Browsing by Autor "Laurence Maurice"

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Beyond cadmium accumulation: Distribution of other trace elements in soils and cacao beans in Ecuador
(Elsevier BV, 2020) Fiorella Barraza; Eva Schreck; Gaëlle Uzu; Thibaut Lévèque; Cyril Zouiten; Mathieu Boidot; Laurence Maurice
Changes in the occurrence of heavy metals in the tropical atmosphere during the past 22,000 years as recorded in Bolivian ice core
(Springer Science+Business Media, 2003) Sungmin Hong; J. K. Park; Lonnie G. Thompson; C.F. Boutron; Christophe Ferrari; Bruno Franco; Laurence Maurice
Nine sections from the Sajama ice core recovered from the summit of an extinct Andean volcano in Bolivia were analysed for various heavy metals to assess anthropogenic changes in the tropical upper troposphere over South America. These samples include two sections dating from 14100 to 19200 years BP, corresponding to the Last Glacial Stage (LGS), one section dating from 2800 years BP (the late Holocene), and six sections dating from AD 790 to 1988. The preliminary data, combined with data reported elsewhere, demonstrate that the heavy metal concentrations since the late Holocene are higher than in the period from the LGS to the early Holocene. The enrichment factors calculated by normalizing for crustal abundance using the metal/Al ratio in the mean upper continental crust indicate that a significant input of heavy metals attributed to anthropogenic contributions has occurred since the beginning of the 19th century for Pb and from the last century for Cd, Cu, and Zn.
Childhood lead exposure of Amerindian communities in French Guiana: an isotopic approach to tracing sources
(2021) Laurence Maurice; Fiorella Barraza; Isalyne Blondet; Michèle Ho-A-Chuck; Jessy Tablon; Paul Brousse; Magalie Demar; Eva Schreck
Concentrations and stable isotopes of mercury in sharks of the Galapagos Marine Reserve: Human health concerns and feeding patterns
(2021) Laurence Maurice; Gaël Le Croizier; Gabriela Morales; Natalia Carpintero; Juan M. Guayasamin; Jeroen E. Sonke; Diego Páez‐Rosas; David Point; Walter Bustos; Valeria Ochoa‐Herrera
The human ingestion of mercury (Hg) from sea food is of big concern worldwide due to adverse health effects, and more specifically if shark consumption constitutes a regular part of the human diet. In this study, the total mercury (THg) concentration in muscle tissue were determined in six sympatric shark species found in a fishing vessel seized in the Galapagos Marine Reserve in 2017. The THg concentrations in shark muscle samples (n = 73) varied from 0.73 mg kg-1 in bigeye thresher sharks (Alopias superciliosus) to 8.29 mg kg-1 in silky sharks (Carcharhinus falciformis). A typical pattern of Hg bioaccumulation was observed for all shark species, with significant correlation between THg concentration and shark size for bigeye thresher sharks, pelagic thresher sharks (Alopias pelagicus) and silky sharks. Regarding human health concerns, the THg mean concentration exceeded the maximum weekly intake fish serving in all the studied species. Mass-Dependent Fractionation (MDF, δ202Hg values) and Mass-Independent Fractionation (MIF, Δ199Hg values) of Hg in whitetip sharks (Carcharhinus longimanus) and silky sharks, ranged from 0.70‰ to 1.08‰, and from 1.97‰ to 2.89‰, respectively. These high values suggest that both species are feeding in the epipelagic zone (i.e. upper 200 m of the water column). While, blue sharks (Prionace glauca), scalloped hammerhead sharks (Shyrna lewini) and thresher sharks were characterized by lower Δ199Hg and δ202Hg values, indicating that these species may focus their foraging behavior on prey of mesopelagic zone (i.e. between 200 and 1000 m depth). In conclusion, the determination of THg concentration provides straight-forward evidence of the human health risks associated with shark consumption, while mercury isotopic compositions constitute a powerful tool to trace the foraging strategies of these marine predators. CAPSULE: A double approach combining Hg concentrations with stable isotopes ratios allowed to assess ontogeny in common shark species in the area of the Galapagos Marine Reserve and the human health risks concern associated to their consumption.
CONTAMINACION POR MERCURIO EN AGUA, PECES Y CABELLOS HUMANOS DEBIDO A LA MINERÍA AURÍFERA EN LA CUENCA AMAZÓNICA BOLIVIANA
(2013) Laurence Maurice; Irma Lucía Jaramillo Quiroga; Olaf Malm; J. Chincheros
MERCURY CONTAMINATION IN WATER, FISH AND HUMAN HAIR AS A RESULT OF GOLD MINING IN THE AMAZONIAN BASIN OF BOLIVIA Se presentan los primeros resultados sobre el contenido en mercurio en dos compartimentos bioticos (peces y cabellos humanos) de la cuenca Amazonica Boliviana con un en foque mas preciso en el area minera de los tributarios del rio Beni. Las concentraciones en mercurio analizado en los peces piscivoros varian en los rios Beni y Mamore desde 0.3-2.3 pg Hg g-1 y 0.4-2.1 pg Hg g- 1 respectivamente, a 0.3-5.2 pg Hg g-1 en la cabecera de! rio Madera. Los resultados mostraron que el 70% de los peces piscivoros colectados estan altamente contaminados ya que sobrepasan, hasta cinco veces, el valor limite de la OMS (1976) de 0.5 pg Hg g-1. El mercurio acumulado en los peces piscivoros esta principalmente en forma organica; el metilmercurio representa 70 a 100% del mercurio total. Los resultados tambien muestran que el mayor impacto del mercurio se manifiesta sobre la salud de la poblacion que no trabaja directamente en actividades auriferas, pero que se alimenta regularmente de pescado. Palabras clave: Mercurio, Cabellos humanos, Peces, Cuenca amazonica, Bolivia. ABSTRACT First results on the mercury concentration in twa biotic compartments (fish and human hair) from the goid mining area of the Bolivian Amazonian basin, SW Amazon, are presented. The mercury concentrations found in carnivorous fishes vary in the Beni River from 0.3 to 2.3 pg Hg g-1, in the Mamore River, from 0.4 to 2.1 pg Hg g-1, and in the Madeira River at its formation from 0.3 to 5.2 pg Hg g-i. This results indicate, on bne hand, that 70% of the piscivorous fishes collected is contaminated and on the other hand, that high mercury concentrations can nearly exceed 5 times the WHO (1976) safety limit (0.5 pg Hg g-l). The mercury accumulated by carnivorous fishes is mainly present on its organic form effectively, methylmercury represents 70 fo 100% of the total mercury analysed. Our results show that the major health impact caused by mercury affects people who are not working directly in gold cooperatives but who have a fish diet. Key words: Mercury, Human hair, Fish, Amazonian basin, Bolivia
Determination of the Microbial and Chemical Loads in Rivers from the Quito Capital Province of Ecuador (Pichincha)—A Preliminary Analysis of Microbial and Chemical Quality of the Main Rivers
(Multidisciplinary Digital Publishing Institute, 2020) Pamela Borja-Serrano; Valeria Ochoa‐Herrera; Laurence Maurice; Gabriela Morales; Cristian Quilumbaqui; Eduardo Tejera; António Machado
Contamination of natural water sources is one of the main health problems worldwide, which could be caused by chemicals, metals, or microbial agents. This study aimed to analyze the quality of 18 rivers located in Quito, the capital province of Pichincha, Ecuador, through physico-chemical and microbial parameters. The E. coli and total coliforms assessments were performed by a counting procedure in growth media. Polymerase chain reaction (PCR) was realized to detect several microbial genera, as well as Candida albicans, two parasites (Cryptosporidium and Giardia spp.) and E. coli pathotypes: enterohemorrhagic E. coli (EHEC), enteroaggregative E. coli (EAEC), enteroinvasive E. coli (EIEC) and enteropathogenic E. coli (EPEC). Additionally, physico-chemical parameters and major and trace metals were analyzed in each surface water sample. Our results demonstrated that most of the rivers analyzed do not comply with the microbial, physico-chemical, and metal requirements established by the Ecuadorian legislation. In terms of microbial pollution, the most polluted rivers were Monjas, Machángara, Pisque, and Pita Rivers. Furthermore, three out of four analyzed E. coli pathotypes (EIEC, EHEC, and EAEC) were detected in certain rivers, specifically: Monjas River showed the presence of EIEC and EHEC; in the Machángara River, EAEC and EIEC were detected; and finally, EIEC was present in the Guayllabamba River. Several physico-chemical parameters, such as pH, CODtotal, and TSS values, were higher than the Ecuadorian guidelines in 11, 28, and 28% of the rivers, respectively. Regarding heavy metals, Zn, Cu, Ni, Pb, Cd, and Mn surpassed the established values in 94, 89, 61, 22, 22, and 17% of the rivers, respectively. Machangara River was the only one that registered higher Cr concentrations than the national guidelines. The values of Al and Fe were above the recommended values in 83 and 72% of the rivers. Overall, based on the physical-chemical and microbiological parameters the most contaminated rivers were Machángara and Monjas. This study revealed severe contaminations in Ecuadorean Rivers; further studies should evaluate the sources of contamination and their impact on public health.
Determining the microbial and chemical contamination in Ecuador’s main rivers
(Nature Portfolio, 2021) Dayana Vinueza; Valeria Ochoa‐Herrera; Laurence Maurice; Eduardo Tamayo; Lorena Mejía; Eduardo Tejera; António Machado
Distribution, contents and health risk assessment of metal(loid)s in small-scale farms in the Ecuadorian Amazon: An insight into impacts of oil activities
(Elsevier BV, 2017) Fiorella Barraza; Laurence Maurice; Gaëlle Uzu; Sylvia Becerra; Fausto López; Valeria Ochoa‐Herrera; Jenny Ruales; Eva Schreck
Drinking water quality in areas impacted by oil activities in Ecuador: Associated health risks and social perception of human exposure
(Elsevier BV, 2019) Laurence Maurice; Fausto López; Sylvia Becerra; Hala Jamhoury; Karyn Le Ménach; Marie‐Hélène Devier; Hélène Budzinski; Jonathan Prunier; Guilhem Juteau-Martineau; Valeria Ochoa‐Herrera
Heavy metals in ancient tropical ice: initial results
(Elsevier BV, 2001) Christophe Ferrari; Thomas Clotteau; Lonnie G. Thompson; Carlo Barbante; Giulio Cozzi; Paolo Cescon; Sungmin Hong; Laurence Maurice; Bernard Francou; Claude F. Boutron
Hg Speciation and Stable Isotope Signatures in Human Hair As a Tracer for Dietary and Occupational Exposure to Mercury
(American Chemical Society, 2011) Laure Laffont; Jeroen E. Sonke; Laurence Maurice; Selma Luna-Monrroy; J. Chincheros; David Amouroux; Philippe Behra
Exposure of humans and wildlife to various inorganic and organometallic forms of mercury (Hg) may induce adverse health effects. While human populations in developed countries are mainly exposed to marine fish monomethylmercury (MMHg), this is not necessarily the case for developing countries and diverse indigenous people. Identification of Hg exposure sources from biomonitor media such as urine or hair would be useful in combating exposure. Here we report on the Hg stable isotope signatures and Hg speciation in human hair across different gold miner, indigenous and urban populations in Bolivia and France. We found evidence for both mass-dependent isotope fractionation (MDF) and mass-independent isotope fractionation (MIF) in all hair samples. Three limiting cases of dominant exposure to inorganic Hg (IHg), freshwater fish MMHg, and marine fish MMHg sources are used to define approximate Hg isotope source signatures. Knowing the source signatures, we then estimated Hg exposure sources for the Bolivian gold miner populations. Modeled IHg levels in hair correspond well to measured IHg concentrations (R = 0.9), demonstrating that IHg exposure sources to gold miners can be monitored in hair samples following either its chemical speciation or isotopic composition. Different MMHg and inorganic exposure levels among gold miners appear to correspond to living and working conditions, including proximity to small towns, and artisanal vs large scale mining activity.
Mercury distribution in waters and fishes of the upper Madeira rivers and mercury exposure in riparian Amazonian populations
(Elsevier BV, 2000) Laurence Maurice
Pb and Sr isotopes from an ice-core provides evidence for changing atmospheric conditions at the Sajama icecap, South America
(Springer Science+Business Media, 2003) K. J.R. Roman; Sang-Bum Hong; G. Bulion; Laurie J. Burn; C.F. Boutron; Christophe Ferrari; Lonnie G. Thompson; Laurence Maurice; Bernard Francou
Measurements of Pb and Sr isotopes and Pb, Sr, Ba and Rb concentrations in ice-core samples from the Sajama icecap in Bolivia were made to investigate the changing environmental conditions in the region over the past 22 ky.. The Pb isotopic measurements indicate there has been a significant change in the 206 Pb/ 207 Pb ratio in the ice by 1700 AD which can be attributed to human activity. This change was also accompanied by increasing Pb/Ba ratios that reach ∼10 times natural values by the beginning of the 20 th century, confirming an increase of anthropogenic Pb levels. Sr and Rb concentrations are highly enhanced in 3 ky and 0.5 ky BP ice relative to the upper-crustal rock indicating a different origin for a significant proportion of the dust in these samples. Likely sources of this dust are dry lake beds that occur on the Altiplano as a result of changing climatic conditions. This dust adds to the background level of dust accumulating on the Sajama icecap.
Sources of mercury in surface waters of the upper Madeira erosive basins, Bolivia
(Springer Science+Business Media, 2003) Laurence Maurice; L. Alanoca; Pascal Fraizy; Philippe Vauchel
The human activities impact on the mercury (Hg) distribution in the Amazon waters is still discussed but very few information regarding the Hg sources from the highly turbid Andean headwaters have been published. The annual load of suspended sediments eroded from the Bolivian Andes, averages 300x10 6 tons in the Beni river, of which till 97% is exported during the rainy season. At the edge of the Bolivian Andean piedmont, the total Hg concentration vary from 8 ng/l during the dry season, to 1600 ng/l during the high water period. During this stage, it appears that the maximum concentrations of Hg associated with the fine particles and the highest Hg specific fluxes are observed in the rivers exploited for their alluvial gold during the last century. The black-shales series associated to the gold deposits are characterised by high natural Hg contents, which can be released in the hydrographic system by both chemical and physical weathering. But if we compare two clear water rivers characterised by the same suspended sediment concentrations, the maximum specific Hg flux varies between 126 kg/km 2 .j in the pristine river, to 590 kg/km 2 .j in the river characterised by recent human activities.
Weathering and transport of sediments in the Bolivian Andes: Time constraints from uranium-series isotopes
(Elsevier BV, 2006) Anthony Dosseto; Bernard Bourdon; Jérôme Gaillardet; Laurence Maurice; Claude J. Allègre