Effetti della siccità sull'abbondanza e distribuzione dei macroinvertebrati

The role of disturbance on structuring animal communities is a central subject in the ecological research. In particular in the intermittent systems river, the drought event seems to determine the macroinvertebrate community structure. In such context, we analysed the macrobenthos of a Sardinia intermittent stream (Rio Pula, Cagliari). The study was carried out on 16 sites in 3 years (from 2000 to 2002) with seasonal samplings (spring and autumn) of the macroinvertebrate community. The results have shown a temporal stability of community and a spatial change of community structure along the river basin determined by drought frequency. Finally, patterns of spatial change in the guild composition seem to be partly in contrast with the River Continuum concept

Preliminary Assessment of Radiolysis for the Cooling Water System in the Rotating Target of {SORGENTINA}-{RF}

The SORGENTINA-RF project aims at developing a 14 MeV fusion neutron source featuring an emission rate in the order of 5-7 x 10(13) s(-1). The plant relies on a metallic water-cooled rotating target and a deuterium (50%) and tritium (50%) ion beam. Beyond the main focus of medical radioisotope production, the source may represent a multi-purpose neutron facility by implementing a series of neutron-based techniques. Among the different engineering and technological issues to be addressed, the production of incondensable gases and corrosion product into the rotating target deserves a dedicated investigation. In this study, a preliminary analysis is carried out, considering the general layout of the target and the present choice of the target material

Spatial and temporal variations of detritus breakdown rates in the River Flumendosa basin (Sardinia, Italy)

Here we analyse in a 5th order Mediterranean river (River Flumendosa, Sardinia, Italy) spatial and temporal variations of plant detritus processing, a key functional aspect of river ecosystems. Decay rates of dead leaves (Phragmites australis) were studied during the fall-winter and spring-summer seasons at 17 sites distributed among 5 stream orders. Litter decay rates varied more, and were higher in spring-summer than in fall-winter. On the spatial scale, patterns of decay rate variation among sites and orders did not vary between seasons; seasonal variation was low in reaches with slow rates and high in reaches with fast rates. Data analysis showed a spatial pattern of increasing reed detritus decay rates with increasing stream order

Influence of drought and abiotic factors on Phragmites australis leaf decomposition in the River Pula, Sardinia, Italy

Temporal and spatial patterns of Phragmites australis leaf decomposition and the relative influence of summer droughts and abiotic features were studied in a Mediterranean-type river basin, the River Pula. Reed processing rates varied among seasons and sites, being on average significantly faster in the cold season (i.e., winter-spring) than in the warm seasons (i.e., summer-fall) and in low rather than high stream order reaches. On the other hand, at sites protected from summer drought events (i.e., wet sites), decay rates were faster in the warm than in the cold season. Along stream order, leaf decay rates were significantly faster at wet sites than at sites suffering from summer droughts. Summer drought events explained 44% of reed decay rate spatial variability, and major water abiotic parameters explained an additional 8%

Preliminary Assessment of Radiolysis for the Cooling Water System in the Rotating Target of SORGENTINA-RF

The SORGENTINA-RF project aims at developing a 14 MeV fusion neutron source featuring an emission rate in the order of 5–7 × 1013 s−1. The plant relies on a metallic water-cooled rotating target and a deuterium (50%) and tritium (50%) ion beam. Beyond the main focus of medical radioisotope production, the source may represent a multi-purpose neutron facility by implementing a series of neutron-based techniques. Among the different engineering and technological issues to be addressed, the production of incondensable gases and corrosion product into the rotating target deserves a dedicated investigation. In this study, a preliminary analysis is carried out, considering the general layout of the target and the present choice of the target material