Showing papers by "Nicola Senesi published in 2006"

Molecular and Quantitative Analysis of Metal Ion Binding to Humic Acids from Sewage Sludge and Sludge-Amended Soils by Fluorescence Spectroscopy

Abstract: Humic acids (HAs) isolated from sewage sludge (SS) and control and SS-amended soils were characterized by fluorescence spectroscopy. The main feature of fluorescence spectra was a broad band with the maximum centered at excitation/emission wavelengths that were much shorter for SS-HA (340/438 nm) than for any soil HA (440/510 nm). Titration with Cu(II), Zn(II), Cd(II), and Pb(II) ions decreased fluorescence intensities of HAs. Titration data were fitted to a single-site fluorescence quenching model, and metal ion complexing capacities of each HA sample and stability constants of metal ion−HA complexes were calculated. The binding capacities of HAs and strengths of metal ion−HA complexes followed the order Pb(II) > Cu(II) > Cd(II) > Zn(II). With respect to the control soil HA, SS-HA, which showed the smallest contents of acidic functional groups and the lowest humification degree, was characterized by much smaller binding capacities and stability constants. The binding capacities and affinities of SS-amend...

Phytotoxic, clastogenic and bioaccumulation effects of the environmental endocrine disruptor bisphenol A in various crops grown hydroponically

Abstract: The effects of the endocrine disruptor bisphenol A (BPA) at concentrations of 10 and 50 mg l(-1) were evaluated on the germination and morphology, micronuclei (MN) content in root tip cells and BPA bioaccumulation of hydroponic seedlings of broad bean (Vicia faba L.), tomato (Lycopersicon esculentum Mill.), durum wheat (Triticum durum Desf.) and lettuce (Lactuca sativa L.) after 6 and 21 days of growth. In general, BPA at any dose used did not inhibit germination and early growth (6 days) of seedlings of the species examined, with the exception of primary root length of tomato which decreased at the higher BPA dose. In contrast, an evident phytotoxicity was induced by BPA in all species after 21 days of growth with evident morphological anomalies and significant reductions of the lengths and fresh and dry weights of shoots and roots of seedlings. With respect to the nutrient medium without seedlings, BPA concentration decreased markedly during the growth period in the presence of broad bean and tomato seedlings, and limitedly in the presence of durum wheat and, especially, lettuce. Further, the presence of BPA measured in roots and shoots of broad bean and tomato after 21-day growth indicated that bioaccumulation of BPA had occurred. The number of MN in broad bean and durum wheat root tip cells increased markedly by treatment with BPA at both concentrations, thus suggesting a potential clastogenic activity of BPA in these species.

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

Abstract: After providing a brief overview of the various phenomena that anthropogenic or- ganic pollutants (AOPs) of various nature and origin are subjected to in soil, the paper fo- cuses 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 gener- ally related to their distribution and speciation in the various soil phases, in which adsorp- tion/desorption processes play a very important role. Adsorption kinetics and adsorption/des- orption 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 co- efficient, K d , calculated from the experimental isotherms of the four EDCs onto soils exam- ined follow the same trend, that is: G30 > P30 > P90 ≥ G90. Further, the K and K d 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 ad- sorbed almost irreversibly, and are slowly and only limitedly desorbed, thus are expected to accumulate, especially in the top soil layer, and cause soil contamination.

Fluorescence characterization of metal ion-humic acid interactions in soils amended with composted municipal solid wastes.

Abstract: Fluorescence spectroscopy has been used to probe the structural properties and Cu(II), Zn(II), Cd(II), and Pb(II)-binding behavior of humic acid (HA)-like fractions isolated from a municipal solid waste compost (MSWC) and HAs from unamended and MSWC-amended soils. The main feature of the fluorescence spectra, in the form of emission-excitation matrix (EEM) plots, was a broad peak with the maximum centered at an excitation/emission wavelength pair that was much shorter (340/437 nm) for MSWC-HA than for unamended and MSWC-amended soil HAs (455/513 and 455/512 nm, respectively). Fluorescence intensity for MSWC-amended soil HA was less than that for unamended soil HA. These results were indicative of more aromatic ring polycondensation and humification of soil HAs, and of partial incorporation of simple and low-humified components of MSWC-HA into native soil HA, as a result of MSWC amendment. Titrations of HAs with Cu(II), Zn(II), Cd(II), and Pb(II) ions at pH 6 and ionic strength 0.1 mol L−1 resulted in a marked decrease of the fluorescence intensities of untreated HAs. By successfully fitting a single-site fluorescence-quenching model to titration data, the metal ion complexing capacities of each HA and the stability constants of metal ion-HA complexes were obtained. The binding capacities and stability constants of MSWC-HA were smaller than those of the unamended soil HA. Application of MSWC to soil slightly reduced the metal-ion-binding capacities and affinities of soil HAs.

The role of humic substances in the fate of anthropogenic organic pollutants in soil with emphasis on endocrine disruptor compounds

Abstract: 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

Humic acids reduce the genotoxicity of mitomycin C in the human lymphoblastoid cell line TK6.

Abstract: The antimutagenic/desmutagenic activity of a leonardite humic acid (LHA) and a soil humic acid (SHA) was studied in the cultured human lymphoblastoid cell line TK6 treated with mitomycin C (MMC) as reference mutagen by evaluating the induction of micronuclei (MN). Two different concentrations of HA were used, 2.5 and 10 μg/ml, in three different treatments: (1) HA alone (genotoxic test); (2) HA after 2-h pre-incubation with 0.3 μM of MMC (desmutagenic test) and (3) combinations of HA and MMC at 0.3 μM without pre-incubation (antimutagenic test). Neither of the HA used alone did produce genotoxic effects, but both HAs reduced significantly the frequencies of MN induced by MMC, especially in the desmutagenic test. A slight cell-protective effect against the cytoxicity of MMC was also exhibited by the two HAs in the desmutagenic test. The LHA showed a desmutagenic/antimutagenic activity that was more pronounced than that of SHA, which is possibly related to the higher carboxylic group content and lower phenolic group content of LHA. These results confirm the antigenotoxic action exerted by HAs in human cells, similarly to what has been previously observed in various plant species.

Humic substances and clay minerals in organically-amended semiarid soils

Abstract: Unsuitable agricultural practices have resulted in a permanent soil degradation in some semiarid areas of southeastern Spain. Because addition of exogenous organic matter has been shown to generally cause an improvement in quality of these degraded soils, the objective of this work was to evaluate the efficacy of amendment with fresh sewage sludge, composted sewage sludge, and a mixture of fresh sludge and a commercial humic substance on restoring the quality of a degraded soil 7 years after a one-time amendment with 25 kg/m organic matter. The soil used in the study was a sandy Xeric Torriorthent. Because the experimental soil plots had a slope of 15%, the effect of soil slope on these properties was also determined. Soil samples were collected from the surface layer (0-20 cm) of the hill top (shoulder) and bottom of the hill (foot slope) portions of each plot. Chemical properties, mineralogy of the clay fraction, and humic and fulvic acid contents and composition were analyzed. The exogenous organic matter was apparently incorporated into the native soil humic and fulvic acids, resulting in a significant improvement of the overall soil chemical quality. Mineral composition and amounts and structure of humic acids varied between the shoulder and foot slope portions of soil plots, suggesting an effect of soil erosion on the distribution of these substances. Organic matter amendment seemed to limit soil runoff, but more research is needed to evaluate humic substance-clay mineral interaction effects on the formation of more stable soil aggregates and on the resulting impact on soil erosion at these sites.

Spectroscopic and Thermal Investigation Of Hydrophobic and Hydrophilic Fractions Of Dissolved Organic Matter

Abstract: Hydrophobic (HO) and hydrophilic (HI) fractions of dissolved organic matter (DOM) isolated from several substrates including a source separated urban waste compost, a mechanically separated urban waste compost, an anaerobically digested municipal sewage sludge, a composted sewage sludge and a cow slurry were characterised by Fourier transform infrared spectroscopy (FT-IR), monodimensional fluorescence spectroscopy in the emission, excitation and synchronous scan modes, tridimensional excitation emission matrix (EEM) fluorescence spectroscopy, 1H nuclear magnetic resonance (1H-NMR) spectroscopy, and differential scanning calorimetry (DSC). The FT-IR spectra indicated that the HI fractions were rich in both aromatic and aliphatic structures, whereas the HO fractions were rich in carboxylic groups and polysaccharides. The synchronous scan spectra of HO fractions showed the main peak at a wavelength much longer than that of the HI fractions, which indicated a greater molecular complexity of the HO fractions w...