Crop Phytoremediation Research Articles

ANALYSIS OF THE REUSE OF COCONUT WASTE WATER FOR KANGKONG USING A VERTICAL CULTURE HYDROPONIC SYSTEM

Coconut wastewater is the by-product of the coconut milk store. It contains BOD of 9.908,41 mg/L and COD of 38.264,73 mg/L. It can pollute when it is discharged into received water directly. Pollution can prevented by wastewater treatment using phytoremediation method and wastewater reuse for hydroponic crops. This study aimed to determine the effectiveness of the hydroponic system in reducing BOD and COD concentration of coconut wastewater, the effect of the reuse coconut wastewater on crop growth, and to analyze the suitability of coconut wastewater with hydroponic’s standard nutrients. The crop selected in this study was Kangkong (Ipomoea reptans Poir) with a vertical hydroponic system. The retention time was determined based on the Day After Planting (DAP). The DAP ranged in 0 day, 7 days, and 14 days. The crop parameters observed in this study are height, the number of leaves, and gross weight, compared to the controlled crops that use hydroponic’s standard nutrients. The highest reduction of BOD (79,22%) and COD (82,76%) occurs on DAP of 7 days. Crop growth increased as BOD and COD decreased. Initial pollution concentration caused stunted growth, so that the measurement results of phytoremediation crops were below the controlled crops. Coconut wastewater is within the range of standard hydroponic nutrients with 6,16-7,62 pH value, 1.220-1.570 ppm TDS, 2.470-3.180 μS/cm EC, and 25-26oC temperature

The influence of nZVI composites as immobilizing agents on the bioavailability of heavy metals and plant growth in mining metal-contaminated soil

<p>Under the greenhouse scale, nano zero valent iron (nZVI) have been evaluated evaluated by formulation with carboxymethyl cellulose (CMC-nZVI), chitosan (Ch-nZVI), biochar (BC-nZVI), and smectite (SC-nZVI) at rates of 0 and 0.5 and 1% (w/w). The properties of manufactured compounds and their impact on the soil ecosystem planted with safflower (Carthamus tinctorius L.) as a phytoremediation crop for inorganic contaminants in contaminated mining soils have been measured. After 33 days, growth parameters were recorded in harvested plants and the concentrations of some HMs in plant tissues. Furthermore, pH, EC, soluble Na and available Cd, Cu, Pb and Zn concentrations in the treated soil after harvest were analyzed. Results revealed that Ch-nZVI and SC-nZVI application at 0.5% led to a narrow non-significant increase in the dry biomass and the shoot length compared to the control. On the other hand, the application of CMC-nZVI and BC-nZVI resulted in reduced plant growth. All the applied amendments increased soil pH, EC, and soluble Na contents. The soils treated with synthesized nZVI composites showed a considerable increase (non-significant) in available heavy metals in treated soils compared to control. Application of CMC-nZVI1% resulted in increased shoot copper (Cu) and zinc (Zn) (182% and 114%, respectively, compared to control), while Ch-nZVI, SC-nZVI applied at 1%, and BC-nZVI0 applied at 5% resulted in reduce Cu, Zn, and Pb concentrations in roots by 65.2%, 31.4% and 85.5% in Cu, Zn and Pb respectively as compared to control). The phytoremediation indices showed that the uptake and extraction of HMs by safflower plants weren't significant in decreasing heavy metals in polluted soil and the applied materials disabled the actions of hyperaccumulated plant used. Results showed that these materials didn’t have a significant effect on immobilize of HMs in mining soil, while the application of Ch-nZVI, SC-nZVI, and BC-nZVI resulted in disabled hyperaccumulated plant to reducing the uptake of Pb, Cu, and Zn. It could be concluded that the application of synthesized nZVI composites to mining polluted soil might be restricted, mainly due to their negative impacts on soil ecosystem besides their side effects on HMs uptake by test hyperaccumulated crop.</p>

Assessing the Bioaccumulation of Heavy Metals in Cabbage Grown under Five Soil Amendments

Increased heavy metal pollution worldwide necessitates urgent remediation measures. Phytoremediation stands as an eco-friendly technique that addresses this issue. This study aimed to investigate the applicability of phytoremediation in agricultural practices. Specifically, to evaluate the impact of five soil amendments (chicken manure, sewage sludge, leaf compost, cow manure, and vermicompost) on three cabbage (Brassica oleracea var. capitata) varieties (Capture, Primo vantage, and Tiara) yield, quality, and the accumulation of Cd, Cu, Mo, Ni, Pb, and Zn in cabbage heads. The bioaccumulation efficiency of cabbage was determined using an inductively coupled plasma–optical emission spectrometer (ICP-OES). Analysis revealed that soil enriched with chicken manure exhibited the highest cabbage yield. Each cabbage variety demonstrated very high bioaccumulation factor (BAF) indicating substantial heavy metal accumulation. These findings underscore the potential of utilizing crops for phytoremediation to mitigate heavy metal pollution. Additionally, the concentrations of metals below the permissible limits suggest that employing crops for phytoremediation can simultaneously ensure food productivity. This study emphasizes the necessity for further research into the use of crops for remediation strategies.

The impact of acid rain on cadmium phytoremediation in sunflower (Helianthus annuus L.)

Sunflower is an ideal crop for phytoremediation of cadmium-contaminated farmland, as it brings economic benefits while conducting soil remediation. Due to industrial emissions and car exhaust, Cd contaminated areas are often accompanied by acid rain. However, the impact of acid rain on the Cd remediation capacity of sunflowers and its potential influencing factors are unclear. An experiment was manipulated to elucidate the effects of Cd concentration (0,10,50,100 μmol/L) and acid rain (pH 4.0) on the phytoremediation ability of sunflowers, in which the properties of them were explored. The results indicated that Cd stress is the main factor affecting the growth of sunflowers. Without AR, Cd treatment decreased sunflower biomass by 67.5–85.6%. Under AR, Cd treatment decreased sunflower biomass 53.9–86.4%. Compared without AR, the relative chlorophyll content with AR increased by 22.3–23.1%, while the YII with AR decreased by 6.5–20.0%. There was an interaction between acid rain and Cd stress on antioxidant enzyme activity. With AR, CAT activity at 0 μmol/L Cd treatment increased by 25.6%, compared without AR. Whether there is acid rain or not, the POD and SOD activities were increased at 10, 50 μmol/L Cd treatment, but they were decreased at 100 μmol/L Cd treatment. Among them, acid rain exacerbated the impact of POD activity (decreased by 31.4%) at 100 μmol/L Cd treatment and SOD activity (decreased by 15.1%) at 50 μmol/L Cd treatment, compared without AR. In this experiment, the phytoremediation capacity of sunflowers mainly depended on the concentration of Ca in the leaves and their antioxidant capacity. Acid rain enhanced 77.5% the total Cd accumulation at 10 μmol/L Cd treatment, compared without AR. Acid rain exacerbated the damage of Cd to the chloroplast structure of sunflowers, and reduced the accumulation of starch particles. The study findings may be useful for improving the phytoremediation of Cd-contaminated soil.

Genome-wide analysis of metallothionein gene family in maize to reveal its role in development and stress resistance to heavy metal

BackgroundMaize (Zea mays L.) is a widely cultivated cereal and has been used as an optimum heavy metal phytoremediation crop. Metallothionein (MT) proteins are small, cysteine-rich, proteins that play important roles in plant growth and development, and the regulation of stress response to heavy metals. However, the MT genes for maize have not been fully analyzed so far.MethodsThe putative ZmMT genes were identified by HMMER.The heat map of ZmMT genes spatial expression analysis was generated by using R with the log2 (FPKM + 1).The expression profiles of ZmMT genes under three kinds of heavy metal stresses were quantified by using qRT-PCR. The metallothionein proteins was aligned using MAFFT and phylogenetic analysis were constructed by ClustalX 2.1. The protein theoretical molecular weight and pI, subcellular localization, TFs binding sites, were predicted using ProtParam, PSORT, PlantTFDB, respectively.ResultsA total of 9 ZmMT genes were identified in the whole genome of maize. The results showed that eight of the nine ZmMT proteins contained one highly conserved metallothio_2 domain, while ZmMT4 contained a Metallothio_PEC domain. All the ZmMT proteins could be classified into three major groups and located on five chromosomes. The ZmMT promoters contain a large number of hormone regulatory elements and hormone-related transcription factor binding sites. The ZmMT genes exhibited spatiotemporal specific expression patterns in 23 tissues of maize development stages and showed the different expression patterns in response to Cu, Cd, and Pb heavy metal stresses.ConclusionsWe identified the 9 ZmMT genes, and explored their conserved motif, tissue expression patterns, evolutionary relationship. The expression profiles of ZmMT genes under three kinds of heavy metal stresses (Cu, Cd, Pb) were analyzed. In summary, the expression of ZmMTs have poteintial to be regulated by hormones. The specific expression of ZmMTs in different tissues of maize and the response to different heavy metal stresses are revealed that the role of MT in plant growth and development, and stress resistance to heavy metals.

Ramie (Boehmeria Nivea) as Phytoremediation Crop for Heavy Metal-contaminated Paddy Soil in Southern China: Variety Comparison, Cd Accumulation, and Assessment of Fiber Recycling

ABSTRACT Ramie (Boehmeria nivea) is an economic fiber crop that is specifically produced in southern China and faces heavy metal pollution of arable soil. This study investigated the phytoextraction of cadmium (Cd) in seven ramie cultivars, including uptake, translocation, and accumulation differences in organs among cultivars, and assessed the safety of fiber for human health. The obtained results demonstrated that: (1) Zhongzhu No. 3 exhibited the best yield performance, with a fresh bast weight of approximately 343 g in a medium Cd-contaminated paddy field. Leaves accounted for the largest biomass among the parts investigated. (2) Phloem exhibited the highest Cd concentration. Low accumulation and reasonable allocation of Cd enhanced the resistance of ramie to Cd. (3) All varieties exhibited more than 90% Cd removal percentage during the stripping process of fibers. The Cd concentration of the fiber was significantly lower than that of the standard for the fiber industry. Our study provides a new direction for variety breeding in Cd-resistant plants.

Unravelling the distinctive growth mechanism of proso millet (Panicum miliaceum L.) under salt stress: From root‐to‐leaf adaptations to molecular response

AbstractProso millet (Panicum miliaceum L.) has potential applications as a new source of bioenergy owing to its high‐yielding C4 attribute. Besides, it has a short life cycle, high harvest index, low planting costs, and strong adaptability and resistance. This study comprehensively reveals the sodium ion (Na+) toxicity resistance strategies from germination to the seedling stage, root to leaf, outside to inside, macro to micro, and the phenotype to the mechanism. Comparative phenotypic and physiological analysis suggested that salt‐tolerant proso millet (ST 47) had better salt tolerance, biomass accumulation, and osmo‐protection than salt‐sensitive proso millet (SS 212). Microstructural analysis indicated that ST 47 could maintain better internal surfaces and intact structures to resist Na+ toxicity and maintain optimal growth. Further, digital RNA sequence analysis indicated that ST 47 could maintain better Na+ and K+ homeostasis by coordinated regulation of transporter genes; the abundance of transcripts involved in chlorophyll metabolism and photosynthesis pathways was higher in ST 47 than SS 212, which contributed to the biomass accumulation. These results suggest that ST 47 resists Na+ toxicity via coordinated physiological, morphological, and molecular mechanisms. Therefore, this crop can serve as an emerging salt‐tolerant bioenergy crop for sustainable saline agriculture and simultaneous phytoremediation.

Phytoremediation of contaminants of emerging concern from soil with industrial hemp (Cannabis sativa L.): a review

The presence of contaminants of emerging concern (CECs) in wastewater treatment plant effluents is a significant underlying health risk and environmental concern. CECs consist of a wide variety of contaminants, including pharmaceuticals and personal care products, hormones, steroids, alkyl-phenols, flame retardants and pesticides. Their impact is of particular relevance to agricultural settings due to CEC uptake and accumulation in food crops and consequent diffusion into the food-chain. Meanwhile, marijuana reform is accelerating in the US, based on the scope and pace of legalization efforts and on wider acceptance in polls of voters. In this review, the effectiveness of industrial hemp (Cannabis sativa L.) in phytoremediation and hyperaccumulation of organic contaminants (e.g., benzo(a)pyrene, Naphthalene, and Chrysene) and heavy metal (e.g., Selenium and Cobalt) from either aqueous solutions or contaminated soils has been reviewed. The potential of industrial hemp as a renewable resource to biodegrade and/or decontaminate CECs is explored. Disposal strategies of this new phytoremediation crop that promote circular economy are also discussed. According to this current review, we believe the use of industrial hemp for phytoremediation is promising to have a sustainable, environmentally friendly and economically viable future.

Emerging contaminants: Evaluation of degradable chelators towards enhancing cadmium phytoextraction efficiency of bioenergy crop grown on polluted soil

Exogenous application of chelators towards enhancing heavy metals extraction efficiency of bioenergy crop has received considerable attention in recent time. However, little is known about optimal application rate, comparative evaluation of degradable versus non-degradable chelators and their impact on cadmium (Cd) speciation and uptake, physiological and biochemical activity of sweet sorghum grown under Cd stress. Four chelators namely, Nitrilotriacetic acid (NTA), tetrasodium N,N-diacetate (TDA), Ethylenediamine tetraacetic acid (EDTA), iminodisuccinic acid (IDA) and control (CK) were applied and compared at rates of 2, 5, and 10 mmol kg−1 towards augmenting phytoextraction efficiency of sweet sorghum for Cd remediation in a screen house study. Results showed that sweet sorghum augmented with TDA significantly (P < 0.05) increased biomass, enhanced Cd uptake and accumulation when compared to EDTA at application rate of 2–5 mmol kg−1. TDA influenced Cd speciation via increasing acid-soluble, reducible, oxidizable, and residual fractions of Cd, thus increasing Cd bioavailability. NTA and TDA increased proline concentrations, antioxidant enzymes and net photosynthetic activity rate (Pn) comparably to EDTA in sweet sorghum, thus enhancing stress tolerance and stabilizing photosynthetic activities. Overall, exogenous application of degradable TDA at 2–5 mmol kg−1 could be recommended as replacement for non-degradable EDTA in a chelate assisted approach towards augmenting bioenergy crop for phytoremediation of Cd polluted soil.

Potential of hemp (Cannabis sativa L.) for paired phytoremediation and bioenergy production

AbstractHemp (Cannabis sativa L.) is a multi‐use crop that has been investigated for its potential use in phytoremediation of heavy metals, radionuclides, and organic contaminants, and as a feedstock for bioenergy production. A review of research literature indicates that hemp is a suitable crop for phytoremediation, and a competitive option for bioenergy. Coupling phytoremediation and bioenergy production from a single hemp crop is a potential solution to overcoming the economic constraints of phytoremediation projects. The current challenge is ensuring that the extracted contaminants are not introduced into the consumer marketplace. After several decades of limited research on hemp in the United States, the purpose of this review is to identify the knowledge available for hemp applications in phytoremediation or in production of bioenergy, and if and how those two purposes have been combined. The literature shows that hemp growth has been demonstrated successfully at the field scale for phytoremediation and in several bioenergy conversion technologies. Little is known about the fate of contaminants during hemp growth or during post‐harvest processing, especially the relationships between hemp genetics, metabolomics, and contaminant partitioning. Complicating the understanding is the expectation that contaminant fate will be dependent on the contaminant type, the concentration in the material, and the processing methods. Before hemp from phytoremediation applications can be used for bioenergy, the fractionation of heavy metals, radionuclides, and/or organic compounds during transesterification, anaerobic digestion, fermentation, and/or combustion of hemp must be evaluated.

Effects of exogenous sulfur on maize (Zea mays L.) growth and Cd accumulation in Cd-contaminated plastic shed soil.

Cadmium (Cd) pollution in plastic shed soils has become increasingly severe, posing a great threat to human health and social stability. Phytoremediation of cadmium pollution is an environmentally friendly and inexpensive remediation method. In this study, maize (Zea mays L.) was selected as the phytoremediation crop by a potted method, and the bioavailability of cadmium was investigated by adding exogenous elemental sulfur. The relationships among the sulfur content, maize growth, cadmium accumulation, and soil parameters were systematically studied. The results showed that, with the supplement of sulfur, the soil pH and activities of soil enzymes (urease, catalase, and sucrase) decreased gradually, and the available heavy metals (Cd, Cr, Zn, and Cu) in soil showed an upward trend. The optimal cadmium enrichment was achieved under T2 by increasing both the biomass of the maize plant and the cadmium concentration in roots and stems. However, T3 and T4 significantly inhibited the growth of maize roots and shoots, leading to a much lower plant biomass compared with that of CK (sulfur-free treatment) and T2. In addition, the cumulative cadmium was not increased because of the low accumulation of cadmium in some parts of the plant. Correlation analyses showed that the sulfur content was negatively correlated with soil pH and maize biomass (P < 0.01), and the cadmium content of whole maize was positively correlated with the dry weight of maize (P < 0.05) and the cadmium content in roots and stems (P < 0.01). In summary, to optimize cadmium phytoremediation of the plastic shed soil, an appropriate concentration of sulfur should be selected in practical applications to ensure that the biomass of the maize is maximized, and the cadmium concentration in different parts of the maize is increased or stabilized.

Anaerobic digestion of mercury phytoextraction crops with intermediary stage bio-waste polymer treatment

In laboratory experiments, Lepidium sativum L. and Mentha spicata L. were grown in compost spiked with mercury. After cultivation for 20 and 68 days, respectively, translocation factors of 0.05 ≤ TF ≤ 0.2 (Lepidium sativum) and accumulation factors of 2.2 ≤ AF ≤ 12 (Mentha spicata) were recorded. Plants were then harvested and used as feedstock for bench-scale anaerobic digesters. The reactors operated in continuously-stirred batch mode for a period of ten days. Inhibition of anaerobic biogas production was apparent with one sample set evidencing mercury-induced bacteriostatic toxicity. Otherwise, ex-situ characterization of digestate showed that the reactors were within stable operating range. A canola oil-sulphide polymer derived from bio-waste was also used as an intermediary treatment stage to test its capacity for extracting mercury from half the samples prior to anaerobic digestion, and also from the post-experimentation reactor digestate. The polymer removed mercury from digestate with a 40–50% efficacy across all samples, suggesting its potential as a sludge clean-up option. Anaerobic digestion combined with staged polymer extraction offers a potential route for the disposal of phytoremediation crops and ultimately the recovery of mercury, coincident with the production of a bioenergy vector.

The Suitability of Short Rotation Coppice Crops for Phytoremediation of Urban Soils

This experiment was aimed at verifying the usefulness of phytoremediation using Short Rotation Coppice (SRC) in an urban Zn-contaminated site. Besides elemental uptake and reclamation, the SRC method was applied to evaluate the additional benefits of a green infrastructure. Nine different plants with rapid growth and large biomass production were selected: three Populus clones, three Salix hybrids, and three Robinia genotypes. Annual and biennial coppicing were evaluated. Poplar clones were more productive using annual coppicing, while Salix and Robinia produced higher biomass in blocks not coppiced. Poplar had the highest phytoextraction rate during the second year, with 1077 g/ha. Salix clones S1 and S3 extracted similar quantities using biennial coppicing. After two years, the bioavailable fraction of Zn decreased significantly using all species, from the 26% decrease of Robinia to the 36% decrease of Salix. The short rotation coppice method proved to be useful in an urban context, for both landscape and limiting the access to the contaminated area. Improving the biomass yield through the phytomanagement options (fertilization, irrigation, coppicing, etc.) could make SRC phytoremediation an economic and effective solution to manage urban contaminated areas, coupling the added values of biomass production to the landscape benefits.

Co-cropping with three phytoremediation crops influences rhizosphere microbiome community in contaminated soil

Human industrial activities have left millions of hectares of land polluted with trace element metals and persistent organic pollutants (POPs) around the world. Although contaminated sites are environmentally damaging, high economic costs often discourage soil remediation efforts. Phytoremediation is a potential green technology solution but can be challenging due to the diversity of anthropogenic contaminants. Co-cropping could provide improved tolerance to diverse soil challenges by taking advantage of distinct crop capabilities. Co-cropping of three species with potentially complementary functions, Festuca arundinacea, Salix miyabeana and Medicago sativa, perform well on diversely contaminated soils. Here, rhizosphere microbiomes of each crop in monoculture and in all co-cropping combinations were compared using 16S rRNA gene amplification, sequencing and differential abundance analysis. The hyperaccumulating F. arundinacea rhizosphere microbiome included putative plant growth promoting bacteria (PGPB) and metal tolerance species, such as Rhizorhapis suberifaciens, Cellvibrio fibrivorans and Pseudomonas lini. The rhizosphere microbiome of the fast-growing tree S. miyabeana included diverse taxa involved in POP degradation, including the species Phenylobacterium panacis. The well-characterised nitrogen-fixing M. sativa microbiome species, Sinorhizobium meliloti, was identified alongside others involved in nutrient acquisition and putative yet-to-be-cultured Candidatus saccharibacteria (TM7-1 group). The majority of differentially abundant rhizosphere-associated bacterial species were maintained in co-cropping pairs, with pairs having higher numbers of differentially abundant taxa than monocultures in all cases. This was not the case when all three crops were co-cropped, where most host-specific bacterial species were not detected as differentially abundant, indicating the potential for reduced rhizosphere functionality. The crops cultivated in pairs here retained rhizosphere microbiome bacteria involved in these monoculture ecosystem services of plant growth promotion, POP tolerance and degradation, and improved nutrient acquisition. These findings provide a promising outlook of the potential for complementary co-cropping strategies for phytoremediation of the multifaceted anthropogenic pollution which can disastrously affect soils around the world.

Phytoremediation of sewage sludge by Cymbopogon martinii (Roxb.) Wats. var. motia Burk. grown under soil amended with varying levels of sewage sludge

Sewage sludge used as agriculture fertilizers contains a conspicuous amount of potentially toxic metals. In order to prevent the contamination in the food chain, there is an urgent need for the development of sewage sludge clean up technology. The use of non-food, multi-harvest aromatic crops for phytoremediation of sewage sludge has many benefits. Besides the eco-friendly approach, plant biomass generated can be used to extract economically important essential oil free of heavy metals. Cymbopogon martinii was grown in soil (s) amended with different ratios of sewage sludge (ss), that is, 100s:0ss (control), 80s:20ss, 60s:40ss, 40s:60ss, 20s:80ss, and 0s:100ss. The experiment was conducted in a plastic sack under an open environment for 1 year and harvesting was done thrice. Plant growth and essential oil yield were significantly increased with the increasing dose of sewage sludge. Accumulation of toxic metal (Cd, Cr, Pb, Ni) and micronutrient (Fe, Zn, Cu, Mn) increased significantly in the shoot tissues confirmed by estimation of bioaccumulation and bioconcentration, and scanning electron microscopy and X-ray microanalyses. Soil enzyme activities were significantly improved with the plant growth period and increased doses of sludge. Results showed C. martinii acts as hyper-accumulator and thus could be used for phytoremediation of sewage sludge.

SPECIES DIVERSITY OF THE VIR COLLECTION OF GRAIN LEGUME GENETIC RESOURCES AND ITS USE IN DOMESTIC BREEDING

The world’s genebanks hold 7.5 million germplasm accessions of plant genetic resources (PGR). One of the qualitative characteristics of the PGR collections is the species diversity, in particular, the presence of crop wild relatives (CWR), which makes it possible to widen the use of gene pools in the breeding process. The collection of the Vavilov Institute (VIR) is one of the most diverse holdings in the number of plant species. A survey is provided here of the species diversity in VIR’s grain legume collection, and its use in domestic breeding practice is analyzed. Comparison of this diversity with the state of PGR exploitation in the world makes it possible to assess the prospects of more efficient utilization of gene pool potential, especially for species that are unjustifiably cultivated on a too small scale or even neglected as crops in this country. The VIR collection of grain legumes incorporates 196 species from 9 genera of the family Fabaceae. This number includes cultigens and CWR. The cultivars of 21 species of grain legumes listed in the State Register of Breeding Achievements (2018) are adapted to the soil and climate conditions of this country. However, the species diversity of the collection could be used more efficiently in domestic plant breeding and crop production. This concerns both underutilized crops in Russia (broad beans, lima beans and grass pea) and those whose adaptive potential is adjusted only to certain and limited areas of the Russian Federation (Tepary beans and Vigna spp.). It is also necessary to exploit more efficiently species of the wild flora, both for direct utilization as pastures, green manure or phytoremediation crops and for introgressive breeding and domestication (Vicia benghalensis L., V. narbonensis L., Lathyrus sylvestris L., Lupinus hartwegii Lindl., etc.). Incorporation of crop wild relatives into the breeding process is promising for crop improvement in a number of aspects: for example, to increase resistance to diseases, pests, abiotic stressors, etc.

The impact of Pseudomonas putida UW3 and UW4 strains on photosynthetic activities of selected field crops under saline conditions

This research was aimed to assess the photosynthetic activities of barley (Hordeum valgare L.), clover (Trifolium repens L.), and pearl millet (Pennisetum glaucum (L.) R. Br.) under different saline conditions with two strains of Pseudomonas putida (UW3 and UW4) treatments. An exceptional observation was revealed on barley biomass ratio (288.8%) that irrigated with brackish saline water (10,000 mg/L) with the presence of P. putida UW4 strain. In general, P. putida UW3 strain was significantly increased crops biomass ratio (249.4%, 202.1%, and 212.5%) for barley, pearl millet, and clover, respectively, which were irrigated with 10,000 mg/L brackish saline water. Plant root and shoot systems were significantly increased in their length and weight reflecting the improvement of plants’ photosynthetic activities under salt stress conditions with the presence of P. putida strains. The results from pulse amplitude modulation fluorometry showed that the plants were recovered from the saline stress effect once P. putida strains were applied. The outcome of this research was highly recommended to apply P. putida strains (UW3 and UW4) with field crops for phytoremediation, in particular, where salinity (soil and/or brackish water) was environmentally challenging.

Phytoremediation of Heavy Metal-Contaminated Soil by Switchgrass: A Comparative Study Utilizing Different Composts and Coir Fiber on Pollution Remediation, Plant Productivity, and Nutrient Leaching

We investigated the effects of organic amendments (thermophilic compost, vermicompost, and coconut coir) on the bioavailability of trace heavy metals of Zn, Cd, Pb, Co, and Ni from heavy metal-spiked soils under laboratory conditions. To test switchgrass (Panicum virgatum) as a potential crop for phytoremediation of heavy metal from soil, we investigated whether the addition of organic amendments promoted switchgrass growth, and consequently, uptake of metals. Compost is a valuable soil amendment that supplies nutrients for plant establishment and growth, which is beneficial for phytoremediation. However, excess application of compost can result in nutrient leaching, which has adverse effects on water quality. We tested the nutrient leaching potential of the different organic amendments to identify trade-offs between phytoremediation and water quality. Results showed that the amendments decreased the amount of bioavailable metals in the soils. Organic amendments increased soil pH, electrical conductivity (EC), and soil nutrient status. Switchgrass shoot and root biomass was significantly greater in the amended soils compared to the non-amended control. Amended treatments showed detectable levels of heavy metal uptake in switchgrass shoots, while the control treatment did not produce enough switchgrass biomass to measure uptake. Switchgrass uptake of certain heavy metals, and concentrations of some leachate nutrients significantly differed among the amended treatments. By improving soil properties and plant productivity and reducing heavy metal solubility that can otherwise hamper plant survival, organic amendments can greatly enhance phytoremediation in heavy metal-contaminated soils.

Linking phytotechnologies to bioeconomy; varietal screening of high biomass and energy crops for phytoremediation of Cr and Cu contaminated soils

Enerbiochem was a project devoted to study new strategies of industrial valorisation of high biomass crops grown on brownfields or contaminated soils not suitable for food production. Chromium and copper accumulation and toxicity were examined in different species of agronomic interest. Cultivars of Brassica carinata A. Braun (7), Brassica juncea (L.) Czern. (4), Brassica napus L. (4), Raphanus sativus L. (4), inbred lines of Helianthus annuus L. (6) and cultivars of Nicotiana tabacum L. (3) were screened for the best genetic materials to be used with the aims: i) to produce the highest biomass in contaminated soils; and ii) possibly to phytoremediate them. Cr and Cu accumulation in shoots were evaluated on 16 days old plants grown for additional 5 days in the presence of either Cr (60 μM) or Cu (2 μM) in hydroponic. They were characterised for Cr and Cu concentrations in roots and shoots, shoot biomass, and total chlorophyll as well. Shoot biomass was significantly lower in Brassica species than in R. sativus, H. annuus and N. tabacum under Cr treatments. On the contrary, under Cu treatments, N. tabacum produced the lowest biomass in respect to other species. Potentially toxic element concentrations varied among genetic material and some genetic material resulted less affected (higher chlorophyll content and shoot biomass) even under higher Cu or Cr concentrations in shoot. Potential candidates within each species, to be used for coupling phytoremediation and biomass production on slightly Cr-Cu potentially contaminated soils are listed.

Energy crops for sustainable phytoremediation – Fuel characterization

Abstract Two energy crops Miscanthus x giganteus and Sida hermaphrodita were used for a phytoremediation study on two different sites of soil contaminated with heavy metals in Poland and Germany. The energy crops were harvested and characterized with regards to fuel properties and thermal decomposition behaviour. Site influences on the data of proximate and ultimate analyses have been observed. Differences in the thermal decomposition are caused by the differences in pH value and heavy metal content of the soils.