We investigated helium isotopes on gas extracted by crushing from melt and fluid inclusions in minerals from Plinian and inter-Plinian tephra and lavas of Vesuvius, Italy. Erupted products of ...different ages were considered, from Avellino eruption (1995 BCE) to the last eruption of 1944, with special focus on the
79 AD
Plinian eruption.
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ratios between 1.5 and 2.7
R
A
were measured, with the highest values associated with rocks representative of the roof and the walls of the magma chambers (cumulates). Lowest values occurred in sanidines representative of magma-skarn interfaces. Noteworthy, the highest measured values of the
79 AD
pumices were comparable with both lavas and tephra emitted from flank vents and under open-conduit conditions during the
Medieval Period
and
Present Period
of Vesuvius activity, and present-day fumarolic discharges.
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values are buffered within an extended, deep-seated reservoir at about 10
km
filled with magma rising from the mantle. A fact that might potentially limit the accuracy of future eruption forecasting through monitoring of
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3
changes in Vesuvius fumaroles. Ageing and interaction with crustal rocks emerged as possible mechanisms that lowered the
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ratio of the melt during its intra-crustal magma chambers stay, with highest values associated with more dynamic conditions.
In continental margins, canyons appear to act as natural conduits of sediments and organic matter from the shelf to deep basins, providing an efficient physical pathway for transport and accumulation ...of particles with their associated land-produced contaminants. However, these mechanisms have not been yet sufficiently explored by geochemical markers. The continental slope of the south Sardinia has been used as a natural laboratory for investigating mechanisms and times of transfer dynamics of contaminants from land to sea and from shelf to deep sea through an articulated system of submarine canyons. Here, dynamics of contaminants have been investigated in a pilot area of the central Mediterranean basin (Gulf of Cagliari, S Sardinia) where important industrial plants are sited since beginning of the last century. Five sediment cores dated by 210Pb and 137Cs reveal: i) a complex dynamics of organic and inorganic contaminants from point source areas on land to the deep sea and ii) a crucial role played by canyons and bottom morphology as primary pathway conveying sediments and associated contaminants from sources to very far deep sea environments. In particular, this study provides new integrated tools to properly understand mechanisms of connection between coastal sectors and deep sea. This is challenging mostly in regions where coastal pollution could represent critical threats for larger areas of the Mediterranean Sea.
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•Bottom morphology reveals a complex and articulated system of submarine canyons.•High-resolution stratigraphic markers for sedimentary marine records•Canyons as primary pathway conveying sediments and associated contaminants.
The loss of coral habitats and associated biodiversity have direct effects both on the physical dynamics of the coast and on natural resources, threatening the survival of local populations. ...Conservative actions, such as the creation of new Marine Protected Areas, are urgent measures needed to face climate change. Managers need fast and simple methods to evaluate marine habitats for planning conservation areas. Here, we present the application of an Ecological Quality Index (EQI), developed for regional-scale habitat maps of the Atlas of the Marine Coastal Habitats of the Kingdom of Tonga, by processing Copernicus Sentinel-2 imagery. Both the habitat mapping classification and the EQI application were focused on the importance of coral reef, seagrass and mangrove habitats, both as natural defense and sustenance for the local populations. Twelve main Pacific reef habitats were evaluated through a three-level EQI score assigned to six parameters: nursery ground, connectivity, species reservoir, fish attraction, biodiversity and primary production. The EQI was integrated into a developed georeferenced database associated to the QGIS software providing the ability to identify on the maps the area of interest and the associated habitats, and to quantify their ecological relevance. The EQI is proposed as a tool that can offer to stakeholders and environmental managers a simple and direct indicator of the value of the marine coastal environment. The index may be handled for management purposes of vast areas with remote and uninhabited islands.
Sustainable and ecosystem-based marine spatial planning is a priority of Pacific Island countries basing their economy on marine resources. The urgency of management coral reef systems and associated ...coastal environments, threatened by the effects of climate change, require a detailed habitat mapping of the present status and a future monitoring of changes over time. Here, we present a remote sensing study using free available Sentinel-2 imagery for mapping at large scale the most sensible and high value habitats (corals, seagrasses, mangroves) of Palau Republic (Micronesia, Pacific Ocean), carried out without any sea truth validation. Remote sensing ‘supervised’ and ‘unsupervised’ classification methods applied to 2017 Sentinel-2 imagery with 10 m resolution together with comparisons with free ancillary data on web platform and available scientific literature were used to map mangrove, coral, and seagrass communities in the Palau Archipelago. This paper addresses the challenge of multispectral benthic mapping estimation using commercial software for preprocessing steps (ERDAS ATCOR) and for benthic classification (ENVI) on the base of satellite image analysis. The accuracy of the methods was tested comparing results with reference NOAA (National Oceanic and Atmospheric Administration, Silver Spring, MD, USA) habitat maps achieved through Ikonos and Quickbird imagery interpretation and sea-truth validations. Results showed how the proposed approach allowed an overall good classification of marine habitats, namely a good concordance of mangroves cover around Palau Archipelago with previous literature and a good identification of coastal habitats in two sites (barrier reef and coastal reef) with an accuracy of 39.8–56.8%, suitable for survey and monitoring of most sensible habitats in tropical remote islands.
Isotopic composition of mercury (Hg) in marine organisms and sediment cores was used to identify sources and reconstruct historical trends of contamination in the coastal-marine area of Rosignano ...Solvay (Italy), affected by Hg pollution from a chlor-alkali plant on the near land. Sediments show a wide range of Hg concentration and Hg isotope signatures. Particularly, coupled Hg concentration and δ202Hg values trace inputs from different sources. The two depth-profiles clearly indicate three distinct periods: “pre-industrial” (before 1941), “industrial” (between 1941 and 2007) and “post-industrial” (after 2007) ages. This is also corroborated by sediment chronology, using 210Pb dating method, validated through 137Cs. Marine organisms are characterized by Hg isotope signatures comparable to “post-industrial” surface sediments. Notably, specimens of Mullus spp. evidence isotope composition comparable to the “industrial” sediments, thus suggesting a still active role of those sediments as source of Hg for the benthic fish compartment. The small amount of MIF and the Δ199Hg/Δ201Hg ratio recorded in organisms are reasonably consistent with limited processes of MMHg demethylation in the water column.
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•The Hg isotope composition in marine organisms and core sediments was explored.•Sediments chronology was determined by 210Pb dating method.•Historical trend in Hg contaminated sediments was reconstructed.•Benthic organisms and surface sediments have similar isotopic composition.
In this study, site-specific natural background levels (NBLs) were determined for 18 elements (Al, As, Be, Cd, Co, Cu, Cr, Fe, Hg, K, Mn, Mo, Ni, Pb, Tl, U, V, and Zn) in two sediment cores collected ...offshore the Bagnoli-Coroglio brownfield site (Gulf of Pozzuoli, southern Italy) to accurately assess the degree of contamination and the historical trends in Heavy Metals (HMs) enrichment. This objective was pursued taking in account the high temporal and spatial variability of the geochemical properties of the area due to the local geothermal activity. Moreover, the temporal variation of Polycyclic Aromatic Hydrocarbons (PAHs) was investigated.
226
Ra was used as an extraordinary marker to confirm
210
Pb dating. It especially allowed defining the geochronological framework of the sediment core closer the brownfield up to around 1500, providing compelling support to correlate the investigated elements’ occurrences with natural geogenic dynamic. Sediment samples were accurately dated and analyzed for chemical and particle size composition. The contamination factor (Cf) and the pollution load index (PLI) showed very high enrichment of Cd, Cu, Hg, Pb, and Zn. The contamination profiles of HMs and PAHs follow the same pattern in both sediment cores, increasing from deep to upper layers. The highest contamination levels for HMs and PAHs were observed between 10 and 30 cm, corresponding to the periods of most intense industrial activity. Decreasing trends of pollutants were observed in the surface layers (0–10 cm), probably affected by a natural attenuation process due to the cessation of industrial activities.
Settling fluxes and sediment accumulation rates in coastal Tema Harbour (Ghana) were investigated by the combined analyses of results in sediment traps and sediment cores. Sediment traps were ...deployed at 5 stations within the Tema Harbour at two sampling depths and were retrieved every two weeks till the end of 12weeks to estimate the Settling Fluxes (SFs). Four sediment cores from the harbour were analysed for their radioactivity (7Be, 234Th, 210Pb, 212Pb, 226Ra, 40K and 137Cs) profiles to quantify Sediment Accumulation Rates (SARs). The sediment cores exhibited variable bulk density profiles, indicating highly dynamic and non-steady sedimentation conditions. 7Be-derived gross-estimates of very recent SARs using the constant flux-constant sedimentation (CF-CS) model were in the range of 2.5–9.0g·cm−2·y−1. These values were much lower than the estimated average SFs (15.2–53.8g·cm−2·y−1), indicating sediment resuspension plays an important role. On a decadal time scale, conventional 210Pb sediment dating models did not allow any estimation of SARs in the Tema Harbour. Thus, the 210Pb-based TERESA model was applied to depict a reliable scenario for sedimentation with time-averaged SARs in the range of 1.4–3.0g·cm−2·y−1 and fluxes of matter contributed by the marine inflow and local sources. Sediment accretion rates of 1.7–3cm·y−1 were also inferred, which may pose a moderate problem of sustainability for the Tema Harbour. This study reveals how the geochemical behaviour of different radionuclides with Gamma spectrometry in the marine environment can be used to obtain reliable information on the complex dynamics of Suspended Particulate Matter (SPM), even in a very disturbed and anthropic environment as a coastal harbour area where (1) conventional 210Pb-based dating methods fail and (2) the use of sediment traps and 234Th and 7Be profiles in sediment cores show serious constraints.
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•Sediment traps deployed and sediment cores collected in Tema Harbour for the first time.•A multi-tracer approach with Gamma spectrometry is applied in a disturbed harbour area.•TERESA model is a good tool in disturbed sites where common 210Pb dating models fail.•TERESA model sediment accumulation rates in Tema Harbour are 1.4–3.0g·cm−2·y−1.
This paper is focused on the field-evidence of environmental hazard associated with flood events in highly contaminated marine coastal areas. The Crotone site (Ionian Sea), in the 1900s hosted a ...large industrial settlement (with the largest plant in Europe of zinc production, phosphorus manufacture, etc.) which left a severe legacy of environmental pollution. Here, we report the results of an investigation related to the distribution of heavy metals (Zn, Pb, Cd, Cu) in 230 sediment cores that allowed a detailed reconstruction of the contamination due to the discharge at sea of industrial wastes deriving from the Zn-sulphides leaching processes. High concentrations of heavy metals (e.g., Zn > 5000 mg kg−1) accumulated in sediments of the seabed along coastline, exposed to the fluvial and coastal dynamics, act as a potential long-term source of pollution for the marine ecosystem. Fingerprints of historically flash flood events evidenced in two 210Pb dated sediment cores suggest that these catastrophic events played a crucial role in the land-to-sea transferring (and sequent dispersing effects) of highly polluted sediments. Anomalous depositions of heavy metals-rich sediments in the offshore system (4–6 km from the coastline) testify secondary contamination due to mobilization and redistribution of old contaminated sediment due to flood events. These interactions between natural and anthropic hazards trigger cumulative mechanisms of multiple-pollution and transfer of contamination from polluted nearshore to offshore nearly pristine areas trough main canyon axes.
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•Historically polluted sediments affect the status of the Crotone marine coastal area.•Flood events remobilize and redistribute polluted sediments in the offshore.•210Pb dated sedimentary records document multiple episodes of flooding on-land.•Extreme events amplify effects of pollution in the coastal system.
Gorgonian corals are long-lived, slow-growing species exhibiting slow population dynamics. Demographic data collected over a period of 11 yr on a small population of temperate, canopy-forming ...gorgonians dwelling near the edge of the summer thermocline in the northwestern Mediterranean Sea enabled us to assess its responses to the large mortality events that occurred in 1999 and 2003. Changes in population density, size structure and recruitment were examined. Overall, 2101 adult colonies and recruits were observedin situand 240 photographic plots analyzed. During the first 3 years (2004 to 2006) after the mass mortalities, our measurements revealed a dramatic reduction in the density of healthy colonies (90% suffered total or partial mortality), a shift in the dominant size class towards smaller size and a significant reduction in recruitment. In the following years (2007 to 2008) a significant recovery of injured colonies was found, with almost complete detachment of the dead colonies, a reduction in mortality and a 4-fold increase in recruitment. These findings indicate clear-cut restoration trends of the population, suggesting that recovery after extensive mortality could be faster than predicted by our current knowledge of gorgonian population dynamics.
BARSANTI, M., CALDA, N and VALLONI, R., 2011. The Italian Coasts: a Natural Laboratory for the Quality Evaluation of Beach Replenishments. In: Micallef, A. (ed.), MCRR3-2010 Conference Proceedings, ...Journal of Coastal Research, Special Issue, No. 61, pp. 1–07. Grosseto, Tuscany, Italy, ISSN 0749-0208. The present paper describes the joint research recently carried out by the University of Parma and the ENEA Marine Research Centre of La Spezia for the characterization of grain-size and petrography of the Native sediments of the Italian marine coastal territory. The work aims to establish a protocol for the evaluation of the “quality’ of artificial beach replenishment fills. GIS technologies have been used to create a national database on coastal cells. The Italian territory is composed of 188 Littoral Cells if coastal stretches less than 5 km long are ignored. On these Cells over two hundred sample couples of dune and beach sediment were collected and analysed for grain-size and thin-section petrography. The original petrographic classification adopted here is also suitable to the collection of literature data and is based on four fundamental sediment sources named Terrigenous silicate, Terrigenous carbonate, Indigenous and Pyroclastic, that may expand into eight petrographic compositions depending on the prevailing grain type: Quartzitic, Feldspathic, Metamorphilithic, Volcanilithic, Dololithic, Calcilithic, Bioclastic and Tuffitic. The foreshore sands reach their maximum diameters in Sardinia and Sicily where the Median (D50) ranges 0.801.50 phi (medium and coarse sands, with D50 averaging 0.50 mm). The foreshore sands show their minimum diameters in the Adriatic coast where the Median ranges 2.0–3.0 phi. These grain-size trends are also reflected in the dune sands that reach their maximum values in Sardinia where D50 ranges 1.00–2.50 phi. Beach-dune sample couplets indicate that the sediment textural maturation is poorly effective in the Adriatic coasts and highly effective in the Tyrrhenian coasts.
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Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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