Vulnerability to contamination by phosphorus in a zero-order basin with a high density of pigs and a history of slurry addition: extrapolation of an index

The application of phosphorus (P)-index methodology to assess the risk of water pollution from agriculture in river basins usually takes time and expends a great amount of resources. This study adapted the P-index methodology using digital mapping of key basin risk criteria for P loss in reference areas to evaluate the wider vulnerability to P loss in a zero-order basin with an intense concentration of pigs and with a history of pig slurry additions to the soil. The P content of eleven reference areas, where ten areas have received various applications of pig slurry and one area has no history of addition, was extrapolated to a zero-order basin using principal component analysis and analysis of hierarchical groupings. Estimated loss of soil and the distance between the P source and the watercourse were mapped using satellite images and in situ evaluations. The methodology of extrapolating was well correlated with a survey of P concentrations in land runoff and provides the potential to improve land management of those areas that are most vulnerable. Principal component analysis and hierarchical clustering analysis proved to be useful tools for the separation of areas with different slurry application times. Our results suggest that the P loss risk could be reduced through the adoption of soil conservation techniques such as reduced-tillage incorporating slurry and crop residue management to provide adequate soil protection, reduce the impact of raindrops and reduce erosion risk and transport of chemical pollutants to water bodies.     

Physical contact interactions with scleractinian corals in hard substrate communities

Shallow reefs are among the most diverse ecosystems, and their substrate is densely occupied by sessile organisms that frequently contact physically and interact mutually. Nevertheless, the relative importance of species abundance in shaping physical contacts in these ecosystems remains largely unknown. The aim of this study was to evaluate physical contact interactions, by using tools derived from the complex network theory, between hard corals and other benthic organisms in four areas along the Brazilian coast comprising coral reefs and rocky shores with different physical and biotic structures. It was also investigated whether interactions with corals occurred as expected by the abundance of the benthic organisms in each area, and whether corals belonging to families known as more aggressive interacted less with other organisms. In all areas, the abundance of both corals and contacting organisms directly influenced the abundance of interactions between benthic organisms, regardless of the physical or biological characteristics of the habitat and of the interacting organisms. In addition, coral species interacted more with the most abundant benthic group, the epilithic algal matrix, in all areas. Nevertheless, some evidence was found about biological mechanisms helping to explain the structure of the studied interactions, although to a lesser extent. The obtained networks presented high nestedness and connectance, but low modularity. These patterns indicate the low specificity of the studied interactions and reinforce the role of abundance as an important driver of contacts between sessile organisms in shallow hard bottom ecosystems.     

Bridging a seasonal torrent: The Melfa river,southern Lazio,Italy

The Melfa River is a torrent of the intramontane Lower Liri Valley, which has been a difficult barrier to cross since ancient times. It is dry and can be forded during the summer, but it experiences high floods during rainy reasons, with recurrent disruption of bridges. In Iron Age and early Roman times, fords and bridges were located near the confluence of the river with the valley plain, servicing the ancient Via Pedemontana. Later, faster routes with bridges were moved toward the flatter central area of the valley. There, Romans selected a crossing through wide braided reaches, taking advantage of fording, but consistently losing low lying, long bridges. Traces of one and possibly two such bridges remain along what was the Via Latina, from Fregellae to Aquino. For such bridges, the Romans used relatively strong piers, probably linked with readily detachable (by floods) and replaceable, wooden, flat roadways. The strategy of Medieval and Modern civilizations was instead to bridge the river in a more permanent way, with arches across the nearby deep gorges whose banks are composed of stable calcareous conglomerates and sandstones.     

Sub-basalt seismic imaging using optical-to-acoustic model building and wave equation datuming processing

The presence of highly heterogeneous basalt layers has a detrimental effect on seismic imaging of underlying structures. Due to the prevalence of basalt, the challenge of imaging below basalts impinges on a broad spectrum of geological problems, from hydrocarbon exploration to volcano seismology. Both internal basalt characteristics and rough interfaces can degrade the sub-basalt image quality. In this paper we investigate the effects of both internal and surface heterogeneity on the wavefield. Using highly heterogeneous models of basalts derived from optical imagery and borehole sonic logs, combined with wave simulations to generate synthetic data, we explore the causes of poor sub-basalt imagery. We establish the significant role that surface roughness plays in the imagery problem and demonstrate, through a novel application of wave equation datuming, how to suppress its effect. The methodology demonstrated herein may be applicable in any environment where heterogeneous surface structures/interfaces severely degrade seismic image quality.     

Cement stratigraphy: image probes of cathodoluminescent facies

Cement stratigraphy of carbonates aims to establish the chronology of processes involved in the rock diagenesis. Regional cement stratigraphy allows correlations and understanding of the petrological heterogeneities in reservoirs and aquifers, but is a long and rigorous approach. This article exposes a methodology of image analysis that facilitates the spatial correlation of diagenetic events in carbonate rocks. Based on the statistical comparison of signals extracted from the red spectrum emission of cathodoluminescence digital images, it gives via crosscorrelation a measure of similarity (values scaled from minimum −1 to maximum 1) between two cathodoluminescence facies. Cementation events and diagenetic chronologies can thus be quickly correlated without the support of a full chronology, the model normally established on cement morphologies, petrological analyses and cathodoluminescence zonation sequences. A case study from two Upper Kimmeridgian Mount Salève outcrops (France) illustrates this methodology. Their diagenetic sequences recorded in cathodoluminescent cements are presented and being compared. The final statistical similarity between the two outcrops reaches an index of R = 0.78. This result is sustained by petrological and geochemical analyses such as alizarine–ferricyanure stained thin sections, X microfluorescence mapping of elements, and microthermometry of fluid inclusions.     

The latest Ursus spelaeus in Italy,a new contribution to the extinction chronology of the cave bear

The skeleton of a young prime adult cave bear, Ursus spelaeus, was found in Chiostraccio Cave (Siena, Tuscany, central Italy), only slightly buried under rock falls. The specimen was dated yielding a conventional age of 24,030 ± 100 ¹⁴C yr BP (29,200–28,550 cal yr BP), which makes it the latest known representative of the species in Italy. The skeleton was accompanied by the remains of wolf (Canis lupus), wild boar (Sus scrofa), aurochs (Bos primigenius), red deer (Cervus elaphus), roe deer (Capreolus capreolus), bat (Vespertinus murinus), and crow (Corvus monedula). The site seems confirming that the latest Italian U. spelaeus populations shared the risk of intrusion. The association of the cave bear with other animals suggests that the assemblage is an attritional palimpsest of remains of different species not originally associated in life. Cave bears were probably more vegetarian than brown bears and possibly became extinct when plant productivity dropped at the onset of MIS 2. Central and southern Italy may have offered isolated and sheltered refugia for cave bears.     

Evolution and architecture of a West Mediterranean Upper Pleistocene to Holocene coastal apron‐fan system

The Quaternary deposits of tectonically stable areas are a powerful tool to investigate high‐frequency climate variations (<10 ka) and to distinguish allogenic and autogenic factors controlling deposition. Therefore, an Upper Pleistocene–Holocene coastal apron‐fan system in north–western Sardinia (Porto Palmas, Italy) was studied to investigate the relations between climate changes, sea‐level fluctuations and sediment source‐supply that controlled its development. The sedimentary sequence records the strong influence of local (wet/dry) and worldwide (sea‐level) environmental variations in the sedimentation and preservation of the deposits. A multi‐disciplinary approach allowed subdivision of the succession into four major, unconformity‐bounded stratigraphic units: U1 U2, U3 and U4. Unit U1, tentatively dated to the warm and humid Marine Isotopic Stage (MIS) 5, consists of sandy, gravelly coastal/beach deposits developed during high sea‐level in low‐lying areas. Unit U2 consists of debris‐flow dominated fan‐deposits (ca 74 ka; MIS 4), preserved as partial fills of small valleys and coves. Unit U2 is mainly composed of reddish silty conglomerate to pebbly siltstones sourced from the Palaeozoic metamorphic inland hills (bedrock), superficially disintegrated during the preceding warm, vegetation‐rich MIS 5. The cold and semi‐arid climate strongly reduced vegetation cover along the valley flanks. Therefore, sediment gravity‐flow processes, possibly activated by rainstorms, led to deposition of debris‐flow dominated fans. Unit U3 consists of water‐flow dominated alluvial‐fan deposits (ca 47 to 23 ka; MIS 3), developed on a slightly inclined coastal plain. Unit U3 is composed of sandstone and sandy conglomerate fed from two main sediment sources: metamorphic inland bedrock and Quaternary bioclastic‐rich shelf‐derived sands. During this cold phase, sea‐level dropped sufficiently to expose bioclastic sands accumulated on the shelf. Frequent climate fluctuations favoured inland aeolian transport of sand during dry phases, followed by reworking of the aeolian bodies by flash floods during wet phases. Bedrock‐derived fragments mixed with water‐reworked, wind‐blown sands led to the development of water‐flow dominated fans. The Dansgaard–Oeschger events possibly associated with sand landward deflation and main fan formations are Dansgaard–Oeschger 13 (ca 47 ka), Dansgaard–Oeschger 8 (ca 39 ka) and Dansgaard–Oeschger 2 (ca 23 ka). No record of sedimentation during MIS 2 was observed. Finally, bioclastic‐rich aeolianites (Unit U4, ca 10 to 5 ka; MIS 1), preserved on a coastal slope, were developed during the Holocene transgression (ca 10 to 5 ka; MIS 1). The studied sequence shows strong similarities with those of other Mediterranean sites; it is, however, one of the few where the main MIS 4 and MIS 3 climatic fluctuations are registered in the sedimentary record.     

Shoal‐water deltas in high‐accommodation settings: Insights from the lacustrine Valimi Formation (Gulf of Corinth,Greece)

The stratigraphic architecture of shoal‐water deltaic systems developed in low‐accommodation settings is relatively well‐known. In contrast, the features of shoal‐water deltas developed in high‐accommodation settings remain relatively poorly documented, especially when compared with the available data sets for Gilbert‐type deltaic systems developed in the same settings. The lacustrine Valimi Formation (Gulf of Corinth, Greece) provides an opportunity to investigate the facies assemblage and architectural style of shoal‐water deltaic systems developed in high‐accommodation settings. The studied interval accumulated during the Pliocene and Pleistocene and represents part of the early syn‐rift Gulf of Corinth succession. Six facies associations, each described in terms of depositional processes and geometries, have been identified and interpreted to represent a range of proximal to distal deltaic sub‐environments: delta plain, distributary channel, mouth‐bar, delta front, prodelta and open lake. The facies associations and their architectural elements reveal characteristics which are not common in traditionally described shoal‐water deltas. Of note, different facies arrangements are observed in the distributary channels in different sectors of the delta, passing from thick single‐storey channel fills embedded within delta‐plain fines in landward positions, to thin, amalgamated and multi‐storey channels closer to the river mouth. This study proposes a new depositional model for shoal‐water deltas in high‐accommodation settings documenting, for the first time, that shoal‐water delta deposits can form a substantial part of stratigraphic successions that accumulate in these settings. The proposed depositional model provides new criteria for the recognition and interpretation of these deposits; the results of this study have applied significance for reservoir characterization.     

Sensitivity of goodness-of-fit statistics to rainfall data rounding off

An analysis based on the L-moments theory suggests of adopting the generalized Pareto distribution to interpret daily rainfall depths recorded by the rain-gauge network of the Hydrological Survey of the Sardinia Region. Nevertheless, a big problem, not yet completely resolved, arises in the estimation of a left-censoring threshold able to assure a good fitting of rainfall data with the generalized Pareto distribution. In order to detect an optimal threshold, keeping the largest possible number of data, we chose to apply a “failure-to-reject” method based on goodness-of-fit tests, as it was proposed by Choulakian and Stephens [Choulakian, V., Stephens, M.A., 2001. Goodness-of-fit tests for the generalized Pareto distribution. Technometrics 43, 478-484]. Unfortunately, the application of the test, using percentage points provided by Choulakian and Stephens (2001), did not succeed in detecting a useful threshold value in most analyzed time series. A deeper analysis revealed that these failures are mainly due to the presence of large quantities of rounding off values among sample data, affecting the distribution of goodness-of-fit statistics and leading to significant departures from percentage points expected for continuous random variables. A procedure based on Monte Carlo simulations is thus proposed to overcome these problems.