The major frequent contaminants in soil are heavy metals which may be responsible for detrimental health effects. The remediation of heavy metals in contaminated soils is considered as one of the most complicated tasks. Among different technologies, in situ immobilization of metals has received a great deal of attention and turned out to be a promising solution for soil remediation. In this review, remediation methods for removal of heavy metals in soil are explored with an emphasis on the in situ immobilization technique of metal(loid)s. Besides, the immobilization technique in contaminated soils is evaluated through the manipulation of the bioavailability of heavy metals using a range of soil amendment conditions. This technique is expected to efficiently alleviate the risk of groundwater contamination, plant uptake, and exposure to other living organisms. The efficacy of several amendments (e.g., red mud, biochar, phosphate rock) has been examined to emphasize the need for the simultaneous measurement of leaching and the phytoavailability of heavy metals. In addition, some amendments that are used in this technique are inexpensive and readily available in large quantities because they have been derived from bio-products or industrial by-products (e.g., biochar, red mud, and steel slag). Among different amendments, iron-rich compounds and biochars show high efficiency to remediate multi-metal contaminated soils. Thereupon, immobilization technique can be considered a preferable option as it is inexpensive and easily applicable to large quantities of contaminants derived from various sources.

Remediation of soils contaminated with heavy metals with an emphasis on immobilization technology

Remediation of heavy metals by reducing their mobility and bioavailability without removing them from soils is considered to be a cost-effective and an efficient method to address their toxicity for living organisms and soil health. The main objectives of the current study, therefore, were to investigate the potential of sugarcane bagasse biochar in reducing the bioavailability of soil cadmium (Cd) and chromium (Cr) and assessing the impact of biochar application on soil microbial activities and plant growth in metal-contaminated soil. Air-dried soil was artificially spiked with Cd and Cr metals by using Cd(NO3)2 and Cr(NO3)2 solutions. Biochar was homogenously mixed in metal-spiked soil. The experimental spiked soil was categorized as with and without biochar-amended soil. Mash bean crop was used as test plant. After crop harvesting, soil Cd and Cr were extracted by diethylenetriaminepentaacetic acid (DTPA) to estimate the mobility of heavy metals. Furthermore, the plant metal contents, microbial biomass carbon, urease activity, dehydrogenase (DHA) activity, total organic carbon, and plant biomass were determined. The Langmuir adsorption isotherms were studied for Cd and Cr in unamended soil, biochar-amended soil, and biochar only. The electronegative charges of biochar and biochar-amended soil were also measured using the zeta potential. The results show that the application of biochar to Cr- and Cd-contaminated soil significantly reduced their availability by 85 and 63%, respectively. The application of biochar at 15 g kg−1 prominently reduced the extractable Cd contents by 29 and 32% in Cd-contaminated and Cr–Cd-contaminated soils, respectively. The Cr concentration in the plant decreased by 34 and 41% in Cr-contaminated and Cr–Cd-contaminated soil compared with spiked soil without biochar. The Langmuir model achieved the best fit; its isotherm predicted the biochar’s maximum adsorption capacity for Cd (0.42 mg g−1) and Cr (0.35 mg g−1). Biochar incorporation in Cd–Cr-contaminated soil significantly increased the microbial activity and mash bean biomass. Our findings indicate that the addition of sugarcane bagasse-derived biochar significantly reduces the Cd and Cr availability in single and co-contaminated soil. In addition, an increase in the microbial activity and plant growth and a significant reduction in the Cd and Cr uptake by mash bean are possible after biochar addition.

Sugarcane bagasse-derived biochar reduces the cadmium and chromium bioavailability to mash bean and enhances the microbial activity in contaminated soil

Restoration of soil quality using biochar and brown coal waste: A review.

Agriculture has always remained backbone of economy and sociopolitical stability of low and middle income countries, and employs largest work force in India. Maintenance of soil quality has been pointed out as one of the major contributing factors for sustainability of agricultural production. Rising contribution of industry to India’s GDP has been speculated to cause adverse impact on the precious land resources; though the issue has received less attention among the policy makers. There is a complex relationship of Indian economy with industry and agriculture, both of which competing for same natural resources with differential impact on land resources. This chapter highlights the need for reviewing different developmental activities having direct or indirect impact on agricultural productivity and the need for accelarating soil research to investigate upon migration of pollutants from source of generation and their impact on soil so as to devise strategies for protection and remediation of precious non-renewable soil resources.

Soil Pollution - An Emerging Threat to Agriculture

The soil-gas diffusion is a primary driver of transport, reactions, emissions, and uptake of vadose zone gases, including oxygen, greenhouse gases, fumigants, and spilled volatile organics. The soil-gas diffusion coefficient, D p , depends not only on soil moisture content, texture, and compaction but also on the local-scale variability of these. Different predictive models have been developed to estimate D p in intact and repacked soil, but clear guidelines for model choice at a given soil state are lacking. In this study, the water-induced linear reduction (WLR) model for repacked soil is made adaptive for different soil structure conditions (repacked, intact) by introducing a media complexity factor ( C m ) in the dry media term of the model. With C m = 1, the new structure-dependent WLR (SWLR) model accurately predicted soil-gas diffusivity ( D p / D o , where D o is the gas diffusion coefficient in free air) in repacked soils containing between 0 and 54% clay. With C m = 2.1, the SWLR model on average gave excellent predictions for 290 intact soils, performing well across soil depths, textures, and compactions (dry bulk densities). The SWLR model generally outperformed similar, simple D p / D o models also depending solely on total and air-filled porosity. With C m = 3, the SWLR performed well as a lower-limit D p / D o model, which is useful in terms of predicting critical air-filled porosity for adequate soil aeration. Because the SWLR model distinguishes between and well represents both repacked and intact soil conditions, this model is recommended for use in simulations of gas diffusion and fate in the soil vadose zone, for example, as a key element in developing more accurate climate change models.

Structure-Dependent Water-Induced Linear Reduction Model for Predicting Gas Diffusivity and Tortuosity in Repacked and Intact Soil

Organic matter is able to bind heavy metals. Enrichment of soil with organic matter could reduce the content of bioavailable metal species as a result of complexation of free ions of heavy metals. This process could be used for remediation to protect plants against metal pollution. The experiments were carried out on Haplic Luvisols in field pots sunk into the ground. A brown coal preparation (the "Rekulter") was used as an amendment of soils artificially contaminated with Cd, Pb and Zn. A winter rye was used as the test plant. The total content of heavy metals and concentration of their bioavailable species in the soil were determined using 2M HNO3 and EDTA extraction, respectively. The content of bioavailable (soluble in EDTA) zinc, lead, cadmium in soil depended on the application rate of the "Rekulter" and decreased along with an increase in the amendment dosage. The highest efficiency of the "Rekulter" in preventing uptake of zinc, lead and cadmium by plants was observed for the largest dosage of this preparation. The bioaccumulation (BI) indexes of Cd, Pb, Zn indicate availability of Cd, Pb and Zn to plants. The BI decreased along with an increase in the brown coal amendment dosage.

The effect of organic matter from brown coal on bioavailability of heavy metals in contaminated soils

Organic matter takes part in all soil processes and influences the physical, chemical and biological properties of soil. The paper presents the analysis of heavy metal contents (Zn, Pb, Cd) in soil and biomass of darnel multifloral (Lolium multiflorum Lam.) cultivated at diverse conditions of soil reaction and organic matter content. A brown coal preparation (Rekulter) was applied as the source of organic matter in autumn 1999 to the studied soil, which was contaminated with cadmium, lead and zinc. The limiting influence of Rekulter on the uptake of heavy metals by darnel multifloral (two cuts of the test plant) was the highest in the case when the largest dose was applied to soil with the highest pH (about 6.0). Bioaccumulation indexes (BI) for Cd, Pb, Zn indicate the mobility and bioavailability of Cd, Pb and Zn in soils. The BI for particular heavy metals were generally low, with the lowest in the case when the largest dose of Rekulter was applied to all cuts of the test plant

Uptake of heavy metals by darnel multifloral (Lolium multiflorum Lam.) at diverse soil reaction and organic matter content

http://cejsh.icm.edu.pl/cejsh/element/bwmeta1.element.desklight-bdf88f06-b0cb-4be4-a467-1dd0dada1a24/c/PRM_2014-2_08_Maciejewska_Turek.pdf

Rewitalizacja obszarów poprzemysłowych ze szczególnym uwzględnieniem uwarunkowań środowiska przyrodniczego – wybrane studia przypadków

/pdf/problematyka-ochrony-gruntow-rolnych-w-procesie-4dtwcrzri1.pdf

Problematyka ochrony gruntów rolnych w procesie suburbanizacji

Varved clay deposits from ice-dammed lakes are a particularly important and broadly applied raw material used for the production of high-quality ceramics (red bricks, roof tiles, etc.), but the mineralogy and geochemistry of these sediments are not fully understood. The aim of the present study was to determine the chemical and mineralogical composition of ice-dammed lake sediments of the Lebork deposit. Major-element analysis of the compositions of selected samples from the ice-dammed lake clays was performed by X-ray fluorescence (XRF) and trace elements were determined by inductively coupled plasma-mass spectrometry. The mineralogical composition of clay samples was determined by X-ray diffraction (XRD). Analyses of the chemical composition of the ice-dammed lake clays of the Lebork deposit showed that the dominant component was SiO2 with a mean content of 56.13 wt.%; the second most abundant component was Al2O3, with a mean content for the entire deposit of 11.61 wt.%. Analysis by ICP-MS indicated the presence of rare earth elements (REE), e.g. cerium, neodymium, lanthanum, and praseodymium; their mean contents are: 56.9, 27.0, 26.3, and 7.3 ppm, respectively. Mineralogical analysis of the varved clays identified quartz, muscovite, calcite, and clay minerals – illite, kaolinite, and montmorillonite. The material filling the Lebork basin is characterized by small lateral and vertical variability in chemical composition. The results of the present study may be of considerable importance in determining the parent igneous, metamorphic, and sedimentary rocks, the weathering products of which supplied material to the ice-dammed lake, as well as in determining the mechanisms and character of the sedimentation process itself.

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Alina Maciejewska

Papers

The effect of organic matter from brown coal on bioavailability of heavy metals in contaminated soils

Uptake of heavy metals by darnel multifloral (Lolium multiflorum Lam.) at diverse soil reaction and organic matter content

Rewitalizacja obszarów poprzemysłowych ze szczególnym uwzględnieniem uwarunkowań środowiska przyrodniczego – wybrane studia przypadków

Problematyka ochrony gruntów rolnych w procesie suburbanizacji

Geochemistry and Mineralogy of Ice-Dammed Lake Sediments of the Lębork Deposit