Absorption Of Pb Research Articles

Enhancing lead removal from wastewater and alleviating lead stress in soil-wheat systems using starch-stabilized Fe-Ni/biochar composites: Synthesis and physico-chemical investigations

In this study, starch-stabilized and Fe/Ni bimetal modified biochar composites of StFeNi-BC and StFeNi-BC-350 were successfully fabricated and applied in removing Pb(II) from aqueous solutions. The absorption of Pb(II) by StFeNi-BC and StFeNi-BC-350 were controlled by monolayer chemisorption and their maximum adsorption capacities were 122.767 and 148.043 mg/g, respectively. Mechanism studies showed that electrostatic attraction, ion exchange, complexation and physical adsorption occurred on the adsorbent surface. Studies on the influence of co-existing metal ions and water matrices on adsorption of Pb(II) demonstrated that StFeNi-BC-350 displayed high anti-interfering ability and promising application prospect for Pb(II) removal. In addition, StFeNi-BC-350 was applied in soil-wheat pot systems to further investigate its influence on reducing Pb induced oxidative stress on wheat. Compared with the control, the addition of StFeNi-BC-350 increased the biomass and total chlorophyll content in leaves, and decreased the activity of antioxidant enzymes (MDA, SOD, CAT, POD) together with ROS fluorescence intensity of wheat. The results indicated that StFeNi-BC-350 could alleviate Pb(II) stress of wheat. Furthermore, the addition of StFeNi-BC-350 improved the physicochemical properties of the soil, and increased the abundance as well as the number of soil microorganisms, thereby alleviating Pb stress on wheat. Therefore, StFeNi-BC-350 is suitable for the practical treatment of Pb-contaminated water and soil.

Risk-spreading strategies of two dwarf bamboos in heterogeneous Pb (lead) environments

As a typical clonal plant, dwarf bamboo has potential applications in the remediation of Pb (lead) -contaminated soils; however, the environmental risk-spreading strategies of dwarf bamboo in heterogeneous Pb-contaminated environments are not known. To this end, we conducted hydroponic experiments on two species of groundcover bamboo, Sasa fortunei (Van Houtte) Fiori (SF) and Sasa auricoma (Mitford) E.G. Camus (SU), with seven treatments including two environments, homogeneous and heterogeneous. The results showed that SF protected the distal ramets (DRs) and that SU did the opposite in a homogeneous Pb environment. In the heterogeneous Pb environment, the NTR of both bamboos (RSISF = 0.64/0.44, RSISU = 0.40/0.33) was higher than that under the heterogeneous high-concentration environment (RSISF = 0.15/0.28, RSISU = 0.26/0.26). Moreover, the total Pb concentration of SF was as high as 80123.5 mg/kg and that of SU was as high as 53333.33 mg/kg, and in general, SF was more capable of absorbing Pb. In the heterogeneous low-Pb environment, the ascorbic acid and proline levels of the TRs (Pb-treated ramets) were elevated to alleviate oxidative stress; in contrast, antioxidant enzyme activities of SU were all reduced due to the damage caused by Pb absorption. The results of the experiments showed that SF had a greater risk-spreading capacity and higher Pb concentrations than SU in heterogeneous environments, and therefore, SF had better Pb bioenrichment and tolerance than SU. We proposed a novel metric (RSI) to assess the ability of plants to spread risk, and the results of the study provid a basis for dwarf bamboo phytoremediation in heterogeneous Pb environments.

Exogenous chelating agents influence growth, physiological characteristics and cell ultrastructure of Robinia pseudoacacia seedlings under lead-cadmium stress.

Heavy metal pollution of soil, especially by lead (Pb) and cadmium (Cd), is a serious problem worldwide. The application of safe chelating agents, combined with the growing of tolerant trees, constitutes an approach for phytoremediation of heavy-metal-contaminated soil. This study aimed to determine whether the two safe chelators, tetrasodium glutamate diacetate (GLDA) and citric acid (CA), could improve the phytoremediation capacity of black locust (Robinia pseudoacacia L.) in a Pb-Cd-contaminated soil and to find the key factors affecting the biomass accumulation of stressed black locust. In Pb- and Cd-stressed black locust plants, medium- and high-concentration GLDA treatment inhibited the growth, chlorophyll synthesis and maximum photochemical efficiency (Fv/Fm), promoted the absorption of Pb and Cd ions and resulted in the shrinkage of chloroplasts and starch grains when compared with those in Pb- and Cd-stressed plants that were not treated with GLDA. The effects of CA on plant growth, ion absorption, chlorophyll content, chlorophyll fluorescence and organelle size were significantly weaker than those of GLDA. The effect of both agents on Cd absorption was greater than that on Pb absorption in all treatments. The levels of chlorophyll a and plant tissue Cd and rates of starch metabolism were identified as the key factors affecting plant biomass accumulation in GLDA and CA treatments. In the future, GLDA can be combined with functional bacteria and/or growth promoters to promote the growth of Pb- and Cd-stressed plants and to further improve the soil restoration efficiency following pollution by heavy metals. Application of CA combined with the growing of black locust plants has great potential for restoring the Cd-polluted soil. These findings also provide insights into the practical use of GLDA and CA in phytoremediation by R. pseudoacacia and the tolerant mechanisms of R. pseudoacacia to Pb-Cd-contaminated soil.

Effects of Different Control Measures on Cadmium and Lead Accumulation and Quality in Lettuce

To explore the safe utilization technology of farmland polluted by the heavy metals cadmium (Cd) and lead (Pb) and to realize the safe production of agricultural products, a pot experiment was conducted to investigate the effects of two soil passivators and five foliar inhibitors on Cd and Cd-accumulation and quality of lettuce with low Pb and Cd accumulation (KCW). The results showed that different control measures had different effects on the soil pH value of lettuce, and the application of 45 g·m-2biochar-based passivator had the most significant difference in improving the soil pH value, which was increased by 0.8 units compared with that in CK. By using 72 g·m-2 of humic acid passivator yielded notable difference in reducing the soil pH value of lettuce. A reduction of 0.25 units was achieved compared with that in CK. Among all the control measures, the application of 45 g·m-2 biocharcoal-based passivation agent had the best effect on reducing soil available Cd content, which was significantly reduced by 53% compared with that in CK, and the application of 135 g·m-2biocharcoal-based passivation agent had the best effect on reducing soil available Pb content, which was significantly reduced by 64% compared with that in CK. Spraying 0.8% FAK-Zn foliar inhibitor not only had the best control effect on reducing Cd and Pb contents in the edible parts of lettuce, which were significantly reduced by 77% and 60%, respectively, compared with that in CK, but it also significantly reduced Cd and Pb enrichment coefficients and transport coefficients from the root to the edible parts of the lettuce. Different control measures had different effects on the nutritional quality of lettuce, and 0.4% FAK-Zn foliar inhibitor had the best effect on soluble protein. The 0.6% FAK-Zn had the best effect on soluble sugar, and the 0.4% FAK-Zn inhibitor had the best effect on vitamin C content. The application of biocarbon-based passivator could effectively repair lettuce soil polluted by Cd and Pb, whereas the application of FAK-Zn leaf surface inhibitor could effectively inhibit the accumulation, absorption, and transfer of Cd and Pb in lettuce; improve the nutritional quality of lettuce; provide a theoretical basis for safe production of vegetables polluted by heavy metals; and promote the recycling of resources and environment.

Probing the effects of silicon amendment on combined stressors on rice: Lead pollution and blast fungus (Magnaporthe oryzae) infection

As agroecology deteriorates, agricultural production is threatened by the combined stressors of exposure to environmental pollutants and pathogenic microbes. Proper agronomic practices for crop growth management and fertilization require understanding plant tolerance strategies. Both rice blast and heavy metals substantially impair rice crops, while silicon (Si) is an effective amendment to alleviate the combined stressors. Herein, this study was conducted to investigate the rice physiology and pathology perspective on the mechanism of Si alleviation against both lead (Pb) toxicity and Magnaporthe oryzae infection, utilizing pot experiments with inoculation of the virulent Magnaporthe oryzae strain. Exogenous Si reduced the phyto-availability and plant absorption of Pb, resulting in a 73.5% reduction in exchangeable Pb concentration in soil and a 40.23% reduction in rice plants. Furthermore, Si addition boosted the plant antioxidant system by increasing the activities of related enzymes, as the activities of catalase, superoxide dismutase, and polyphenol oxidase were significantly improved while the activity of peroxidase in rice panicles decreased. As a result, an improvement in dry matter quantity by 19.19% was observed compared to treatments without Si application, and the panicle blast severity (PBS) was reduced by 0.4–37.52%. Notwithstanding the interaction between the combined stressors, this study revealed that the speciation of Pb formation in the rhizosphere was the primary contributor to the alleviation of abiotic stresses, whereas the regulation of oxidative stress by enzymatic antioxidants played a dominant role in alleviating Magnaporthe oryzae colonization and impairments. The regulation process may reveal the mechanism of siliceous fertilizer functioning in the paddy system. Thereby the role of exogenous Si in anti-fungal, heavy metal toxicology, and plant physiology needs further study to fully elucidate the role of Si amendment, which is proposed to be considered from the perspective of soil chemistry and plant physiology.

Chinese sapindaceous tree species (Sapindus mukorosii) exhibits lead tolerance and long-term phytoremediation potential for moderately contaminated soils

Heavy metal pollution in metropolitan soils poses significant risks to human health and the entire ecosystem. Effective mitigation strategies and technologies are crucial for addressing these environmental issues. Fast-growing trees are an essential part of phytoremediation projects all over the world and provide long-term ecological benefits to mankind. This study assessed the lead tolerance and phytoremediation potential of a fast-growing soapberry tree species (Sapindus mukorossi) in moderately contaminated soil. Two independent experiments were conducted to assess its tolerance at (i) germination level and (ii) prolonged growth stage. In the germination experiments, seeds were exposed to lead (II) nitrate Pb (NO₃)₂ at various concentrations (0, 5, 10, 20, 50, 100, 200, 300, 400 and 500 μM) for 120 days. Results showed significant differences in germination time, germination index, seedling vigor index, energy of germination, final germination, germination inhibition, seedling height and root/shoot weight compared to the control experiments. In the prolonged growth experiments, seedlings were grown for six months in soils amended/spiked with different Pb concentrations (T0 = 0, T1 = 20, T2 = 50, T3 = 100, T4 = 150 and T5 = 200 mg kg−1 soil) and their biomass was determined. The highest biomass achieved in six months (T0: 12.62 g plant−1), followed by (T1: 12.33 g plant−1), (T2: 12.42 g plant−1), (T3: 11.86 g plant−1), (T4: 10.86 g plant−1) and (T5: 10.06 g plant−1) respectively. S. mukorossi showed no visible signs of Pb toxicity over a six-month period. During six months of exposure, the total Pb content in S. mucrossi tissues were classified as roots > leaves > stems. The highest cumulative absorption of Pb occurred between the fourth and fifth months of exposure. Maximum transfer factor (TF) was detected during the fourth month ranging from 0.888 to 1.012 for the different Pb concentrations. Furthermore, the growth behavior, lead accumulation, bioconcentration factors (BCF) and tolerance index (TI) indicated that S. mucrossi may tolerate moderate Pb concentrations for longer periods. These findings suggest that S. mukorossi may be deployed for long-term phytoremediation coupled with urban forest applications in the future.

Sepiolite, Palygorskite, and Triple Super Phosphate on the Uptake of Heavy Metals by Two Iranian Wheat Cultivars Inoculated With Piriformospora indica Fungus

Background and Purpose: Soil remediation in contaminated soils is an important factor of environmental research. This research evaluated the effect of sepiolite, palygorskite, and triple super phosphate (TSP) on decreasing the heavy metals uptake by wheat cultivars inoculated with Piriformospora indica (P. indica). Materials and Methods: Treatments included applying sepiolite, palygorskite (at the rate of 0% and 5% (W/W), and TSP (0% and 0.5% W/W) in the Pb- and Zn-polluted soil under cultivation of 2 wheat cultivars (Mihan and Pishgam cultivars) that inoculated with P. indica fungus. Plants were harvested after 90 days, and Pb and Zn concentrations in soils and plants were measured using atomic absorption spectroscopy. Furthermore, the catalase (CAT) enzyme activity was also measured. Results: With applying 5% (W/W) sepiolite and palygorskite, the plant Pb concentration was significantly reduced by 11.8%, while the plant Zn concentration increased by 13.9%. Plant Zn and Pb concentrations considerably increased and decreased following plant inoculation. However, plant cultivars showed different results. Our results showed that the Pb and Zn concentrations were lower in Mihan than in the Pishgam wheat cultivar. In addition, increasing soil Pb availability caused a significant increase in CAT enzyme activity. Soil contamination with heavy metals had a negative impact on plant root colonization. Conclusion: The interaction of plant cultivars and P. indica significantly affected plant heavy metal uptake by plants. However, environmental studies have found that applying organic amendments like nan-clays or TSP can reduce the absorption of Pb by plants.

Effect of Sulfur Granular Municipal Solid Waste, Humic Acid, and Nano Fe-Oxide on Lead Uptake by Plants in a Calcareous Soil in the Presence of Thiobacillus

Soil poisoning with heavy metals is one of the most significant aspects of environmental research. In the soil treated with Thiobacillus, the effect of sulfur granular municipal solid waste (sulfur granular MSW), humic acid, and nano Fe-oxide on reducing Pb absorption by plants was investigated. Treatments consisted of applying sulfur granular MSW (0 and 30 t/ha), spraying humic acid (0 and 1.5 mmol/L), and using nano Fe-oxide (0 and 2% w/w) in the soil contaminated with Pb (0, 600, and 1200 mg/kg-soil). Plants were collected after 5 months, and the Pb content in the soil and plants was estimated by atomic absorption spectroscopy (AAS). The activity of ascorbate peroxidase (APX) and peroxidases (POX) enzymes were also determined. The use of 30 t/ha of sulfur granular MSW in the Pb-polluted soil reduced Pb concentration in the soil and plant by 13.4% and 15.1 %, respectively, while it increased Fe concentration by 15.2% in the plant. Using nano Fe-oxide (2% w/w) in the Pb-contaminated soil (600 and 1200 mg/kg soil) considerably enhanced Fe content in the plant. Pb absorption by plants was dramatically reduced by foliar application of humic acid. According to the findings of this study, the interaction effects of sulfur granular MSW, nano Fe-oxide, and humic acid significantly reduced the Pb absorption by plants. However, the impacts of soil physico-chemical characteristics and the kind of soil pollutant on plant Pb concentration cannot be ignored.

Co-transport behavior and Trojan-horse effect of colloidal microplastics with different functional groups and heavy metals in porous media

The emerging global problems of microplastics pollution and their co-occurrence with other pollutants have presented major new challenges for environmental health and protection. This study used column experiments to investigate the co-transport behavior and Trojan-horse effect of colloidal microplastics (non-functional polystyrene microspheres (MS), carboxyl-modified polystyrene microspheres (CMS) and sulfonate-modified polystyrene microspheres (SMS)) and lead (Pb) in porous media. Results showed that a Trojan-horse effect occurred during the co-transport of colloidal microplastics and Pb. In the process of co-transport, colloidal microplastics and Pb mutually inhibited each other’s transport at an ionic strength of 1 mM, which may be due to Pb absorption by microplastics, resulting in the destabilization of agglomerates and a reduction in the electronegativity of microplastics. At an ionic strength of 100 mM, colloidal microplastics and Pb promoted each other’s transport, potentially due to their competition for adsorption in porous media. The functional groups present on colloidal microplastics inhibited the transport of Pb at low ionic strengths, while at high ionic strengths Pb transport was promoted. Furthermore, deposition experiments verified that quartz crystal microbalance with dissipation (QCM-D) monitoring could effectively account for and predict the transport and deposition behavior of microplastics in the presence or absence of Pb.

Effects of Different Trace Elements on Ecophysiological Characteristics of Ligustrum obtusifolium Saplings

Phytoremediation is becoming more prevalent globally. Literature on phytoremediation strategies in western China is relatively scarce. The present research sought to fill this gap by examining the effects of trace elements such as Cd, Cr, Pb, and Zn on growth, physiological traits, tolerances, and accumulation characteristics in 2-year-old saplings of Ligustrum obtusifolium. The gradient of trace element concentration was determined by adding exogenous trace elements to the soil in a pot experiment: CK (no exogenous trace element), T1, T2, and T3 (Cd 0, 2, 5, and 10 mg/kg; Cr 0, 300, 500, and 700 mg/kg; Pb 0, 400, 800, and 1200 mg/kg; and Zn 0, 300, 500, and 1000 mg/kg, respectively). The results indicated that Chla, Chlb, and total Chls significantly decreased (p < 0.05) in the leaves of L. obtusifolium, with the lowest value obtained during soil treatment with T3. Along with the increase in trace element concentration, the net increase in height, root biomass, aerial biomass, and total biomass was reduced significantly. The net growth of L. obtusifolium under Cr stress did not differ significantly from that of CK at T1; however, the net growth of L. obtusifolium under Cr stress was considerably reduced at T2 and T3. The antioxidant enzyme activity of L. obtusifolium increased under different trace element stresses and first increased and then decreased as trace element levels increased. It was found that the SOD, POD, CAT, and APX activity of L. obtusifolium peaks at T2 under Cd and Zn stress in contrast to a peak at T1 under Cr and Pb stress. The contents of trace elements in L. obtusifolium roots, stems, and leaves increased along with the increase in soil trace element levels. Cr, Pb, and Zn threshold values can be set at 300 mg/kg, 400 mg/kg, and 300 mg/kg, respectively. This is carried out by using a reference index of the biomass of L. obtusifolium decreased by 10%, while the Cd threshold value needs to be further studied. L. obtusifolium would be an appropriate plant for phytoremediation of Cr-polluted soil, compared to Cd, Pb, and Zn absorption and accumulation. It showed optimal antioxidant enzyme activity and transfer ability under soil Cr contents of 300 mg/kg, and the growth of L. obtusifolium was not restricted. Therefore, L. obtusifolium was particularly suitable for phytoremediation of Cr pollution in areas in western China.

Novel electrochemical method to activate biochar derived from spent coffee grounds for enhanced adsorption of lead (Pb)

Biochar (BC) has received much attention as a promising adsorbent that can be exploited to remove heavy metals in domestic and wastewater. The adsorption capacity of BC is, however, relatively low compared to that of conventional adsorbents, and its performance is inversely proportional to its stability. Various chemical and physical methods have been tried to address these limitations, but BC activation still generates too much acidic or alkaline wastewater. Here we propose a novel electrochemical method and compare its lead (Pb) adsorption capacity to that of acid- and alkaline-based approaches. We found that electrochemical activation significantly increased the number of hydroxyl and carboxylic groups on the BC surface, which led to an increase in Pb absorption from 27 % (pristine BC) to 100 % because the oxygenated-functional groups contributed to the adsorption of Pb. Pb capacity was 1.36, 2.64, 3.31, and 5.00 mg g−1, corresponding to pristine, acidic, alkaline, and electrochemical activation, respectively. The Pb absorption capacity of electrochemically activated BC was also higher than that of acid- and alkali-activated BC, which we attribute to the observed increases in oxygen ratio and surface area. Moreover, the adsorption rate of BC after electrochemical activation was 190 times faster and its capacity was 2.4 times higher than that of pristine BC. These findings show that the electrochemical activation of BC results in greater adsorption capacity than conventional methods.

Direction of changes in porous structure and adsorption capacity during topochemical oxidation of coal activated by alkali

The purpose of the work is to evaluate the influence of topochemical oxidation (H2O2, HNO3) of carbon prepared by alkali activation of coal on porosity and ability to adsorb 4-chlorophenol (CPh), Pb(II) cations and iodine. Carbons were oxidized at the reactant/carbon ratio of 1:1 (mol/mol, 250С, 24 h). Based on nitrogen adsorption-desorption isotherms, the volumes and specific surfaces of ultramicro- (Sumi), supermicro- (Ssmi) and other pores were evaluated. Kinetics and adsorption isotherms (250С) of CPh and Pb(II) were characterized; adsorption capacities of CPh, Pb(II) and I2 were determined. The H2O2-assisted modification was found to significantly increase Sumi (from 615 to 829 m2/g), but decrease Ssmi (from 515 to 494 m2/g). The HNO3-assisted modification slightly increases Sumi (from 615 to 651 m2/g), does not change Ssmi, but forms mesopores. The CPh adsorption is best approximated by the second-order kinetics, and isotherms are well fitted with the use of the Langmuir model. The H2O2 treatment increases the CPh capacity from 314 to 389 mg/g; and the НNO3 modification significantly decreases the CPh capacity (to 189 mg/g). Modifications reduce the iodine capacity by 1.11 times (H2O2) and 2.33 times (HNO3). The Pb(II) absorption was established to describe by the second-order kinetics equation; the adsorption isotherms obey Langmuir (R20.986) and Freundlich (R20.984) models. The Pb(II) capacity slightly increases after H2O2-assisted modification (from 87 to 95 mg/g), but increases sharply (from 87 to 298 mg/g) after HNO3-assisted treatment because of significant increasing OH-acidic groups concentration.

Phytoremediation Ability of Ornamental Plants Celosia argantea L. and Mirabilis jalappa L. in Plumbum (Pb) Contaminated Soil

Plumbum or lead is a type of heavy metal that is dangerous if it has exceeded the threshold of 0.07 µg/g based on the National Standardization Agency SNI 2004. This type of heavy metal is found in nature such as in soil, water, and air. The purpose of the study was to determine the phytoremediation ability of two types of ornamental plants, namely Celosia argentea L. and Mirabilis jalappa L., against Plumbum (Pb) metal in soil. The growth parameters observed consisted of plant height, plant stem diameter, number of leaves, leaf length, and leaf width. The ICP-MS (Inductively coupled plasma-mass spectrometry) was used to analyze the plumbum (Pb) content in soil and plants. The results ofinitial soil analysis prior to the plant planting process (phytoremediation) were 103.17 µg/g which had exceeded the predetermined threshold. The result of the analysis after phytoremediation of Celosia argentea L. showed plumbum (Pb) content of 49.685 µg/g in soil and 1,9548 µg/g in plants. Similarly, the analysis of Ph content after phytoremediation of Mirabilis jalappa L. was 47.802 µg/g in soil and 5.3077 µg/g in plants. Based on biomass calculation of Celosia argentea L. and Mirabilis jalappa L., the obtained Plumbum (Pb) content was 18.84% and 27.85%, respectively. The percentage of Pb removal of Celosia argentea L. was 51.842%, while Mirabilis jalappa L. was 53.667%. The efficiency of Pb absorption of Celosia argentea L. and Mirabilis jalappa L. was 1.895% and 5.145%, respectively. In conclusion, Ornamental plants Celosia argentea L., and Mirabilis jalappa L., are able to act as phytoremediation agents for Plumbum (Pb) metal that pollutes the soil as evidenced by the decrease in Pb levels in the soil after the phytoremediation process.Keywords: Plumbum (Pb), Phytoremediation, Celosia argentea L., Mirabilis jalappa L.

Influence mechanism of awns on wheat grain Pb absorption: Awns' significant contribution to grain Pb was mainly originated from their direct absorption of atmospheric Pb at the late grain-filling stage

The spike is the organ that contributes the most to lead (Pb) accumulation in wheat grains. However, as an important photosynthetic and transpiration tissue in spike, the role of awn in wheat grain Pb absorption remains unknown. A field experiment was conducted to investigate the influence mechanism of awn on grain Pb accumulation through two comparative treatments: with and without awns (de-awned treatment). The de-awned treatment decreased wheat yield by 4.1 %; however, it significantly lowered the grain Pb accumulation rate at the late filling stage (15 days after anthesis) and led to a 22.8 % decrease in grain Pb concentration from 0.57 to 0.44 mg·kg-1. Moreover, the relative contribution of awn-to-grain Pb accumulation gradually increased with the filling process, finally reaching 26.6 % at maturity. In addition, Pb isotope source analysis indicated that the Pb in the awn and grain mainly originated from atmospheric deposition, and the de-awned treatment decreased the proportion of grain Pb from atmospheric deposition by 8.9 %. Microstructural observations further confirmed that the contribution of awns to grain Pb accumulation mainly originated from their direct absorption of atmospheric Pb. In conclusion, awns play an important role in wheat grain Pb absorption at the late grain-filling stage; planting awnless or short-awn wheat varieties may be the simplest and effective environmental management measure to reduce the health risks of Pb in wheat in regions with serious atmospheric Pb contamination.

Combination of Superabsorbent Polymer And Vetiver Grass As A Remedy For Lead-Polluted Soil

Heavy metal pollution in the soil environment is a worldwide environmental problem as it has negative effects on both human health and the environment. Remediation of heavy metal-contaminated soil is essential to improve soil quality, provide land resources for agricultural production, and protect human and animal health and the ecological environment. There is the possibility of remediating these contaminated soils through the use of several heavy metal absorbing plants and Superabsorbent polymers. Superabsorbent polymers (SAPs) are 3D polymer networks having hydrophilic nature, which can swell, absorb and hold a large amount of water or aqueous solutions in their network. This study evaluates the effect of superabsorbent polymer on Pb absorption capacity of Vetiver (Vetiveria zizanioides.L) that was grown on contaminated soil in Trai Cau iron ore dumpsite, Dong Hy district, Thai Nguyen province. The experiment was designed with five recipes and three replicates. The contents of SAP studied were 0, 0.6, 0.8, and 1.0 g/kg of soil. Uncontaminated soil was used as the control treatment. In the supplemented recipe of SAP, Vetiver showed better Pb treatment efficiency than the recipes without adding polymers. After 120 days of planting, SAP increased the tolerance and Pb absorption of Vetiver, improving soil properties. The best Pb treatment efficiency is achieved when using SAP with content from 0.8-1.0 g/kg soil.

Effects of mowing on Pb accumulation and transport in Cynodon dactylon (L.) Pers

Bermudagrass is a perennial herb with the potential to remediate Pb pollution in soils, and it has mechanical resistance to shearing. However, the effects of mowing on Pb absorption and accumulation in bermudagrass are still unclear. In this study, we investigated the effects of different quantities (0, 1, 2, 4 applications) of mowing treatments under 200mg L-1 Pb application on Pb accumulation and transport in bermudagrass and explored the related mechanisms. Compared to the Pb treatment, all of the mowing treatments greatly decreased root Pb concentration/accumulation, significantly enhanced Pb concentrations/accumulations in stubble stems and stubble leaves, and ultimately promoted Pb enrichment and transport. Of the treatments in this study, two applications of mowing best promoted Pb enrichment, and four applications of mowing best promoted Pb transport efficiency. Furthermore, mowing mediated the microdistribution and physiological patterns of Pb in bermudagrass and affected the Pb transport by changing the subcellar distribution patterns and chemical forms of Pb in various tissues. Additionally, mowing promoted the transport of all mineral elements and showed a synergistic relationship with Pb absorption and transport. The change in mineral element metabolism patterns may be an important reason why mowing promoted Pb accumulation in bermudagrass. Our study provides the first comprehensive evidence regarding mowing facilitating the absorption, accumulation and transport of Pb in bermudagrass. Moderate mowing may be an effective strategy to assist in soil Pb remediation using bermudagrass.

Study on the effect of lead (Pb) content in soil on the growth and lead (Pb) absorption of Vetiver grass (Vetiveria zizanioides L.)

Treatment of heavy metal pollution in soil by a biological method is currently being studied and widely applied in Vietnam. This study concentrated on the impact of lead (Pb) on the growth of Vetiver grass (Vetiveria zizanioides L.), and its capacity for lead absorption with the aim of removing them from the soil areas used for orange cultivation. Results conducted from the study showed that Vetiver grass could be grown in Pb-contaminated soil. With Pb content in soil of about 2500 mg/kg, Vetiver grass of 3 months old (from planting time) was recorded to accumulate the highest quantity of lead in its leaves and roots (42.91±1.27 and 865.92±17.67 mg/kg, respectively), resulting in the best ability in term of Pb contaminated removal from the soil (14.23±1.23mg). As a result, the relatively high lead accumulation of Vetiver grass mainly root system, was also reported.

Exopolysaccharide-producing bacteria enhanced Pb immobilization and influenced the microbiome composition in rhizosphere soil of pakchoi (Brassica chinensis L.).

Lead (Pb) contamination of planting soils is increasingly serious, leading to harmful effects on soil microflora and food safety. Exopolysaccharides (EPSs) are carbohydrate polymers produced and secreted by microorganisms, which are efficient biosorbent materials and has been widely used in wastewater treatment to remove heavy metals. However, the effects and underlying mechanism of EPS-producing marine bacteria on soil metal immobilization, plant growth and health remain unclear. The potential of Pseudoalteromonas agarivorans Hao 2018, a high EPS-producing marine bacterium, to produce EPS in soil filtrate, immobilize Pb, and inhibit its uptake by pakchoi (Brassica chinensis L.) was studied in this work. The effects of strain Hao 2018 on the biomass, quality, and rhizospheric soil bacterial community of pakchoi in Pb-contaminated soil were further investigated. The results showed that Hao 2018 reduced the Pb concentration in soil filtrate (16%-75%), and its EPS production increased in the presence of Pb2+. When compared to the control, Hao 2018 remarkably enhanced pakchoi biomass (10.3%-14.3%), decreased Pb content in edible tissues (14.5%-39.2%) and roots (41.3%-41.9%), and reduced the available Pb content (34.8%-38.1%) in the Pb-contaminated soil. Inoculation with Hao 2018 raised the pH of the soil, the activity of several enzymes (alkaline phosphatase, urease, and dehydrogenase), the nitrogen content (NH4 +-N and NO3 --N), and the pakchoi quality (Vc and soluble protein content), while also raising the relative abundance of bacteria that promote plant growth and immobilize metals, such as Streptomyces and Sphingomonas. In conclusion, Hao 2018 reduced the available Pb in soil and pakchoi Pb absorption by increasing the pH and activity of multiple enzymes and regulating microbiome composition in rhizospheric soil.

Effects of Different Sulfur Compounds on the Distribution Characteristics of Subcellular Lead Content in Arabis alpina L. var. parviflora Franch under Lead Stress.

Sulfur plays a vital role in the phytoremediation of lead-contaminated soil. The effects of different sulfur forms (S Na2S, and Na2SO4) on lead (Pb) absorption in hyperaccumulator Arabis alpina L. var. parviflora Franch were studied in a soil pot experiment. The subcellular sulfur and lead enrichment characteristics in A. alpina were studied by adding sulfur in different forms and concentrations (0, 75, and 150 mg·kg-1) to Pb-contaminated soil. The results show that the root and shoot biomass increased by 1.94 times under Na2S and Na2SO4 treatment, and the root-shoot ratio of A. alpina increased 1.62 times under the three forms of sulfur treatments, compared with the control. Sulfur content in cell walls and soluble fractions of the root and shoot of A. alpina significantly increased 3.35~5.75 times and decreased 5.85 and 9.28 times in the organelles under 150 mg·kg-1 Na2SO4 treatment. Meanwhile, Pb content in the root and shoot cell walls of A. alpina significantly increased by 3.54 and 2.75 times, respectively. Pb content in the shoot soluble fraction increased by 3.46 times, while it significantly reduced by 3.78 times in the shoot organelle. Pb content in the root organelle and soluble fraction decreased by 2.72 and 2.46 times. Different forms and concentrations of sulfur had no regularity in the effect of Pb and sulfur content in the subcellular components of A. alpina, but the bioconcentration and translocation factors of A. alpina increased compared with the control. Under different concentrations of Na2SO4, there was a significant positive correlation between the contents of sulfur and Pb in the subcellular components of the root of A. alpina (p < 0.05). These results indicate that sulfur application can enhance the Pb resistance of A. alpina by strengthening the cell wall fixation and vacuolar compartmentalization.

Influence of Agaricus bisporus Mushroom on Pb Toxicokinetic in Pregnant Rats.

(Pb) is a toxic metal, responsible for several damages to human health. Agaricus bisporus (Ab) is a mushroom with promising antioxidant properties to be used as an alternative chelator in Pb intoxication. The aim was to understand the Pb toxicokinetic and the potential of Ab as a protective agent. A total of 20 female Wistar rats were distributed into 4 groups (n = 5/group): Control (receiving water); Group Ab 100 mg/kg (gavage); Group Pb 100 mg/L in water; and Group Ab + Pb-100 mg/kg + 100 mg/L (gavage and water). Pb administration occurred daily until the 19th day of pregnancy. On day 19 of gestation, the rats were euthanized, and the blood and tissues were collected for Pb measurement, using an inductively coupled plasma mass spectrometer. The results showed that the levels of Pb in the blood, placenta, and liver of the mothers, and in the brain of the fetuses increased significantly in the Pb group. On the other hand, the combined exposure to Pb + Ab showed a significant decrease in the metal concentration in relation to the Pb group, returning to normal levels. Kidney and bone lead levels also increased significantly in the Pb group. However, in the combined exposure group, levels did not return to the control amounts; there was protection, but the Pb concentration was still significantly higher than in the control. In the brain, no significant differences were observed. In conclusion, we suggest A. bisporus is a natural chelator, because the co-administration of the mushroom was able to interact with Pb ions, minimizing the Pb absorption and distribution. These effects are suggested since A. bisporus have antioxidants and beta glucan that interact with Pb, chelating it and, thus, reducing its toxic effects.