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Gerard Blanc - One of the best experts on this subject based on the ideXlab platform.

  • Geochemical Survey and metal bioaccumulation of three bivalve species crassostrea gigas cerastoderma edule and ruditapes philippinarum in the nord medoc salt marshes gironde estuary france
    Science of The Total Environment, 2005
    Co-Authors: Magalie Baudrimont, Jorg Schafer, Veronique Marie, Regine Maurybrachet, Cecile Bossy, A Boudou, Gerard Blanc
    Abstract:

    A 15-month experiment combining a Geochemical Survey of Cd, Cu, Zn and Hg with a bioaccumulation study for three filter-feeding bivalve species (oysters, Crassostrea gigas; cockles, Cerastoderma edule; and clams, Ruditapes philippinarum) was conducted in a breeding basin of the Nord Medoc salt marshes connected to the Gironde estuary, which is affected by historic polymetallic pollution. Regular manual surface measurements of temperature, salinity, pH and dissolved O(2) concentration and hourly multiprobe in situ measurements throughout several periods for 6-8 weeks were performed. The Geochemical behavior of metals in water, suspended particulate matter and sediment and their ecotoxicological impact on the three bivalve species were evaluated by in situ exposure of juvenile oysters (water column) and adult cockles and clams (sediment surface). The physico-chemical parameters reflected seasonal variations and basin management. A distinct daily periodicity (except salinity) indicated intense photosynthesis and respiration. In summer, low dissolved O(2) saturations ( approximately 40-50%) occurred in the early morning at 30 cm above the sediment, whereas in depressions, the water column near the sediment surface was suboxic. Cadmium, Zn and Cu concentrations in suspended particulate matter exceeded typical estuarine values and were much higher than the homogeneously distributed concentrations in different depth ranges of the basin sediment. Particles collected in sediment traps showed intermediate metal concentrations close to sediment values. These results suggest trace metal recycling due to reductive dissolution under suboxic conditions at the sediment surface resulting in trace metal release to the water column and adsorption onto suspended particles. Dissolved Cd, Zn and Hg concentrations (e.g. 13-136 ng l(-1); 0.3-25.1 microg l(-1) and 0.5-2.0 ng l(-1), respectively) in the basin corresponded to the concentration range typically observed in the Gironde estuary, except for some maximum values attributed to metal recycling. In contrast, dissolved Cu concentrations (1.08-6.08 microg l(-1)) were mostly higher than typical estuarine values, probably due to recycled Cu complexation by dissolved organic matter. Growth, bioaccumulation rates and kinetics in the whole soft body of the bivalves were analyzed every 40 days. Although Cd bioaccumulation of oysters was lower in the basin than in the estuary during the same period (27,000 ng g(-1), dry weight and 40,000 ng g(-1), respectively) these values are largely above the new human consumption safety level (5000 ng g(-1), dw; European Community, 2002). For cockles and clams, Cd bioaccumulation was lower, reaching 1400 ng g(-1) and 950 ng g(-1), respectively. Similar results were obtained for Zn and Cu suggesting physiological differences between the species and/or differences in the exposure of the organisms due to physico-chemical conditions and metal distribution between dissolved and particulate phases. In contrast, Hg bioaccumulation was highest for cockles reaching bioconcentration factors of approximately 200,000, which even exceeded that of Cd in oysters (50,000) for the same exposition period. Nevertheless, Hg concentrations remained relatively low in the three bivalve species.

  • cadmium contamination of three bivalve species oysters cockles and clams in nord medoc salt marshes gironde estuary france Geochemical Survey and metal bioaccumulation kinetics
    Journal De Physique Iv, 2003
    Co-Authors: Magalie Baudrimont, Jorg Schafer, Veronique Marie, Regine Maurybrachet, Cecile Bossy, Gilles Durrieu, A Palvadeau, E Maneux, A Boudou, Gerard Blanc
    Abstract:

    A historical Cd pollution of the Lot-Garonne River system (France) has led to the contamination of sediment and water of the Gironde Estuary. In spite of the decrease of fluvial Cd inputs since the early 90ies, Cd concentrations in the Gironde oysters remain higher than European norms (5 μg.g -1 dry mass) and the zone D classification of the estuary prohibits bivalve production and harvesting for human consumption. A Geochemical Survey in salt marshes used for aquaculture (crustaceans) has been conducted in order to assess the heavy metal contamination level in these systems periodically alimented by the Gironde water, accompanied by caging experiments on three bivalve species of economical interest: oysters (Crassostrea gigas), cockles (Cerastoderma edule) and clams (Ruditapes philippinarum) to study heavy metal accumulation in these organisms. Distribution of heavy metals in this system is controlled by bioGeochemical processes and is independent of routine water management. Contamination levels in the studied species indicate the high accumulation of Cd by oysters. On the other hand, Cd concentrations in benthic species, such as cockles and clams, are clearly lower than European safety limits for human consumption.

Orlando Vaselli - One of the best experts on this subject based on the ideXlab platform.

  • boron pollution in the shallow groundwater system from isola di castelluccio central eastern tuscany evidences from a Geochemical Survey and new remediation perspectives from a recently installed hydraulic barrier and hydrogeological modelling
    Bollettino Della Societa Geologica Italiana, 2021
    Co-Authors: Marta Lazzaroni, Barbara Nisi, Franco Tassi, Mattia Ceccatelli, Luca Rossato, Stefania Venturi, Riccardo Fanti, Orlando Vaselli
    Abstract:

    A severe boron pollution has been recognized in the shallow aquifer of Isola di Castelluccio (central-eastern Tuscany, Italy) since 2009. Previous investigations showed that the high boron concentrations (up to 57 mg L-1) were related to an anthropogenic source. It was likely due to current and/or past industrial and artisanal activities, which were using B-compounds during their productive cycles. However, a univocal source of boron has so far not been recognized. In this work, we present and discuss new Geochemical and isotopic data related to an extensive campaign (June 2016) carried out in 33 domestic well and piezometer waters. In addition, the results from a three-weekly to monthly monitoring Survey (from August 2014 to December 2019) on selected waters were used to recognize signals in response to dry and wet periods or related to the presence of the recently installed hydraulic barrier. To verify the efficiency of the hydraulic barrier a numerical model of the shallow aquifer was performed by using the MODFLOW computer program. This study has allowed to identify where the source of contamination is likely located. This implies that specific investigations can now be carried out to definitively remove the anthropogenic source of boron.

  • the domuyo volcanic system an enormous geothermal resource in argentine patagonia
    Journal of Volcanology and Geothermal Research, 2014
    Co-Authors: G Chiodini, Orlando Vaselli, Franco Tassi, Caterina Liccioli, Sergio Calabrese, S Caliro, Alberto T Caselli, Mariano Agusto, W Dalessandro
    Abstract:

    Abstract A Geochemical Survey of the main thermal waters discharging in the southwestern part of the Domuyo volcanic complex (Argentina), where the latest volcanic activity dates to 0.11 Ma, has highlighted the extraordinarily high heat loss from this remote site in Patagonia. The thermal water discharges are mostly Na-Cl in composition and have TDS values up to 3.78 g L− 1 (El Humazo). A simple hydroGeochemical approach shows that 1,100 to 1,300 kg s− 1 of boiling waters, which have been affected by shallow steam separation, flow into the main drainage of the area (Rio Varvarco). A dramatic increase of the most conservative species such as Na, Cl and Li from the Rio Varvarco from upstream to downstream was observed and related solely to the contribution of hydrothermal fluids. The equilibrium temperatures of the discharging thermal fluids, calculated on the basis of the Na-K-Mg geothermometer, are between 190 °C and 230 °C. If we refer to a liquid originally at 220 °C (enthalpy = 944 J g− 1), the thermal energy release can be estimated as high as 1.1 ± 0.2 GW, a value that is much higher than the natural release of heat in other important geothermal fields worldwide, e.g., Mutnovsky (Russia), Wairakei (New Zealand) and Lassen Peak (USA). This value is the second highest measured advective heat flux from any hydrothermal system on Earth after Yellowstone.

  • distribution of gaseous hg in the mercury mining district of mt amiata central italy a Geochemical Survey prior the reclamation project
    Environmental Research, 2013
    Co-Authors: Orlando Vaselli, Pablo Higueras, Barbara Nisi, Jose Maria Esbri, Jacopo Cabassi, Alba Martinezcoronado, Franco Tassi, Daniele Rappuoli
    Abstract:

    Abstract The Mt. Amiata volcano is the youngest and largest volcanic edifice in Tuscany (central-northern Italy) and is characterized by a geothermal field, exploited for the production of electrical energy. In the past Mt. Amiata was also known as a world-class Hg district whose mining activity was mainly distributed in the central-eastern part of this silicic volcanic complex, and particularly in the municipality of Abbadia San Salvatore. In the present work we report a Geochemical Survey on Hg0 measurements related to the former mercury mine facilities prior the reclamation project. The Hg0 measurements were carried out by car for long distance regional Surveys, and on foot for local scale Surveys by using two LUMEX (915+ and M) devices. This study presents the very first Hg0 data obtained with this analytical technique in the Mt. Amiata area. The facilities related to the mining areas and structures where cinnabar was converted to metallic Hg are characterized by high Hg values (>50,000 ng m−3), although the urban center of Abbadia San Salvatore, few hundred meters away, does not appear to be receiving significant pollution from the calcine area and former industrial edifices, all the recorded values being below the values recommended by the issuing Tuscany Region authorities (300 ng m−3) and in some cases approaching the Hg background levels (3–5 ng m−3) for the Mt. Amiata area.

  • gas discharges from four remote volcanoes in northern chile putana olca irruputuncu and alitar a Geochemical Survey
    Annals of Geophysics, 2011
    Co-Authors: Franco Tassi, Orlando Vaselli, Felipe Aguilera, Thomas H Darrah, Eduardo Medina
    Abstract:

    We analyzed gas samples collected from fumaroles and bubbling pools at Irruputuncu, Putana, Olca and Alitar volcanoes located in the central Andes volcanic zone (northern Chile). The Irruputuncu and Putana fumarolic discharges showed outlet temperatures ranging from 83 ˚C to 240 ˚C and from 82 ˚C to 88 ˚C, respectively. The chemical and isotopic ( 3 He/ 4 He, d 13 C-CO 2 , d 18 O-H 2 O and dD-H 2 O) compositions of these discharges were similar to medium-to-high temperature volcanic gases from other active volcanoes in this sector of the Andean volcanic chain (e.g. Lascar volcano). Inorganic and organic gas geothermometers for the H 2 O-CO 2 -CO-H 2 , CO 2 -CH 4 and C 2 -C 3 alkenes-alkanes systems indicated equilibrium temperatures that exceed 500 ˚C at the gas sources. These relatively high temperatures are in agreement with the presence of relevantly high concentrations of magmatic gas emissions, including SO 2 . Olca and Alitar volcano fluid chemistries indicated lower amounts of magmatic-derived gas species, while both the helium and the water isotopic compositions suggested significant fractions of shallow, crustal/meteoric-originated fluids. These indicate contributions from a hydrothermal environment with temperatures <400 ˚C. The Geochemical and isotopic features derived from the present study show that the Irruputuncu, Putana, Olca and Alitar volcanoes should be considered as active and thus warrant periodic Geochemical monitoring to determine the evolution of these systems and their potential hazards.

  • low ph waters discharging from submarine vents at panarea island aeolian islands southern italy after the 2002 gas blast origin of hydrothermal fluids and implications for volcanic surveillance
    Applied Geochemistry, 2009
    Co-Authors: Franco Tassi, Bruno Capaccioni, Giorgio Caramanna, D Cinti, Giordano Montegrossi, L Pizzino, F Quattrocchi, Orlando Vaselli
    Abstract:

    Abstract A Geochemical Survey of thermal waters collected from submarine vents at Panarea Island (Aeolian Islands, southern Italy) was carried out from December 2002 to March 2007, in order to investigate (i) the Geochemical processes controlling the chemical composition of the hydrothermal fluids and (ii) the possible relations between the chemical features of the hydrothermal reservoir and the activity of the magmatic system. Compositional data of the thermal water samples were integrated in a hydrological conceptual model, which describes the formation of the vent fluid by mixing of seawater, seawater concentrated by boiling, and a deep, highly-saline end-member, whose composition is regulated by water-rock interactions at relatively high temperature and shows clear clues of magmatic-related inputs. The chemical composition of concentrated seawater was assumed to be represented by that of the water sample having the highest Mg content. The composition of the deep end-member was instead calculated by extrapolation assuming a zero-Mg end-member. The Na–K–Ca geothermometer, when applied to the thermal end-member composition, indicated an equilibrium temperature of approximately 300 °C, a temperature in agreement with the results obtained by gas-geothermometry.

Magalie Baudrimont - One of the best experts on this subject based on the ideXlab platform.

  • Geochemical Survey and metal bioaccumulation of three bivalve species crassostrea gigas cerastoderma edule and ruditapes philippinarum in the nord medoc salt marshes gironde estuary france
    Science of The Total Environment, 2005
    Co-Authors: Magalie Baudrimont, Jorg Schafer, Veronique Marie, Regine Maurybrachet, Cecile Bossy, A Boudou, Gerard Blanc
    Abstract:

    A 15-month experiment combining a Geochemical Survey of Cd, Cu, Zn and Hg with a bioaccumulation study for three filter-feeding bivalve species (oysters, Crassostrea gigas; cockles, Cerastoderma edule; and clams, Ruditapes philippinarum) was conducted in a breeding basin of the Nord Medoc salt marshes connected to the Gironde estuary, which is affected by historic polymetallic pollution. Regular manual surface measurements of temperature, salinity, pH and dissolved O(2) concentration and hourly multiprobe in situ measurements throughout several periods for 6-8 weeks were performed. The Geochemical behavior of metals in water, suspended particulate matter and sediment and their ecotoxicological impact on the three bivalve species were evaluated by in situ exposure of juvenile oysters (water column) and adult cockles and clams (sediment surface). The physico-chemical parameters reflected seasonal variations and basin management. A distinct daily periodicity (except salinity) indicated intense photosynthesis and respiration. In summer, low dissolved O(2) saturations ( approximately 40-50%) occurred in the early morning at 30 cm above the sediment, whereas in depressions, the water column near the sediment surface was suboxic. Cadmium, Zn and Cu concentrations in suspended particulate matter exceeded typical estuarine values and were much higher than the homogeneously distributed concentrations in different depth ranges of the basin sediment. Particles collected in sediment traps showed intermediate metal concentrations close to sediment values. These results suggest trace metal recycling due to reductive dissolution under suboxic conditions at the sediment surface resulting in trace metal release to the water column and adsorption onto suspended particles. Dissolved Cd, Zn and Hg concentrations (e.g. 13-136 ng l(-1); 0.3-25.1 microg l(-1) and 0.5-2.0 ng l(-1), respectively) in the basin corresponded to the concentration range typically observed in the Gironde estuary, except for some maximum values attributed to metal recycling. In contrast, dissolved Cu concentrations (1.08-6.08 microg l(-1)) were mostly higher than typical estuarine values, probably due to recycled Cu complexation by dissolved organic matter. Growth, bioaccumulation rates and kinetics in the whole soft body of the bivalves were analyzed every 40 days. Although Cd bioaccumulation of oysters was lower in the basin than in the estuary during the same period (27,000 ng g(-1), dry weight and 40,000 ng g(-1), respectively) these values are largely above the new human consumption safety level (5000 ng g(-1), dw; European Community, 2002). For cockles and clams, Cd bioaccumulation was lower, reaching 1400 ng g(-1) and 950 ng g(-1), respectively. Similar results were obtained for Zn and Cu suggesting physiological differences between the species and/or differences in the exposure of the organisms due to physico-chemical conditions and metal distribution between dissolved and particulate phases. In contrast, Hg bioaccumulation was highest for cockles reaching bioconcentration factors of approximately 200,000, which even exceeded that of Cd in oysters (50,000) for the same exposition period. Nevertheless, Hg concentrations remained relatively low in the three bivalve species.

  • cadmium contamination of three bivalve species oysters cockles and clams in nord medoc salt marshes gironde estuary france Geochemical Survey and metal bioaccumulation kinetics
    Journal De Physique Iv, 2003
    Co-Authors: Magalie Baudrimont, Jorg Schafer, Veronique Marie, Regine Maurybrachet, Cecile Bossy, Gilles Durrieu, A Palvadeau, E Maneux, A Boudou, Gerard Blanc
    Abstract:

    A historical Cd pollution of the Lot-Garonne River system (France) has led to the contamination of sediment and water of the Gironde Estuary. In spite of the decrease of fluvial Cd inputs since the early 90ies, Cd concentrations in the Gironde oysters remain higher than European norms (5 μg.g -1 dry mass) and the zone D classification of the estuary prohibits bivalve production and harvesting for human consumption. A Geochemical Survey in salt marshes used for aquaculture (crustaceans) has been conducted in order to assess the heavy metal contamination level in these systems periodically alimented by the Gironde water, accompanied by caging experiments on three bivalve species of economical interest: oysters (Crassostrea gigas), cockles (Cerastoderma edule) and clams (Ruditapes philippinarum) to study heavy metal accumulation in these organisms. Distribution of heavy metals in this system is controlled by bioGeochemical processes and is independent of routine water management. Contamination levels in the studied species indicate the high accumulation of Cd by oysters. On the other hand, Cd concentrations in benthic species, such as cockles and clams, are clearly lower than European safety limits for human consumption.

Franco Tassi - One of the best experts on this subject based on the ideXlab platform.

  • boron pollution in the shallow groundwater system from isola di castelluccio central eastern tuscany evidences from a Geochemical Survey and new remediation perspectives from a recently installed hydraulic barrier and hydrogeological modelling
    Bollettino Della Societa Geologica Italiana, 2021
    Co-Authors: Marta Lazzaroni, Barbara Nisi, Franco Tassi, Mattia Ceccatelli, Luca Rossato, Stefania Venturi, Riccardo Fanti, Orlando Vaselli
    Abstract:

    A severe boron pollution has been recognized in the shallow aquifer of Isola di Castelluccio (central-eastern Tuscany, Italy) since 2009. Previous investigations showed that the high boron concentrations (up to 57 mg L-1) were related to an anthropogenic source. It was likely due to current and/or past industrial and artisanal activities, which were using B-compounds during their productive cycles. However, a univocal source of boron has so far not been recognized. In this work, we present and discuss new Geochemical and isotopic data related to an extensive campaign (June 2016) carried out in 33 domestic well and piezometer waters. In addition, the results from a three-weekly to monthly monitoring Survey (from August 2014 to December 2019) on selected waters were used to recognize signals in response to dry and wet periods or related to the presence of the recently installed hydraulic barrier. To verify the efficiency of the hydraulic barrier a numerical model of the shallow aquifer was performed by using the MODFLOW computer program. This study has allowed to identify where the source of contamination is likely located. This implies that specific investigations can now be carried out to definitively remove the anthropogenic source of boron.

  • Geochemical Survey of the colpitas taapaca volcanic hydrothermal system northern chile
    Bollettino Della Societa Geologica Italiana, 2020
    Co-Authors: Manuel Inostroza, Franco Tassi, Jose Pablo Sepulveda, Francesco Capecchiacci, Andrea Rizzo, Felipe Aguilera
    Abstract:

    This work presents chemical and isotopic (δ13C-CO2, δ13C-CH4, 3He, 4He, 20Ne, 40Ar, 36Ar, δ18O and δD) data of fluid discharges from Colpitas-Taapaca volcanic-hydrothermal system, located close to the Taapaca Volcanic Complex, with the aim to investigate the physical-chemical conditions of the fluid source and to provide a preliminary evaluation of the geothermic potential of the study area. Colpitas thermal springs (to 56 °C) and part of the cold springs (≤18°C) from this area have a Na+-Cl- composition and Total Dissolved Solids (TDS) values (from 6,059 to 19,118 mg/L). Putre springs also show a Na +-Cl -composition, TDS values up to 7,887 mg/L, and outlet temperatures from 21 to 31 °C. Colpitas cold springs, with a Ca2+-SO42- composition and relatively low TDS values (≤1,350 mg/L), are likely produced by interaction of shallow water with uprising H2S- rich hydrothermal gases. This process is likely also controlling the chemistry of Jurase thermal springs, which have the highest outlet temperatures of the study area (up to 68 °C), a Ca2+-SO42- composition and TDS values ≤2,355 mg/L. Eventually, Las Cuevas springs have temperatures up to 36 °C, a Na+-HCO3- composition and low TDS values (≤1,067 mg/L), typical features of springs related to a shallow aquifer. The δ18O-H2O and δD-H2O values indicate that all waters have a dominant meteoric origin. Enrichments in 18O and D shown by Colpitas and Putre thermal waters are likely due to steam loss and water- rock interaction, masking a possible direct steam contribution from magmatic degassing. Gas emissions from Colpitas bubbling pools are dominated by CO2, with significant concentrations of CH4, H2S and H2. The Rc/Ra values (up to 2.04) of Colpitas gases indicate a significant contribution of magmatic to mantle He, whereas the high CO2/ 3He ratios, combined with d 13C-CO2 values ranging from -7.66 to -5.63 ‰ vs. PDB, imply a dominant crustal CO2 source, mostly involving limestone. Estimated temperatures based on the composition of waters and gases from Colpitas are up to 215 °C. Higher temperatures (240 °C) are estimated for Putre thermal waters, although these waters, as well as those from Jurase and Las Cuevas, are too immature for a reliable application of geothermometric techniques. Based on the theoretical reservoir temperature and the measured Cl total output, the thermal energy released from Colpitas thermal area is estimated at up to 13.9 Mw. Such results suggest the occurrence of a promising heat source, possibly related to Taapaca volcanic complex, and encourage the development of future research based on combined geophysical and Geochemical approaches, in order to provide a reliable evaluation of the geothermal potential of the whole area.

  • the domuyo volcanic system an enormous geothermal resource in argentine patagonia
    Journal of Volcanology and Geothermal Research, 2014
    Co-Authors: G Chiodini, Orlando Vaselli, Franco Tassi, Caterina Liccioli, Sergio Calabrese, S Caliro, Alberto T Caselli, Mariano Agusto, W Dalessandro
    Abstract:

    Abstract A Geochemical Survey of the main thermal waters discharging in the southwestern part of the Domuyo volcanic complex (Argentina), where the latest volcanic activity dates to 0.11 Ma, has highlighted the extraordinarily high heat loss from this remote site in Patagonia. The thermal water discharges are mostly Na-Cl in composition and have TDS values up to 3.78 g L− 1 (El Humazo). A simple hydroGeochemical approach shows that 1,100 to 1,300 kg s− 1 of boiling waters, which have been affected by shallow steam separation, flow into the main drainage of the area (Rio Varvarco). A dramatic increase of the most conservative species such as Na, Cl and Li from the Rio Varvarco from upstream to downstream was observed and related solely to the contribution of hydrothermal fluids. The equilibrium temperatures of the discharging thermal fluids, calculated on the basis of the Na-K-Mg geothermometer, are between 190 °C and 230 °C. If we refer to a liquid originally at 220 °C (enthalpy = 944 J g− 1), the thermal energy release can be estimated as high as 1.1 ± 0.2 GW, a value that is much higher than the natural release of heat in other important geothermal fields worldwide, e.g., Mutnovsky (Russia), Wairakei (New Zealand) and Lassen Peak (USA). This value is the second highest measured advective heat flux from any hydrothermal system on Earth after Yellowstone.

  • distribution of gaseous hg in the mercury mining district of mt amiata central italy a Geochemical Survey prior the reclamation project
    Environmental Research, 2013
    Co-Authors: Orlando Vaselli, Pablo Higueras, Barbara Nisi, Jose Maria Esbri, Jacopo Cabassi, Alba Martinezcoronado, Franco Tassi, Daniele Rappuoli
    Abstract:

    Abstract The Mt. Amiata volcano is the youngest and largest volcanic edifice in Tuscany (central-northern Italy) and is characterized by a geothermal field, exploited for the production of electrical energy. In the past Mt. Amiata was also known as a world-class Hg district whose mining activity was mainly distributed in the central-eastern part of this silicic volcanic complex, and particularly in the municipality of Abbadia San Salvatore. In the present work we report a Geochemical Survey on Hg0 measurements related to the former mercury mine facilities prior the reclamation project. The Hg0 measurements were carried out by car for long distance regional Surveys, and on foot for local scale Surveys by using two LUMEX (915+ and M) devices. This study presents the very first Hg0 data obtained with this analytical technique in the Mt. Amiata area. The facilities related to the mining areas and structures where cinnabar was converted to metallic Hg are characterized by high Hg values (>50,000 ng m−3), although the urban center of Abbadia San Salvatore, few hundred meters away, does not appear to be receiving significant pollution from the calcine area and former industrial edifices, all the recorded values being below the values recommended by the issuing Tuscany Region authorities (300 ng m−3) and in some cases approaching the Hg background levels (3–5 ng m−3) for the Mt. Amiata area.

  • gas discharges from four remote volcanoes in northern chile putana olca irruputuncu and alitar a Geochemical Survey
    Annals of Geophysics, 2011
    Co-Authors: Franco Tassi, Orlando Vaselli, Felipe Aguilera, Thomas H Darrah, Eduardo Medina
    Abstract:

    We analyzed gas samples collected from fumaroles and bubbling pools at Irruputuncu, Putana, Olca and Alitar volcanoes located in the central Andes volcanic zone (northern Chile). The Irruputuncu and Putana fumarolic discharges showed outlet temperatures ranging from 83 ˚C to 240 ˚C and from 82 ˚C to 88 ˚C, respectively. The chemical and isotopic ( 3 He/ 4 He, d 13 C-CO 2 , d 18 O-H 2 O and dD-H 2 O) compositions of these discharges were similar to medium-to-high temperature volcanic gases from other active volcanoes in this sector of the Andean volcanic chain (e.g. Lascar volcano). Inorganic and organic gas geothermometers for the H 2 O-CO 2 -CO-H 2 , CO 2 -CH 4 and C 2 -C 3 alkenes-alkanes systems indicated equilibrium temperatures that exceed 500 ˚C at the gas sources. These relatively high temperatures are in agreement with the presence of relevantly high concentrations of magmatic gas emissions, including SO 2 . Olca and Alitar volcano fluid chemistries indicated lower amounts of magmatic-derived gas species, while both the helium and the water isotopic compositions suggested significant fractions of shallow, crustal/meteoric-originated fluids. These indicate contributions from a hydrothermal environment with temperatures <400 ˚C. The Geochemical and isotopic features derived from the present study show that the Irruputuncu, Putana, Olca and Alitar volcanoes should be considered as active and thus warrant periodic Geochemical monitoring to determine the evolution of these systems and their potential hazards.

David B Smith - One of the best experts on this subject based on the ideXlab platform.

  • the potential of mid and near infrared diffuse reflectance spectroscopy for determining major and trace element concentrations in soils from a Geochemical Survey of north america
    Applied Geochemistry, 2009
    Co-Authors: James B Reeves, David B Smith
    Abstract:

    Abstract In 2004, soils were collected at 220 sites along two transects across the USA and Canada as a pilot study for a planned soil Geochemical Survey of North America (North American Soil Geochemical Landscapes Project). The objective of the current study was to examine the potential of diffuse reflectance (DR) Fourier Transform (FT) mid-infrared (mid-IR) and near-infrared (NIRS) spectroscopy to reduce the need for conventional analysis for the determination of major and trace elements in such continental-scale Surveys. Soil samples ( n  = 720) were collected from two transects (east–west across the USA, and north–south from Manitoba, Canada to El Paso, Texas (USA), n  = 453 and 267, respectively). The samples came from 19 USA states and the province of Manitoba in Canada. They represented 31 types of land use (e.g., national forest, rangeland, etc.), and 123 different land covers (e.g., soybeans, oak forest, etc.). The samples represented a combination of depth-based sampling (0–5 cm) and horizon-based sampling (O, A and C horizons) with 123 different depths identified. The set was very diverse with few samples similar in land use, land cover, etc. All samples were analyzed by conventional means for the near-total concentration of 49 analytes (C total , C carbonate and C organic , and 46 major and trace elements). Spectra were obtained using dried, ground samples using a Digilab FTS-7000 FT spectrometer in the mid- (4000–400 cm −1 ) and near-infrared (10,000–4000 cm −1 ) at 4 cm −1 resolution (64 co-added scans per spectrum) using a Pike AutoDIFF DR autosampler. Partial least squares calibrations were develop using: (1) all samples as a calibration set; (2) samples evenly divided into calibration and validation sets based on spectral diversity; and (3) samples divided to have matching analyte concentrations in calibration and validation sets. In general, results supported the conclusion that neither mid-IR nor NIRS would be particularly useful in reducing the need for conventional analysis of soils from this continental-scale Geochemical Survey. The extreme sample diversity, likely caused by the widely varied parent material, land use at the site of collection (e.g., grazing, recreation, agriculture, etc.), and climate resulted in poor calibrations even for C total , C organic and C carbonate . The results indicated potential for mid-IR and NIRS to differentiate soils containing high concentrations (>100 mg/kg) of some metals (e.g., Co, Cr, Ni) from low-level samples (

  • pilot studies for the north american soil Geochemical landscapes project site selection sampling protocols analytical methods and quality control protocols
    Applied Geochemistry, 2009
    Co-Authors: David B Smith, Laurel G Woodruff, Richard M Oleary, William F Cannon, Robert G Garrett, James E Kilburn, Martin B Goldhaber
    Abstract:

    In 2004, the US Geological Survey (USGS) and the Geological Survey of Canada sampled and chemically analyzed soils along two transects across Canada and the USA in preparation for a planned soil Geochemical Survey of North America. This effort was a pilot study to test and refine sampling protocols, analytical methods, quality control protocols, and field logistics for the continental Survey. A total of 220 sample sites were selected at approximately 40-km intervals along the two transects. The ideal sampling protocol at each site called for a sample from a depth of 0–5 cm and a composite of each of the O, A, and C horizons. The <2-mm fraction of each sample was analyzed for Al, Ca, Fe, K, Mg, Na, S, Ti, Ag, As, Ba, Be, Bi, Cd, Ce, Co, Cr, Cs, Cu, Ga, In, La, Li, Mn, Mo, Nb, Ni, P, Pb, Rb, Sb, Sc, Sn, Sr, Te, Th, Tl, U, V, W, Y, and Zn by inductively coupled plasma-mass spectrometry and inductively coupled plasma-atomic emission spectrometry following a near-total digestion in a mixture of HCl, HNO3, HClO4, and HF. Separate methods were used for Hg, Se, total C, and carbonate-C on this same size fraction. Only Ag, In, and Te had a large percentage of concentrations below the detection limit. Quality control (QC) of the analyses was monitored at three levels: the laboratory performing the analysis, the USGS QC officer, and the principal investigator for the study. This level of review resulted in an average of one QC sample for every 20 field samples, which proved to be minimally adequate for such a large-scale Survey. Additional QC samples should be added to monitor within-batch quality to the extent that no more than 10 samples are analyzed between a QC sample. Only Cr (77%), Y (82%), and Sb (80%) fell outside the acceptable limits of accuracy (% recovery between 85 and 115%) because of likely residence in mineral phases resistant to the acid digestion. A separate sample of 0–5-cm material was collected at each site for determination of organic compounds. A subset of 73 of these samples was analyzed for a suite of 19 organochlorine pesticides by gas chromatography. Only three of these samples had detectable pesticide concentrations. A separate sample of A-horizon soil was collected for microbial characterization by phospholipid fatty acid analysis (PLFA), soil enzyme assays, and determination of selected human and agricultural pathogens. Collection, preservation and analysis of samples for both organic compounds and microbial characterization add a great degree of complication to the sampling and preservation protocols and a significant increase to the cost for a continental-scale Survey. Both these issues must be considered carefully prior to adopting these parameters as part of the soil Geochemical Survey of North America. Published by Elsevier Ltd.