1,721,006 research outputs found
Recent Advances on Innovative Materials from Biowaste Recycling for the Removal of Environmental Estrogens from Water and Soil
Full text linkNew technologies have been developed around the world to tackle current emergencies such as biowaste recycling, renewable energy production and reduction of environmental pollution. The thermochemical and biological conversions of waste biomass for bioenergy production release solid coproducts and byproducts, namely biochar (BC), hydrochar (HC) and digestate (DG), which can have important environmental and agricultural applications. Due to their physicochemical properties, these carbon-rich materials can behave as biosorbents of contaminants and be used for both wastewater treatment and soil remediation, representing a valid alternative to more expensive products and sophisticated strategies. The alkylphenols bisphenol A, octylphenol and nonylphenol possess estrogenic activity comparable to that of the human steroid hormones estrone, 17β-estradiol (and synthetic analog 17α-ethinyl estradiol) and estriol. Their ubiquitous presence in ecosystems poses a serious threat to wildlife and humans. Conventional wastewater treatment plants often fail to remove environmental estrogens (EEs). This review aims to focus attention on the urgent need to limit the presence of EEs in the environment through a modern and sustainable approach based on the use of recycled biowaste. Materials such as BC, HC and DG, the last being examined here for the first time as a biosorbent, appear appropriate for the removal of EEs both for their negligible cost and continuously improving performance and because their production contributes to solving other emergencies, such as virtuous management of organic waste, carbon sequestration, bioenergy production and implementation of the circular economy. Characterization of biosorbents, qualitative and quantitative aspects of the adsorption/desorption process and data modeling are examined
The chemistry of soil organic matter
No full textSoil organic matter (SOM) is one of the most important natural resources and the basis of soil fertility. The term SOM generally refers to the total organic carbon (C)-containing substances in soil. The total mass of organic C in soils has been estimated at 22 × 10 14 kg, similar to the total of all other C reservoirs on the earth’s surface (21 × 10 14 kg). 1 SOM contents range from less than 1% in sandy and desert soils to 1%-5% (w/w) in the surface horizons (top 15 cm) of typical mineral and agricultural soils, to almost 100% in organic soils. 2 Even at the lowest levels, the role of SOM in all processes occurring in soil is ascertained to be highly relevant
Wood biochars and vermicomposts from digestate modulate the extent of adsorption-desorption of the fungicide metalaxyl-m in a silty soil
No full textThis study aimed to investigate changes in metalaxyl-M sorption-desorption capacity of soil following the addition of two types of amendments. Two biochars (BC) from grapevine pruning residues (BC-G) and spruce wood (BC-S) and two vermicomposts (VC) obtained vermicomposting digestates from a mixture of manure and olive mill wastewater (VC-M) and buffalo manure (VC-B) were used. Using a batch equilibration method, the materials and a silt loam soil non-amended or amended with each material at 2% (w/w) were interacted with the fungicide at a concentration of 2 mg L−1 for kinetics study and in the range 1–20 mg L−1 for sorption isotherms. Kinetics results showed that metalaxyl-M onto the amendments and non-amended soil followed preferentially a pseudo-second-order model, thus indicating a chemisorption process. Sorption isotherm data of the product on BC and VC fitted well the Freundlich equation, whereas those on non-amended and amended soil followed preferentially a linear model. The KFads values were 995.2, 788.5, 55.2, 52.1, 6.4, 6.0, 3.4, 2.6 and 1.5 L kg−1 for BC-G, BC-S, VC-M, VC-B, soil-BC-G, soil-BC-S, soil-VC-M, soil-VC-B and non-amended soil, respectively. Product desorption from each soil sample occurred to a lesser extent than sorption. Highly significant correlations (P < 0.005) were found between the values of sorption and desorption constants of all adsorbents and organic C content, thus confirming the prominent role of organic matter in the sorption process of metalaxyl-M
Adsorptive removal of ascertained and suspected endocrine disruptors from aqueous solution using plant-derived materials
No full textThe present study deals with the use of low-cost plant-derived materials, namely a biochar, spent coffee grounds, spent tea leaves, and a compost humic acid, for the adsorptive removal from water of two estrogens, 4-tert-octylphenol (OP) and 17-β-estradiol (E2), and two pesticides, carbaryl and fenuron, each spiked at a concentration of 1 mg L−1. Kinetics and adsorption isotherms have been performed using a batch equilibrium method to measure the sorption capacities of the adsorbents towards the four molecules. Adsorption constants were calculated using the linear, Freundlich, and Langmuir models. Kinetics data obtained evidenced a rapid adsorption of each compound onto both biochar and coffee grounds with the attainment of a steady-state equilibrium in less than 4 h. Significant differences among the adsorbents and the compounds were found regarding the model and the extent of adsorption. In general, the estrogens were adsorbed more quickly and in greater amounts than the less hydrophobic pesticides, following the order: OP > E2 > carbaryl > fenuron. The ranges of Freundlich constants obtained for OP, E2, carbaryl, and fenuron onto the sorbents were 5049–2253, 3385–206, 2491–79, and 822–24 L kg−1, respectively. The maximum values of constants were obtained for biochar, except for OP that was more adsorbed by spent coffee grounds. Adsorption kinetic data followed a pseudo-second-order model, thus indicating the occurrence of chemical interactions between the compounds and the substrates. The remarkable sorption capacities of all adsorbents towards the four molecules suggest the valuable exploitation of these materials for decontamination purposes, such as the treatment of wastewater before a feasible recycle in soil
Soil Amendment with Biochar, Hydrochar and Compost Mitigates the Accumulation of Emerging Pollutants in Rocket Salad Plants
Full text linkThe uptake of organic pollutants by agricultural plants and their accumulation in edible parts cause serious health problems to animals and humans. In this study, we used carbon-rich materials, such as biochar (BC), hydrochar (HC), and green compost (GC), to reduce the absorption and accumulation of three pesticides, imidacloprid (IMI), boscalid (BOS), and metribuzin (MET) and two endocrine disruptors, 4-tert-octylphenol (OP) and bisphenol A (BPA), in rocket salad plants (Eruca vesicaria L.). After an experimental period of 35 days, compared to unamended soil, the addition of BC, HC, and GC significantly reduced chemical phytotoxicity, increasing the elongation of the aerial plant parts by 26, 25, and 39%, respectively, whereas GC increased the fresh biomass by 21%. The assessment of residual chemicals in both soil and plant tissues indicated that any amendment was very effective in enhancing the retention of all compounds in soil, thus reducing their uptake by plants. Averagely for the five compounds, the reduction of plant absorption followed the trend BC > HC > GC. In particular, the presence of BC decreased the chemical residues in the plants from a minimum of 71% (IMI) to a maximum of 91% (OP). The overall results obtained encourage the incorporation in soil of C-rich materials, especially BC, to protect leafy food plants from the absorption and toxicity of organic pollutants of a wide range of hydrophobicity, with relevant benefits for consumers
Aquatic humic substances inhibit clastogenic events in germinating seeds of herbaceous plants
No full textOne humic acid (HA) and two fulvic acids (FAs) of aquatic origin have been tested for their capacity to inhibit clastogenic events caused by maleic hydrazide (MH) in germinating seeds of the herbaceous plant species Allium cepa and Vicia faba. Either HA or FA at concentrations of 50 and 500 mg L-1 was interacted with 10 mg L-1 MH for 24 h before addition to the seeds. The evaluation of genotoxic activity was made by counting micronuclei (MN) and aberrant anatelophases (AT) in root tip cells after treatment with HA or FA alone, MH alone, and interacted HA + MH and FA + MH. Regular AT were also counted as an index of mitotic activity. In all cases HA and FA nteracted with MH showed an evident anticlastogenic action indicated by the marked reduction of genetic anomalies. In A. cepa, the anticlastogenic effect of HA and FA was more significant for aberrant AT than for MN, whereas the opposite was true in the case of V. faba. The protective effect exhibited for both anomalies by HA was slightly higher than that of the corresponding FA in A. cepa, whereas no significant differences between these HA and FA treatments were observed in the case of V. faba. The two FAs generally showed similar anticlastogenic behaviors with slight quantitative differences observed as a function of the type of anomaly and the plant species. The effects of HA and FA concentration differed depending on the type of anomaly observed, the plant species, and FA origin. In V. faba, cell division, that is, the number of regular AT, was generally depressed by HA and FA at either concentration with respect to the control. In A. cepa, HA and FA produced either stimulating or inhibiting effects on regular AT depending on their nature, origin, and concentration
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
- …
