The scientific landscape of phytoremediation of tailings: a bibliometric and scientometric analysis.

This article seeks to evaluate the scientific landscape of the phytoremediation of mine tailings through a series of bibliometric and scientometric techniques. Phytoremediation has emerged as a sustainable approach to remediate metal-contaminated mine waste areas. A scientometric analysis of 913 publications indexed in Web of Science from 1999 to 2023 was conducted using CiteSpace. The results reveal an expanding, interdisciplinary field with environmental sciences as the core category. Keyword analysis of 561 nodes and 2,825 links shows a focus on plant-metal interactions, microbial partnerships, bioavailability, and field validation. Co-citation analysis of 1,032 nodes and 2,944 links identifies seminal works on native species, plant-microbe interactions, and amendments. Temporal mapping of 15 co-citation clusters indicates a progression from early risk assessments and native plant inquiries to integrated biological systems, economic feasibility, and sustainability considerations. Recent trends emphasize multidimensional factors influencing adoption, such as plant-soil-microbe interactions, organic amendments, and field-scale performance evaluation. The findings demonstrate an intensifying translation of phytoremediation from scientific novelty to engineering practice. This quantitative and qualitative analysis of research trends aids in understanding the development of phytoremediation for mine tailings. The results provide valuable insights for researchers and practitioners in this evolving field.

Cartographic evaluation of the risk of natural elements' deficiency in the soil cover provoking spatial variation of the endemic morbidity level (on example of thyroid morbidity among population of the Central Federal District, Russia).

The main goal of the study is to evaluate the contribution of the natural geochemical risk in the central part of the Eastern European Plain to the spatial distribution of human diseases provoked by the deficiency of biologically significant microelements (Co, Cu, and I) in the environment. The Central Federal District (CFD) of Russia, located in the Eastern European Plain is characterized by a deficiency of Co, Cu, and I in the environment (soils, local food). To access the risk of thyroid diseases associated with Co, Cu, and I content in soils of the CFD based on published data of trace elements concentrations and digital soil map we create maps of the elements variation in soil cover allowing to estimate their mean concentration in the regions. The obtained cartographic estimates are comparable with the previously published assessments and averaged study results at the regional level. Comparison with medical data on thyroid disease morbidity from 2013 to 2017 at the regional level showed a significant inverse correlation with the cartographic estimates of soil I and combined (Co + Cu + I) status with due consideration of soil structure (12 regions, except for those affected by technogenic radioiodine contamination and Moscow urbanized regions). The urban population suffered from thyroid diseases to a higher extent in comparison with the rural population, which corresponds to our previous estimates. The results confirmed the possibility of assessing the geochemical risk of endemic diseases based on geochemical soil maps and identifying the negative contribution of micronutrient deficiency in the environment to endemic morbidity in the population.

Contamination of As, Cd, Cr, Hg and Pb in soils in Arica commune (Chile).

The objectives of this study are (a) to determine the background concentration of As, Cd, Cr, Hg and Pb in Arica commune; (b) to determine the degree of soil contamination in Arica city using environmental indices and (c) to evaluate the human health risk of these potentially toxic elements. In the rural area of Arica commune, 169 samples were taken and 283 samples were taken in the urban area of Arica city. Total concentrations of Cd, Pb and Cr were determined by EPA 3052 and EPA 6010 C. Mercury was determined by EPA 7473. Arsenic was determined by EPA 7061A. The available concentrations of As and Cr were determined by dilute hydrochloric acid and EPA 6010C. Environmental indices were applied for pollution and US EPA model was used to evaluate human health risk. Background concentrations were As 18.2, Cd 1.12, Cr 73.2, Hg 0.02 and Pb 11.8 mg kg-1, respectively. Environmental indices show that soil samples are located between slightly contaminated to extremely contaminated. Human health risk analysis shows that children have higher levels of risk than adults. The analysis with available concentrations of As and Cr shows no carcinogenic risk for adults and children, but 81% and 98% of the samples were between 10-6 and 10-4, that means intermediate risk.

An extension of the characteristic curve model of plant species behavior in heavy metal soils.

This article proposes a mathematical model to characterize phytoremediation processes in soils contaminated with heavy metals. In particular, the proposed model constructs characteristic curves for the concentrations of several metals (As, Cd, Cu, Fe, Pb, Sb, and Zn) in soils and plants based on the experimental data retrieved from several bibliographical sources comprising 305 vegetal species. The proposed model is an extension of previous models of characteristic curves in phytoremediation processes developed by Lam et al. for root measurements using the bioconcentration factor. However, the proposed model extends this approach to consider roots, as well as aerial parts and shoots of the plant, while at the same time providing a less complex mathematical formula compared to the original. The final model shows an adjusted R2 of 0.712, and all its parameters are considered statistically significant. The model may be used to assess samples from a given plant species to identify its potential as an accumulator in the context of soil phytoremediation processes. Furthermore, a simplified version of the model was constructed using an approximation to provide an easy-to-compute alternative that is valid for concentrations below 37,000 mg/kg. This simplified model shows results similar to the original model for concentrations below this threshold and it uses an adjusted factor defined as [Formula: see text] that must be compared with a threshold depending on the metal, type of measurement, and target (e.g., accumulator or hyperaccumulator). The full model construction shows that 90 out of the 305 species assessed have a potential behavior as accumulators and 10 of them as hyperaccumulators. Finally, out of the 1405 experimental measurements, 1177 were shown to be accumulators or hyperaccumulators. In particular, 85% of the results coincide with the reported values, thus validating the proposed model.

Heavy metal pollution index calculation in geochemistry assessment: a case study on Playa Las Petroleras.

This work is aimed to assess potential risk associated with the presence of metals and metalloids in soil at "Playa Las Petroleras" sector, located in Antofagasta (Chile). The zone under study has been affected by four oil spill events. This sector is located in an urban area by the sea. So, it has a great social and environmental relevance. The concentrations of 15 elements in soil samples were assessed, four of them presenting potential ecological risk: As, Co, Cu, and Pb. Nine pollution indices were applied to data: four single pollution indices and five integrated pollution indices to assess soil pollution. The single pollution indices show that the site bears potential ecological and environmental risk due to the presence of Cu, the site being classified as highly contaminated owing to a severe enrichment of this metal. For Co, all the indices allow classifying the site as little or uncontaminated, while the level of As and Pb pollution could be considered as ranging from uncontaminated to moderately contaminated. The integrated pollution indices show that average concentrations are highly contaminated mainly owing to the presence of Cu.

Characteristic curve modeling of plant species behavior in soils with heavy metals.

Many vegetal species can accumulate great amounts of metallic elements in their tissues. For this reason, they are called metal hyperaccumulators. An indicator of great interest in environmental sciences is the bioconcentration factor because it is recognized for establishing the potential accumulation of chemicals in organisms. Particularly in soil phytoremediation processes, it measures the capacity of a certain plant to capture metals, in terms of soil concentration. According to their behavior, four types of plants can be distinguished regarding soil concentration increase: indicator, excluder, accumulator, and hyperaccumulator. This study proposes a new model to categorize plants according to their behavior related to soil concentration increase, using several characteristic curves obtained from 1288 experimental measurements collected from different bibliographic sources. The metals analyzed were Cu, Fe, Pb, and Zn. The proposed model is obtained through linear regression and nonlinear transformations to model the expected behavior of plants in high concentration conditions. In particular, the basic equation of the model has three key components to represent the expected concentration in the plant root given the final soil concentration level, the type of species, and specific metal: a linear factor that determines the growth for low concentration values, an exponential factor that determines its decrease for high concentration values, and a logarithmic factor that limits the maximum value that can be reached in practice and influences the decay for high concentration values. After fitting the experimental data using linear regression, the proposed model has a 0.084 R2 determination coefficient and all of its parameters are considered significant. Furthermore, it shows that 60 of the 257 species assessed behave as accumulators and 10 of them as hyperaccumulators. The main contribution of this model is its ability to handle soils with high concentrations, where it would be hard for plants to achieve concentrations similar to or higher than the substrate containing them. Thus, the conventional criterion of the bioconcentration factor would incorrectly categorize a plant as an excluder. In contrast, this new model allows assessing plant effectiveness in a phytoremediation process of highly concentrated affected sites, such as mine tailings.

Distribution of potentially harmful elements in attic dust from the City of Coronel (Chile).

Attic dusts provide an indirect measure of airborne pollutants deposited in the urban environment. The objectives of this study are: (1) to determine the concentrations of As, Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sr, V and Zn in attic dust in the City of Coronel, (2) to evaluate the source apportionment of PHE and (3) to assess the risk of health effects from exposure in adults and children. In the City of Coronel, attic dust samples were collected in 19 houses. The concentrations of As, Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sr, V and Zn were measured in ICP-OES after Aqua Regia digestion of < 75 µm dust sample. The median (and the range) concentration (mg kg-1) of potentially harmful elements was: As 16 (7-72), Ba 154 (53-251), Cd 0.8 (0.25-14.5), Co 12, (8-22), Cr 38 (22-482), Cu 107 (44-1641), Mn 698 (364-1245), Ni 51 (24-1734), Pb 66 (18-393), Sr 131 (52-252), V 129 (57-376) and Zn 815 (107-9761). The exploratory data analysis shows that Ni, Cu, Cr, Zn, Pb and As distribution is dominated by anthropogenic sources and characterized by high extreme values. Principal component analysis shows four factors. One factor is geogenic, while the other three factors are associated with transport emissions and the industrial park. The resulting median of cumulative noncarcinogenic risk (HIs) value for attic dust was 3.49 for children. This is significant, as any value greater than one indicates an elevated risk.

Assessment and abatement of the eco-risk caused by mine spoils in the dry subtropical climate.

The highly rugged mountainous land topography of the Novorossiysk industrial agglomeration (NW Caucasus, Krasnodar Krai, Russia) and arid climate limit the restoration abilities of disturbed mine lands. Abandoned waste-rock dumps of a marl quarry occupy an area of ca. 150,000 m2 next to the cement plant, residential districts, and a commercial seaport. To assess the eco-risk, topsoil horizons of urban and mine-site Technosols and background Rendzinas were sampled and analyzed; measurements of particulate matter fractions PM1, PM2.5, PM4, and PM10 were conducted throughout the agglomeration. Fugitive dust emission from the unreclaimed marl dumps raises the PM2.5 content in the air by a factor of 2.68 on average. The high sorption capacity of the fine eluvium results in the accumulation of urban emissions by the dust and contributes to the subsequent soil pollution; the Cumulative Pollution Index of pedochemical anomalies reaches the high-risk level over the areas of up to 5 km2. Environmental threats caused by the mine dumps can be assessed more reliably by means of land zoning based on accumulated environmental damage indicators and the debris flow and waterspout risk calculation. To abate the technogenic impact caused by the mine spoils, reclamation actions must be taken including soil stabilization on sensitive sites by application of geosynthetic cover, hydroseeding of the mixture of soil improvers and seeds of herbaceous plants on the slopes, and anti-erosion plantation of cades (Juniperus oxycedrus L.) and smoke trees (Cotinus coggygria Scop.) at subhorizontal surfaces.

Potentially toxic elements concentrations in schoolyard soils in the city of Coronel, Chile.

Urban areas are constantly growing. By 2050, the urban world population, it is predicted to reach 6 billion. Being component of cities environment, urban soils have elevated levels of potentially toxic elements from anthropogenic action. The aims of this study are (1) to establish background levels of potentially toxic element in soils in the city of Coronel and (2) to assess the pollution and identify its origin. Samples (129 in total) were collected in Coronel, from 43 sites in schoolyards. Three samples were taken at each site: 0-10 cm, 10-20 cm and 150 cm depth. Principal component analysis (PCA), cluster analysis (CA) and depth ratios were applied to distinguish the origin of the contamination. The geoaccumulation index, contamination factor and the integrated pollution index were used to estimate the pollution. The median concentration of the chemical elements in 0-10 cm depth was Ba 38 mg kg-1; Co 15 mg kg-1; Cr 18 mg kg-1; Cu 22 mg kg-1; Mn 536 mg kg-1; Ni 35.5 mg kg-1; Pb 6 mg kg-1; V 94 mg kg-1; Zn 65 mg kg-1. Principal component analysis and CA suggested that Co, Ni and Mn were mainly derived from geogenic origin, while Ba, Cr, Cu, Pb, V and Zn from anthropic origin. Contamination factor indicated that some soil samples were classified as considerable contaminated to very highly contaminated by Ba, Pb, Zn and V.

On the ordered nature of redistribution of technogenic elements in undisturbed elementary landscape-geochemical systems of the temperate zone on the example of the Chernobyl 137Cs fallout.

The study is aimed at identifying patterns in distribution of pollutants in the elementary landscape-geochemical systems (ELGS) of the temperate zone. The study used 137Cs as a tracer, which allows a highly detailed analysis of the nature of the heterogeneity of secondary migration in the toposequence: summit-slope-closing depression, treated as the elementary landscape-geochemical system. The study site was located in the Bryansk region in the Chernobyl abandoned area with an initial level of 137Cs contamination exceeding 1480 kBq/m2 (40 Ci/km2). An original technique of repeated 137Cs measurements along cross-sections accompanied by topographic survey and soil cores sampling has been applied. The obtained results showed a complete absence of constant increase of 137Cs concentration downslope but revealed a steady regular variability of 137Cs activity of a cyclical type. Given uniformity of the initial 137Cs fallout within a small-sized plot, variation of 137Cs due to its secondary distribution in ELGS was 2-2.7-fold according to field gamma-spectrometry data which corresponded to the radionuclide contamination density of the top 20-cm layer of the soil containing 96-99% of the total radionuclide amount (correlation between the parameters equaled to r0.01 = 0.782, n = 20). A specifically regular structure obviously formed under the set of radionuclide water migration processes seems to be inherent in all systems of the studied type. The results obtained are believed to be of both theoretical and practical importance, since they can contribute to making decisions on the precise monitoring of zones of technogenic accumulation, as well as solving fundamental problems of soil formation and its restoration after technogenic pollution.

Uptake of potentially toxic elements by edible plants in experimental mining Technosols: preliminary assessment.

A study was carried out to evaluate the absorption of potentially toxic elements from mining Technosols by three types of vegetable plants (broccoli (Brassica oleracea var. italica), lettuce (Lactuca sativa) and onion (Allium cepa)), the different parts of which are intended for human and farm animal consumption (leaves, roots, edible parts). The preliminary results obtained highlight the importance of the design of the mining Technosols used for agricultural purposes, obtained from soils and sediments of mining origin and amended with residues of high calcium carbonate concentrations (limestone filler and construction and demolition wastes). The experiment was carried out in a greenhouse, and the total metal(loid)s concentration (As, Pb, Cd, Cu, Fe, Mn and Zn) of the soil, rhizosphere, aqueous leachates and plant samples was monitored, the translocation and bioconcentration factors (TF and BCF, respectively) being calculated. The characterization of the soils included a mobilization study in media simulating different environmental conditions that can affect these soils and predicting the differences in behavior of each Technosol. The results obtained showed that the levels of potentially toxic elements present in the cultivated species are within the range of values mentioned in the literature when they were cultivated in soils with calcareous amendments. However, when the plants were grown in contaminated soils, the potentially toxic elements levels varied greatly according to the species, being higher in onions than in lettuce. Experiments with the use of lime filler or construction and demolition wastes for soil remediation result in crops that, in principle, do not present health risks and are similar in development to those grown on non-contaminated soil.