Elisabetta Loffredo

Removal of bisphenol A by the freshwater green alga Monoraphidium braunii and the role of natural organic matter.

Phytoremediation of waters by aquatic organisms such as algae has been recently explored for the removal of organic pollutants possessing endocrine disrupting capacity. Monoraphidium braunii, a green alga known for rapid growth and good tolerance to different natural organic matter (NOM) qualities, was tested in this study for the ability to tolerate and remove the endocrine disruptor bisphenol A at concentrations of 2, 4 and 10mgL(-1), either in NOM-free or NOM-containing media. NOM at concentrations of 2, 5 and 20mgL(-1) of DOC, was added because it may interfere with xenobiotics and modify their effects, modulate algal growth performances or produce a trade-off of both effects. After 2 and 4 days of algal growth, the cell number and size, the maximum quantum yield of photosystem II in the dark or light adapted state, and the chlorophyll a content were recorded in order to evaluate the algal response to bisphenol A. Moreover, the residual bisphenol A was measured in the algal cultures by chromatographic technique. Results indicated that after 2 and 4 days bisphenol A at the lower concentrations was not toxic for alga, whereas at the highest concentration it reduced algal growth and photosynthetic efficiency. The sole NOM and its combinations with bisphenol A at the lower concentrations increased the cell number and the chlorophyll a content of algae. After 4-day growth, good removal efficiency was exerted by M. braunii at concentrations of 2, 4 and 10mgL(-1) removing, respectively, 39%, 48% and 35% of the initial bisphenol A. Lower removal percentages were found after 2-day growth in the different treatments. NOM at any concentration scarcely influenced the bisphenol A removal. On the basis of data obtained, the use of M. braunii could be reasonably recommended for the phytoremediation of aquatic environments from bisphenol A.

Fate of anthropogenic organic pollutants in soils with emphasis on adsorption/desorption processes of endocrine disruptor compounds

After providing a brief overview of the various phenomena that anthropogenic organic pollutants (AOPs) of various nature and origin are subjected to in soil, the paper focuses on an important class of these, the endocrine disruptor compounds (EDCs), which are hormone-like substances able to alter (i.e.) disrupt, the normal endocrine functions in animals and humans. EDCs may enter the soil through current agricultural practices andor disposal of urban and industrial effluents, sludges, and wastes. The estrogenic risk of EDCs is generally related to their distribution and speciation in the various soil phases, in which adsorption/desorption processes play a very important role. Adsorption kinetics and adsorption/desorption isotherms of the EDCs: bisphenol A (BPA), octylphenol (OP), 17-α-ethynilestradiol (EED), and 17-β-estradiol (17ED), onto four samples collected from the surface (depth 0-30 cm) and deep (depth 30-90 cm) horizons of two acidic sandy soils in Portugal (P) and Germany (G) (P30 and G30, and P90 and G90, respectively) were determined using a batch equilibrium method and the high-performance liquid chromatography (HPLC) technique. Adsorption of EDCs onto all soils examined occurs in two phases, a rapid one in less than 10 h of contact, and corresponding to more than 90 % of total adsorption, and a slow one that may need several hours until attainment of equilibrium. Experimental adsorption data fit best in a linear isotherm for BPA, in a nonlinear, L-shaped Freundlich isotherm for EED, in either a linear or a nonlinear Freundlich isotherm for OP, and in a Langmuir isotherm for 17ED. Thus, no limiting adsorption is observed for soils examined over the concentration range tested for BPA, OP, and EED, whereas a maximum adsorption (i.e., saturation) is reached only by 17ED. In general, the values of the Freundlich constant, K, and of the distribution coefficient, Kd, calculated from the experimental isotherms of the four EDCs onto soils examined follow the same trend, that is: G30 > P30 > P90 > G90. Further, the K and Kd values of any EDC are positively correlated with the soil organic carbon (OC) content, which is larger for surface horizon soils than deep horizon soils. Adsorption of BPA is generally reversible, and its desorption occurs quickly and completely, thus, it is expected to move down the soil profile, and possibly contaminate the groundwater. On the contrary, OP and EED are adsorbed almost irreversibly, and are slowly and only limitedly desorbed, thus are expected to accumulate, especially in the top soil layer, and cause soil contamination.

The role of humic fractions from soil and compost in controlling the growth in vitro of phytopathogenic and antagonistic soil-borne fungi☆

The regulation capacity of four humic substance (HS) samples, a soil humic acid (HA) and two HAs and one fulvic acid (FA) isolated from a composting substrate, was evaluated at two concentrations on the growth in vitro of one plant pathogenic, Sclerotinia sclerotiorum, and two antagonistic, Trichoderma viride and T. harzianum, soil-borne fungi. The presence of any HS sample in the growing medium, especially those from the composting substrate, caused a relevant inhibition of the mycelial growth of S. sclerotiorum and a marked stimulation of sclerotial formation that was exhibited as early appearance and numerical increase. On the contrary, the same HS treatments generally did not inhibit the growth of the two Trichoderma species. In particular, T. viride was significantly stimulated by any HS sample at any concentration, with the only exception of HA from fresh-composting substrate, whereas T. harzianum appeared to be stimulated only slightly or not significantly influenced. Only S. sclerotiorum showed evident high correlations of both the extent of the inhibitory action on mycelial growth and the final number of sclerotia with some chemical and functional properties of HS, such as total acidity, COOH group content, and elemental composition.

Potential of various herbaceous species to remove the endocrine disruptor bisphenol A from aqueous media.

Several different plants are capable of removing and detoxifying the endocrine disruptor bisphenol A from water starting with initial concentrations of 4.6 mg L(-1) and 46 mg L(-1). Bisphenol A seems to be glycosylated, transformed to polar compounds, and bound as residue by five forage grasses, fescue, couch grass, perennial ryegrass, Siberian wheatgrass, and white clover, and three horticultural species, cucumber, marrow plant, and radish. Septic and axenic testing established that microbial degradation is possible for fescue and radish, and perennial ryegrass exudates seemed to contain enzymatic activity that transforms bisphenol A, but this activity is evidently deactivated by microorganisms. Although the grasses tested were more effective than the horticultural species, the optimal species of plants best suited for phytoremediation of bisphenol A was not determined. The limited plant testing during 16d does not define how nor which phytoremediation practices can be applied, but the removal efficiency and evident transformation of bisphenol A justify further feasibility, pilot, and treatability testing of different wastewaters.

THE ROLE OF HUMIC SUBSTANCES IN THE FATE OF ANTHROPOGENIC ORGANIC POLLUTANTS IN SOIL WITH EMPHASIS ON ENDOCRINE DISRUPTOR COMPOUNDS

In the first part of this paper an overview is provided of the various phenomena that anthropogenic organic pollutants (AOPs) of various nature and origin are subjected in soil and of the specific role exerted by soil humic substances (HS) in these processes. The paper then focuses on adsorption/desorption of an important class of organic pollutants, i.e., endocrine disruptor compounds (EDCs), onto soil humic acids (HAs) that are the most abundant and chemically and biochemically active fractions of HS and soil organic matter. EDCs are hormone-like substances that include natural and synthetic estrogens and several pesticides, industrial chemicals, and plastic and pharmaceutical products and byproducts which are able to alter, i.e., disrupt, the normal endocrine functions in animals and humans. These compounds may enter the soil through current agricultural practices and /or disposal of urban and industrial effluents, sludges and wastes. The estrogenic risk of EDCs is generally related to their distribution and speciation in the various soil phases, in which adsorption/desorption processes play a very important role. Adsorption kinetics and adsorption/desorption isotherms of the EDCs bisphenol A (BPA), octylphenol (OP), 17-alpha-ethynyl estradiol (EED) and 17-beta-estradiol (17ED) onto HA samples isolated from the surface (0-30 cm) and deep (30-90 cm) horizons of two sandy soils were determined using a batch equilibrium method and the HPLC technique. Adsorption of EDCs onto HAs occurs in two phases, a rapid one in the first few hours of contact, which corresponds to more than 90% of total adsorption, and a slow one that needs generally less than 24 h to be completed. Experimental adsorption data were best fitted in a Langmuir isotherm for BPA and 17ED, in a linear isotherm for OP and in a nonlinear, L-shaped Freundlich isotherm for EED. Thus, no limiting adsorption is observed for EED and OP

In vitro assessment of the inhibition of humic substances on the growth of two strains of Fusarium oxysporum

The effects of four humic substance (HS) samples, a soil humic acid and two humic acids and one fulvic acid isolated from a composting substrate, were evaluated on the mycelial growth of Fusarium oxysporum f. sp. melonis (FOM) and F. oxysporum f. sp. lycopersici (FOL). In general, any HS treatment reduced significantly the radial growth of the FOM mycelium either in normal [potato dextrose agar (PDA) medium] or sub-optimal (water–agar medium) nutritional conditions. Differently, the FOL growth, which was tested only on PDA, was either inhibited or stimulated on dependence of the HS treatment used. The HS fractions isolated from the composting substrate were the most effective inhibitors of mycelial growth of both fungi. Furthermore, any HS treatment was also able to alter the germination process of FOL in aqueous medium, not only by reducing significantly the number of viable germinating conidia but also by generally decreasing the rate of conidial germ-tube elongation. Apparently, the extent of the inhibitory action was related to some chemical and functional properties of HS, such as the COOH group content and elemental composition.

Biodecontamination of water from bisphenol A using ligninolytic fungi and the modulation role of humic acids

Bisphenol A (BPA) is an endocrine disruptor compound (EDC) of xenobiotic origin occurring in natural waters and wastewaters, especially in the most industrialized and urbanized areas. Recent investigations report the use of ligninolytic fungi for the removal of aromatic contaminants, including some EDCs, from different matrices. Humic acids (HA) are widely spread in all natural systems and their presence is ascertained to interfere with microbial growth and activity. The objective of this study was to assess the capacity of three ligninolytic fungi, Trametes versicolor, Stereum hirsutum and Pleurotus ostreatus, to remove BPA at the concentration of 4.6 mg L(-1) from water. Fungal growth on potato dextrose agar (PDA), in the absence and in the presence of a leonardite HA or a green compost HA, was evaluated during the biodecontamination process. The methodological approach adopted in this study excluded the presence of the mycelium in the contaminated water. Results obtained evidenced a relevant removal of BPA by any fungus when PDA only was used as growing medium. The addition of leonardite HA and compost HA stimulated the mycelial growth of any fungus, especially T. versicolor, and significantly enhanced the removal of the contaminant from water by, respectively, T. versicolor only and T. versicolor and S. hirsutum.

Evaluation of antimutagenic and desmutagenic effects of humic and fulvic acids on root tips of Vicia faba

Humic acids (HA) and fulvic acids (FA) of different origin were evaluated for their antimutagenic and/or desmutagenic activity on Vicia faba germinating seeds treated with the mutagen compound maleic hydrazide (MH). Both HA and FA were tested at two different concentrations, 20 and 200 mg L−1, either alone or together with 10 mg L−1 of MH. Two experimental procedures were used to investigate the occurrence and nature of the antimutagenic or desmutagenic activity. In procedure 1, HA or FA and MH were interacted for 24 h and then added to the seeds. In procedure 2, the seeds were first treated with HA or FA for 6 days and then transferred to plates containing the MH solution, so that no interaction occurred between HA or FA and MH outside the seeds. The evaluation of the genotoxic activity was done by counting both micronuclei and aberrant anatelophases in root tip cells. Results obtained by using procedure 1 showed a clear desmutagenic action of HA and FA used at both concentrations, whereas results of procedure 2 indicated no antimutagenic effect of HA or FA. © 2000 John Wiley & Sons, Inc. Environ Toxicol 15: 513–517, 2000

Adsorption of chlordane onto humic acids from soils and pig slurry

Adsorption of trans- and cis-chlordane onto humic acids (HAs) isolated from soils and a pig slurry was measured using a batch equilibrium method followed by gas chromatographic analysis. Experimental data for adsorption of either chlordane isomers onto any HA examined were best fitted by a Langmuir-type isotherm. The adsorption capacity of pig slurry HA for chlordane was slightly lower than that of soil HAs. FT-IR, fluorescence and ESR spectroscopic data excluded the formation of strong chemical bonds between chlordane and HA, thus suggesting that chlordane can be adsorbed to HA only by physical (hydrophobic) mechanisms, involving to some extent fluorophore groups of the HAs.

Triallate adsorption onto humic acids of different origin and nature

Humic acids (HAs) isolated from two different soils sampled at two different depths and from a pig slurry used as soil amendment, and their interaction products with the herbicide triallate were characterized by elemental and functional group analyses and Fourier transform infrared (FT-IR), electron spin resonance (ESR) and fluorescence spectroscopy in the emission, excitation and synchronous scan modes. The pig slurry HA exhibited a greater aliphatic character, higher presence of proteinaceous and polysaccharide constituents, lower acidic functional group content, and lower aromatic polycondensation and humification degrees than soil HAs. Only small differences occurred between HAs from the two soil types and the two sampling depths of each soil. Adsorption of triallate onto HAs, measured using a slurry-type method combined with high-pressure liquid chromatography (HPLC), could be described in all cases by linear isotherms. The extent of adsorption of triallate onto pig slurry HA was between two and four orders of magnitude higher than that onto soil HAs. The types of binding mechanisms appeared to be related to the compositional, structural and functional properties of the HA. Hydrophobic bonds possibly prevailed in the interaction of triallate with pig slurry HA, whereas adsorption of triallate onto soil HAs possibly involved charge-transfer and ionic bonds, with the participation of fluorophore groups of the HA macromolecules.