845 research outputs found
A CONTRIBUTION TO THE STUDY OF A PISA ALLUVIAL PLAIN SECTOR FOR LOW TEMPERATURE GEOTHERMAL ASSESSMENT
The target of this work is to evaluate the possible feeding of the east sector of the Pisa plain hydrogeological system by the Monte Pisano meteoric waters, using a geochemical and geological approach. The study was made considering the Calci basin and the area of the sedimentary plain adjacent at the Calci fan, where spring and well waters have been sampled and analyzed. The analyses of the major and minor elements of the well waters have confirmed a common origin with the springs above the Calci major alluvial fan, showing the same geochemical fingerprint. The isotopic analyses (δD-δ18O) allowed to compute the average altitude of infiltration of the waters. The altitudes obtained for the groundwaters sampled close to the alluvial fan are comparable with the average altitude of the Monte Pisano, confirming the hypothesis of the feeding of this aquifer sector by the Calci alluvial fan. The meteoric waters infiltrate through the debris-alluvial bodies that cover the south-western side of the Monte Pisano slopes reaching the aquifers at the foot of the hills. A possible water contribution to the feeding of about 5*106 m3/yr has been estimated from the hydrologic budget of the drainage basin above the Calci alluvial fan
Comment on: ‘‘The dark nature of Somma-Vesuvius volcano:Evidence from the 3.5 ka BP Avellino eruption’’ by Milia A.Raspini A., Torrente M.M.,
We present here some criticism to the scientific content of the paper of Milia et al. [2007. The dark nature of Somma-Vesuvius volcano:
evidence from the 3.5 ka B.P. Avellino eruption. Quaternary International, 173–174, 57–66] published in Quaternary International.
Milia et al. (2007) interpreted seismic lines in the Gulf of Naples (southern Italy), and inferred the presence of deposits from a large debris
avalanche which occurred just before the Avellino eruption of Somma-Vesuvius volcano. The authors supported their seismic profile
interpretation with on-land stratigraphies and logs. However, we present here different on-land data that demonstrate the inconsistency
of the occurrence of any debris avalanche before or after the Avellino eruption, and we provide also an alternative interpretation for the
observed seismic facies offshore of Somma-Vesuvius
First evidence for a major cover crop effect on arbuscular mycorrhizal fungi and organic maize growth
Arbuscular mycorrhizal fungi are increasingly used in organic cropping systems to increase yields. Although cover crops are largely used in organic farming, there is little knowledge on the impact of cover crops on native mycorrhizal fungi. Here, we studied the effect of cover crop diversity on mycorrhizal colonization in subsequent organic maize cultivars differing in the level of genetic diversity. Experiments were conducted from 2010 to 2012 in a Mediterranean environment. First Indian mustard (Brassica juncea L. Czern.), hairy vetch (Vicia villosa Roth), a mix of seven cover crop species (Mix), and natural vegetation (Control) were cultivated as winter cover crops. Then, an organically and a conventionally bred maize hybrid and three organically bred composite cross populations were cultivated. Mycorrhizal propagule dynamics were measured. Results at juvenile stage show a higher mycorrhizal colonization in maize plants grown after hairy vetch, of 35.0 %, and Mix cover crops, of 29.4 %, compared to Indian mustard, of 20.9 %, and Control, of 21.3 %. The potential of soil mycorrhization decreased of 56.5 % following Indian mustard, higher than that of other cover crops, of 34.1–47.3 %. This finding could be explained by the release of isothiocyanates in soils. Moreover, maize shoot biomass, nitrogen, and phosphorus content across all maize genotypes at juvenile stage increased with mycorrhizal colonization. These findings provide the first evidence of the greater role played by cover crop identity in the enhancement of early mycorrhizal colonization of the subsequent crop and of soil mycorrhizal activity
Organic farming systems for adaptation to and mitigation of climate change: Effects on soil fertility and resource use efficiency
Organic farming is pointed as one of the most sustainable farming practices in terms of environmental sustainability and climate change mitigation potential. At the core of organic farming practices there are practices aimed at improving soil fertility, increasing soil C content and enhancing system biodiversity. A long-term field experiment (LTE) (MASCOT) was started on 2001 in San Piero a Grado, Pisa (Italy) with the aim to compare two different cropping systems, one managed organically and one conventionally, in terms of agronomical, economic and environmental sustainability. In 2016, the MASCOT was redesigned as a full system trial and the organic system was reshaped according to up to date agroecological standards. Climate change adaptation capacity of the two systems is being assessed through agronomic and economic parameters, whilst greenhouse gas emission mitigation potential is mainly expressed in terms of soil C sequestration
Assessing pyroclastic fall hazard through field data and numerical simulation: Example from Vesuvius
A general methodology of pyroclastic fall hazard assessment is proposed on the basis
of integrated results of field studies and numerical simulations. These approaches result in
two different methods of assessing hazard: (1) the ‘‘field frequency,’’ based on the
thickness and distribution of past deposits and (2) the ‘‘simulated probability,’’ based on
the numerical modeling of tephra transport and fallout. The proposed methodology mostly
applies to volcanoes that, by showing a clear correlation between the repose time and the
magnitude of the following eruptions, allows the definition of a reference ‘‘maximum
expected event’’ (MEE). The application to Vesuvius is shown in detail. Using the field
frequency method, stratigraphic data of 24 explosive events in the 3–6 volcanic
explosivity index range in the last 18,000 years of activity are extrapolated to a regular
grid in order to obtain the frequency of exceedance in the past of a certain threshold value
of mass loading (100, 200, 300, and 400 kg/m2). Using the simulated probability method,
the mass loading related to the MEE is calculated based on the expected erupted
mass (5 1011 kg), the wind velocity profiles recorded during 14 years, and various
column heights and grain-size populations. The role of these factors was parametrically
studied performing 160,000 simulations, and the probability that mass loading exceeded
the chosen threshold at each node was evaluated. As a general rule, the field frequency
method results are more reliable in proximal regions, provided that an accurate database of
field measurements is available. On the other hand, the simulated probability method
better describes events in middle distal areas, provided that the MEE magnitude can be
reliably assumed. In the Vesuvius case, the integration of the two methods results in a new
fallout hazard map, here presented for a mass loading value of 200 kg/m2
Net gain: Low-cost, trawl-associated eDNA samplers upscale ecological assessment of marine demersal communities
Marine biodiversity stewardship requires costly and time-consuming capture-based monitoring techniques, which limit our understanding of the distribution and status of marine populations. Here, we reconstruct catch and demersal community compo- sition in a set of 24 fishing sites in the central Tyrrhenian Sea by gathering environ- mental DNA (eDNA) aboard commercial bottom-trawl fishing vessels. We collected genetic material from two sources: the water draining from the net after the end of hauling operations (“slush”), and custom-made rolls of gauze tied to a hollow perfo- rated sphere placed inside the fishing net (“metaprobe”). Species inventories were generated using a combination of fish-specific (Tele02 12S) and universal metazoan (COI) molecular markers. DNA metabarcoding data recovered over 90% of the caught taxa and accurately reconstructed the overall structure of the assemblages of the examined sites, reflecting expected differences linked to major drivers of community structure in Mediterranean demersal ecosystems, such as depth, distance from the coast, and fishing effort. eDNA also returned a “biodiversity bonus” mostly consisting of pelagic species not catchable by bottom trawl but present in the surrounding en- vironment. Overall, the “metaprobe” gauzes showed a greater biodiversity detection power as compared to “slush” water, both qualitatively and quantitatively, strengthen- ing the idea that these low-cost sampling devices can play a major role in upscaling the gathering of data on both catch composition and the broader ecological charac- teristics of marine communities sustaining trawling activities. This approach has the potential to drastically expand the reach of ecological monitoring, whereby fishing vessels operating across the oceans may serve as opportunistic scientific platforms to increase the strength and granularity of marine biodiversity data
Legume Cover Crop Alleviates the Negative Impact of No-Till on Tomato Productivity in a Mediterranean Organic Cropping System
The ecosystem services a cover crop (CC) provides depend enormously on species choice and tillage system. Here, we evaluated the impact of (a) three winter CCs-rye (Secale cereale L.) and squarrose clover (Trifolium squarrosum L.) monocultures and their mixture, and (b) two tillage systems-roller-crimping of CC residue as dead mulch for no-till (NT) systems and incorporating CC residue into the soil as green manure for conventional tillage (CT) systems-on the performance of organic processing tomato, i.e., plant growth, nutrient accumulation, fruit yield, and weed biomass. The assessments took place over two years in field experiments conducted under Mediterranean conditions. At the termination time, rye and mixture were the most productive and the best weed-suppressive CCs. During tomato growing season, squarrose clover regardless of tillage system stimulated tomato growth, Nitrogen content and uptake, and the yield relative to the other cover crops. Nevertheless, NT generally impaired the tomato nutritional status and increased weed biomass compared to CT despite some potential weed control by cover crops. These two aspects caused a significant drop in tomato yield in all NT systems. The results suggested that, despite the multiple benefits the compared CCs can offer in Mediterranean agroecosystems, legume CCs could be the key to developing feasible organic vegetable no-till systems
Application of a multi-species bio-economic modelling approach to explore fishing traits within eligible cetacean conservation areas in the Northern Ionian Sea (Central Mediterranean Sea)
The assessment of the spatial overlap between eligible cetacean conservation areas (CCAs) and fishing grounds could be a strategic element in the implementation of effective conservation measures in the pelagic offshore areas. A multi-species bio-economic modelling approach has been applied to estimate the fishing traits in eligible CCAs in the Northern Ionian Sea (NIS, Central Mediterranean Sea) between 10-800 m of depth, adopting the Spatial MAnagement of demersal Resources for Trawl fisheries model (SMART). Four possible CCAs were defined according to the distribution of cetacean species, their bio-ecological needs, as well as socio-economic needs of human activities, identifying a Blue, Red, Orange and Green CCAs in the NIS. SMART spatial domain was a grid with 500 square cells (15x15 NM). The analysis was conducted for the period 2016-2019, considering the Otter Trawl Bottom (OTB) fleet activities in the study areas through the Vessel Monitoring System. The spatial extension of fishing activities, hourly fishing effort (h), landings (tons) and economic value (euros) for each CCA and the NIS were estimated as yearly median values. Fishing activities were absent in the Blue CCA, where the presence of the submarine canyon head does not offer accessible fishing grounds. The hourly fishing effort in the Green area accounted for about 22% (3443 h) of the total hourly effort of the NIS, while the Orange and Red areas were about 8% (1226 h) and 2% (295 h), respectively. The Green CCA corresponded to about 14% (36 tons) of the total landings in the NIS, whereas the Orange and Red areas represented about 9% (22 tons) and 6% (16 tons), respectively. The Green CCA accounted for about 13% (156 thousand euros) of the total economic value of the NIS, while the Orange and Red areas represented about 6% (69 thousand euros) and 4% (44thousand euros), respectively. Results showed no or negligible negative effects on trawl activities by potential spatial restrictions due to the establishment of CCAs highlighting the importance to consider spatially integrated information during the establishment process of conservation areas for cetacean biodiversity according to the principles of Ecosystem Based Management
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