Lethal Thermal Impact at Periphery of Pyroclastic Surges: Evidences at Pompeii

Background: The evaluation of mortality of pyroclastic surges and flows (PDCs) produced by explosive eruptions is a major goal in risk assessment and mitigation, particularly in distal reaches of flows that are often heavily urbanized. Pompeii and the nearby archaeological sites preserve the most complete set of evidence of the 79 AD catastrophic eruption recording its effects on structures and people. Methodology/Principal Findings: Here we investigate the causes of mortality in PDCs at Pompeii and surroundings on the bases of a multidisciplinary volcanological and bio-anthropological study. Field and laboratory study of the eruption products and victims merged with numerical simulations and experiments indicate that heat was the main cause of death of people, heretofore supposed to have died by ash suffocation. Our results show that exposure to at least 250uC hot surges at a distance of 10 kilometres from the vent was sufficient to cause instant death, even if people were sheltered within buildings. Despite the fact that impact force and exposure time to dusty gas declined toward PDCs periphery up to the survival conditions, lethal temperatures were maintained up to the PDCs extreme depositional limits. Conclusions/Significance: This evidence indicates that the risk in flow marginal zones could be underestimated by simply assuming that very thin distal deposits, resulting from PDCs with poor total particle load, correspond to negligible effects. Therefore our findings are essential for hazard plans development and for actions aimed to risk mitigation at Vesuvius an

Benthic fluxes and nitrate reduction activity in a marine park (Northern San Jorge Gulf) from Patagonia Argentina

The Northern San Jorge Gulf (NSJG) was declared Coastal Marine Park in 2008 with the goal of preserving its biodiversity. In situ benthic fluxes experiments were performed using an opaque chamber in Sara Creek (SC) and Malaspina Creek (MC). Moreover, ex situ nitrate reduction activity was assessed using a continuous flow-through system. Benthic fluxes in MC, showed a consumption of oxygen (794 ± 196 mg m−2 h−1) and nitrate (103 ± 68 µmol m−2 h−1) by sediment and release of ammonium (175 ± 60 µmol m−2 h−1), phosphate (66 ± 10 µmol m−2 h−1) and silicate (116 ± 66 µmol m−2 h−1) towards the water column. In SC, the same pattern was observed and the fluxes values were 375 ± 132, 128 ± 1, 76 ± 12, 39 ± 24 and 133 ± 81, respectively. Only, ammonium and oxygen fluxes showed significant differences between sites, due to the highest organic matter content and the particular hydrodynamic conditions in MC. These are the first benthic flux measurements made within the protected area. Nitrate uptake rate, based on Michaelis–Menten kinetic, was Km: 155.3 µM and Vmax: 0.053 µM g−1 h−1 in SC and Km: 131.2 µM and Vmax: 0.039 µM g−1 h−1 in MC. Considering the nitrate dynamic we concluded that the sediments both SC and MC act as a sink of nitrate. This ion could be principally used as a terminal electron acceptor during the oxidation process of organic compounds in sediments of NSJG.Fil: Torres, Américo Iadran. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Faleschini, Mauricio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Esteves, Jose Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentin

Perspective: Continental Inputs of Matter into Planktonic Ecosystems of the Argentinean Continental Shelf- the Case of Atmospheric Dust

Land-derived dissolved and particulate matter (allochthonous matter) affect pelagic ecosystems by changing factors which include light penetration, nutrient availability, substrate concentration, and in general, biogeochemical cycles in the ocean. In a context of growing anthropogenic impact, this material may not only increase its load but also carry toxic substances. Riverine runoff is the most studied mechanism of particulate matter input from the continent to the sea in the southern region of South America where the continental shelf is widest (e.g., Atlantic Patagonia). However, there are other sources of particulate matter which are not affected by rivers in this semiarid region: aeolian material. Winds in this region (notably the Southern Hemisphere westerlies) are the only way continental aeolian material (atmospheric aerosols or “dust”) can reach not only the shelf but even further onto oceanic HNLC (high nutrient–low chlorophyll) regions of the Atlantic Southern Ocean. This potential impact of Patagonian dust beyond the continental shelf attracts the attention of the global climate community, and at the same time, it opens questions about the potential effects of dust in coastal waters. According to previous work and ongoing studies, deposited particles can have significant impacts in the chemical and biological components in the euphotic zone. However the effects of this airborne material in plankton communities of South America are largely unknown, mostly due to the lack of in situ studies and observations. Since the events of dust mobilization, transport, and deposition are expected to increase (due to climate change) and interact with other global change factors such as warming and more intensive land use, the influence of dust input may become more prominent for coastal and oceanic regions of southern South America in the next decades.Fil: Crespi Abril, Augusto Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Barbieri, Elena Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Gracia Villalobos, Leilen Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Soria, Rodrigo Gaspar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Paparazzo, Flavio Emiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Paczkowska, Joanna Marianna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Gonçalves, Rodrigo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentin