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Chromium in soil: environmental issues
No full textChromium (Cr) is a unique element in soil, because of (i) essentiality to human and animal life and non-essentiality for the vegetable kingdom and (ii) its possible presence in two main oxidation forms, trivalent (CrIII) and hexavalent (CrVI), which show opposite properties. The two forms have completely different effects on living organisms: the first (CrIII) is apparently useful or harmless at reasonable concentrations, while the second (CrVI) is extremely toxic. In addition, CrIII is not mobile in soil, therefore the risks of leaching are negligible, while CrVI, mainly present in the forms
of chromates (CrO2− 4 ) and dichromates (Cr2O2− 7 ), is generally mobile and often is part of crystalline minerals (ophiolites, serpentines).
Chromium-rich soils are common in many countries, where Cr minerals are diffuse and its content in natural soils (i.e. serpentine soils) may easily exceed 10,000 mg/kg.
Conversion of CrIII to CrVI has been shown in some particular soils: rich in manganese (Mn) oxides, poor in organic matter and high redox potential. On the contrary, the reverse transformation of CrVI to CrIII is very common and easier, so that it is difficult to find hexavalent chromium forms in soil solution or in leaching waters.
Chromium shows a soil-plant transfer factor (F) (“F” indicates the amount of metals that passes from the soil to the plants) very low (normally less than 5), so that Cr belongs to the less mobile elements of the soil-system. The main barrier to the income
of Cr in plants is represented by the roots. CrIII is fixed on the roots and the amount that cross the cellular wall is negligible.
The problem of Cr enrichment in soil has been often discussed not only in relation to the discharge of tannery wastes, but also to the possibility of Cr presence in soil amendments, mainly organics, and to the existence of excellent organic fertilizers produced from leather residues or wastes.
Environmental or safety issues are often cited fearing the use of such fertilizers, generally without scientific support. As a matter of fact, the United States Environmental Protection Agency has withdrawn any limit to the presence of Cr in biosolids.
The main aim of this session is to discuss updated positions of this problem, gathering the contribution of scientists who have devoted their study to chromium in recent years
Standardization and legislative regulations of commercial humic and humic-based products.
No full textHumic substances (HS) are complex, heterogeneous, mixtures of polydisperse components formed by biochemical and chemical reactions during humification processes. HS are major components of the natural organic matter in soil and water as well as in organic rich geological deposits such as lake sediments, peats, brown coals and shales. HS are involved in many processes in soils and natural waters, e.g. soil weathering, plant nutrition, pH buffering, trace metal mobility and toxicity, bioavailability, degradation and transport of hydrophobic organic chemicals, formation of disinfection by-products during water treatment, and heterotrophic production in blackwater ecosystems (web-site http://www.ihss.gatech.edu/ of the International Humic Substances Society).
In agriculture HS and HS-based products (solid and liquid) are generally used in plant nutrition: their role in increasing bioavailability of nutrients and biological activities is well supported in scientific literature (1,2). For a proper use of HS it’s fundamental to know their elemental composition as well as some basic features. This information is basically included and well described in scientific papers.
In commercial products such data are often lacking. The main reason is that at national and especially at international level (3) the specific rules neglected HS. In fact, it must be kept in mind that even the recent European Regulation 2003/2003 (3) has completely neglected organic and organic-based fertilizers and amendments. At the best the existing rules require the declaration of total content of organic and humic carbon (4). Among others, the Italian Legislative decree 217/06 (5) is one of the most advanced in Europe from this point of view.
The need of standardization and regulations of commercial humic and humic-based products is imperative in a modern agriculture and for a market globalization
Fanghi" in agricoltura, risorsa troppo spesso dimenticata
No full textSolamente pochi agricoltori potrebbero essere a conoscenza del significato del termine perugino,
de\la sua origine e del rispetto con cui, ancor oggi, ìe
persone anziane di Lucca e provincia ne fanno memoria.
ll termine perugino designa il contenuto del pozzo nero ed è
stato coniato secoli fa per indicare l'attività di una cooperativa di imprenditori originari di Perugia periodicamente impegnata a svuotare i pozzineri di tutta la città. Tale attività prevedeva il solo e rìconosciuto
compenso da parte degli agricoltori che ne richiedevano
f impiego come concime, usato del resto per
ferúbzzare i campi fin dall'origine della storia dell'uomo.
In Italia forse l'esempio di utilizz azione megl io or ganizzata
dei pozzineri si è avuta nelle marcite, vere e proprie
opere di ingegneria idraulica della bassa milanese. Molti ricorderanno che ancora nella seconda metà del secolo scorso le fogne venivano scaricate nelle campagne e andavano a lambire Ie superfici del terreno, sistemate in modo da agevolare un loro lento scorrimento e l'assorbimento di ciò che convogliavano. Da Melegnano
in giù la gente si lamentava bofonchiando che
"A MiIàn gh'en i cèss, a Melegnàn i udùr" (a Milano ci sono
i cessi, a Melegnano gli odori), ma gli effetti mirabili di tale
pratica erano più che evidenti: il fieno che si raccoglieva
nella pianura padana era costituito da d ue o tre tagli (maggengo,agostano e quando andava bene anche un rachitico terzuolo), mentre in tutta la bassa milanese e nell'attuale provincia di Lodi se ne contavano
sette o otto o anche di più, fino a undici o dodici, e di ottima qualita'. L'articolo esamina questi aspetti
Humic substances and uses thereof in agro-environment
No full textThe present invention relates to the two main categories of humic substances, humic acids and fulvic acids and their use for hindering the propagation and/or contamination with prion infectivity both in agricultural and environmental systems
Humic substances and therapeutic uses thereof
No full textThe present invention relates to the medical field, in particular to the use of natural organic polyanions, i.e. humic substances, HSs, in the treatment of neurodegenerative diseases, such as Prion disease, Alzheimer's and Parkinson's disease
Influence of long-term residue and fertilizer applications on soil humic substances: A study by electrofocusing
No full textSoil samples were taken from the plots of an experimental field that had been treated continuously for 22 years with different residue and fertilizer applications (cereal residues, cattle manure, NH4NO3). The electrofocusing (EF) technique was used to characterize the humic substances extracted from these soils with 0.5 M NaOH. The EF patterns of the organic matter extracted from the soil which had received applications of cattle manure showed many bands focused in the typical pH gradient region of the most humified compounds. The EF patterns of the organic matter extracted from both unfertilized soil and from soils amended with straw appeared to be much less complex. The addition of NH4NO3 did not affect the soil organic matter characteristics investigated with the EF technique. The results obtained show that electrofocusing is a promising technique for the characterization of humic substances and may well be particularly useful in the evaluation of differences that occur in the humic substances in soil due to residue and organic fertilizer applications. © 1992 Williams and Wilkins
CONFORMATION AND AGGREGATION OF METHYLPREDNISOLONE ESTERS OF HYALURONAN BY MEANS OF 1H PULSED GRADIENT STIMULATED ECHO NMR
No full textChromium-Containing Organic Fertilizers from Tanned Hides and Skins: a Review on Chemical, Environmental, Agronomical and Legislative Aspects
No full textA category of chromium (Cr)-containing fertilizers is represented by the fertilizers deriving from byproducts of tanning process. Their use is widespread because of their good agronomic response due to the high content of slow release organic nitrogen (N) and carbon. They do not represent an environmental hazard because only the non-toxic form of Cr(III) is present. Productive processes may involve chemical, enzymatic or thermal hydrolysis. The final product is
characterized by different contents of peptides and free amino acids depending on the type of hydrolysis. Legislations concerning Cr-containing fertilizers is controversial because often do not consider any scientific evidences; nevertheless, the European Union, the United States and countries as Italy, do not set the restriction to Cr(III) and generally only the presence of the toxic form, Cr(VI), is limited. Depending on its two main oxidation forms, Cr issue has been studied for many years. Several authors confirmed that Cr(VI) is carcinogenic, while Cr(III) is an essential trace element in human and animal diet. In soil Cr(III) has low mobility, whereas Cr(VI) is highly water soluble. However Cr(VI) in soil is quickly reduced to Cr(III); on the contrary oxidation of Cr(III) to Cr(VI) is rarely possible because particular conditions must occur. Only a very small fraction of Cr in soil is available to plant uptake and its translocation in edible parts is limited because it is immobilized in roots as Cr(III). Therefore risks of environmental pollution using these fertilizers are negligible; on the contrary they have positive environmental and agronomical effects. The aim of this review is to deal with the category of the organic fertilizers containing Cr derived from tannery processes focusing on its chemical, productive, legislative, environmental and agronomical aspects. Special attention is given to the ambiguous issue of Cr briefly summarizing the most important studies of the last forty years
Studies on coffee roasting process by means of nuclear magnetic resonance spectroscopy
Full text linkThe chemical composition of coffee has been widely investigated, focusing the attention both on main components and trace compounds. Most of these studies have been performed by using liquid and gas chromatography, eventually combined with mass spectroscometry. These techniques, although straight and effective, are time demanding due to the sample pretreatments. Here, we propose high-resolution-magic-angle spinning nuclear magnetic resonance spectroscopy (HR-MAS NMR), a system capable of acquiring highly resolved NMR spectra of gel-like and suspension samples. This approach allowed us to determine the chemical composition of coarsely ground coffee beans of two varieties: Arabica and Robusta. Variation of the concentration of relevant species was monitored as a function of roasting temperature, from green beans to completely roasted. The HR-MAS NMR tool demonstrated to be very powerful for quick chemical composition determination, opening up possibilities for novel applications of this approach in food quality control
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