Special Issue "Soil Contamination by Heavy Metals and Metalloids"

A special issue of Environments (ISSN 2076-3298).

Deadline for manuscript submissions: closed (30 September 2020).

Special Issue Editor

Dr. Dionisios Gasparatos
E-Mail Website
Guest Editor
Laboratory of Soil Science and Agricultural Chemistry, Department of Natural Resources and Agricultural Engineering, Agricultural University of Athens, Greece
Interests: pedology; soil genesis and mineralogy; soil fertility and plant nutrition; environmental chemistry and geochemistry; organic agriculture and soil properties; soil pollution; heavy metals in the soil–plant system

Special Issue Information

Dear Colleagues,

As Guest Editor, I have the pleasure of inviting you to participate in this Special Issue of Environments covering high-impact research regarding ‘’Soil Contamination by Heavy Metals and Metalloids’’.

Heavy metals and metalloids include cadmium (Cd), lead (Pb), selenium (Se), mercury (Hg), arsenic (As), chromium (Cr), copper (Cu), nickel (Ni), silver (Ag), zinc (Zn), cesium (Cs), and cobalt (Co). Unlike organic contaminants, heavy metal(loid)s do not biodegrade and persist for a long time in the soil system.

Soil is one of the most valuable resources on earth, providing, for example, food and fiber production, climate and gas regulation, carbon sequestration, and raw materials. Soil contamination has been identified and as one of the main soil threats inducing the degradation of global soils and driving long-term losses of ecosystems services provided by them. As a result of human activities, the level of soil contamination by heavy metal(loid)s has severely increased over the last few decades and has become a worldwide environmental issue that has attracted considerable public attention.

The aim of this Special Issue is to highlight soil contamination as a global threat, providing an overview of its importance, the need for additional information from different world regions, and the urgency of developing concrete strategies to address the causes and impacts of this major threat.  I especially encourage papers on the development of novel science-based methods and applications that enhance the remediation of contaminated soils and mitigate the ecological hazards caused by heavy metal(loid)s in soils.

Articles may include but are not limited to the following topics:

  • The identification of the main sources of soil contamination by heavy metal(loid)s in different soil types;
  • Chemistry, speciation, potential mobility, and the bioavailability of heavy metal(loid)s commonly found in contaminated soils;
  • Assessment of negative impacts and risks of soil heavy metal(loid)s contamination on crop yields, soil biota, food security, and human health;
  • Available methods and strategies for monitoring, assessing, and remediating contaminated soils by heavy metal(loid)s;
  • Guidelines that include threshold values for heavy metal(loid)s in soils on national and regional levels.

For researchers looking to advance science in ‘’Soil Contamination by Heavy Metals and Metalloids’’, this Special Issue of Environments will provide a well-supported forum to share high-impact papers.

Dr. Dionisios Gasparatos
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Environments is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • status of soil contamination by heavy metal(loid)s on national and regional levels
  • assessment of heavy metal(loid)s contamination in agricultural soils
  • factors affecting heavy metal(loid)s mobility and bioavailability in soils
  • heavy metal(loid)s in urban soils
  • remediation strategies and techniques
  • ecological risk assessment of heavy metal(loid)s in soils

Published Papers (6 papers)

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Research

Article
Influence of Biochar Derived Nitrogen on Cadmium Removal by Ryegrass in a Contaminated Soil
Environments 2021, 8(2), 11; https://doi.org/10.3390/environments8020011 - 08 Feb 2021
Viewed by 784
Abstract
Little is known about the effect of nitrogen (N) application via biochar on the removal of trace elements by crops, and the effects with chemical fertilizers are inconsistent. We determined, from a previous study, the influence of increased N addition via biochars produced [...] Read more.
Little is known about the effect of nitrogen (N) application via biochar on the removal of trace elements by crops, and the effects with chemical fertilizers are inconsistent. We determined, from a previous study, the influence of increased N addition via biochars produced from switchgrass (SGB) and poultry litter (PLB) on cadmium (Cd) removal by ryegrass. The biochar rates of 0, 0.5, 1, 2, and 4% w/w were applied to a Cd-contaminated soil before seeding in a potting experiment with a complete randomized block design (CRBD). Ryegrass yield and N and Cd removed by harvest were strongly related (p < 0.05). The ryegrass yields increased up to 1% of PLB, and Cd removal was also the highest at 1% of PLB. The biomass of ryegrass roots increased with Cd accumulation (p < 0.05). Overall, the Cd transfer factor (TF) from ryegrass roots to shoots increased when up to 206 ± 38 kg N ha−1 was removed in ryegrass shoots (p < 0.0001). The application of PLB up to 1% might be a viable option since it is a practical rate for handling operations requiring less volume of material than SGB. Additionally, the Cd concentration in the aboveground forage remained acceptable for grazing cattle. Future studies are encouraged to evaluate different sources of N fertilizers affecting Cd uptake on cash crops. Full article
(This article belongs to the Special Issue Soil Contamination by Heavy Metals and Metalloids)
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Article
Measuring Soil Metal Bioavailability in Roadside Soils of Different Ages
Environments 2020, 7(10), 91; https://doi.org/10.3390/environments7100091 - 15 Oct 2020
Viewed by 1049
Abstract
Finding a reliable method to predict soil metal bioavailability in aged soil continues to be one of the most important problems in contaminated soil chemistry. To investigate the bioavailability of metals aged in soils, we used roadside soils that had accumulated metals from [...] Read more.
Finding a reliable method to predict soil metal bioavailability in aged soil continues to be one of the most important problems in contaminated soil chemistry. To investigate the bioavailability of metals aged in soils, we used roadside soils that had accumulated metals from vehicle emissions over a range of years. We collected topsoil (0–10 cm) samples representing new-, medium- and old-aged roadside soils and control site soil. These soils were studied to compare the ability of the diffusive gradients in thin films technique (DGT), soil water extraction, CaCl2 extraction, total metal concentrations and optimised linear models to predict metal bioavailability in wheat plants. The response time for the release of metals and the effect on metal bioavailability in field aged soils was also studied. The DGT, and extractable metals such as CaCl2 extractable and soil solution metals in soil, were not well correlated with metal concentrations in wheat shoots. In comparison, the strongest relationships with concentrations in wheat shoots were found for Ni and Zn total metal concentrations in soil (e.g., Ni r = 0.750, p = 0.005 and Zn r = 0.833, p = 0.001); the correlations were still low, suggesting that total metal concentrations were also not a robust measure of bioavailability. Optimised linear models incorporating soil physiochemical properties and metal extracts together with road age as measure of exposure time, demonstrated a very strong relationship for Mn R2 = 0.936; Ni R2 = 0.936 and Zn R2 = 0.931. While all the models developed were dependent on total soil metal concentrations, models developed for Mn and Zn clearly demonstrated the effect of road age on metal bioavailability. Therefore, the optimised linear models developed have the potential for robustly predicting bioavailable metal concentrations in field soils where the metals have aged in situ. The intrinsic rate of release of metals increased for Mn (R2 = 0.617, p = 0.002) and decreased for Cd (R2 = 0.456, p = 0.096), Cu (R2 = 0.560, p = 0.083) and Zn (R2 =0.578, p = 0.072). Nickel did not show any relationship between dissociation time (Tc) and road age. Roadside soil pH was likely to be the key parameter controlling metal aging in roadside soil. Full article
(This article belongs to the Special Issue Soil Contamination by Heavy Metals and Metalloids)
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Article
Adsorption/Desorption Patterns of Selenium for Acid and Alkaline Soils of Xerothermic Environments
Environments 2020, 7(10), 72; https://doi.org/10.3390/environments7100072 - 24 Sep 2020
Viewed by 978
Abstract
Selenium adsorption/desorption behavior was examined for eight Greek top soils with different properties, aiming to describe the geochemistry of the elements in the selected soils in terms of bioavailability and contamination risk by leaching. Four soils were acid and four alkaline, and metal [...] Read more.
Selenium adsorption/desorption behavior was examined for eight Greek top soils with different properties, aiming to describe the geochemistry of the elements in the selected soils in terms of bioavailability and contamination risk by leaching. Four soils were acid and four alkaline, and metal oxides content greatly differed between the two groups of soils. The concentrations of Se(IV) used for the performed adsorption batch experiments ranged from 1 to 50 mg/L, while the soil to solution ratio was 1 g/0.03 L. Acid soils adsorbed significantly higher amounts of the added Se(IV) than alkaline soils. Freundlich and Langmuir equations adequately described the adsorption of Se(IV) in the studied soils, and the parameters of both isotherms significantly correlated with soil properties. In particular, both KF and qm values significantly positively correlated with ammonium oxalate extractable Fe and with dithionite extractable Al and Mn, suggesting that amorphous Fe oxides and Al and Mn oxides greatly affect exogenous Se(IV) adsorption in the eight soils. These two parameters were also significantly negatively correlated with soil electrical conductivity (EC) values, indicating that increased soluble salts concentration suppresses Se(IV) adsorption. No significant relation between adsorbed Se(IV) and soil organic content was recorded. A weak salt (0.25 M KCl) was used at the same soil to solution ratio to extract the amount of the adsorbed Se(IV) that is easily exchangeable and thus highly available in the soil ecosystem. A much higher Se(IV) desorption from alkaline soils was observed, pointing to the stronger retention of added Se(IV) by the acid soils. This result implies that in acid soils surface complexes on metal oxides may have been formed restricting Se desorption. Full article
(This article belongs to the Special Issue Soil Contamination by Heavy Metals and Metalloids)
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Article
Alleviation of Cadmium Adverse Effects by Improving Nutrients Uptake in Bitter Gourd through Cadmium Tolerant Rhizobacteria
Environments 2020, 7(8), 54; https://doi.org/10.3390/environments7080054 - 26 Jul 2020
Cited by 13 | Viewed by 1872
Abstract
Cadmium is acute toxicity inducing heavy metal that significantly decreases the yield of crops. Due to high water solubility, it reaches the plant tissue and disturbs the uptake of macronutrients. Low uptake of nutrients in the presence of cadmium is a well-documented fact [...] Read more.
Cadmium is acute toxicity inducing heavy metal that significantly decreases the yield of crops. Due to high water solubility, it reaches the plant tissue and disturbs the uptake of macronutrients. Low uptake of nutrients in the presence of cadmium is a well-documented fact due to its antagonistic relationship with those nutrients, i.e., potassium. Furthermore, cadmium stressed plant produced a higher amount of endogenous stress ethylene, which induced negative effects on yield. However, inoculation of 1-amino cyclopropane-1-carboxylate deaminase (ACCD), producing plant growth promoting rhizobacteria (PGPR), can catabolize this stress ethylene and immobilized heavy metals to mitigate cadmium adverse effects. We conducted a study to examine the influence of ACCD PGPR on nutrients uptake and yield of bitter gourd under cadmium toxicity. Cadmium tolerant PGPRs, i.e., Stenotrophomonas maltophilia and Agrobacterium fabrum were inoculated solely and in combination with recommended nitrogen, phosphorus, and potassium fertilizers (RNPKF) applied under different concentration of soil cadmium (2 and 5 mg kg−1 soil). Results showed that A. fabrum with RNPKF showed significant positive response towards an increase in the number of bitter gourds per plant (34% and 68%), fruit length (19% and 29%), bitter gourd yield (26.5% and 21.1%), N (48% and 56%), and K (72% and 55%) concentration from the control at different concentrations of soil cadmium (2 and 5 mg kg−1 soil), respectively. In conclusion, we suggest that A. fabrum with RNPKF can more efficaciously enhance N, K, and yield of bitter gourd under cadmium toxicity. Full article
(This article belongs to the Special Issue Soil Contamination by Heavy Metals and Metalloids)
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Article
Short- and Long-Term Biochar Cadmium and Lead Immobilization Mechanisms
Environments 2020, 7(7), 53; https://doi.org/10.3390/environments7070053 - 16 Jul 2020
Cited by 1 | Viewed by 1506
Abstract
The mechanisms of soil Cd and Pb alterations and distribution following biochar (BC; 0 to 40 t ha−1) amendments applied (in either 2009 [long-term] or in 2016 [short-term]) to a contaminated rice paddy soil, and subsequent plant Cd and Pb tissue [...] Read more.
The mechanisms of soil Cd and Pb alterations and distribution following biochar (BC; 0 to 40 t ha−1) amendments applied (in either 2009 [long-term] or in 2016 [short-term]) to a contaminated rice paddy soil, and subsequent plant Cd and Pb tissue distribution over time was investigated. Water-soluble Cd and Pb concentrations decreased by 6.7–76.0% (short-term) and 10.3–88.1% (long-term) with biochar application compared to the control. The soil exchangeable metal fractions (i.e., considered more available) decreased, and the residual metal fractions (i.e., considered less available) increased with short- and long-term biochar amendments, the latter likely a function of biochar increasing pH and forcing Cd and Pb to form crystal mineral lattice associations. Biochar application reduced Cd (16.1–84.1%) and Pb (4.1–40.0%) transfer from root to rice grain, with rice Cd and Pb concentrations lowered to nearly Chinese national food safety standards. Concomitantly, soil organic matter (SOM), pH and soil water content increased by 3.9–49.3%, 0.05–0.35 pH units, and 3.8–77.4%, respectively, with increasing biochar application rate. Following biochar applications, soil microbial diversity (Shannon index) also increased (0.8–46.2%) and soil enzymatic activities were enhanced. Biochar appears to play a pivotal role in forcing Cd and Pb sequestration in contaminated paddy soils, reducing heavy metal transfer to rice grain, and potentially leading to reduced heavy metal consumption by humans. Full article
(This article belongs to the Special Issue Soil Contamination by Heavy Metals and Metalloids)
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Article
Potentially Toxic Elements in Urban Soils of Havana, Cuba
Environments 2020, 7(6), 43; https://doi.org/10.3390/environments7060043 - 09 Jun 2020
Cited by 3 | Viewed by 1944
Abstract
Urban soils are characterised by a strong anthropogenic influence. Potentially toxic elements were studied in various horizons of 35 urban soils in Havana, Cuba, classified as Urbic or Garbic Technosols. Pseudo-total, available, and acid-oxalate extractable concentrations were determined. The pseudo-total concentrations were generally [...] Read more.
Urban soils are characterised by a strong anthropogenic influence. Potentially toxic elements were studied in various horizons of 35 urban soils in Havana, Cuba, classified as Urbic or Garbic Technosols. Pseudo-total, available, and acid-oxalate extractable concentrations were determined. The pseudo-total concentrations were generally higher than the average values for the world’s soils but similar to those published for urban soils. In a few cases, very high values of copper or lead were found. Nickel and chromium concentrations exceeded the maximum allowable concentrations for agricultural soils in 22% and 12% of samples. Vanadium concentrations were always very high. There was minimum enrichment of most samples in Co, Mn, As, Cd, Cr, Cu, and Ni, but outliers reached moderate or significant enrichment. Enrichment was significant for V, while for Pb, Zn, and Hg the median values denoted moderate enrichment, but outliers reached significant enrichment in Zn and extremely high enrichment in Pb and Hg. The available elements amounted to between 0.07% of the pseudo-total vanadium and 30% lead and cadmium. The published toxicity limits for bioavailable Cd, Mn, Ni, and Pb were exceeded in 14%, 39%, 10%, and 56% of samples, respectively. The concentrations of pseudo-total total iron, cobalt, chromium, and nickel, and available cobalt, nickel and titanium were significantly lower in soils with gleyic properties (reducing conditions). Full article
(This article belongs to the Special Issue Soil Contamination by Heavy Metals and Metalloids)
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