Heavy Metal Treatment Research Articles

GROWTH CHARACTERISTICS OF ORNAMENTAL JUDAS TREE (Cercis siliquastrum L.) SEEDLINGS UNDER DIFFERENT CONCENTRATIONS OF LEAD AND CADMIUM IN IRRIGATION WATER

Landscape plantations are significantly water demanding in many parts of the world, particularly in dry regions. Adequate water supply is the main limiting factor behind landscape development, maintenance and beauty in such environments. On the other hand, monitoring the growth response of ornamental and landscape plants to irrigation water containing heavy metals can be useful in management and application of municipal wastewaters to these plantations instead of application in edible vegetable crops production, which is common in many urban areas. In the present study, one year old seedlings of Judas tree (Cercis siliquastrum) were irrigated for two years with water containing 0, 15 or 30 mg L–1 of lead (Pb) in absence or presence of cadmium (0 or 5 mg L–1) in a factorial design, and under greenhouse conditions. Heavy metal treatments had no significant effect on leaf SPAD value; however, plants treated with Pb15Cd0 combination had significantly higher SPAD value than Pb30Cd5 combination that showed the lowest leaf SPAD value. Increasing the lead and cadmium levels of irrigation water increased the number of chlorotic and necrotic leaves of plant than control, whereas it reduced the average leaf area and new shoot growth. The control plants or plants treated with lower level of heavy metals showed the highest leaf area and new shoot growth. Leaf photosynthesis rate was significantly reduced in all heavy metal treated plants than control plants, as the lowest amount was in Pb30Cd5 combination treatment. All heavy metal treatments showed higher leaf soluble carbohydrates and proline content than in control plants. Leaf soluble carbohydrates were highest in Pb30Cd0 and Pb30Cd5 treatments, and leaf proline was highest in Pb30Cd5 and Pb15Cd5 treatments. The results indicate that Judas tree is a relatively tolerant species to high concentrations of Pb and Cd in root medium added through the irrigation water, and long term dual application of these heavy metals can have additive harmful effects on plant growth.

Screening of Heavy Metal Tolerant Jute Seeds by Germination Test

Present study was the part of an ongoing green plant based contaminated soil remediation technology. The experiment was conducted in two phases. The 1st phase of the experiment was carried out in the laboratory of the department of Agricultural Chemistry, Bangladesh Agricultural University, Mymensing with a view to screening different varieties of jute seeds against the single and combined toxicity of heavy metals viz. As, Pb, Cd by germination test to select heavy metal tolerant jute seeds. Initially 10 treatments were considered viz. 0.5, 10, 15, 20, 30, 50, 70, 100 and 150 ppm for As, Pb, Cd separately and in combination with As, Cd and Pb. The increased levels of heavy metals significantly decreased the germination percentage, seedling height, shoot and root length, fresh and dry weightof five jute varieties. Among five varieties height germination percentage seedling height, shoot and root length, fresh and dry weight were observed with BINA deshi pat-2 but the seedlings survived up to100 ppm single and combined doses of As, Cd and Pb. Germination and seedlingvigor of other four varieties were much less resistance of heavy metal treatments. After screening, BINA deshi pat-2 was used as a phytoremediant in the second phase of bioremediation process which such carried out in the net house from October 2009 onwards. Other two varieties namely BADC deshi pat (CVL-1) and atom pat-38 were selected from experiment conducted by other researcher. In the 2nd phase number of treatments were reduced to six from ten such as 0, 15, 40, 70, 100 and 150ppm single treatments of the experiment revealed that, seeds of the three varieties germinated in toxic soil environment but their primary growth was not satisfactory. Reasons behind the stunted growth might be due to off-season and unfavorable environmental condition. But our idea was to grow jute in successive seasons in a year. BINA deshi pat-2 though photosensitive variety but in pot trial in off season from October, 2009 onwards failed to grow at minimum height not only at toxic condition but also in non toxic soil i.e. in control treatment.

Photoelectrochemical immunosensor for N6-methyladenine detection based on Ru@UiO-66, Bi2O3 and Black TiO2

A novel photoelectrochemical (PEC) immunosensor was successfully constructed for N6-methyladenine (m6A) detection based on the photoactive materials of black titanium dioxide (B-TiO2) and bismuth trioxide (Bi2O3) and the signal amplification unit of [Ru(bpy)3]2+-doped metal organic framework (MOF). The Bi2O3/B-TiO2/ITO electrode was first fabricated, then decorated with gold nanoparticles (AuNPs) which provided sites for anchoring m6A antibodies. After the capture of m6A via immunoreaction with the antibody, the Zr-based metal organic framework (UiO-66)-[Ru(bpy)3]2+ compound was further attached specifically to the phosphate group of m6A. With visible light irradiation, a large and stable photocurrent response was produced in the presence of ascorbic acid (AA). Under optimized experimental conditions, the linear range of the PEC biosensor was 0.05–30 nM, with a low detection limit of 0.0167 nM (S/N = 3). This method showed high specificity, selectivity, stabilization and repeatability. Moreover, it was successfully used for the detection of m6A in rice seedling leaves that had been subjected to heavy metal treatment during their development.

The Role of the Late Embryogenesis-Abundant (LEA) Protein Family in Development and the Abiotic Stress Response: A Comprehensive Expression Analysis of Potato (Solanum Tuberosum).

Late embryogenesis-abundant (LEA) proteins are a large and highly diverse family believed to function in normal plant growth and development, and in protecting cells from abiotic stress. This study presents a characterisation of 74 Solanum tuberosum LEA (StLEA) proteins belonging to nine groups. StLEA genes have few introns (≤2) and are distributed on all chromosomes, occurring as gene clusters on chromosomes 1, 2, and 10. All four StASR (StLEA7 group) genes were concentrated on chromosome 4, suggesting their evolutionary conservation on one chromosome. Expression profiles of StLEA genes, in different tissues and in response to hormone and stress treatments, indicated that 71 StLEA genes had differential expression levels, of which 68 StLEA genes were differentially expressed in response to hormones and stress exposure in the potato. Continuous high expression of StASR-2, StLEA3-3, StDHN-3, StLEA2-29, and StLEA2-14 in different tissues indicated their contribution to plant development processes. StLEA2-14, StLEA2-31, StLEA3-3, StASR-1, and StDHN-1 were upregulated by six abiotic stresses, showing their tolerance to a wide spectrum of environmental stresses. Expression analysis of 17 selected StLEA genes in response to drought, salt, heavy metal, heat, and cold treatments by quantitative real-time polymerase chain reaction indicated that StLEA proteins may be involved in distinct signalling pathways. Taken together, StLEA3, StDHN, and StASR subgroup genes may be excellent resources for potato defence against environmental stresses. These results provide valuable information and robust candidate genes for future functional analysis aimed at improving the stress tolerance of the potato.

Effect of plant growth promoting bacterium; Pseudomonas putida UW4 inoculation on phytoremediation efficacy of monoculture and mixed culture of selected plant species for PAH and lead spiked soils

Plant growth promoting bacteria (PGPB) enhanced phytoremediation (PEP) is an attractive remedial strategy for the remediation of polycyclic aromatic hydrocarbon (PAH) and heavy metal (HM) contaminated sites. The effect of PGPB; Pseudomonas putida UW4 inoculation on the phytoremediation efficiency of Medicago sativa, Festuca arundinacea, Lolium perenne, and mixed plants (L. perenne and F. arundinacea) was assessed. This involved two contaminant treatments; “PAH” (phenanthrene; 300 mg·kg−1, fluoranthene; 200 mg·kg−1, and benzo[a]pyrene; 5 mg·kg−1) and “PAH + HM” (‘PAH’ treatments +100 mg of Pb/kg). PGPB inoculation significantly enhanced root biomass yield of F. arundinacea in PAH treatment, and the mixed plant shoot biomass and L. perenne root biomass yields of the PAH + HM treatment. PGPB significantly enhanced dissipation of phenanthrene and fluoranthene for M. sativa-PAH + PGPB treatment and fluoranthene for F. arundinacea-PAH + HM + PGPB treatment. In others, PGPB inoculation either had no impact or inhibited PAH dissipation. PAH dissipation for the single and mixed plant treatments with PGPB inoculation were not different. The efficiency of PEP is dependent on different factors such as PGPB inoculum biomass, plant species, plant–microbe specificity and type of contaminants. Exploiting PEP technology would require proper understanding of plant tolerance and growth promoting mechanisms, and rhizosphere activities.

Heavy Metal Treatment of Municipal Wastewater Based on Chemical Oxidation

In this paper, based on the existing research, one innovative method for synthesizing poly(m-phenylenediamine) (PmPD) polymer using the chemical oxidation was presented, and the prepared PmPD was used for the treatment of chromium in wastewater. Then, the mechanism of PmPD in the treatment of chromium was studied. The results show that the best method for PmPD synthesis is the drop-by-drop method; 25 °C is the optimum polymerization temperature of PmPD and 5h response time is the optimal synthesis time of the polymer. At pH=2, the removal rate of chromium from wastewater by PmPD polymer reaches more than 80%, and the removal effect of PmPD(Na2CO3)2 on chromium is the best. At pH>7 (the alkaline solution), the PmPD polymer has almost no effect on the removal of chromium. With the same amount of PmPD polymer, the higher the temperature, the better the removal rate of chromium ion by PmPD polymer; the higher the initial chromium ion concentration, the lower the chromium ion removal rate.

Removal of Mn(VII) from Industrial Wastewater by using Alginate-Poly(vinyl) alcohol as Absorbent

An alternative heavy metal treatment method using a low cost absorbent for aqueous medium was studied. Calcium alginate was used as the absorbent together with Poly(vinyl)alcohol for manganese, Mn(VII) extraction from industrial wastewater. The prepared Alginate and Alginate/PVA beads were characterized and the performance of Mn(VII) extraction process by the beads was evaluated in terms of the Mn(VII) extraction efficiency. The adsorption experiments indicate that the amount of adsorbed Mn(VII) improved in addition of PVA with percentages removal up to 65% from the industrial wastewater. As a result, the extraction process proposed was suggested to be simple, safe, and environment-friendly for treating an industrial wastewater. However, further study need to be carried out to gain the concrete information and evidence.

Characterization of Recombinant Phascolosoma esculenta Ferritin as an Efficient Heavy Metal Scavenger.

With economic development, the amount of industrial wastewater discharged with heavy metal ions increases, and heavy metal ion pollution in the environment worsens. Currently, this environmental issue has attracted much attention triggering the development and implication of pollutant binding- or degradation-related genes, especially in heavy metal ion detoxification. Additionally, accumulative results have shown that natural ferritin could store multiple toxic metal ions due to its great storage capacity, resulting in heavy metal detoxification in vivo. In this study, the function of recombinant Phascolosoma esculenta ferritin as an efficient heavy metal scavenger was investigated. In this study, a recombinant ferritin (rferritin) was purified. The structure and heavy metal chelating capacity were examined via SEM, EDS, AFM and ICP-MS. The protection of rferritin on heavy metal toxicity was identified via cell experiments. The rferritin was expressed by E. coli host. The surface morphology and nanoscale structure of rferritin and human ferritin were changed after different heavy metal treatment, and similar protein aggregates were observed under same heavy metal treatment. ICP-MS analysis revealed the enrichment capacity of rferritin varied among different heavy metals and the cell experiments further confirmed that rferritin could protect the bone marrow mesenchymal stem cells against heavy metal toxicity. The rferritin showed an excellent ability to enrich different heavy metals. The adsorption process featured stability, a high yield, simple implementation and low-cost. Thus, the rferritin shows significant potential in the manufacturing of drugs for heavy metal detoxification and environmental remediation.

A Novel Ink‐Stained Paper for Solar Heavy Metal Treatment and Desalination (Solar RRL 10∕2018)

A Novel Ink‐Stained Paper for Solar Heavy Metal Treatment and Desalination (Solar RRL 10∕2018)

Review of Heavy Metal Adsorption Processes by Several Organic Matters from Wastewaters

Heavy metal contamination of natural rivers and wastewaters is a problem for both the environment and human society. The accumulation and adsorption of heavy metals could happen with several organic and inorganic matters, but the most used adsorbents are (biological and chemical) organic compounds. This review article presents the basics of heavy metal adsorption on several organic surfaces. There are many organic matters, which seem to be useful as agents for heavy metal adsorption. All of the cited authors and articles present the adsorption kinetics by the most used isotherm models (such as Langmuir and Freundlich isotherms). By comparing several research results presented by a pre-selected assortment of papers, we would like to give an overview of the microbiological, organic chemical, and other surface adsorption possibilities. We draw conclusions for two new adsorption fields (adsorption with biosorbent and artificial materials). We present an optional possibility to study adsorption kinetics, efficiency and regeneration methods to successfully conclude the heavy metal treatment process, and we make some recommendations about the efficient water usage calculations using the water allowance coefficient (WAC) indicator.

Self-powered light-induced plating of metals on crystalline silicon solar cells

Light induced deposition of metallic Zn, Fe, Co, Ni, Bi, and Cu on crystalline Si solar cell cathodes has been studied as a part of developing self-powered devices. The direct metal deposition relies on the relative position of Si Fermi level and the equilibrium potential of the metal/ion and H+/H2 in electrolyte. Direct deposition of above mentioned metals shows three types of light-induced plating (LIP) behavior. Even with a relative large potential barrier, Cu2+/Cu and Bi3+/Bi could be deposited by the induced plating of the hydrogen evolution. The current density of the Co2+/Co and Ni2+/Ni have been reduced by the light absorption of the electrolyte impact on the solar cell. This work demonstrated the Si solar cells can be used to provide self-powered for metal deposition which can be used in the heavy metal treatment for the polluted water.

Prediction of long-term heavy metal leaching from dredged marine sediment applied inland as a construction material.

Column leaching studies have been suggested as a reference for site-specific prediction of the long-term leaching characteristics of trace constituents in granular materials used as construction materials. In this study, the concept of the long-term leaching prediction using column studies is applied for dredged marine sediment impacted by heavy metals. The column studies show tailing of the liquid to solid ratio-dependent heavy metal leaching for sediment after heavy metal treatment by acid washing. A dual-mode first-order decay model, applied for the first time in this study for column leaching studies, is able to reproduce the leaching characteristics observed. A procedure for long-term leaching prediction using the dual-mode model is developed and applied to a virtual field scenario for which the sediment is beneficially used as a construction material. The prediction results show that by more accurately reproducing the column study results, the dual-mode model generally predicts greater long-term heavy metal loading to the underlying soil layer and longer duration of leaching than the single-mode model. The heavy metal leaching observed in the columns does not show any correlation with the sequential extraction procedure and toxicity characteristic leaching procedure (TCLP) results, suggesting that the column leaching test should be considered to be independent of such batch test procedures.

Determination of Resistance Cumhuriyet-75 and Selimiye-95 Wheat (Triticum Aestivum L.) Varieties Against to Some Abiotic Stress Factories

In this study, resistance mechanism of two wheat genotypes against salt, heavy metal, lime and drought (50%) treatments were investigated in summer Cumhuriyet-75 and winter Selimiye-95. According to results chlorophyll a, b, total chlorophyll and carotenoid level increased in FeCl3, drought and 225 mM NaCl in Cumhuriyet-75 but they were higher at NaCl, FeCl3 and ZnCl2 treatments in Selimiye-95 comparison to control. While H2O2 content rose all stres treatments in both varieties but Malondialdehyde (MDA) decreased in Selimiye with all applications. The amount of proline is lower in Cumhuiyet-75 but higher in Selimiye-95. Total soluble protein was found higher at salt concentartion and drought in both varieties. Ascorbate peroxidase (APX), Süperoxide dismutase (SOD) activity increased in salt and FeCl3 in Selimiye-95 but SOD ativity were higher at salt treatments in Cumhuriyet-75. And also in both varieties APX and Guaiacol peroxidase (GuPX) increased at FeCl3 but Catalase (CAT) were higher in only FeCl3 in Cumhuriyet-75. As a result Selimiye-95 showed tolerance to salt and FeCl3 with high photosynthetic pigment, proline and soluble protein content with lower MDA but it is sensitive to NiCl2 and drought. Whereas Cumhuriyet-75 cultivar is resistan to drought, FeCl3 and 225 mM NaCl depended on pigment, protein content and APX, CAT, GuPX and SOD activities. When all the data are taken into consideration, it was concluded that the responses of the varieties to the treatments changed according to the type and concentration of stress, and Selimiye-95 variety was tolerant compared to Cumhuriyet-75 variety.

A Novel Ink‐Stained Paper for Solar Heavy Metal Treatment and Desalination

High‐performance, flexible and non‐toxic ink‐stained paper is successfully prepared by a two‐step ultrasonic process. Owing to the superior features of light absorption, wettability and heat management via our homemade mimetic tree system, the prepared ink‐stained paper‐black with an average pore size of 2 µm (ISP2‐Black) shows outstanding steam generation performance (85.8% for 1.25 kg m−2 h−1 and 85.5% for 3.70 kg m−2 h−1 at 1 and 3 suns, respectively), and good durability. Furthermore, an outdoor prototype system is realized by fresh water generation up to 1.24 kg m−2 d−1 for direct solar steam generation. Moreover, the ISP2‐Black also exhibits good performance in solar heavy metal treatment and desalination. This work provides a facile method to fabricate ink‐stained paper and a practical route for more cost‐efficient fresh water production and wastewater/polluted water treatment.

Effects of Cd, Zn, or Pb Stress in Populus alba berolinensis on the Antioxidant, Detoxifying, and Digestive Enzymes of Lymantria dispar.

For investigating the physiological responses of herbivores to the heavy metal-stressed woody host plants, the activities of antioxidant, detoxifying, and digestive enzymes in the gypsy moth larvae, Lymantria dispar, that were fed with different heavy metal-stressed poplar seedling (Populus alba berolinensis) leaves were studied. The heavy metal treatments included Cd-treated pot soil (1.5 mg/kg), Zn-treated pot soil (500 mg/kg), and Pb-treated pot soil (500 mg/kg), plus an untreated pot soil as the control. Our results showed that compared with the untreated control, superoxide dismutase (SOD) and catalase (CAT) activities in Cd or Zn treatment group were gradually suppressed with the increases of larval ages, but Pb treatment had no significant effects on SOD activities and significantly increased the CAT activities in both fourth and fifth instar larvae; acid phosphatase (ACP) activities were gradually activated and alkaline phosphatase (AKP) activities were gradually inhibited with the increases of larval ages in Cd or Pb treatment group, but Zn treatment significantly increased the activities of ACP and AKP both in fourth and in fifth instar larvae. All three heavy metals tested did not show any significant effects on the amylase and protease activity in the fourth instar larvae but increased their activities in fifth instar larvae. These results suggest that antioxidant, detoxifying, and digestive enzymes constituted the basic defense system for gypsy moth larvae to resist the toxicity originated from the accumulated Cd, Zn, or Pb in poplar leaves, but their defense level varied with metals investigated and larval developmental stages.

Can water temperature impact litter decomposition under pollution of copper and zinc mixture

AbstractTo better understand the impact of warming on heavy metals (HM) associated with plant litter decomposition in streams, we investigated the impact of high and low HM (Cu and Zn) levels and different water temperatures (10,15 and 20oC) on microbial decomposition ofTyphaangustifoliaL.litter and the associated extracellular enzyme activities. During a 100-day incubation, changes in litter mass losses, chemical composition (lignin and total carbohydrate), and extracellular enzyme activity were determined. The decomposition rates were accelerated by the low HM levels at 20oC (0.0051 day–1at CKvs0.0061 day–1at low HM levels). The negative effects of Cu and Zn onTyphalitter decomposition were more pronounced at lower temperatures (10 and 15°C). The enhanced enzyme activities of cellulase and β-glucosidase and the higher lignin/litter weight loss and lignin/carbohydrate ratios were found at 20oC and low HM treatment. The enzyme activities of β-glucosidase and cellulase were positively correlated with litter mass losses at 20oC and low HM levels. These results suggest that a 5oC increase in water temperature may attenuate the inhibition of low HM level on litter decomposition.

Environmental assessment of heavy metal pollution of Diyala River within Baghdad City

Water quality index (WQI), pollution index (PI), and metal index (MI) were applied in the last reach of Diyala River, Baghdad, Iraq with regard to ten heavy metals (Cd, Cr, Cu, Ni, Pb, Mn, Fe, Zn, Ag, and Cn). These indices were applied to historical data along with the data obtained from the present study in order to acquire a historical heavy metal assessment of the river reach. The results of WQI showed that the water quality of the reach of interest declined from excellent in the year of 1999 to unsuitable in 2007 then good in 2008 to unsuitable once again in the years of 2009–2015. The PI indicated that Cd, Cr, and Pb were the most affecting elements all over the years. The MI was found to be a threshold of warning during all years but with different levels. The impact of Al-Rustimiyah Wastewater Treatment Plants (WWTPs) on the water quality was evident due to the lack of heavy metal treatment units within the plants. It is recommended to add such units to the WWTPs and to reduce the local electricity generators that contribute with great amounts of contaminants.

Assessment of microbial products in the biosorption process of Cu(II) onto aerobic granular sludge: Extracellular polymeric substances contribution and soluble microbial products release

In the present study, the responses of microbial products in the biosorption process of Cu(II) onto aerobic granular sludge were evaluated by using batch and spectroscopic approaches. Batch experimental data showed that extracellular polymeric substances (EPSs) contributed to Cu(II) removal from an aqueous solution, especially when treating low metal concentrations, whereas soluble microbial products (SMPs) were released under the metal stress during biosorption process. A three-dimensional excitation-emission matrix (3D-EEM) identified four main fluorescence peaks in the EPS, i.e., tryptophan protein-like, aromatic protein-like, humic-like and fulvic acid-like substances, and their fluorescence intensities decreased gradually in the presence of Cu(II) during the sorption process. Particularly, tryptophan protein-like substances quenched the Cu(II) binding to a much higher extent through a static quenching process with less than one class of binding sites. According to the synchronous fluorescence spectra, the whole fluorescence intensity of released SMP samples expressed an increased trend with different degrees along with contact time. Two-dimensional correlation spectroscopy (2D-COS) suggested that the fulvic-like fluorescence fraction might be more susceptible to metal exposure than other fractions. The result of molecular weight distribution demonstrated that the SMPs released from the biosorption process differed significantly according to contact time. The result obtained could provide new insights into the responses of microbial products from aerobic granular sludge with heavy metal treatment.

Molecular cloning and characterization of Ipomoea nil metallothioneins

Metallothioneins are low-molecular-weight, cysteine-rich proteins able to bind a variety of heavy metal ions. They are involved in the maintenance of micronutrient homeostasis and detoxification of nonessential heavy metals. Plant metallothioneins are classified into four main types based on the number and arrangement of cysteine residues. Here we report on the isolation of novel complementary and genomic DNA from a model for a short-day plant, Ipomoea nil (Japanese morning glory), that encodes 66- or 76-amino acid residue proteins. In silico and phylogenetic analysis of putative amino acid sequences confirmed that these 66- and 76-amino acid residue proteins belong, respectively, to type 1 and type 2 plant metallothioneins. In genomic sequences of the analyzed metallothioneins, two introns were recognized, one of them located at an evolutionary conserved position. Furthermore, examination of the expression patterns of cloned metallothioneins in I. nil organs and in cotyledons in response to copper and zinc exposure suggested that their physiological functions could be diversified. Moreover, the observed changes of analyzed I. nil metallothioneins in response to heavy metal treatment indicate that InMT1 may be involved in copper homeostasis in I. nil cotyledons. The role of InMT2 in micronutrient homeostasis remains questionable.

Special Issue on Wastewater Treatment and Reuse Technologies

Wastewater treatment allows for the safe disposal of municipal and industrial wastewater to protect public health and the ecosystem[...]