Apennine Rivers Research Articles

Better Safe Than Sorry: A Model to Assess Anthropic Impacts on a River System in Order to Take Care of the Landscape

The need to find a trade-off between protecting water-related ecosystems and increasing safe water-use for human society is recognized in the 2030 Agenda of the European Union. We assess the ecological status of a riverine system in order to mitigate human impacts, considering its importance for supplying drinking water to more than 4 million users in Rome. We used an integrated approach, analyzing animal and plant communities at riverbanks and the riverbed. A macrobenthos analysis revealed a well-structured community with a good ecology for all sampling stations. The highest value was found immediately upstream and downstream of the springs collection system, while the lowest richness value was where the river collects urban wastewater. A floristic inventory showed Hemicryptophytes composing almost 45% of all species, and prevalence of Euroasiatic (35%) and Orophilous (34%) chorotypes. A positive correlation between riverbed vegetation and the quality of the benthic community was revealed, while tree height seems to have a negative trend. Our data suggest a river stretch affected by resurgence and water abstraction did not highlight irreversible alterations to the landscape. Indeed, the composition of vegetation and correlated animal communities mirrored a clinal gradient expected for an Apennine river system. Our study has the potential to improve the approach used to monitor the impacts of humans on freshwater ecosystems, aiming at preserving the integrity of the water-related landscape.

On depositional processes governing along‐strike facies variations of fine‐grained deposits: Unlocking the Little Ice Age subaqueous clinothems on the Adriatic shelf

ABSTRACTDepositional processes recorded by shelf deposits may vary widely along‐strike, depending largely on the mode of delivery and deposition of sediments to the basin. In fine‐grained systems in particular, depositional processes are difficult to reconstruct with standard facies analysis of sediment cores due to the ostensibly featureless and homogenous appearance of muds. In this study, sedimentological, palaeontological, geochemical, and oceanographic data were combined in a detailed characterization of depositional conditions via sedimentary structures, type of organic matter, trace‐metal geochemistry, and benthic fauna assemblages (foraminifera and ostracods) along the 600 km long shelf delta clinothems of the West Adriatic shelf (Italy). Processes inferred from sedimentary facies and micro‐structures were then considered in the context of the modern Adriatic oceanographic regime. Specific attention was given to the Little Ice Age stratigraphic unit (1500–1850 ce), which contains a continuum of genetically related fine‐grained strata. The Little Ice Age deposit offers the opportunity to examine a source‐to‐sink system with the high resolution typical of modern analogues, at a time interval when Apennine rivers were not yet hydraulically engineered with man‐made sediment traps along their trunks. Individual beds within the Little Ice Age muddy prodelta form hectometre to kilometre‐wide bedsets that reflect the interplay between energetic meteo‐ocean conditions (storm‐dominated beds), flood supply (river‐dominated beds or hyperpycnites) and along‐shelf bottom‐current dispersion (drift‐dominated beds). The multidisciplinary approach applied at different scales of observations helped in understanding sediment provenance and the relative timing of sediment transport before final burial that strongly promoted organic matter oxygen exposure and the loss of carbon by microbial degradation. Overall, the distinctive depositional processes that acted in concert along the prodelta slope produced a subtle lateral heterogeneity of preserved sedimentary structures, faunal associations, and organic matter composition in a laterally‐continuous lithostratigraphic unit deposited at centennial scale. These findings have implications on the forcing conditions that ultimately control the location and nature of fine‐grained beds in both modern and ancient, mud‐dominated depositional systems.

Mapping Apennines river paths along different hydrological conditions from satellite images: A description of the method and potential applications

AbstractClimate change is producing large impacts on rivers, amplifying hydrological extremes. Prolonged drought periods result in dramatic stress for river biota and associated processes due to low discharge, reducing the interactions between rivers and their lateral environments or leading to hydrological intermittency. New quantitative methods are needed, to correlate discharge with the available riverine habitats. In this work we have mapped the wet surface and paths of two stretches of the Taro and Trebbia Apennine rivers, analyzing satellite images from periods with contrasting discharge. The considered stretches are critical due to different human pressures (large water withdrawals for agriculture and industrial use) and are particularly vulnerable to further, climate‐driven discharge reductions. The produced images offer multiple possibilities to extract qualitative and quantitative information at the whole stretch scales, including habitat reduction along with decreasing discharge, threshold discharge limiting lateral interactions, or the evaluation of longitudinal river continuity. We discuss the limitation and the potentialities of the method and the maps produced in terms of possible application in the field of river geomorphology, ecology, the definition of ecological river flow, risk assessment, and river management.

No post-drought recovery of the macroinvertebrate community after five months upon rewetting of an irregularly intermittent Apennine River (Aterno River)

The combined effects of global changes and increasing water demand for human use are the main drivers of the increasing intermittence of most watercourses. The disruption of lateral, longitudinal and vertical connectivity during the dry phase in newly intermittent rivers may have dramatic effects on freshwater biota, ecosystem structure and processes and may extend its influence also after several months from the return of superficial flow. A few studies have systematically documented the dynamics of post-drought recovery of freshwater communities. In this paper we assessed the temporal dynamics of benthic invertebrate's recovery starting from the first day after superficial flow resumption and for the successive five months. We demonstrated that the recolonization process of rewetted substrata was very low and partial, and after five months from the return of superficial flow the richness and abundance of post-drought re-colonizers were markedly lower if compared with the pre-drought community and with that of a near upstream perennial site. In this context, upstream drift, “seedbanks” and hyporheic refugia would be of minor importance and the observed recolonization pattern may be mainly explained by the aerial dispersal from downstream perennial reaches of tolerant and generalist taxa. Therefore, former perennial Apennine rivers may be profoundly affected by modifications of the natural flow regime. Increasing intermittence of these watercourses may determine drastic changes in community structure and composition, with species loss and species substitution. In addition, the high post-drought functional turnover may have negative effects on key ecosystem processes as leaf-litter breakdown and primary production.

Study of antibiotic resistance in freshwater ecosystems with low anthropogenic impact

This study aimed to investigate the bacterial diversity and the background level of antibiotic resistance in two freshwater ecosystems with low anthropogenic impact in order to evaluate the presence of natural antimicrobial resistance in these areas and its potential to spread downstream. Water samples from a pre-Alpine and an Apennine river (Variola and Tiber, respectively) were collected in three different sampling campaigns and bacterial diversity was assessed by 16S sequencing, while the presence of bacteria resistant to five antibiotics was screened using a culturable approach.Overall bacterial load was higher in the Tiber River compared with the Variola River. Furthermore, the study revealed the presence of resistant bacteria, especially the Tiber River showed, for each sampling, the presence of resistance to all antibiotics tested, while for the Variola River, the detected resistance was variable, comprising two or more antibiotics. Screening of two resistance genes on a total of one hundred eighteen bacterial isolates from the two rivers showed that blaTEM, conferring resistance to β-lactam antibiotics, was dominant and present in ~58 % of isolates compared to only ~9 % for mefA/E conferring resistance to macrolides. Moreover, β-lactam resistance was detected in various isolates showing also resistance to additional antibiotics such as macrolides, aminoglycosides and tetracyclines. These observations would suggest the presence of co-resistant bacteria even in non-anthropogenic environments and this resistance may spread from the environment to humans and/or animals.

Effects of antecedent drying events on structure, composition and functional traits of invertebrate assemblages and leaf‐litter breakdown in a former perennial river of Central Apennines (Aterno River, Abruzzo, Central Italy)

AbstractBecause of global change and increasing anthropogenic pressures, non‐perennial rivers and streams are predicted to drastically increase in the European‐Mediterranean region. Some river basins already subject to reduced levels of available superficial flow may present a further reduction, with a significant increase in intermittence phenomena and complete drought of former perennial rivers. In this context, a sound knowledge of the ecological effects of increasing drying events on these watercourses may help to better predict impacts of the altered flow regime on structure and functions of freshwater ecosystems. In this paper, we assessed the long‐term response of invertebrate assemblages and ecosystems processes to antecedent drying events (drying memory) in a Central Apennine river (Italy). We demonstrated that compared to the perennial reach, the 7‐km downstream intermittent site, after more than 1 year from a complete superficial flow resumption, still conserved the ‘memory’ of past disturbance with marked differences in structure, composition and functional traits of assemblages which, in turn, negatively influenced the leaf‐litter breakdown process. Despite total abundance and taxa richness were on average higher at the intermittent site, antecedent droughts determined a decline of shredders and scrapers and an increase of collectors. In addition, some more sensible, semivoltine and rheophile taxa were replaced by generalist, multivoltine and more resistant taxa. Our findings confirm and extend the ‘drying memory’ hypothesis and suggest that irregular drying events in former perennial Apennine rivers may have dramatic long‐term effects on both structure and functions of lotic ecosystems.

A multiple regression model to estimate the suspended sediment yield in Italian Apennine rivers by means of geomorphometric parameters

A new statistical prediction model, aimed to assess the mean annual suspended sediment yield (SY) in ungauged rivers of Italian Apennines, is here presented. A multiple linear regression equation was obtained by the stepwise technique investigating the relationships between a series of hydro-geomorphometric variables and sediment yield data from 41 river basins located along peninsular Italy and Sicily. The model variables were computed from hydrological data records and from vector river network lines and drainage divides derived from official maps and DEM. The analysis revealed a large variance in the observed sediment yield data. Nonetheless, an optimal result in terms of model significance and efficiency (r2adj = 0.91 at p < 0.05 significance level; Nash–Sutcliffe model efficiency NSE = 0.855; Willmott’s indexes of performance: d = 0.965; d1 = 0.862; dr = 0.862) was finally achieved. According to stepwise regression, the catchment relief and perimeter, together with the topological organization of stream network, the bedrock erodibility and the stream gradient, expressed by specific parameters, appeared as determinant features for SY prediction in the catchments here investigated. The developed model could be helpful to practitioners and scholars for rapid assessments of SY at any point of the river network in the geographic area here concerned. However, the same technique can be utilized wherever in the world since the statistical method itself allows to recognize the number and type of parameters to be used in a given geographic area, on the basis of their local significance.

Sediment dispersal pathways in the Po coastal plain since the Last Glacial Maximum: Provenance signals of autogenic and eustatic forcing

AbstractWe examined downstream trends in sediment composition within the modern Po River system and defined provenance changes within a selected sector of the Upper Pleistocene to Holocene coastal plain in response to paleogeographic reorganisation during the last glacial‐interglacial cycle. Sediment composition of the Upper Pleistocene to Holocene alluvial and coastal plain succession overlaps with the modern petrofacies, suggesting that ancient fluvial sand was sourced from a dynamic river system attributable to a distal paleo‐Po with episodic sediment input from South Alpine and Apennine rivers. In the wave‐dominated estuarine depositional system developed under transgressive conditions, Po‐derived detritus mixed in the coastal system with sediment fed by Central/Eastern Alpine rivers, which was redistributed southwards by alongshore currents. A similar, mixed composition of late Holocene highstand depositional systems reflects the progradation of Po delta lobes (similar in composition to Po River sands) and adjacent strandplains (typified by sediment mixing due to alongshore transport). Compositional variability across the main stratigraphic surfaces suggests that autogenic processes (e.g. marine reworking, sedimentary mixing, delta switching/abandonment) in turn influenced by glacioeustasy, controlled the development of the transgressive and highstand Po Plain succession. This study clarifies the effect of fluvial‐marine interaction during the Holocene evolution of the Po coastal system and can be used as a model to interpret the evolution of many mixed‐delta types and Quaternary successions that shows alternating river‐flood and wave‐dominated deposits.

Ecology and conservation of the Mediterranean trout in the central Apennines (Italy)

The Mediterranean brown trout (Salmo trutta complex) is one of the freshwater fish species complex at greater risk of extinction in the Mediterranean area. The introduction of alien invasive species and their interaction with the native fauna represent some of the major threats to the survival of this species. Currently, the genetic variability of the Mediterranean trout (Salmo trutta complex) is being compromised by the introgressive hybridization with the Atlantic trout (Salmo trutta Linnaeus, 1758). Therefore, it is necessary to gain further knowledge on genetic and demographic characteristics of Mediterranean trout populations, that, combined with environmental and angling data, will allow to undertake sound conservation strategies. The aims of the present study were to analyze: i) the demographic characteristics of the Mediterranean trout in seven central Apennine river basins where native populations are threatened by stocking with the domestic trout of north Atlantic origin; ii) the influence of both environmental parameters and different fishery management strategies on the status of native trout populations. The project focuses on 14 sites included in the Natura 2000 EU wide network of nature protection areas, established under the 1992 Habitat Directive. A total of 25 watercourses were investigated for a total of 32 sampling sites. A census of the fish fauna was carried out by electrofishing at each sampling location. Fish and environmental data were collected in spring and autumn 2014. The results obtained in the present research allowed us to detect the presence of three residual Mediterranean trout populations with a high degree of genetic integrity in the study area. The native trout populations were characterized by higher abundances and higher adult density values. Well-structured native populations with higher legal-size specimens density and poor body conditions in terms of relative weight were observed in the no-fishing areas, probably due to the presence of intraspecific competition phenomena. The environmental analysis confirmed the key role played by the geological characteristics of the central Apennines in shaping the introgression levels observed in the wild trout populations, while the recovery of the water quality appears decisive in the development of management strategies aimed at their conservation.

Spatial pattern analysis of Ni concentration in topsoils in the Campania Region (Italy)

The objective of this study is to demonstrate the combined use of point pattern, multifractal and digital image processing analysis in order to recognise and characterise spatial patterns of Ni concentration in topsoil in the Campania Region (Italy). After an exploring univariate statistical analysis, spatial clusters and outliers were revealed by Moran-I autocorrelation among the original measurement points. The linear and accurate Triangular Irregular Network (TIN) interpolation of Ni concentrations fitted at 3663 sample points was used. Successive moving average smoothing was applied to generalise the TIN model and to suppress small irregularities. The resulting raster map was the subject of multifractal analysis to classify the TIN-based Ni raster concentration map and to define Ni-baseline values. Digital Image Processing including lineament density and spatial variability index calculation was performed not only on the TIN-based total Ni raster map but also on its baseline map to recognise spatial patterns. The Ni-baseline map was given particular attention because the spatial distribution and variance in this map are assumed to be related to different geogenic processes.The highest spatial variability zones of total Ni concentrations are located in Campi Flegrei and around Napoli where low Ni values and spatial outliers are clustered. The highest variability zones can be found in topsoils over volcanoclastic rocks and they are related to urbanised and agricultural land use areas. The lowest variability zones coincide with the Eocene-Miocene argillaceous sediments of the Apennine Mts where the highest Ni values were measured.The highest spatial variability in the Ni-baseline map is in a NW-SE zone following the carbonate outcrops of the Apennine Mts (e.g. Mt. Alburni, Mt. Picentini). Another interesting NW-SE trending moderate to high variability zone was also identified following the alluvial plains of the Apennine's rivers. The Apennine's rivers seem to have played a crucial role in the redistribution of Ni through sediment transport processes resulting in higher spatial variability of Ni in the studied soils. The lowest variability zone is located south of Campi Flegrei and Napoli and it occupies the vast area of the Campanian Plain.

Reconstructing Last Glacial Maximum and Younger Dryas paleolandscapes through subsurface paleosol stratigraphy: An example from the Po coastal plain, Italy

Paleosols are commonly used to reconstruct ancient landscapes and past environmental conditions. Through identification and subsurface mapping of two pedogenically modified surfaces formed at the onset of the Last Glacial Maximum (LGM) and during the Younger Dryas (YD) cold event, respectively, and based on their lateral correlation with coeval channel-belt sand bodies, we assessed the geomorphic processes affecting the Po coastal plain during the Late Pleistocene (30–11.5calky BP). The 3D-reconstruction of the LGM and YD paleosurfaces provides insight into the paleolandscapes that developed in the Po alluvial plain at the transitions between warm and cold climate periods. The LGM paleosol records a stratigraphic hiatus of approximately 5kyr (29–24calky BP), whereas the development of the YD paleosol was associated with a climatic episode of significantly shorter duration. Both paleosols, dissected by Apennine rivers flowing from the south, dip towards the north-east, where they are replaced by fluvial channel belts fed by the Po River. The LGM channel-belt sand body reflects the protracted lateral migration of the Po River at the onset of the glacial maximum. It is wider (>24km) and thicker (~15m) of the fluvial sand body formed during the YD. The northern margin of LGM Po channel-belt deposits was not encountered in the study area. In contrast, a spatially restricted paleosol, identified in the north at the same elevation as the southern plateau, may represent local expression of the Alpine interfluve during the YD event. This study highlights how 3D-mapping of regionally extensive, weakly developed paleosols can be used to assess the geomorphic response of an alluvial system to rapid climate change.

Occurrence and distribution of six selected endocrine disrupting compounds in surface- and groundwaters of the Romagna area (North Italy).

Endocrine disrupting compounds (EDCs) are a wide group of contaminants of emerging concern known to be harmful for organisms. The aim of the study was to assess the occurrence and distribution of six EDCs (estrone-E1, ß-estradiol-E2, 17α-ethinylestradiol-EE2, bisphenol A-BPA, perfluooctanoic acid-PFOA, perfluorooctane sulfonate-PFOS) in the Apenninic rivers and groundwaters of the Romagna area (North of Italy). Groundwaters were unaffected by EDC contamination, while all classes of compounds were detected at concentrations above the method quantification limit (MQL) in the majority of the river bodies. In detail, PFOA and PFOS concentrations varied between <MQL and 17.7ng/l (PFOA) and between <MQL and 5.5ng/l (PFOS), and their occurrence in the aquatic compartment was related to the discharge of wastewater treatment plant effluents. Concerning estrogens, EE2 was below the MQL in all samples, whereas E1 and E2 reached concentrations up to 39.7ng/l (E2) and 28ng/l (E1) in surface waters. The highest estrogen values were registered in those areas where livestock and farming are the main activities, indicating a close relation between these activities and estrogen release into the aquatic compartment. BPA (<MQL-171.3ng/l) distribution in river waters did not show any correlation with a specific anthropic activity; a mixture of sources of contamination (e.g., industries of food packaging and plastic production) is rather responsible for its detection in river bodies. Overall, the northern part of the Romagna area showed a higher contamination by EDCs, in contrast with the southern part, which was almost unaffected by this kind of microcontamination.

Sediment composition, provenance, and Holocene paleoenvironmental evolution of the Southern Po River coastal plain (Italy)

Geochemistry, sediment provenance, and the Holocene paleoenvironmental evolution of the Southern Po River coastal plain (Italy) were examined based on the geochemical analysis of 279 sediment samples from 35 cores. The Holocene succession is subdivided into four major facies associations: back‐barrier, transgressive barrier, shallow‐marine, and beach‐ridge deposits. Bulk chemical composition shows remarkable differences between facies associations, and the poly‐modal behavior in the related frequency curves suggests distinct sources of sediment. Using MgO and Ni as geochemical tracers, changes in sediment provenance were assessed with the aim to reconstruct the Holocene paleoenvironmental evolution of the area. The Po River and the Apenninic rivers represented the main sources of sediment during the early stages of transgression and highstand sea‐level conditions, whereas transgressive barrier and early shallow‐marine facies associations exhibit a clear North Adriatic river (eastern Alpine) provenance. The Holocene paleoenvironmental evolution of the study area, between about 10 ky and the present, indicates the presence of a bypass zone in front of the Po River mouth between 9 and 6 ky BP. At that time, sediment supplied by the North Adriatic rivers was transported southward by the longshore drift, bypassed the weak Po River influx and accumulated close to the Apennines. Comparison between Holocene facies associations and current back‐barrier and shallow‐marine sediments confirms that the present‐day basin circulation is similar to the one that acted during the last episode of sea‐level rise.

The influence of flow‐through saline gravel pit lakes on the hydrologic budget and hydrochemistry of a Mediterranean drainage basin

AbstractFlow‐through brackish gravel pit lakes near the Adriatic Coast of Emilia Romagna (Italy) in the Mediterranean have a large influence on the hydrologic budget of the watershed. Strong evaporation in combination with intense drainage of the low lying basins enhances groundwater inflow into the lake. Precipitation falling on the lakes is mixed with brackish/saline lake water causing the loss of freshwater. The gravel pit lakes are characterized by a high salinity (TDS = 4.6–12.3 g L−1) and high pH (8.5). Stable isotope data show that gravel pit lake water is fed by groundwater which is a mix of Apennine River water and (Holocene) Adriatic Seawater, subsequently enriched by evaporation. The slope of the local evaporation line is 5.4. Conservative tracer and water budget modeling shows that the final Cl concentration depends strongly on the ratio of evaporation to total inflow. Increasing drainage to compensate for sea level rise, subsidence or intense precipitation would enhance ground water flow into the lake and decrease Cl concentration while increasing evaporation would increase Cl concentration. Groundwater rich in dissolved trace elements flows into the gravel pit lakes that contains water with a higher pH and dissolved oxygen. Pit lake water remains enriched in some elements (e.g., Ba, Mo, Sb) and depleted in others (e.g., Fe, Ca, Zn, SO4) with respect to groundwater composition. The gravel pit lakes show limited eutrophication but the water quality should be monitored for trace elements (e.g., As) if they are to be used for recreational purposes.

Multiple X‐ray approaches to discriminate the origin of liquefied sand erupted during the 2012 Emilia Romagna earthquake

Geochemical, mineralogical and sedimentological analyses were carried out on sands erupted from sand volcanoes and soil cracks during the 2012 Emilia earthquakes with the aim of determining their origin and depth of provenance in a complex stratigraphic plain generated by different fluvial contributions. Geochemical, mineralogical and sedimentological analyses were performed by wavelength dispersive X‐ray fluorescence, X‐ray powder diffraction and Sedigraph and Settling tube, respectively.Distinct textural features, as well as Ni/MgO and Cr/Al2O3 ratios, allow discriminating two populations: an A‐area located close to San Carlo village and a B‐area nearby Scortichino village. Sediments from A‐area show chemical and mineralogical characteristics well comparable with those of the sediments derived from the Apennine rivers, whereas sands from B‐area have strong similarities with the sediments from the Po river.In the earthquake crater area most of the liquefaction phenomena were related to superficial sandy deposits (fluvial ridges, paleochannels and crevasse splays) generated by Apennine rivers. The Po river sediments in the B‐area derive from a layer at a depth at which liquefaction phenomena were excluded, because of the greater lithostatic load. These sediments thus shed a new light on the mechanisms that may induce liquefaction during an earthquake or even without a seismic triggering.It is suggested that a gas phase (mainly methane), which is commonly found below the Po plain, could have been dissolved in the water, near to the saturation threshold or already exsolved, increasing the interstitial overpressure and facilitating the liquefaction and the eruption of the sandy sediments. Copyright © 2015 John Wiley &amp; Sons, Ltd.

Life+ Trout Project (LIFE12 NAT/IT/0000940) for the recovery and conservation of Mediterranean trout (Salmo trutta complex) in the central Apennines (Italy).

Life+ Trout Project (LIFE12 NAT/IT/0000940) for the recovery and conservation of Mediterranean trout (Salmo trutta complex) in the central Apennines (Italy).

Sedimentological, biogeochemical and mineralogical facies of Northern and Central Western Adriatic Sea

The aim of this work was to identify sedimentary facies, i.e. facies having similar biogeochemical, mineralogical and sedimentological properties, in present and recent fine sediments of the Northern and Central Adriatic Sea with their spatial and temporal variations. Further aims were to identify the transportation, dispersion and sedimentation processes and provenance areas of sediments belonging to the facies. A Q-mode factor analysis of mineralogical, granulometric, geochemical (major and trace elements) and biochemical (organic carbon and total nitrogen) properties of surficial and sub-surficial sediments sampled in the PRISMA 1 Project has been used to identify the sedimentary facies. On the whole, four facies were identified: 1) Padanic Facies, made up of fine siliciclastic sediments which reach the Adriatic Sea mainly from the Po River and are distributed by the Adriatic hydrodynamic in a parallel belt off the Italian coast. Southward, this facies gradually mixes with sediments from the Apennine rivers and with biogenic autochthonous particulate; 2) Dolomitic Facies, made up of dolomitic sediments coming from the eastern Alps. This facies is predominant north of the Po River outfalls and it mixes with Padanic Facies sediments in front of the Po River delta; 3) Mn-carbonate Facies, made up of very fine sediments, rich in coccolithophores and secondary Mn-oxy-hydroxides resulting from the reworking of surficial fine sediments in shallow areas and subsequent deposition in deeper areas; 4) Residual Facies, made up of coarse siliciclastic sediments and heavy minerals resulting from the action of waves and coastal currents; this facies is present mainly in inshore areas.The zoning of the facies, resulting from this study, will make possible the identification, through further investigation, on a greater scale, of more accurate facies borders and the recognition of sub-facies, resulting from secondary or weaker biogeochemical processes.

The use of particle density in sedimentary provenance studies: the superficial sediment of Po Plain (Italy) case study

In recent years, several approaches for the identification of the provenance of the sediments have been developed. In particular, geochemical, petrographic and mineralogical analyses were applied to the sediments of the Po Plain in order to discriminate the alluvial sediments of the Po River from those coming from Apennine rivers. In this work, we propose an innovative technique based on the measurement of density for the study of the Po Plain alluvial sediments. This study is based on the determination of major and trace elements, particle density and mineralogical composition of 53 superficial sediments. All the data were processed using multivariate statistics. The comparison between density, geochemistry, and granulometry of the Po River and Reno River (the most important Apennine river) samples shows how the densities strictly depend on the chemical-mineralogical composition and grain size of the sediments and, consequently, on the type of hydrographic basin of their respective river. On this basis it can be discriminated the provenance of two different types of alluvial sediments with sufficient precision, determining the density of the unconsolidated alluvial material.

Provenance of surface sediments along the southeastern Adriatic coast off Italy: An overview

Multi-proxy studies are necessary to understand sediment composition and related provenance on continental shelfs. Here it is shown that the spatial distribution of geochemical composition and grain size for surface sediments along the southeastern Italian coast is related to provenance and mechanisms influencing sediment pathways. A northern Adriatic/Italian provenance can be distinguished from a southern Apennine river source. This is done independent of grain size using the element ratios Ce/Ni and Zr/Cr. Furthermore, the origin of organic matter is determined using bulk carbon isotopes and the C/N ratio. Integrating these results with those from complementary studies on δ18O and δ13C of Globigerinoides ruber (white), the BIT index, stable isotopes of plant waxes and dinoflagellate cyst distribution from the same set of samples reveals that:•Sediments from the northwestern Adriatic are transported as far southward as the Gallipoli shelf (eastern Gulf of Taranto) by the Western Adriatic Current (WAC)•Along the WAC, there is a consistent southward decrease in Po river/northern Apennines provenance and a concomitant decrease in terrestrial (soil) organic matter (OM), whereas the percentage of marine OM increases.•The provenance for Gallipoli shelf sediments is for ∼80% attributed to Po River/northern Apennines sources and for ∼20% to southern Italian sources.•OM in the eastern Gulf of Taranto contains more marine OM than other areas within the WAC, whereas OM and sediments from the western part of the Gulf of Taranto have a more local, riverine provenance.

Distribution and stable isotopes of plant wax derived n-alkanes in lacustrine, fluvial and marine surface sediments along an Eastern Italian transect and their potential to reconstruct the hydrological cycle

Reconstructing terrestrial water budgets is of prime importance for understanding past climate and environment. To shed more light on how plant-wax derived n-alkanes may be used for this purpose we investigated the distribution and stable isotopic compositions of hydrogen (δD) and carbon (δ13C) of plant-wax derived n-C29 and -C31 alkanes in terrestrial, coastal and offshore surface sediments in relation to hydrology along a NW–SE transect east of the Italian Apennines from the Po River to the Eastern Gulf of Taranto. The plant wax average chain length increases southward and may relate to increasing temperature and/or aridity. The plant wax δD of the terrestrial and coastal samples also increases southward and mainly reflects changes in the δD of precipitation. The δ13C of plant waxes is primarily interpreted in terms of C3 vegetation changes rather than varying contributions by C4 plants. The plant wax δ13C–δD composition of the Po River and Apennine rivers differs considerably from that in southern Italy, and suggests a mainly southern source for plant waxes in marine sediments of the Gulf of Taranto. This calibration provides a basis for the reconstruction of past changes in the Italian water balance and n-alkane source areas.