1,720,980 research outputs found
Phytodecontamination of water systems from phenolic endocrine disruptors and the regulation role of natural organic matter
Full text linkIn the last decades an increasing number of natural and synthetic compounds have been recognized as endocrine disruptors (EDs) because of their hormone-like activity and capacity to alter the normal hormonal functions of animals and humans. Among EDs, there are phenolic compounds widely present in terrestrial and aquatic systems, such as bisphenol A, 4-nonylphenol (NP), 4- tert-octylphenol, estrone, ethynilestradiol and so on. Estrogenic effects of these molecules have been ascertained on mollusks, crustaceans, fishes, amphibians and mammals starting from concentrations of 1 μgL−1. Thus, the removal of EDs from polluted media is a priority goal in order to avoid risks for the ecosystem health. Nowadays, several physico-chemical methods are mainly used for the removal of EDs from liquid and solid matrices. Nevertheless, these methods are expensive, difficult to apply and may produce a negative impact on the environment. Recently, most of studies on soil and water remediation from EDs address more sustainable techniques using bacteria, fungi, microbial enzymes and plants. Phytoremediation uses photoautotrophic organisms to uptake, transform, volatilize or stabilize pollutants present in waters, sediments, soils and atmosphere. As this technology is solar driven and exploits natural sources, it is consequently environmentally safe and cost-effective. A fundamental role in the phytoremediation process is played by natural organic molecules, mainly dissolved organic matter and humic substances. These compounds are ubiquitous in all terrestrial and aquatic environments and they interact at various extent with all contaminants deriving from agricultural, industrial and urban activities. Natural organic matter has a relevant biological activity and may also regulate the decontamination capacity of plants and other organisms, such as algae and fungi. In this review, some results of phytodecontamination studies conducted using herbaceous plant species which are presented and discussed. Further, the modulation role of natural organic matter on the phytodecontamination process is highlighted
Fertilization promotes microbial growth and minimum tillage increases nutrient-acquiring enzyme activities in a semiarid agro-ecosystem
Full text linkMicroorganisms respiratory and enzymatic activities provide sensitive indicators of changes in soil properties, such as those caused by interactive effects of tillage and fertilization regimes or other agricultural practices. However, the rapid, adaptive microbial growth, respiratory and enzymatic responses to changes in soil environments induced by specific agricultural practices are not well understood. Thus, to explore these adaptations we compared effects of contrasting environments on functional microbial traits (growth and enzyme kinetic parameters) in a Mediterranean agro-ecosystem. These environments differed in long-term disturbance (no, minimum, or conventional tillage), nitrogen-richness (fertilization with 90 kg N ha−1 versus no fertilization), and resource scarcity (increasing with soil depth in 0–30, 30–60 and 60–90 cm layers). Reducing soil disturbance from conventional to minimum tillage promoted microbial growth through shorter Tlag and larger active biomass fraction and induced increases in N- and P-acquiring enzyme activities by increasing nutrients limitation. Fertilization stimulated increases in fast-growing microorganisms with low substrate-affinity enzyme systems, microbial biomass, enzymatic activities, and turnover rates of soil organics. In contrast, increasing scarcity of resources with soil depth strongly reduced microbial biomass and activity. A lack of correlation between soil and enzymatic stoichiometric ratios raises concern regarding the applicability of eco-enzymatic stoichiometric indexes in Mediterranean agro-ecosystems. We conclude that decomposition and turnover of organic substrates under contrasting agricultural practices are mediated by microbial communities with distinct functional traits (active fraction, growth parameters) and enzyme properties (Vmax, Km), which need to be considered in smart land use regimes
Chemical and spectroscopic characteristics of humic acids and dissolved organic matter along two Alfisol profiles
No full textThe aim of this study was to elucidate the heterogeneous structural and functional composition of humic acids (HAs) and dissolved organic matter (DOM) isolated from two Alfisol profiles with different soil texture, in order to develop a better understanding of the organic matter dynamics. Soil samples were collected at different depths from three (Ap, 2AB and 2Bt) and eight (A1, A2, A3, E1, E2, 2Bt1, 2Bt2 and 2Bt3) soil horizons of two Alfisols located in the south (PR1) and north (PR2) of Italy, with a clay texture and a silt loam to loam ones, respectively. Chemical and spectroscopic methods were used to characterize the HAs and the DOM isolated from different soil horizons, including Ultraviolet-Visible (UV-Vis), Fourier Transform Infrared (FTIR), and Fluorescence spectroscopies. The HAs and the DOM isolated from the two Alfisols apparently showed significant differences in their compositional, structural and functional characteristics. In particular, the HAs isolated from the PR1 featured a higher degree of humification and molecular complexity with respect to those isolated from the PR2. On the contrary, the DOM samples isolated from the PR2 showed a more marked aromatic character and polycondensation degree. Both the HAs and the DOM obtained from the PR1 presented a greater qualitative homogeneity with respect to those obtained from the PR2. These results could be reasonably ascribed to the different texture and horizons of the two Alfisols, and to a greater pedogenesis occurred in the PR1. © 2014 Elsevier Ltd
Soil culturable microorganisms as affected by different soil managements in a two years wheat-faba bean rotation
Full text linkAgricultural practices greatly influence soil chemical and microbiological parameters, which affect soil fertility. The aim of this study was to investigate the effects of different tillage (conventional (CT), minimum (MT) and no tillage (NT)), fertilization (fertilization versus no fertilization), soil depth (0-30, 30-60, and 60-90 cm) and crops (wheat versus faba bean) on the abundance of selected microorganisms. Total culturable bacteria (TCB) were predominant in the microbial soil community, while total culturable yeasts (TCY) represented the minority. The TCB and total culturable fungi (TCF) were positively correlated with the content of soil organic carbon, total nitrogen and available phosphorus. The minimum tillage increased significantly the size of microbial populations, representing a good compromise between soil aeration and available nutrients as well as the faba bean. In particular, the unfertilized legume resulted in a higher TCY number with respect to the fertilized one, suggesting that somehow these microorganisms lose their low ecological competition in the presence of inorganic phosphorus. Finally, all microbial populations studied reduced their size with soil depth because of the nutrients availability, even if the TCB decreased with a far lower percentage due to the major proliferation of bacteria at the expenses of the other microbial groups
Short-term effects of different organic amendments on soil properties and organic broccoli growth and yield
No full textThe aim of this study was to evaluate the effects of different organic fertility sources on organic broccoli (Brassica oleracea var. italica) growth and yield, and on soil properties. The fertilization was designed to supply the crop with about 100 kg ha-1 of N using two amendments: a municipal solid wastes-based compost (CC), and a manure based compost (CB). The former was used alone (T1), in combination with its own water extract (CT) in fertigation (T2), and in combination to CT applied in fertigation and as foliar spray (T3). Other treatments resulted from the application of (i) CC and CB (T4); (ii) CB alone (T5); and (iii) the exhausted compost (EX) resulting from the extraction of CT (T6). Unamended plots were used as control (T7). Selected soil properties were determined at the beginning and at the end of the trial in order to estimate the effects of the various treatments on these parameters. The best yields were obtained with T4 and T5 (16.95 and
18.46 t ha-1, respectively). The application of CC alone (T1) showed slightly better growing parameters in comparison to its application in combination to CT (T2 and T3), even though the yields were not significantly different from each other. T6 showed the lowest yield of broccoli (7.03 t ha-1) among the treatments, superior only to the unfertilized control (5.38 t ha-1, T7). The different fertilizations showed a general soil enrichment of available phosphorous and organic matter, even if the latter could be only transitory. Finally, the high production costs and the low yields obtained apparently dissuade the use of compost tea and exhausted compost for the fertilization of broccoli crop
Destino dello Ptaquiloside nel sistema felce-suolo, in regime di agro-zootecnia biologica
No full textValidation of a modified QuEChERS method for the extraction of multiple classes of pharmaceuticals from soils
Full text linkBackground: The quick, easy, cheap, effective, rugged, and safe (QuEChERS) method can be employed for multi-residue analyses instead of traditional extraction methods due to its advantages in terms of extraction time and required equipment. A modified version of the QuEChERS method has been developed for quantifying eight pharmaceuticals belonging to different classes in three real soils with different chemical properties. Firstly, the soils have been polluted with all contaminants and the recoveries were determined by liquid chromatography tandem–mass spectrometry. Due to similar recoveries from the three soils, the validation of the method has been carried out only on a soil by determining linearity, recovery, precision, limit of detection (LOD) and limit of quantification (LOQ) values. A matrix-matched calibration for the soil has been adopted in order to avoid the matrix effect and three levels of fortification (50, 100 and 500 μg L−1) were used. Results: The recovery of all pharmaceuticals, with the exception of tetracycline, from any soil was between 72 and 113%. In the validation procedure, recoveries of fortified samples ranged from 80 to 99%, the relative standard deviations ranged between 1.2 and 11.8%, and the LOQ between 20 and 36.9 μg kg−1. Conclusion: The results of the present study confirmed the validity of the modified QuEChERS method for the extraction of pharmaceuticals from soils in the range 50–500 μg kg−1
Enhancement of germination and early growth of different populations of switchgrass (Panicum virgatum L.) by compost humic acids
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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