Germination and root elongation bioassays in six different plant species for testing Ni contamination in soil

Determination of Toxicity at Different Trophic Levels of Aqueous Film-Forming Foams (AFFF) Used in Fire Fighting

Aqueous film-forming foams (AFFF), containing perfluorinated surfactants, can reach the environment. The objective of this study was to determine the ecotoxicity of AFFF, according to the type of fire to be fought (A1: 1.05 g.L- 1, A2: 3.15 g.L- 1 and A3: 6.30 g.L- 1), to bioindicators of different trophic levels. For Artemia salina a toxic effect was observed at sample A1 (at concentrations of 100%), A2 (at concentrations above 25%) and A3 (at concentrations above 12.5%). For Lactuca sativa all samples affected the number of germinated seeds, speed and percentage of germination and root length. To the Eisenia fetida earthworm, samples A2 and A3 were considered toxic due to the percent avoidance being 70% and 100%, respectively. In Macaca mullata renal cell culture test, none of the samples were toxic by the MTT test. Therefore, it is necessary to develop methods for the safe use of AFFF by professionals.

In vitro chronic phytotoxicity of heavy metals and metalloids to Lepidium sativum (garden cress)

The paper presents the results of studies on the influence of selected concentrations (10-100 mg L-1) of heavy metals (Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Zn) and metalloids (As, Sb, Se) on the germination and root elongation of garden cress (Lepidium sativum L). There are not many studies on phytotoxicity of heavy metals and metalloids with the complex use of single plant species so far. On the basis of the germination index (GI) and inhibition concentration IC50, the following order of phytotoxicity of the tested elements was determined: Se> As> Hg> Sb > Mo > Cd> Co > Zn > Ni. The other metals showed no phytotoxicity or even stimulating effect. In our study the stimulating effect of the majority of Pb concentrations and the lowest concentrations of Cd and Hg has been revealed. These metals do not play any role in living organisms, however some authors confirm their stimulating effect on plants at low concentrations. Toxic concentration of metals and metalloids calculated as IC50 are lower than the concentration calculated as GI (not phytotoxic). It is well known that seeds are more independent and tolerant to toxicants when they contain reserve substances which are used during the germination period. On the basis of conducted research, high tolerance of L. sativum to heavy metals and metalloids was found, which may indicate its usefulness for phytotoxicity assessment of leachate from contaminated soil or waste (e.g. foundry waste) and its application for bioremediation to manage heavy metal pollution of soils or foundry wastes containing heavy metals and metalloids. The understanding of heavy metal and metalloids toxicity will facilitate bioremediation.

Biochar amendment for reducing the environmental impacts of reclaimed polluted sediments

Dredging activities produce large amounts of polluted sediments that require adequate management strategies. Sediment reuse and relocation can involve several environmental issues, such as the release of CO2 and nitrogen compounds in the environment, the transfer of metals to plant tissues and the persistence of phytotoxic compounds. In this framework, the aim of the present work is to evaluate the use of biochar at different doses, in combination with plant growth, to reduce the environmental impacts polluted dredged sediments. Irrespective to the plant treatment, the amendment of the sediment with the lowest dose of biochar (3%) reduced by 25% the CO2 emissions of the substrate, by 89% the substrate carbon loss and by 35% the amount of nitrogen released into the environment (average values of the three plant treatments). The negative priming effect of biochar on organic matter mineralization can be responsible for the beneficial reduction of carbon and nitrogen release in the environment. The lack of similar effects observed at the higher biochar doses can depend on the low albedo of the biochar particles, causing the substrate warming (+1 °C for highest biochar dose) and accelerating the organic matter mineralization. Finally, shrub growth in combination with 3% biochar was able to offset the CO2 emission of the sediment and to reduce the amount of nitrogen lost. This work provides new insight on the potential benefit related to the biochar amendment of organic matter-rich dredged sediments, suggesting that the use of moderate dose of wood biochar in combination with shrub plantation can reduce the release of CO2 and nitrogen compounds in the environment.

Rapid effective treatment of waxy oily sludge using a method of dispersion combined with biodegradation in a semi-fluid state

Waxy oily sludge (WOS) from petrochemical enterprises has complex components and difficult treatment. Long-term large-scale stacking has seriously threatened human health and the ecological environment. In this paper, a new rapid and effective treatment method combining dispersion and biodegradation in a semi-fluid state was developed for the WOS. The degradation mechanism of the WOS in the bioreactor was preliminarily discussed. The component analysis results showed that the compounds with large molecular weight (M ≥ 282) in the WOS accounted for more than 50%. Among all microbial consortiums, the treatment effect of the consortium FF: NY3 = 9: 1 was the best for treating the crude oil in WOS, which was significantly different from that of a single strain (p < 0.05). Under the optimal nitrogen source NH₄NO₃ and the concentration of rhamnolipid, the developed high-efficiency microbial consortium (FF: NY3 = 9:1) could remove 85% of the total hydrocarbon pollutants in the 20 L semi-fluid bioreactor within 9 days. The degradation characteristics of WOS components in the bioreactor showed that the developed consortium has good degradation ability for n-alkanes (about 90%), middle- (77.35%)/long-chain (72.66%) isomeric alkanes, alkenes (79.12%), alicyclic hydrocarbons (78.9%) and aromatic hydrocarbons (62.78%). The kinetic analysis results indicated that, in comparison, the middle-chain n-alkanes, middle-chain isomeric saturated alkanes, alkenes, and alicyclic hydrocarbons were most easily removed. The removal rates of long-chain n-alkanes, long-chain isomeric saturated alkanes, and aromatic hydrocarbons were relatively low. The biological toxicity test showed that the germination rate of wheat seeds in treated waxy sludge was Significantly higher than that in untreated waxy sludge (p < 0.01). These results suggest that the new method developed in this paper can treat refractory WOS quickly and effectively. This method lays the foundation for the pilot-scale treatment of the semi-fluid bioreactor.

Assessment of Phytotoxicity of Landfilled Waste and Foundry Dust Based on The Direct Test

The article presents the results of phytotoxicity tests on foundry dust and landfilled waste. Currently, all this waste is being reused. The research has focused on phytotoxicity tests performed directly on the waste. Garden cress (Lepidium sativum L.) was used as the test plant. The germination test (GI) and the accumulation test were used to assess phytotoxicity. All dust types were highly phytotoxic to L. sativum L. in the direct test. The reason for this effect could be the low pH, the high level of heavy metals (HM), and probably the presence of organic pollutants (phenol, formaldehyde). The most phytotoxic was electric arc furnace dust (EAFD), classified as hazardous waste due to the high content of HM. The landfilled foundry waste (LFW) was characterised by moderate phytotoxicity in the direct test. The study confirmed the usefulness of the direct test in the phytotoxicity assessment of foundry waste with L. sativum L.

High-throughput screening paradigms in ecotoxicity testing: Emerging prospects and ongoing challenges

The rapidly increasing number of new production chemicals coupled with stringent implementation of global chemical management programs necessities a paradigm shift towards boarder uses of low-cost and high-throughput ecotoxicity testing strategies as well as deeper understanding of cellular and sub-cellular mechanisms of ecotoxicity that can be used in effective risk assessment. The latter will require automated acquisition of biological data, new capabilities for big data analysis as well as computational simulations capable of translating new data into in vivo relevance. However, very few efforts have been so far devoted into the development of automated bioanalytical systems in ecotoxicology. This is in stark contrast to standardized and high-throughput chemical screening and prioritization routines found in modern drug discovery pipelines. As a result, the high-throughput and high-content data acquisition in ecotoxicology is still in its infancy with limited examples focused on cell-free and cell-based assays. In this work we outline recent developments and emerging prospects of high-throughput bioanalytical approaches in ecotoxicology that reach beyond in vitro biotests. We discuss future importance of automated quantitative data acquisition for cell-free, cell-based as well as developments in phytotoxicity and in vivo biotests utilizing small aquatic model organisms. We also discuss recent innovations such as organs-on-a-chip technologies and existing challenges for emerging high-throughput ecotoxicity testing strategies. Lastly, we provide seminal examples of the small number of successful high-throughput implementations that have been employed in prioritization of chemicals and accelerated environmental risk assessment.

Marine bacteria-based polyvinyl chloride (PVC) degradation by-products: Toxicity analysis on Vigna radiata and edible seaweed Ulva lactuca

Biodegradation of polyvinyl chloride (PVC) by marine bacteria is a sustainable approach that leads to the production of different by-products but their toxicity needs to be evaluated. In the present study, polyvinyl chloride degradation products (PVCDP) produced by three marine bacterial isolates (T-1.3, BP-4.3 and S-237) in the culture supernatant were evaluated for toxicity on the germination of Vigna radiata and growth of Ulva lactuca. A total of 24 compounds comprising of benzene, fatty acid, ether, ester and plastic stabilizer (tris (2, 4-di-tert-butylphenyl) phosphate) were identified by GC-MS using diethyl ether solvent extraction from the supernatant. The per cent germination rate of the seed treated with PVCDP showed no significant effect but germination index and elongation inhibition rate were influenced significantly by PVCDP treatments. In seaweed (U. lactuca), PVCDP showed improvement in the daily growth rate. After ten days of treatment with PVCDP, pigment contents were improved in seaweed and PVCDP (2%) of isolate T-1.3 recorded the highest chlorophyll-a and chlorophyll-b.

New Evidence of Model Crop Brassica napus L. in Soil Clean-Up: Comparison of Tolerance and Accumulation of Lead and Cadmium

The potential of the model crop Brassica napus L. (rapeseed) for the phytoremediation of soils polluted with metals was investigated at laboratory scale. The first step consists in the evaluation of the seed germination and growth of the Brassica napus L. plant in a controlled environment, followed by the determination of the photosynthetic pigments content represented by chlorophyll a and b and carotenoids. The degree of metal accumulation in rapeseed has been evaluated by the bioaccumulation factor (BAC), the bioconcentration factor (BCF) and the translocation factor (TF). Phytotoxicity tests were performed in Petri dishes with filter papers moistened with metal solutions in the range of 0 to 300 mg/L Pb(II) or Cd(II). At the highest concentration of the lead and cadmium treatments (300 mg/L), B. napus L. showed the lowest germination degree (56.67% and 43.33%, respectively). According to Tukey test results, Pb(II) concentrations of up to 300 mg/L do not significantly affect the length of the hypocotyls, whereas, in the case of Cd(II), the mean of the radicle and hypocotyl lengths of the seedlings are significantly affected compared to the mean of the control. In soil pot experiments, important changes have been obtained in the pigment content, especially in the case of cadmium. For both metals and for each treatment (100 to 1500 mg/kg Pb(II) and 1 to 30 mg/kg Cd(II)), a TF < 1 indicates an ineffective metal transfer from root to shoot. Finally, rapeseed can be considered a tolerant plant and a suitable candidate for Pb(II) and Cd(II) accumulation and for the phytostabilization of contaminated soil under the experimental conditions adopted in the present study.

Toxicity evaluation of the metabolites derived from the degradation of phenanthrene by one of a soil ubiquitous PAHs-degrading strain Rhodococcus qingshengii FF

Rhodococcus qingshengii strain FF is a soil ubiquitous strain that has a high polycyclic aromatic hydrocarbons (PAHs) biodegradation capability. In this work, phenanthrene was used as a PAH model compound. The accumulated pattern of the metabolites of phenanthrene by strain FF was investigated, and their toxicity to Vibrio fischeri, effect on microbiota diversity of farmland soil and influence on seed of wheat were evaluated. Total of 29 main intermediates were observed for the phenanthrene degradation process. Pyrogallol was the predominant accumulated metabolite, and 59% of the accumulated metabolites were oxygen-containing PAHs that have only one benzene ring. The acute toxicity assessment showed the accumulated metabolites in later phase were more toxic to Vibrio fischeri. Microbe and wheat seed response to the different stages of phenanthrene metabolites indicated pollution significantly decreased microbial richness and evenness of farmland soil and lower germinal length, root length or root number of wheat seed. These results indicated that not only the elimination of PAHs, but also the easily accumulated metabolites produced during the PAHs degradation process should be paid enough attention. The comprehensive evaluation of toxicity during the degradation process would provide useful information for the use of microbe-orientated strategies in PAHs bioremediation.

Effects of organic matter addition on chronically hydrocarbon-contaminated soil

Soil is the recipient of organic pollutants as a consequence of anthropogenic activities. Hydrocarbons are contaminants that pose a risk to human and environmental health. Bioremediation of aging contaminated soils is a challenge due to the low biodegradability of contaminants as a result of their interaction with the soil matrix. The aim of this work was to evaluate the effect of both composting and the addition of mature compost on a soil chronically contaminated with hydrocarbons, focusing mainly on the recovery of soil functions and transformations of the soil matrix as well as microbial community shifts. The initial pollution level was 214 ppm of polycyclic aromatic hydrocarbons (PAHs) and 2500 ppm of aliphatic hydrocarbons (AHs). Composting and compost addition produced changes on soil matrix that promoted the release of PAHs (5.7 and 15 % respectively) but not the net PAH elimination. Interestingly, composting stimulated AHs elimination (about 24 %). The lack of PAHs elimination could be attributed to the insufficient PAHs content to stimulate the microbial degrading capacity, and the preferential consumption of easily absorbed C sources by the bacterial community. Despite the low PAH catabolic potential of the aging soil, metabolic shift was driven by the addition of organic matter, which could be monitored by the ratio of Proteobacteria to Actinobacteria combined with E₄/E₆ ratio. Regarding the quality of the soil, the nutrients provided by the exogenous organic matter contributed to the recovery of the global functions and species diversity of the soil along with the reduction of phytotoxicity.

Nanoscale Zero-Valent Iron Has Minimum Toxicological Risk on the Germination and Early Growth of Two Grass Species with Potential for Phytostabilization

Two Poaceae species, Agrostis capillaris and Festuca rubra, were selected for their potential as phytostabilizing plants in multicontaminated soils. These species are resistant to contamination and maintain high concentrations of contaminants at the root level. Nanoscale zero-valent iron (nZVI) is an engineered nanomaterial with the ability to stabilize metal(loid)s in soils; its potential toxicological effects in the selected species were studied in a germination test using: (i) control variant without soil; (ii) soil contaminated with Pb and Zn; and (iii) contaminated soil amended with 1% nZVI, as well as in an hydroponic experiment with the addition of nZVI 0, 25, 50 and 100 mg L⁻¹. nZVI had no negative effects on seed germination or seedling growth, but was associated with an increase in shoot growth and reduction of the elongation inhibition rate (root-dependent) of F. rubra seedlings. However, applications of nZVI in the hydroponic solution had no effects on F. rubra but A. capillaris developed longer roots and more biomass. Increasing nZVI concentrations in the growing solution increased Mg and Fe uptake and reduced the Fe translocation factor. Our results indicate that nZVI has few toxic effects on the studied species.

Assessment of phytotoxicity of leachates from landfilled waste and dust from foundry

The study assesses the contamination, classification and phytotoxicity of foundry waste. The presented results are a part of the research on the agrotechnical use of foundry waste. Landfilled foundry waste (LFW) and dust samples were taken from one of the Polish foundries. An analysis of the waste and its leachate composition was conducted. Phytotoxicity tests were carried out using Lepidium sativum. The aim of the phytotoxicity study was to evaluate germination and root growth after 72 h and the accumulation of heavy metals after 7 days. LFW was least contaminated with heavy metals and metalloids compared to dust. The composition of the foundry dusts depended on the unit of the foundry, from which it was collected. It was found that electric arc furnace dust (EAFD) was the most polluted by heavy metals among the dust samples. According to the requirements of Polish regulations most of tested waste were classified as non-hazardous, and EAFD as hazardous waste due to high Pb concentration in leachate. Phytotoxicity tests have shown a low phytotoxicity of the leachate from most of the tested waste. The results of the accumulation test showed that an excess of metal and metalloids in leachate was not directly related to its accumulation in plants. A negative correlation between EC, Cu, Co, Fe, Pb, Cr, K, Na, sulfate, fluoride, ammonia, phenol and formaldehyde concentration in leachate and GI was found. It was stated that the Fe, Mn, As and Se in plants was significantly correlated with concentrations in leachate.

Toxicity evaluation of olive oil mill wastewater and its polar fraction using multiple whole-organism bioassays

Olive mill wastewater (OMW) as a by-product of olive oil extraction process has significant polluting properties mainly related to high organic load, increased COD/BOD ratio, high phenolic content and relatively acidic pH. Raw OMW from Slovenian Istria olive oil mill and its polar fraction were investigated in this study. Chemical characterization of OMW polar fraction identified tyrosol as the most abundant phenolic product, followed by catechol. Lethal and sub-lethal effects of OMW matrix and its polar fraction were tested using a battery of bioassays with model organisms: bacteria Vibrio fischeri, algae Chlorella vulgaris, water fleas Daphnia magna, zebrafish Danio rerio embryos, clover Trifolium repens and wheat Triticum aestivum. Raw OMW sample was the most toxic to V. fischeri (EC₅₀ = 0.24% of OMW sample final concentration), followed by D. magna (EC₅₀ = 1.43%), C. vulgaris (EC₅₀ = 5.20%), D. rerio (EC₅₀ = 7.05%), seeds T. repens (EC₅₀ = 8.68%) and T. aestivum (EC₅₀ = 11.58%). Similar toxicity trend was observed during exposure to OMW polar fraction, showing EC₅₀ values 2.75-4.11 times lower comparing to raw OMW. Tested samples induced also sub-acute effects to clover and wheat (decreased roots, sprouts elongation); and to zebrafish embryos (increased mortality, higher abnormality rate, decreased hatching and pigmentation formation rate). A comprehensive approach using a battery of bioassays, like those used in this study should be applied during ecotoxicity monitoring of untreated and treated OMW.

Evaluation of the phytotoxicity of coal ash on lettuce (Lactuca sativa L.) germination, growth and metal uptake

Land application of coal ash is considered an environmentally friendly option to improve soil quality, but limited information exists on metal bioavailability and phytotoxicity of coal ash to sensitive plant species such as lettuce (Lactuca sativa L.). Germination and pot bioassay experiments were conducted at six coal application rates (0% (control), 5%, 15%, 25%, 50% and 75% v/v) to investigate the hypothesis that, coal ash will have a hormetic effect on germination, growth, metal uptake and biomass yield of lettuce, characterized by stimulatory and phytotoxicity effects at low and high application rates, respectively. Total concentrations (mg/kg) of metals in coal ash spanned several orders of magnitude, and decreased in the order: Fe (5150.5), Mn (326.0), Zn (102.6), Cu (94.7), Ni (74.7) and Pb (11.6). Bioavailable concentrations of metals were very low (0.0-14.1 mg/kg), accounting for less than 2% of the total concentrations. Coal ash had no significant effect on germination indices, but had hormetic effects on radicle elongation, evidenced by stimulatory and phytotoxicity effects at low (5-25%) and high (50-75%) application rates, respectively. Coal ash application at 50% and 75% significantly (p < 0.05) reduced lettuce growth and edible biomass yield, but lower application rates (5-25%) were similar to the unamended soil (control). Fe, Mn, Zn, Cu and Ni bioavailability and plant uptake generally decreased with increasing coal ash application rates particularly at 50% and 75%. Soil pH significantly increased (p < 0.05) from 6.5 for the control to about 8 for 75% coal ash, while electrical conductivity (EC) increased by 2-7 times to about 0.9 and 1.5 dS/m at 50% and 75% coal ash, respectively. Significant inverse linear relationship (p < 0.05; r2 = 0.80) were observed between edible and total biomass yields and EC, suggesting that increased salinity at high coal ash application rates could account for reduced growth and biomass. Partial elemental balances showed that plant uptake of metals was very low, accounting for just less than 2% of the bioavailable concentrations, while the bulk of the metals (98-99%) remained in the soil. In conclusion, the current findings show that coal ash may have hormetic and phytotoxic effects on sensitive plant species, an observation contrary to the bulk of earlier literature documenting beneficial effects of coal ash application to soils. Long-term field studies are required to confirm the current findings based on laboratory and pot bioassay experiments.

Gas chromatography-Mass Spectra analysis and deleterious potential of fungal based polythene-degradation products

Polythene-degradation products (PE-DPs) produced due to two most efficient polythene degrading fungal isolates (Aspergillus terreus strain MANF1/WL and Aspergillus sydowii strain PNPF15/TS) after 60 days of incubation at ambient temperature with continuous shaking were analyzed by employing GC-MS method. Total 24 PE-DPs were recorded in total 4 samples i) control (pH 3.5), ii) Treatment of Aspergillus terreus strain MANF1/WL (pH 3.5), iii) control (pH 9.5) and iv) Treatment of Aspergillus sydowii strain PNP15/TS (pH 9.5). To check the deleterious status of PE-DPs using both the elite fungal isolates at in vitro level, two living systems (Sorghum and Tiger shark) were used. The percent germination rate of sorghum seeds were found unaffected with PE-DPs of both elite fungi. PE-DPs of both the fungal isolates exhibited maximum germination index at 50%. Whereas, highest elongation inhibition rate (34.75 ± 7.10) was reported with PE-DPs of Aspergillus terreus strain MANF1/WL. In case of animals system, no mortality of the Tiger sharks was documented after fifteen days of the treatment.

Phytotoxicity of wear debris from traditional and innovative brake pads

Traffic-related emissions include gas and particles that can alter air quality and affect human and environmental health. Limited studies have demonstrated that particulate debris thrown off from brakes are toxic to higher plants. The acute phytotoxicity of brake pad wear debris (BPWD) investigated using cress seeds grown in soil contaminated with increasing concentrations of debris. Two types of pads were used: a commercially available phenol based pad and an innovative cement-based pad developed within of the LIFE+ COBRA project. The results suggested that even through the BPWD generated by the two pads were similar in and morphology, debris from traditional pads were more phytotoxic than that from cementitious pads, causing significant alterations in terms of root elongation and loss of plasma membrane integrity.

Leachate phytotoxicity of flue gas desulfurization residues from coal-fired power plant

Flue gas desulfurization residues (FGDR) are the main solid wastes produced in coal-fired power plants that can be reused as alternative materials for civil and agricultural applications. However, the pollutants contained in the FGDR might contaminate the local environment, hindering their material reuse. In this study, the physical-chemical characteristics, leaching, and phytotoxicity (Triticum aestivum) of the material were investigated. The FGDR samples were obtained from three pulverized coal-fired power plants in China. Multivariate statistical analyses were used to consider the contributions of the leaching components to the germination index of wheat seeds in the FGDR leachates. The FGDR contained a high percentage of amorphous mass. The ranges of selected metals and micronutrients in the FGDR are As (31.5-63.0 mg/kg), B (574-3090 mg/kg), Ba (2799-3073 mg/kg), Cr (up to 4.73 mg/kg), Cu (0.29-1.38 mg/kg), Mn (136-370 mg/kg), Ni (9.93-22.9 mg/kg), Pb (1.29-7.29 mg/kg), Sr (886-1706 mg/kg), and Zn (335-458 mg/kg). The leaching toxicity of the FGDR leachates was lower than the regulatory limit of the identification standards for hazardous waste, indicating that the FGDR are non-hazardous materials. Metals, especially Ba, Cu, Fe, and Pb, as well as As and B, in the leachate had inhibitory effects on seed germination than the other constituents. The results in this study showed that the leachate phytotoxicity resulting from FGDR could be evaluated before the utilization of FGDR, giving crucial information for the adaptation of these alternative materials.

Epigenetic modifications preserve the hyperaccumulator Noccaea caerulescens from Ni geno-toxicity

The Ni hyperaccumulator Noccaea caerulescens has adapted to live in a naturally stressed environment, evolving a complex pattern of traits to cope with adverse conditions. Evidence is accumulating regarding the important role of epigenetic modifications in regulating plant responses to stress. In this study, we present data from the natural "open-field" adaptation of the Ni hyperaccumulator N. caerulescens to serpentine soil and provide the first evidence of the involvement of epigenetic changes in response to the high Ni content present in plant leaves. The alkaline comet assay revealed the integrity of the nuclei of leaf cells of N. caerulescens grown in a Ni-rich environment, while in the non-tolerant Arabidopsis thaliana exposed to Ni, the nuclei were severely damaged. DNA of N. caerulescens plants grown in situ were considerably hyper-methylated compared to A. thaliana plants exposed to Ni. In addition, qRT-PCR revealed that N. caerulescens MET1, DRM2, and HDA8 genes involved in epigenetic DNA and histone modification were up-regulated in the presence of high Ni content in leaves. Such epigenetic modifications may constitute a defense strategy that prevents genome instability and direct damage to the DNA structure by Ni ion, enabling plants to survive in an extreme environment. Further studies will be necessary to analyze in detail the involvement of DNA methylation and other epigenetic mechanisms in the complex process of metal hyperaccumulation and plants' adaptive response. Environ. Mol. Mutagen. 59:464-475, 2018. © 2018 Wiley Periodicals, Inc.

Phytotoxicity testing of diesel-contaminated water using Petunia grandiflora Juss. Mix F1 and Marigold-Nemo Mix (Tagetes patula L.)

Tagetes patula (marigold) and Petunia grandiflora (petunia) have been shown to exhibit potential in phytoremediation of environmental pollutants including heavy metals and textile dyes. To investigate their phytoremediation potential of diesel, it was necessary to evaluate diesel phytotoxicity of these two ornamental plants. Marigold and petunia seeds were incubated, for 10 and 15 days, respectively, in deionised water contaminated with 0 to 4%, v/v, diesel in Petri dishes in a growth room with continuous lighting at 25 °C. It was found that as far as seed germination was concerned, petunia was less sensitive than marigold to 4% diesel in water. In contrast, petunia exhibited poorer seedling root growth than marigold in the presence of diesel contamination. This finding of differential sensitivity of these two ornamental plants to diesel-contaminated water during germination and seedling growth has not been reported before. Therefore, the implications of phytotoxicity evaluation and comparison between different species or genotypes of plants at both seed germination and postgermination seedling growth should both be taken into consideration in screening tolerant plants for phytoremediation.

Brassica napus has a key role in the recovery of the health of soils contaminated with metals and diesel by rhizoremediation

Contaminated soils are frequently characterized by the simultaneous presence of organic and inorganic contaminants, as well as a poor biological and nutritional status. Rhizoremediation, the combined use of phytoremediation and bioremediation, has been proposed as a Gentle Remediation Option to rehabilitate multi-contaminated soils. Recently, newer techniques, such as the application of metallic nanoparticles, are being deployed in an attempt to improve traditional remediation options. In order to implement a phytomanagement strategy on calcareous alkaline peri-urban soils simultaneously contaminated with several metals and diesel, we evaluated the effectiveness of Brassica napus L., a profitable crop species, assisted with organic amendment and zero-valent iron nanoparticles (nZVI). A two-month phytotron experiment was carried out using two soils, i.e. amended and unamended with organic matter. Soils were artificially contaminated with Zn, Cu and Cd (1500, 500 and 50mgkg^-1, respectively) and diesel (6000mgkg^-1). After one month of stabilization, soils were treated with nZVI and/or planted with B. napus. The experiment was conducted with 16 treatments resulting from the combination of the following factors: amended/unamended, contaminated/non-contaminated, planted/unplanted and nZVI/no-nZVI. Soil physicochemical characteristics and biological indicators (plant performance and soil microbial properties) were determined at several time points along the experiment. Carbonate content of soils was the crucial factor for metal immobilization and, concomitantly, reduction of metal toxicity. Organic amendment was essential to promote diesel degradation and to improve the health and biomass of B. napus. Soil microorganisms degraded preferably diesel hydrocarbons of biological origin (biodiesel). Plants had a remarkable positive impact on the activity and functional diversity of soil microbial communities. The nZVI were ineffective as soil remediation tools, but did not cause any toxicity. We concluded that rhizoremediation with B. napus combined with an organic amendment is promising for the phytomanagement of calcareous soils with mixed (metals and diesel) contamination.

Lead-Induced Physiological, Biochemical and Enzymatic Changes in Asplenium scolopendrium L

The paper aims to determine the lead-induced physiological, biochemical and enzymatic changes in Asplenium scolopendrium, which could represent biomarkers used in environmental assessment. Of all the physiological processes, photosynthesis and respiration were analyzed and the enzymatic and biochemical determinations focused on catalase activity, assimilatory pigment concentration, polyphenol content and lead presence in tissues.The stress induced by the exposure to Pb of the species Asplenium scolopendrium determined an increase in the carotenoid content, the catalase activity, the total polyphenol content and also enhanced the respiration potential. No significant changes were recorded regarding the chlorophyll content and the photosynthetic activity. The recorded changes may be used as non-specific markers in the assessment of the impact of Pb on plants (Asplenium scolopendrium).

Safety assessment of gasification biochars using Folsomia candida (Collembola) ecotoxicological bioassays

Biochar is a product of the thermal decomposition of biomass under a limited supply of oxygen and can be deriving from pyrolysis or gasification. As the product is rich in highly recalcitrant carbon, it has been proposed as a soil amendment to improve soil fertility and to stock carbon in soils. However, the contaminant compounds present in biochar could represent potential environmental threats. The gasification biochar is a promising by-product, but its effects on soil microarthropods are still nearly unknown. The aim of this study was to assess, using a prognosis approach, any ecotoxicological consequences of four biochars (conifer, poplar, grape marc, and wheat straw) on the springtail Folsomia candida. This was assessed through a series of tests: an avoidance behavior test, a survival and reproduction test, and a test based on the hatching of eggs. Biochars were tested at different concentrations (pulverized and diluted w/w with an artificial standard soil). The results showed that the springtails did not tend to avoid the biochars' substrates up to the rate of 2-5%, but any higher levels of concentration caused the animals to keep away from it. While mortality was negatively affected only in the grape marc biochar, reproduction was significantly reduced in all biochars considered. The hatching of the eggs was anticipated at even the lowest concentrations of herbaceous biochars, while a severe delay was observed in both concentrations tested of the conifer biochar. The endpoints considered were negatively affected by pH, polycyclic aromatic hydrocarbons, and heavy metals (in order of importance). The findings confirmed the potential adverse effects that gasification biochars could have on soil microarthropods and demonstrated the necessity of introducing these tests into biochar characterization protocols.

Impact of plant photosystems in the remediation of benzo[a]pyrene and pyrene spiked soils

The phytoremediation potential of 14 different plant species belonging to C3 and C4 carbon fixation pathway for soils spiked with polycyclic aromatic hydrocarbons (PAHs) such as benzo[a]pyrene (B[a]P) and pyrene (PYR) was investigated. A glasshouse experiment was conducted to measure the changes in morphological, physiological, biochemical parameters and the bioaccumulation and biodegradation ability of the plants in soils spiked with 48 and 194 mg kg^-1 of B[a]P and PYR, respectively. The per cent removal efficacy of B[a]P and PYR by the tested plant species over a period of 50 days was from 6 to 26% and 14 to 40% respectively. The maximum removal of both B[a]P and PYR was observed in Sudan grass (C4), vetiver (C4), maize (C4), and sunflower (C3). In terms of accumulation in root and shoot, the concentration of PYR was higher in both C3 and C4 plant species when compared to B[a]P. Overall the results indicated that C4 plants were more efficient than their C3 counterparts in terms of morphological, physiological, biochemical and degradation ability of PAHs.

Phytotoxicity and groundwater impacts of leaching from thermal treatment residues in roadways

The use of coal fly ash (CFA), municipal solid waste incinerator bottom ash (MSWIBA) and flue gas desulfurization residue (FGDR) in road construction has become very common owing to its economical advantages. However, these residues may contain toxic constituents that pose an environmental risk if they leach out and flow through the soil, surface water and groundwater. Therefore, it is necessary to assess the ecotoxicity and groundwater impact of these residues before decisions can be made regarding their utilization for road construction. In this study, the physico-chemical characteristics, leaching and phytotoxicity of these residues were investigated. Specifically, multivariate analyses were used to evaluate the contributions of the leaching constituents of the CFA, MSWIBA and FGDR leachates to the germination index of wheat seeds. B, Ba, Cr, Cu, Fe and Pb were found to be more toxic to the wheat seeds than the other heavy metals. Furthermore, the leached concentrations of the constituents from the CFA, MSWIBA and FGDR were below the regulatory threshold limits of the Chinese identification standard for hazardous wastes. Analyses conducted using a numerical groundwater model (WiscLEACH) indicated that the predicted field concentrations of metals from the CFA, MSWIBA and FGDR increased with time up to about 30years at the point of compliance, then decreased with time and distance. Overall, this study demonstrated that the risks resulting from MSWIBA, CFA and FGDR leaching could be assessed before its utilization for road construction, providing crucial information for the adoption of these alternative materials.

Bacteria-based polythene degradation products: GC-MS analysis and toxicity testing

Polythene degradation leads to the production of various by-products depending upon the type of degradation process. The polythene degradation products (PEDP) in the culture supernatant of the two bacteria (Lysinibacillus fusiformis strain VASB14/WL and Bacillus cereus strain VASB1/TS) were analyzed with GC-MS technique. The major by-products in the PEDP in the culture supernatant of L. fusiformis strain VASB14/WL (1,2,3,4 tetra methyl benzene) and B. cereus strain VASB1/TS (1,2,3 trimethyl benzene, 1 ethyl 3,5-dimethyl benzene, 1,4 di methyl 2 ethyl benzene, and dibutyl phthalate) dissolved in diethyl ether were recorded. To assess the environmental applicability of polythene degradation using L. fusiformis strain VASB14/WL and B. cereus strain VASB1/TS at in vitro level. The effect of PEDP produced after 2 months of regular shaking at room temperature on both plants and animal system was studied. No significant decrease in the percent seed germination was recorded with the PEDP of both the bacteria. PEDP produced by L. fusiformis strain VASB14/WL did not report any significant change in germination index (GI) at 10 and 25 %, but least GI (39.66 ± 13.94) was documented at 50 % concentration of PEDP. Highest elongation inhibition rate (53.83 ± 15.71) of Sorghum was also recorded with L. fusiformis and at the same concentration.

Variation of the phytotoxicity of municipal solid waste incinerator bottom ash on wheat (Triticum aestivum L.) seed germination with leaching conditions

Municipal solid waste incinerator bottom ash (MSWIBA) has long been regarded as an alternative building material in the construction industry. However, the pollutants contained in the bottom ash could potentially leach out and contaminate the local environment, which presents an obstacle to the reuse of the materials. To evaluate the environmental feasibility of using MSWIBA as a recycled material in construction, the leaching derived ecotoxicity was assessed. The leaching behavior of MSWIBA under various conditions, including the extractant type, leaching time, liquid-to-solid (L/S) ratio, and leachate pH were investigated, and the phytotoxicity of these leachates on wheat (Triticum aestivum L.) seed germination was determined. Moreover, the correlation between the germination index and the concentrations of various chemical constituents in the MSWIBA leachates was assessed using multivariate statistics with principal component analysis and Pearson's correlation analysis. It was found that, heavy metal concentrations in the leachate were pH and L/S ratio dependent, but were less affected by leaching time. Heavy metals were the main pollutants present in wheat seeds. Heavy metals (especially Ba, Cr, Cu and Pb) had a substantial inhibitory effect on wheat seed germination and root elongation. To safely use MSWIBA in construction, the potential risk and ecotoxicity of leached materials must be addressed.

Acute phytotoxicity of seven metals alone and in mixture: Are Italian soil threshold concentrations suitable for plant protection?

Metals can pollute soils in both urban and rural areas with severe impacts on the health of humans, plants and animals living there. Information on metal toxicity is therefore important for ecotoxicology. This study investigated the phytotoxicity of different metals frequently found as pollutants in soils: arsenic, cadmium, chromium, lead, mercury, nickel and zinc. Cucumber (Cucumis sativus), sorghum (Sorghum saccharatum) and cress (Lepidium sativum) seeds were used as models for other plants used in human nutrition such as cereals, rice, fruits and vegetables. The 72-h germination rate and root elongations were selected as short-term ecotoxicological endpoints in seeds exposed to single metals and mixtures. Metals were spiked onto OECD standard soils in concentrations comparable to current Italian contamination threshold concentrations for residential and commercial soils. Arsenic, chromium, mercury and nickel were the most toxic metals in our experimental conditions, particularly to cress seeds (5.172, 152 and 255.4 mg/kg as 72 h IC50 for arsenic, mercury and nickel respectively). Italian limits were acceptable for plant protection only for exposure to each metal alone but not for the mixtures containing all the metals concentrations expected by their respective legislative threshold. The effects of the mixture were class-specific: trends were comparable in dicots but different in monocots. The response induced by the mixture at high concentrations differed from that theoretically obtainable by summing the effects of the individual metals. This might be due to partial antagonism of the metals in soil or to the formation of complexes between the metals, which reduce the bioavailability of the pollutants for plants.