Recognition criteria, characteristics and implications of the fluvial to marine transition zone in ancient deltaic deposits (Lajas Formation, Argentina)

The seaward end of modern rivers is characterized by the interactions of marine and fluvial processes, a tract known as the fluvial to marine transition zone, which varies between systems due to the relative strength of these processes. To understand how fluvial and tidal process interactions and the fluvial to marine transition zone are preserved in the rock record, large-scale outcrops of deltaic deposits of the Middle Jurassic Lajas Formation (Neuquen Basin, Argentina) have been investigated. Fluvial–tidal indicators consist of cyclically distributed carbonaceous drapes in unidirectional, seaward-oriented cross-stratifications, which are interpreted as the result of tidal modulation of the fluvial current in the inner part of the fluvial to marine transition zone. Heterolithic deposits with decimetre-scale interbedding of coarser-grained and finer-grained facies with mixed fluvial and tidal affinities are interpreted to indicate fluvial discharge fluctuations (seasonality) and subordinate tidal influence. Many other potential tidal indicators are argued to be the result of fluvial–tidal interactions with overall fluvial dominance or of purely fluvial processes. No purely tidal or tide-dominated facies were recognized in the studied deposits. Moreover, fluvial–tidal features are found mainly in deposits interpreted as interflood (forming during low river stage) in distal (delta front) or off-axis (interdistributary) parts of the system. Along major channel axes, the interpreted fluvial to marine transition zone is mainly represented by the fluvial-dominated section, whereas little or no tide-dominated section is identified. The system is interpreted to have been hyposynchronous with a poorly developed turbidity maximum. These conditions and the architectural elements described, including major and minor distributary channels, terminal distributary channels, mouth bars and crevasse mouth bars, are consistent with an interpretation of a fluvial-dominated, tide-influenced delta system and with an estimated short backwater length and inferred microtidal conditions. The improved identification of process interactions, and their preservation in ancient fluvial to marine transition zones, is fundamental to refining interpretations of ancient deltaic successions.Centro de Investigaciones Geológica

High prevalence of HIV-associated neurocognitive disorders (HAND) in São Paulo City, Brazil

Introduction: HIV-associated neurocognitive disorders (HAND) are the subject of many studies, some of them reporting a prevalence of up to 50 percent. Objectives: To determine the prevalence and factors associated with HIV neurocognitive disorders (HAND) in a cohort of HIV-1-infected patients in São Paulo city, Brazil. Methodology: Descriptive cross-sectional study including 106 HIV-1-infected patients, employing direct interview and neuropsychological tests, applied by trained neuro-psychologists with expertise in the tests. Other, similar assessment tools we used were Brief Neurocognitive Questionnaire, International HIV Dementia Scale, Lawton Instrumental Activities of Daily Living, Hospital Anxiety and Depression Scale, Social Support Scale for People with HIV/Aids, Assessment of Adherence to Antiretroviral Therapy Questionnaire, and a complex neuropsychological assessment. Results: We included 106 patients from May 2015 to April 2018. We found a high prevalence of HAND in our patients (45%), with 27.5% presenting asymptomatic neurological impairment (ANI) and 17.5% mild neurological dysfunction (MND); only one patient presented HIV-associated dementia (HAD) (0.9%). Women were more likely to have MND (52.9%) and the only case of HAD was also female. The high prevalence of neurocognitive disorders was independent of the immunological status, use of efavirenz, or virological control. Conclusions: This study may mirror the national and international scenarios, showing a high prevalence of HAND (45%) and the prevalence of some risk factors, in special among women

Fighting HIV/AIDS in a developing country: lessons from a small cohort from the largest Brazilian city

Not Applicabl

A heuristic system for environmental risk assessment of mercury from gold mining operations

Mercury pollution in the Amazon region represents today one of the most serious environmental issues faced by mankind. Quantities from 70 to 170 tonnes of mercury are discharged into the Amazonian environment annually from gold mining operations conducted by so-called “garjmpeiros” or informal miners. The transformations of mercury in the environment are not well understood by non-technical people and neither are methods to alleviate dangerous situations. As the issue is fraught with complex and vague concepts, Expert Systems can play an important role in transferring heuristic knowledge to non-technical people interacting directly with miners. A synergy is obtained if these people are also made aware of the toxic effects of mercury, methods to minimize emissions and of methods to diagnose critical situations. This work shows how an Expert System, HgEx, was developed to assist non-expert people to obtain a preliminary Hg bioaccumulation risk assessment without conducting a complex monitoring program. Fuzzy Logic techniques and a new weighted inference method allow program users to input imprecise field observations and still obtain conclusions about pollution extent and bioaccumulation possibilities. Because of its simplicity and ability to combine complex technical issues together with heuristic operational observations, the technology of an Expert System can play an important role in providing a rapid risk assessment for non-technical people. An initial picture of the contamination potential of a region or mining site together with measures to minimize mercury emissions and remedy critical situations are the main results presented to users who might include health workers, environmental and mining inspectors, engineers, biologists, etc. This work also stresses the importance of organic-rich environments in Hg-complex formation and points out the importance of vegetation fires as an additional source of Hg not previously considered in the Amazon. The tutorial part of the system can give guidelines for mercury-monitoring field work as well as an overview on the mercury biogeochemical cycle.Applied Science, Faculty ofMining Engineering, Keevil Institute ofGraduat

ARTISANAL MINERS AND MERCURY USE IN LATIN AMERICA.....................................................................................................2 FACTS AND FANTASIES ABOUT MERCURY......................................................................

Eserde "Marmara Üniversitesi Fen-Edebiyat Fakültesi Kütüphanesi" Ve Matbaa (Darü't-Tıbaati'l-Âmire) Mühürleri Vardır

Implementing programs to improve gold recovery and reduce environmental impacts by artisanal gold mining in Brazil

Artisanal and small-scale gold mining (ASM) is the largest source of mercury release into the environment from intentional use sources. One of the largest sites is located in the Tapajos River Basin region, in the Brazilian Amazon. In 2002 GEF/UNDP/UNIDO (United Nations Industrial Development Organization) implemented the GMP (Global Mercury Project) in Brazil, aiming at the reduction of mercury emissions through the introduction of simple technologies, as well as the implementation of health and environmental awareness. The program trained 4,200 miners in 115 mining sites in Brazil. The main highlights are the improvement of gold concentration by the use of “zig-zag” sluice boxes with better carpets, demonstration of closed-circuit amalgamation conducted in excavated lined pools, introduction of an electrolytic mercury activation process, introduction home-made retorts, refilling of old pits with tailings as a step to reclaim degraded areas. The original survey has shown 64.6% of miners in selected areas refilling old pits, 58.3% retaining sediments, 12.5% recycling mercury, 35.4% conducting amalgamation in lined pools, 43.8% using latrines, 20.8% drinking filtered water and 43.8% collecting their garbage. These numbers escalated to 100.0, 91.7, 91.7, 75.0, 100.0, 81.3 and 100.0% respectively, 90 days after the GMP training program and awareness campaign.Applied Science, Faculty ofMining Engineering, Keevil Institute ofUnreviewedOthe

Planning for closure in the post-industrial age : a proposed framework for building more sustainable mining communities

The focus of mine closure policies and practice in British Columbia has undergone considerable change since the first closure laws were enacted in the late 1960s. Even though the technical standards for determining a successful mine reclamation project have risen considerably over the past three decades, the public's growing hostility toward the industry suggests that expectations have risen even faster. With terms such as "ecological footprint", "carrying capacity", and "sustainability" becoming part of the language of everyday discourse, the mining industry is under enormous pressure to demonstrate that mine closure and reclamation practices are consistent with the public's increasingly sophisticated understanding of what constitutes sustainable development. In response the mining industry has begun to integrate sustainability principles into their operational and closure planning, but developing a framework for measuring actual system performance remains elusive. Sustainable Development Indicators (SDIs) provide a tool for identifying and measuring progress toward sustainability but a problem with many of the commonly used indicators is that they were developed by experts for experts and as a result fail to resonate with the public. With a more pluralistic, inclusive selection process SDIs have the potential to significantly alter the public's perception that mining is antithetical to the concept of sustainability. The authors conclude by proposing a framework for creating indicators of reclaimed areas that utilizes a heuristic model to integrate technical and ecological data with local knowledge. This model would assist reclamation planners in determining which indicators are critical in shaping the opinions of the different stakeholder groups.Applied Science, Faculty ofMining Engineering, Keevil Institute ofUnreviewedOthe

Garimpo Canaan : a successful case of reclamation of an artisanal gold mine in the Amazon

Deforestation in the Brazilian Amazon region was increased in the 1970’s. The total amount of forest already cut to the date is over 700,000 km² or over 18% of the original forest. Mining activities in the Amazon also escalated after 1970, with thousands of artisanal miners extracting gold and removing portions of forest and soil along the riverbanks and streams, causing deforestation and releasing sediments and mercury into the water bodies. In the last three decades, hundreds of thousands of pits were opened in the process of colluvial gold exploitation and most of these pits have never been refilled. Following a common trend, miners migrate to new areas without reclaiming the mines spreading the environmental impact all over the Amazon. About 300 to 600 new open pits formed by hydraulic monitor mining are opened annually in the Tapajós region, the world’s largest artisanal gold mining area. In the Tapajos River basin, an example of good artisanal gold mining practice was identified. The owner of the “Garimpo” Canaan has introduced outstanding environmental practices which have made the area a reference in reclamation of open pits in the region. In this site, most old pits have been backfilled with the tailings from new excavations. In some refilled pits the vegetation is recomposing naturally and others have been reforested. After 6 years of plantation some areas showed trees with average diameter of 15 cm, height of 10 m and volume of 23 m3/ha. This example represents not only an environmental achievement but also a long-term alternative of economic diversification for miners in the area, as the surface gold deposits have been depleting in a fast pace.Applied Science, Faculty ofMining Engineering, Keevil Institute ofUnreviewedOthe

Knowledge sharing in artisanal mining communities : mercury, technology and sustainability in developing countries

As gold has risen in value and artisanal gold mining has increased in many low income countries, there has been an increasing need for sustainable development models that promote environmental protection while enhancing the contribution of this activity to poverty alleviation. Artisanal mining provides a critical source of income for an estimated 15 million poverty-driven miners around the world, mainly in Africa, Asia and Latin America. However, its environmental impacts are often extensive, with mercury pollution posing major threats to human health and diverse ecosystems. 1000 tonnes of mercury are polluted annually into the environment due to mercury misuse in artisanal gold mining. This paper reviews community development models pioneered by local community practitioners and international experts as part of an initiative by the United Nations Industrial Development Organization, which can help to overcome environmental, social and economic challenges. We discuss the introduction of various technical options, from simple innovations that allow mercury containment, recycling and re-use, and also emphasize the importance of technologies of grinding and crushing that can be developed from local materials to further enhance income potential. While various past development efforts have sought to reduce mercury-related problems, we conclude that sustainable development should seek to intertwine knowledge-sharing on environmental goals with concrete ways of improving economic well-being. We demonstrate how such models of knowledge-sharing can help to catalyze local innovation, technology-sharing and community organization. We also discuss how this knowledge can be applied by governments to create capacitybuilding policies as well as regulations that support sustained improvement in mining standards.Non UBCUnreviewedOthe

Gravity Concentration in Artisanal Gold Mining

Worldwide there are over 43 million artisanal miners in virtually all developing countries extracting at least 30 different minerals. Gold, due to its increasing value, is the main mineral extracted by at least half of these miners. The large majority use amalgamation either as the final process to extract gold from gravity concentrates or from the whole ore. This latter method has been causing large losses of mercury to the environment and the most relevant world’s mercury pollution. For years, international agencies and researchers have been promoting gravity concentration methods as a way to eventually avoid the use of mercury or to reduce the mass of material to be amalgamated. This article reviews typical gravity concentration methods used by artisanal miners in developing countries, based on numerous field trips of the authors to more than 35 countries where artisanal gold mining is common.Applied Science, Faculty ofMining Engineering, Keevil Institute ofReviewedFacult