Fractionation Of Metals In Soils Research Articles

Fractionation of metals in soil for strawberry cultivation: Effect on metal migration in food chain and application in risk assessment

Although trace metals in strawberry production system have attracted growing attention, little is known about metal fractionation in soil for strawberry cultivation. We hypothesized that the metal fractions in soil influenced by strawberry production had significant effect on food chain transport of metals and their risk in soil. Here, samples of strawberries and soil were gathered in the Yangtze River Delta, China to verify the hypothesis. Results showed that the acid-soluble Cr, Cd, and Ni in soil for strawberry cultivation were 21.5%–88.3% higher than those in open field soil, which enhanced uptake and bioaccessible levels of these metals in strawberries. Overall, the ecological, mobility, and health risks of Pb, Zn, Ni, and Cu in soil were at a low level. However, the ecological risk of bioavailable Cd, mobility risk of Cd, and cancer risk of bioavailable Cr in over 70% of the soil samples were at moderate, high, and acceptable levels, respectively. Since the increased acid-soluble Cr and Ni in soil were related to soil acidification induced by strawberry production, nitrogen fertilizer application should be optimized to prevent soil acidification and reduce transfer of Cr and Ni. Additionally, as Cd and organic matter accumulated in soil, the acid-soluble Cd and the ecological and mobility risks of Cd in soil were enhanced. To decrease transfer and risk of Cd in soil, organic fertilizer application should be optimized to mitigate Cd accumulation, alter organic matter composition, and subsequently promote the transformation of bioavailable Cd into residual Cd in soil.

Research on the Transformation Mechanism of Soil Cadmium Fractions under the Conditions of Freeze-thaw and Crude Oil Contamination in Wetlands in the Songnen Plain, China

Environmental changes can significantly affect heavy metals behave in soil. Currently, we know little about the impact of crude oil contamination on heavy metal fractions in soil, with few studies available on heavy metal fraction transformation under the composite action of freeze-thaw and crude oil contamination. In this study, soil samples were collected from the Momoge Wetland in the Songnen Plain. Properties including pH, cation exchange capacity, calcium carbonate, free iron oxide, dissolved organic carbon, microbial biomass carbon, and cadmium (Cd) fractions under freeze-thaw, crude oil contamination, and the two combined (composite action) were analysed. The results show that under freeze-thaw, crude oil contamination, and composite action, soil properties changed significantly; soil water-soluble Cd content significantly increased by 54.17%, 62.50%, and 33.33% from control levels, respectively; soil ion-exchangeable Cd content decreased significantly by 10.90%, 23.73%, and 18.64% from control levels, respectively; soil residual Cd content significantly increased by 80.36%, 94.64%, and 132.14% from control levels, respectively; carbonate-bound, humic acid-bound, Fe-Mn oxide-bound, and strongly organic-bound Cd did not change significantly. Soil dissolved organic carbon, pH, CaCO3, and free iron oxide were significantly correlated with water-soluble, ion-exchangeable, carbonate-bound, and Fe-Mn oxide-bound Cd, respectively. This study provides a theoretical basis for evaluating soil Cd behaves in crude oil contaminated wetlands in cold regions.

Effect of biochar, zeolite and bentonite on physiological and biochemical parameters and lead and zinc uptake by maize (Zea mays L.) plants grown in contaminated soil

Heavy metals (HMs) are common contaminants with major concern of severe environmental and health problems. This study evaluated the effects of organo-mineral amendments (mesquite biochar (MB), zeolite (ZL) and bentonite (BN) alone and in combination) applied at different rates to promote the maize (Zea mays L.) growth by providing essential nutrient and improving the soil physio-chemical properties under zinc (Zn) and lead (Pb) contamination. Result revealed that the incorporation of organo-mineral amendments had significantly alleviated Pb and Zn contamination by maize plants and improved the physiological and biochemical attributes of plants. Combined application of organo-mineral amendments including BMA-1, BMA-2 and BMA-3 performed excellently in terms of reducing Pb and Zn concentrations in both leaves (19–60%, 43–75%, respectively) and roots (24–59%, 42–68%, respectively) of maize. The amendments decreased the extractable, reducible, oxidisable and residual fractions of metals in soil and significantly reduced the soil DTPA-extractable Pb and Zn. BMA-1 substantially improved antioxidant enzyme activities in metal-stressed plants. This study indicated that combined use of organo-mineral amendments can effectively reduce the bioavailability and mobility of Pb and Zn in co-contaminated soils. Combined application of organo-mineral amendments could be viable remediation technology for immobilization and metal uptake by plants in polluted soils.

Responses of soil microarthropods to soil metal fractions under different mediterranean vegetation covers

Soil microarthropods play essential roles in soil functioning and they are considered useful indicators of soil metal contamination, as they quickly respond to environmental changes. The toxicity of metals depends on their fractions, but few studies have been conducted on the responses of microarthropods to different metal fractions. The study aimed to assess the response of the soil microarthropods to the soil metal fractions (exchangeable: available for organisms, reducible: associated to Fe-Mn oxides, oxidizable: associated to organic matter) under different Mediterranean vegetation covers. To reach the aim, the soils of different vegetation covers (holm oak, pine, black locust and herbs) were analysed for pH, water content, total C, N and P and Corg, NH4+ and Passimilable contents, the exchangeable (F1), reducible (F2) and oxidizable (F3) fractions of Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, V and Zn and the microarthropod taxonomic and functional indices. The results showed that, regardless the vegetation cover, the F2 and F3 of Ca, Cr, Cu, Fe, K, Mg, Mn, V and Zn significantly inhibited the density of microarthropods, favouring the functional traits typical of disturbed environments. The element F1, except for Mn, slightly impacted on the microarthropod community. In addition, the soils under trees positively influenced the taxonomic and functional indices of the microarthropod community where higher contents of Corg and macronutrients were observed. Several taxa were differently impacted by three metal fractions of Al, Ca, Fe and K; in particular, Formicidae were favoured, whereas Diplopoda and Isopoda were favoured by Ca, Fe and K and inhibited by Al concentrations. The present research demonstrated that stable fractions (F2 and F3) of metals, instead to available one, exert a strong impact of microarthropod community. This leaded to change in microarthropod community assemblage, favouring taxa and traits typical of disturbed environments.

An Assessment of the Feasibility of Phytoextraction for the Stripping of Bioavailable Metals from Contaminated Soils.

Phytoextraction has been proposed in many papers as a low-cost method for remediating contaminated soil. However, if national regulation is based on total metal(loid) concentrations in soil, phytoextraction is generally infeasible because of the long time required for remediation. Assessing phytoextraction requires determination of the dynamic rate of metal removal from soil. Phytoextraction may be feasible if the main goal is to reduce the soluble fraction of the metal(loid) with the goal of reducing bioavailability. However, it has been reported that there is a large mass balance mismatch between the reduction of the soluble metal fraction in contaminated soil and metal uptake by plants. Several studies report that the decrease of soluble fraction of metals in soil is higher than can be accounted for by plant uptake. In other words, studies generally overestimate the feasibility of bioavailable contaminant stripping. Therefore, a more rigorous approach is advisable to ensure that papers on bioavailable contaminant stripping include relevant information on mass balances. Furthermore, to implement the concept of bioavailable contaminant stripping, regulations must distinguish between the bioavailable fraction and the total metal concentration in soil. Environ Toxicol Chem 2023;42:558-565. © 2022 SETAC.

Soil heterogeneity influence on the distribution of heavy metals in soil during acid rain infiltration: Experimental and numerical modeling

Acid rain is a global environmental problem that mobilizes heavy metals in soils, while the distribution and geochemical fraction of heavy metals during acid rain infiltration in heterogeneous soils are still unclear. In this study, we performed column experiments to investigate the distribution and geochemical fraction of Cu, Pb, Ni and Cd in heterogeneously layered soils during continuous acid rain infiltration. Chloride ion used as a conservative tracer was found to be uniformly distributed during acid rain infiltration, showing insignificant preferential flow effects in the column. In contrast, however, the distribution of heavy metals was highly non-uniform, especially in the silty soil at the lower part of the column, indicating a heterogeneous distribution of adsorption capacity. In addition, in the control experiments with neutral rain infiltration, uniform distribution of heavy metals was observed, indicating that the heterogeneous distribution of adsorption coefficient during acid rain infiltration was mainly caused by different pH buffering capacities. A numerical model considering water flow and solute transport was developed, where the average water-solid distribution coefficient (Kd) in Layer 2 was only 1.5–12.5% of that in Layer 1 during acid rain infiltration. The model could predict the variation of heavy metal concentrations in soil with the majority of error less than 35%, confirming that different Kd induced the heterogeneous distribution of heavy metals. In addition, the geochemical fraction of heavy metals in the upper coarse sand layer remained stable, while the acid-extractable fractions in the lower loam and silt loam layer gradually increased. Our findings suggest that soil heterogeneity, especially chemical heterogeneity affected by rainfall acidity, has an important influence on the infiltration, migration and geochemical fraction of heavy metals in soils. This study could help guide the risk assessment of heavy metal-contaminated sites that were polluted by acid rain or landfill leachate.

Probability of Health Risk, Bioaccumulation, and Geochemical Fractions of Toxic Elements in Soils and Vegetables Impacted by Manures in Nigeria

The intensive application of manures for the improvement of plant yield is a global practice by farmers notwithstanding the associated negative effects. The probability of health risk, bioaccumulation, and speciation of arsenic (As), cadmium (Cd), nickel (Ni), and lead (Pb) in soils and vegetables (Talinum triangulare and Telfairia occidentalis) impacted by untreated wastes from animal farms and inorganic fertilizers used as manures in the oil producing section of Nigeria were investigated. The total metal was determined using spectrophotometric methods while its geochemical fractions were identified following the modified Community Bureau of Reference (BCR) procedures of sequential extraction. The results obtained indicated the following mean concentrations (mg kg-1): 1.64 ± 0.70, 3.17 ± 1.47, 62.22 ± 8.83, and 187 ± 29.73 for As, Cd, Ni, and Pb, respectively. The results revealed that the mean concentrations of all the metals in the studied locations, except As, were above their recommended limits by the Food and Agricultural Organization/World Health Organization (FAO/WHO). The mean values of As and Pb in T. triangulareand T. occidentalis were also above the acceptable limits. Relatively higher levels of the metals were recorded at the studied locations as compared to the control site. The transfer factors of metals determined were generally lower than one; hence, the human exposure rate to these metals may not be high. The sequential extractions of metal indicated that As and Pb existed in the reducible fraction, Cd in the acid extractable fraction, and Ni in the residual fraction. The contamination factor of the metals revealed that As and Ni belong to the low contamination class, while Cd and Pb fall within the very high contamination category. The study showed that all the studied locations were heavily contaminated, with Uyo being the most polluted site. The principal component analysis identified anthropogenic factor as the main contributor to the presence of these metals in the investigated area. Daily intake rates for these metals via vegetable consumption by both the elderly and young populations were generally lower than their recommended oral reference doses. The non-carcinogenic risks obtained for both populations were less than one. However, the consumers of T. triangulare and T. occidentalis from the studied locations were exposed to Pb toxicity, with children being more vulnerable. This study has shown that the application of untreated animal wastes and inorganic fertilizers as manures has the potential to affect human health, bioavailability of metals, and the geochemical fractions of metals in soil over time.

Response of microbiomes with different abundances to removal of metal fractions by soil washing

Toxic metal contamination causes a great threat to soil ecosystem and human health. Soil washing is a fast practice for removing metals, but its influences on microbial diversity and the stability of soil ecosystem remain unknown. In this study, ethylenediaminetetraacetic acid (EDTA), citric acid (CA), and fermented pineapple peel residue (FPP) were used as representatives of chelates, low molecular organic acids and biological materials to wash Pb-polluted soils, and their impacts on microbial community were investigated. Washing with these agents effectively removed Pb, but altered microbial community structure. After washing with EDTA, CA, and FPP, 3–8 bacterial phyla and 1 fungal phylum greatly increased, while 7–20 bacterial and 0–6 fungal phyla severely decreased or even disappeared. The alterations of different microbiomes were closely related to soil metal fractions. The labile metal fraction had negative effects on most bacteria and fungi, but also showed positive influences on Actinobacteria, Patescibacteria, and Fusobacteria. The moderately stable and stable fractions were nontoxic to the most microbes, but still harmful to Patescibacteria and Deinococcus-Thermus. These findings provide new insights for the effects of soil washing remediation and toxicity of metal fractions on the microbiomes with different abundance.

Chemical fractionation of some heavy metals in soils irrigated from El-Saff wastewater drainage canal, Egypt

ABSTRACT Assessment of heavy metals fractions in soils irrigated with wastewater can directly reflect their bioavailability and contamination level in soil depths. The present study was conducted to assess the heavy metals (Cd, Cu, Pb, Mn, and Fe) fractionation in agricultural soils illegally irrigated with El-Saff wastewater drain, southern Giza Governorate, Egypt. Generally, practices of wastewater irrigation increased pH values in the deeper depths of irrigated soils. Results revealed that long-term wastewater irrigation profoundly affected the studied heavy metals fractions in soil depths. Generally, the ranges of studied heavy metals concentrations in soils irrigated with wastewater were apparently different. All fractions were significantly higher in the upper soil depths (0–60 cm and 30–60 cm) than the deeper depths. (60–90 cm and 90–120 cm). Heavy metals concentrations varied in the soils as Fe > Mn > Cu > Pb > Cd after irrigation. The heavy metals fractions were dominant in the residual form followed by oxides bound and organically bound fractions. Lower contents of heavy metals in the soil were obtained in the exchangeable fraction. Wastewater irrigation resulted in the transformation of heavy metals into different fractions as residual > oxide associated > organically bound > carbonate associated > exchangeable form. Monitoring of heavy metals concentration in El-Saff wastewater effluent is periodically required.

Effect of Combined Soil Amendment on Immobilization of Bioavailable As and Pb in Paddy Soil.

Heavy metal pollution in soil can have detrimental effects on soil ecosystems and human health. In situ remediation techniques are widely used to reduce the bioavailable fractions of heavy metals in soil. The main objective of this study was to examine the reduction of the bioavailable fractions of As and Pb in paddy soil with artificial lightweight material (ALM) manufactured from recycled materials. A total of four treatments, including a control (no amendment), ALM10 (10% of ALM in soil), ALM10+L (10% ALM combined with 0.5% lime), and ALM10+FeO (10% ALM combined with 0.5% FeO), were applied to paddy fields, and rice (Oryza sativa L.) was cultivated after 32 weeks. The highest reduction efficiencies for the bioavailable fractions of As and Pb in soil were observed in the ALM10+FeO (52.8%) and ALM10+L treatments (65.7%), respectively. The uptake of As decreased by 52.1% when ALM10+FeO was applied to paddy soil, and that of Pb decreased by 79.7% when ALM10+L was applied. Correlation analysis between bioavailable heavy metals in soil and soil chemical properties showed that soil pH, electrical conductivity (EC), P2O5, and soil organic matter (SOM) were the main factors controlling the mobility and bioavailability of As and Pb. Overall, the efficiencies of As and Pb reduction increased synergistically in both soil and plants when FeO and lime were combined with the ALM. In future studies, long-term monitoring is necessary to examine the longevity of soil amendments.

Cd and Zn Concentrations in Soil and Silage Maize following the Addition of P Fertilizer

Studies of soil Cd and Zn are often performed on sites that are contaminated or have deficient Zn conditions. Soil characteristics and crop management could impact the soil mobility and uptake of Cd and Zn, even when considering unpolluted Cd soils and adequate soil Zn levels. The concentrations of these two metals were assessed in soil and silage maize under five P fertilization treatments at two growth stages under low Cd and sufficient Zn conditions. Pearson correlation coefficients and stepwise linear regressions were calculated to investigate the soil characteristics influencing the bioavailable metal fraction in soil and the metal concentration in silage maize. P treatments did not impact Cd accumulation in maize; however, the Zn uptake was affected by P placement at the leaf development stage. From early development to maturity, the Cd level in maize decreased to 10% of the initial uptake, while the Zn level decreased to 50% of the initial uptake. This reduction in both metals may be attributed to a dilution effect derived from high biomass production. Silage maize could alleviate the initial Cd uptake while diminishing the depressant effect of P fertilizer on Zn concentration. Further research is required to understand the effect of P fertilizer on Cd uptake and its relation to Zn under field conditions at early and mature stages.

EFFECT OF SOIL IRRIGATION WITH WASTEWATER ON NI FRACTIONS IN SOME CONTAMINATED SOILS IN EGYPT

In this study Ni species were determined using a sequential extraction technique. The method consists of sequential extraction of the soil with different solutions, and it is designed to separate into six operationally defined fractions namely water soluble, exchangeable, carbonate bound, Fe-Mn oxides bound, organic bound and residual fractions. The objectives of this study were to investigate nickel forms in tested soils and to determine the effect of industrial wastewater effluent irrigation on the metal fractions in soil. Data showed a remarkable increase in all tested Ni-forms in polluted soil. It could be concluded that soil composition has been changed with depth. Especially under such condition whereas, metal soluble organic compounds found in wastewater may precipitate and percolates through soil and may transport soluble Ni with the soil solution.

Fractionation of heavy metals in soils cultivated with tobacco in Pinar del Río, Cuba

Knowledge of the presence of heavy metals in soils of agricultural areas is important to prevent their accumulation in cultivated plants. The objective of the present investigation was to evaluate the total concentrations and fractions of heavy metals Cd, Pb, Zn, Fe, Mn, Ni, Cu, Cr and Co in the tobacco-growing area of Pinar del Río, Cuba and their relationship with the physicochemical properties of soil. For the study, 59 samples of three types of soils were collected at 20 cm depth. The pseudo-total concentrations of metals in the soils are low and lower than the prevention values registered for Cuban soils. In general, the heavy metals studied present a high affinity for the most stable fractions of the soil, which means a low risk of transfer to the tobacco crop or accumulation in groundwater. The pseudo-total concentrations of heavy metals were low, below the alert values established for soils in the region. The heavy metals studied were mainly associated with the residual fraction, the second fraction with the highest association with metals was that linked to manganese and iron oxides. The principal component analysis showed that their main source is pedogenetic and that these elements are closely related to cation exchange capacity and calcium content.

Biochemical Responses of Medicinal Plant Tussilago farfara L. to Elevated Heavy Metal Concentrations in Soils of Urban Areas.

This study was conducted in Tyumen (Russian Federation) to establish the effects of heavy metals’ (Cu, Zn, Fe, Mn, Pb, and Cd) accumulation in soil and coltsfoot, as well as plants’ biochemical responses to such an accumulation. The mobile and acid-soluble heavy metal fractions in soils, and the heavy metal contents in plants, were determined by atomic absorption spectrophotometry. The Cu, Zn, Fe, Mn, and Pb concentrations in soils exceeded background values. Pb content at the battery manufacturing plant was above the maximum permitted concentration. The percentages of the mobile heavy metal fractions decreased in the following order: Mn > Zn > Cu > Fe. The greatest heavy metal accumulation in soils and plants was found at the battery manufacturing and metallurgical plants examined in our study. Heavy metals’ accumulation in the aboveground part of Tussilago farfara decreased in the following order: Fe > Zn > Cu > Mn > Pb > Cd. The accumulation of heavy metals stimulated the synthesis of photosynthetic pigments by 6–30%. Heavy metals provoked oxidative stress in cells, increasing the concentration of lipid peroxidation in products by up to 80%. Plant phenolics and flavonoids in the urban area of our study decreased compared to those in the control by 1.05, reaching up to 6.5 times. The change in coltsfoot catalase activity both increased and declined. Biochemical responses and heavy metal accumulation in coltsfoot from urban areas limit its use for medicinal purposes.

Efficiency of CH4N2S−modified biochar derived from potato peel on the adsorption and fractionation of cadmium, zinc and copper in contaminated acidic soil

The objective of this study was to investigate the characteristics of potato peel biochar (PPB) and modified potato peel biochar (MPPB), and their effects on the adsorption and fractionation of some heavy metals in contaminated acidic soil. The results showed that the modified potato peel biochar has a higher pH, cation exchange capacity (CEC), surface functional groups, oxygen/carbon (O/C), and hydrogen/carbon (H/C) ratios than the PPB. The addition of modified biochar to soil, especially at the application rate of 8 %, increased soil pH, CEC, and organic carbon (OC). The maximum adsorption capacity values of Cd, Zn, and Cu in the soil amended with MPPB at the application rate of 8 % were 5142.63, 3508.44, and 4993.12 mg kg−1, respectively. The addition of MPPB to the soil transformed the unstable fraction (soluble and exchangeable) of heavy metals to stable fractions (Fe/Mn oxides–bound, organically–bound, and residual). Compared to the control treatment, the soluble and exchangeable fraction of Cd, Zn, and Cu in soil amended with 8 % MPPB decreased to 102.97, 94.4, and 76.18 mg kg−1, respectively. The order of increment of organically–bound and residual fractions of heavy metals in soil amended with 8 % MPPB were Cu > Cd > Zn and Cd > Cu > Zn, respectively. The results of this study showed that MPPB can be used as a low-cost and eco-friendly adsorbent for the immobilization of heavy metals in contaminated acidic soils.

Impact of ancient iron smelting wastes on current soils: Legacy contamination, environmental availability and fractionation of metals

Past and present metallurgical activity is the origin of the metallic contamination of some current soils. The purpose of this research is to assess the environmental risk of ancient Fe smelting wastes to the terrestrial compartment. For this purpose, two study sites were investigated in Bourgogne-Franche Comté (France). For each site, the soil contamination (Co, Cu, Fe, Mn, Ni and Zn) and the mobility of each metal from the slag to the topsoils were assessed. The principal results show that the topsoils are particularly enriched in Fe and Mn compared to the reference soils. The bulk chemistry of the slag showed high Fe and Mn content related to the mineralogy of slags, in which the minerals include fayalite, spinel, wustite and glass. In the topsoils, we also observed newly formed minerals (clay minerals, goethite and hematite), which were absent in the reference soils. The presence of slag microfragments in soils and the partial weathering of slags, which contributed to the release of metals in the soils, can explain the contribution of slags to the current contamination of soils. The extensive study of a depth profile from Puisaye showed a low vertical diffusion of the released metal in the heap substratum. We also investigated the fractionation of metals in soils and their environmental availability. The results showed that Mn is generally present in reducible forms or associated with the residual fraction but is less adsorbed to the organic matter (OM) or present in easily exchangeable forms. In contrast, the low extractability of Fe indicates that it is mostly bound to the residual (i.e., mineral) fraction. Based on the easily exchangeable metal concentrations measured in soils, low to medium ecological risks were identified at the sites investigated.

Stabilisation of heavy metals in soil using nanoscale zero-valent iron coated with palygorskite

ABSTRACT The nanoscale zero-valent iron (nZVI) coated with palygorskite (PAL) was synthesised and used to remediate the soil contaminated by heavy metals. X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicated that a large number of nanoscale particles (had a grain size of 40–60 nm approximately) were distributed on the surface or pores of PAL homogeneously. The CaCl2 extraction and TCLP test were carried out to evaluate the bioavailability and mobility of four metals in soil amended by PAL-nZVI. The loading mass ratio of 2:1 between PAL and nZVI showed the optimised effect during the heavy metals’ stabilisation. BCR sequential extraction was employed to measure the change of metal fractions in soil. The residual fraction concentration increased significantly, indicating that the fraction of heavy metals tended to stabilise after amended with PAL-nZVI. The result of pot experience showed that the corn’s biomass increased, and the uptake of heavy metals was reduced significantly, which suggested the PAL-nZVI could stimulate the growth of corn by increasing the stabilisation of heavy metals in soil. Thus, PAL-nZVI as a novel and high-efficiency amendment could be applied to remediate the heavy metals-contaminated soil.

Do soil amendments used to improve agricultural productivity have consequences for soils contaminated with heavy metals?

This study presents an analysis of the effects of manure and lime commonly used to improve agricultural productivity and evaluates the potential for such soil amendments to mobilise/immobilise metal fractions in soils contaminated from nearby mine tailings in the Zambian Copperbelt. Lime and manure were applied at the onset of the study, and their effects were studied over two planting seasons, i.e. 2016-17 and 2017–18. Operationally defined plant-available Cd, Cu, Ni, Pb and Zn in the soil, were determined by extraction with DTPA-TEA (diethylenetriaminepentaacetic acid-triethanolamine) and 0.01 M Ca(NO3)2, before, and after, applying the amendments. In unamended soils, Cd was the most available and Ni the least. Lime application decreased extractable Cd, Cu, Ni, Pb and Zn. The response to lime was greater in soils with an initially acidic pH than in those with approximately neutral pH values. Manure increased DTPA extractable Zn, but decreased DTPA and Ca(NO3)2 extractable Cd, Cu and Pb. Combined lime and manure amendment exhibited a greater reduction in DTPA extractable Cd, Ni, Pb, Zn, as well as for Ca(NO3)2 extractable Cd compared to separate applications of lime and manure. The amendments had a significant residual effect on most of the soil fractions between season 1 and 2. The results obtained in this study showed that soil amendment with minimal lime and manure whilst benefiting agricultural productivity, may significantly reduce the mobility or plant availability of metals from contaminated agricultural soils. This is important in contaminated, typical tropical soils used for crop production by resource poor communities affected by mining or other industrial activities.

Translocation of Heavy Metals in Herbs under Urban Anthropogenic Pollution Conditions

This study aims to examine the translocation of heavy metals from urban soils to herbs in Tyumen (Russian Federation). The mobile and acid-soluble heavy metal fractions in soils, as well as the heavy metal contents in plants, were determined by atomic absorption spectrophotometry. The bioconcentration factor was estimated as the ratio of the amount of heavy metals in soils to that in plants. Heavy metal concentrations in urban soils were higher than those at the control site by 20% and by up to 10 times. The greatest heavy metal accumulation in both soils and plants was found at the battery manufacturing and metallurgical plants, exceeding the control levels of Pb and Fe by 2–17 times. The Cu, Fe and Mn contents in soil were positively correlated with those in plants. Heavy metal translocation by the plants was species-specific. The percentages of the mobile heavy metal fractions decreased in the following order: Mn > Zn > Cu > Fe. Heavy metal accumulation in Poa pratensis, Trifolium rubens, Vicia cracca, Matricaria chamomilla and Tussilago farfara in the urban sites compared to that at the control site decreased in the following order: Fe > Zn > Cu > Mn > Pb > Cd. Tussilago farfara exhibited the highest Fe, Mn and Zn accumulation, which exceeded the control levels by 17, 5 and 3.5 times, respectively. The heavy metal bioconcentration factors, indicators of translocation, decreased in the following order: Cu > Zn > Cd > Pb > Mn > Fe. The heavy metal translocation suggests the need to relocate industrial facilities to areas outside the city. Future monitoring of the study area is needed to ensure its long-term ecological safety. • The heavy metal concentration in urban soils was elevated indicating ecological risk • Iron was the most accumulated metal in all examined plant species • Heavy metal translocation in coltsfoot was higher than that in the four herb species

Comprehensive Evaluation of Metal Pollution in Urban Soils of a Post-Industrial City-A Case of Łódź, Poland.

The pollution of urban soils by metals is a global problem. Prolonged exposure of habitants who are in contact with metals retained in soil poses a health risk. This particularly applies to industrialized cities with developed transport networks. The aim of the study was to determine the content and spatial distribution of mobile metal fractions in soils of the city of Łódź and to identify their load and sources. Multivariate statistical analysis (principal component analysis (PCA), cluster analysis (CA)), combined with GIS, were used to make a comprehensive evaluation of the soil contamination. Hot-spots and differences between urban and suburban areas were also investigated. Metals were determined by atomic absorption spectrometry (AAS) after soil extraction with 1 mol L−1 HCl. In most sites, the metal content changes in the following order: Zn > Pb > Cu > Ni > Cd. About one-third of the samples are considerably (or very highly) contaminated, (contamination factor, CF > 3) with Cu, Pb, or Zn. In almost 40% of the samples, contaminated soils were found (pollution load index, PLI > 1). All metals have a strong influence on the first principal component (PC1), whereas second principal component (PC2) is related to pH. Polluted soils are located in the downtown, in the south and east part of the city. The distribution of contamination coincides with the urban layout, low emission sources and former industrial areas of Łódź.