Northern Po Research Articles

The Pleistocene tectono-stratigraphic evolution of the northern Po Plain (Italy) around the Castenedolo and Ciliverghe hillocks

AbstractWe studied the Pleistocene subsurface stratigraphy of an area in the northern Po Plain around the isolated tectonic hillocks of Castenedolo and Ciliverghe (Brescia, Italy) in order to estimate their long-term rates of tectonic deformation. Integrated stratigraphy of a new 100-m-long core (RL13) allowed better definition of the regional Y (0.45 Ma) and R (0.87 Ma) surfaces and the related magnetostratigraphically calibrated PS1, PS2, and PS3 depositional sequences. The Y surface in the RL13 core was placed at the base of the PS3 proximal braided river system that was deposited during middle Pleistocene within the Brunhes chron. The R surface is considered to be eroded within the PS2 braid-plain deposits at ca. 0.87 Ma between the top of Jaramillo subchron and the Bruhnes chron during the late Early Pleistocene.Based on different datasets, we evaluated the sedimentation rate, which has decreased from 0.09 mm/yr with deposition of PS2, to 0.06 mm/yr with deposition of PS3. The tectonic uplift, with an average rate of ~0.1 mm/yr in the last ca. 0.87 Ma, is interpreted to be associated with a fault and related fault-propagation folding. The Castenedolo and Ciliverghe hillocks then formed due to tectonic uplift during a change in the sedimentation regime since 0.45 Ma.

Irrigation practices affect relationship between reduced nitrogen fertilizer use and improvement of river and groundwater chemistry

In the last decades, the intensification of agricultural practices has deeply altered nitrogen (N) and water cycles. Climate change and drought events are expected to further increase the human impacts on the hydrological and biogeochemical cycles, and these impacts are gaining the attention of the scientific community. Here we show how the Chiese River watershed (Lombardy Region, Italy) represents an interesting opportunity to analyse the effects of traditional irrigation practices on N contamination in the context of water scarcity. During summer, flood irrigation is mostly sustained by groundwater withdrawal. Additional water withdrawals from the river contribute to the dry out of the Chiese River. The use of wells for irrigation over permeable and fertilized soils and the percolation of nitrate (NO3-) from the vadose zone to groundwater result in the accumulation of NO3- in groundwater and limited N losses via denitrification due to dominant oxic conditions. These practices contrast other measures targeting the reduction of N excess over arable land. In the Chiese River watershed, the N surplus from Soil System Budget calculations decreased by 43% since the early 2000 s but NO3- concentration in groundwater remained high and stable (up to 98.0 mg NO3- L−1). The dried-out Chiese River gains groundwater and NO3- concentration at the river mouth approaches 32.2 mg NO3- L−1. Our results suggest how the mismanagement of the watershed (overabundant fertilization and flood irrigation using groundwater) increases the N concentration both in the river and groundwater, leading to the violation of both Nitrate and Water Framework directives. We anticipate our assay to be a starting point for the conversion of the northern Po Plain to more efficient irrigation and fertilization practices to contrast severe droughts driven by climate change like the one who struck the Po Plain in summer 2022.

Do the barrier islands of the Po Delta constitute an ecological trap for colonising Slender-billed Gulls Larus genei?

Abstract The Slender-billed Gull (Larus genei) breeds with a scattered distribution on an extensive nesting area, ranging from India and Afghanistan in the East to the Iberian Peninsula in the West, including the Mediterranean and the Black Sea. A number of habitats are used for breeding, such as sand-spits and beaches along coasts and islands of land-locked seas, steppe lakes, but also brackish or freshwater lagoons near river deltas. Sea level rise dramatically affects coastal sites, thus being the greatest threat to the survival of many seabird species, including gulls. This note describes habitat selection, breeding success and causes of failure of Slender-billed Gulls during their colonisation of the northern Po Delta (NE Italy) during 2018–2022. Slender-billed Gulls colonised the northern Po Delta in 2018. Six colonies were found during the study period. Birds used both natural barrier islands and artificial dredge islands. Productivity in the first five years after the colonisation event was zero, mostly due to colony sites being flooded by high tides and storms. If Slender-billed Gulls will switch to nest in nearby fish farms, these could provide plenty of suitable breeding sites, safe from tidal flooding and with very low predation pressure, allowing sufficient productivity. At the moment, Slender-billed Gulls are unsuccessful in colonising the barrier islands of the Po Delta.

The First ‘Urnfields’ in the Plains of the Danube and the Po

Archaeological research is currently redefining how large-scale changes occurred in prehistoric times. In addition to the long-standing theoretical dichotomy between ‘cultural transmission’ and ‘demic diffusion’, many alternative models borrowed from sociology can be used to explain the spread of innovations. The emergence of urnfields in Middle and Late Bronze Age Europe is certainly one of these large-scale phenomena; its wide distribution has been traditionally emphasized by the use of the general term Urnenfelderkultur/zeit (starting around 1300 BC). Thanks to new evidence, we are now able to draw a more comprehensive picture, which shows a variety of regional responses to the introduction of the new funerary custom. The earliest ‘urnfields’ can be identified in central Hungary, among the tell communities of the late Nagyrév/Vatya Culture, around 2000 BC. From the nineteenth century BC onwards, the urnfield model is documented among communities in northeastern Serbia, south of the Iron Gates. During the subsequent collapse of the tell system, around 1500 BC, the urnfield model spread into some of the neighbouring regions. The adoption, however, appears more radical in the southern Po plain, as well as in the Sava/Drava/Lower Tisza plains, while in Lower Austria, Transdanubia and in the northern Po plain it seems more gradual and appears to have been subject to processes of syncretism/hybridization with traditional rites. Other areas seem to reject the novelty, at least until the latest phases of the Bronze Age. We argue that a possible explanation for these varied responses relates to the degree of interconnectedness and homophily among communities in the previous phases.

Sensitivity, Hazard, and Vulnerability of Farmlands to Saltwater Intrusion in Low-Lying Coastal Areas of Venice, Italy

Saltwater intrusion is a growing threat for coastal aquifers and agricultural practices in low-lying plains. Most of the farmlands located between the margin of the Southern Venice lagoon and the Northern Po delta, Italy, lie a few meters below mean sea level and are drained by a large network of artificial channels and hydraulic infrastructures to avoid frequent flooding and allow agricultural practices. This work proposes an assessment of the vulnerability to saltwater intrusion, following a new concept of the hazard status, resulting in combining the depth of the freshwater/saltwater interface and the electrical resistivity of the shallow subsoil. The sensitivity of the farmland system was assessed by using ground elevation, distance from freshwater and saltwater sources, permeability, potential runoff, land subsidence, and sea-level rise indicators. Relative weights were assigned by a pairwise comparison following the Analytic Hierarchy Process approach. The computed vulnerability map highlights that about 30% of the farmlands is under strong and extreme conditions, 28% between marginal and moderate, and 40% under negligible conditions. Results from previous vulnerability assessments are discussed in order to explain their differences in terms of hazard status conceptualization and sensitivity characterization of farmland system.

Long term trends and breeding parameters of Gull-billed Tern <em>Gelochelidon nilotica</em> in three Italian coastal sites

Between 2001 and 2018 colonies of Gull-billed Tern were monitored in large wetland complexes of Veneto (lagoon of Venice and the Northern Po Delta) and Sardinia (western and southern) regions. Most of the colonies settled in man-made structures such as islets, levees, dams, located inside fish farms, fish ponds and salt pans. Laying took place around half May until early June (Veneto), with eggs occurring in the nests until half July (Sardinia). Colonies had 3-230 pairs, with several instances of isolated pairs; colonies were mono- or plurispecific, with other Charadriiformes. The number of eggs per clutch was 2.6±0.6 (N=111, 1 SD) in the Venice lagoon, 2.6±0.6 (N=182) in the Po delta, 2.3±0.70 (N=1007) in Sardinia; hatched eggs were 2.2±0.6 (N=111), 2.0±0.7 (N=182) and 1.7±0.67 (N=40) per nest, respectively. The most important cause of breeding failure was due to flooding of nesting sites, due to the rapid increase of water levels inside fish farms and salt pans. During the 2001-2018 years, the Gull-billed Tern nested regularly in Sardinia, whereas in the Po Delta the first nesting occurred in 2001 and in the lagoon of Venice in 2008. The whole population ranged between 34 and 417 pairs until 2017 (223.6±113.4, N=17), with a sudden increase up to almost 1,000 pairs in 2018; the overall trend is of strong increase (p<0.01), with an annual rate of 10.5%.

LA "GONFOLITE LOMBARDA": STRATIGRAFIA E SIGNIFICATO NELL'EVOLUZIONE DEL MARGINE SUDALPINO

The Oligocene-Miocene succession of the "Gonfolite Lombarda" outcrops in Western Lombardy and is largely represented in the subsurface of the northern PO Plain. In the this group was considered as a typical example of post- orogenic molasse deposit. The new data suggest that it represents a clastic wedge infilling a deep foreland basin flanking a zone of continental collision. The stratigraphic evolution of the succession strictly reflects the tectono-sedimentary evolution of the basin.
 The succession (almost 3000 m thick) between Como and Varese covers a time span from late early Oligocene (late Rupelian) at least to early Miocene (Burdigalian). It consists of clastic sediments deposited in a deep-sea environment. Both the benthic Foraminifera and the macrofossil assemblages indicate that these sediments were deposited in the epibathial zone (from 500-700 m to 1000-1300 m) throughout all the time span considered. The succession can be splitted in two main segments based on their different sedimentary characters and because they are separated by a regional unconformity corresponding to a hiatus of several million years. The lower one is represented by the Chiasso Formation (about 170m thick) and the upper one by the Gonfolite Group s. Str. (about 2800 m thick).
 The Chiasso Formation is a depositional sequence late Oligocene (late Rupelian to early Chattian) in age. It consists of mudstones and rare thin-bedded turbidites, representing slope or slope-base deposits. The overlying Gonfolite Group represents the build-up of several deep sea fan systems one on top of the other during the very late Oligocene (late Chattian) to the early Miocene (Aquitanian- Burdigalian) and perhaps to the middle Miocene. Resedimented conglomerates infilled deeply incised canyons confined by natural levees in their distal part. The canyons evolved laterally and distally to still partly confined sandy depositional lobes during the early Miocene.
 In the Gonfolite Group three depositional sequences could be recognized. The first one is represented by the Como Conglomerate (800-1500 m thick) and of some heteropic formations, covering a time span from late Chattian to early Burdigalian. This depositional sequence represents an asymmetric megacycle with an initillly very rapid progradation of the conglomeratic system followed by its gradual regression and, in the Como area, by a westward shift of the system axis. Moreover, it is worth mentioning that pebbles of granodiorite-diorite called "ghiandone and serizzo" of the Val Masin0-Val Bregaglia Massif make their appearance already in the basal part of the Como Conglomerate.
 The second depositional sequence consists of the Lucino Conglomerate (800-1000 m thick) and of some heteropic formations. It represents a gradual progradation of the whole deep sea fan system during the late earIy Miocene (Burdigalian).
 In the Varese area, the Gurone Sandstone (120 m thick) may represent a third depositional sequence, which because of its stratigraphic position is younger than the late Burdigalian, and it appears to be deposited prior to the late Miocene (Tortonian).
 The "Gonfolite Lombarda" basin was interested by an intense and continue tectonic activity with at least two periods of "crisis" occurring in the late Chattian and in the early Burdigalian. Because of the strong tectonic Control it's difficult to correlate the "Gonfolite Lombarda" depositional sequences with the generalized sea level curves.

Long-term drivers and impacts of abrupt river changes in managed lowlands of the Adige River and northern Po delta (Northern Italy)

We analysed the millennial-scale evolution of the alluvial systems of the Po and Adige rivers around the city of Adria, through the analysis of remote sensing images, digital terrain models, historical maps, and the execution of manual cores across the main alluvial ridges. Selected organic samples were radiocarbon dated.Results show that floodplain sedimentation dominated the area until 4.3–4.0 ka cal BP, followed by aggradation of a major alluvial ridge of the Po River (Adria ridge) until 2.6 ka cal BP. Due to a major upstream avulsion, the Po River shifted tens of kilometers to the south, and the minor Tartaro River started flowing through ancient Adria bringing stable geomorphic conditions. In the 10th century AD, the opening of two crevasse channels on the right bank of the Adige River, the Castagnaro and Malopera rivers, initiated the aggradation of the alluvial ridge of the Tartaro River at Adria. This happened during the Medieval Climate Anomaly, in a period of enhanced flooding recorded in Northern Italy, in the Alps and the Mediterranean basin. Extensive peat sedimentation followed since the 11th century, indicating a decrease of overbank flooding and silting by the Tartaro River due to concurrent early management of the crevasses, proximal sediment accumulation, and favorable regional climatic conditions. Fluvial sedimentation started again in the early 15th century, due to the reactivation of the Castagnaro and Malopera crevasses. This happened at the beginning of the Little Ice Age in a period of recurrent flooding of the Adige River, but human-induced modification of channel width and depth may have concurred. Overall aggradation along the Tartaro ridge led to the deposition of up to 4 m of sediment, and the complete burial of an early Medieval church in the city of Adria. The end of this sedimentary event predates the 17th century, and relates to efficient river management actuated by the Venetian Republic.Our investigation highlights how a major avulsion of a large river such as the Po can abruptly change the environmental conditions of large stretches of alluvial plain, allowing the development of an urban settlement on the former floodplain. It further shows that such favorable setting can be suddenly modified by the opening of crevasse channels tens of kilometers away, if water and sedimentary connectivity is allowed. Adria community was resilient to flooding and silting and always attempted to manage the crevasses, but its efforts were counterbalanced by fluctuating climatic conditions.

Electric circuit theory applied to alien invasions: a connectivity model predicting the Balkan frog expansion in Northern Italy

Invasive species are a major threat to biodiversity and alien herpetofauna already caused conservation problems in Italy and in the world. Pelophylax kurtmuelleri (Gayda, 1940) is a water frog native to Southern Balkans, that was introduced in NW Italy (Liguria) in 1941, from where it has spread to Piedmont, Lombardy and recently to Emilia Romagna. Surprisingly, during its expansion, the Balkan frog seemed not to be able to cross the Po River (with a single exception). So, we investigated the reasons for such directional limitation of range expansion, focusing on the potential role of the Po River. Combining ecological niche and connectivity models, we adopted a two-step process in order to assess: (i) if the habitat suitability differs between the two sides of the Po Plain; (ii) if the Po River could act as a barrier in terms of dispersal. Results showed that the northern side of the plain seems less suitable than the southern one, even if many suitable patches occur along the main left tributaries of the Po River and in the hilly part of the plain. The Po River behaves like a barrier for the Balkan frog, but the only known point on the north bank of the river indicates that it may be able to only slow the dispersal and not to completely stop it. So, the most probable interpretation for the absence of the Balkan frog from the Northern Po Plain, is the combination of habitat suitability and connectivity issues: the former makes less probable that new viable populations can establish in the North, the latter decreases the northwards flux of the frogs. Given these findings, the Balkan frog seems able to spread in the whole Northern Italy and the colonization of the northern Po plain could happen shortly.

High resolution climate precipitation analysis for north-central Italy, 1961–2015

Observational daily precipitation data from a group of 1762 stations over north-central Italy and adjacent areas are used to produce a high resolution daily gridded precipitation analysis covering the period from 1961 to 2015. Input data are checked for quality, time consistency, synchronicity and statistical homogeneity and the final result has been used to describe the spatial and temporal variability of precipitation over the area. Data are interpolated using a modified Shepard scheme and the interpolation errors are compatible with those presented in Isotta et al. (Int J Climatol 34(5):1657–1675, 2014). The analysis is compared with other similar products available over the area considered, and differences and similarities are described, taking into account the impacts of different spatial resolution and time coverage. The data set is used to describe local climate with respect to precipitation, including mean values and seasonality, by using a group of climate annual and seasonal indices: cumulated precipitation, maximum number of consecutive dry days, frequency of wet days, mean precipitation intensity and 50th and 90th percentile of daily precipitation over a season. The linear trends over the full period of these indices are described and compared. It is shown that although the time series of area average total annual precipitation over north-central Italy does not show significant linear trends, these are present locally. In particular, significant negative trends of annual total precipitation are found in central Italy and in the inner part of northern plains, while significant positive linear trends are present in several areas over the Alps and over the Liguria coast. The seasons most affected by changes in precipitation are summer and autumn, which, in most areas, are the driest and wettest seasons. In summer, significant positive trends in total precipitation have been found in areas close to the northern national borders, while significant negative trends are located elsewhere. The number of wet days is significantly decreasing over most of the domain, but the 90th percentile of precipitation is significantly increasing over most of the Alpine area and northern Po Valley. Over the southern part of the Po Valley and central Italy summer precipitation is significantly becoming less frequent and, generally, less intense. In autumn, total precipitation is characterised by significant positive trends over large areas in Northern Italy and by significant negative trends in inner areas of the Central Apennines. The trend patterns present great similarities with those of the 90th percentile of daily precipitation for the same season. The maximum length of dry spell is significantly decreasing in autumn over most areas, including central Italy, while the number of wet days presents negative but mostly non significant trends over the whole domain.

Continental and marine surficial water – groundwater interactions: the case of the southern coastland of Venice (Italy)

Abstract. Understanding the continental-marine surficial water–groundwater exchanges in transitional coastal environments is really challenging at large scale. It requires an image of the saltwater–freshwater relationship which is difficult to be obtained especially in wetlands, lagoons, and marine areas. This study is focused on the coastland of the southern Venice lagoon – northern Po river delta (Italy), a precarious environment subject to both natural changes and anthropogenic pressures. Here, saltwater severely affects farmlands and aquifers. We used an airborne electromagnetics (AEM) survey with the goal of characterizing the continental and marine surficial water–groundwater interactions in such coastal region. The AEM survey allowed depicting a clear image of the fresh water–saltwater occurrence in shallow aquifers along mainland-lagoon – littoral-sea profiles, up to 20 km long. The results reveal that continental groundwater is located in the lagoon subsoil below a 10–20 m thick saline aquifer and extends down to 70 m depth. The whole low-lying farmland located south of the lagoon margin is seriously affected by saltwater contamination, which occurs from a few to about 50 m depth. The integrated analysis of AEM, seismic and borehole data shows that buried morpho-geological structures, such as paleo-channels and over-consolidated clay units control the saline contamination from the lagoon and the sea into the coastal aquifer system.

Water matters. Geoarchaeology of the city of Adria and palaeohydrographic variations (Po Delta, Northern Italy)

Adria is located in the northern Po delta at the edge of the Venice Lagoon, a sector of the Po Plain that was built by the late Holocene geomorphic activity of the Po, Adige and Tartaro rivers. Early settlements are dated to the Middle Bronze Age, and the city developed as a major urban centre during the Iron Age and Roman times. In the early Middle Ages, Adria survived as a local religious centre in the Venetian area, as evidenced by the existence of a 9th century AD church. The superimposition of archaeological deposits led to the upbuilding of an anthropogenic mound rising up to 5m above the surrounding plain. The aim of this investigation is to understand the evolution of the city of Adria from the 1st millennium BC to the Middle Ages, and its relationships with the rearrangement of the river network and connected palaeogeographic setting.The area was studied through the analysis of historical cartography, aerial photographs, a digital terrain model, archaeological data from the archives of the Soprintendenza Archeologia del Veneto, geological corings and a cone penetration test. New stratigraphic data have been acquired through the execution of 21 manual boreholes up to 5m in depth with an Edelman combination-type auger. Radiocarbon datings were carried out on selected peat samples.The analysis of the elevation above sea level of different stratigraphic data has exposed the stages of the evolution of the city, starting from the 6th century BC through Roman times and post-Antiquity, revealing the extension of the archaeological mound in the southern part of the modern city. The growth of the mound took place in four phases, dated to the 6th–5th centuries BC, 4th–3rd centuries BC, 1st century BC–1st century AD and post-Antiquity. The presence of a buried soil at the top of the Po deposits, coupled with radiocarbon dating of extensive peat layers, has allowed the reconstruction of the stratigraphy of the alluvial succession, and to correlate it with the archaeological record. The buried soil at the top of the Po deposits lies below the 6th century BC archaeological levels in the lowest part of the archaeological mound. On this same palaeosurface the first 9th century AD church was built. Two alluvial events buried this church under about 2m of overbank fines, turning it into an underground hall, known as the ‘crypt’ of the modern San Giovanni church. These alluvial events are attributed to the Tartaro River, with a probable contribution by the Adige River. The first alluvial event took place between the 9th and 11th centuries AD. In the 11th–15th centuries AD, a marshy area extended north, west and east of the city centre, as evidenced by an extensive peat layer that was buried by the second alluvial event later than the 15th century AD.

The interplay between adjacent Adige and Po alluvial systems and deltas in the late Holocene (Northern Italy)

The alluvial plain behind the southern Venice Lagoon, in northern Italy, is characterised by the presence of a complex network of alluvial ridges formed by the aggradation of channel deposits and natural levees. They are the geomorphological products of the interaction between the Adige and Po during the late Holocene. New geomorphological and stratigraphic data provided a detailed reconstruction of the evolution of the Po-Adige alluvial plain and allowed for defining the relation with the migration of delta lobes in the southern Venice Lagoon and near the Adriatic coast. Three cross sections (total of 28 manual boreholes) were obtained using a hand auger through two alluvial ridges built by the Adige River: the first two on the Conselve ridge (in the locations of Conselve and Santa Margherita, respectively) and the third across the modern Adige alluvial ridge. Radiocarbon dating was carried out on 9 peat samples. These data, coupled with a DTM, allowed the identification of a confluence between the Adige and Po during the Bronze Age. They also enabled the identification of the timing of major Adige and Po avulsions and the correlation with the 5.0-1.5 ka cal. BP development of a delta-mouth sedimentary system recognised in the southern Venice Lagoon. The results show that major avulsive events in the upstream tracts of the Po and Adige Rivers forced the migration of delta lobes. The delta system in the southern Venice Lagoon was fed by the Saline-Cona Po branch from about 4-3 ka cal. BP. This implies that the Po delta extended as far as 30 km north of the present-day river position. In this time frame, the Adige did not directly reach the sea, as it was a tributary of the Po at Agna. The northernmost lobe of the Po delta was thus fed by the sedimentary input of both the Po and Adige. The subsequent deactivation of the Saline-Cona Po branch through avulsion just upstream of Rovigo, around 3 ka cal. BP, led to a southwards shift of the Po delta system. The Adige still flowed through the Conselve ridge and kept its mouth in the same area. From 3 ka cal. BP to Roman times, the river constructed its own delta in the southern Venice Lagoon, prograding on the previous northern Po delta lobe. The Adige avulsion at Bonavigo during the early Middle Ages led to the abandonment of the Montagnana-Este-Conselve course long the southern foot of the Euganean Hills. As a consequence, the delta in the southern Venice Lagoon was also definitely abandoned and the Adige River started to construct another delta in its present-day position, about 15 km further to the south.

Stratigraphic evidence of a Middle Pleistocene climate‐driven flexural uplift in the Alps

This interdisciplinary study on the subsurface stratigraphy of the Po Plain (northern Italy) brings new evidence in support of a climate‐driven erosional unloading of the Alps since the Middle Pleistocene. A newly acquired, high‐resolution seismic profile and a critical review of industrial seismic lines were integrated with sedimentologic observations on four magnetostratigraphically dated continental cores to reconstruct a three‐sequence evolution of the Pleistocene clastic infill in the northern Po basin. During the first sequence (PS1; ∼1.4–0.87 Ma), characterized by sedimentation rates of ∼34 cm/kyr outpacing regional subsidence, meandering river systems prograded over the basin passing downstream to a cyclothemic shelfal succession. The second sequence (PS2; ∼0.87–0.45 Ma), heralded by a regional unconformity (R surface) correlated to the onset of the major Pleistocene glaciations, was characterized by widespread continental sedimentation of generally distal braidplain. The third sequence (PS3; ∼0.45 Ma to present), marked at the base by another regional unconformity (Y surface), is characterized by proximal braided fluvial deposition under combined conditions of confinement, erosion, and bypass. We interpret the PS3 sequence as deposited under the effects of a flexural uplift of the northern Po Plain during the Middle Pleistocene starting at ∼0.45 Ma, in response to the long‐term erosional unloading of the Alps triggered by the waxing and waning of Alpine glaciers since the late Early Pleistocene global cooling (∼0.9 Ma). According to our modeling, erosion on a relatively limited area of the Alpine mountain chain, ranging from 1.3 to 1.7 mm/yr in the axial sector to 0.1–0.3 mm/yr at the margins, has been able to trigger rock uplift over a wider area including the proximal peripheral basins.

Interstellar polarization at high galactic latitudes from distant stars

We present a detailed map of interstellar polarization for the South Galactic Pole (b 0.011 at the NGP and E(B −V) > 0.016 at the SGP (Appenzeller 1975). However, his polarization data in the SGP zone cover only the area 45 ◦ b > −80 ◦ . Our first results for the South Galactic Pole (b 0.4%) were detected. We also found that the directions of the observed interstellar polariza- tion are very well aligned with the Galactic latitude l ≈ 80 ◦ . However, the polarization map of the southern circumpolar area at that time was far from complete: less than 30 percent of the 20 ◦ zone around the South Galactic Pole had been studied. In 2001−2003 we have continued our measurements and cov- ered the previously unstudied area. This gives us a detailed pic- ture of the interstellar polarization around the SGP and allows us to make a straightforward comparison with the northern po- lar direction.

Collection and preliminary evaluation of native turfgrass accessions in Italy

Despite a raising interest on turfs in Italy, all theavailable varieties of this kind in the Country are of foreign origin, and areoften poorly adapted to the prevailing climatic conditions. This prompted tobegin a collection activity of indigenous turfgrass species, with the ultimategoal of identifying promising materials for future breeding based on localgenetic resources. The collection was carried out in three areas of Italy, viz.the northern Po Plain, the coastal region of Liguria, and the island of Sardiniathat are characterised, respectively, by subcontinental, warm temperate, andtypical Mediterranean climate. Altogether, 141 sites were visited, yielding 226accessions belonging to eight species of potential interest for turfs:Poa pratensis, Poa trivialis,Festuca rubra, Festuca arundinacea,Lolium perenne, Agrostis stolonifera,Agrostis tenuis, and Cynodon dactylon,this last being a warm-season grass. Poa pratensis andCynodon dactylon were mostly collected in northern Italyand Sardinia, respectively, whereas Festuca arundinacea andLolium perenne were rather ubiquitous. The collection sitesranged from 0 to 1040 m asl, but sites over 750 m wereonly visited in the inner part of Sardinia. All the accessions, collected aswhole plants, were transplanted at Lodi, northern Italy, where they are beingevaluated. Their preliminary evaluation for traits of importance for turf use,such as sward colour and overall quality, highlighted the great variation andthe occurrence of interesting accessions in all species. Other characters wererecorded, bearing specific importance in individual species, and in all casespromising accessions were identified. The germplasm of Festucarubra, Festuca arundinacea, and Loliumperenne proved highly infected by endophytic (symbiotic) fungi of thegenus Neotyphodium.

Study of local scaling in the stable atmospheric boundary layer for the evaluation of turbulence parameters

A renewed interest in the dynamic and thermal structure of the atmospheric boundary layer (ABL) has recently revived, due to the contribution that this layer can provide to the improvement of skill of weather prediction and climate simulation in the most advanced general circulation models. The attention is particularly focused on non-stationary and non-homogeneous turbulent structures of this transition layer, for which many parametrization schemes, based on local-and non-local-closure assumptions, have been proposed. However, also stationary, non-homogeneous, continous-turbulence conditions can give rise to some complication in the ABL parametrization when air stability becomes stronger and stronger. In this situation, the governing scales of the classical non-local Monin-Obukhov similarity theory are no more representative, and new local scales must be derived from local forcings of the flux. This paper summarizes a few relevant points of the local-similarity theory and shows the results of a local-scaling analysis obtained by observation data of wind and temperature profiles in the ABL in the northern Po Valley

Food habits and trophic relationships of small mammals in six habitats of the northern Po plain (Italy)

Le regime alimentaire de sept especes de rongeurs et d'insectivores a ete etudie par methode quantitative. Le materiel d'origine animale constitue la majorite de la nourriture pour les insectivores, mais avec des importantes portions de plantes et de graines. Parmi les rongeurs, Clethrionomys glareolus et Mus domesticus se nourrissent surtout de parties de plantes vertes, tandis que le regime alimentaire d'Apodemus sylvaticus est domine par les graines. Les differences liees a l'habitat sont generalement reduite chez les rongeurs, et legerement plus importantes chez les insectivores. Les variations saisonnieres du regime alimentaire de Clethrionomys glareolus et Apodemus sylvaticus sont differentes dans le centre et dans le nord de l'Europe

Composition and Longshore Dispersal of Sands from the Po and Adige Rivers Since the Pre-Etruscan Age

ABSTRACT The sands presently carried by the Po River differ from those of the Adige River mainly in the content of dolomite and of fragments of acidic volcanic rocks, and to a lesser degree in the content of some heavy mineral species; such differences individuate two petrographic provinces. Compositional data of samples from paleoriver beds and bars reveal that the same differences were present during past times. Complex admixtures of sands from the two petrographic provinces are often observed in sands from beach ridges, whose shape also depends on eolian activity and on the consequent formation of dunes. The beach ridges are the product of an evolution from protruding deltaic bodies to a marked regularity of the coastline. Such modifications are mainly due to marine erosional processes, which are of greatest relative importance during periods of decreased fluvial discharge. Under these conditions the river-supplied sands are redistributed, with resultant admixture of sands from the two petrographic provinces. The sands from deltaic channel-mouth bars have compositions that become increasingly uniprovincial from early to late depositional stages. These bars form at times of increased fluvial deposition, when the rivers build prominent deltas that modify a previously straight coastline. Under such conditions, longshore transport of sands gradually become less important so that mixing of sediments derived from the different provenances gradually becomes negligible. Since pre-Etruscan times, the sands carried by the Adige River were transported longshore towards the south and were mixed with sands from the Po River moving north. The convergence zone between the two provinces was usually controlled by whichever distributary of the Po had the higher discharge among northern Po branches. That distributary would produce a marked deltaic body that modified the coastline until the southward drift of the Adige sands ceased. By comparing compositional data with the historical geomorphic evolution of the system, the most active mouths of the Po in terms of discharge have been identified from the Etruscan age to the present.

Etude geologique de la rive occidentale du lac de Garde de Bogliaco a Salo et des regions situees a l'est de Brescia (Alpes meridionales, province de Brescia, Italie)

Abstract The stratigraphic section exposed on the west bank of Garda lake and the northern Po plain, northern Italy, represents continuous marine sedimentation from the lower Jurassic to the Lutetian (Eocene), followed by isolated outcrops of Oligocene to Pliocene deposits as young as Calabrian. The two regions studied belong to the Judicarian tectonic phase which produced NNE-SSW oriented structures. The Mesozoic-Tertiary series is represented by varying facies, from thin neritic limestones in the lower Lias to conglomerates, sands, and clays in the Pliocene. These deposits occupy the east flank of the Lombardy trough and were influenced by the Tridentine fold system to the east. The deposits suggest that the area is a transition zone between the Lombardy to the west and the Tridentine to the east.