Retention Of Heavy Metals Research Articles

Galvanic sludges: Effectiveness of red clay ceramics in the retention of heavy metals and effects on their technical properties.

Abstract Tiles of red clay mixed with 5% by weight of galvanic sludge were obtained by dry pressing, enameling in the line of production, and sintering in a semi-industrial roller kiln. In the process, a 30-minute firing cycle was employed at a temperature of 1170°C, with heating–cooling ramps between 47°C and 197°C. In order to estimate the effects of the addition of galvanic sludge on the finished product, the technical properties of the material were evaluated: loss by calcination, water absorption, linear shrinkage, three-point flexural strength, color, and spectroscopy characterization via IFTR, UV–Vis–NIR, and RAMAN, and ceramic-mount microstructure and crystal structure via XRD. The effectiveness of the ceramic for the retention of Cu, Ni and Cr was determined from the leaching test, in order to characterize the toxicity (TCLP) of the finished and ground samples according to EPA 1311. As a result, it was determined that the addition of sludge to the clay modified the color of the finished product, decreased the flexural strength, and increased the shrinkage and the total porosity. Therefore, the sintered product acted satisfactorily as an encapsulating agent.

Quantitative Assessment of Environmental Soil Functions in Volcanic Zones from Mexico Using S&E Software

Making quantitative evaluations of the environmental functions of the soil in a quantitative way is an urgent necessity for transitioning towards the sustainable use of soils. The objective of this work was to use and improve the Soil and Environment software for soils of volcanic areas, for which the software was not designed to work on. The study was conducted in the volcanic area of Michoacan, Mexico. Nine soil profiles were described; samples were taken from each horizon and the physical and chemical properties of each sample were analyzed. The Soil and Environment software was used to conduct pedoecological evaluations of the soil samples and, subsequently, an evaluation of the environmental functions of the soils and the modeling of scenarios was carried out. The soil profiles studied showed variable properties of hydraulic conductivity, field capacity, air capacity, effective cation exchange capacity, and soil organic carbon. The soils showed very high nutrient retention, high naturalness and sorption of heavy metals, and low cultural and natural archive properties. The Soil and Environment software generally works well with soils of volcanic areas; however, we suggest improvements in the evaluation method of the following functions: naturalness and agricultural quality. Additionally, the estimating method of aeration capacity and hydraulic conductivity should be calibrated for the properties of the volcanic soils. The modeling of scenarios allowed us to identify the soil profiles that are most vulnerable to degradation. The modeling of scenarios provided a clear idea of the negative and positive effects that a change in soil use would have.

Advanced SiO2 Composite Materials for Heavy Metal Removal from Wastewater

Thermal processing of materials is used in a very broad sense to cover all sets of technologies and processes for a wide range of industrial sectors and it refers to material development with a specific application potential due to its advantages over conventional synthesis methods. By applying hydrothermal technique, the development of advanced materials has been pursued, in order to retain heavy metals from wastewater. This research refers to nanosilica-based materials, specifically mesoporous silica, for which the heavy metal retention properties were improved by using nano-TiO2 and nano-CeO2, considering the properties of titanium and cerium. Advanced methods have been used to characterize the materials obtained as X-ray fluorescence (XRF) and energy-dispersive X-ray spectroscopy (EDS) for chemical composition; X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) for microstructural properties and BET analyser for pores and specific surface area characterization. The results showed higher retention efficiencies for the doped nanosilica.

Hydraulic performance and chemical compatibility of a powdered Na-bentonite geosynthetic clay liner permeated with mine drainage

The hydraulic and chemical compatibility of a geosynthetic clay liner (GCL), containing powdered Na-bentonite, was evaluated against artificial acid rock drainage (ARD) in terms of the swell index, hydraulic conductivity and heavy metal retention. Six artificial ARDs with an approximate pH of 3 and different metal concentrations (electrical conductivity, EC, ranging between 75 and 1000 mS/m; ionic strength ranging between 8 and 400 mM) were used in the experiments. The results of free swelling tests showed that high metal concentrations (EC higher than 70 mS/m) negatively impact the swell volume by lowering it. The hydraulic conductivity of the GCL permeated with distilled water was 1.2 × 10−11 m/s, falling in the range of 7.9 × 10−12 to 1.1 × 10−10 m/s when prehydrated with distilled water and permeated with ARDs. The ion exchange and metal precipitation appeared to be the main mechanisms controlling the metal attenuation on the bentonite. The ion exchange mechanism starts with the release of Na from the bentonite and the sorption of the bi- and tri-metals present in the ARDs onto the bentonite. After the depletion of Na, the ion exchange reaction proceeds with the desorption of Ca and Mg from the bentonite and the sorption of cations present in the ARDs onto the bentonite layers. The depletion of Na from the bentonite and the subsequent release of Ca and Mg correlate to the sudden drop in pH and a gradual increase or equilibration of the hydraulic conductivity. It is possible to say that, after this point, hydraulic and chemical equilibrium is reached. From the overall results, the tested GCL showed acceptably low hydraulic conductivity and the potential to attenuate heavy metals present in ARDs.

What do we know about actinides-proteins interactions?

Abstract Since the early 40s when the first research related to the development of the atomic bomb began for the Manhattan Project, actinides (An) and their association with the use of nuclear energy for civil applications, such as in the generation of electricity, have been a constant source of interest and fear. In 1962, the first Society of Toxicology (SOT), led by H. Hodge, was established at the University of Rochester (USA). It was commissioned as part of the Manhattan Project to assess the impact of nuclear weapons production on workers’ health. As a result of this initiative, the retention and excretion rates of radioactive heavy metals, their physiological impact in the event of acute exposure and their main biological targets were assessed. In this context, the scientific community began to focus on the role of proteins in the transportation and in vivo accumulation of An. The first studies focused on the identification of these proteins. Thereafter, the continuous development of physico-chemical characterization techniques has made it possible to go further and specify the modes of interaction with proteins from both a thermodynamic and structural point of view, as well as from the point of view of their biological activity. This article reviews the work performed in this area since the Manhattan Project. It is divided into three parts: first, the identification of the most affine proteins; second, the study of the affinity and structure of protein-An complexes; and third, the impact of actinide ligation on protein conformation and function.

Effect of natural geotextile on the cotransport of heavy metals (Cu2+, Pb2+, and Zn2+) and kaolinite particles

ABSTRACT A cotransport study of heavy metals and kaolinite particles in sand column with and without flax geotextiles was carried out. The objectives were to evaluate the potential role of kaolinite in heavy metals transfer and to analyse the influence of flax geotextiles on the transfer of these pollutants. The adsorption rates of heavy metals on the kaolinite particles were, respectively, 53%, 65% and 25% for copper, lead, and zinc. The injection of kaolinite with heavy metals resulted in a significant decrease in the retention efficiency of copper and lead in the filter. The presence of kaolinite in the injected solution has virtually no influence on the effectiveness of zinc fixation in the filter. The retention of heavy metals is in the order of Zn > Cu > Pb with a significant drop of retention efficiency of 34% for copper, 67% for lead, and less than 1% for zinc. The presence of kaolinite in the injected solution reversed the retention order of heavy metals when metals solution was injected alone. Flax geotextiles increase the ability of the filter to retain soluble and attached heavy metals. It improves the sand retention capacity and it retains soluble and attached metals in its structure.

Hydroxyapatite-Based Electrodes for Metal Detection in Wastewater

Hydroxyapatite (HAp) is a biocompatible versatile material of formula Ca10(PO4)6(OH)2, insoluble in water within a wide pH range, chemically stable, relatively cheap and largely available. This mineral calcium phosphate has caught attention of scientists working in different fields of applied science, from medical engineering [1], to catalysis [2] and pollution remediation [3],[4]. For environmental application, the absorbent nature of HAp is, probably, the most valuable feature. In particular, heavy metal retention ability is attributed to ion-exchange (Ca2+/ metal ion), surface adsorption/complexation, dissolution-precipitation mechanism, with single or combined action depending on the metal nature [5]. Combining intrinsic affinities of HAp for metals with ductility of electrochemistry is a valuable route to develop monitoring systems and/or pollution remediation protocols [6]. In doing so, the main obstacle for the exploitation of HAp as electrode materials is its electrical insulation nature. To overcome this limitation combination with conductive substrate is necessary, preparing either blends or composite materials. In this context, a series of carbon-containing hydroxyapatite composites (C-HAp) have been prepared by co-precipitation synthesis, by varying the conductive carbon source. The prepared materials have been characterized by various physical-chemical techniques (FT-IR spectroscopy, XRPD, TEM-EDX, N2-adsorption/desorption analyses) and the electrical conductivity has been determined as a function of the carbon source. The most promising C-HAp composites have been used as electrode substrates to quantify some of the common heavy metals found in waste water from urban and/or industrial sites (e.g., Pb2+, Cd2+, Cu2+, Zn2+) using cyclic and differential voltammetry techniques. The sensitivity of C-HAp electrodes was compared with that of glassy carbon ones, chosen as reference material. Different electrode geometries have been taken into consideration (C-HAp powder pressed into a cavity electrode, or free-standing C-HAp one). The work is still in progress and among possible alternative routes we are going to prepare directly HAp-based electrodes by in situ electrodeposition of calcium phosphate on low cost electron collectors such as steel. The final aim is to employ the HAp-based electrode as cathode in microbial fuel cells that could act as sensors for the on-line detection of metal traces in the treated wastes.

Investigating the Influence of the Leachate from the Municipal Solid Waste on the Mechanical and Environmental Properties of Soil around the Landfill (Case Study: The Municipal Landfill Located in Ardabil—Iran)

Leachate is a very hazardous liquid, and it is considered as one of the major concerns regarding landfills. Landfill leachate is the result of water penetration from solid waste and oxidation of waste and parcels. The undeveloped landfills allow the leachate to cross easily through the soil. This can affect the soil engineering properties such as shear strength, soil compressibility and chemical properties (absorption and retention of heavy metals). This research has investigated the influence of the leachate resulted from municipal solid waste in Ardabil with different percentages and densities on the parameters of shear strength and compressibility of the soil around the site. Also, a test, which is called leachate column test, was carried out to study the environmental properties of the soil (the rate of pollutant absorption and pollutants transmission). The results indicate that with increasing leachate percentage, the internal friction angle decreases. Moreover, soil cohesion is significantly reduced and the compressibility results indicate that soil compressibility will also increase. Increasing the concentration of leachate reduces the cohesion and increases the internal friction angle as well as the compressibility, and changes the volumetric pressure of the soil. Also, the results of leachate test, which shows the rate of pollutants absorption and transmission in the sample placed in the chamber, indicate that the concentration of nickel and zing goes up by increasing the volume of the passing leachate.

The impact of additives on the retention of heavy metals in the bottom ash during RDF incineration

Up to now, a few studies on the efficiency of heavy metal(-oid)s capture by a sorbent directly mixed with fuel, have been performed. For this reason, the main objective of the study is to determine whether or not such a solution is effective when RDF is incinerated. The paper presents a two-step analysis of the impact of three sorbents (ammonium sulphate, kaolinite and halloysite) in three dosages (2, 4 and 8 wt%) on heavy metal(-oid)s retention in the bottom ash. 12 heavy metal(-oid)s were taken into consideration - As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Sb, V and Zn. Samples were incinerated in a lab-scale tubular reactor at two temperatures - 900 °C and 1100 °C. The first step of investigation constitutes ICP analysis of heavy metal(-oid)s content in the bottom ash, coupled with SEM/EDS analysis. Afterwards, the second step was to determine the stability of formed additive-heavy metal(-oid)s complexes via leachability tests in neutral and acid environments. The performed research has shown that ammonium sulphate is effective in Cr, Cu and Hg capture, halloysite – in Cd, Co, V and Mn capture, whereas kaolinite – in Pb capture.

Rapid inversion of heavy metal concentration in karst grain producing areas based on hyperspectral bands associated with soil components

Heavy metal pollution in soil has become a prominent problem affecting agricultural security and ecological health. Hyperspectral remote sensing is used as a rapid method to predict soil heavy metal concentrations. The processing of spectral data and the variables of the estimated model has an important impact on the predictive model of soil heavy metal elements. In this paper, smoothed and resampled spectral reflections are preprocessed by using three preprocessing methods, namely, standard normal variate (SNV), multiplication scatter correlation (MSC) and normalization (NOR). Then, first and second order differential (FD and SD, respectively) and absorbance transformation (AT) are performed. Based on the adsorption and retention of heavy metals by various soil components, the relevant spectral bands are extracted as modeling variables. An extreme learning machine algorithm (ELM) is used to establish the model, and the effects of different factors on the model are compared. Results show that the combination of the three preprocessing methods (SNV, MSC and NOR) with spectral transformation can enhance the stability and predictive ability of the resulting model. The combination of SNV and FD can predict the contents of Cr, Ni and Pb. The R2 of the model is 0.85, 0.87 and 0.80 respectively. The optimal model of Cu is derived from the combination of NOR and SD (R2 = 0.84), and the spectral responses of soil Cr, Ni, Cu and Pb, are closely related to clay mineral-related and organic matter-related bands. The model established by the clay-related bands enhances the stability of the prediction of Ni content, and the RPD value was increased from 2.46 to 2.72 compared with the full-band model. The combination of bands associated with organic matter and clay minerals can accurately predict the content of Cr and Cu in soil; indeed, the predict model R2 for these elements reaches 0.88. Accurate prediction of soil Pb by the full-band model indicates that the Pb concentration in the study area is related to a various of soil chemical components. The prediction effects of the four heavy metal elements show the order Cr > Cu > Ni > Pb. The results of the current study complement the theoretical basis for estimating the heavy metal content of soil by hyperspectral spectroscopy, and provide important insights into the application of hyperspectral remote sensing to monitor other heavy metals.

Effect of supercritical carbonation on the strength and heavy metal retention of cement-solidified fly ash

This paper presents both experimental and multi-physics studies on the carbonation and heavy metal retention properties of cement-solidified fly ashes. Cement-solidified fly ash samples with 40% and 60% fly ash ratios were tested for carbonation depth after being supercritically carbonated. Tests were also carried out for compressive strength and retention capacity of heavy metals of the samples before and after supercritical carbonation. Using CO2 absorption instead of calcium carbonate to measure carbonation degree, a multi-physics model was developed and combined with a leaching model to study the impact of carbonation on Cu and Pb leaching from the cement-solidified fly ash. The results show that supercritical carbonation has both positive and negative impacts on the strength and retention capability of heavy metals of the cement-solidified fly ashes, which suggests that both the carbonation conditions and the amount of fly ash recycled in cementitious materials should be properly controlled to maximize potential positive effect.

Nonwoven flax fibres geotextiles effects on solute heavy metals transport in porous media

ABSTRACTFiltration tests were carried out in laboratory columns filled with crushed sand with and without flax geotextiles to study the transfer and retention of soluble heavy metals. Divalent cations of copper, zinc and lead were simultaneously and continuously injected in filtration columns. Results show that, when geotextiles discs are present the retention of metals in sand is favoured and retention profiles are modified. In addition, and unlike synthetic geotextiles, flax fibres geotextiles contribute to the retention of a significant fraction of the cationic metal pollutants in their own structure. The overall metals retention efficiency of the filter is improved. Competition between cationic metals for adsorption on retention sites occurs in the column in the order Pb > Cu > Zn. Most of the lead is retained in the inlet of the column while copper and even more zinc migrate deeper in the column.

Performance comparison of macromolecular assisted and immobilized low pressure membranes in the removal of toxic metals

The removal of toxic heavy metals (Cd, Pb and Hg) from aqueous solution has been attempted in two different modes by using macromolecular assisted and immobilized multilayered modified polyether sulfone membranes (PES). PES membrane was modified with chitosan (CHI) and poly (styrene sulfonate) (PSS) using layer by layer (LbL) method. Humic acid (HA) and cholesterol (CHO) were used for immobilization. SEM and AFM confirmed that the obtained films were rough and highly porous. FTIR analysis confirmed successful immobilization of macromolecules in poly-ion coated membranes. Ellipsometric studies confirmed that the thickness of system increased with immobilization. Thermogravimetric analysis proved that the membranes were thermally stable upto 550 °C. The macromolecule assisted low pressure filtration was carried out by the addition of HA and CHO to the respective spiked metal ion solutions prior to filtration. More than 98% of the heavy metal ions were retained by macromolecules immobilized membranes. For Cd2+ ions, rejection efficiency of 6 bilayered PES membrane achieved ∼90% with HA and CHO immobilized at a concentration of 20 μmol/L and 400 μmol/L respectively. For Pb2+ ions, rejection efficiency attained ∼90% for HA (2 bilayered system) and for CHO (4 bilayered system) immobilized at 15 μmol/L and 400 μmol/L respectively. The rejection efficiency for Hg2+ ions obtained above 95% for both HA and CHO immobilized membranes at 2 bilayer with concentrations 15 μmol/L and 300 μmol/L respectively. The macromolecule assisted filtration also showed very good removal for all metal ions with efficiency above ∼90%. High macromolecule concentration with high number of bilayers has resulted high flux with negligible effect on the retention of heavy metals. Thus, this membrane system provides a very simple, efficient, easy and convenient approach for the removal of toxic metal ions by employing a combination of poly-ion coated polymer membrane with macromolecules.

The role of limestone and dolomite tailings’ particle size in retention of heavy metals from liquid waste

The present study did not originate under any of project and no funding was raised for research. However, we would like to thank especially Professor Angeliki Moutsatsou and the personal of the Laboratory of Inorganic and Analytical Chemistry of the Chemical Engineering School in the National Technical University of Athens for their various support during the experimental work required for the successful realization of the present study.

Analysis of the adsorption and retention models for Cd, Cr, Cu, Ni, Pb, and Zn through neural networks: selection of variables and competitive model.

In this study, the neural networks are used to predict and explain the behavior of different edaphological variables in the adsorption and retention of heavy metals, both isolated and competing. A comparison with the results obtained using multiple regression, stepwise analysis, and regression trees is performed. In the neural network technique, CEC amorphous and crystallized oxides and kaolinite in the clay fraction are the most selected variables for making the optimal models, while mica and, to a lesser extent, plagioclase, are the next variables selected. Additionally, a competitive model has been considered, using simultaneously different metals. In the competitive model, the model predicts a more intense competence between Pb and Ni for the adsorption process and between Cr and Ni for the retention process.

Arbuscular mycorrhizal fungi enhance antioxidant defense in the leaves and the retention of heavy metals in the roots of maize.

In this study, we investigated the effects of the arbuscular mycorrhizal fungi (AMF) Funneliformis mosseae and Diversispora spurcum on the growth, antioxidant physiology, and uptake of phosphorus (P), sulfur (S), lead (Pb), zinc (Zn), cadmium (Cd), and arsenic (As) by maize (Zea mays L.) grown in heavy metal-polluted soils though a potted plant experiment. F. mosseae significantly increased the plant chlorophyll a content, height, and biomass; decreased the H2O2 and malondialdehyde (MDA) contents; and enhanced the superoxide dismutase (SOD) and catalase (CAT) activities and the total antioxidant capacity (T-AOC) in maize leaves; this effect was not observed with D. spurcum. Both F. mosseae and D. spurcum promoted the retention of heavy metals in roots and increased the uptake of Pb, Zn, Cd, and As, and both fungi restricted heavy metal transfer, resulting in decreased Pb, Zn, and Cd contents in shoots. Therefore, the fungi reduced the translocation factors for heavy metal content (TF) and uptake (TF') in maize. Additionally, F. mosseae promoted P and S uptake by shoots, and D. spurcum increased P and S uptake by roots. Moreover, highly significant negative correlations were found between antioxidant capacity and the H2O2, MDA, and heavy metal contents, and there was a positive correlation with the biomass of maize leaves. These results suggested that AMF alleviated plant toxicity and that this effect was closely related to antioxidant activation in the maize leaves and increased retention of heavy metals in the roots.

Potential ecosystem service values of mangrove forests in southeastern China using high-resolution satellite data

Mangrove forests provide a large number of important ecological, economic, and social benefits. This study proposes a pixel-based method for estimating the spatial variability of mangrove ecosystem services (coastal protection, carbon sequestration, nutrient retention and heavy metal retention) in the Jiulong River Estuary using a combination of high-resolution satellite data with market price and replacement cost approaches. The results indicated that there was a considerable variability in the ecosystem service values caused by the distance of mangroves to the coast and the different growth phases of mangrove forests. The total estimated value of the four selected ecosystem services was US$ 287,993/year for 174.58 ha (approximately US$ 1650/ha/year). Coastal protection was estimated to provide the highest value (US$ 239,683/year), amounting to 83.23% of the total value of the ecosystem services, followed by nutrient retention (US$ 25,283/year), contributing 8.78% of the total value of the ecosystem services and accounting for up to 52.33% of the total value of regulating services. Heavy metals retention (US$ 10,289/year) and carbon sequestration (US$ 12,738 in 2015/year) had relatively low values in comparison to those of coastal protection and nutrient retention. However, there was an underestimation of mangrove ecosystem services because we did not consider other services, such as fisheries, biodiversity, recreation, education and tourism, mainly due to the lack of primary data. Nevertheless, the estimated economic value of mangrove ecosystem services in this area is meaningful to raise awareness of the benefits provided by mangroves to local communities and policy makers.

Accumulation of Heavy Metals in Roadside Soil in Urban Area and the Related Impacting Factors.

Heavy metal contamination in roadside soil due to traffic emission has been recognized for a long time. However, seldom has been reported regarding identification of critical factors influencing the accumulation of heavy metals in urban roadside soils due to the frequent disturbances such as the repair of damaged roads and green belt maintanance. Heavy metals in the roadside soils of 45 roads in Xihu district, Hangzhou city were investigated. Results suggested the accumulation of Cu, Pb, Cd, Cr, and Zn in roadside soil was affected by human activity. However, only two sites had Pb and Zn excessing the standards for residential areas, respectively, according to Chinese Environmental Quality Standards for soils. The concentrations of Cu, Pb, Cd, and Zn were significantly and positively correlated to soil pH and organic matter. An insignificant correlation between the age of the roads or vegetation cover types and the concentration of heavy metals was found although they were reported closely relating to the accumulation of heavy metals in roadside soils of highways. The highest Pb, Cd, and Cr taking place in sites with heavy traffic and significant differences in the concentrations of Cu, Pb, Cd, and Zn among the different categories of roads suggested the contribution of traffic intensity. However, it was difficult to establish a quantitative relationship between traffic intensity and the concentrations of heavy metals in the roadside soil. It could be concluded that impaction of traffic emission on the accumulation of heavy metals in roadside soils in urban area was slight and soil properties such as pH and organic matters were critical factors influencing the retention of heavy metals in soils.

Effect of mineral reaction between calcium and aluminosilicate on heavy metal behavior during sludge incineration

Calcium-based additives such as lime, portlandite and limestone are widely applied in solid waste incineration for desulfurization. However, calcium may affect emission of heavy metals. In this study, effects of mineral reaction on the transference of copper and zinc during sludge combustion are investigated. Sludge from a chemical fiber factory was blended with lime as an additive in different mass fractions. The incineration tests were performed in a tube furnace at temperatures of 600–1100 °C. Then the ash was digested into two methods to clarify two retention forms of heavy metals. The X-ray diffraction shows that the calcium from additive converted to calcite, amorphous calcium, gehlenite and anorthite successively as temperature rising. The two-step digestion reveals that minerals above change the distribution of heavy metals between different forms. The residual form of both two heavy metals increases with temperature upgraded, while the leachable form presents an opposite trend. Calcium stimulated the volatility of copper at all temperatures but took positive effect on volatility of zinc only at 600 °C and promoted its retention at higher temperatures. With consideration of retention forms, mineral composition and temperature, it is suggested that through reactions with aluminosilicate, calcium changes heavy metals transference to a different extent. Competition by calcium to produce aluminosilicate inhibits retention of heavy metals, but zinc can be together with calcium as eutectic aluminosilicate at higher temperatures. Surface morphologies were detected by scanning electronic microscopy and energy dispersive spectrometer, confirming the effect of calcium.

Predicting nickel concentration in soil using reflectance spectroscopy associated with organic matter and clay minerals

Heavy metal contamination in soil has become a serious environmental problem. Visible and near-infrared reflectance spectroscopy (VNIRS) is recognized as an alternative to rapidly predict heavy metal concentration in soil. The correlation between soil spectrally active constituents and heavy metals provides a mechanism for the prediction. Generally, the entire VNIR spectral region (VNIR-SR) without discrimination is used. Considering the adsorption and retention of heavy metals on soil spectrally active constituents, a method was proposed to predict heavy metal concentration in soil using VNIRS. Organic matter and clay minerals have strong sorption and retention for Ni in soil. Therefore, the spectral bands associated with organic matter and clay minerals were used to predict nickel (Ni) concentration to validate the proposed method. In this study, two sets of reflectance spectra of soil samples collected in Chenzhou and Hengyang, Hunan Province, China were used. The prediction model was calibrated with a combination of genetic algorithm and partial least squares regression (GA-PLSR). In Chenzhou, the ratio of prediction to deviation (RPD) and the coefficient of determination (R2) were improved from 1.566 and 0.577 to 2.139 and 0.773 by the prediction using the spectral bands associated with organic matter and clay minerals compared with the prediction using the entire VNIR-SR. The RPD and R2 were improved from 1.805 and 0.672 to 3.144 and 0.892 by the proposed method in Hengyang. To further validate the proposed method, the soil samples from Chenzhou were reallocated to calibration and validation sets according to Ni concentration. The RPD and R2 were improved from 1.193 and 0.267 to 2.396 and 0.818 by using the spectral bands associated with organic matter and clay minerals. The results indicate that the proposed method is effective in predicting Ni concentration and has the potential to predict other heavy metals in soil.