Heavy Metals In Plants Research Articles

Micro-Evolutionary Processes in Armeria maritima at Metalliferous Sites.

Tolerance to heavy metals in plants is a model process used to study adaptations to extremely unfavorable environments. One species capable of colonizing areas with high contents of heavy metals is Armeria maritima (Mill.) Wild. A. maritima plants growing in metalliferous areas differ in their morphological features and tolerance levels to heavy metals compared to individuals of the same species growing in non-metalliferous areas. The A. maritima adaptations to heavy metals occur at the organismal, tissue, and cellular levels (e.g., the retention of metals in roots, enrichment of the oldest leaves with metals, accumulation of metals in trichomes, and excretion of metals by salt glands of leaf epidermis). This species also undergoes physiological and biochemical adaptations (e.g., the accumulation of metals in vacuoles of the root's tannic cells and secretion of such compounds as glutathione, organic acids, or HSP17). This work reviews the current knowledge on A. maritima adaptations to heavy metals occurring in zinc-lead waste heaps and the species' genetic variation from exposure to such habitats. A. maritima is an excellent example of microevolution processes in plants inhabiting anthropogenically changed areas.

Risk Assessment of Heavy Metals in Soils from Four Different Industrial Plants in a Medium-Sized City in North China.

Laboratory experiments were carried out to analyze 39 soil samples collected from four industrial areas in Xuzhou City using inductively coupled plasma mass spectrometry and atomic fluorescence spectrometry. The descriptive statistics of heavy metals (HMs) in the soil profiles showed that the HM content at three depths was highly variable, and most coefficients of variation (CVs) showed moderate variability. The enrichment of Cd at all depths exceeded the risk screening value, and Cd pollution occurred in four plants. The enrichment of the other HMs at three depths was mainly concentrated in the pharmaceutical plant A and chemical plant C. It was found that the different HMs had different vertical distribution characteristics. For the different industrial plants, the raw materials and products not only made the spatial distribution characteristics of the HMs different, but also caused the HM types and contents to differ. The average single pollution indices of Cd in plant A, iron-steel plant B, and plant C indicated a slight pollution level. The other seven HMs in A, B, and C and all HMs in chemical plant D belonged to the safe category. The mean values of the Nemerow pollution index in the four industrial plants belonged to the warning category. The analysis showed that none of the HMs posed potential noncarcinogenic health risks, and only the carcinogenic health risks of Cr in plants A and C were unacceptable. The carcinogenic effect of Cr through the inhalation intake of resuspended soil particulates and that of Cd, Ni, and As via direct oral ingestion were the main exposure pathways.

The content of heavy metals in the vegetative mass of pumpkin plants when applied by the sprinkling method

Obtaining high yields of agricultural plants with their proper quality on soils contaminated with heavy metals is of the utmost importance for modern farmers of the Kuban. The purpose of the research is to study the accumulation of heavy metals in the vegetative organs of pumpkin plants, depending on the properties of the soil and the physical and chemical properties of pollutants. The tasks are to determine the influence of the physical and chemical properties of the soil on the accumulation of heavy metals in the vegetative part of the studied plants; to determine the influence of the chemical properties of heavy metals on their accumulation in the vegetative part of the studied plants. By the method of field research, the accumulation of heavy metals in the vegetative mass of pumpkin, Mramornaya variety, when applied by sprinkling method, depending on the physico-chemical properties of the soil, has been studied. Heavy metals in plants are determined by the AAS method. It has been found that when growing the studied plant on a rain-fed plot of meadow-chernozem soil, copper and cadmium accumulated in the foliage less than in the soil of rice check, respectively 2.2 and 4.9 times. The studied heavy metals had a depressing effect on the biometric parameters of the pumpkin. On the experimental plots of meadow-chernozem soil of the bogarny plot and the soil of the rice check, there was a decrease in the studied biometric parameters compared with the control. Moreover, on the meadow-chernozem soil of the rice check, this decrease was more intense. Under the influence of heavy metals and soil properties, the yield of the studied plant decreased: for the first variant it was 24.0 t/ha, for the second – 8.2 t/ha. When growing Mramornaya pumpkin variety on meadow-chernozem soil, a rain-fed area of cadmium accumulated more than copper by 16.0 times, on meadow-chernozem soil of rice check, this difference was 47.0 times. One of the reasons for this difference in the accumulation of heavy metals is their physiological role for the plant under study.

Enrichments, Migrations, and Conversions of Heavy Metal in the Soil/Sediment-Plant System Towards the Lake in Typical Poyang Lake Wetland

A large area of periodic water-level-fluctuating zone (WLFZ) in the Poyang Lake, regulated by a special hydrologic rhythm, was deposited with significant amounts of nutrients and pollutants. In this study, the WLFZ located in a typical estuarine wetland was chosen and sampling transects were arranged according to different vegetation types towards the lake. Soil/sediment and dominant plant (different tissues) samples were collected, and contents and enrichment levels of heavy metals (Cr, Ni, Cu, Zn, As, Cd, Sb, and Pb) in these samples were analyzed. The migrations and conversions of heavy metal in the soil/sediment-plant system were evaluated, and driving environmental factors were explored. The results indicated that the contents of heavy metal in the soil/sediment presented an obvious single-peak distribution towards the lake, that is, the seasonally flooded zone was identified as the main deposited zone of heavy metals. There was a high enrichment level of Cu, Pb, and Sb in the soil/sediment from the WLFZ, and significant Cu and Sb pollution was identified (EF>5). The results from the potential ecological risk evaluation (RI) indicated that the ecological risk of the seasonally flooded zone was significantly higher than that in the flooded and unflooded zones, being at a low ecological risk (70 ≤ RI<140). There was no obvious spatial distribution of heavy metal contents in the dominant plant towards the lake, whereas significant seasonal differences were detected. The levels of heavy metals in plants at the growth phase (April) were higher compared to those at the other sampling times. The tissue distributions of heavy metal content basically followed the sequence of soil/sediment>root ≥ above-ground part, except for in Cd and Sb. The Cd content in the roots was significantly higher than that in the sediment/soil, and the Sb concentration was not significantly different among the three tissues. The bio-enrichment coefficient (BAF) and transfer factor (TF) of heavy metal in the dominant plant towards the lake did not show an obvious spatial pattern, and BAF and TF of heavy metals in the Artemisia capillaris Thunb. was higher than those in other dominant plants. The RDA revealed that pH, organic matter, plant height, and Fe-Mn oxides were the key environmental factors driving the migrations of heavy metals in the soil/sediment-plant system. These results will provide scientific basis and theoretical support for the biodiversity conservation and heavy metal pollution prevention and management in wetlands of the Poyang Lake.

РЕЗУЛЬТАТЫ МОНИТОРИНГА СОДЕРЖАНИЯ ТЯЖЕЛЫХ МЕТАЛЛОВ В ПОЧВЕ, РАСТЕНИЯХ И СНЕЖНОМ ПОКРОВЕ ВБЛИЗИ АВТОМОБИЛЬНЫХ ТРАСС НА РАЗЛИЧНОМ УДАЛЕНИИ ОТ ГОРОДА УЛЬЯНОВСКА

Studies to study the contamination of agricultural landscapes with heavy metals were carried out in Ulyanovsk region. The materials for the research were soils, plants and snow cover, sampling of which was carried out near highways in different directions and distances (5 km, 10 km and 15 km) from the city of Ulyanovsk. In the east direction from the city, a pattern of increasing the content of Zn, Cu, Pb, Cd, Ni in the soil (gross and mobile form), plants and snow cover was traced. In soil samples, Zn was the most mobile, the amount of which (mobile form) varied from 7.0 to 10.7 mg/kg, the content of mobile compounds Cu, Pb, Cd, Ni did not change significantly. In 5 km (east of Ulyanovsk), the maximum values for the content of heavy metals in plants were found for Zn – 27.8 mg/kg; Cu – 18.9 mg/kg; Pb – 0.62 mg/kg; Cd – 0.30 mg/kg, Ni – 0.87mg/kg of dry matter, there was no excess of MDU it was established in none of the observation sites. A direct dependence of the cadmium content in plants on its content in soils was noted, with an increase in the content in the soil (5.9 mg/kg), its content in plants increased to 0.30 mg/kg. The content of Zn, Cu, Ni at all snow collection points is significantly lower than the MPC. The excess of the MPC was recorded at almost all sampling points in terms of Pb and Cd content by 2.0...7.0 times.

Responses of individual and combined polystyrene and polymethyl methacrylate nanoplastics on hormonal content, fluorescence/photochemistry of chlorophylls and ROS scavenging capacity in Lemna minor under arsenic-induced oxidative stress

Nanoplastics alter the adverse impacts of hazardous contaminants such as heavy metals by changing their adsorption and accumulation. Few findings are available on the interaction between nanoplastic and heavy metals in plants. However, there is no report on the mechanisms for removing metal stress-mediated oxidative damage by the combination treatments of nanoplastics. To address this lack of information, polystyrene nanoplastic (PS, 100 mg L-1) and polymethyl methacrylate (PMMA, 100 mg L-1) were hydroponically applied to Lemna minor exposed to arsenate (As, 100 μM) for 7 days. PS or PMMA caused a reduction in the contents of N, P, K, Ca, Mg and Mn, but the improved contents were detected in the presence of PS or PMMA plus As stress. The hormone contents (auxin, gibberellic acid, cytokinin, salicylic acid and jasmonic acid) reduced by stress were re-arranged through PS or PMMA applications. Based on chlorophyll efficiency, fluorescence kinetics and performance of PSII, the impaired photosynthesis by As stress was improved via PS or PMMA applications. This alleviation did not continue under the combined form of PS and PMMA in As-applied plants. All analyzed antioxidant activity (superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX), glutathione reductase (GR), glutathione S-transferase (GST), glutathione peroxidase (GPX), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR)) decreased or unchanged under As, PS or PMMA. Due to the inactivation of the defense system, L. minor had high levels of hydrogen peroxide (H2O2) and thiobarbituric acid reactive substances (TBARS), showing lipid peroxidation. After As toxicity, induvial applications of PS or PMMA indicated the activated enzyme capacity (SOD, POX, GST and GPX) and upregulated AsA/DHA, GSH/GSSG and redox state of GSH, which facilitated the removal of radical accumulation. The efficiency of the antioxidant system in As + PS + PMMA-applied L. minor was not enough to remove damage induced by As stress; hereby, TBARS and H2O2 contents were similar to the As-treated group. Our findings from alone or combined application of PS and PMMA provide new information to advance the tolerance mechanism against As exposure in L. minor.

Heterologous expression of the tobacco metallothionein gene NtMT2F confers enhanced tolerance to Cd stress in Escherichia coli and Arabidopsis thaliana

Heavy metal pollution in the soil is a serious threat to crop growth and human health. Metallothionein (MT) is a low molecular weight protein that is rich in cysteine, which can effectively alleviate the toxicity of heavy metals in plants. In this study, a novel metallothionein encoding gene, NtMT2F, was cloned from the Cd-hyperaccumulator tobacco and heterologously expressed in E. coli and A. thaliana to verify its biological function. Recombinant E. coli incubated with NtMT2F effectively resisted heavy metal stress, particularly Cd. The recombinant strain grew significantly faster and had a higher content of Cd than the control. Mutations in the C-terminal Cys residues of NtMT2F significantly reduced its ability to chelate heavy metals. The overexpression of NtMT2F significantly enhanced resistance to Cd toxicity in transgenic A. thaliana. The germination rate, root length, and fresh weight of transgenic plants under Cd stress were higher than those of the wild type (WT). The contents of hydrogen peroxide (H2O2) and malondialdehyde (MDA) were lower than those of the WT. In addition, the activities of anti-peroxidase enzymes including glutathione reductase (GR), catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD), were significantly increased in the transgenic plants. The results of this study indicate that NtMT2F significantly improved the tolerance of microorganisms and plants to Cd and could be an important candidate protein for phytoremediation.

CaFe-layered double hydroxide corn straw biochar reduced heavy metal uptake by Brassica campestris L. and Ipomoea aquatic F.: Rhizosphere effects and oxidative stress alleviation

In the present study, CaFe-layered double hydroxide corn straw biochar (CaFe-LDH@CSB) was applied to the rhizosphere soil of both pakchoi (Brassica campestris L. ssp. Chinensis Makino, B. campestris L.) and water spinach (Ipomoea aquatic F., I. aquatic F.) to explore and clarify the potential mechanism by which CaFe-LDH@CSB helps vegetables reduce heavy metal (HM) uptake and alleviate oxidative stress. Pot experiments were conducted with CaFe-LDH@CSB applied at four levels: control (CK), T1 (5 g kg−1), T2 (10 g kg−1) and T3 (20 g kg−1). The results indicated that the application of CaFe-LDH@CSB significantly increased pH and decreased the acid-soluble forms of Cd, Pb, Zn and Cu in the rhizosphere soil of both B. campestris L. and I. aquatic F.; decreases of 39.4%, 18.0%, 10.0% and 33.3% in B. campestris L. and of 26.6%, 49.1%, 13.2% and 36.8% in I. aquatic F., respectively, were observed at the T3 level. Moreover, CaFe-LDH@CSB application reduced HM uptake by B. campestris L. and decreased HM-induced oxidative stress through the regulation of soil physicochemical properties and microbial abundance. For B. campestris L., variations in Sordariomycetes helped alleviate the accumulation of HMs in the aerial part, while GSH and –SH from the nonenzymatic system played an important role in scavenging H2O2 in leaves, thus helping B. campestris L. alleviate HM-induced oxidative stress. For I. aquatica F., variations in Vicinamibacteria and Mortierellomycetes helped alleviate the accumulation of HMs in plants, while GSH and PCs from nonenzymatic systems played an important role in removing ·O2− in leaves, thereby helping I. aquatica F. alleviate HM-induced oxidation stress. Our study indicated that the application of CaFe-LDH@CSB improved the rhizosphere soil environment and rebuilt the soil microbial community, helping B. campestris L. and I. aquatica F. alleviate HM-induced oxidative stress and promoting the growth of both vegetables.

BEHAVIOR OF HEAVY METALS IN SOIL-CONDENSATE-PLANTS SYSTEM IN THE ULAN-UDE LANDFILLS

The impact of waste dumps on environmental components, i.e., soil, evaporating soil water (condensate) and plants is studied. It has been revealed that industrial and municipal waste dumps continue to affect significantly the environment after their closure. The behavior of heavy metals (Pb, Cu, Zn, Ni, Cd, Co, Sb, Sn, Bi, Hg, and Cr) in soils, plants, and condensate in landfill areas and beyond them (the background) has been studied in detail. It has been found out that soils, plants and condensate at landfills are enriched in heavy metals as compared to the background sites. The degree of soil contamination at waste dumps depends on the reclamation stage of the latter. The landfill soils exceed the norms of maximum permissible concentrations for heavy metals by 1.1–90 times. Concentrations of heavy metals in plants exceed the background values from 1.1 to 104 times at all dumps. The maximum level of heavy metals in plants is exceeded for Zn, Cd, Cr. In the condensate sampled at the dumps, MPC is exceeded for Cu, Zn, and Hg. Based on the analysis results, the geochemical rows of heavy metal distribution in different landfill environments were compiled: in plants – Zn Cu Cr Ni Pb Cd Co Hg Sn Bi; in condensate – Zn Cu Ni Cr Pb Sn Co Hg Sb Cd Bi; in the soil – Zn Cr Cu Ni Pb Co Sb = Sn Cd. The distribution of heavy metals in the condensate and plants is similar. In these environments, contribution of Zn and Cu is more than 80%, contribution of Cr, Ni, Pb varies from 1 to 10%; contribution of Cd, Co, Sb, Sn, Bi, Hg is less than 1%. Heavy metals are distributed in soil according to a different pattern: the main contributors are Zn and Cr (their input is more than 50%), then go Ni, Cu, Co, and Pb (their content in soil varies from 1 to 50%), followed by Sb, Sn, and Cd (their content is less than 1%). Total pollution indices (Zc) of the soil, condensate and plants have been calculated for each landfill. Based on Zc, the landfills were grouped in a ranking series, which can form the basis for assigning the sequence of landfill reclamation measures.

Uranium triggers ferroptosis-like cell death in Vicia faba roots by increasing iron accumulation and inhibiting glutathione peroxidase activity

Uranium (U) is a non-essential and toxic element that can cause cell death in plants, but the mechanism is unclear. In the present study, we found that U triggered iron (Fe)- and reactive oxygen species (ROS)-dependent ferroptosis-like cell death in Vicia faba roots. The results showed that U entered V. faba root cells and even accumulated in the nucleus and organelles. U accumulation resulted in obvious changes in mitochondrial morphology, including shrunken shape, rupture of outer membrane, increased density of inner membrane and fuzzy crista. Compared with the control, the accumulation of Fe and ROS in V. faba roots increased after U exposure, while the peroxidase (POD) and glutathion peroxidase (GPX) activities decreased significantly, which was only 57.7% and 14.3% of control, respectively. Transcriptomic data showed that the expression of genes related to ROS production was mainly up-regulated (e.g. NDH , CCR , RbohB ), while the expression of genes related to ROS scavenging was mainly down-regulated (e.g. GPX4 , POD1 , POD7 ). These results led to excessive accumulation of ROS in root cells and triggered ferroptosis-like cell death. The key mechanism of U triggering ferroptosis-like cell death was to increase Fe accumulation and decrease GPX activity, so the cell death was promoted by addition of Fe (FeSO 4 and FeCl 3 ), and was inhibited by the lipophilic antioxidants [ferrostatin (Fer-1) and Vitamin E (VE)] and the Fe chelators [ciclopirox olamine (CPX)]. In conclusion, we demonstrated for the first time that U triggered ferroptosis-like cell death in V. faba roots. Our results provide a new insight for revealing the toxicological mechanism of U and other heavy metals in plants. • Uranium triggered ferroptosis-like cell death in Vicia faba roots. • Uranium accumulated in the nucleus and organelles after entering root cells. • Uranium induced iron accumulation and lipid peroxidation in Vicia faba roots. • Uranium severely inhibited GPX4 expression and glutathione peroxidase activity.

RESEARCH ON THE HEAVY METAL CONTENT IN ONION BULBS CORRELATED WITH SOIL FROM PRIVATE HOUSEHOLDS LOCATED IN THE COPŞA MICĂ AREA, CENTRAL ROMANIA

Food safety and the high demand for food have represented worrisome problems worldwide in recent decades. It is well known that plants can accumulate metals from contaminated soil and through deposits from pollutant emissions released by contaminated sources. Cadmium, copper, zinc, and lead are poisonous elements. The accumulation of heavy metals in plants grown in polluted areas represents a major risk to human and animal health. Soil pollution with heavy metals is a global problem that has an unfavourable impact on the environment. For this study, data collected from 65 individual households located in the Copşa Mică area were used to estimate the bioaccumulation of four different heavy metals [cadmium (Cd), lead (Pb), zinc (Zn), and copper (Cu)] in onion bulbs in different scenarios, in correlation with the total metal content from the soil. The highest correlation coefficients were obtained for the regression curves established for the estimation of Cd (r = 0.648***), Zn (r = 0.592***), and Pb (r = 0.525***) in onion bulbs. In the case of copper (Cu), the linear correlation coefficient was insignificant (r = 0.088ns). The mean cadmium and lead values determined in the onion samples from the study area did not exceed the maximum stable levels for these contaminants in vegetables.

Investigating the urban land pollution level according to the bioindicator properties of plants

In this article, the bioindicator properties of Taraxacum officinale, a common plant in urban areas, are studied. The existence of a correlation between the environment and the content of heavy metals in plants determines the use of plants as indicators of natural and anthropogenic landscapes. The existence of a relationship between the amount of heavy metals in the environment and plants determines their use as indicators of pollution of natural and anthropogenic landscapes. Plant organisms are recognized as adequate bioindicators of environmental quality. It is T. officinale that is suitable for identification and has adequate response to changes in environmental conditions. As a bioindicator, plants in urban and industrial areas are used for biomonitoring. In our scientific research, the use of T. officinale species as a bioindicator of atmospheric and soil pollution was investigated for the first time in the conditions of Uzbekistan. In order to determine the accumulation of some heavy metals in the observation areas, the correlation of climate, soil and plant indicators was determined using mathematical analysis methods.

Phytoremediation Potential of Arbuscular Mycorrhizal Fungi and Berseem in Soil Irrigated with Industrial Wastewater

This article describes a new idea about industrial pollution abatement through berseem ( Trifolium alexandrinum L.) using arbuscular mycorrhizal fungi (AMF) Glomus Spp. as an accelerating agent. For this purpose, berseem plant was grown on soil irrigated with industrial wastewater in pots. Three cuttings of plants were obtained at different intervals. At each cut, plant biomass, plant height, and rate of mycorrhizal infection were recorded and plant tissues (roots, stems and leaves) were analyzed to determine the concentrations of Cd, Cr, Pb, and Zn as indicators. The results showed that the biomass of the roots, stems, and leaves of the inoculated plants was higher than that of the un-inoculated plants. The height of inoculated plants was higher compared with that of uninoculated plants. The mycorrhizal infection rate was recorded highest at the third cut. Heavy metals in plants were within permissible limits for crops irrigated with wastewater) at each cutting. With inoculation, Zn and Cr concentrations in roots and leaves increased and Pb and Cd enhanced in roots but reduced in leaves as compared to un-inoculated plants, indicating that metals accumulated more in roots due to inoculation. The effectiveness can be confirmed by calculating the difference between the inoculated and non-inoculated plants. The new results showed that AMF inoculation promoted plant biomass and height, reduced metal transfer in leaves and stems, and to roots. This research confirmed that the procedure can be used for protecting plants from toxicity. Keywords: arbuscular mycorrhizal fungi, heavy metals, biomass, mycorrhizal infection rate, berseem. https://doi.org/10.55463/issn.1674-2974.50.4.6

Application of Visible/Near-Infrared Spectroscopy and Hyperspectral Imaging with Machine Learning for High-Throughput Plant Heavy Metal Stress Phenotyping: A Review

Heavy metal pollution is becoming a prominent stress on plants. Plants contaminated with heavy metals undergo changes in external morphology and internal structure, and heavy metals can accumulate through the food chain, threatening human health. Detecting heavy metal stress on plants quickly, accurately, and nondestructively helps to achieve precise management of plant growth status and accelerate the breeding of heavy metal-resistant plant varieties. Traditional chemical reagent-based detection methods are laborious, destructive, time-consuming, and costly. The internal and external structures of plants can be altered by heavy metal contamination, which can lead to changes in plants’ absorption and reflection of light. Visible/near-infrared (V/NIR) spectroscopy can obtain plant spectral information, and hyperspectral imaging (HSI) can obtain spectral and spatial information in simple, speedy, and nondestructive ways. These 2 technologies have been the most widely used high-throughput phenotyping technologies of plants. This review summarizes the application of V/NIR spectroscopy and HSI in plant heavy metal stress phenotype analysis as well as introduces the method of combining spectroscopy with machine learning approaches for high-throughput phenotyping of plant heavy metal stress, including unstressed and stressed identification, stress types identification, stress degrees identification, and heavy metal content estimation. The vegetation indexes, full-range spectra, and feature bands identified by different plant heavy metal stress phenotyping methods are reviewed. The advantages, limitations, challenges, and prospects of V/NIR spectroscopy and HSI for plant heavy metal stress phenotyping are discussed. Further studies are needed to promote the research and application of V/NIR spectroscopy and HSI for plant heavy metal stress phenotyping.

The concentration of heavy metals in the energy crops phytomass when grown in the conditions of Zhytomyr Polissia

The high level of anthropogenic pressure on agro-landscapes recently leads to an increased level of their contamination with heavy metals, which are among the most harmful chemical pollutants for the environment. Heavy metals are transmitted through trophic chains with a pronounced cumulative effect, in connection with which their toxicity can appear suddenly on individual links of trophic chains. The danger from heavy metals is determined by the fact that, unlike organic pollutants, they do not break down, but change from one form to another. Based on the results of the study, it was established that the accumulation of heavy metals by energy plants depended on the type of crop. Thus, it was proved that the concentration of heavy metals in energy crops plants when grown in the territory of radioactive contamination was within the limit of permissible concentrations. The lowest concentration of toxicants was noted when all energy crops were grown without fertilizers. The subject of the study was energy crops (Silhium perfoliatum L., Sorghum almum Parodi, Bunias orientalis L., Sida hermaphrodita Rusby, Miscanthus giganteus G.), heavy metals in plants, sod-podzolic sandy soil, mineral fertilizers. Therefore, the purpose of our research was to determine the phytomass of energy crops grown in areas contaminated with radionuclides as a result of the accident at the Chernobyl Nuclear Power Plant to determine the concentration of toxic substances. When performing the work, both general and special research methods were used: field – for conducting stationary and short-term field experiments, analytical – for determining the content of heavy metals in plants crops (Silhium perfoliatum L., Sorghum almum Parodi, Bunias orientalis L., Sida hermaphrodita Rusby, Miscanthus giganteus G.). The research was conducted during 2017−2020 on sod-podzolic soils in the territory of the village. Khrystynivka, Zhytomyr region, which belongs to the zone of unconditional (mandatory) resettlement (2nd zone of radioactive contamination). Prospects for further research will be aimed at establishing patterns of distribution of heavy metals in soil layers when growing energy crops. Key words: Silhium perfoliatum L., Sorghum almum Parodi, Bunias orientalis L., Sida hermaphrodita Rusby, Miscanthus giganteus G., lead, cadmium, copper, zinc.

Silicon-Rich Biochar Detoxify Multiple Heavy Metals in Wheat by Regulating Oxidative Stress and Subcellular Distribution of Heavy Metal

Silicon is a quasi-essential trace nutrient for plant growth and is frequently employed to remediate soils of heavy metal pollution in agriculture. However, silicon’s role and mechanism in reducing heavy metal toxicity have not been well understood, especially for multi-heavy metals such as cadmium, zinc, lead, and arsenic (usually treated as a heavy metal). In this study, the effects of different silicon-rich materials (silicate, rice husk biochar (RHB), and RHB + bentonite) on growth trait, antioxidant response, heavy metal accumulation, and distribution of wheat grown in two soils polluted by multiple heavy metals (Cd, Zn, Pb, and As) were investigated. The results revealed that the addition of silicon-rich materials enhanced plant growth, improved the photosynthetic attributes in leaf tissues, and decreased the contents of Cd, Zn, Pb, and As in wheat shoots and grains. The examination of the subcellular distribution of heavy metals in plants implied that silicon-rich materials transferred heavy metals as intracellular soluble fractions to the cell walls, indicating the reduction of mobility and toxicity of heavy metals in the plants. In addition, the application of the silicon-rich materials reduced oxidative damage in plants by downregulating plant antioxidant response systems and decreasing the production of malondialdehyde (MDA), ascorbic acid (AsA), and glutathione (GSH). Moreover, fractionation analysis of soil heavy metals showed that silicon-rich amendments could convert bioavailable heavy metals into immobilized forms. With the comparation of different silicon-rich materials, combined RHB and bentonite could better remediate multi-heavy metal-polluted soils and promote wheat production. The effect of the silicate component was stressed in this paper but some of the potential benefits might have arisen from other components of the biochar.

Physiological Response of Two Typical Plant Species under Combined Pb and Cd Stress in Bioretention Facilities

Bioretention facilities reduce stormwater runoff and pollutants, but there is a concern that plants in bioretention facilities may absorb heavy metal pollutants from stormwater runoff, which might impair the growth of the plant species. To investigate this issue, stormwater runoff containing various amounts of Pb and Cd heavy metals was used as the irrigation water in a bioretention facility. The low concentrations of Pb and Cd were 0.08 and 0.04 mg/L, and the high values were 0.68 and 0.32 mg/L. The plant heavy metal content and physiological indicators were measured. The indicators were chlorophyll content (CC), net photosynthetic rate (NPR), and transpiration rate (TR). The results showed that the changes in plant chlorophyll content (CC) were highly correlated with changes in the plants’ Pb. Low concentrations of Pb and Cd slightly inhibited the Ginkgo biloba L. and Ligustrum × vicaryi NPRs, the effect was more obvious at high concentrations and the Ligustrum × vicaryi’s NPR decreased from the initial 8.97 μmol CO2/(m2s) to 5.77 μmol CO2/(m2s) under high concentration conditions. Pb and Cd increased the Ginkgo biloba L. and Ligustrum × vicaryi’s TRs, and the effect at low Pb and Cd concentrations was more significant. Under low concentrations of Pb and Cd stress, the Ginkgo biloba L.’s TRs reached 0.63 mmol H2O/(m2s), Ligustrum × vicaryi’s TRs reached 1.30 mmol H2O/(m2s). The TRs of the two plants in the experimental groups remained high throughout the experiment, and there was no significant inhibition. The study found that Pb and Cd in stormwater runoff did affect the physiological function of species to some extent. Different plant species behaved differently in bioretention facilities, but the stormwater runoff did not lead to the death of species. Our study may provide a better understanding of the development of typical plant species in bioretention facilities.

Phytoremediation plants of metals in leached urban solid waste Phytoremediation in landfill

Leachate is among the main pollutants in landfills, specifically because its components can cause danger to the environment. One of the treatment options is phytoremediation, which is an efficient technique with low environmental impact and reduced costs. The potential for phytoremediation of heavy metals in plants exposed to Urban Solid Waste leachate from a final disposal site located in Tabasco, Mexico was evaluated. Five plant species predominant in the landfill coverage were selected and identified: Pennisetum purpureum, Cyperus esculentus, Canna indica, Dactylotenium scindicun and Echinochloa colona. Subsequently, leachate samples were collected from each plant and adjacent soil for determination of Heavy Metals through ICP-OES (n=3). The metals with the highest concentration in the leachate were Ba and Zn. Independently of the species, Barium was absorbed at a higher concentration. The higher Bioconcentration Factor was observed in Thallium by D. scindicum and C. indica, and the Translocation Factor identified hyperaccumulating species: E. colona (Zing and Barium) C. indica (Zing and Barium), P. purpureum (Thallium) and D. scindicum (Barium and Thallium).

Different effects and mechanisms of polystyrene micro- and nano-plastics on the uptake of heavy metals (Cu, Zn, Pb and Cd) by lettuce (Lactuca sativa L.)

Heavy metals are widely distributed in soil ecosystems, posing a potential threat to soil biota. Micro- and nano-plastics (MNPs) can impact the accumulation of heavy metals in plants through changing soil microbial community and cause injury to plants. In this work, two concentrations (100 and 1000 mg/kg) polystyrene microplastics (PS-MPs) and nanoplastics (PS-NPs) were adopted to explore the effects and mechanisms of MNPs on the uptake of Cu, Zn, Pb and Cd in lettuce (Lactuca sativa L.). MPs increased the uptake of heavy metals in lettuce by increasing the relative abundance of the key metal-activation bacteria in rhizospheric soil. At the end of experiment, the contents of Cu, Zn, Pb and Cd in NP treatments were significantly (p < 0.05) higher than that of MPs, particularly in 1000 mg/kg of NPs, with concentrations of 52.6, 174, 10.3, and 33.2 mg/kg, respectively. Biomarkers and gene expression reveled that 1000 mg/kg of NPs caused more severe injuries to lettuce plant at the end. Moreover, metabolomic analysis demonstrated that NPs disturbed the metabolism of ATP-binding cassette transporter (ABC transporter) and plant hormone signal transduction of lettuce root, causing increased uptake of heavy metals by lettuce. This work reveals that MPs may increase accumulation of heavy metals by altering the rhizosphere microorganisms, whereas NPs increase accumulation of heavy metals by causing more severe injuries to lettuce plant.

Amino acid composition of proteins of meristem cells of maize roots under the combined action of lead, cadmium and nickel ions

Heavy metals are one of the main causes of plant damage. The main route of entry of metals into plants is their absorption by the root system from the soil. The accumulation of heavy metals in plants disrupts the flow of biochemical processes. Amino acid metabolism is one of the important factors that ensure biochemical adaptation of organisms to environmental changes. Therefore, the aim of the work was to study the content of protein amino acids in the generative tissues of the maize root under the combined action of lead, cadmium and nickel ions at the early stages of ontogenesis. To assess the impact of heavy metals, two-day-old corn seedlings were transplanted to solutions with heavy metal ions of various concentrations, both individually and in a mixture. The content of protein amino acids in the meristem was characterized by significant variation associated with both quantitative and qualitative changes in the composition of water-soluble proteins during germination. The level of accumulation of amino acids in the meristem cells of maize roots depended on the concentration of the xenobiotic and the germination period, and the general regularity of the influence of nickel ions was a decrease in the content of arginine, leucine, alanine and an increase in the content of histidine, cysteine, serine, proline, and valine. During the period of germination, the qualitative amino acid composition of plants did not change, while the quantitative content of individual amino acids varied greatly. Various increases in the content of dicarboxylic amino acids (glutamate and aspartate) testify to the intensification of metabolic processes under the influence of the studied substances. However, it cannot be excluded that the increase in the content of glutamic and aspartic acids is associated with a decrease in the speed of their utilization. In addition, heavy metals caused an increase in the content of amino acids of the ornithine cycle (arginine) and the end product of the cycle (proline) to varying degrees. Proline is an amino acid that has a stress-protective effect due to the binding of proline aggregates to surface hydrophobic residues of proteins, which prevents their denaturation. Perhaps a similar protective effect of proline occurs in the case, which is being considered.