... Concentrations of Sb at sport shooting ranges often exceed crustal abundances of 0.2 mg/kg (Onishi and Sandell, 1955) and naturally occurring dissolved Sb concentrations have been estimated at less than 0.1 mg/L for unpolluted waters (Filella et al., 2002). Antimony in soils at sport shooting ranges have been documented to range from 7.40 ± 6.19 to 325 ± 90 mg/kg (Sanderson et al., 2015), pore waters from 19 to 349 mg/L (Okkenhaug et al., 2016), and Sb has also been found to infiltrate groundwater and local surface water, 11 ± 2 mg/L and 7.4 ± 0.1 mg/L, respectively (Okkenhaug et al., 2018). ...
Technical Report
Full-text available
The deposition of metals into the environment as a result of military training activities remains a longterm concern for Defense organizations across the globe. Of particular concern for deposition and potential mobilization are antimony (Sb), arsenic (As), copper (Cu), lead (Pb), and tungsten (W), which are the focus of this review article. The fate, transport, and mobilization of these metals are complicated and depend on a variety of environmental factors that are often convoluted, heterogeneous, and site dependent. While there have been many studies investigating contaminant mobilization on military training lands there exists a lack of cohesiveness surrounding the current state of knowledge for these five metals. The focus of this review article is to compile the current knowledge of the fate, transport, and ultimate risks presented by metals associated with different military training activities particularly as a result of small arms training activities, artillery/mortar ranges, battle runs, rocket ranges, and grenade courts. From there, we discuss emerging research results and finish with suggestions of where future research efforts and training range designs could be focused toward further reducing the deposition, limiting the migration, and decreasing risks presented by metals in the environment. Additionally, information presented here may offer insights into Sb, As, Cu, Pb, and W in other environmental settings.
... More, specifically, the chemical immobilisation is an affordable and inexpensive technique, which can involve the application of soil amendments to adsorb, reduce, complex or co-precipitate PTEs (Arenas-Lago et al., 2016;Ogawa et al., 2015;Okkenhaug et al., 2016;Sanderson et al., 2018;Souza et al. 2020). ...
... Sequential chemical extractions have been previously used to assess the behaviour PTEs, such as Pb and Sb, on shooting ranges soils, and the effectiveness of soil amendments to reduce metal availability (Fayiga and Saha, 2017;Okkenhaug et al., 2016;Sanderson et al., 2018;Yan et al., 2016). As our results ...
... show, ours NMs amendments can favour the immobilisation of the different PTEs in less available forms, as indicated by different authors with the addition of CPNs (Liu and Zhao, 2013;Ogawa et al., 2015;Zhang et al., 2010), FeNs (Liu and Zhao, 2007;Ogawa et al., 2015;Xu et al., 2016) and iron-based sorbents (Okkenhaug et al., 2016). the shooting range soils. ...
Article
Full-text available
Shooting range facilities in military areas have been indicated as a hotspot of land degradation with high contents of Potentially Toxic Elements (PTEs). Currently, based on the new nanomaterials with specific characteristics, nanoremediation technologies are used to immobilise and to reduce the availability of PTEs in field and laboratory conditions. In this study, the effects of nano-hydroxyapatite and/or hematite on PTEs immobilisation (As, Cd, Cu, Pb, Sb and Zn) in military shooting range soils were assessed through the measure of available and leachable forms with three single-extractions: calcium chloride (0.01M CaCl2), low molecular weight organic acids (10mM LMWOAs) and toxicity characteristic leaching procedure (TCLP). A sequential chemical extraction was used to determine the distribution of the PTEs in the different geochemical phases of the soils before and after the nanomaterial treatments. Results showed that the availability of PTEs decreased, especially for Pb (40-95%) and Zn (50-99%) after nanomaterial treatments. When both nanomaterial (hydroxyapatite + hematite) were combined, the immobilisation rate improved. However, when each nanomaterial was added individually to the soils, some elements, such as, Cu or Sb, showed a slight increment of their mobilisation. The sequential chemical extraction showed that the highest percentage of PTEs were mainly in the residual fraction before and after adding nanomaterials, being even higher in soils after the nanomaterial treatments. Likewise, the mobile fractions decreased after the treatment with nanomaterials. Our findings suggest that nanoremediation techniques improve the soil conditions, but they should be used carefully to avoid mobilisation of non-target PTEs or unexpected potentially impacts for soil biota.
... Roots serve as a barrier for plant uptake. (Bi et al., 2006;Okkenhaug et al., 2016;Rinklebe et al., 2016c) Sb -Oxidation states: −3, 0, 3, 5 (mainly found as +3 and + 5). Sb(+3) is predominant under low redox conditions (Eh < 50 mV), whereas Sb(+5) is less stable in reducing environments. ...
... -Competing anions: Sulfate, phosphate, and organic anions. (Okkenhaug et al., 2016;Shaheen et al., 2014b) V -Oxidation states: +2 to +5. Under moderately reducing and oxidizing conditions, V(+4) and V(+5) species are dominant. ...
Article
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Soil contamination by potentially toxic elements (PTEs) has led to adverse environmental impacts. In this review, we discussed remediation of PTEs contaminated soils through immobilization techniques using different soil amendments with respect to type of element, soil, and amendment, immobilization efficiency, underlying mechanisms, and field applicability. Soil amendments such as manure, compost, biochar, clay minerals, phosphate compounds, coal fly ash, and liming materials are widely used as immobilizing agents for PTEs. Among these soil amendments, biochar has attracted increased interest over the past few years because of its promising surface properties. Integrated application of appropriate amendments is also recommended to maximize their use efficiency. These amendments can reduce PTE bioavailability in soils through diverse mechanisms such as precipitation, complexation, redox reactions, ion exchange, and electrostatic interaction. However, soil properties such as soil pH, and clay, sesquioxides and organic matter content, and processes, such as sorption/desorption and redox processes, are the key factors governing the amendments' efficacy for PTEs immobilization in soils. Selecting proper immobilizing agents can yield cost-effective remediation techniques and fulfill green and sustainable remediation principles. Furthermore, long-term stability of immobilized PTE compounds and the environmental impacts and cost effectiveness of the amendments should be considered before application.
... The long-term performances were then compared with literature data obtained from long-term field studies (Table 3). Due to the lack of field evidence for Sb (except a 3-year field trial by Okkenhaug et al. (2016)), only As immobilization performances were plotted for comparison (Fig. 5d). Most field studies have only monitored the aging process for up to 3 years, making it hard for direct comparison because this quantitative aging method simulated a single treatment for 4 years. ...
... Although often criticized for aging-associated risks, Solidification/ Stabilization (S/S) is still the most widely used contaminated site Okkenhaug et al. (2016) metal(loid) remediation method worldwide. In China, for example, its adoption rate had even reached 48.5% (Shen et al., 2019a). ...
Article
Aging is an inevitable natural process, leading to faded performances of soil amendments. Understanding long-term aging features is crucial for the risk management of contaminated soil. In this study, a novel quantitative aging method, namely, the “soil coin” method, was developed, which can simulate the effects of natural aging on metal(loid) immobilization performances. To better depict the aging features, two models on the basis of conditional probability-induced failure were developed. To effectively immobilize soil arsenic (As) and antimony (Sb), magnesium (Mg) and iron (Fe) oxides were simultaneously introduced to either fresh or pre-oxidized biochar via a facile method. Although post-application aging is harmful, pre-aging (i.e., pre-oxidation using H2O2) in turn served as an effective means to introduce more metal oxides, thereby rendering better short-term and long-term effectiveness for metalloid immobilization. Experimental and modeling approaches suggested that precipitation accounted for long-term immobilization, while a constant aging rate is the key feature for a promising soil amendment. It is suggested that to further calibrate this method and better understand the immobilization performances in the long run, more evidence from the field is needed.
... However, there are substantial gaps in our understanding of the mechanisms by which coupled biotic and abiotic processes involved in the redox transformations of Fe and S determine the speciation/mobility and fate of Sb in natural systems. Both Fe(III) and Fe(II) minerals are highly reactive in geological systems and have been shown to participate in sorption and redox reactions with Sb (Tighe et al., 2005;McComb et al., 2007;Mitsunobu et al., 2010;Shangguan et al. 2015Shangguan et al. , 2016Okkenhaug et al., 2016;. Sb adsorption to iron minerals, such as Fe(III) oxides and jarosite, affects the mobility of Sb and is dependent on redox conditions, Sb speciation, and pH Bolanz et al., 2013;Vithanage et al., 2013;Qi and Pichler 2017;. ...
... Sb adsorption to iron minerals, such as Fe(III) oxides and jarosite, affects the mobility of Sb and is dependent on redox conditions, Sb speciation, and pH Bolanz et al., 2013;Vithanage et al., 2013;Qi and Pichler 2017;. In particular, Sb(III) adsorbs strongly to Fe(III) oxides in soil and groundwater systems (Shangguan et al. 2015(Shangguan et al. , 2016Okkenhaug et al., 2016;, which can lead to oxidation to Sb(V) (Belzile et al., 2001;Leuz et al., 2006;Qi and Pichler 2016). Compared to Fe(III) oxides, little is known regarding the interactions of Sb with Fe(II)-bearing minerals. ...
Article
Full-text available
Increasing use and mining of antimony (Sb) has resulted in greater concern involving its fate and transport in the environment. Antimony(V) and (III) are the two most environmentally relevant oxidation states, but little is known about the redox transitions between the two in natural systems. To better understand the behavior of antimony in anoxic environments, the redox transformations of Sb(V) were studied in biotic and abiotic reactors. The biotic reactors contained Sb(V) (2 mM as KSb(OH)6), ferrihydrite (50 mM Fe(III)), sulfate (10 mM), and lactate (10 mM), that were inoculated with sediment from a wetland. In the abiotic reactors, The interaction of Sb(V) with green rust, magnetite, siderite, vivianite or mackinawite was examined under abiotic conditions. Changes in the concentrations of Sb, Fe(II), sulfate, and lactate, as well as the microbial community composition were monitored over time. Lactate was rapidly fermented to acetate and propionate in the bioreactors, with the latter serving as the primary electron donor for dissimilatory sulfate reduction (DSR). The reduction of ferrihydrite was primarily abiotic, being driven by biogenic sulfide. Sb and Fe K-edge X-ray absorption near edge structure (XANES) analysis showed reduction of Sb(V) to Sb(III) within 4 weeks, concurrent with DSR and the formation of FeS. Sb K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy analysis indicated that the reduced phase was a mixture of S- and O-coordinated Sb(III). Reduction of Sb(V) was not observed in the presence of magnetite, siderite, or green rust, and limited reduction occurred with vivianite. However, reduction of Sb(V) to amorphous Sb(III) sulfide occurred with mackinawite. These results are consistent with abiotic reduction of Sb(V) by biogenic sulfide and reveal a substantial influence of Fe oxides on the speciation of Sb(III), which illustrates the tight coupling of Sb speciation with the biogeochemical cycling of S and Fe.
... Pain et al. (2019) reported that tens of thousands of tons of Pb(II) have been released into the environment around military sites annually in Europe. Additionally, it is reported that the total Sb(V) deposition reaches 12 tons annually in small shooting ranges in Norway, and Pb(II) and Sb(V) concentrations of 840 and 20 μg/L, respectively, in runoff water exceeded the background levels (Okkenhaug et al. 2016). Previous studies also revealed that precipitation and snow melting period could increase the concentrations of Pb(II) and Sb(V) in surrounding aqueous systems (Heier et al. 2009;Strømseng et al. 2009). ...
... Earlier, Kameda et al. (2017) provided the evidence that ferrihydrite-gypsum sorbent can simultaneously remove Pb(II) and As(V) from contaminated solution. Moreover, the application of ferric oxyhydroxide powder-limestone to the Pb-Sb-contaminated area resulted in obvious reduction of Pb(II) and Sb(V) concentrations in water pores by 97% and 66%, respectively (Okkenhaug et al. 2016). Therefore, it is reasonable to suggest that the combination of PG and iron (hydro)oxides could be an efficient and inexpensive method for sequestrating Pb(II) and Sb(V) from water simultaneously. ...
Article
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The serious environmental risks caused by Pb(II) and Sb(V) co-contamination increase the need for their efficient and simultaneous removal. In this study, the remediation feasibility by Fe-doped phosphogypsum (FPG) was elucidated for single systems with Pb or Sb pollutant and coexisting systems with both from water. As for single systems, Fe doping effectively enhanced the Pb(II) removal performance by phosphogypsum (PG) at low Pb(II) concentrations of below 100 mg/L via the combination of precipitation and complexation. The optimal removal rate of Sb(V) by FPG increased by 2.08–3.31 times as compared to that of by PG (10–120 mg/L), mainly due to the strong affinity of iron hydroxyl (≡Fe–O–H) towards Sb(V). Compared with the single systems, the coexistence greatly enhanced the Pb(II) and Sb(V) removal performance by FPG, and the interaction behavior between Pb(II) and Sb(V) on the FPG was concentration dependent. Briefly, the sorption of FPG controlled the elimination of low coexisting concentrations of Pb(II) and Sb(V), whereas the co-precipitation process between Pb(II) and Sb(V) predominated with high ions concentration. The significant synergistic effects were found during the removal of Pb(II) and Sb(V) on FPG in the coexisting system, which mainly attributed to precipitation, bridging complexation and electrostatic attraction. Considering the advantages such as facile preparation, low cost and high removal capacity, FPG is a promising material to uptake Pb(II) and/or Sb(V) from contaminated water.
... Antimony (Sb) is a naturally occurring metalloid capable of forming toxic products, is a suspected carcinogen (Gebel 1997;ATSDR 2019) and has been classed as a priority substance (ATSDR, 2017). Antimony can be enriched in soils as a result of the mobilization of antimony from minerals and waste antimony ore and activities including mining, mineral smelting and the use of drugs and pesticides (Okkenhaug et al. 2016;Wang et al. 2011), allowing interaction with the wider hydrological, biological and surface environment (Filella et al. 2007). In addition, Sb, As, Pb, Cd and Hg frequently coexist in antimony ore deposits (Terry et al. 2015) and the mining of Sb can cause the release of significant amounts of coexisting elements enhancing the potential hazard of the location. ...
... A number of examples of mining locations of interest include on the Mediterranean coast in the Marseille region of France, the Hillgrove Sb-Au mine in New South Wales, Australia, and the Xikuangshan (XKS) Sb mine in Hunan, China, which have all been linked to the release of significant amounts of co-occurring toxic elements impacting on the local environment (Okkenhaug et al. 2016;Telford et al. 2009), with limited understanding of wider impact of co-contamination with toxic elements (Gebel 1997) . ...
Article
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Elevated soil concentrations of antimony (Sb) and co-contaminants are frequently encountered where antimony has been mined on a large scale. For instance, the Xikuangshan antimony mine in central South China has sustained, over many centuries, dispersed and spatially variable input of toxic elements into the soil ecosystem. We utilized this unique environment to assess the impact of geochemical conditions on soil microbiology. Geochemical conditions were assessed by monitoring absolute and available fractions of toxic elements and disrupted soil properties. Soil microbiology was studied by high-throughput sequencing and statistical analysis, including principle component analysis and canonical correspondence analysis. Results show that Sb concentrations were ranged from 970 to more than 24,000 mg/kg. As concentrations were three times higher than the regional background values and ten times higher for Pb, 590 times higher for Cd and 30 times higher for Hg. About 5–10% of the total soil Sb was environmentally mobile. Microbial diversity was high, and soil properties such as pH, organic matter, iron and sulfate controlled the absolute microbial activity. We identified strong positive and negative correlations with specific bacterial taxonomic groups which show: (1) an intolerance of available fractions for all elements, e.g., Gemmatimonas, Pirellula, Spartobacteria; (2) a good tolerance of available fractions for all elements, e.g., Povalibacter, Spartobacteria; and (3) a mixed response, tolerating available Sb, Hg and Cd and inhibition by As, Pb, e.g., Escherichia/Shigella and Arthrobacter, and in reverse, e.g., Gemmatimonas and Sphingomonas. The site hosts great diversity dominated by Gram-negative organisms, many with rod (bacillus) morphologies but also some filamentous forms, and a wide range of metabolic capabilities: anaerobes, e.g., Saccharibacteria, metal oxidizing, e.g., Geobacter, chemoautotrophs, e.g., Gemmata, and sulfur reducing, e.g., Desulfuromonas. The bioremediation potential of Arthrobacter and Escherichia/Shigella for Sb control is highlighted.
... Both Pb and Sb are sensitive to oxidation-reduction (redox) conditions and changes in soil chemistry and are known to form different metal species that control their mobility in soil (Johnson et al. 2005;Clausen et al. 2011). Studies have shown that pH, redox environment, presence of organic matter and iron/manganese oxides in soils, and speciation significantly affect the overall solubility and mobility of Pb and Sb (Vantelon et al. 2005;Scheinost et al. 2006;Ackermann et al. 2009;Okkenhaug et al. 2016). Understanding the behavior of Pb and Sb in soil and soil solution as a function of site parameters and soil remediation is integral to assessing the overall fate and transport of Pb and Sb on-site and estimating the potential for off-site migration and infiltration into groundwater. ...
... Iron addition was selected for this study as a potential remediation option because previous studies have shown it to have a natural affinity for immobilizing both Pb and Sb at a variety of pH values (Scheinost et al. 2006;Ackermann et al. 2009;Okkenhaug et al. 2016). Iron (III) hydroxide was chosen for our tests due to its high surface area and because it does not alter solution pH upon addition, unlike other iron-based amendments, particularly iron (II). ...
Technical Report
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The results and documentation in this report summarize work supporting the Joint Base Cape Cod Camp Edwards Small-Arms Ranges (JBCC SARs) assessment of the potential for lead (Pb) and antimony (Sb) to migrate in soil and soil solutions. Batch studies were performed in an effort to interpret field results for metal concentrations at Camp Edwards SARs and to determine potential remediation strategies that limit both Pb and Sb. The batch study showed phosphate and iron treatments had minimal to no impact on Pb and Sb dissolution. However, the lime treatment significantly decreased the dissolution of Sb while increasing the dissolution of Pb. Dissolved metal concentrations decreased over the course of the 48-hour experiment regardless of treatment.
... In nature, pollutants often associate with Fe minerals (Fritzsche et al., 2011;Ma et al., 2019a;Ma et al., 2019b;Okkenhaug et al., 2016;Ouyang et al., 2020). Compared to GT, FH has a larger specific surface area and, hence, a higher affinity to pollutants (Das et al., 2013;Sajih et al., 2014). ...
Article
The dispersities of goethite nanoparticles (GTNPs) and ferrihydrite nanoparticles (FHNPs) affect the transport and retention of nanoparticle-associated contaminants. However, the effects of interaction on nanoparticle stability under varying environmental conditions have not been previously investigated. This study utilized settling experiments, a semi-empirical model, and the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory to study the homo-aggregation and hetero-aggregation of GTNPs and FHNPs. The pure system of GTNPs tended to aggregate more easily than that of FHNPs, especially under the conditions of high pH (7.0–9.0), high ionic strength (IS, 10 mM), and low concentrations of humic acid (HA) (2 mg L⁻¹). This aggregation was attributed to the elongated morphology of GTNPs, which contributed to surface heterogeneity. The GTNPs and FHNPs mixtures rapidly coagulated, particularly under the surface-charge disequilibrium caused by an increase in negative charges or IS. Hetero-aggregation increased with increase in the GTNPs ratio, indicating that the elongated GTNPs dominated the coagulation of the Fe mineral nanoparticle mixture, which was attributed to the surface heterogeneity and high probability collisions between the GTNPs. Although DLVO neglects the influence of heterogeneity on the nanoparticle surfaces, SEM revealed that hetero-aggregation of GTNPs and FHNPs occurred. The results obtained in this study provide novel and valuable insights into the behaviors of GTNPs and FHNPs mixtures and suggest that during the gradual transformation of FHNPs to GTNPs in soil or aquatic environments, the hetero-aggregation of GTNPs and FHNPs may be enhanced, thus promoting contaminant immobilization.
... To date, phosphate (PO 4 )-based amendments (Griggs et al. 2011), iron-based sorbents (Okkenhaug et al. 2016), and mussel shell and cow bone (Ahmad et al. 2014) have been employed as soil amendments for Sb immobilization in soils. Recently, the use of biochar as a soil amendment is becoming increasingly popular (Zheng et al. 2012), partly due to its potential function in soil carbon sequestration (Lehmann et al. 2011) as well as fertility and structure improvement. ...
Article
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Biochar was a kind of restoration material for soil pollution. Investigation about biochar amendment on the Sb transformation in rice plants is scarce. The pot experiment was conducted to evaluate the impact of biochar on the iron plaque formation in Sb-contaminated soil, and the translocation and accumulation of Sb in rice seedings. After the straw and husk biochar amendments (5% by weight), the levels increased on average by 20.0% and 16.0% for exchangeable Sb in soil, and by 233.3% and 74.8% for soluble Sb in pore water, respectively; but the residual fractions of Sb decreased by 18.5% and 15.1%. The iron plaque formation on rice root surface was enhanced, but its sequestration capacity for Sb decreased due to increasing competition for binding sites led by the elevated phosphorus and silicon levels in pore water after biochar application. The shoot Sb content sharply increased by 215.8% upon straw biochar application.
... Residual fraction of Sb varied from 88.2% to 97.9% because Sb can strongly bind to the aluminosilicate crystal (Flynn et al., 2003;He, 2007). It has been reported that the residual fraction of Sb had a relative content of 47% in contaminated shooting range soil and increased to 55% due to treatment of 2% zero-valent iron (Gudny et al., 2016). Diversified soil physical and chemical properties caused the above differences of speciation distribution. ...
Article
Information on soil antimony (Sb) toxicity to earthworm Eisenia fetida (Savingy) is limited. This ecotoxicology study was designed to quantify the soil Sb toxicity to earthworm E. fetida before and after aging process, establishing dose-effect relationship between Sb content and mortality. Results of the avoidance test and acute test showed that the values of net avoidance response, escape rate and mortality were generally decreased in aged treatment compared to that in fresh treatment, respectively from 93.33% to 66.67%, 36.67% to 13.33% and 100% to 53.33% (15 d) taking TL800 (treatment level of 800 mg/kg) for example, meanwhile the values of median lethal content (LC50) at 72 h, 7 d and 15 d were respectively increased from 355.27 mg/kg to 2324.55 mg/kg, 322.19 mg/kg and 1743.19 mg/kg and 282.74 mg/kg to 745.94 mg/kg, indicating that aging process could reduce the Sb acute toxicity to earthworm. According to a three-step sequential extraction procedure, the bioavailable Sb ranged from 24.45% to 43.24% and 16.97% to 27.70% in fresh treatment and aged treatment, respectively, and the mortality of earthworm for 24 h decreased with the decrease of the content of mild acid-soluble antimony (which decreased averagely from 23.09% to 14.00%), which was more suited to assess Sb toxicity. This is the first report that confirms the toxicity of soil Sb to earthworm E. fetida as well as the considering of aging process and speciation.
... Exposure to antimony could result in various health problems, such as skin, eye, and lung irritation (De Miguel et al. 2017). Leaching of Sb in contaminated lands such as mining areas and disposal sites may pose a serious human and environmental risk (Okkenhaug et al. 2016). Formation of antimoniosis, which is a particular form of pneumoconiosis was reported in the literature as a result of chronic exposure to antimony. ...
Article
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Using association of plants, nanomaterials, and plant growth-promoting bacteria (PGPR) is a novel approach in remediation of heavy metal-contaminated soils. Co-application of nanoscale zerovalent iron (nZVI) and PGPR to promote phytoremediation of Sb-contaminated soil was investigated in this study. Seedlings of Trifolium repens were exposed to different regimes of nZVI (0, 150, 300, 500, and 1000 mg/kg) and the PGPR, separately and in combination, to investigate the effects on plant growth, Sb uptake, and accumulation and physiological response of the plant in contaminated soil. Co-application of nZVI and PGPR had positive effects on plant establishment and growth in contaminated soil. Greater accumulation of Sb in the shoots compared to the roots of T. repens was observed in all treatments. Using nZVI significantly increased accumulation capacity of T. repens for Sb with the greatest accumulation capacity of 3896.4 μg per pot gained in the “PGPR+500 mg/kg nZVI” treatment. Adverse impacts of using 1000 mg/kg nZVI were found on plant growth and phytoremediation performance. Significant beneficial effect of integrated use of nZVI and PGPR on plant photosynthesis was detected. Co-application of nZVI and PGPR could reduce the required amounts of nZVI for successful phytoremediation of metalloid polluted soils. Intelligent uses of plants in accompany with nanomaterials and PGPR have great application prospects in removal of antimony from soil.
... Pb was transformed into residual mineral. [209] Mn oxides Pb immobilization. ...
Article
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Lead (Pb) toxicity has been a subject of interest for environmental scientists due to its toxic effect on plants, animals, and humans. An increase in several Pb related industrial activities and use of Pb containing products such as agrochemicals, oil and paint, mining, etc. can lead to Pb contamination in the environment and thereby, can enter the food chain. Being one of the most toxic heavy metals, Pb ingestion via the food chain has proven to be a potential health hazard for plants and humans. The current review aims to summarize the research updates on Pb toxicity and its effects on plants, soil, and human health. Relevant literature from the past 20 years encompassing comprehensive details on Pb toxicity has been considered with key issues such as i) Pb bioavailability in soil, ii) Pb biomagnification, and iii) Pb-remediation, which has been addressed in detail through physical, chemical, and biological lenses. In the review, among different Pb-remediation approaches, we have highlighted certain advanced approaches such as microbial assisted phytoremediation which could possibly minimize the Pb load from the resources in a sustainable manner and would be a viable option to ensure a safe food production system.
... According to the authors, all the sorbents decrease lead in water and extractable phase significantly (89% and 99% respectively). In addition, remediation remains stable over a 4year experimental period, which indicates that the method is highly efficient (Okkenhaug et al. 2016). ...
Article
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Soil pollution with toxic elements is a recurrent issue due to environmental disasters, fossil fuel burning, urbanization, and industrialization, which have contributed to soil contamination over the years. Therefore, the remediation of toxic metals in soil is always an important topic since contaminated soil can affect the environment, agricultural safety, and human health. Many remediation methods have been developed; however, it is essential to ensure that they are safe, and also take into account the limitation of each methodology (including high energy input and generation of residues). This scenario has motivated this review, where we explore soil contamination with arsenic, lead, mercury, and chromium and summarize information about the methods employed to remediate each of these toxic elements such as phytoremediation, soil washing, electrokinetic remediation, and nanoparticles besides elucidating some mechanisms involved in the remediation. Considering all the discussed techniques, nowadays, different techniques can be combined together in order to improve the efficiency of remediation besides the new approach of the techniques and the use of one technique for remediating more than one contaminant.
... In recent years, Sb concentrations in the environment have considerably increased as a result of mining and smelting operations, waste incinerators, coal and petroleum combustion, spent ammunition, polyethylene terephthalate industries, battery factories, and use of pharmaceuticals and pesticides (e.g. Okkenhaug et al., 2016). In this context, knowledge of Sb mobility, potential bioavailability and bioaccessibility in soil is of primary importance for the assessment of ecological risk and potential human health impacts (Diquattro et al., 2020;Fu et al., 2016;Hammel et al., 2000). ...
Article
The effect of long-term ageing (up to 700 days) on the mobility, potential bioavailability and bioaccessibility of antimony (Sb) was investigated in two soils (S1: pH 8.2; S2: pH 4.9) spiked with two Sb concentrations (100 and 1000 mg·kg⁻¹). The Sb mobility decreased with ageing as highlighted by sequential extraction, while its residual fraction significantly increased. The concentration of Sb (CDGT), as determined by diffusive gradients in thin films (DGT), showed a reduction in potential contaminant bioavailability during ageing. The DGT analysis also showed that Sb-CDGT after 700 days ageing was significantly higher in S1-1000 compared to S2-1000, suggesting soil pH plays a key role in Sb potential bioavailability. In-vitro tests also revealed that Sb bioaccessibility (and Hazard Quotient) decreased over time. Linear combination fitting of Sb K-edge XANES derivative spectra showed, as a general trend, an increase in Sb(V) sorption to inorganic oxides with ageing as well as Sb(V) bound to organic matter (e.g. up to 27 and 37% respectively for S2-100). The results indicated that ageing can alleviate Sb ecotoxicity in soil and that the effectiveness of such processes can be increased at acidic pH. However, substantial risks due to Sb mobility, potential bioavailability and bioaccessibility remained in contaminated soils even after 700 days ageing.
... The proportion of available Pb ranged from 49.3% to 90.9% in different rhizosphere soil, while the carbonated Pb and Fe/Mn oxyhydroxides bounded Pb account for more than 50% (Fig. 2C). Fe/Mn oxyhydroxides has been proven to have a good effect on Pb fixation (Okkenhaug et al., 2016). With soil pH increased (from S3 to S16), the proportion of exchanged Pb was decreased (except for S3) and the proportion of organic bounded Pb was slightly elevated. ...
Article
Lead contamination in soil has become a worldwide threat on food security and human health. To assess the Pb bioavailability and evaluate the safe use of low Pb polluted soil for food production, the speciation of Pb in 19 types of paddy soil were investigated by chemical extraction and X-ray absorption near-edge structure (XANES), and the uptake and accumulation characteristics of Pb in different soil-rice systems were investigated. Moreover, an empirical model was established to predict the content of Pb in rice grain, and field validation was conduct to evaluate model performance. Results showed that the proportion of available Pb in different soil satisfied normal distribution N (0.47, 0.23). Pb(CH3COO)2, GSH-Pb, PbO, PbHPO4 and Pb3(PO4)2 performed well in characterizing the speciation of Pb in different rhizosphere soils, and PbHPO4 accounted for more than 70%. The exceedance of Pb in grain in CK, 0.5X and 1X treatment were 10.5%, 36.1% and 42.1%, respectively, and the accumulation of Pb in grain was significantly related with Pb content in root. Carbonate and organic bound Pb in rhizosphere soil were two major Pb species that influenced the accumulation of Pb in rice. Moreover, content of total Pb, clay and SOM performed well in predicting the Pb content in grain, both for pot and field samples. Above all, our predicting model worked well in evaluating Pb accumulation in rice grain among low polluted paddy farmland (Total Pb < 300 mg/kg).
... [22] Successful immobilization of some heavy metals in soil by Fe-based amendments such as zerovalent iron grit (Fe ) has been reported in the literature. [23][24][25] Using of Fe0 and Fe3O4 nanoparticles for stabilizing aqueous APG-Ph foam and potential of these stabilized foams to remediate different type of soil was included diesel-contaminated desert soil, coastal soil, and clay soil were successful. [25] In another study, Cd uptake by soybean increased from 128.5 to 507.6 mg per plant as a result of addition of 100 to 300 mg/kg TiO 2 NPs to soil. ...
Article
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Soil is a major sink for heavy metals released into the environment. The remediation of Pb-polluted soils brings a techno-economical challenge for researchers and decision makers. Phytoremediation enhanced by PGPR or nanomaterials, individually, have been studied to remove contaminants such as heavy metals from soil, but association of both PGPR and nanomaterials in phytoremediation of Pb contaminated soil has remained scant.Association of plants, nanomaterials and plant growth promoting bacteria (PGPR) was investigated for the first time in this research to support remediation of Pb, while optimizing the quantity of used nanomaterials. Seedlings of S. bicolor were exposed to different regimes of TiO2 NPs (0, 100, 250, 500 and 1000 mg/kg) and the PGPR, separately and in combination, to investigate the effects on plant growth, Pb uptake and accumulation and physiological response of the plant in contaminated soil. Greater accumulation of Pb in the roots compared to the shoots of S. bicolor was observed in all treatments. Application of PGPR enhanced Pb uptake by roots. Using TiO2 NPs significantly increased accumulation capacity of S. bicolor for Pb with the greatest accumulation capacity of 1377.18 µg per pot achieved in the “PGPR + 500 mg/kg TiO2 NPs” treatment (p < 0.05). Adverse effects of using high concentration of TiO2 NPs i.e., 1000 mg/kg were found on plant growth and phytoremediation performance. Significant beneficial effect of integrated use of TiO2 NPs and PGPR on plant photosynthesis was also found. Promoted physiological response like relative growth and production of chlorophyll content was found for plants treated with association of TiO2 NPs and the PGPR. Co-application of TiO2 NPs and PGPR could reduce the required amounts of TiO2 NPs for successful phytoremediation of heavy metalloid polluted soils. Results of this study presented a promising novel technique by combined application of TiO2 NPs and PGPR in phytoremediation of Pb contaminated soils. Intelligent uses of plants in accompany with nanomaterials and PGPR have great application prospects in dealing with soil remediation.
... Antimony has a wide range of applications in industry such as manufacturing of semiconductors, medicine, fire retardants, lead hardeners, diodes, cable coverings, alloys, batteries, polyethylene terephthalate (PET), brake linings and pigments (Bagherifam et al., 2019;Pan et al., 2011). Leaching of Sb in contaminated lands such as mining areas and disposal sites may pose a serious human and environmental risk (Okkenhaug et al., 2016). Formation of antimoniosis, which is a particular form of pneumoconiosis, was reported in the literature as a result of chronic exposure to antimony. ...
Article
Full-text available
Association of titanium dioxide nanoparticles (TiO2 NPs) and biochar (BC) to assist phytoremediation of Sb contaminated soil was investigated in this study. Seedlings of Sorghum bicolor were exposed to different regimes of TiO2 NPs (0, 100, 250 and 500 mg kg⁻¹) and BC (0, 2.5% and 5%), separately and in combination, to investigate the effects on plant growth, Sb absorption and accumulation and physiological response of the plant in Sb contaminated soil. Co-application of TiO2 NPs and BC had positive effects on plant establishment and growth in contaminated soil. Greater accumulation of Sb in the shoots compared to the roots of S. bicolor was observed in all treatments. Application of BC increased immobilization of Sb in the soil. Using TiO2 NPs significantly increased accumulation capacity of S. bicolor for Sb with the greatest accumulation capacity of 1624.1 μg per pot achieved in “250 mg kg⁻¹ TiO2 NPs+2.5% BC” treatment (P < 0.05). Association of TiO2 NPs and BC significantly increased chlorophyll a (Chl a) and chlorophyll b (Chl b) contents of S. bicolor compared to the TiO2 NPs-amended treatments. Results of this study presented a promising novel technique by combined application of TiO2 NPs and BC in phytoremediation of Sb contaminated soils. Co-application of TiO2 NPs and BC could reduce the required amounts of TiO2 NPs for successful phytoremediation of heavy metal polluted soils. Intelligent uses of plants in accompany with biochar and nanomaterials have great application prospects in dealing with soil remediation.
... It is the ninth most mined element in the world [8], and it also occurs in nature as Sb 2 O 3. As a very toxic metal, Sb can be widely found in soil and aquatic systems (mainly fresh and marine water) in the form of stibnite (Sb 2 S 3 ). Soil enriched with antimony is a direct manifestation caused by the mobilization of antimony from mineral ores, discarded mines and other activities such as mining, mineral smelting along with drugs and pesticides production [9,10]. Diantimony trioxide Sb 2 O 3 is used as a catalyst in the production of polyethylene terephthalate (PET) and as a flame retardant in the production of plastics, textiles and rubber [11]. ...
... The presence of organic matter leads to the accumulation of Pb, but increment of Pb concentrations due to weathering of bullets causes that organic Pb complexes became unstable, being Pb easily leached out (Hartikainen & Kerko, 2009). However, Fe and Mn oxides play the opposite role in shooting range soils, acting as stabilization agents, immobilizing and restrict migration, leaching and bioavailability of Pb (Okkenhaug et al., 2016;Sanderson et al., 2018;Tandy et al., 2017). Besides, Arenas-Lago et al. (2014) indicated that there is a relationship between the Fe and Mn oxide contents in the soil and Pb content associated with these components. ...
Article
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Civilian and military shooting range facilities cause environmental issues in several countries due to the accumulation of Potentially Toxic Elements; as a result of weathering of ammunitions accumulated into the soils. The contents and distribution of Cu, Ni, Pb and Zn were analyzed in 12 soils in an abandoned clay target shooting range at two different depths (0–15 and 15–30 cm). Single extractions (CaCl2 and DTPA) and Tessier sequential extraction were conducted to assess the PTE mobility and the PTE distribution in the different soil geochemical fractions at both depths. High total contents of Pb were found at both soil depths, while Cu, Ni and Zn showed lower significance levels. Copper, Ni and Zn are mainly associated with the residual fraction (> 95% of total content in all cases). However, Pb was highly associated with exchangeable fractions (21–52%), showing a high mobility at both depths. With moderate-high contents of organic matter (6–12%), the studied soils have acidic values and low levels of Al, Fe and Mn oxides that favors the migration of Pb through the soil profile and potential transformation to more mobile forms (Pb0 to Pb2+ and Pb4+). Although Pb reduced downward mobility in soils, due to the specific conditions of these facilities and the lead source (weathering of ammunition), risk assessment studies on clay-target shooting and firing range facilities should study the potential migration of Pb through the soil profile.
... Sb, a toxic metalloid, has attracted wide attention from researchers owing to the excessive exploitation and smelting of Sb ores in mine. When Sb is mined and smelted, it is transferred into organisms through the food chain, which causes chronic toxic effects on human immunity, nervous system, heart, and liver (Gebel, 1997;Cavallo et al., 2002;Okkenhaug et al., 2016). The Sb(III), Sb(V) and organic valence states of Sb are the most common forms, and environmental toxicity of Sb is determined by its valence states (Filella et al., 2002). ...
Article
In this study, the preparation conditions of nano zero-valent iron biochar (nZVI -BC) was optimised with the aim of removing Sb(III) from aqueous solutions. Among all the prepared nZVI-BC, 5-1nZVI-BC (98.25 mg/g) and 7-4nZVI-BC (91.26 mg/g) were considered to be more efficient adsorbents for Sb(III) adsorption, and their adsorption capacity increased by 457% and 157%, respectively, than that of pristine BC. Both the Langmuir and Freundlich models were well fitted (R² ≥ 0.92), indicating that the adsorption process occurred through the synergistic effects of monolayer adsorption and multilayer adsorption. With the increase in the ratio of biochar to iron, the second-order kinetics could better describe the adsorption behaviour, which was controlled by chemisorption. Investigation of the adsorption mechanism using X-ray photoelectron spectroscopy (XPS) and kinetic modelling showed that there were two adsorption behaviours for Sb(III): (i) Sb(V) from the oxidisation of Sb(III) or Sb(III) combined with the functional groups on the surface of nZVI-BC to form antimonite/antimonate, which was attached to biochar surface to remove Sb(III). (ii) Negatively charged Sb(III)/Sb(V) combined with Fe(II)/Fe(III) to form precipitates, such as FeSb 2O4 and FeSbO 4, that were attached to the biochar surface, resulting in removing of Sb(III). Moreover, the reusability and recyclability of the screened nZVI-BC samples were tested in this study. The removal rate for Sb(III) remained approximately 75% after three reuses and 50%–80% through adsorption/desorption after two cycles. These results show that the screened nZVI-BC has a promising prospect as an economical and efficient adsorbent for Sb(III) removal from wastewater.
... Iron-based amendments have been reported to have high selectivity for Sb (Mariussen et al., 2015;Okkenhaug et al., 2013Okkenhaug et al., , 2016Silvani et al., 2019). Antimony retention was found to be irreversible in ferrosols indicating the affinity of Sb to form stable complex with Fe-(hydro)oxides. ...
Article
(Share link--------------------------------------->) https://authors.elsevier.com/c/1fW2kMUQfZV84 Antimony (Sb) is a non-essential element for plants, animals, and humans. With increased anthropogenic inputs from mining and industrial activities, ore processing, vehicle emissions, and shooting activities, elevated Sb levels in the environment have become a growing concern. Despite of its non-essentiality, some plants can take up and accumulate Sb in relatively high concentrations in their organs. At increased concentration in edible plant parts or medicinal herbs it may pose health risks to humans and livestock. Although most of Sb is stored in root tissues, a smaller quantity of this metalloid can be translocated to the shoot depending on the plant species, where it exerts a variety of deleterious effects. Its chemical speciation has an influence on its behavior in the environment and its ecotoxicity. Inhibition of photosynthesis, modified root and leaf anatomy, activation of plant antioxidant system, or disruption of plant membrane system are some of the negative effects of Sb on plant growth and development. Studies on mitigation methods are quite important in order to produce food crops in a safe way. Application of silicon, selenium, biochar, nanoparticles, and microoraginsms are proven to be emerging strategies for reducing the Sb toxicity.
... In nature, the most common species of Sb are the neutral Sb(III) (Sb(OH) 3 ) and the anionic Sb(V) (Sb(OH) 6− ). 16 Sb (V) has been found to be the most stable and abundant species and much more soluble than Sb (III). 12 Sb (V) poses a greater pollution risk to the environment than Sb (III) due to its high solubility even at pH close to neutral. ...
Article
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Soil samples collected from the berm at Thebephatshwa (TAB) shooting range found in Botswana showed variable total concentrations of antimony in the range 38±1 to 283±12 mg/kg. Total antimony concentrations found in the soils were higher than the set regulatory levels by the World Health Organization (36 mg/kg) and the United States Protection Agency (31 mg/kg). The upper berm showed elevated levels of antimony (283±12 mg/kg) due, in part, to the highest density of spent projectiles found in this part of the berm. Sequential extraction studies established that antimony was partitioned mostly in the organic and residual fractions of the soil. Environmental pollution risk assessment based on geoaccumulation index (I geo), contamination factor (CF) and enrichment factor (EF) indicated all four sections of the berm posed high risk to the environment. The upper berm exhibited extreme pollution from antimony (I geo ~9), very high contamination (CF ~744) and extreme antimony enrichment (EF ~506) compared to the other three sections studied. Elevated levels of antimony at TAB shooting range call for best shooting range management practices, soil remediation and reclamation methods to be carried out at this shooting range to minimize the mobility and bioavailability of antimony.
... Sb, a toxic metalloid, has attracted wide attention from researchers owing to the excessive exploitation and smelting of Sb ores in mine. When Sb is mined and smelted, it is transferred into organisms through the food chain, which causes chronic toxic effects on human immunity, nervous system, heart, and liver (Gebel, 1997;Cavallo et al., 2002;Okkenhaug et al., 2016). The Sb(III), Sb(V) and organic valence states of Sb are the most common forms, and environmental toxicity of Sb is determined by its valence states (Filella et al., 2002). ...
Article
As rapid industrial and social growth, antimony mines are the overexploited, leading to the accumulation of trivalent antimony in the aquatic environment near smelters, which harm human health. To eradicate trivalent antimony from water, an innovative nanomaterial in the form of sludge biochar loaded with zero-valent bimetal was synthesized using a liquid-phase reduction method. The adsorption performance of the nanomaterial for trivalent antimony was investigated based on a series of adsorption experiments using sludge biochar, nano zero-valent iron biochar, and nano zero-valent bimetal biochar. The results showed that the optimal adsorption performance of the three nanomaterials for trivalent antimony, considering the economic practicability, was highlighted at solution pH of 3 and 0.05 g of nanomaterial. Additionally, the maximum adsorption capacity of sludge biochar, nano zero-valent iron biochar, and nano zero-valent bimetal biochar is 3.89 mg g⁻¹ at 35 °C, 32.01 mg g⁻¹ at 25 °C, 50.96 mg g⁻¹ at 25 °C, respectively. The adsorption process of sludge biochar is endothermic, resulting in an increase in the adsorption capacity with increasing temperature, whereas the exothermic reaction contributes to decrease in the adsorption capacity at increasing temperature for the other two carbon nanomaterials. The inhibitory effect of coexisting ions was in the order: Al³⁺ > NH4⁺ > Na⁺ > K⁺; CO3²⁻ > CH3COO⁻ > H2PO4⁻ > S²⁻. Additionally, nanomaterials promoted seed germination and growth. Investigation of the adsorption mechanism using X-ray photoelectron spectroscopy showed that trivalent antimony was oxidised to pentavalent antimony, and Fe(III) was reduced to Fe(II). The formed primary battery formed by copper ions and iron acclerated electron transfer and improved the adsorption rate. This implied that trivalent antimony could be removed through the synergistic action of the adsorption behaviour and redox reaction. Therefore, the biochar loaded with the zero-valent bimetal serves as a pathway for eradicating trivalent antimony.
... Fe minerals have been extensively studied as ideal Sb adsorbents due to their strong affinity for environmentally relevant Sb species; examples of the adsorbents include goethite, hydrous ferric oxide, akageneite, and nano Fe 3 O 4 coated Fe oxy-hydroxides Guo et al., 2014;Kolbe et al., 2011;Simeonidis et al., 2019). A field study has also demonstrated efficient removal of Sb from shooting ranges using Fe adsorbents (Okkenhaug et al., 2016). Other examples of promising mineral-based adsorbent of Sb include Mn minerals such as hydrotalcite and biogenic manganese oxide, and Fe-Mg layered double hydroxide (LDH) with interlayered hydroxyl (Cao et al., 2020;Constantino et al., 2018;Wang et al., 2019). ...
Article
The environmental behavior of antimony (Sb) has recently received greater attention due to the increasing global use of Sb in a range of industrial applications. Although present at trace levels in most natural systems, elevated Sb concentrations in aquatic and terrestrial environments may result from anthropogenic activities. The mobility and toxicity of Sb largely depend on its speciation, which is dependent to a large extent on its oxidation state. To a certain extent, our understanding of the environmental behavior of Sb has been informed by studies of the environmental behavior of arsenic (As) as Sb and As have somewhat similar chemical properties. However, recently it has become evident that the speciation of Sb and As, especially in the context of redox reactions, may be fundamentally different. Therefore, it is crucial to study the biogeochemical processes impacting Sb redox transformations to understand the behavior of Sb in natural and engineered environments. Currently, there is a growing body of literature involving the speciation, mobility, toxicity, and remediation of Sb, and several reviews on these general topics are available; however, a comprehensive review focused on Sb environmental redox chemistry is lacking. This paper provides a review of research conducted within the past two decades examining the redox chemistry of Sb in aquatic and terrestrial environments and identifies knowledge gaps that need to be addressed to develop a better understanding of Sb biogeochemistry for improved management of Sb in natural and engineered systems.
... Elevated levels of antimony (Sb) in soils, sediments, water and biological systems have drawn considerable attention worldwide due to its adverse effects on human health ( Fort et al., 2016 ;Okkenhaug et al., 2016 ). Antimony is highly attracted ter recommended by the United States Environmental Protection Agency (USEPA) and World Health Organization (WHO) is 6 and 10 μg/L, respectively. ...
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Soils and waters are heavily contaminated by antimony in Xikuangshan (XKS) mine area. It is widely accepted that oxidative dissolution of sulfide minerals and aqueous dissolution are the most prevalent geochemical mechanisms for the release of Sb to the environment. Bosea sp. AS-1 is an antimonite-oxidizer isolated from the mine slag in Xikuangshan Sb mine. Whole genome sequencing revealed the presence of multiple sulfur-oxidizing genes, antimony (Sb) metabolism genes and carbon fixation genes in AS-1′s genome. We therefore hypothesized that under oxic conditions, AS-1 could mediate the oxidation of sulfide and Sb(III) in stibnite (Sb2S3) and lead to the release of Sb. Indeed, strain AS-1 was discovered as an autotrophic Sb(III)-oxidizer. Antimony mobilization studies conducted with strain AS-1 showed significantly enhanced mobilization of Sb, and complete oxidation of released Sb and sulfur to Sb(V) and sulfate. In addition, AS-1 induced a faster release of Sb under heterotrophic condition, and new acicular minerals might form. These findings support the hypothesis that microorganisms play an important role in the mobilization and transformation of Sb in XKS mine area and may contribute to our further understanding of the Sb biogeochemical redox cycle in natural environment.
... The processes of lead shot transformation under the atmospheric and soil corrosion factors are well-known (SAAMI, 1996;Lin, 1996;Rooney et al., 1999;Cao et al., 2003;Dermatas et al., 2006;Rauckyte et al., 2009;Lewis et al., 2011;Mera et al., 2015;Okkenhaug et al., 2016;Kelebemang et al., 2017;Lisin et al., 2020). Some studies (Schwarz et al., 2015;Fäth et al., 2018;Fäth and Göttlein, 2019) analyzed the potential risks for aquatic ecosystems in case of the steel ammunition presence. ...
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This paper presents the results of an experimental study of the patterns of steel and lead shot transformation under the impact of environmental factors (two types of shot exposed alone and in combination with each other). The analyzed environmental factors include atmospheric precipitation of various acidity and soil solutions with a higher content of organic acids. This research demonstrated that steel shot is characterized by a high transformation rate that is an order of magnitude higher on average than the transformation rate of lead under the same conditions. The prevalence of the suspended iron form (excluding the interaction with organic acids) presents risks for such environmental components as soils and sediments and may be hazardous to the ambient air and natural waters in case of wind erosion and surface runoff from the catchment area. Furthermore, the joint presence of steel and lead shot mutually accelerates the corrosion of both metals, thus increasing the environmental risks.
... The intended alteration of metal (Pb) bioavailability by the addition of chemical amendments represents an effective means of mitigating environmental risks without the high costs usually associated with unsustainable traditional remediation strategies [28]. Contaminated shooting range soils have been mainly treated with a variety of inorganic amendments (Table 1), which can be either synthetic or mined materials, such as phosphates [36][37][38][39][40][41][42], lime-based compounds [43,44], and metal oxides [24,37,45], in order to induce specific reactions within the soil components to render Pb inert without substantially affecting soil properties [28]. The chemical reactions involved in Pb immobilization by the abovementioned amendments are summarized in Table 2. [13,37,38,50,51]. ...
Article
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Soil metal contamination in recreational shooting ranges represents a widespread environmental problem. Lead (Pb) is the primary component of traditional ammunition, followed by metalloids such as antimony (Sb) and arsenic (As). Lead-based bullets and pellets deposited on the soil surface are subject to steady weathering; hence, metal(loid)s are released and accumulated in the underlying soil, with potential adverse consequences for ecosystem function and human health. Amongst the currently available environmentally-safe technologies for the remediation of metal-contaminated soils, chemical immobilization is recognized as the most practical and cost-effective one. This technology often uses inorganic and organic amendments to reduce metal mobility, bioavailability and toxicity (environmental benefits). Likewise, amendments may also promote and speed up the re-establishment of vegetation on metal-affected soils, thus facilitating the conversion of abandoned shooting ranges into public green spaces (social benefit). In line with this, the circular economy paradigm calls for a more sustainable waste management, for instance, by recycling and reusing by-products and wastes in an attempt to reduce the demand for raw materials (economic benefit). The objective of this manuscript is to present a state-of-the-art review of the different industrial and agro-food by-products and wastes used for the remediation of metal-contaminated shooting range soils.
... Pb was transformed into residual mineral. [209] Mn oxides Pb immobilization. ...
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MEDICAL GEOLOGY
... Arsenic and other oxyanions were the most common contaminants targeted by Fe-based amendments (Komárek et al. 2013). Iron oxides have shown high sorption capacities for cationic elements of Cd, Pb, and Zn, due to their amphoteric nature (Nielsen et al. 2016;Okkenhaug et al. 2016). Aluminum-and Ti-oxide nanoparticles can be present in many natural systems and can play a significant role in binding of heavy metals to surfaces, or by changing into more stable mineral forms, as effectively as or may be even better than Fe nano-oxides. ...
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Nanoparticles with high reactivity can be applied as amendments to remediate soil metal contaminations by immobilizing toxic elements. Nano-oxides of Fe have been studied but Al and Ti nano-oxides have not been tested for their remediation capacity of toxic metals. The potential of synthesized iron (Fe-O), aluminum (Al-O), and titanium (Ti-O) nano-oxides for stabilizing Cd, Pb, and Zn in mine spoil (Chat) and contaminated soil was compared using adsorption studies and a greenhouse experiment. Chat and soil were amended with nano-oxides at two rates (25 and 50 g·kg ⁻¹ ) and a pot experiment was conducted with sorghum (Sorghum bicolor L. Moench). Leachates were collected twice per week from plant emergence to harvest at maturity and metals were compared against an unamended control. Chat was contaminated with Cd, Pb, and Zn at 84, 1583, and 6154 mg·kg ⁻¹ , and soil at 15, 1260, and 3082 mg·kg ⁻¹ , respectively. Adsorption conformed to the Langmuir linear isotherm and adsorption maxima of metals were in the order of Al-O > Ti-O ≥ Fe-O. Nano-oxides reduced Cd concentration by 28% (Fe-O) to 87% (Ti-O) and Zn concentration by 14% (Fe-O) to 85% (Al-O) in plant tissues compared with unamended Chat. Nano-oxides significantly reduced Cd, Pb, and Zn in leachates and available Cd and Zn in Chat/soil relative to the respective unamended controls. Nano-oxides can be used to remediate heavy metal contaminated Chat and soil and facilitate plant growth under proper nutrient supplements. Nano-oxides of Al-O and Ti-O remediated metals more effectively than Fe-O.
Article
The rapid progression of piezoelectric technology and the upgradation of electronic devices have resulted in a global increase in Pb-based piezoelectric ceramic materials. In this study, the feasibility of incorporating Pb into a PbZr(PO4)2 double orthophosphate structure was evaluated by investigating the interaction mechanism of the perovskite with phosphate. The unique combination of X-ray absorption spectroscopy, selected area electronic diffraction, and Pawley refinement revealed that Pb was incorporated into a hexagonal structure and tetra-coordinated with oxygen in the phosphate-treated product. The chemical durability was enhanced through the structural alterations via Zr-O-P and Pb-O-P bond linkages. The stable phase encapsulating both Pb and phosphate showed effectiveness not only in stabilizing Pb but also in inhibiting P release as a secondary pollution risk within a wide pH range (1 ≤ pH ≤ 13). Despite the excellent chemical durability of the robust PbZr(PO4)2 crystalline phase, the increased Ti doping amounts at the Zr site resulted in a slight decrease in the lattice parameters and further enhanced the Pb stabilization effect through the formation of PbZr x Ti(1-x)(PO4)2 solid solutions. This study demonstrates that the newly robust crystalline structure, developed through a well-designed thermal treatment scheme, provides an effective strategy for the treatment of Pb frequently encountered in electronic wastes.
Article
In this study, the feasibility of using zero-valent iron (ZVI) and Fe3O4-loaded biochar for Pb immobilization in contaminated sandy soil was investigated. A 180-day incubation study, combined with dry magnetic separation, chemical extraction, mineralogical characterization, and model plant (ryegrass, namely the Lilium perenne L.) growth experiment was conducted to verify the performance of these two materials. The results showed that both amendments significantly transferred the available Pb (the exchangeable and carbonates fraction) into more stable fractions (mainly Fe/Mn oxides-bound Pb), and ZVI alone showed a better performance than the magnetic biochar alone. The magnetic separation and extended X-ray absorption fine structure (EXAFS) analysis proved that Fe (oxyhydr)oxides on aged ZVI particles were the major scavengers of Pb in ZVI-amended soils. In comparison, the reduced Pb availability in magnetic biochar-amended soil could be explained by the association of Pb with Fe/Mn (oxyhydr)oxides in aged magnetic biochar, also the possible precipitation of soil Pb with soluble anions (e.g. OH⁻, PO4³⁻, and SO4²⁻) released from magnetic biochar. ZVI increased ryegrass production while Fe3O4-loaded biochar had a negative effect on the ryegrass growth. Moreover, both markedly decreased the Pb accumulation in aboveground and root tissues. The simple dry magnetic separation presents opportunities for the removal of Pb from soils, even though the efficiencies were not high (17.5% and 12.9% of total Pb from ZVI and biochar-treated soils, respectively). However, it should be noted that the ageing process easily result in the loss of magnetism of ZVI while the magnetic biochar tends to be more stable and has high retrievability during the dry magnetic separation application.
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In this study, a novel method for lead (Pb) immobilization was developed in contaminated soils using iron (III) (Fe³⁺) in conjunction with 0.05 M H2SO4. During method optimization, a range of microwave treatment times, solid to solution ratios, and Fe2(SO4)3/H2SO4 concentrations were assessed using a mining/smelting impacted soil (BHK2, Pb: 3031 mg/kg), followed by treatment of additional Pb contaminated soils (PP, Pb: 1506 mg/kg, G10, Pb: 2454 mg/kg and SoFC-1, Pb: 6340 mg/kg) using the optimized method. Pb bioaccessibility was assessed using USEPA Method 1340, with Pb speciation determined by X-ray Absorption (XAS) spectroscopy. Treatment efficacy was also validated using an in vivo mouse assay, where Pb accumulation in femur, kidney and liver was assessed to confirm in vitro bioaccessibility outcomes. Results showed that Pb bioaccessibility could be reduced by 77.4 - 97.0% following treatment of soil with Fe2(SO4)3 (0.4 - 1.0 M), H2SO4 (0.05 M) at 150°C for 60 min in a closed microwave system. Results of bioavailability assessment demonstrated treatment effect ratio of 0.06 - 0.07 in femur, 0.06 - 0.27 in kidney and 0.06 - 0.11 in liver (bioavailability reduction between 73-93%). Formation of plumbojarosite in treated soils was confirmed by XAS analysis.
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Heavy metals are prevalent in the environment and can cause disease in humans via the soil-plant-food chain. However, singular soil remediation techniques, such as pristine biochar, are susceptible to instabilities and low efficiency. Here, biochar-mineral (kaolin/vermiculite/attapulgite) composites were fabricated and characterized. A pot culture was carried out to certify the efficacy of the biochar-mineral composites to immobilize naturally heavy metals contaminated soils and reduce the bioavailability of heavy metals to plants. The results confirmed that biochar-mineral composites significantly impact the available K, available P, total N, and organic matter content of soil, which improved Brassica chinensis growth. Furthermore, the heavy metals’ phytoavailability in naturally polluted soil and the accumulation in B. chinensis were reduced significantly. Biochar-attapulgite composite addition, especially at the 2% application rate, significantly enhanced heavy metal immobilization and had the highest efficacy. These findings demonstrated that biochar-mineral composites could be applied in naturally contaminated soil as effective and eco-friendly heavy metals passivators.
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Lead (Pb) toxicity has been a subject of interest for environmental scientists due to its toxic effect on plants, animals, and humans. An increase in several Pb related industrial activities and use of Pb containing products such as agrochemicals, oil and paint, mining, etc. can lead to Pb contamination in the environment and thereby, can enter the food chain. Being one of the most toxic heavy metals, Pb ingestion via the food chain has proven to be a potential health hazard for plants and humans. The current review aims to summarize the research updates on Pb toxicity and its effects on plants, soil, and human health. Relevant literature from the past 20 years encompassing comprehensive details on Pb toxicity has been considered with key issues such as i) Pb bioavailability in soil, ii) Pb biomagnification, and iii) Pb-remediation, which has been addressed in detail through physical, chemical, and biological lenses. In the review, among different Pb-remediation approaches, we have highlighted certain advanced approaches such as microbial assisted phytoremediation which could possibly minimize the Pb load from the resources in a sustainable manner and would be a viable option to ensure a safe food production system.
Article
Currently, metalloid co-contamination, such as antimony and arsenic in soil, poses a serious threat to ecological stability and human health. Stabilization, a low-cost, effective, environmentally mild remediation strategy, shows enormous potential for mitigating environmental concerns. In this study, a novel FeMg modified porous biochar with different Fe/Mg proportions was prepared using the co-precipitation method to investigate the stabilizing efficiency in aqueous solutions and real soils. The optimal removal performance for Sb(V) and As(V) was the 1/3 mol ratio of Fe/Mg (3FMKBC), in which the maximum adsorption capacities of Sb(V) and As(V) were 296.9 and 195.4 mg/g, respectively. Detailed morphological and BET analyses suggested that BC effectively reduced Fe and Mg oxide agglomeration and endowed more interfacial active sites. Meanwhile, detailed adsorption behavior and surface analysis of 3FMKBC indicated that electrostatic interactions, hydrogen bonds, surface hydroxyl complexation, and ligand exchange induced by ≡C-O-Fe/Mg-OH dominated the stabilization process. Moreover, according to a 40-day incubation study in soil, 3FMKBC (1 wt. ml) decreased the available Sb (28.5% and 23.0%) and As (83.1% and 31.1%) extracted by toxicity characteristic leaching procedure (TCLP) and 0.1 M Na2HPO4, respectively. The above results indicated that 3FMKBC was an optimal amendment for limiting the migration and bioavailability of Sb and As. In addition, the sequential extraction and soil properties confirmed that 3FMKBC could realize the redistribution of resolved Sb and As between the soil solution and solid particles effectively, thereby converting the bioavailable/labile fraction of Sb and As to a more stabilized fraction. All results demonstrated that 3FMKBC could be a prospective material for Sb and As co-contamination stabilization.
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Cationic and anionic heavy metal contamination sometimes co-exists in soil systems, such as mining areas and shooting ranges, seriously threatens human health and ecological stability. In this study, iron-modified rice husk hydrochar showed commendable ability to immobilize both heavy metal cation (Pb) and anion (Sb) simultaneously in soils. Iron-modified rice husk hydrochar (HC12.5–180) (5%) amendment reduced the bioavailability (EX– and CB–fraction) of Pb and Sb by 25 and 40%, respectively, which were 8 and 5 times higher than that of pristine rice husk hydrochar (HC0–180) (5%) amendment. The cation (Pb) immobilization mainly depends on cation exchange with mineral components (K⁺, Ca²⁺, Na⁺, Mg²⁺), precipitation with nonmetallic anions (Cl- and SO4²⁻), and complexation. Meanwhile, the iron oxides (FeO, Fe2O3, Fe3O4), formed during hydrothermal process, can be easily combined with anion (Sb) to form geochemically stable minerals. In conclusion, this work offered a practical and cost-effective technology based on the iron modification rice husk hydrochar for the immobilization of both anionic and cationic heavy metal contaminants in soils.
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This study presents a systematic on-site remediation case involving both heavy metal and organic contaminants in soil and groundwater in a historically industrial-used site in Shanghai, China. Lab-scale experiments and field tests were conducted to determine the optimum parameters for the removal of contaminants in soil and groundwater. It has been found that the remediation goal of hexavalent chromium in soil could be achieved with the mass content of added sodium hydrosulfite and ferrous sulfate reaching 3% + 6%. The total chromium in the groundwater was effectively removed, when the mass ratio of sodium metabisulfite was not less than 3 g/L, and the added quick lime made pH value not less than 9. The concentrations of arsenic and 1,2-dichloropropane in the groundwater decreased evidently after extraction and mixing of groundwater. The pH and calcium chloride dosage added should be larger than 9.5 and 5 g/L, respectively, to remove phosphate in groundwater. The removal efficiency of those contaminants was examined and evaluated after the on-site remediation. The results demonstrated that it was feasible to use the chemical reduction and solidification/stabilization methods for the on-site ex situ remediation of this site, which could be referenced for the realistic remediation of similar sites.
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Lead (Pb) and antimony (Sb) associated with bullets pose a long term contamination risk in shooting ranges because bullet fragments weather over years to decades. In this study we analyzed bullet and soil samples from a historic military shooting range in interior Alaska. Bulk speciation analysis coupled with micro-scale analytical methods demonstrate the presence of Sb(V) in octahedral coordination with 5.3(1) O and a second shell of 3(1) Fe atoms is the primary species present in the weathered bullet crust. However, trivalent Sb bound to 3.1(2) O atoms is likely the initial oxidation species as detected at the soil/alloy interface of a weathered bullet from this study. Similar analysis shows that cerussite (PbCO3), hydrocerussite (Pb3(CO3)2(OH)2), and litharge (PbO) comprise the majority of the Pb species in the weathering crust but Pb(II) adsorbed to Fe(III) oxides are also present in the soil distal to the source material. These results show differences in speciation between the weathering crust and soil fraction in shooting range samples and highlight the natural association of Pb and Sb with Fe. Understanding metal speciation is a critical first step in developing and implementing remediation strategies in small arms shooting ranges.
Article
Antimony (Sb) is a naturally occurring element; it is enriched in the environment by anthropogenic activities. Like other metalloid species, Sb partitions to mineral phases such as oxyhydroxides. In reducing environments, Fe(III) may serve as a terminal electron acceptor during dissimilatory iron reduction leading to its transformation. Relatively little is known concerning the effect of Sb(V) on the precipitation of biogenic minerals in relation to microbiologically mediated redox reactions. To further our understanding, Sb-bearing ferrihydrites (0.5 g) with variable Sb/(Fe + Sb) molar ratios of 0.04, 0.06 and 0.1, were incubated in the presence of Shewanella oneindensis MR-1 (1 x 10⁸ cell mL⁻¹) under N2 atmosphere. Additionally, we synthesized abiotic GR1(CO3²⁻) in the presence of Sb(V) to examine the effect of Sb(V) on this mineral formation and stabilization. A combination of wet chemistry and solid analysis techniques (XRD, Mössbauer and Raman spectroscopies) was used to characterize the reactions. The Sb loading affected the rate and the extent of bio-reduction compared with pure ferrihydrite. Only a minor fraction of the total Sb, less than 0.5 %, was released into the solution by the end of the incubation period, suggesting that the metalloid partitioned mainly in a newly formed phase. Furthermore, XPS analyses showed the presence of Sb(V) and Sb(III) species on the biogenic minerals. Magnetite was the main biogenic precipitate (91 %) in the absence of Sb(V). Increasing of the molar ratios [Sb/(Fe + Sb)] to 0.1 resulted mainly in the precipitation of carbonated green (47 %) rust and goethite (37 %). Abiotic green rust synthesis carried out in the presence of Sb(V) indicated the latter’s stabilizing effect on the green rust structure, as for phosphate species. Thus, it is likely that Sb(V) preserve biogenic green rust, hindering its transformation to more thermodynamically stable phases.
Article
This study investigated the long-term leachability of antimony (Sb) in a smelting residue (39519 mg/kg) solidified/stabilized by reactive magnesia (MgO). Different dosages of MgO (0% as control, 2%, 5%, and 10% on a dry basis) were compared, and the long-term performance was evaluated by an accelerated exposure test consist of 20 consecutive leaching steps with simulated strong acid rain (SAR, HNO3: H2SO4 = 1:2, pH = 3.20) as the extractant. Notably, the MgO treatments efficiently reduced the Sb leachability. Compared to the original slag (8.3 mg/L), the leaching concentrations based on a Chinese standard HJ/T299-2007 were reduced by 58%, 79%, 85%, and 86% at MgO dosages of 0%, 2%, 5%, and 10%, respectively. Because the studied slag was rich in oxides like SiO2, CaO, and MgO, the hydration reactions probably happened during the aging processes with oxic water. It was inferred that the formed hydration products have a self-solidification/stabilization function to suppress the Sb leaching from the solid phase. The mineralogical characterization results proved that the hydrated Mg(OH)2 played an essential role in the decrease of Sb leachability. Besides, the MgO addition promoted the hydration of this smelting slag and formed new hydrate gels that immobilize Sb in this slag. Our results confirmed that MgO-amended slags were resistant to continuous SAR corrosion. Compared to the control, the dosage of 5% MgO could effectively reduce the cumulatively released Sb by 57%, with only 0.46% of total Sb could be leached. The decomposition of Mg(OH)2 and hydrate gels determined the re-release of Sb in a long term. Our work has demonstrated that reactive MgO amendment could be potentially selected as an effective strategy for the treatment of Sb-containing smelting residues in field conditions.
Article
Antimony (Sb), a toxic metalloid element, is located in the Group VA of the fifth period of the periodic table of elements. At present, with the wide use of antimony containing products in the world and the corresponding mining activities, a large number of antimony containing waste generated in these processes has also been released to the environment, resulting in antimony pollution has become a problem that cannot be ignored. People exposed to high concentrations of antimony will produce a series of health risks, which may lead to vomiting, diarrhea, rash and other diseases, and even cancer. Antimony in the environment comes from natural processes (ore weathering, volcanic activity) and human activities (mining and smelting, use of antimony containing products, fossil fuel combustion, etc.). Similar to many elements, the toxicity of antimony is closely related to its chemical form, and the toxicity of Sb(III) is much higher than Sb(V). Antimony exists in various chemical forms in the environment (mainly Sb(III) and Sb(V)), and its environmental chemical behavior is easily affected by various environmental factors. Redox conditions can change the chemical form of antimony and affect its migration and transformation in environmental media. Once the antimony minerals are oxidized in contact with the air, antimony will be released in a dissolved state, and then attached to the surface of various solid particles in the tailings in the form of adsorption. It is easy to migrate and diffuse to the surrounding environment under the leaching of surface water, and absorbed by plant roots. In addition, this review also emphasizes the detection methods of antimony, in which the development of combined technology is an increasingly attractive research field in antimony speciation analysis. Finally, we provide several commonly used Sb removal technologies, and critically analyze the remarkable characteristics and removal mechanism of these technologies, hoping to provide reference for the treatment and research of antimony pollution.
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Co-application of titanium dioxide nanoparticles (TiO2 NPs) and plant growth promoting rhizobacteria (PGPR) to promote phytoremediation of Cd contaminated soil was studied. Seedlings of Trifolium repens were exposed to different doses of TiO2 NPs (0, 100, 250, 500 and 1000 mg/kg) and the PGPR, separately and in combination, to investigate the effects on plant growth, Cd uptake and accumulation and chlorophyll content of the plant. Co-application of TiO2 NPs and the PGPR enhanced plant growth and chlorophyll content of T. repens. Cd concentration in roots of T. repens reached 120.3 mg/kg in PGPR + 500 mg/kg TiO2 NPs treatment. Addition of TiO2 NPs to soil significantly increased accumulation capacity of T. repens. The greatest accumulation capacity of 1235 µg/pot was achieved for Cd in PGPR + 500 mg/kg TiO2 NPs treatment. Adverse impacts of using 1000 mg/kg TiO2 NPs were found on plant growth. Co-application of TiO2 NPs and PGPR could reduce the required amounts of TiO2 NPs for phytoremediation of heavy metal polluted soils. Co-application of TiO2 NPs and PGPR promoted growth of T. repens in Cd-contaminated soil and enhanced Cd uptake and accumulation by the plant. Intelligent association of plants, nanomaterials and PGPR have great application prospect in soil remediation.
Article
This study investigated the long-term leachability of antimony (Sb) in a smelting residue immobilized by three commercial micro-sized zero-valent iron (ZVI) products. Effect of oxic incubation time (14 days and 120 days) on the immobilization efficiency of Sb were compared, and the long-term leaching risk was evaluated by an accelerated exposure test, in which the slag was consecutively extracted by simulated strong acid rain (SSAR, HNO3: H2SO4 = 1:2, pH = 3.20). Notably, all ZVI treatments efficiently immobilized the Sb in this slag in a short term (14 days); the one-step SSAR-leached Sb was reduced by 89%–91% compared to the original slag (5.9 mg/L) and was far below the environmental standard (0.6 mg/L) established by the US EPA. The sequential SSAR leaching results reflected that the 14-d incubated slags after ZVI treatments had strong H⁺ resistance, and the immobilized Sb was not easily activated by continuous SSAR corrosion. The binding of Sb with amorphous phase Fe oxyhydroxides (e.g. ferrihydrite) derived from ZVI corrosion played a dominant role in the Sb immobilization efficiency. However, the longer aging process (120 days) easily resulted in the reduction of Sb immobilization by ZVI treatments. The changes in crystallinity of Fe oxyhydroxides (transformation from poorly-crystalline to crystalline ones) and the pH elevation to alkaline range might explain the weakening of the immobilization of Sb in ZVI-amended slags with 120 days of incubation. In total, the effectiveness of Sb immobilization in smelting residue greatly depended on the type of ZVI and the aging process. Our work has demonstrated that the ZVI treatment was potentially feasible to mitigate the Sb leaching risk from smelting slags; however, the ZVI type needs to be carefully selected and its long-term performance should be adequately verified before practical application.
Article
The present work was the first exploration of the use of industrial byproducts from iron and titanium processing as sorbents for the stabilization of soil contamination. The main aim was to test slag waste and iron-rich charred fossil coal (“Fe-char”), as sorbents for per- and polyfluorinated alkyl substances (PFASs), as well as lead (Pb) and antimony (Sb), in four soils from a firefighting training area (PFASs) and a shooting range (Pb and Sb). Adding slag (10–20%) to shooting range soils decreased the leaching of Pb and Sb up to 50–90%. Fe-char amendment to these soils resulted in a moderate reduction in Sb leaching (20–70%) and a slightly stronger effect on Pb (40–50%). The sorption is most likely explained by the presence of Fe oxyhydroxides. These are present in the highest concentrations in the slag, probably resulting in more effective metal binding to the slag than to the Fe-char. Fe-char but not slag proved to be a strong sorbent for PFASs (reducing PFAS leaching from the soil by up to 99.7%) in soil containing low total organic carbon (TOC; 1.2%) but not in high-TOC soil (34%). The sorption coefficient KD for Fe-char was high, in the range of 104.3 to 106.5 L/kg at 1 ng/L in the low-TOC soil. The KD value increased with increasing perfluorocarbon chain length, exceeding PFAS sorption to biochar in the low ng/L concentration range. This result indicates that the mechanism behind the strong PFAS sorption to Fe-char was mainly van der Waals dispersive interactions between the hydrophobic PFAS-chain and the aromatic π-electron systems on nanopore walls within the Fe-char matrix. Overall, this study indicates that industrial byproducts can provide sustainable and cost-effective materials for soil remediation. However, the sorbent needs to be tailored to the type of soil and type of contamination.
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Lead has been widely introduced into the environment for centuries and lead toxicity has been well known for decades. Despite hundreds of articles describing lead's interaction with the environment, questions continue to be raised regarding the extent to which the element may migrate through soil and the vadose zone and contaminate groundwater. The authors examined lead geochemistry and field data and conclude that lead may migrate short distances in surface and pore water but that reports of lead in groundwater are related to vanishingly low natural concentrations, direct introduction of lead, or errors during sample handling or analysis.
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Due to impact and abrasion of projectiles firing berms of shooting ranges frequently exhibit increased levels of bullet-borne contaminants. Stabilisation of backstop soils may be a promising pre- and post-use treatment to minimise leaching and bioavailability. This study focused on mobility and phytotoxicity of antimony, copper, and lead in stabilised berm material compared to an untreated control. Ferric (goethite, deferrisation sludge) and phosphatic amendments (diammonium phosphate, calcium dihydrogen phosphate) were used. Batch and column experiments demonstrated effective stabilisation of the contaminants by ferric amendments. Sequential extractions showed an increase of contaminant fractions associated with iron (hydr)oxides. Stabilisation was accompanied by a detoxification of seepage water compared to the control soil as shown by Duckweed growth inhibition. Contrasting the ferric additives, phosphatic amendments effectively stabilised lead but mobilised copper and antimony possibly due to a competitive displacement process. Thereby, benefits of lead stabilisation were completely overridden; this was underlined by increased phytotoxicity relative to the untreated soil. Overall, understanding stabilised soil as a multicomponent system is a prerequisite for the choice of appropriate amendments. This requires the synopsis of results from complementary test methods and a screening for a wide range of substances.
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Despite the rapidly growing concern about antimony pollution of waters and soils, the effect of organic matter on the behavior of this toxic trace element is poorly understood because of a lack of data on SbV-organic ligand interactions in aqueous solution. We used in situ potentiometry and X-ray absorption spectroscopy (XAS) to measure in aqueous solution at ambient conditions the stability and structure of aqueous complexes formed by pentavalent antimony (SbV) with low molecular weight organic ligands, such as carboxylic acids (acetic, adipic, malonic, lactic, oxalic, citric and salicylic), phenols (catechol), polyols (xylitol and mannitol), and amines (glycine), which have O- and N-functional groups typical of natural organic matter. Potentiometric titrations from pH 2 to 10 demonstrate negligible SbV complexing with amine and carboxylic acids with single functional group (acetic acid) or non-adjacent functional groups (adipic acid). In contrast, SbV forms stable complexes with poly-carboxylic, hydroxy-carboxylic acids, and with aliphatic and aromatic polyol ligands in the pH range typical of natural waters. XAS measurements show that in these species the SbV atom has a distorted octahedral geometry composed of 6 oxygen atoms forming a five- or six-membered bidendate cycle. Stability constants of SbV-organic complexes, generated for the first time in this study, were used to model SbV binding with natural humic acids containing the same functional groups as those used in this work. Our predictions of SbV binding with natural humic acids indicate that in an aqueous organic-rich solution of 1 μg L− 1 Sb and 20 mg L− 1 dissolved organic carbon (DOC) up to 40% of total Sb binds to aqueous organic matter via carboxyl and hydroxy-carboxyl functional groups at pH ≤ 4, whereas at neutral-to-basic pH this amount does not exceed 5%. These estimations are in agreement with direct dialysis measurements conducted with a purified commercial humic acid. The low affinity of SbV to organic matter at near-neutral pH contrasts with that of SbIII whose organic complexes may account up to 80% of total Sb in DOC-rich waters. The large differences in SbIII versus SbV binding to organic matter may be used for tracing in organic-rich sediments and waters the two main Sb oxidation states, which have different toxicities for aquatic organisms.
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Published studies where antimony association with colloidal and particulate phases is studied in waters, soils and sediments are reviewed. The techniques considered range from the simple calculation of partition coefficients, the application of size-based speciation methods or sequential extraction techniques to the use of more sophisticated techniques such as X-ray absorption spectroscopy (XAS). What these methods have in common is that they are applied directly to bulk samples and that, with the exception of XAS, they give operationally defined results, which are very often difficult to interpret and compare. In the case of the extraction methods, which are the most commonly used, this difficulty is compounded by the tendency of many authors to endlessly modify the experimental procedures. Antimony does not seem to associate to any significant extent with colloidal and particulate phases in waters. However, at the same time, it appears not to be easily extractable from soils where, even if it is usually present to a certain extent in ‘iron oxide’ fractions in sequential extraction methods, most remains in the so called ‘residual’ fraction. Unfortunately, the direct application of XAS techniques to real environmental samples, which could help to clarify antimony binding by solid phases, is precluded in most systems because of their insensitivity; only a few heavily polluted systems have been studied so far using these techniques. In these studies antimony is present as Sb(V) in soils and significantly bound by iron oxide phases.
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We studied three Finnish shooting ranges in order to define the extent of the risks associated with elevated environmental concentrations of metals and PAHs. A scoring system revealed that lead, arsenic, and antimony were the most critical contaminants. On Site 3, the concentration of lead in groundwater exceeded the drinking water standard indicating evident health risks. For the remaining two sites we calculated Acceptable Daily Doses (ADD) based on the Reasonable Maximum Exposure (RME) approach and compared them with safe exposure levels. We also used a pharmacokinetic model to determine blood lead levels (PbBs). Risks to biota were assessed using ecological benchmarks and exposure and accumulation models. Prediction of leaching was based on laboratory tests and a distribution model. The health risk assessment for lead resulted in the maximum hazard quotient (HQ) of 1.2 whereas the HQs of As and Sb remained less than 1. Some exposure scenarios produced PbB estimates exceeding 10 μ g dl-1 but based on the uncertainty analysis we expect the health risks to remain insignificant. However, leaching of contaminants presents a risk to groundwater quality. At site 1 the ecotoxicity-based HQs demonstrate high risks to soil biota, small mammals, terrestrial plants and aquatic organisms.
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This article is a state-of-the-art review about such metals as Al, Fe, Mn, Cu, Zn, Cd, Pb, Cr, Ni, Hg, and As in surface waters. It focuses on natural and anthropogenic sources, chemical properties and levels, and toxicity mechanisms of these metals to aquatic organisms, primarily fish and invertebrates. Organisms living in almost anoxic, sulfide-rich evironments are not incorporated into this study. This information is then linked to a Nordic Lake Survey implemented in 1995 on major chemistry and metals in Scandinavian surface waters to scale the problems of metals in Swedish and Norwegian surface waters. Because many acidified Swedish and Norwegian lakes also are limed, we also assess the risk of remobilization of metals because these waters reacidify due to reduced liming activity. The concentrations and chemical properties of metals in lakes relative to the biological effect levels suggest that the potential risks associated to both current and potential reacidified status of limed waters decreases in the order Al >> Cd > Pb in Swedish and Norwegian lakes. Also Hg, because of the organometallic forms such as methylmercury (MeHg), might be of concern, because it biomagnifies in the food chain and subsequently of great importance for top predators, including human beings. However, other factors than pH, such as changes in organic matter load from the surrounding soils due to natural climatic variations, are much more important for the Hg load and thereby the Hg concentrations in lakes than pH. The risks associated with other metals such as Cu, Fe, Mn, Ni, and Zn are very low and have to be considered only occasionally, because high concentrations are very rare in Norwegian and Swedish lakes. Less than 2% of the lakes have concentrations ≥ the lowest biological risk levels quoted in the two countries. Because primarily As is present as anions in surface waters, this element differs significantly from the cationic metals. Only a few lakes have high As concentration in relation to critical levels in Sweden, and high As concentrations are mainly related to agricultural areas and consequently high pH waters.
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The distribution of Sb in a variety of sample materials, including soils, plants and surface water, was studied at different scales, from continental to local, combining published data sets with the aim of delineating the impact and relative importance of geogenic vs. anthropogenic Sb sources. Geochemical mapping demonstrates that variation is high at all scales – from the detailed scale with sample densities of many sites per km² to the continental-scale with densities of 1 site per 5000 km². Different processes govern the Sb distribution at different scales. A high sample density of several samples per km² is needed to reliably detect mineralisation or contamination in soil samples. Median concentrations are so low for Sb in most sample materials (below 1 mg/kg in rocks and soils, below 0.1 mg/kg in plants, below 0.1 μg/L in surface water) that contamination is easier to detect than for many other elements. Distribution patterns on the sub-continental to continental-scale are, however, still dominated by natural variation. Given that the geochemical background is characterised by a high variation at all scales, it appears impossible to establish a reliable single value for “good soil quality” or a “natural background concentration” for Sb for any sizeable area, e.g., for Europe. For such a differentiation, geochemical maps at a variety of scales are needed.
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Sequential selective extraction techniques are commonly used to fractionate the solid-phase forms of metals in soils. Many sequential extraction procedures have been developed, particularly for sediments or agricultural soils, and, despite numerous criticisms, they remain very useful. This article reviews the reagents used in the various schemes, with their advantages and disadvantages. The particular case of elements giving anionic species is also developed. Finally, there is discussion of the limits of sequential extraction procedures.
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Metals are common contaminants worldwide. Long-term deposition of metals in soils can lead to accumulation, transport and biotoxicity/zootoxicity caused by mobility and bioavailability of significant fraction of the metals. Contaminant bioavailability is increasingly being used as a key indicator of potential risk that contaminants pose to both environmental and human health. However, the definition of bioavailability and the concepts on which it is based are still unclear, the methods adopted for its measurement vary and as such there is no single standard technique for the assessment of either plant availability of contaminants or their ecotoxicological impacts on soil biota. Moreover, bioavailability is often assumed to be static in nature where most decisions on risk and remediation are based on laboratory estimations of the bioavailable fraction, which may vary with time, nature of species as well as with temporal variation in environmental factors. Because of their immutable nature, strict natural attenuation processes alone may not be sufficient in mitigating the risks from metals. However, accelerating these processes with human interference (i.e., assisted natural remediation) that effectively immobilizes metals might be a viable option. Application to soils of certain amendments that enhance key biogeochemical processes in soils that effectively immobilize metals have already been demonstrated in Europe and North America on a field scale. Case studies using lime, phosphate and biosolid amendments have demonstrated, under field conditions, enhanced natural remediation resulting in substantially improved vegetation growth, invigorated microbial population and diversity, and reduced offsite metal transport. Depending on soil/hydrogeochemical properties, source term and metal form/species, and land use, the immobilization efficacy induced by such assisted natural remediation may be enduring. The use of green plants as a remediation tool in environmental cleanup has also offered some potential. Plants can uptake and bioaccumulate (phytoextraction) as well as immobilize (phytoimmobilization) certain trace elements, in conjunction with their rhizospheric processes. While long-term stability of certain metal complexes, such as metal pyromorphites has been shown in model systems, the influence of plant roots and its microbial and mycorrhizal association on such stability is unknown. A suite of chemical and biological tests are available to monitor the efficacy of assisted natural remediation.
Article
Antimony (Sb) in lead bullets poses a major environmental risk in shooting range soils. Here we studied the effect of iron (Fe)-based amendments on the mobility of Sb in contaminated soil from shooting ranges in Norway. Untreated soil showed high Sb concentrations in water extracts from batch tests (0.22-1.59 mg L-1) and soil leachate from column tests (0.3 - 0.7 mg L-1), occurring exclusively as Sb(V). Sorption of Sb to different iron-based sorbents was well described by the Freundlich equation (Fe2(SO4)3, log KF=6.35, n=1.51; CFH-12 (Fe oxyhydroxide), log KF=4.16 - 4.32, n=0.75-0.76); Fe0 grit, log KF=3.26, n=0.47). These sorbents mixed with soil (0.5 and 2% w/w), showed significant sorption of Sb in batch tests (46 - 92 %). However, for Fe2(SO4)3 and CFH-12 liming was also necessary to prevent mobilization of lead, copper and zinc. Column tests showed significant retention of Sb (89 - 98%) in soil amended with CFH-12 (2%) mixed with limestone (1%) compared to unamended soil. The sorption capacity of soils amended with Fe0 (2%) increased steadily up to 72% over the duration period of the column test (64 days), most likely due to the gradual oxidation of Fe0 to Fe oxyhydroxides. Based on the experimental results, CFH-12 and oxidized Fe0 are effective amendments for the stabilization of Sb in shooting range soils.
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【Summary】 Humic substances (HSs) are by far the most abundant of the organic components of nature, and are present in all soils and natural waters that contain organic matter. The more widely accepted values for organic carbon (OC) in soil organic matter (SOM) are in the range of (14~15)×10 17
Article
An analytical procedure involving sequential chemical extractions has been developed for the partitioning of particulate trace metals (Cd, Co, Cu, Nl, Pb, Zn, Fe, and Mn) into five fractions: exchangeable, bound to carbonates, bound to Fe-Mn oxides, bound to organic matter, and residual. Experimental results obtained on replicate samples of fluvial bottom sediments demonstrate that the relative standard deviation of the sequential extraction procedure is generally better than ± 10%. The accuracy, evaluated by comparing total trace metal concentrations with the sum of the five individual fractions, proved to be satisfactory. Complementary measurements were performed on the individual leachates, and on the residual sediments following each extraction, to evaluate the selectivity of the various reagents toward specific geochemical phases. An application of the proposed method to river sediments is described, and the resulting trace metal speciation is discussed.
Chapter
IntroductionSystem structure and limitationsMethods and data requirementsClassification of environmental quality status