Toxic Metals In Soil Research Articles

Source-oriented stochastic health risk assessment of toxic metals in soil via a hybrid model and Monte Carlo simulation

Toxic metal contamination in soils poses significant hazards to the environment and human health; thus, quantitative assessment of the sources and risks of metal contaminants are urgently needed. A hybrid model that integrates the positive matrix factorization (PMF) and random forest (RF) methods was proposed to quantify the sources of toxic metals in soils by combining diverse environmental variables (source proxies) in this study. In addition, a health risk assessment and Monte Carlo simulations were integrated to estimate the source-oriented stochastic health risk. The results suggested that, except for Ni, which exhibited moderate contamination, other toxic metals (As, Cd, Cr, Hg and Pb) presented slight contamination. Four sources (agricultural activities loaded heavily by As, atmospheric deposition loaded heavily by Hg and Pb, natural sources and mining activities loaded heavily by Cr and Ni, and industrial activities loaded heavily by Cd) were defined and explained 23.44 %, 26.65 %, 30.13 % and 19.78 % of the total variance in toxic metals, respectively. The principal route of exposure (i.e., ingestion), the population at highest risk (i.e., children), and the most hazard-inducing metals (i.e., As and Cr) were determined. Agricultural activities and the combination of natural sources and mining activities demonstrated certain degrees of noncarcinogenic risk to children, with exceedance ratios of 2.20 % and 2.56 %, respectively. Additionally, the combination of natural sources and mining activities demonstrated probabilities for significant carcinogenic risk to adults and children of 0.59 % and 3.76 %, respectively. To reduce the health risks of toxic metals in soils and to protect food and ecological safety, strict regulations should be established to control the discharge of waste from mining and agricultural activities.

Industrial Pollution in Patna City : Physico-Chemical Analysis of Effluents and Their Effects on Water and Soil

Industrial pollution is a significant concern in Patna City, with rapid urbanization and industrial growth contributing to the degradation of natural resources. This study focuses on the physico-chemical analysis of industrial effluents and their effects on the water and soil quality in and around Patna. Effluents from various industries, including textile, sugar, rice mills, and small-scale manufacturing units, are released into nearby water bodies and soils, posing serious environmental risks. The research aims to assess the levels of pollutants by analysing key physico-chemical parameters such as pH, total dissolved solids (TDS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), heavy metals (lead, chromium, cadmium), and organic contaminants in industrial effluents. Samples were collected from various locations near industrial zones and water bodies. The study also evaluated the impact of these pollutants on soil and groundwater quality. It was found that prolonged exposure to industrial effluents led to the accumulation of toxic metals in soil, reducing its fertility and altering its structure. Additionally, groundwater sources were contaminated with hazardous chemicals, making them unfit for drinking and irrigation purposes. The implementation of advanced treatment technologies and sustainable industrial practices is crucial for safeguarding the environment and public health in Patna City.

Spatial distribution and factors influencing the accumulation of toxic metals in soils in mountain agroecosystems, Rio De Janeiro, Brazil.

The concentrations of toxic metals (TM) were analyzed in 498 samples of agricultural soils used for intensive vegetable cultivation in the watershed of Barracão dos Mendes, Brazil. The goal of this study was to characterize the distribution of these elements and the main natural and anthropogenic factors affecting their accumulation. In general, the average concentrations of TM were higher than the reference quality values for cultivated soils in the region, with the exception of Cr, Co, Ni and Mn, and the average concentration of Cd was ten times greater. Three sources of variation in the distribution of TM concentrations were identified: one related to topographic relief, another related to lithology, and one related to the massive use of agrochemicals. These factors contributed to TM accumulation in the soil; moreover, the transport of toxic metal-enriched clay by runoff resulted in higher concentrations of these elements in the lower parts of the slope. The long-term application of massive amounts of fertilizers and pesticides resulted in the accumulation of Cr, Cu, Zn, Ni, Pb and Cd in the vegetable cultivation soils and promoted the enrichment of macronutrients, mainly P and K. Moreover, the spatial distribution of TM in the agricultural soils of this mountain agroecosystem was affected by intensive vegetable cultivation, which altered the natural TM distribution dynamics determined by variations in topographic relief and lithology. In intensive cultivation areas, the TM distribution was also influenced by soil management practices such as tillage along the slope direction and massive mineral and organic fertilization.

Heavy Metal Pollutants Or Contaminant In Soil Samples Obtained From Wash Boreholes Within Pantisawa, Yorro L.G.A. Of Taraba State

The problem of environmental pollution and its compartments due to an increase in contamination as a result of the accumulation of heavy metals and microorganisms from soil has raised wide-spread of concerns in different parts of the nations and this has compromised the ability of the environments to foster life and render them an intrinsic value. Hence the study aimed to ascertain the level of environmental pollution in soil from wash borehole within Pantisawa Yorro Local Government Area of Taraba State, Nigeria. A total of 45 samples for soil were collected aseptically from the five different zones (Pantisawa Main Market YM, Kapazang YG, Dola YD, Kallau YK and Zabi YZ) of Pantisawa. The levels of trace metals in soil samples were determined using Atomic Absorption Spectroscopy (AAS) PG-990. The results were analyzed using SPSS Version 20. The soil samples result for these metals revealed that iron concentration was between 3000-4010mg/kg most especially for site SD which is higher than all other elements analyzed. Zinc ranges from 2.54-6800mg/kg which is above the standard as prescribed by WHO and FEPA in soil and also exceeded the dutch target values of (Zn: 50mg/kg and Cu: 30mg/kg) in some of the sampling sites. Nickel was between 8.47-19.09 mg/kg in soil samples, this is below the toxicity threshold limit of 35mg/kg for safe environment as stated by WHO. Arsenic ranges from 53.06mg/kg–141mg/kg, which is higher than the admissible limit of 50mg/kg in soil recommended by UNEP. The order of all the metal concentration in the areas was Fe>Zn>Mn>As>Pb>Cu>Mn>Co and Cd respectively. Based on this study, the high concentration of the metals such as Zn, As, Cd, Pb, and Co in some of these sites most especially SK, SM and SD within Pantisawa revealed that some of the soil samples collected from these areas were contaminated with heavy metal pollutants which may have serious health risk to the people using it for various activities. The higher concentrations of these toxic metals in soils need to be monitored regularly for heavy metal enrichment.

Determination of the levels of selected essential and toxic metals in soil collected from the flower farm in Roshara Roses PLC (Bishoftu) of Ethiopia and assessment of associated human health risks

The overuse of pesticides and fertilizers to grow high-quality roses unintentionally introduces heavy metals into the soil which is detrimental to the human health. Thus, the aim of the current study is to examine the concentrations of the essential (Ca, Mg, Zn, Fe, Cu, Fe, Mn and Ni) and toxic metals (Cd and Pb) in the soil samples from the flower farm using Flame atomic absorption spectrometry (FAAS) and to assess the risk that heavy metals pose to human health. To obtain an optimum condition for the wet digestion of soil samples, the volume ratio of reagents, reflux time and temperature were optimized. The concentrations of Ca, Fe, Mn, Mg, Zn, Cr, Ni, Cu were found to be 3468, 4926, 450, 255, 74, 70,48.5 and 25 and 2150, 4862,472, 241, 71, 58, 37 and 12.5 mg/kg for the soil samples collected from the flower farm and road side, respectively. Cadmium and lead were not detected in the studied soil samples. Statistical analysis of variance (ANOVA) showed the concentrations of Ca and Cu in the two soil samples are significantly different. Correlation analysis showed there was strong positive association for Fe with Zn, Cr and Ni, Mg with Ca, Cu, Ni and Cr, Zn with Cr and Cu and Ni with (Cu, Zn and Cr). Values of hazard quotient (HQ) and hazard index (HI) for the heavy metals under the study in the all exposure pathways are below 1.0 indicating that none of them could be harmful to human health.

Concentrations and Health Risk Valuation of Possibly Toxic Metals in Soil and Sediment in Parts of Ona River, Ibadan, Nigeria

The accumulation of contaminants in the soils and sediments may negatively affects people within the vicinity of Ona River and increase potential of human health risk. This study appraised the concentration status, probable origins and human health risks of some possibly toxic elements (Fe, Cu, Zn, Mn, Pb and Cd) in the riverbank soils (RBK) and riverbed sediments (RBS) of Ona River section bordering residential community in Ibadan, Southwest Nigeria. Therefore, six composite samples of RBK and RBD were analyzed for heavy metals using atomic absorption spectrophotometry (AAS). Enrichment factor (EF) and quantification of contamination (QoC) are used to examine potential origins of tested metals. Furthermore, hazard index (HI) and total cancer risk (TCR) have been utilized to evaluate the extent of non-carcinogenic and cancer risks of studied metals to inhabitants of the study site. The results of metal contamination assessment revealed low concentration <1.0 mg/kg for each analyzed metal in both RBK and RBD while EF and QoC advocate lithogenic origins of assessed metals with little or none anthropogenic inputs in both studied soils and sediments. The computed HI values were lower than 1.0 and thus no adversative health effects on adults and children via ingestion, skin contact and inhalation routes. The CR computation exposed that adults and children are at growing risk of developing cancer over a lifetime when exposed to RBK and RBD via ingestion and dermal pathways. Cadmium contributed largely to TCRs among the assessed metals. The study indicates the inevitability of initiating actions that reduce exposure of residents to nearby soil and sediment and safeguard their health, particularly the children.

Potential of Plant Based Metallophytes for Phytoremediation in Agriculture

Metallophytes are the unique group of plants that have evolved to thrive in metal rich environments and have drawn plenty of attention. Remediating heavy metal contaminated places with plants is an effective choice due to phytoremediation, an environmentally friendly method that uses plants to mitigate the pollution. Metallophytes are ideal options for phytoremediation applications due to their inherent traits such as hyper-accumulation, efficient metal absorption and tolerance mechanisms impacting both the plant and soil. These plants absorb and translocate heavy metals, detoxifying the soil while accumulating them in tissues. This reduces metal toxicity in soil and holds potential for resources recovery. The role of metallophytes in phytoremediation is analysed in this review with particular focus given to their ways of metal absorption, translocation and detoxification. Metallophytes have high metal tolerance and accumulation capacities due to their unique physiological and biochemical adaptations including enhanced metal sequestration in vacuoles, metal chelation by phytochelatins and activation of anti-oxidant defence systems. This review also highlights the significance of metallophytes in enhancing the soil health, reducing metal bioavailability, and promoting the ecological sustainability as well as their potential for restoring contaminated ecosystems. Utilizing the unique capabilities of metallophytes obtained from plants possesses enormous possibilities to minimise the negative effects of heavy metal pollution, protect ecosystems, and promote sustainable development for future generations. Eventually, it outlines future research approaches that aim to enhance metallophytes based phytoremediation strategies, widen their implementation and include them in holistic approaches for environmental restoration and sustainable land management.

Hormonal profile changes under the influence of environmental factors in children residing in the Aral environmental disaster region

BACKGROUND: Since the mid 20th century, the Southern Aral Sea Region is notorious as a region of ecological disaster, where anthropogenic influence led to the desiccation of the Aral Sea. Aridization of these territories is the cause of accumulation of endocrine disrupting chemicals — pesticides and toxic metals in soil and water.
 AIM: The aim of this study was to assess the changes in hormonal profile under the influence of environmental factors in prepubertal children living at different distances from the epicenter of the Aral ecological disaster.
 MATERIALS AND METHODS: The study included 58 male children aged 11–13 years. All children from birth lived in two regions of the Aral Sea Region and were divided into two groups depending on their place of residence. The group “North” (unfavorable conditions) consisted of 27 children from Muynak, Kungrad, Karauzyak, Takhtakupyr districts. The “Nukus” group (relatively favorable conditions) included 31 volunteers from Nukus city. All children were determined the concentration of IGF-1 — Insulin-like growth factor 1, GH — growth gormone, TT — total testosterone, E2 — estradiol, FSH — follicle-stimulating hormone, LH — luteinizing hormone, TSH — thyroid-stimulating hormone, TT3 — total triiodothyronine in blood sample. The statistical significance of the differences of the mentioned hormones in children from the “North” and “Nukus” groups was checked using the Mann–Whitney test.
 RESULTS: This analysis revealed statistically significantly higher values of TT, FSH and LH in children from the “Nukus” group compared to their peers from the “North” group. The concentrations of IGF-1, GH, E2, TTG and T3 in blood plasma in volunteers from both groups were not statistically significantly different.
 CONCLUSIONS: The environment of the Aral ecological disaster region with increased content of organochlorine compounds, pesticides and heavy metals changes the endocrine status in local prepubertal children. This is expressed in a moderate decrease in the activity of androgens (but not estrogens) and gonadotropic hormones. This research work can be considered as a pilot study, which determines the need for further monitoring of endocrine disorders in children and adults living in negative environmental conditions.

Organic farming in the improvement of soil health and productivity of tea cultivation: A pilot study

AbstractThe sub‐mountainous tea gardens of the Dooars region of West Bengal, which contribute approximately 25% of the national tea yield, are constantly fighting with diminishing soil fertility. Inorganic alternatives like chemical fertilizers can provide easier yet short‐term solutions, as their prolonged and indiscriminate usage leaches the soil, devouring its productivity, increasing the soil's heavy metal contents, and subsequently accumulating those heavy metals in leaves. A plausible substitution in this scenario could be the use of organic alternatives like composting or biofertilizer. Although references to such alternative means are found in the literature, a holistic approach targeting plant growth promotion along with mitigating soil metal toxicity is lacking. Keeping this background in mind, this pilot study was designed to optimize the dosage of novel biofertilizers (using resident and alien flora) that can reduce heavy metal loads and residual toxicity in soil, thereby improving overall soil health and tea production. Two potential metallophilic plant growth‐promoting strains of Bacillus sp. (previously reported) were selected and applied to potted tea plants of two different varieties of tea: TV9 and TV25. Among the two modes of treatment tested: solid treatment (compost amended with bacterial culture) and liquid treatment (cell pellets mixed in water suspension), the water suspension‐based direct application of resident soil bacteria showed the highest physiological growth with reduced metal toxicity. Based on physiological data and physico‐chemical data collected, it was observed that direct application of bacteria showed better results in both plant and soil health improvement in comparison to regular compost amended with beneficial microflora. Therefore, this small‐scale pilot study aimed to optimize the dosage and mode of application of novel biofertilizers for improved soil and plant health.

Quantitative heterogeneous source apportionment of toxic metals through a hybrid method in spatial random fields

Toxic metals in soils pose hazards to food security and human health. Accurate source apportionment provides foundation for pollution prevention. In this study, a novel hybrid method that combines positive matrix factorization, Bayesian maximum entropy and integrative predictability criterion is proposed to provide a new perspective for exploring the heterogeneity of pollution sources in spatial random fields. The results suggest that Cd, As and Cu are the predominant pollutants, with exceedance rates of 27%, 12% and 11%, respectively. The new method demonstrates superiority in predicting toxic metals when combined major and all sources as auxiliary information., with the improvements of 44% and 46%, respectively, Although the major sources identified with the hybrid method are the primary contributors to the accumulation of toxic metals (e.g. coal combustion for Hg, traffic emission for Pb and Zn, industrial activities for As, agricultural activities for Cd and Cu and natural sources for Cr and Ni), the impact of nonmajor sources on toxic metal sin specific regions should not be ignored (e.g. industrial activities on Ni, Pb and Zn in the north and natural sources on Cd, Cu, As, Pb and Zn in the south). For better pollution control, specific local sources should be considered.

Resource co-limitation of community biomass but not structure of an alpine grassland.

Anthropogenic environmental changes are influencing the structure and function of many ecological communities, but their underlying mechanisms are often poorly understood. We conducted a seven-year field experiment to explore the ecological consequences of nitrogen (N) and phosphorous (P) enrichment in a high-altitude Tibetan alpine grassland. We found that the enrichment of both N and P, but not either alone, increased plant above- and below-ground biomass. By contrast, N, but not P, enrichment reduced species richness, and altered plant phylogenetic diversity and structure. Whereas plant species loss and changes in phylogenetic structure were mainly driven by higher soil manganese levels under N addition, they were mainly driven by increased plant belowground biomass under the addition of both N and P. Our study highlights resource co-limitation of community biomass but not structure of the study grassland, while also identifying soil metal toxicity and belowground competition as important mechanisms driving community changes following nutrient amendment.

Prediction of Cu(II) retention, sorption mechanism and biochar effect in tropical soil

The sorption behavior of potentially toxic metals in soils influences their spread to other environmental compartments and their bioavailability to life forms. The present study evaluated the sorption of Cu(II) ions in two representative soils from Yala and Tindinyo regions along River Yala in Lake Victoria basin, Kenya. The sorption experiments were carried out in single component solution systems using the batch technique. The equilibrium data was modeled using Henry’s isotherm model and four two-parameter isotherm models. Freundlich and bi-phasic Henry’s isotherm models best described the data, while both negative constants for Langmuir and Elovich necessitated rejection of the models. The y-intercept values for Henry’s monophasic fitting were negative, but the corresponding soil solution values of 0.43 μg/mL and 0.45 μg/mL for the Yala and Tindinyo soils, respectively, were taken as the background Cu(II) solution levels. We propose that in cases where the y-intercepts are negative, the bi-phasic Henry’s model can be used to predict a soil’s critical retention limit for a given pollutant, while the corresponding soil solution amount gives the permissible level in the soil solution. Using bi-phasic Henry’s model, the critical Cu(II) retention limits were determined as 300.11 μg/g and 301.48 μg/g for Yala and Tindinyo soils, respectively. The corresponding soil solution amounts were 3.47 μg/mL and 3.36 μg/mL for Yala and Tindinyo soils, respectively. The background and equilibrium soil solutions were below and above the WHO limit of 2 μg/mL for drinking water, respectively, while the sorbed amount was above the WHO limit of 36 μg/g soil. These findings indicate that a contaminant in soil may not pose any toxicity risk unless its concentration exceeds the critical retention limit, and that a pollutant’s toxicity is dependent on the soil solution amount rather than the total amount in soil. Dissolved organic carbon was more dominant than clay fractions in influencing the degree of sorption in both soils. Surface complexation between Cu(II) ions and carboxylic functional groups is hypothesized as a plausible sorption mechanism. Immobilization of Cu(II) in soil was significantly increased by amendment with fish-scales-derived biochar which, therefore, has promising potential application in mitigating environmental contamination by metals.

Processing toxic metal source proxies appropriately for better spatial heterogeneity source apportionment

Soil toxic metals have strong spatial heterogeneity, and their sources vary among regions. Thus, this study integrated the Catreg and geographically weighted regression (GWR) models to quantitatively extract the main source proxies (numerical and categorical variables were analyzed simultaneously) for different toxic metals and analyze the spatial heterogeneity of the distributions of these sources. Pb, Cd and Hg were the predominant toxic metals in soil. Of the samples with Pb, Cd and Hg, 84.12 %, 68.03 % and 41.57 % exceeded the background values, and 5.36 %, 6.42 % and 5.43 % were moderately contaminated according to the geoaccmulation index, respectively. Industrial activities, with relative importance values of 17.82 %, 31.54 % and 26.51 % for Cd, Hg and Pb, respectively, were the predominant source of these metals especially, in their high-content cluster areas (central urban areas). Soil available phosphorus was another important factor (relative importance values of 13.03 %, 13.41 % and 25.55 % for Cd, Hg and Pb, respectively), and agricultural activities (especially the overuse of phosphoric fertilizers) were identified as an anthropogenic source of these toxic metals. Soil parent material had the greatest influence on As and Cr, with relative importance values of 19.88 % and 19.09 %, respectively, especially in their high-content accumulation area (the eastern coastal area), indicating that these toxic metals mainly come from natural sources. Slope had important impacts on toxic metal accumulation (relative importance values of 17.48 %, 21.22 %, 12.40 % and 16.13 % for Cd, Hg, Cr and As, respectively) by influencing industrial distribution and pollutant migration. By changing the soil adsorption capacity, soil organic matter (explaining 13.01 % of Pb) and soil pH (explaining 14.58 % of As and 12.40 % of Cr) strongly influenced toxic metal accumulation. This study highlights the benefits of the integrated Catreg-GWR model for analyzing multiple spatially heterogeneous environmental data types (numerical and categorical variables), providing a potential foundation for local pollution prevention.

Pig manure biochar for contaminated soil management: nutrient release, toxic metal immobilization, and Chinese cabbage cultivation

Pig manure could be an effective fertilizer source for soil, but with high concentrations of xic elements. It has been shown that the pyrolysis method could largely reduce the environmental risk of pig manure. However, the comprehensive analysis of both toxic metals immobilization effect and environmental risk of pig manure biochar applied as a soil amendment is rarely addressed. To address the knowledge gap, this study was carried out with pig manure (PM) and pig manure biochar (PMB). The PM was pyrolyzed at 450 ℃ and 700 ℃, the corresponding biochar was abbreviated as PMB450 and PMB700, respectively. The PM and PMB were applied in a pot experiment growing Chinese cabbage (Brassica rape L. ssp. Pekinensis) with clay-loam paddy soil. The application rates of PM were set at 0.5% (S), 2% (L), 4% (M) and 6% (H). With the equivalent mass principle, PMB450 and PMB700 were applied at 0.23% (S), 0.92% (L), 1.84% (M), 2.76% (H), and 0.192% (S), 0.7% (L), 1.4% (M), 2.1% (H), respectively. Parameters of Chinese cabbage biomass and quality, total and available concentrations of toxic metals in soil, and soil chemical properties were systemically measured. The main results of this study showed that compared with PM, PMB700 was more effective than PMB450, which induced the highest reductions of Cu, Zn, Pb, and Cd contents in cabbage by 62.6%, 73.0%, 43.9%, and 74.3%, respectively. Both PM and PMB increased the total contents of metals (Cu, Zn, Pb, and Cd) in soil, and PMB decreased the mobility of Cu, Zn, Pb, and Cd at high application rates (≥2%). Treatment with H-PMB700 reduced CaCl2 extractable Cu, Zn, Pb, and Cd by 70.0%, 71.6%, 23.3%, and 15.9%, respectively. For Cu, Zn, Pb, and Cd fractions with BCR extraction, PMB treatments, especially PMB700, were more effective than PM in decreasing the available fractions (F1 +F2 +F3) at high application rates (≥2%). Overall, pyrolysis with high temperature (e.g., 700 ℃) could significantly stabilize the toxic elements in PM and enhance PM’s effect on toxic metals immobilization. The marked effects of PMB700 on toxic metal immobilization and cabbage quality improvement might be attributed to high ash contents and liming effect.

Utilization of Biochar Alone and in Combination with Compost for Removal of Potentially Toxic Metals Accumulated in Soils Associated with Land-use Patterns

Background: Potentially toxic metals in soils are a threat to food security and human health because it enters the food chain through crop uptake. Hence, it is critical to understand the levels of potentially toxic metals in soils due to agricultural land use patterns and the approach to remove them from the soil. Objective: This review discussed the effect of different land-use patterns on heavy metal accumulation and their removal using biochar. Methods: A desktop review employing preferred reporting items for systematic review and meta-analysis was used to analyse information from peer-reviewed papers including journal articles, books, thesis, and reports. Results: It was shown that potentially toxic metals mainly found in the soil include arsenic (As), copper (Cu), cadmium (Cd), zinc (Zn), chromium (Cr), cobalt (Co), nickel (Ni), antimony (Sb), mercury, thorium (Th), lead, silicon (Si), and selenium (Se). The sources of these potentially toxic metals accumulation in soils were the application of organic and inorganic fertilizers, irrigation, use of pesticides and weedicides, and atmospheric deposition. However, different land-use patterns (greenhouse field, vegetable field soils, forest field, and maize field soil) had a significant accumulation of heavy metals (Cr, Ni, Cu, As, Cd, and Zn) due to increasing crop yield after the use of fertilizers and pesticides. Biochar was found to be effective in the removal of 18 to 40% of these potentially toxic metals from the soil. The mechanisms of removal included precipitation, physical sorption, complexation, ion exchange, and electrostatic interaction. Conclusion: Biochar applied alone or with compost is highly stable to remove heavy metals accumulated in soils due to land use patterns.

Critical source apportionment and source-oriented risk-based evaluation of toxic metals in soils and rice around brick kiln area

Critical source apportionment and source-oriented risk-based evaluation of toxic metals in soils and rice around brick kiln area

Iron nutrition in agriculture: From synthetic chelates to biochelates

Iron (Fe) is an essential micronutrient for plant growth and productivity and, among other micronutrients, is the one required in higher amounts. In most soils, Fe occurs at relatively high concentrations; nevertheless, in calcareous soils, Fe bioavailability can be very limited, thus leading plants to develop Fe deficiency symptoms. At present, Fe fertilization still represents the most frequent approach adopted in agriculture to prevent or remediate Fe chlorosis. For soil applications, Fe fertilizers are based on Fe chelated with aminocarboxylate synthetic ligands (e.g. HEDTA, EDTA, DTPA, EDDHA), which are effective in maintaining Fe in the soil solution, even in alkaline soils, and thus in increasing its bioavailability for plant uptake. Nevertheless, Fe-aminocarboxylate complexes presents some limitations, related for instance to pH-dependent effectiveness, stability, persistence in the environment and ligand exchange reactions. In this context, vegetal-derived protein hydrolysates might represent good sources of biochelating ligands for developing innovative Fe fertilizers for sustainable agriculture. Protein hydrolysates are composed by small peptides, which, on one hand, can chelate Fe via amino acid side chains, carboxylate groups of C-termini, amine groups of N-termini and N atoms of amide groups of the peptide backbone, whilst, on the other hand, small peptides can also play a signaling role, triggering the acquisition of nutrient and morphogenetic processes in plants. The present paper reviews the current state of knowledge on traditional Fe fertilizers and, on the other side, explores the possible advantages in the application of biochelates as innovative Fe fertilizers. To further corroborate the hypothesis, three experimental trials have been carried out on three horticultural crops (cucumber, tomato, and strawberry) using a Fe-biochelate as Fe source and comparing it with the widely used traditional synthetic chelate Fe-EDDHA. The results in the three crops clearly show that Fe-biochelate is, at least, as efficient as Fe-EDDHA as source of micronutrient, even under circumneutral (pH 6.0) and alkaline conditions (pH 8.0), thus proving that Fe-biochelates can be promising alternatives to synthetic Fe chelates for the Fe nutrition management of crops. Considering the potential drawbacks of synthetic chelates (e.g., leachability, persistence, remobilization of toxic metals in soil), these findings might contribute enhancing the agriculture sustainability. In addition, Fe-biochelate could also find an application in soilless cultivation systems as an alternative to synthetic Fe chelates for Fe enrichment of edible plant tissues (biofortification), increasing their nutritional value.

Quantitative analysis of heavy metals in soilviahierarchical deep neural networks with X-ray fluorescence spectroscopy

Potentially toxic metals in soils are accurately predicted using hierarchical depth neural networks by X-ray fluorescence spectroscopy.

The ecological risk of contamination with toxic metals in soils around the trepça complex, the Kosovo thermal power plants, and a new co ferronickeli complex

The ecological risk of contamination with toxic metals in soils around the trepça complex, the Kosovo thermal power plants, and a new co ferronickeli complex

Sources, Indicators, and Assessment of Soil Contamination by Potentially Toxic Metals

Soil pollution caused by potentially toxic metals has become a worldwide environmental issue. Geogenic processes and anthropogenic activities are two important sources of soil pollution. Soils may inherit toxic metals from parent materials; however, soil pollution mostly results from industrial and agricultural activities. Contamination by metals can be indicated by the changes in chemical, biochemical, and microbial properties of soils and plant responses. The total concentration of toxic metals in soil is still the most widely used indicator for risk assessment although extractable amounts have been reported to be more closely related to plant uptake. Several models have been proposed for assessing soil contamination by toxic metals, but none of them are commonly accepted for application to a wide range of soils. This review paper highlights how toxic metal contamination negatively affects soil and environmental quality, impacts food quality and security, and poses a threat to human health. Further research is needed to not only improve soil contamination diagnosis, modeling, and regulatory standards but also for remediation efficiency.