Ecotoxicological assessment of biomass-derived furan platform chemicals using aquatic and terrestrial bioassays.

An environmental toxicological assessment of fourteen furanic compounds serving as valuable building blocks produced from biomass was performed. The molecules selected included well studied compounds serving as control examples to compare the toxicity exerted against a variety of highly novel furans which have been additionally targeted as potential or current alternatives to biofuels, building blocks and polymer monomers. The impact of the furan platform chemicals targeted on widely applied ecotoxicity model organisms was determined employing the marine bioluminescent bacterium Aliivibrio fischeri and the freshwater green microalgae Raphidocelis subcapitata, while their ecotoxicity effects on plants were assessed using dicotyledonous plants Sinapis alba and Lepidium sativum. Regarding the specific endpoints evaluated, the furans tested were slightly toxic or practically nontoxic for A. fischeri following 5 and 15 min of exposure. Moreover, most of the building blocks did not affect the growth of L. sativum and S. alba at 150 mg L-1 for 72 h of exposure. Specifically, 9 and 11 out of the 14 furan platform chemicals tested were non-effective or stimulant for L. sativum and S. alba respectively. Given that furans comprise common inhibitors in biorefinery fermentations, the growth inhibition of the specific building blocks was studied using the industrial workhorse yeast Saccharomyces cerevisiae, demonstrating insignificant inhibition on eukaryotic cell growth following 6, 12 and 16 h of exposure at a concentration of 500 mg L-1. The study provides baseline information to unravel the ecotoxic effects and to confirm the green aspects of a range of versatile biobased platform molecules.

Three Active Phytotoxic Compounds from the Leaves of Albizia richardiana (Voigt.) King and Prain for the Development of Bioherbicides to Control Weeds.

The global population is increasing day by day. To meet the food demand for such a huge number of people, crop production must increase without damaging the environment, and to prevent synthetic chemical herbicides from polluting the environment, controlling weeds using bioherbicides is essential. Accordingly, using phytotoxic substances obtained from plants for biological weed management has attracted attention. The plant Albizia richardiana possesses phytotoxic compounds that have been previously recorded. Hence, we have conducted this research to characterize more phytotoxic compounds in Albizia richardiana. Aqueous methanolic extracts of Albizia richardiana plant significantly restricted the growth of the examined plants lettuce and Italian ryegrass in a species- and concentration-dependent manner. Three active phytotoxic compounds were isolated through various chromatographic methods and identified as compound 1, 2, and 3. Compound 3 exhibited stronger phytotoxic potentials than the other two compounds and significantly suppressed the growth of Lepidium sativum (cress). The concentration of the compounds required for 50% growth reduction (I50 value) of the Lepidium sativum seedlings ranged between 0.0827 to 0.4133 mg/mL. The results suggest that these three phytotoxic compounds might contribute to the allelopathic potential of Albizia richardiana.

Short-term physiological and biometrical responses of Lepidium sativum seedlings exposed to PET-made microplastics and acid rain.

Plastics enter in terrestrial natural system primarily by agricultural purposes, while acid rain is the result of anthropogenic activities. The synergistic effects of microplastics and acid rain on plant growth are not known. In this study, different sizes of polyethylene terephthalate (PET) and acid rain are tested on Lepidium sativum, in two separate experimental sets. In the first one we treated plants only with PET, in the second one we used PET and acid rain together. In both experimentations we analyzed: i) plant biometrical parameters (shoot height, leaf number, percentage inhibition of seed germination, fresh biomass), and ii) oxidative stress responses (hydrogen peroxide; ascorbic acid and glutathione). Results carried out from our experiments highlighted that different sizes of polyethylene terephthalate are able to affect plant growth and physiological responses, with or without acid rain supplied during acute toxicity (6 days). SHORT DESCRIPTION: This study showed that different sizes of PET microplastics affect physiological and biometrical responses of Lepidum sativum seedlings, with or without acid rain; roots and leaves responded differently.

Ecotoxicity profile of heavily contaminated surface water of two rivers in Tunisia.

Persistent organic and inorganic contaminants generated by industrial effluent wastes poses a threat to the maintenance of aquatic ecosystems and public health. The Khniss and Hamdoun rivers, located in the central-east of Tunisia, receive regularly domestic and textile wastewater load. The present study aimed to survey the water quality of these rivers using physicochemical, analytical and toxicological approaches. In the physicochemical analysis, the recorded levels of COD and TSS in both samples exceed the Tunisian standards. Using the analytical approach, several metals and some textile dyes were detected. Indeed, 17 metals were detected in both samples in varying concentrations, which do not exceed the Tunisian standards. The sources of metals pollution can be of natural and anthropogenic origin. Three textile disperse dyes were detected with high levels compared to other studies: the disperse orange 37 was detected in the Khniss river with a concentration of 6.438 µg/L and the disperse red 1 and the disperse yellow 3 were detected in the Hamdoun river with concentrations of 3.873 µg/L and 1895 µg/L, respectively. Textile activities were the major sources of disperse dyes. For both samples, acute and chronic ecotoxicity was observed in all the studied organisms, however, no genotoxic activity was detected. The presence of metals and textile disperse dyes could be associated with the ecotoxicological effects observed in the river waters, in particular due to the industrial activity, a fact that could deteriorate the ecosystem and therefore threaten the human health of the population living in the study areas. Combining chemical and biological approaches, allowed the detection of water ecotoxicity in testing organisms and the identification of possible contributors to the toxicity observed in these multi-stressed water reservoirs.

Potential use of Schumannianthus dichotomus waste: the phytotoxic activity of the waste and its identified compounds.

The phytotoxic potential of the leaves and twigs of Schumannianthus dichotomus, discarded in the mat-making industry against four test plants (lettuce (Lactuca sativa L.), rapeseed (Brassica napus L.), foxtail fescue (Vulpia myuros (L.) C.C. Gmel.) and timothy (Phleum pratense L.)) was investigated and found strong phytotoxic activity. An assay-guided fractionation of S. dichotomus extarcts against cress (Lepidium sativum L.) through a series of column chromatography steps yielded two compounds, 8-(5-oxo-2,5-dihydrofuran-2-yl) octanoic acid (ODFO) and (E)-6-hydroxy-2,6-dimethylocta-2,7-dienoic acid (8-carboxylinalool). ODFO and 8-carboxylinalool showed strong phytotoxic activity against cress and timothy. The concentrations required for 50% growth inhibition (I50 value) of the seedlings of cress and timothy were 111.94-128.01 and 36.30-91.75 µM, respectively, for ODFO, but the values were much higher at 315.98-379.13 and 107.92-148.41 µM, respectively, for 8-carboxylinalool, indicating the stronger phytotoxic activity of ODFO. This study is the first to isolate ODFO and 8-carboxylinalool from S. dichotomus and their phytotoxic potential while ODFO is firstly encountered from any natural source. The growth inhibitory activity of the identified compounds may explain their role in the phytotoxic activity of S. dichotomus, which suggests the possible use of its leaves and twigs or its active constituents as natural bioherbicides.

Decomposition and organic amendments chemistry explain contrasting effects on plant growth promotion and suppression of Rhizoctonia solani damping off.

Organic Amendments (OAs) has been used in agroecosystems to promote plant growth and control diseases caused by soilborne pathogens. However, the role of OAs chemistry and decomposition time on plant growth promotion and disease suppression is still poorly explored. In this work, we studied the effect of 14 OAs at four decomposition ages (3, 30, 100, and 300 days) on the plant-pathogen system Lactuca sativa-Rhizoctonia solani. OAs chemistry was characterized via 13C-CPMAS NMR spectroscopy as well as for standard chemical (i.e. N content, pH, EC) and biological parameters (i.e. phytotoxicity and R. solani proliferation bioassay). OAs have shown variable effects, ranging from inhibition to stimulation of Lactuca sativa and Lepidium sativum growth. We recorded that N rich OAs with high decomposability were conducive in the short-term, while converting suppressive in the long term (300 days). On the other hand, cellulose-rich OAs with high C/N ratio impaired L. sativa growth but were more consistent in providing protection from damping-off, although this property has significantly shifted during decomposition time. These results, for the first time, highlight a consistent trade-off between plant growth promotion and disease control capability of OAs. Finally, we found that OAs effects on growth promotion and disease protection can be hardly predictable based on the chemical characteristic, although N content and some 13C CPMAS NMR regions (alkyl C, methoxyl C, and carbonyl C) showed some significant correlations. Therefore, further investigations are needed to identify the mechanism(s) behind the observed suppressive and conducive effects and to identify OAs types and application timing that optimize plant productivity and disease suppression in different agro-ecosystems.

Magnesium-Isotope Fractionation in Chlorophyll-a Extracted from Two Plants with Different Pathways of Carbon Fixation (C3, C4).

Relatively few studies have been focused so far on magnesium-isotope fractionation during plant growth, element uptake from soil, root-to-leaves transport and during chlorophylls biosynthesis. In this work, maize and garden cress were hydroponically grown in identical conditions in order to examine if the carbon fixation pathway (C4, C3, respectively) might have impact on Mg-isotope fractionation in chlorophyll-a. The pigment was purified from plants extracts by preparative reversed phase chromatography, and its identity was confirmed by high-resolution mass spectrometry. The green parts of plants and chlorophyll-a fractions were acid-digested and submitted to ion chromatography coupled through desolvation system to multiple collector inductively coupled plasma-mass spectrometry. Clear preference for heavy Mg-isotopes was found in maize green parts (∆26Mgplant-nutrient 0.65, 0.74 for two biological replicates, respectively) and in chlorophyll-a (∆26Mgchlorophyll-plant 1.51, 2.19). In garden cress, heavy isotopes were depleted in green parts (∆26Mgplant-nutrient (-0.87)-(-0.92)) and the preference for heavy isotopes in chlorophyll-a was less marked relative to maize (∆26Mgchlorophyll-plant 0.55-0.52). The observed effect might be ascribed to overall higher production of energy in form of adenosine triphosphate (ATP), required for carbon fixation in C4 compared to C3, which could reduce kinetic barrier and make equilibrium fractionation prevailing during magnesium incorporation to protoporphyrin ring.

An Oxygen Delivery Polymer Enhances Seed Germination in a Martian-like Environment.

Critical to the success of establishing a sustainable human presence on Mars is the ability to economically grow crop plants. Several environmental factors make it difficult to fully rely on local resources for agriculture. These include nutrient sparse regolith, low and fluctuating temperatures, a high amount of ultraviolet radiation, and water trapped locally in the form of ice or metal oxides. While the 96% CO2 martian atmosphere is ideal to support photosynthesis, high CO2 concentrations inhibit germination. An added difficulty is the fact that a vast majority of crop plants require oxygen for germination. Here, we report the production of a polymer-based oxygen delivery system that supports the germination and growth of cress seeds (Lepidium sativum) in a martian regolith simulant under a martian atmosphere at 101 kPa. The oxygen-donating system is based on a low-density lightly cross-linked polyacrylate that is foamed and converted into a dry powder. It is lightweight, added in low amounts to regolith simulant, and efficiently donates enough oxygen throughout the volume of hydrated regolith simulant to fully support seed germination and plant growth. Germination rates, plant development, and plant mass are nearly identical for L. sativum grown in 100% CO2 in the presence of the oxygen-donating lightly cross-linked polyacrylate compared with plants grown in air. The polymer system also serves to protect root structures and better anchors plants in the regolith simulant.

Characterization of heavy metal toxicity in some plants and microorganisms-A preliminary approach for environmental bioremediation.

In situ bioremediation processes are important for control of pollution and clean-up of contaminated sites. The study and implementation of such processes can be designed through investigations on natural mechanisms of absorption, biotransformation, bioaccumulation and toxicity of pollutants in plants and microorganisms. Here, the phytotoxic effects of Cr(VI) and Cd(II) on seed germination and plant growth of Lepidium sativum have been examined at various concentrations (30-300 mg/L) in single ion solutions. The studies also addressed the ecotoxicity of metal ions on Azotobacter chroococcum and Pichia sp. isolated from soil. Microbial growth was estimated by weighing the dry biomass and determining the enzymatic activities of dehydrogenase and catalase. The results showed that Cr(VI) and Cd(II) can inhibit L. sativum seed germination and root development, depending on the metal ion and its concentration. The phytotoxic effect of heavy metals was also confirmed by the reduced amounts of dried biomass. Toxicity assays demonstrated the adverse effect of Cr(VI) and Cd(II) on growth of Azotobacter sp. and Pichia sp., manifested by a biomass decrease of more than 50 % at heavy metal concentrations of 150-300 mg/L. The results confirmed close links between phytotoxicity of metals and their bioavailability for phytoextraction. Studies on the bioremediation potential of soils contaminated with Cr(VI) and Cd(II) using microbial strains focusing on Azotobacter sp. and Pichia sp. showed that the microbes can only tolerate heavy metal stress at low concentrations. These investigations on plants and microorganisms revealed their ability to withstand metal toxicity and develop tolerance to heavy metals.

Fungal biodegradation and multi-level toxicity assessment of vinasse from distillation of winemaking by-products.

The wastewaters from distilleries of winemaking by-products, a scarcely studied type of vinasse, were treated by white-rot fungal strains from species Irpex lacteus, Ganoderma resinaceum, Trametes versicolor, Phlebia rufa and Bjerkandera adusta. The main objectives of this study were to evaluate fungal performance during vinasse biodegradation, their enzyme patterns and ecotoxicity evolution throughout treatment. Despite all strains were able to promote strong (>80%) dephenolization and reduction of total organic carbon (TOC), P. rufa was less affected by vinasse toxicity and exhibit better decolorization. In batch cultures at 28 °C and pH 4.0, the first phase of P. rufa biodegradation kinetics was characterized by strong metabolic activity with simultaneous depletion of TOC, phenolics and sugars. The main events of second phase are the increase of peroxidases production after the peak of laccase activity, and strong color removal. At the end of treatment, it was observed highly significant (p < 0.001) abatement of pollution parameters (83-100% removal). Since water reclamation and reuse for e.g. crop irrigation is a priority issue, vinasse ecotoxicity was assessed with bioindicators representing three different phylogenetic and trophic levels: a marine bacterium (Aliivibrio fischeri), a freshwater microcrustacean (Daphnia magna) and a dicotyledonous macrophyte (Lepidium sativum). It was observed significant (p < 0.05) reduction of initial vinasse toxicity, as evaluated by these bioindicators, deserving special mention an almost complete phytotoxicity elimination.

Antimicrobial and Phytotoxic Activity of Origanum heracleoticum and O. majorana Essential Oils Growing in Cilento (Southern Italy).

There is a growing interest in a potential use of essential oils (EOs) as a replacement for traditional pesticides and herbicides. The aims of this study were to: (i) Identify the chemical composition of the two EOs derived from Origanum heracleoticum L. and O. majorana L., (ii) evaluate the in vitro antifungal activity of the EOs against some postharvest phytopathogens (Botrytis cinerea, Penicillium expansum, Aspergillus niger and Monilinia fructicola), (iii) evaluate the in vitro antibacterial activity against Bacillus megaterium, Clavibacter michiganensis, Xanthomonas campestris, Pseudomonas fluorescens and P. syringae pv. phaseolicola, (iv) evaluate the effect of both studied EOs on the spore germination percentage and their minimum inhibitory concentration (MIC) against M. fructicola, and (v) study the possible phytotoxicity of the two EOs and their major constituents, carvacrol for O. heracleoticum and terpinen-4-ol for O. majorana, against tha germination and initial radicle growth of radish, lettuce, garden cress and tomato. The two EOs demonstrated promising in vitro antimicrobial and antifungal activities against all tested microorganisms. EOs showed high inhibition of spore germination percentage at the minimal inhibitory concentration of 500 and 2000 µg/mL, respectively. Moreover, both germination and radical elongation of selected plant species were sensitive to the oils.

Effect of reclamation treatments on microbial activity and phytotoxicity of soil degraded by the sulphur mining industry.

The aim of the work was to determine the trend, intensity and changes of selected microbial and phytotoxic parameters of degraded soil in the area of former sulphur mine reclaimed by post-flotation lime (PFL), sewage sludge (SS), mineral wool (MW- mixed with soil, MWP-pad) and mineral fertilizer (NPK). The following parameters: number of proteolytic bacteria and fungi, ammonification, nitrification, activities of alkaline phosphatase and arylsulphatase Lepidium sativum growth index (GI) and phenolic compounds were analysed in the soil in second and third year of the experiment. The addition of the SS separately or in combination with other remediation agents was found to be the most valuable for the number of microorganisms, intensification of nitrification process and enzymatic activities. In objects where other materials were added without sewage sludge, the inhibition of fungal growth as well as alkaline phosphatase and arylsulphatase activities was observed, however the inhibitory effect declined with time. The observed increase of GI shows the long-term, positive effect of treatments on soil properties concerning plant growth. The use of lime and lime together with sewage sludge contributed to the decrease in the content of phenolic compounds in the reclaimed soil.

Glucopyranosylidene-spiro-benzo[ b][1,4]oxazinones and -benzo[ b][1,4]thiazinones: Synthesis and Investigation of Their Effects on Glycogen Phosphorylase and Plant Growth Inhibition.

Glucopyranosylidene-spiro-benzo[ b][1,4]oxazinones were obtained via the corresponding 2-nitrophenyl glycosides obtained by two methods: (a) AgOTf-promoted glycosylation of 2-nitrophenol derivatives by O-perbenzoylated methyl (α-d-gluculopyranosyl bromide)heptonate or (b) Mitsunobu-type reactions of O-perbenzoylated methyl (α-d-gluculopyranose)heptonate with bulky 2-nitrophenols in the presence of diethyl azodicarboxylate (DEAD) and PPh3. Catalytic hydrogenation (H2-Pd/C) or partial reduction (e.g., H2-Pd/C, pyridine) of the 2-nitro groups led to spiro-benzo[ b][1,4]oxazinones and spiro-benzo[ b][1,4]-4-hydroxyoxazinones by spontaneous ring closure of the intermediate 2-aminophenyl or 2-hydroxylamino glycosides, respectively. The analogous 2-aminophenyl thioglycosides, prepared by reactions of O-perbenzoylated methyl (α-d-gluculopyranosyl bromide)heptonate with 2-aminothiophenols, were cyclized in m-xylene at reflux temperature to the corresponding spiro-benzo[ b][1,4]thiazinones. O-Debenzoylation was effected by Zemplén transesterification in both series. Spiro-configurations were determined by NMR and electronic circular dichroism time-dependent density functional theory (ECD-TDDFT) methods. Inhibition assays with rabbit muscle glycogen phosphorylase b showed (1' R)-spiro{1',5'-anhydro-d-glucitol-1',2-benzo[ b][1,4]oxazin-3(4 H)-one} and (1' R)-spiro{1',5'-anhydro-d-glucitol-1',2-benzo[ b][1,4]thiazin-3(4 H)-one} to be the most efficient inhibitors (27 and 28% inhibition at 625 µM, respectively). Plant growth tests with white mustard and garden cress indicated no effect except for (1' R)-4-hydroxyspiro{1',5'-anhydro-d-glucitol-1',2-benzo[ b][1,4]oxazin-3(4 H)-one} with the latter plant to show modest inhibition of germination (95% relative to control).

Monochromatic lights-induced trends in antioxidant and antidiabetic polyphenol accumulation in in vitro callus cultures of Lepidium sativum L.

Lepidium sativum L. is an important edible, herbaceous plant with huge medicinal value as cardio-protective, hepatoprotective and antitumor agent. This study was designed and performed to investigate biosynthesis of plant's active ingredients in callus cultures of L. sativum in response to the exposure of multi spectral lights. Optimum biomass accumulation (15.36 g/L DW), total phenolic and flavonoid contents (TPC; 47.43 mg/g; TFC; 9.41 mg/g) were recorded in calli placed under white light (24 h) compared to rest of the treatments. Antioxidant enzymatic activities i.e. superoxide dismutase and peroxidase were found optimum in cultures exposed to green light (SOD; 0.054 nM/min/mg FW, POD; 0.501 nM/min/mg FW). Phytochemical analysis further confirmed the potential influence of white light exposure on enhanced production of plant's metabolites. Significant enhancement level of major metabolic compounds such as chlorogenic acid (7.20 mg/g DW), quercetin (22.08 mg/g DW), kaempferol (7.77 mg/g DW) and minor compounds including ferulic acid, sinapic acid, protocatechuic acid, vanillic acid and caffeic acid were recorded in white light compared to control (photoperiod), whereas blue light increased the p-coumaric acid accumulation. Moreover, callus cultures of this plant under white light (24 h) showed highest in vitro based anti-diabetic and antioxidant activities compared to other conditions. Finding of our current study revealed that multi spectral lights are proved to be an effective strategy for enhancing metabolic quantity of antioxidant and anti-diabetic bioactive compounds in callus cultures of L. sativum L.

Biochars from olive mill waste have contrasting effects on plants, fungi and phytoparasitic nematodes.

Olive mill waste (OMW), a byproduct from the extraction of olive oil, causes serious environmental problems for its disposal, and extensive efforts have been made to find cost-effective solutions for its management. Biochars produced from OMW were applied as soil amendment and found in many cases to successfully increase plant productivity and suppress diseases. This work aims to characterize biochars obtained by pyrolysis of OMW at 300 °C to 1000 °C using 13C NMR spectroscopy, LC-ESI-Q-TOF-MS and SEM (Scanning Electron Microscopy). Chemical characterization revealed that biochar composition varied according to the increase of pyrolysis temperature (PT). Thermal treated materials showed a progressive reduction of alkyl C fractions coupled to the enrichment in aromatic C products. In addition, numerous compounds present in the organic feedstock (fatty acids, phenolic compounds, triterpene acids) reduced (PT = 300 °C) or completely disappeared (PT ≥ 500 °C) in biochars as compared to untreated OMW. PT also affected surface morphology of biochars by increasing porosity and heterogeneity of pore size. The effects of biochars extracts on the growth of different organisms (two plants, one nematode and four fungal species) were also evaluated. When tested on different living organisms, biochars and OMW showed opposite effects. The root growth of Lepidium sativum and Brassica rapa, as well as the survival of the nematode Meloidogyne incognita, were inhibited by the untreated material or biochar produced at 300 °C, but toxicity decreased at higher PTs. Conversely, growth of Aspergillus, Fusarium, Rhizoctonia and Trichoderma fungi was stimulated by organic feedstock, while being inhibited by thermally treated biochars. Our findings showed a pattern of association between specific biochar chemical traits and its biological effects that, once mechanistically explained and tested in field conditions, may lead to effective applications in agriculture.

Changes in Phenolic Compounds and Phytotoxicity of the Spanish-Style Green Olive Processing Wastewaters by Aspergillus niger B60.

This study systematically investigated the degradation kinetics and changes in the composition of phenolic compounds in Spanish-style Chalkidiki green olive processing wastewaters (TOPWs) during treatment using Aspergillus niger B60. The fungal growth and phenol degradation kinetics were described sufficiently by the Logistic and Edward models, respectively. The maximum specific growth rate (2.626 1/d) and the maximum degradation rate (0.690 1/h) were observed at 1500 mg/L of total polar phenols, indicating the applicability of the process in TOPWs with a high concentration of phenolic compounds. Hydroxytyrosol and the other simple phenols were depleted after 3-8 days. The newly formed secoiridoid derivatives identified by HPLC-DAD-FLD and LC-MS are likely produced by oleoside and oleuropein aglycon via the action of fungal ß-glucosidase and esterase. The treated streams were found to be less phytotoxic with reduced chemical oxygen demand by up to 76%. Findings will provide useful information for the subsequent treatment of residual contaminants.

Plant assays and avoidance tests with collembola and earthworms demonstrate rehabilitation success in bauxite residue.

Bauxite residues are a by-product of alumina manufacture from bauxite ore and are commonly disposed of in purpose-built bauxite residue disposal areas (BRDAs). Revegetation is viewed as the most effective way to landscape and rehabilitate closed BRDAS and physicochemical assessment remains the primary indicator of rehabilitation success. Little is known about the ability of keystone mesofaunal species to colonise and establish in these environments yet the long-term success of rehabilitation is dependent on residues becoming suitable habitats for such groups. Using six different residue treatments (untreated, leached, organic application, organic amended, and two revegetated field treatments) together with OECD test soil, this study assessed the characteristics of residues with plant germination and seedling development using the Rhizotest™ approach with Lepidium sativum, Sinapis alba, and Sorghum bicolor. Avoidance tests with soil mesofauna Eisenia foetida together with growth and reproduction tests for Folsomia candida were conducted to determine possibility of inhibition in residue soils. Unamended residue is inhibitory to plant growth and mesofaunal establishment. Amendment improves the physicochemical properties of the residue, and data revealed that both gypsum and organic addition is required to promote conditions favourable to plant growth and mesofauna establishment. Earthworms avoid residues with elevated Na content but will choose substrate with high soluble Ca content. F. candida preferentially moves to residues from field treatments, and both mortality and reproduction rates are comparable or superior to OECD soil. On the basis of these assays, we propose that bauxite residue can be transformed to a soil-like medium capable of supporting keystone species.

Phytotoxicity assessment of olive mill solid wastes and the influence of phenolic compounds.

The main objective of this work is to evaluate the phytotoxicity of olive mill solid wastes (OMW) produced in two different centrifugation technologies and also the toxicity associated with specific phenolic compounds. Two samples of waste were collected in two-phase (2P-OMW) and three-phase (3P-OMW) centrifugation olive oil production processes, and cress bioassays with Lepidium sativum L. were employed to evaluate phytotoxicity. Although both OMW have similar total phenolic content (TPh), results confirmed that 2P-OMW is more phytotoxic than 3P-OMW. When extracts from 2P-OMW at liquid to solid ratio of 10 L kg-1 were applied none of the seeds germinated, i.e. germination index (GI) was 0%, while for 3P-OMW GI was 94.3%. Growth tests in soil and mixtures with OMW also led to more favorable results for 3P-OMW, whereas worse results than those obtained in the control experiments were observed. In order to discriminate the individual influence of eleven phenolic compounds, gallic acid, protocatechuic acid, cinnamic acid, syringic acid, 3,4,5-trimethoxybenzoic acid, 4-hydroxybenzoic acid, vanillic acid, p-coumaric acid, caffeic acid, veratric acid and phenol were tested in the concentration range of 5-500 mg L-1. Results showed that cinnamic acid is the most phytotoxic, with EC50 of 60 mg L-1, which is related with its hydrophobicity. Moreover, increasing -OH and -OCH3 groups in these molecules seem to reduce phytotoxicity. Tests with a mixture of six phenolic compounds demonstrated there are neither synergistic nor additive effects. The phytotoxicity appears to be determined by the presence of the most lipophilic phenolic molecule.

Effect of addition of sewage sludge and coal sludge on bioavailability of selected metals in the waste from the zinc and lead industry.

This study evaluated the content of bioavailable forms of selected heavy metals present in the waste from Zn and Pb processing that can potentially have an effect on the observed difficulties in reclamation of landfills with this waste. The particular focus of the study was on iron because its potential excess or deficiency may be one of the causes of the failure in biological reclamation. The study confirmed that despite high content of total iron in waste (mean value of 200.975gkg-1), this metal is present in the forms not available to plants (mean: 0.00009gkg-1). The study attempted to increase its potential bioavailability through preparation of the mixtures of this waste with additions in the form of sewage sludge and coal sludge in different proportions. Combination of waste with 10% of coal sludge and sewage sludge using the contents of 10%, 20% and 30% increased the amounts of bioavailable iron forms to the level defined as sufficient for adequate plant growth. The Lepidum sativum test was used to evaluate phytotoxicity of waste and the mixtures prepared based on this waste. The results did not show unambiguously that the presence of heavy metals in the waste had a negative effect on the growth of test plant roots.

Emerging Concern from Short-Term Textile Leaching: A Preliminary Ecotoxicological Survey.

Textile dyes and their residues gained growing attention worldwide. Textile industry is a strong water consumer potentially releasing xenobiotics from washing and rinsing procedures during finishing processes. On a decentralised basis, also final consumers generate textile waste streams. Thus, a procedure simulating home washing with tap water screened cotton textiles leachates (n = 28) considering physico-chemical (COD, BOD5, and UV absorbance) and ecotoxicological data (Daphnia magna, Pseudokirchneriella subcapitata and Lepidium sativum). Results evidenced that: (i) leachates presented low biodegradability levels; (ii) toxicity in more than half leachates presented slight acute or acute effects; (iii) the remaining leachates presented "no effect" suggesting the use of green dyes/additives, and/or well established finishing processes; (iv) no specific correlations were found between traditional physico-chemical and ecotoxicological data. Further investigations will be necessary to identify textile residues, and their potential interactions with simulated human sweat in order to evidence potential adverse effects on human health.