Tatiana Bauer

Erratum to: Forms of Cu (II), Zn (II), and Pb (II) compounds in technogenically transformed soils adjacent to the Karabashmed copper smelter

Purpose The aim was to study Cu (II), Zn (II), and Pb (II) forms in technogenically transformed soils adjacent to the Karabashmed copper smelter.

Comparing two methods of sequential fractionation in the study of copper compounds in Haplic chernozem under model experimental conditions

PurposeIt is very important to obtain the information on the soils capacity to immobilize HMs and distribute them among soil components. The aim of this work was to study the fractional composition of Cu compounds in Haplic chernozem under model contamination conditions using different fractionation methods.Materials and methodsThe fractional composition of copper compounds in Haplic Chernozem artificially contaminated with copper acetate has been studied under model experimental conditions. General regularities and differences in the distribution of Cu forms in soils at the use of sequential fractionation by the Miller method modified by Berti and Jacobs (1996) and the Tessier method (Tessier et al. 1979) are revealed.Results and discussionThe differences are related to the metal affinity for specific carrier phases, as well as to the selectivity and extraction capacity of the reagents used in these methods. A significant increase in the most mobile exchangeable Cu fraction is observed in contaminated soils. Aluminosilicates and soil organic matter make the largest contribution to the adsorption and retention of Cu.ConclusionsThe Tessier method is more suitable for the separation of the total technogenic component from contaminated soils. The Miller method is more informative at the determination of loosely bound HM compounds because of the use of weaker extractants.

Determining the speciation of Zn in soils around the sediment ponds of chemical plants by XRD and XAFS spectroscopy and sequential extraction

For a correct assessment of risk of polluted soil, it is crucial to establish the speciation and mobility of the contaminants. The aim of this study was to investigate the speciation and transformation of Zn in strongly technogenically transformed contaminated Spolic Technosols for a long time in territory of sludge collectors by combining analytical techniques and synchrotron techniques. Sequential fractionation of Zn compounds in studied soils revealed increasing metal mobility. Phyllosilicates and Fe and Mn hydroxides were the main stabilizers of Zn mobility. A high degree of transformation was identified for the composition of the mineral phase in Spolic Technosols by X-ray powder diffraction. Technogenic phases (Zn-containing authigenic minerals) were revealed in Spolic Technosols samples through the analysis of their Zn K-edge EXAFS and XANES spectra. In one of the samples Zn local environment was formed by predominantly oxygen atoms, and in the other one mixed ZnS and ZnO bonding was found. Zn speciation in the studied technogenically transformed soils was due to the composition of pollutants contaminating the floodplain landscapes for a long time, and, second, this is the combination of physicochemical properties controlling the buffer properties of investigated soils. X-ray spectroscopic and X-ray powder diffraction analyses combined with sequential extraction assays is an effective tool to check the affinity of the soil components for heavy metal cations.

Time effect on the stabilization of technogenic copper compounds in solid phases of Haplic Chernozem

We studied the regularities of Cu stabilization in Haplic Chernozem contaminated with easily soluble (acetates, nitrates, sulfates, chlorides) and poorly soluble (acetates, nitrates, sulfates, chlorides) metal compounds in a five-year model experiment were studied. A low contents of Cu loosely bound compounds (LBC) (no >5% of total content) unchanging over time were revealed in the uncontaminated soil, which is indicative of the stability of soil processes. The Cu LBC content decreased over time in the soils contaminated with easily soluble compounds and increased in the soils contaminated with poorly soluble compounds. In both cases, the contents of Cu LBCs after 5 years of incubation remained higher than in the original uncontaminated soil. The effect of the attendant anions on the Cu LBC content was more apparent under the Cu application of 2000 mg kg-1 than at 300 mg kg-1. An inverse process characterized by an increase in the concentration of Cu LBCs over time was observed in the soil contaminated with Cu orthophosphate and oxide. Soil contaminated with different Cu compounds results in soil acidification. According to the effect on the decrease in soil pH, the attendant anions form the following series: SO42- ≈ Cl- > NO3- > Ac- > PO42- > O2-, which correlates with the Cu LBC content. Thus, the stabilization of Cu compounds in the soil is affected by the attendant anions and the interaction time of the metal with the soil solid phases.

Method of determining loosely bound compounds of heavy metals in the soil

Graphical abstract

Chemical partitioning of Zn in soil: application of two sequential extraction procedures

The data on the accumulation and distribution of heavy metal (HM) compounds in soils is necessary to assess and predict the ecological situation. The Zn fractional distribution in artificially contaminated soil by the most popular methods of sequential extraction (the well known Miller and Tessier methods) was studied. The sample studied was soil (Haplic Chernozem) artificially contaminated by Zn acetate (2000 mg kg−1), a priority pollutant in southern Russia. In order to estimate the role of different soil components in the Zn partitioning, the carbonates, Fe–Mn sesquioxides, and organic matter, were removed from the soil samples, prior to application of each sequential extraction scheme. Results showed a metal absence in the fraction bound to the removed soil component. The Miller method allows better tracing of the HM fractions loosely bound to the soil because of the use of weaker extractants with high complexing capacity, which hampers the reprecipitation of metals from the extract. The Tessier method is more suitable for the separation of the total anthropogenic component from contaminated soils. This is related to the higher extraction capacity of reagents. The differences in the fractional distribution of metal according to each method are most manifested in the contaminated soil.

Stabilization dynamics of easily and poorly soluble Zn compounds in the soil

Stabilization mechanisms of easily and poorly soluble Zn compounds in Haplic Chernozem are considered in a long-term incubation experiment, including the dissolution and hydrolysis of the Zn added compounds (acetate, nitrate, sulphate, chloride, phosphate, and oxide) at a rate of 300 and 2000 mg kg–1 and the following post-sorption metal transformation. The indicators of stabilization were changes in the content of Zn weakly bound compounds (WBCs) and soil pH. Stabilization of Zn acetate, nitrate, sulphate, chloride progressed during incubation for 5 years which resulted in a decrease of Zn WBCs and an increase in soil pH. In the soil contaminated with Zn phosphate and oxide, the content of Zn WBCs increased and the soil pH decreased with time.

Quantitative speciation of Zn in technosols using chemical fractionation and X-ray absorption spectroscopy

Human activity, such as mining, is often detrimental to the environment. For risk assessment of polluted soils, it is crucial to establish the speciation of the contaminants such as zinc. The aim of the work was to identify the Zn species in contaminated anthropogenically transformed soils known as ‘spolic technosols’. The Zn speciation in technosols was studied using a combined fractionation scheme and a set of X-ray synchrotron methods. Spolic technosols within the Karabashmed Company zone of the southern Urals have a very high level of Zn contamination. The role of soil components in metal fixation in both the loosely and firmly bound states were revealed. Iron oxides actively participate in the immobilization of Zn. The studу of the local structure of technosols by X-ray absorption spectroscopy showed that Zn is coordinated to six oxygen atoms forming a distorted octahedron with Zn–O bond lengths close to those in ZnSO4. The presence of short bonds, formed by Zn atoms, has been also revealed. Thus, the application of two independent methods can be helpful in defining Zn speciation in polluted soils.

Copper Adsorption by Chernozem Soils and Parent Rocks in Southern Russia

Laboratory data in Cu2+ adsorption by chernozems and parent rocks in Rostov region show that adsorption isotherms can be approximated by the Langmuir equation, whose parameters (Kl and C∞) were calculated for all of the samples. The values of C∞ show a strong negative correlation with the values of cationexchange capacity (CEC) (r =–0.88 at Р = 0.95), and Kl is correlated with the content of physical clay (particles <0.01 mm) (r = 0.78) and with clay (particles <0.001 mm) content in ordinary chernozem and southern chernozems of various particle size distribution (r = 0.80). Even stronger correlations were detected between these parameters in southern chernozems (r = 0.89 for the physical clay (PC) and r = 0.91 for the silt). However, none of the samples displays a significant correlation of C∞ and Kl with the contents of physical clay and silt. This led us to conclude that the composition of the samples, for example, their organic matter, can affect Cu2+ adsorption by the soils and parent rocks. Acidification mechanisms of the equilibrium solutions during the Cu2+ adsorption by soils are discussed, as also are the reasons for the absence of balance between Cu2+ adsorbed by soils and exchangeable cations transferred into solution. Analysis of the fine structures of the XANES and EXAFS spectra suggests that Cu2+ can form coordinated chelate complex compounds with humic acids (HA) of soils and can substitute Al3+ at octahedral sites when interacting with clay minerals in soils.

Phytoaccumulation of Benzo[a]pyrene by the Barley in Artificially Contaminated Soil

ABSTRACT The assessment of toxic effects of polycyclic aromatic hydrocarbons (PAHs) on Haplic chernozems soil was developed by using spring barley (Hordeum sativum distichum) bioaccumulation tendencies. Spring barley was used to estimate the negative effect of chernozemic soil contamination with benzo[a]pyrene (BaP), one the most carcinogenic and mutagenic PAHs compounds. The bioaccumulation tendencies were studied in soil spiking with BaP. Spiked doses were close to technogenic pressure level in studied area, 0–800 µg/kg of BaP. Condition and doses of BaP during 4 years of model experiment influenced morphometric characteristics of spring barley and rates of BaP uptake by plants. Exposure to the growth characteristics containing at least 20 µg/kg BaP promoted absorbing BaP by plants root system as well as increased roots length. Tendencies of phytotoxicity parameters inhibition were observed for all morphometric characteristics of spring barley as energy of germination, length of vegetation part, plant weight and ear height. Quantifiable levels of BaP uptake by spring barley roots exceeded vegetative part more than 2.5 times in all polluted variants. The constant of BaP semi-degradation in artificially polluted Haplic chernozems for 48 months of model experiment T50 reached 1.2–3.4 years. Thus, the BaP uptake by spring barley from chernozem soil contributes to the bioindication responses during environmental monitoring to assess the impact of BaP pollution.