1,720,980 research outputs found
Geochemistry of recent sediments in the Lagoon of Venice.
No full textGeochemical researches have been carried out on bottom sediments subdivided in two levels (0-2 cm; 3-10 cm). The top sediments differ from deeper ones for some significant elements, such as Al, K, Fe, Mg and P, Zn, Pb, Cd. To evaluate the anthropogenic contribution, the heavy metals contents detected in two levels were discussed. -from Author
Il ruolo delle caratteristiche mineralogiche e fisiche dei sedimenti nei processi d'inquinamento in un'area tipo della Laguna Veneta.
No full textAmphibole composition in rock of Predazzo volcano-plutonic complex (Southern Alps, Italy)
No full textSUSPENDED MATTER PROPERTIES AND ITS ROLE IN POLLUTANT TRANSFER FROM THE RIVER TO THE SEA - CASE-STUDY - ADIGE RIVER ADRIATIC SEA
No full textSuspended matter and bottom sediments have been investigated in the Adige River estuary (Northern Adriatic Sea) and their role in the heavy metals transfer from land to sea. The observed similarity of the geochemical and mineralogical composition between the riverine suspended matter and the marine sediments just at the Adige mouth reveals that most of the riverborne suspended particles settle in the prodelta area together with the associated heavy metals. Among the various toxic elements examinated, chromium has a peculiar behaviour, which indicates the man's influence on its biogeocycle. © 1986
The Role of Suspended Matter in the biogeochemical cycles in the Adige River Estuary (Northern Adriatic Sea)
No full textSuspended matter and sediments from the Adige River mouth were analysed in an attempt to elucidate the transfer of heavy metals from the river to the sea. The vertical profile of grain-size spectra of suspended matter in front of the river mouth has shown that the riverine particles are limited to the upper brackish layer. Particulate matter was found to have a large specific surface area, up to 20 m2 g-1 in the estuarine sample. High quantities of quartz and phyllosilicates (micas and clay minerals) were found in the riverine suspended matter. The quartz content of the suspended matter from the brackish layer was found to be diminishing and with the organic matter becoming the essential component (22%). Higher levels of trace metals were usually detected in suspended matter samples (40 ppm Ni, 200 ppm Cr, 60 ppm Pb, 100 ppm Cu, 320 ppm Zn, and 0·9 ppm Cd) than in sediments. The observed similarity of physico-chemical, mineralogical and geochemical characteristics of riverine suspended matter and recent marine sediments, indicates that most of the riverborne particulate matter is deposited in the proximity of the Adige River mouth. The peculiar characteristics of the chromium level (high bulk concentration and its abundance in the organic fraction of the particular matter) when compared to the other trace metals, indicates the anthropogenic influence on its biogeocycle. © 1987
Major element geochemistry of sediments from the Ross Sea, Antarctica
No full textIndicates the silicate composition of the examined sediments. The different concentrations of the major elements, their geographical distribution and inter-relations allowed the distinction of three populations of samples with specific geochemical characteristics and locations. -from Author
Le Scienze della Terra nello studio dell'ambiente: una esperienza didattica interdisciplinare
No full textGeochemical considerations on trace element distributions in suspended matter and sediments at the river-sea interface, Adige River mouth, northern Adriatic sea
No full textThe particulate matter at the Adige River mouth has been investigated in order to determine the natural geochemical processes in the estuarine environment, and the anthropogenic influence on the biogeochemical cycling of heavy metals. The determination of suspended matter and sediment physico-chemical characteristics (grain size, mineralogy, organic matter content, specific surface area), and of concentrations of major and trace elements in the Adige River mouth in different hydrological conditions, has shown that this mouth acts as a trap for most heavy metals. Heavy metals were found to be preferentially bonded to the particulates, and in the estuarine mixing zone scavenging of most dissolved metals occurs, due to salinity and pH gradients, and to the formation of new particulate organic matter. The surface characteristics of suspended particulate matter [fine grain size, abundance of clay minerals, large specific surface area (SSA), organic and inorganic coatings] favour the adsorption of heavy metals. The sedimentation pattern (rapid deposition due to flocculation of fine particles, and to low environmental energy and estuarine circulation) causes accumulation of particulate matter, enriched in heavy metals, in the prodelta zone. Moderate anthropogenic influence on Cu, Pb, Cd, and Cr concentrations has been recognised in the Adige River. The environmental fate of these elements is determined by the same natural processes, and therefore accumulation in front of the river mouth occurs. The elevated partitioning in the organic phase of the anthropogenically influenced elements, could favour their mobility in different environmental conditions. © 1989
Processi di accumulo dei metalli pesanti nei sedimenti, fattori ambientali ed influenza antropica. il caso della Laguna di Venezia.
No full textSpatial and temporal evolution of heavy metals accumulation in sediments of the Lagoon of Venice: environmetal implications
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