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Fattori del suolo che influenzano la disponilità dei metalli per le piante
No full textThe knowledge of the interactions between metals and soil components is of great importance to
evaluate the availability of the trace elements to plants as well as the potential danger of metals to
soil and water beds. The main factors affecting the equilibrium and interaction meccanisms
between metals and the most active soil costituents in the absorption processes are discussed in
this paper
Assorbimento di alcune triazine simmetriche su una bentonite di Uri (Sardegna)
Full text linkThe adsorpition of six s-triazines of the chloro- and methoxy-analogue
series on a bentonite from Uri (Sardinia) was studied. The H-bentonite
shows a higher adsorption than the Na-bentonite. The order of adsorbabiIity
of chloro-s-triazines was trietazine > atrazine > propazine; by me·
thoxy-s-triazines it was simetone > atratone > prometone.
The amount of simetone adsorbed by the H-bentonite occurred in
excess of the CEC. The relationship between adsorption, solubility and
lenght of the lateral chain of the s-triazine was confirmed. The adsorption
was mainly due to van der Waals forces, H-bonding and ionic exchange
Contributo dell'argilla e della sostanza organica alla capacità di scambio cationico delle terre brune della Sardegna Nord-Orientale
Full text linkThe contributions of clay and organic matter relative to 24 samples
collected from non calcic brown soils of N-W Sardinia - were measured
using statistical analyses. Within the limits of the standard errors the
regression coefficients of day and organic matter increase linearly with pH.
The average contribution to CEC of day decreased from 64% at pH 3 to
300% at pH 8. The clay CEC was 30, 34, 39 meq per 100 g. al pH 3,5 and 8,
respectively, while that of the organic matter was 62, 131, 231 meq per 100 g.
The high increase of CEC between pH 5 and 8 was interpreted in view
of eventual liming of cultivable soils
Effetto dei detersivi commerciali sullo sviluppo di alcune specie vegetali di interesse agrario
Full text linkExperiments have been realized on some agricultural vegetable species
to study their growth behaviour in the presence of detersive, using to the
purpose faur commercial detersives. The greatest phototoxic effects are
felt by Lolium. Medicago and Tripholium. The detersive containing the
no-ionic tensio-active shows the most depressing action
Morphological, chemical and mineralogical characterization of some soils developed on hard carbonate rocks in Sardinia
Full text linkThis preliminary note considers 19 profiles of Sardinian soils developed on hard limestone,
dolomitic limestone and dolomite of different age and territorial condition, reporting on the
description of the profiles and their physical, chemical and mineralogical characteristics. The
results indicate that the soils examined belong to xeric subgroups of three orders: Entisols,
Inceptisols and Alfisols.
All the profiles show a clay texture and the clayey constituents are related to the degree of soil
evolution
Indagine sull'impatto ambientale dei reflui oleari a seguito del loro smaltimento nel terreno
Full text linkFour different doses of olive mill waste were spread on the calcareous soil of a vineyard. No
significant alteration of the soil properties was observed even at the highest dose of OMW
whereas an active dynamism of organic matter and mineral elements was registered
Sull'origine delle terre rosse in Sardegna: gli elementi in traccia nella caratterizzazione di suoli e rocce madri
Full text linkThe trace elements in the characterization or red soils and parent rocks.
The genesis of red soils (Terre Rosse) formed on limestone or dolomite rock bed is yet an unsolved
question. A theory suggests that these soils are the final step of an intense decarbonation process of
the parent rock followed by the change of the materials in the insoluble residue into iron oxides
and clay minerals.
A number of trace elements, most1y transition metals, was determined in Sardinian Terre Rosse and
parent rocks by instrumental neutron activation analysis performing different irradiations in the
TRIGA Mark II nuclear reactor of the University of Pavia. Induced radioactivity measurement was
carried out by gamma-ray spectrometry using a High Purity germanium detector coupled to an
analyzer-computer system. The same elements were also determined in some standard reference
rocks, released by United States Geological Survey, in order to evaluate the accuracy of the
employed analytical method.
Average values of the trace element content in the Terre Rosse and in the parent rocks are presented
and discussed, together with the evaluation of precision and accuracy. Trace element profiles at
different horizons are reported as well. A comparison of trace element distribution among soils
belonging to the same geological era is also presented
Electrochemical properties of Fe and Al hydroxides as affected by different supporting electrolytes
No full textPotentiometric titration curves of Fe and Al hydroxides, carried out in presence of different electrolytes
(KCI, Kbr, KI, KNO3, KCIO4) were elaborated by the Stern theory through a computered program.
The zero points of charge (zpc), calculated from the intersection point of the titration curves at different
ionic strenght, varied from pH 7.10 to pH 7.65 for Fe hydroxides and from pH 9.10 pH 9.45 for Al hydroxi
des.
For Fe compounds, a good match was found between the experimental values and those calculated by
the Stern model. High deviations were observed only with KCIO4, in whose presence a lowering of the zpc
was registered.
Also in Al hydroxides the proposed model was not reliable below zpc, indicating that the surface interac
tions are somewhat involved in specific adsorption phenomena
Describing the adsorption of potential determining ions on variable charge mineral surfaces
No full textA computer program was developed to elaborate the titration curves of amphoteric surfaces according to
the double layer theory. The zpc, identified from the intersection point of the titration curves carried out
at different ionic strengths, fell at pH 3.15, 9.45 and 7.65 for Si, AI and Fe hydroxides, respectively. The
Stern model described quite satisfactorily the relation between σ0and ψ0. Some problem was presented
by Si surfaces which were then treated by a different calculation procedure.
The δ values, the Stern layer thickness, were very high for the SI surfaces and increased with decreasing
ionic strength. A different behaviour was showed by AI and Fe hydroxides; in these cases δ values were
very low and increased with increasing electrolyte concentration. These results were discussed in terms
of surface structures and activity of the supporting electrolyte
Interazione acido umico-metalli pesanti in un suolo boschivo
Full text linkAnalytical data on the heavy metal content of humic acid extracted from the surface soil samples
of a wooded area in southern Sardinia and correlations between soil and humic acid metal content
are reported. A tentative approach to the determination of humic acid-heavy metal complex stability
constants, based upon Langmuir's isotherm is proposed
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