Total concentrations of metals in soil are poor predictors of toxicity. In the last decade, considerable effort has been made to demonstrate how metal toxicity is affected by the abiotic properties of soil. Here this information is collated and shows how these data have been used in the European Union for defining predicted-no-effect concentrations (PNECs) of Cd, Cu, Co, Ni, Pb, and Zn in soil. Bioavailability models have been calibrated using data from more than 500 new chronic toxicity tests in soils amended with soluble metal salts, in experimentally aged soils, and in field-contaminated soils. In general, soil pH was a good predictor of metal solubility but a poor predictor of metal toxicity across soils. Toxicity thresholds based on the free metal ion activity were generally more variable than those expressed on total soil metal, which can be explained, but not predicted, using the concept of the biotic ligand model. The toxicity thresholds based on total soil metal concentrations rise almost proportionally to the effective cation exchange capacity of soil. Total soil metal concentrations yielding 10% inhibition in freshly amended soils were up to 100-fold smaller (median 3.4-fold, n ϭ 110 comparative tests) than those in corresponding aged soils or field-contaminated soils. The change in isotopically exchangeable metal in soil proved to be a conservative estimate of the change in toxicity upon aging. The PNEC values for specific soil types were calculated using this information. The corrections for aging and for modifying effects of soil properties in metal-salt-amended soils are shown to be the main factors by which PNEC values rise above the natural background range.

Environmental Science & Technology, 2004

We present a method to calculate critical limits of cationic heavy metals accounting for variations in soil chemistry. We assume the free metal ion concentration (M free) to be the most appropriate indicator of toxicity, combined with a protective effect of soil cations (e.g., H + , Ca 2+). Because soil metal cations tend to covary with pH, the concentration of M free exerting a given level of toxic effect (M free,toxic) can be expressed as a function of pH alone. We use linear regression equations to derive M free,toxic in toxicity experiments from soil pH, organic matter content, and endpoint soil metal. Chronic toxicity data from the literature, for plants, invertebrates, microbial processes, and fungi are interpreted in terms of an average log M free,toxic together with distributions of species sensitivity. This leads to critical limit functions to protect 95% of species, of the form log M free,CRIT) RpH + γ. Appreciable effects of soil pH upon log M free,CRIT are found, with R)-1.21 (Cu),-0.34 (Zn),-0.43 (Cd), and-0.83 (Pb). Critical limit functions in terms of the geochemically active soil metal (M soil,CRIT), that pool of metal which controls the free ion concentration, have also been derived, with soil pH and organic matter content as variables. The pH effect on M soil,CRIT is relatively small, with slopes of 0.05 (Cu), 0.19 (Zn), 0.16 (Cd), and 0.20 (Pb), since the effect of pH on M free,CRIT is countered by the variation of M free with pH.

Environmental Toxicology and Chemistry, 2006

Geoderma, 2009

Mixtures of artificial soil (10, 30 and 50% w/w) were prepared by adding sewage sludge (contaminated with 200 ± 13 mg kg − 1 Cu, 867 ± 18 mg kg − 1 Zn, 7 ± 0 mg kg − 1 Cd, 122 ± 6 mg kg − 1 Pb, 74 ± 2 mg kg − 1 Ni) to the fraction of infertile mineral soil. The effect of accelerated ageing of artificial soils on metal fractionation (assessed by sequential extractions), mobility (assessed by extraction with deionised water and using the Toxicity Leaching Procedure, TCLP), phyto-accessibility (diethylenetriamine pentaacetic acid, DTPA, extraction) and oral-accessibility (in vitro Physiologically Based Extraction Test, PBET) was simulated by exposing soils to alternate high (105°C) and low (−25°C) temperatures. Accelerated ageing affected the fractionation of contaminants metal-specifically and increased heavy metal mobility when assessed with the deionised water extraction test. On the other hand, accelerated ageing significantly decreased heavy metal mobility assessed with TCLP, phyto-accessibility (DTPA) and oral bio-accessibility in a simulated human gastrointestinal tract (PBET) and thus decreased the potential toxicity of metals in artificial soil mixtures. We propose accelerated ageing model as a simple tool to assess the long-term effect of environmental conditions on the metal availability status in artificial soils.

Science of The Total Environment, 2020

Biosolids application to arable land is a common, and cost-effective, practice but the impact of 8 prolonged disposal remains uncertain. We evaluated the dynamics of potentially toxic elements 9 (PTEs) at a long-established 'dedicated' sewage treatment farm. Soil metal concentrations exceeded regulations governing application of biosolids to non-dedicated arable land. However, measurement of isotopic exchangeability of Ni, Cu, Zn, Cd and Pb demonstrated 12 support for the 'protection hypothesis' in which biosolids constituents help immobilise 13 potential toxic metals (PTMs). Metal concentrations in a maize crop were strongly, and almost equally, correlated with all 'capacity-based' and 'intensity-based' estimates of soil metal 15 bioavailability. This was attributable to high correlations between soil factors controlling bioavailability (organic matter, phosphate etc.) on a site receiving a single source of PTMs. Isotopic analysis of the maize crop suggested contributions to foliar Pb from soil dust originating from neighbouring fields. There was also clear evidence of metal-specific effects of biosolids on soil metal lability. With increasing metal concentrations there was both 20 decreasing lability of Cd and Pb, due to interaction with increasing phosphate concentrations, and increasing lability of Ni, Cu and Zn due to weaker soil binding. Such different responses to prolonged biosolids disposal to arable soil should be considered when setting regulatory 23 limits. 24

2008

This report was prepared under contract to the Department of Defense Strategic Environmental Research and Development Program (SERDP). The publication of this report does not indicate endorsement by the Department of Defense, nor should the contents be construed as ...

E3S web of conferences, 2013

Metals can be stabilized by soil amendments that increase metals adsorption or alter their chemical forms. Such treatments may limit the risk related to the contamination through reduction of metal transfer to the food chain (reduction of metal uptake by plants and its availability to soil organisms) and metals migration within the environment. There is a need for experiments comparing various soil amendments available at reasonable amounts under similar environmental conditions. The other question is whether all components of soil environment or soil functions are similarly protected after remediation treatment. We conducted a series of pot studies to test some traditional and novel amendments and their combinations. The treatments were tested for several highly Zn/Cd/Pb contaminated soils. Among traditional amendments composts were the most effective-they ensured plant growth, increased soil microbial activity, reduced Cd in earthworms, reduced Pb bioaccessibility and increased share of unavailable forms of Cd and Pb.

The Science of the total environment, 2015

In the present study, the residual toxicity and impact of aged nZVI after a leaching experiment on heavy metal (Pb, Zn) polluted soils was evaluated. No negative effects on physico-chemical soil properties were observed after aged nZVI exposure. The application of nZVI to soil produced a significant increase in Fe availability. The impact on soil biodiversity was assessed by fluorescence in situ hybridization (FISH). A significant effect of nZVI application on microbial structure has been recorded in the Pb-polluted soil nZVI-treated. Soil bacteria molecular response, evaluated by RT-qPCR using exposure biomarkers (pykA, katB) showed a decrease in the cellular activity (pykA) due to enhanced intracellular oxidative stress (katB). Moreover, ecotoxicological standardised test on Caenorhabditis elegans (C. elegans) showed a decrease in the growth endpoint in the Pb-polluted soil, and particularly in the nZVI-treated. A different pattern has been observed in Zn-polluted soils: no change...

Environmental Science and Pollution Research, 2016

Remediation strategies using soil amendments should consider the time-dependence of metal availability to identify amendments that can sustainably reduce available pollutant concentrations over time. Drying-wetting cycles were applied on amendments, soils and soil+amendment mixtures, to mimic ageing at field level and investigate its effect on extractable Cd, Cu, Ni, Pb and Zn concentrations from three contaminated soils. The amendments investigated were municipal waste organic compost and biochars. The amendments, soils and mixtures were characterised by their physicochemical properties at different ageing times. The amendments were also characterised in terms of sorption capacity for Cd and Cu. The sorption capacity and the physicochemical properties of the amendments remained constant over the period examined. When mixed with the soils, amendments, especially the compost, immediately reduced the extractable metals in the soils with low pH and acid neutralisation capacity, due to the increase in pH and buffering capacity of the mixtures. The amendments had a relatively minor impact on the metal availability concentrations for the soil with substantially high acid neutralisation capacity. The most important changes in extractable metal concentrations were observed at the beginning of the experiments, ageing having a minor effect on metal concentrations when compared with the initial effect of amendments.

Archives of Environmental Contamination and Toxicology, 2012

Sewage sludge application to soils is regulated by its total metal content. However, the real risk of metals is determined by the fraction that is biologically available. The available fraction is highly related to the strength of metal binding by the matrix, which is a dynamic process. The evaluation of the fate of metals in time can contribute increased accuracy of ecological risk assessment. Aiming to evaluate short-term changes in metal availability when metals were applied to soil directly (metal-spiked) or by way of an organic matrix (sludge-amended), a laboratory experiment was performed using open microcosms filled with agricultural soil. A concentration gradient of industrial sludge (11, 15, 55, and 75 t/ha) that was contaminated predominantly with chromium, copper, nickel, and zinc, or soil freshly spiked with the same concentrations of these metals, were applied on top of the agricultural soil. After 0, 3, 6, and 12 weeks, total (HNO 3 69 %) and 0.01 M CaCl 2extractable metal concentrations in soil and metal content in the percolates were measured. Results demonstrated that comparison between sludge-amended and metal-spiked soils may give important information about the role of sludge matrix on metal mobility and availability in soil. In sludge-amended soils, extractable-metal concentrations were independent of the sludge concentration and did not change over time. In metal-spiked soils, metal extractability decreased with time due to ageing and transport of metals to deeper layers. In general, the sludge matrix increased the adsorption of metals, thus decreasing their mobility in soils.

Journal of Geochemical Exploration, 2016

2021

Sewage sludge is frequently applied as an agricultural fertilizer. However, this sludge often contains toxic metals, which contaminate the soil and create a risk for agriculture, as well as for humans, animals and plants in the surrounding environment. This dissertation analyzes the effects of long-term aging on the distribution and behavior of heavy metals (Cd, Cu, Pb, Zn, and Ni) in the soil, including solubility, mobility, bioavailability, and thus, toxicity. In 1978, a heavy application of metal-contaminated sewage sludge occurred at the Cornell Orchards in Ithaca, NY. This study examines the field site 40 years after this single application and compares it to a nearby site where sludge was not applied. The physical-chemical characteristics of the soil are measured by inductively coupled plasma optical emission spectroscopy (ICP-OES), and toxic metal availability is assessed using a sequential extraction procedure. The leaching of metals from the soil is estimated based on an experiment designed to simulate natural rainfall-driven leaching conditions. The bioavailability and plant uptake of the metals are determined by growing soybeans in sludge-contaminated and control soil samples. This dissertation also presents several new analytical methods that were developed in the course of the study, including the measurement of silver concentration using ICP-OES and the sequential extraction of metals from specific phases in the soil. This dissertation adds to our understanding of toxic metal solubility in the soil and proposes management methods to limit deleterious effects on soil productivity and environmental quality. Alejandro Parra, for his spiritual guidance and support. Most of all I thank my daughter, Anna, and my nephew, Alexander Naydich, who inspired and encouraged me in every step of my way throughout my doctoral degree and helped proofread my dissertation. I also thank my mother, sister and my brother-in-law for their continuing support and always being there for me. vi TABLE OF CONTENTS BIOGRAPHICAL SKETCH III ACKNOWLEDGEMENTS V LIST OF TABLES VIII LIST OF FIGURES X CHAPTER 1: INTRODUCTION CAUSES OF TOXIC METAL CONTAMINATION IN SOILS POSSIBLE EFFECTS OF TOXIC METAL CONTAMINATION IN SOILS REGULATION OF SEWAGE SLUDGE DISPOSAL REASONS FOR CONCERN PRIOR STUDIES OF THE LONG-TERM FATE OF TOXIC METALS IN SOIL AIMS OF THIS STUDY REFERENCES FOR CHAPTER 1 CHAPTER 2: PHYSICAL-CHEMICAL CHARACTERISTICS OF A SOIL AMENDED WITH SEWAGE SLUDGE 40 YEARS AGO INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION AND CONCLUSION REFERENCES FOR CHAPTER 2 CHAPTER 3: CHARACTERIZATION OF TOXIC METAL AVAILABILITY IN A LONG-TERM SEWAGE SLUDGE-AMENDED SOIL USING SEQUENTIAL EXTRACTION INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION AND CONCLUSION REFERENCES FOR CHAPTER 3 CHAPTER 4: LONG TERM LEACHING OF TOXIC METALS IN A SEWAGE SLUDGE-AMENDED SOIL INTRODUCTION vii MATERIALS AND METHODS RESULTS AND DISCUSSION REFERENCES FOR CHAPTER 4 CHAPTER 5: PLANT UPTAKE OF TOXIC METALS FROM A CONTAMINATED SOIL 40 YEARS AFTER SEWAGE SLUDGE APPLICATION INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION CONCLUSION REFERENCES FOR CHAPTER 5 CHAPTER 6: METHODS FOR MEASURING TRACE SILVER IN SLUDGE, PLANT TISSUE AND SOIL SAMPLES "A nation that destroys its soils destroys itself."-Franklin Roosevelt, U.S. President, 1937. "Le microbe n'est rien, le terrain est tout." (The microbe is nothing, the terrain is everything.)-Louis Pasteur Chapter 1: Introduction Over the years while working at the laboratory, I have spoken with many farmers, doctors, government organizations, schoolteachers, and community gardeners who often ask me the same questions: "Is my soil toxic? Will it affect my plants? How long will it take for my soil to recover from toxic metals?" This led me to start studying the behavior of toxic metals in contaminated soil to try to get a better understanding of their fate over time. Over the course of my work, I learned that many projects I worked on involved soil that was polluted due to the use of industrial waste as a fertilizer. I became interested in understanding whether the use of such waste in agriculture creates any problems for the environment and how long it might take for soil that has been contaminated with toxic metals to recover. Causes of toxic metal contamination in soils Generally, toxic metals or metalloids can accumulate in soils as a result of industrial activities (e.g., mine tailings, sewage sludge, coal burning, accidental spills) or agricultural processes (e.g., fertilizer or pesticide application, animal waste, wastewater irrigation) (Wuana et al.,2011). Common contaminants include lead, chromium, arsenic, zinc, cadmium, copper, mercury and nickel (Evanko et al., 1997).

Advances in Environmental Research, 2003

Environmental Toxicology and Chemistry, 2014

The contribution of the nature instead of the total content of soil parameters relevant to metal bioavailability in lettuce was tested using a series of low-polluted Mediterranean agricultural calcareous soils offering natural gradients in the content and composition of carbonate, organic, and oxide fractions. Two datasets were compared by canonical ordination based on redundancy analysis: total concentrations (TC dataset) of main soil parameters (constituents, phases, or elements) involved in metal retention and bioavailability; and chemically defined reactive fractions of these parameters (RF dataset). The metal bioavailability patterns were satisfactorily explained only when the RF dataset was used, and the results showed that the proportion of crystalline Fe oxides, dissolved organic C, diethylenetriamine-pentaacetic acid (DTPA)-extractable Cu and Zn, and a labile organic pool accounted for 76% of the variance. In addition, 2 multipollution scenarios by metal spiking were tested that showed better relationships with the RF dataset than with the TC dataset (up to 17% more) and new reactive fractions involved. For Mediterranean calcareous soils, the use of reactive pools of soil parameters rather than their total contents improved the relationships between soil constituents and metal bioavailability. Such pool determinations should be systematically included in studies dealing with bioavailability or risk assessment. Environ Toxicol Chem 2015;34:37-44. # 2014 SETAC

Journal of Environmental Sciences, 2009

The concentration and speciation of heavy metals in soil solution isolated from long-term contaminated soils were investigated. The soil solution was extracted at 70% maximum water holding capacity (MWHC) after equilibration for 24 h. The free metal concentrations (Cd 2+ , Cu 2+ , Pb 2+ , and Zn 2+) in soil solution were determined using the Donnan membrane technique (DMT). Initially the DMT was validated using artificial solutions where the percentage of free metal ions were significantly correlated with the percentages predicted using MINTEQA2. However, there was a significant difference between the absolute free ion concentrations predicted by MINTEQA2 and the values determined by the DMT. This was due to the significant metal adsorption onto the cation exchange membrane used in the DMT with 20%, 28%, 44%, and 8% mass loss of the initial total concentration of Cd, Cu, Pb, and Zn in solution, respectively. This could result in a significant error in the determination of free metal ions when using DMT if no allowance for membrane cation adsorption was made. Relative to the total soluble metal concentrations the amounts of free Cd 2+ (3%-52%) and Zn 2+ (11%-72%) in soil solutions were generally higher than those of Cu 2+ (0.2%-30%) and Pb 2+ (0.6%-10%). Among the key soil solution properties, dissolved heavy metal concentrations were the most significant factor governing free metal ion concentrations. Soil solution pH showed only a weak relationship with free metal ion partitioning coefficients (K p) and dissolved organic carbon did not show any significant influence on K p .

Journal of Hazardous Materials, 2009

We investigated the pore-water content and speciation of copper (Cu), zinc (Zn), cadmium (Cd) and lead (Pb) in a range of uncontaminated and long-term contaminated soils in order to establish their potential bioaccessibility to soil biota, plants and humans. Among the samples, soil pH (0.01 M CaCl 2 ) ranged from 4.9 to 8.2. The total metal content of the uncontaminated soils ranged from 3.8 to 93.8 mg Cu kg −1 , 10.3 to 95 mg kg −1 Zn, 0.1 to 1.8 mg Cd kg −1 and 5.2 to 183 mg kg −1 Pb, while metal content in the contaminated soils ranged from 104 to 6841 mg Cu kg −1 , 312 to 39,000 mg kg −1 Zn, 6 to 302 mg Cd kg −1 and 609 to 12,000 mg kg −1 Pb. Our analysis of pore-water found the Cu concentrations to be much higher in contaminated soils than in uncontaminated soils, with the distribution coefficients (K d ) correlating significantly with the log of dissolved organic carbon concentrations. Despite the high total metal content of the contaminated soil, Zn, Cd and Pb were not generally found at elevated levels in the pore-water with the exception of a single contaminated soil. A long period of ageing and soil weathering may have led to a substantial reduction in heavy metal concentrations in the pore-water of contaminated soils. On the other hand, Pb bioaccessibility was found to be comparatively high in Pb contaminated soils, where it tended to exceed the total Pb values by more than 80%. We conclude that, despite the extensive ageing of some contaminated soils, the bioaccessibility of Pb remains relatively high.

2007

Changes in the soil chemical environment can be expected to increase the leaching of trace metals bound in soils. In this study the mobility of trace metals was monitored in a column experiment for two contaminated urban soils. Four different treatments were used (i.e. rain, acid rain, salt and bark). Leachates were analysed for pH, dissolved organic carbon (DOC) and for seven trace metals (cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb) and zinc (Zn)). The salt treatment produced the lowest pH values (between 5 and 6) in the effluent whereas the DOC concentration was largest in the bark treatment (40-140 mg L −1 ) and smallest in the salt and acid treatments (7-40 mg L −1 ). Cadmium, Ni and Zn were mainly mobilised in the salt treatment, whereas the bark treatments produced the highest concentrations of Cu and Pb. The concentrations of Cu, Cr, and Hg were strongly correlated with DOC (r 2 = 0.90, 0.91 and 0.96, respectively). A multi-surface geochemical model (SHM-DLM) produced values for metal dissolution that were usually of the correct magnitude. For Pb, however, the model was not successful indicating that the retention of this metal was stronger than assumed in the model. For all metals, the SHM-DLM model predicted that soil organic matter was the most important sorbent, although for Pb and Cr(III) ferrihydrite was also important and accounted for between 15 and 50% of the binding. The results confirm the central role of DOC for the mobilization of Cu, Cr, Hg and Pb in contaminated soils.

Journal of Environmental Management, 2017

Journal of Environmental Quality, 1998

Three unbuffered salt solutions used to estimate soil trace metal bioavailability were compared. The objective was to evaluate chemical speciation of Cd, Cu, Pb, and Zn in 0.01 M CaCl2, 0.1 M NaNO3, and 1 M NH4NO3 extracts. The metal in each extract were speciated with a model that was optimized experimentally using an exchange resin. In NH4NO3, Cd, Cu, and Zn were completely complexed by NH3. In extracts of pH lower than 6.5, Pb was essentially present as free Pb2+ and metal‐organic complexes. In extracts of higher pH, PbCO3 and free Pb2+ were dominant. In CaCl2, Cu and Zn were mainly present as organic complexes and free Zn2+, respectively. In all extracts, 50% of Cd was free Cd2+ and 50% CdCl+. As pH increased, the proportions of free Pb2+ and organic complexes decreased while those of inorganic complexes increased. In NaNO3, Cd, Cu, and Zn were, respectively, mainly present as free Cd2+, organic complexes and free Zn2+. Speciation of Pb changed with pH as in NH4NO3. Similarities...

Integrated Environmental Assessment and Management, 2013

European Journal of Soil Science, 2011

Isotopic exchange (IE) of trace metals is an established method for characterizing metal reactivity in soils, but it is still unclear which metal species are isotopically exchangeable. In this study, we used IE to quantify 'labile' zinc (Zn) in 51 contaminated soils that were previously studied by Zn K-edge X-ray absorption fine structure (XAFS) spectroscopy and sequential extraction (SE). All soils had been contaminated by runoff water from 17-to 74-year-old galvanized power-line towers. They covered a wide range in pH (4.0-7.7), organic carbon (0.9-10.2%), clay (3.8-45.1%) and Zn concentrations (251-30 090 mg kg −1 ). Isotopic exchange was also performed on selected Zn minerals used as references for linear combination fitting of XAFS spectra. The isotopically exchangeable fraction (%E) of Zn generally decreased with increasing pH, but small %E values were also observed for acidic soils with a large fraction of Zn in hydroxy-interlayered minerals (Zn-HIM). The fraction of Zn identified by XAFS spectroscopy as (tetrahedrally and octahedrally coordinated) 'sorbed Zn' agreed reasonably well with the isotopically exchangeable fraction but was in many cases larger than the %E, indicating that some 'sorbed Zn' may be isotopically non-exchangeable, such as Zn sorbed in micropores of Fe oxyhydroxides. Zinc identified by XAFS spectroscopy as Zn precipitates (Zn phyllosilicates, Zn-layered double hydroxide (Zn-LDH) or hydrozincite) or as Zn-HIM was largely isotopically non-exchangeable ('nonlabile'). Comparison between IE and extraction results suggested that the isotopically exchangeable Zn was mainly extracted in the first two fractions of the SE. However, non-labile Zn was also extracted in these first two fractions for some soils, including a hydrozincite-containing soil. Despite the presence of Zn-LDH and/or Zn phyllosilicates in almost all soils, the Zn concentrations in solution and labile Zn increased with increasing soil total Zn at a given pH, which contradicts the concept of precipitation control by a single phase. Solution Zn was well predicted from the labile Zn following a sorption model. published sequential extraction and Zn K-edge X-ray absorption fine structure (XAFS) spectroscopy data.

Journal of the Science of Food and Agriculture, 2011

Contamination of agricultural soils with trace elements (TEs) through municipal and industrial wastes, atmospheric deposition and fertilisers is a matter of great global concern. Since TE accumulation in edible plant parts depends on soil characteristics, plant genotype and agricultural practices, those soil-and plant-specific options that restrict the entry of harmful TEs into the food chain to protect human and animal health are reviewed. Soil options such as in situ stabilisation of TEs in soils, changes in physicochemical parameters, fertiliser management, element interactions and agronomic practices reduce TE uptake by food crops. Furthermore, phytoremediation and solubilisation as alternative techniques to reduce TE concentrations in soils are also discussed. Among plant options, selection of species and cultivars, metabolic processes and microbial transformations in the rhizosphere can potentially affect TE uptake and distribution in plants. For this purpose, genetic variations are exploited to select cultivars with low uptake potential, especially low-cadmium accumulator wheat and rice cultivars. The microbial reduction of elements and transformations in the rhizosphere are other key players in the cycling of TEs that may offer the basis for a wide range of innovative biotechnological processes. It is thus concluded that appropriate combination of soil-and plant-specific options can minimise TE transfer to the food chain.

Environmental Toxicology and Chemistry, 2014

The contribution of the nature instead of the total content of soil parameters relevant to metal bioavailability in lettuce was tested using a series of low-polluted Mediterranean agricultural calcareous soils offering natural gradients in the content and composition of carbonate, organic, and oxide fractions. Two datasets were compared by canonical ordination based on redundancy analysis: total concentrations (TC dataset) of main soil parameters (constituents, phases, or elements) involved in metal retention and bioavailability; and chemically defined reactive fractions of these parameters (RF dataset). The metal bioavailability patterns were satisfactorily explained only when the RF dataset was used, and the results showed that the proportion of crystalline Fe oxides, dissolved organic C, diethylenetriamine-pentaacetic acid (DTPA)-extractable Cu and Zn, and a labile organic pool accounted for 76% of the variance. In addition, 2 multipollution scenarios by metal spiking were tested that showed better relationships with the RF dataset than with the TC dataset (up to 17% more) and new reactive fractions involved. For Mediterranean calcareous soils, the use of reactive pools of soil parameters rather than their total contents improved the relationships between soil constituents and metal bioavailability. Such pool determinations should be systematically included in studies dealing with bioavailability or risk assessment. Environ Toxicol Chem 2015;34:37-44. # 2014 SETAC

Environmental Science and Pollution Research, 2014

Areas polluted by the persistent presence of metal(loid)s induce health problems, especially when recreational activities (on land or water) promote human exposure to the pollutants. This study focuses on one of the most encountered worldwide mining waste, i.e. those from the extraction of Pb-Zn-Ag. The representative Pb-Zn-rich tailing (about 64, 100 m 3 ) sampled is located near a soccer field and a famous river for fishing. The scientific interests is relative to: (1) mobility and bioaccessibility of metal(oid)s, (2) human risk assessments and (3) relationship between human risks and solid-bearing phases in the environment. Soccer field soils, tailings and sediments from the nearby river were sampled; moreover, metal(loid) speciation (from BCR experiments) and bioaccessibility were measured and solid speciation performed by X-ray diffraction and electron microscopy in order to highlight metal(loid) dispersion and impact. Results demonstrate that the soccer field is highly contaminated by Pb, Zn, As and Sb due primarily to waste runoff. In terms of risk assessment, Pb and As human bioaccessibility highlights the major health risk (48 and 22.5 % of human bioaccessibility, respectively). Since local populations are regularly in close contact with metal(loid)s, the health risk due to pollutant exposure needs to be reduced through sustainable waste disposal and the rehabilitation of polluted sites.

Integrated Environmental Assessment and Management, 2014

Integrated Environmental Assessment and Management, 2012

The European Union's Existing Substances regulation (EEC 793/93) was developed to assess the ecological risks posed by chemical substances such as Ni and includes the assessment of secondary poisoning risks. The basic structure of this secondary poisoning risk assessment followed the Technical Guidance Document on Risk Assessment and thus included development of predicted exposure concentrations (PECs) and predicted no-effect concentrations (PNECs). A PEC to PNEC ratio greater than 1.0 is indicative of potential risk. The Technical Guidance Document on Risk Assessment provides a generic framework for assessing secondary poisoning risks and prescribes the following terrestrial food chain: soil ! earthworm ! worm-eating bird or mammal. This secondary poisoning evaluation was conducted at the regional level, and it was found that the generic approach resulted in widespread estimates of potential risk, even at ambient Ni soil concentrations. Accordingly, a tiered approach was used with increasing levels of refinement, including consideration of bioavailability, consideration of a variable diet, and development of dose-based PNEC values. Based on the refined approach, all PEC to PNEC ratios were less than 1.0, except for a ratio of 1.4 in a scenario focused on a regional clay soil, which was of natural origin. This regional-level secondary poisoning evaluation highlighted key risk assessment components that should be considered in future localized secondary poisoning assessments of Ni and other metals, including ingestion rate to body weight ratios for the test organisms used to derive PNECs versus the representative wildlife species evaluated, the appropriateness of high assessment factors for deriving PNECs for naturally occurring essential elements, representative dietary compositions, relative metal bioavailability between the dietary toxicity study and natural diets, and ground-truthing of the risk predictions versus background concentrations. Integr Environ Assess Manag 2012;8:107-119. ß 2011 SETAC

European Journal of Soil Science, 2012

Integrated Environmental Assessment and Management, 2013

The development of media-specific ecological values for risk assessment includes the derivation of acceptable levels of exposure for terrestrial wildlife (e.g., birds, mammals, reptiles, and amphibians). Although the derivation and subsequent application of these values can be used for screening purposes, there is a need to identify toxicological effects thresholds specifically for making remedial decisions at individual contaminated sites. A workshop was held in the fall of 2012 to evaluate existing methods and recent scientific developments for refining ecological soil screening levels (Eco-SSLs) and improving the derivation of site-specific ecological soil clean-up values for metals (Eco-SCVs). This included a focused session on the development and derivation of toxicity reference values (TRVs) for terrestrial wildlife. Topics that were examined included: methods for toxicological endpoint selection, techniques for dose-response assessment, approaches for cross-species extrapolation, and tools to incorporate environmental factors (e.g., metal bioavailability and chemistry) into a reference value. The workgroup also made recommendations to risk assessors and regulators on how to incorporate site-specific wildlife life history and toxicity information into the derivation of TRVs to be used in the further development of soil cleanup levels.

Environmental Science and Pollution Research

Organic waste products (OWP) application to crop lands makes possible nutrients recycling. However, it can result in long-term accumulation of trace elements (TE) in soils. The present study aimed at (i) assessing the impact of regular applications of urban composts and manure on the TE contents of topsoils and crops in a long-term field experiment, (ii) comparing the TE mass balances with the stock variations of TE in soils, and (iii) proposing a prospective evaluation of this practice, based on estimated soil safe threshold values and simulations of soil TE accumulation for 100 years. In the long-term field experiment, physico-chemical properties and TE contents (Cd, Cr, Cu, Hg, Ni, Pb and Zn) have been measured in OWP, soils, plants and leaching waters for the period 1998–2015, and used for mass balance calculations and long-term simulations of TE accumulations. The composts of green wastes and sludge (GWS) and of municipal solid waste (MSW) were the OWP with the largest TE conte...

Environments

Zinc (Zn) and arsenic (As) occur as mixed contaminants in soil and the interactions between them remain unclear. Here, we investigated a Zn2+ and H2AsO4− mixture interaction and their effects on plant growth. Three different soils were spiked with ZnCl2 and NaH2AsO4, each dosed singly or in combination. The soils were leached to remove excessive salt and were aged (>7 days), before toxicity testing using a 5-day root elongation of barley (Hordeum vulgare L.). In the single treatments, the 50% inhibitory effect concentrations in the soil (EC50, total measured concentration) were 2000–3800 mg Zn kg−1 and 96–620 mg As kg−1, depending on the soils. The mixture analyses based on the total concentrations showed overall and significant Zn–As antagonism in two soils, either based on the concentration addition (CA) or independent action (IA) model, whereas no significant interactions (either CA or IA) were found in one soil, which had the lowest content of Fe-oxides. The soil solution com...

Minerals

This study was carried out in Złoty Stok, a historical centre of gold and arsenic mining. Two kinds of soil material, containing 5020 and 8000 mg/kg As, represented a floodplain meadow flooded in the past by tailings spills and a dry meadow developed on the plateau built of pure tailings, respectively. The effects of soil treatment with a cattle manure and mineral fertilizers were examined in an incubation experiment. Soil pore water was collected after 2, 7, 21, 90, and 270 days, using MacroRhizon samplers and analyzed on As concentrations and toxicity, and assessed in three bioassays: Microtox, the Microbial Assay for Risk Assessment (MARA), and Phytotox, with Sinapis alba as a test plant. In all samples, As concentrations were above 4.5 mg/L. Fertilization with manure caused an intensive release of As, and its concentration in pore water of floodplain soil reached 81.8 mg/L. Mineral fertilization caused a release of As only from the pure tailings soil. The results of bioassays, p...

Communications in Soil Science and Plant Analysis, 2014

Rapid and effective methods are needed to analyze large numbers of grain samples for iron (Fe) and zinc (Zn) to select cultivars that are denser in these minerals. This study was conducted for the comparative evaluation of ground and unground grain samples for determining total Fe and Zn in pearl millet and sorghum cultivars with a range in seed size. In general, the results of the study with 50 pearl millet and 49 sorghum cultivars showed that grain Fe and Zn, in these relatively small-seeded crops, can be routinely determined using unground samples. Highly significant positive correlations were found between the values of Fe and Zn in grains of these crops determined using ground and ground samples.

Environmental Toxicology and Chemistry, 2016

This document is the author's final manuscript version of the journal article, incorporating any revisions agreed during the peer review process. There may be differences between this and the publisher's version. You are advised to consult the publisher's version if you wish to cite from this article.

Soil Systems, 2019

Copper (Cu)-based fungicides have been an important tool against disease in viticulture since the 19th century. However, their prolonged use can lead to Cu accumulation in the soil and negatively affect soil microbiology and plant growth. The application of biochar (BC)-based amendments is a promising mitigation strategy, due to BC's longevity in the soil and its potential to complex Cu. This study investigated temporal changes in the efficiency of various compost-and BC-based amendments to immobilize Cu in a calcareous and a slightly acidic Austrian vineyard soil. The immobilization of both historically accumulated Cu and freshly spiked Cu (250 mg kg −1) was studied. The soils were treated with six combinations of amendments containing compost and BC, with and without surface modification, as well as an additional lime treatment for the acidic soil. After treatment, the soils were incubated for 6 weeks and 3 years, after which the 0.01 M CaCl 2-extractable Cu was measured. The amendments were not effective in reducing the mobility of the historically accumulated Cu in the calcareous soil, with pure compost doubling the soluble Cu. Pure wood-chip BC was the only organic amendment that led to a reduction (by 20%) of soluble Cu after 6 weeks in the acidic soil; however, after 3 years, the same amendment reduced soluble Cu by 40% and all other tested amendments were also effective in reducing the mobility of the historically accumulated Cu. The lime treatment achieved the greatest reduction in Cu mobility (56%). Freshly spiked Cu was strongly immobilized in both unamended soils, with 0.06% and 0.39% extractable after 6 weeks in the calcareous and slightly acidic soil, respectively. The amendments did not effectuate additional Cu immobilization in the calcareous soil, but in the acidic soil, the soluble Cu was further reduced to between 25% and 50% of the unamended control by the tested organic amendments and to 6% by the lime treatment after 6 weeks of incubation. Overall, the acidic soil exhibited a stronger response to the amendments than did the calcareous soil, suggesting the amendments' effect on the soil pH was an important factor for Cu immobilization in this study. These results show the importance of developing site-specific remediation strategies for Cu accumulation in agricultural soils.

CLEAN - Soil, Air, Water

Ecotoxicity of three potentially toxic metals (PTM) (Cu, Zn and Cr) in a slightly acidic sandy soil was tested using the soil respiration test (OECD-217) in order to determine EC50 values for the carbon transformation activity of microorganisms. Addition of an organic amendment of Populus leaves was also crossed with metal spiking in order to investigate possible interaction with metal toxicity. Soil respiration was measured at day 1 and day 28 after the soil spiking with the PTM to assess short-term effects on soil microbial activity. Of the three metals tested, Cu showed the highest toxicity at the longest exposure times (day 28) and Zn showed a strong inhibitory effect in the short-term (day 1), even though later toxicity diminished significantly. Cr was the least toxic studied PTM. Organic amendment outweighs any adverse effects of these metals, increasing soil respiration, even in the treatments with high doses of metals.

Integrated Environmental Assessment and Management, 2014

This paper represents 1 of 6 articles generated from a workshop entitled "Ecological soil levels: next steps in the development of metal clean-up values" (September 2012, Sundance, Utah, USA). The purpose of the workshop was to provide managers and decision makers of contaminated sites in North America with appropriate methods for developing soil clean-up values that are protective of ecological resources. The workshop focused on metals and other inorganic contaminants because of their ubiquity at contaminated sites and because their natural occurrence makes it difficult to determine adverse levels.

Acta Agriculturae Scandinavica, Section B - Soil & Plant Science, 2013

Regression modelling and statistical correlations are often developed to aid reasonable predictions of metal solubility and free metal ion in terrestrial ecosystems. In the present study, we test how regression model predictions of metal solubility and free metal ion correlate with metal concentrations in plants. We previously optimised a model for the prediction of metal solubility and free metal ion concentrations in soil solution from sites collected in the Danube basin of Eastern Croatia, containing total metal concentration (concentrated HNO 3 ), soil pH, soil organic matter (SOM) and dissolved organic carbon (DOC) as model parameters. In the present study, we report how our optimised models correlate with metal concentration in plants reported by Lonc ˇaric ´et al., which was based on a study from a smaller part of the same sampling area. Our default regression model and further optimised model predicted metal solubility and free metal ion concentrations. These predictions correlated well with Fe, Mn, Zn and Cd concentrations in wheat grain, but the different extraction methods and parameter optimisations affected the significance of correlations differently. Due to the low concentrations of total metal concentrations in soil and little variation in SOM, the soil pH was the only variable, in addition to the total metal controlling the metal solubility, free metal ion in soil water and also the concentrations in wheat grain. Results show that after optimisation for the few most important soil chemical variables regression models can predict metal concentrations in plants fairly well. For this particular study, optimisation for total metal , soil pH and perhaps also SOM and DOC are sufficient.

2022

Biochar has recently aroused great interest for the restoration of contaminated soils since it improves soil properties and induces the immobilization of pollutants. This study evaluates the use of biochar from plant pruning, applied as an amendment, for immobilizing metal(loid)s in a highly contaminated soil as well as for reducing the phytotoxicity of these pollutants by promoting natural revegetation. For this purpose, a bioassay with Trifolium pratense L. was used to test the effectiveness of the soil amendment in greenhouse conditions. Three treatments were carried out including soil contaminated with metal(loid)s (RA), and this soil was amended with biochar at different dosage: 4% (RA4B) and 8% (RA8B). A non-contaminated soil (NC) from a nearby area not affected by contamination was used as a control. The results show that biochar increased soil pH by several units depending on the dose used, 8% being the most effective one. Biochar treatments also reduced soluble and bioavailable forms of Zn and Cu. Likewise, phytotoxicity was significantly reduced, promoting seed germination and biomass with plant growth values similar to the nonpolluted soil. In light of the results obtained, the evaluation of the bioremediation potential of biochar under field conditions can be considered.

Inorganics, 2019

Nickel (Ni) metal and Ni compounds are widely used in applications like stainless steel, alloys, and batteries. Nickel is a naturally occurring element in water, soil, air, and living organisms, and is essential to microorganisms and plants. Thus, human and environmental nickel exposures are ubiquitous. Production and use of nickel and its compounds can, however, result in additional exposures to humans and the environment. Notable human health toxicity effects identified from human and/or animal studies include respiratory cancer, non-cancer toxicity effects following inhalation, dermatitis, and reproductive effects. These effects have thresholds, with indirect genotoxic and epigenetic events underlying the threshold mode of action for nickel carcinogenicity. Differences in human toxicity potencies/potentials of different nickel chemical forms are correlated with the bioavailability of the Ni2+ ion at target sites. Likewise, Ni2+ has been demonstrated to be the toxic chemical speci...

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