Avaliação de risco à saúde humana por contaminação natural de arsênio nas águas subterrâneas e nos solos da área urbana de Ouro Preto (MG)

This study was performed so as to make an assessment of human exposure to natural contamination by arsenic (As) in groundwaters and soils in the urban area of Ouro Preto, MG), Brazil, specifically in the Piedade, Taquaral, Padre Faria, Alto da Cruz, Antônio Dias, and Barra neighborhoods. In this study, the following items were estimated for the children and adult residents in these locations: (i) the values of daily ingested doses (DID) of As; (ii) the values for risk quotients (QRs) and (iii) the increase of the probability of developing cancer throughout life (RC), with mean content of As found in groundwaters varying from 10 to 77 µg.L-1 and, in the soils, from 332.75 to 656 mg.kg-1.Na avaliação da exposição humana à contaminação natural por arsênio (As) das águas subterrâneas e solos na área urbana da cidade de Ouro Preto, MG), nos bairros Piedade, Taquaral, Padre Faria, Alto da Cruz, Antônio Dias e Barra, foram estimados, para as crianças e adultos residentes nesses locais: (i) os valores das doses de ingestão diárias (DID) de As; (ii) os valores para os quocientes de risco (QRs) e (iii) o incremento da probabilidade de se desenvolver câncer ao longo da vida (RC), com teores médios de As encontrados nas águas subterrâneas, variando entre 10 e 77 µg.L-1 e, nos solos, de 332,75 e 656 mg.kg-1

Anthropogenic influence on the degradation of an urban lake ? the Pampulha reservoir in Belo Horizonte, Minas Gerais, Brazil.

The artificial reservoir Lagoa da Pampulha in central Brazil has been increasingly affected by sediment deposition and pollution from urban and industrial sources. This study investigates water chemistry and heavy metal concentrations and their fractionation in the lake sediment using ICP-OES, ICP-MS, and XRD analyses. Fractionation analysis was done by sequential extraction under inert gas as well as after oxidation. The lake exhibits a permanent stratification with an oxygen-free hypolimnion below 2mdepth. Nutrient concentrations are enriched for phosphorous components (SRP,PO4). In the sediment it was not possible to detect oxygen. Carbon, sulfur, and most of the analyzed heavy metals are enriched in the top sediment layer with a pronounced down ward decrease, indicating the presence of an anthropogenic influence. Statistic alanalysis, including correlations and a Principal Component Analysis (PCA) of depth-related total concentration data, helps to distinguish presumably anthropogenic heavy metals from geogenic components. Some samples with high element concentrations in the sediment also show elevated concentrations in their pore water. Analyses of element distribution between sediment and pore water suggest a strong bonding of heavy metals to the anoxic sediment. The trend to wards elevated solubility in the pore water of oxidized samples is clear for most of the analyzed elements. Fractionation analysis reveals characteristic associations of selected elements to specific mineral bonding forms. In addition, it indicates that the behavior of heavy metals in the sediment is strongly influenced by organic substances. These substances provide buffering against oxidation, acidification, and metal release. The high nutrient loading causes reducing conditions in the lake sediment. These conditions trigger the accumulation of sediments rich in S2, which stabilizes the fixation of heavy elements. In the future, care must be taken to reduce the supply of contaminants and to prevent the release of heavy metals from sediments dredged for remediation purposes

Quantification of methylmercury and geochemistry of mercury in sediments from a contaminated area of Descoberto (MG), Brazil.

In 2002, metallic Hg was found buried in a rural area of Descoberto city, Brazil. The origin of the Hg was a gold mining explotation plant established nearly one century ago. Although a number of studies have been conducted in order to assess the contamination of the area, none of them investigated the presence of methylated Hg in the hydric system. In this work methylmercury (CH3Hg?) was determined using gas chromatography-pyrolysis-atomic fluorescence detection (CG-pyro-AFS) in material from rain sedimentation boxes and stream sediments near the contaminated area. Total Hg concentration (HgT) along with the chemical speciation by thermo-desorption were performed. HgT in material from the sedimentation boxes was found to be very high, up to 41,580 mg kg 1, even in the rainy season, when in general HgT were much lower than in dry season. The samples from the Grama and Rico streams show a range of HgT from 5.8 to 266 mg kg 1. The thermo-desorption analysis showed predominance of Hg2?, possibly linked to organic sulfur, suggested by a good positive correlation between Hg2?, HgT, organic mater (OM) and total S. The CH3Hg? concentration in stream sediment samples ranged from <0.07 to 1.87 mg kg 1 and in the samples of sedimentation boxes the concentrations were 1.33 and 8.0 mg kg 1 during dry season. The sample with the highest percentage of HgT as Hg2? (98%) presented also the highest percentage of CH3Hg? (0.7%). These are high values, showing that care should be taken to avoid the transport of this material to the hydrological system. Further studies on the transfer through the food chain would be very important

Evaluation of matrix effect on the determination of rare earth elements and As, Bi, Cd, Pb, Se and In in honey and pollen of native Brazilian bees (Tetragonisca angustula ? Jata?) by Q-ICP-MS.

Bees are considered the main pollinators in natural and agricultural environments. Chemical elements from honey and pollen have been used for monitoring the environment, the health of bees and the quality of their products. Nevertheless, there are not many studies on honey and pollen of native Brazilian bees. The goal of this work was to determine important chemical elements (Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Lu and Yb) along with As, Bi, Cd, Pb, Se and In, in honey and pollen of native Brazilian bees, assessing analytical interferences from the matrix. A proposed analytical method was developed for these elements by quadrupole ICP-MS. Matrix effect was verified in honey matrix in the quantification of As, Bi and Dy; and in pollen matrix for Bi, Cd, Ce, Gd, La, Pb and Sc. The quality of the method was considered satisfactory taking into consideration the recovery rate of each element in the spiked solutions: honey matrix (91.6?103.9%) and pollen matrix (94.1?115.6%). The quantification limits of the method ranged between 0.00041 and 10.3 ?g L?1 for honey and 0.00041?0.095 ?g L?1 for pollen. The results demonstrate that the method is accurate, precise and suitable

Human Practice. Digital Ecologies. Our Future. : 14. Internationale Tagung Wirtschaftsinformatik (WI 2019) : Tagungsband

Erschienen bei: universi - Universitätsverlag Siegen. - ISBN: 978-3-96182-063-4Aus dem Inhalt: Track 1: Produktion & Cyber-Physische Systeme Requirements and a Meta Model for Exchanging Additive Manufacturing Capacities Service Systems, Smart Service Systems and Cyber- Physical Systems—What’s the difference? Towards a Unified Terminology Developing an Industrial IoT Platform – Trade-off between Horizontal and Vertical Approaches Machine Learning und Complex Event Processing: Effiziente Echtzeitauswertung am Beispiel Smart Factory Sensor retrofit for a coffee machine as condition monitoring and predictive maintenance use case Stakeholder-Analyse zum Einsatz IIoT-basierter Frischeinformationen in der Lebensmittelindustrie Towards a Framework for Predictive Maintenance Strategies in Mechanical Engineering - A Method-Oriented Literature Analysis Development of a matching platform for the requirement-oriented selection of cyber physical systems for SMEs Track 2: Logistic Analytics An Empirical Study of Customers’ Behavioral Intention to Use Ridepooling Services – An Extension of the Technology Acceptance Model Modeling Delay Propagation and Transmission in Railway Networks What is the impact of company specific adjustments on the acceptance and diffusion of logistic standards? Robust Route Planning in Intermodal Urban Traffic Track 3: Unternehmensmodellierung & Informationssystemgestaltung (Enterprise Modelling & Information Systems Design) Work System Modeling Method with Different Levels of Specificity and Rigor for Different Stakeholder Purposes Resolving Inconsistencies in Declarative Process Models based on Culpability Measurement Strategic Analysis in the Realm of Enterprise Modeling – On the Example of Blockchain-Based Initiatives for the Electricity Sector Zwischenbetriebliche Integration in der Möbelbranche: Konfigurationen und Einflussfaktoren Novices’ Quality Perceptions and the Acceptance of Process Modeling Grammars Entwicklung einer Definition für Social Business Objects (SBO) zur Modellierung von Unternehmensinformationen Designing a Reference Model for Digital Product Configurators Terminology for Evolving Design Artifacts Business Role-Object Specification: A Language for Behavior-aware Structural Modeling of Business Objects Generating Smart Glasses-based Information Systems with BPMN4SGA: A BPMN Extension for Smart Glasses Applications Using Blockchain in Peer-to-Peer Carsharing to Build Trust in the Sharing Economy Testing in Big Data: An Architecture Pattern for a Development Environment for Innovative, Integrated and Robust Applications Track 4: Lern- und Wissensmanagement (e-Learning and Knowledge Management) eGovernment Competences revisited – A Literature Review on necessary Competences in a Digitalized Public Sector Say Hello to Your New Automated Tutor – A Structured Literature Review on Pedagogical Conversational Agents Teaching the Digital Transformation of Business Processes: Design of a Simulation Game for Information Systems Education Conceptualizing Immersion for Individual Learning in Virtual Reality Designing a Flipped Classroom Course – a Process Model The Influence of Risk-Taking on Knowledge Exchange and Combination Gamified Feedback durch Avatare im Mobile Learning Alexa, Can You Help Me Solve That Problem? - Understanding the Value of Smart Personal Assistants as Tutors for Complex Problem Tasks Track 5: Data Science & Business Analytics Matching with Bundle Preferences: Tradeoff between Fairness and Truthfulness Applied image recognition: guidelines for using deep learning models in practice Yield Prognosis for the Agrarian Management of Vineyards using Deep Learning for Object Counting Reading Between the Lines of Qualitative Data – How to Detect Hidden Structure Based on Codes Online Auctions with Dual-Threshold Algorithms: An Experimental Study and Practical Evaluation Design Features of Non-Financial Reward Programs for Online Reviews: Evaluation based on Google Maps Data Topic Embeddings – A New Approach to Classify Very Short Documents Based on Predefined Topics Leveraging Unstructured Image Data for Product Quality Improvement Decision Support for Real Estate Investors: Improving Real Estate Valuation with 3D City Models and Points of Interest Knowledge Discovery from CVs: A Topic Modeling Procedure Online Product Descriptions – Boost for your Sales? Entscheidungsunterstützung durch historienbasierte Dienstreihenfolgeplanung mit Pattern A Semi-Automated Approach for Generating Online Review Templates Machine Learning goes Measure Management: Leveraging Anomaly Detection and Parts Search to Improve Product-Cost Optimization Bedeutung von Predictive Analytics für den theoretischen Erkenntnisgewinn in der IS-Forschung Track 6: Digitale Transformation und Dienstleistungen Heuristic Theorizing in Software Development: Deriving Design Principles for Smart Glasses-based Systems Mirroring E-service for Brick and Mortar Retail: An Assessment and Survey Taxonomy of Digital Platforms: A Platform Architecture Perspective Value of Star Players in the Digital Age Local Shopping Platforms – Harnessing Locational Advantages for the Digital Transformation of Local Retail Outlets: A Content Analysis A Socio-Technical Approach to Manage Analytics-as-a-Service – Results of an Action Design Research Project Characterizing Approaches to Digital Transformation: Development of a Taxonomy of Digital Units Expectations vs. Reality – Benefits of Smart Services in the Field of Tension between Industry and Science Innovation Networks and Digital Innovation: How Organizations Use Innovation Networks in a Digitized Environment Characterising Social Reading Platforms— A Taxonomy-Based Approach to Structure the Field Less Complex than Expected – What Really Drives IT Consulting Value Modularity Canvas – A Framework for Visualizing Potentials of Service Modularity Towards a Conceptualization of Capabilities for Innovating Business Models in the Industrial Internet of Things A Taxonomy of Barriers to Digital Transformation Ambidexterity in Service Innovation Research: A Systematic Literature Review Design and success factors of an online solution for cross-pillar pension information Track 7: IT-Management und -Strategie A Frugal Support Structure for New Software Implementations in SMEs How to Structure a Company-wide Adoption of Big Data Analytics The Changing Roles of Innovation Actors and Organizational Antecedents in the Digital Age Bewertung des Kundennutzens von Chatbots für den Einsatz im Servicedesk Understanding the Benefits of Agile Software Development in Regulated Environments Are Employees Following the Rules? On the Effectiveness of IT Consumerization Policies Agile and Attached: The Impact of Agile Practices on Agile Team Members’ Affective Organisational Commitment The Complexity Trap – Limits of IT Flexibility for Supporting Organizational Agility in Decentralized Organizations Platform Openness: A Systematic Literature Review and Avenues for Future Research Competence, Fashion and the Case of Blockchain The Digital Platform Otto.de: A Case Study of Growth, Complexity, and Generativity Track 8: eHealth & alternde Gesellschaft Security and Privacy of Personal Health Records in Cloud Computing Environments – An Experimental Exploration of the Impact of Storage Solutions and Data Breaches Patientenintegration durch Pfadsysteme Digitalisierung in der Stressprävention – eine qualitative Interviewstudie zu Nutzenpotenzialen User Dynamics in Mental Health Forums – A Sentiment Analysis Perspective Intent and the Use of Wearables in the Workplace – A Model Development Understanding Patient Pathways in the Context of Integrated Health Care Services - Implications from a Scoping Review Understanding the Habitual Use of Wearable Activity Trackers On the Fit in Fitness Apps: Studying the Interaction of Motivational Affordances and Users’ Goal Orientations in Affecting the Benefits Gained Gamification in Health Behavior Change Support Systems - A Synthesis of Unintended Side Effects Investigating the Influence of Information Incongruity on Trust-Relations within Trilateral Healthcare Settings Track 9: Krisen- und Kontinuitätsmanagement Potentiale von IKT beim Ausfall kritischer Infrastrukturen: Erwartungen, Informationsgewinnung und Mediennutzung der Zivilbevölkerung in Deutschland Fake News Perception in Germany: A Representative Study of People’s Attitudes and Approaches to Counteract Disinformation Analyzing the Potential of Graphical Building Information for Fire Emergency Responses: Findings from a Controlled Experiment Track 10: Human-Computer Interaction Towards a Taxonomy of Platforms for Conversational Agent Design Measuring Service Encounter Satisfaction with Customer Service Chatbots using Sentiment Analysis Self-Tracking and Gamification: Analyzing the Interplay of Motivations, Usage and Motivation Fulfillment Erfolgsfaktoren von Augmented-Reality-Applikationen: Analyse von Nutzerrezensionen mit dem Review-Mining-Verfahren Designing Dynamic Decision Support for Electronic Requirements Negotiations Who is Stressed by Using ICTs? A Qualitative Comparison Analysis with the Big Five Personality Traits to Understand Technostress Walking the Middle Path: How Medium Trade-Off Exposure Leads to Higher Consumer Satisfaction in Recommender Agents Theory-Based Affordances of Utilitarian, Hedonic and Dual-Purposed Technologies: A Literature Review Eliciting Customer Preferences for Shopping Companion Apps: A Service Quality Approach The Role of Early User Participation in Discovering Software – A Case Study from the Context of Smart Glasses The Fluidity of the Self-Concept as a Framework to Explain the Motivation to Play Video Games Heart over Heels? An Empirical Analysis of the Relationship between Emotions and Review Helpfulness for Experience and Credence Goods Track 11: Information Security and Information Privacy Unfolding Concerns about Augmented Reality Technologies: A Qualitative Analysis of User Perceptions To (Psychologically) Own Data is to Protect Data: How Psychological Ownership Determines Protective Behavior in a Work and Private Context Understanding Data Protection Regulations from a Data Management Perspective: A Capability-Based Approach to EU-GDPR On the Difficulties of Incentivizing Online Privacy through Transparency: A Qualitative Survey of the German Health Insurance Market What is Your Selfie Worth? A Field Study on Individuals’ Valuation of Personal Data Justification of Mass Surveillance: A Quantitative Study An Exploratory Study of Risk Perception for Data Disclosure to a Network of Firms Track 12: Umweltinformatik und nachhaltiges Wirtschaften Kommunikationsfäden im Nadelöhr – Fachliche Prozessmodellierung der Nachhaltigkeitskommunikation am Kapitalmarkt Potentiale und Herausforderungen der Materialflusskostenrechnung Computing Incentives for User-Based Relocation in Carsharing Sustainability’s Coming Home: Preliminary Design Principles for the Sustainable Smart District Substitution of hazardous chemical substances using Deep Learning and t-SNE A Hierarchy of DSMLs in Support of Product Life-Cycle Assessment A Survey of Smart Energy Services for Private Households Door-to-Door Mobility Integrators as Keystone Organizations of Smart Ecosystems: Resources and Value Co-Creation – A Literature Review Ein Entscheidungsunterstützungssystem zur ökonomischen Bewertung von Mieterstrom auf Basis der Clusteranalyse Discovering Blockchain for Sustainable Product-Service Systems to enhance the Circular Economy Digitale Rückverfolgbarkeit von Lebensmitteln: Eine verbraucherinformatische Studie Umweltbewusstsein durch audiovisuelles Content Marketing? Eine experimentelle Untersuchung zur Konsumentenbewertung nachhaltiger Smartphones Towards Predictive Energy Management in Information Systems: A Research Proposal A Web Browser-Based Application for Processing and Analyzing Material Flow Models using the MFCA Methodology Track 13: Digital Work - Social, mobile, smart On Conversational Agents in Information Systems Research: Analyzing the Past to Guide Future Work The Potential of Augmented Reality for Improving Occupational First Aid Prevent a Vicious Circle! The Role of Organizational IT-Capability in Attracting IT-affine Applicants Good, Bad, or Both? Conceptualization and Measurement of Ambivalent User Attitudes Towards AI A Case Study on Cross-Hierarchical Communication in Digital Work Environments ‘Show Me Your People Skills’ - Employing CEO Branding for Corporate Reputation Management in Social Media A Multiorganisational Study of the Drivers and Barriers of Enterprise Collaboration Systems-Enabled Change The More the Merrier? The Effect of Size of Core Team Subgroups on Success of Open Source Projects The Impact of Anthropomorphic and Functional Chatbot Design Features in Enterprise Collaboration Systems on User Acceptance Digital Feedback for Digital Work? Affordances and Constraints of a Feedback App at InsurCorp The Effect of Marker-less Augmented Reality on Task and Learning Performance Antecedents for Cyberloafing – A Literature Review Internal Crowd Work as a Source of Empowerment - An Empirical Analysis of the Perception of Employees in a Crowdtesting Project Track 14: Geschäftsmodelle und digitales Unternehmertum Dividing the ICO Jungle: Extracting and Evaluating Design Archetypes Capturing Value from Data: Exploring Factors Influencing Revenue Model Design for Data-Driven Services Understanding the Role of Data for Innovating Business Models: A System Dynamics Perspective Business Model Innovation and Stakeholder: Exploring Mechanisms and Outcomes of Value Creation and Destruction Business Models for Internet of Things Platforms: Empirical Development of a Taxonomy and Archetypes Revitalizing established Industrial Companies: State of the Art and Success Principles of Digital Corporate Incubators When 1+1 is Greater than 2: Concurrence of Additional Digital and Established Business Models within Companies Special Track 1: Student Track Investigating Personalized Price Discrimination of Textile-, Electronics- and General Stores in German Online Retail From Facets to a Universal Definition – An Analysis of IoT Usage in Retail Is the Technostress Creators Inventory Still an Up-To-Date Measurement Instrument? Results of a Large-Scale Interview Study Application of Media Synchronicity Theory to Creative Tasks in Virtual Teams Using the Example of Design Thinking TrustyTweet: An Indicator-based Browser-Plugin to Assist Users in Dealing with Fake News on Twitter Application of Process Mining Techniques to Support Maintenance-Related Objectives How Voice Can Change Customer Satisfaction: A Comparative Analysis between E-Commerce and Voice Commerce Business Process Compliance and Blockchain: How Does the Ethereum Blockchain Address Challenges of Business Process Compliance? Improving Business Model Configuration through a Question-based Approach The Influence of Situational Factors and Gamification on Intrinsic Motivation and Learning Evaluation von ITSM-Tools für Integration und Management von Cloud-Diensten am Beispiel von ServiceNow How Software Promotes the Integration of Sustainability in Business Process Management Criteria Catalog for Industrial IoT Platforms from the Perspective of the Machine Tool Industry Special Track 3: Demos & Prototyping Privacy-friendly User Location Tracking with Smart Devices: The BeaT Prototype Application-oriented robotics in nursing homes Augmented Reality for Set-up Processe Mixed Reality for supporting Remote-Meetings Gamification zur Motivationssteigerung von Werkern bei der Betriebsdatenerfassung Automatically Extracting and Analyzing Customer Needs from Twitter: A “Needmining” Prototype GaNEsHA: Opportunities for Sustainable Transportation in Smart Cities TUCANA: A platform for using local processing power of edge devices for building data-driven services Demonstrator zur Beschreibung und Visualisierung einer kritischen Infrastruktur Entwicklung einer alltagsnahen persuasiven App zur Bewegungsmotivation für ältere Nutzerinnen und Nutzer A browser-based modeling tool for studying the learning of conceptual modeling based on a multi-modal data collection approach Exergames & Dementia: An interactive System for People with Dementia and their Care-Network Workshops Workshop Ethics and Morality in Business Informatics (Workshop Ethik und Moral in der Wirtschaftsinformatik – EMoWI’19) Model-Based Compliance in Information Systems - Foundations, Case Description and Data Set of the MobIS-Challenge for Students and Doctoral Candidates Report of the Workshop on Concepts and Methods of Identifying Digital Potentials in Information Management Control of Systemic Risks in Global Networks - A Grand Challenge to Information Systems Research Die Mitarbeiter von morgen - Kompetenzen künftiger Mitarbeiter im Bereich Business Analytics Digitaler Konsum: Herausforderungen und Chancen der Verbraucherinformati

Syntheses and electrochemical studies of bis(η5-cyclopentadienyl)-(2,3-quinoxalinedithiolato)titanium(IV) derivatives. Comparison with the electrochemical properties of similar complexes.

Neste trabalho descreve-se a síntese de novos derivados bis(η5-ciclopentadienil)(2,3-quinoxalina-ditiolato)titanio(IV) e bis(η5-ciclopentadienil)(1-fenil)(2-metil)(1,2-etenoditiolato)titanio(IV). As propriedades redox destes compostos juntamente com as propriedades de bis(η5-ciclopentadienil)(ene-1,2-ditiolato)titanio(IV) similares foram medidas em soluções neutras. Todos os compostos exibiram uma redução reversível envolvendo um elétron, sendo que o potencial de redução é dependente da natureza do ligante ditiolato. Um segundo processo de redução é observado para os derivados de 2,3-quinoxalina. As propriedades destes últimos também foram estudadas em meio ácido e a presença de H+ tem um pequeno efeito em ambos os processos, sugerindo que o mesmo tipo de evento ocorre sob as duas condições.In this work the syntheses of novel bis(η5-cyclopentadienyl)(2,3-quinoxaline-dithiolato)titanium(IV) derivatives and bis(η5-cyclopentadienyl)(1-phenyl)(2-methyl)(1,2-ethenedithiolato)titanium(IV) is described. The redox properties of these compounds along with the properties of similar bis(η5-cyclopentadienyl)(ene-1,2-dithiolato)titanium(IV) complexes are assessed in neutral solutions. All the compounds exhibited a reversible one electron reduction process, the potential at which the reduction occurs being dependent on the nature of the dithiolato ligand. A second reduction process is observed on the 2,3-quinoxaline derivatives. The properties of the latter are also assessed in acidic solution and the presence of H+ has a small effect on both processes, suggesting that the same type of event occurs under both conditions

Evaluation of risk to human health by natural arsenic contamination in groundwater and soils from the urban area of Ouro Preto (MG).

Na avaliação da exposição humana à contaminação natural por arsênio (As) das águas subterrâneas e solos na área urbana da cidade de Ouro Preto, MG), nos bairros Piedade, Taquaral, Padre Faria, Alto da Cruz, Antônio Dias e Barra, foram estimados, para as crianças e adultos residentes nesses locais: (i) os valores das doses de ingestão diárias (DID) de As; (ii) os valores para os quocientes de risco (QRs) e (iii) o incremento da probabilidade de se desenvolver câncer ao longo da vida (RC), com teores médios de As encontrados nas águas subterrâneas, variando entre 10 e 77 μg.L-1 e, nos solos, de 332,75 e 656 mg.kg-1.This study was performed so as to make an assessment of human exposure to natural contamination by arsenic (As) in groundwaters and soils in the urban area of Ouro Preto, MG), Brazil, specifically in the Piedade, Taquaral, Padre Faria, Alto da Cruz, Antônio Dias, and Barra neighborhoods. In this study, the following items were estimated for the children and adult residents in these locations: (i) the values of daily ingested doses (DID) of As; (ii) the values for risk quotients (QRs) and (iii) the increase of the probability of developing cancer throughout life (RC), with mean content of As found in groundwaters varying from 10 to 77 μg.L-1 and, in the soils, from 332.75 to 656 mg.kg-1

Coagulation-floculation des eaux issues des mines de fer : comparaison entre les coagulants minéraux et un coagulant organique issu de la moringa oléifera

Dans la région nomée Quadrilátero Ferrífero, à l état de Minas Gerais, Brazil, sont localisées quelques des plus importants dépôts minéraux de fer du monde. Dans cette même région on trouve le Bassin Hydrographique du Rio Doce et le sub-Bassin du Rio Piracicaba (Rivière Piracicaba), an affluent du Rio Doce. La région entourant le haut et le moyen cours du rivière présente plusieurs entreprises d exploitation du fer. Les activités minéraux sont fréquemment résponsables pour l augmentation des taux de lixiviation chimique et érosion des sols. Au début on a étudié les tenneurs des minéraux de fer dans des sédiments déposés sur le lit la rivière Piracicaba pour chercher l éxistence d une corrélation entre l ensablemment de la rivière et les activités mineures dans la région. Les échantillons prèlévées dans des sites à la voisinage des sources du Piracicaba ont présentées les tenneurs des minéraux de fer hématite et magnétite les plus importants. Les valeurs élevés des concentrations des oxydes de fer sont originés, probablément, du transport des sédiments des terrains des mines par des pétits affluents de la rivière. Les concentrations d hématite sur ces sites sont quatre fois plus importantes que les valeurs moyennes observées au long de la plage du Piracicaba recherchée. Donc, l étude des conditions pour accélérer la sédimentation des eaux superficielles troubles des mines de fer, avant qu elles ne se déversent dans la fleuve Piracicaba, sont prioritaires pour ceux concernés avec l équilibre hydrologique et environnemental de la région. Au courant de ce travail on a étudié la coagulation/flocculation des suspensions riches en particules des oxydes de fer en utilisant deux agents coagulants: le sulfate d aluminium (alumen) et un biopolymère naturel appellée Moringa oleífera. Les suspensions naturels sont composées essentiellement des minéraux goethite, hematite, kaolinite et quartz, qui présentent une charge superficielle nette positive sous les pH s de ce travail. Le sulfate d aluminium a présenté une bonne performance coagulante vers les suspensions riches en oxydes de fer. Le mécanisme de coagulation/floculation responsable pour la réduction de la turbidité des suspensions traitées a été investigué. Une première étape d adsorption spécifique des produits de l hydrolyse des sels d aluminium sur la surface des oxydes, suivie par un processus d hétérocoagulation entre les agrégats positivemente chargés et des particules chargées negativement présentes dans la suspension, a été proposé. Pourtant, depuis les années 1970, la toxicité de l aluminium est considerée menaçante pour la santé publique. En ce qui concerne l être humain le métal est suspecté d intervenir dans des maladies telles que le cancer et les maladies d Alzheimer et Parkinson. Moringa oleífera est un coagulant naturel extrait des graines d une arbre très bien adaptée au climat du Nord Brésilien dont les fruits sont largement employés dans l Afrique pour clarifier des eaux troubles sans présenter des risques environnementales. Des travaux en utilisant la Moringa comme coagulant pour les eaux riches en oxydes de fer n ont pas encore étés publiés. La performance de cet agent coagulant vers les suspensions naturelles provénantes des mines de fer est comparable à celle du sulfate d aluminium. Le mécanisme de coagulation/floculation des graines a été étudié par bilan de matière et des analyses du précipité par isotermes d adsorption, spectroscopie IR, diffraction des Rayons-X, spéctroscopie Mössbauer, analyse thérmique, des mésures de potentiel Zéta et par granulométrie laser pour suivre la taille des agrégats formés. La fraction coagulante active des graines de la Moringa oleífera est constituée par des proteínes cathioniques qui adsorbent sur les particules d oxydes. Le mécanisme de réaction proposé comprend deux étapes : à la première, il y a un encombrément de l oxyde par une monocouche de polymère, à la seconde étape, probablement, on a la formation des multicouches. La couche plus externe expose les sites cathioniques vers la solution, ce qui provoque la redispersion des particules pour des concentrations plus importants du coagulant.AIX-MARSEILLE3-BU Sc.St Jérô (130552102) / SudocSudocFranceF

Assinatura geol?gica e influ?ncia do uso e da ocupa??o do solo na geoqu?mica de ?guas e sedimentos da bacia do ribeir?o Cara?a, Catas Altas, MG.

O presente trabalho foi realizado na bacia hidrogr?fica do ribeir?o Cara?a, no munic?pio de Catas Altas, Minas Gerais. O objetivo principal foi obter par?metros qu?micos e f?sico?qu?micos para caracterizar a geoqu?mica das ?guas e sedimentos desta bacia e determinar a real influ?ncia das atividades antropog?nicas presentes na ?rea. As nascentes do ribeir?o Cara?a se encontram em uma ?rea de preserva??o ambiental (Parque Natural do Cara?a), isenta de contamina??o antr?pica; por?m, ao longo da bacia, existem diversos problemas de ordem ambiental, que podem ter origem na presen?a de ?reas urbanas, atividades de minera??o e agr?colas. Para este trabalho, foi realizado um estudo do uso e da ocupa??o do solo e monitorados 24 pontos, onde foram realizadas an?lises sazonais de ?gua (pH, Eh, condutividade el?trica e oxig?nio dissolvido) e medidos os teores de SO42 -, Cl- e HCO3 - (alcalinidade), al?m de metais (Al, Fe, Mn, Mg, Ca, K, Ti, P, As, Ba, Co, Cr, Cu, Ni, Sr, V, Zn e Zr, Na, K, Ca e Mg). Esses mesmos elementos foram determinados nas amostras de sedimentos. Os resultados permitiram dividir a bacia em tr?s ?reas distintas, com diferente ocupa??o e geoqu?mica. Apesar das atividades antropog?nicas mostrarem grande influ?ncia sobre a geoqu?mica das ?guas, a composi??o dos sedimentos ? influenciada fundamentalmente pela geologia local.The present study was carried out in the Cara?a stream basin, located at Catas Altas, Minas Gerais. The main goal was to obtain chemical and physical-chemical parameters in order to characterize the water and sediment geochemistry and ultimately to assess the real influence of the anthropogenic activities in the area. The springs are located in an environmental protection area (Parque Natural do Cara?a), which is free from anthropogenic influence. However, in the basin area there are several environmental problems which may be caused by urban areas, mining activities and farms. For this study, a land use and occupation assesment was carried out and 24 sampling stations were monitored, where seasonal water analyzes were carried out for pH, Eh, electrical conductivity and dissolved oxygen, concentrations of SO42 -, Cl- and HCO3 -(alkalinity) in addition to metals (Al, Fe, Mn, Mg, Ca, K, Ti, P, As, Ba, Co, Cr, Cu, Ni, Sr, V, Zn e Zr, Na, K, Ca and Mg). These same elements were also determined in sediment samples together with Si. The results allowed the division of the basin in three distinct areas according to occupation and geochemistry. The results show that the activities present in the basin have influence in that water quality, but the sediment composition is the reflex of only the local geology