No abstract

The Iron Quadrangle has been the scenery of the most important gold production in Brazil. It is estimated that during the three centuries of gold mining in the Iron Quadrangle, at least 390,000 t of arsenic was discharged into the drainage system. This study presents geochemical data for the three river basins in the region, with focus on surface water and stream sediment monitoring. Samples of primary and oxidized sulfide ores as well as of tailings and groundwater from the major gold mines were also studied. The highest As concentrations in water and stream sediments occur in the vicinity of mining areas. In surface water, up to 300 lg As/l were found whereas the As contents in stream sediments were in the range of 20 to 4,000 mg/kg. The As 3+ /As 5+ concentration ratios obtained for some water samples range from 1.10 )1 to 4.10 )2 . The As mobility associated with ore-deposit weathering could be traced in some closed gold mines by observation of insitu pyrite and arsenopyrite oxida-tion, precipitation of scorodite and gippsite, As adsorption onto goethite, and final liberation of As into underground and surface waters. This process is likely to produce large volumes of mine effluents containing total As and trivalent As up to 1,960 and 60 lg/l, respectively. River sediments and tailings pile samples were submitted to a leaching procedure showing maximal arsenic release from 1 to 4% of the original total As in the samples. There are potential risks for As hazards in some areas induced by, for instance, the dispersion of old tailings by flooding, occupation of poisoned soils for settlements, and occasional consumption of contaminated surface and groundwater.

Since the end of 17th century, the Iron Quadrangle in the State of Minas Gerais has been known as one of the most famous gold producing regions in Brazil. Gold was initially produced from alluvial placers and oxidation zones and, finally from primary ores in modern times. Total gold production must have exceeded 13001 in all history. Only in the very famous Morro Velho mine around 600-t gold has been produced since 1834. The gold ore is rich in arsenic with the As/Au ratios ranging from 300 to 3000 among the several deposits deposits. The arsenic in rocks and ores (pyrite, pyrrhotite and arsenopyrite) undergo oxidation during the weathering processes and part of the arsenic is naturally liberated into the environment. Since the tailings produced in the past were discharged directly into drainage until 1980, the amount of arsenic that entered the drainage systems must have exceeded 3900001 in the whole region. In the Iron Quadrangle region, the highest arsenic concentrations in water and sediment occur near the mining areas where the river sediments were contaminated by tailing discharge since colonial times. In surface drainage water, the dissolved arsenic concentration ranges from <2 to > 160 mg/L, and from <20 to >2830 mg/kg in the stream sediments. Although the present mine operations do not contribute significantly to contamination of the rivers, there are a potential risk for arsenic hazard in some areas induced by, for instance, dispersion of old tailings by flooding, occupation of polluted soils and consumption of contaminated surface and underground water.

No Quadrilátero Ferrífero (QF), o abastecimento público de água é feito principalmente com a captação de águas das bacias hidrográficas. Entretanto, em alguns locais, há a utilização de água subterrânea, proveniente de nascentes ou mesmo de minas abandonadas, para o abastecimento humano. As principais fontes naturais de As no QF estão relacionadas às rochas que hospedam depósitos auríferos sulfetados. As fontes antrópicas de As são as pilhas de rejeito, solos e sedimentos contaminados. Em águas coletadas em algumas minas auríferas subterrâneas e nascentes das regiões de Ouro Preto e Mariana, foram encontradas concentrações de As total variando de 2 a 2980µg/L e de As3+ de 1 até 86 µg/L. Com base nos estudos geológicos e hidrogeoquímicos da ocorrência de As, nas rochas e nas águas subterrâneas, observou-se que as maiores concentrações de As são encontradas nos aqüíferos hospedados em rochas que possuem sulfetos e carbonatos, embora as concentrações dos aqüíferos que possuem somente sulfetos também foram elevadas. O monitoramento de As na água subterrânea deve ser periódico, independentemente de sua ausência num primeiro momento, nos poços e em outras fontes de captações de águas subterrâneas atualmente em utilização no abastecimento público ou privado.
In the Iron Quadrangle region the public supply of water is done mainly by the impound of water of watersheds. However, in some places, the population use spring water or ground water from closed mines for human consumption. The main natural sources of As in the Iron Quadrangle are related to the rocks that contain lode gold deposits. The antropic sources of As are contaminated refuse piles, soil, and sediment. It was found total As concentration varying from 2 to 2,980 µg/L and As3+ from 1 to 86 µg/L in water samples collected in underground gold mines, artesian wells, and springs in Ouro Preto and Mariana counties. Based on geological and hydrogeochemical studies of the occurrence of As in rocks and groundwater, it was found that the highest As concentrations occurred in aquifers hosted in carbonate sulphide rich rocks. The As monitoring in underground water should be done periodically, independent of its absence in a first instance, in wells and other groundwater caption sources that are used nowadays for public or private suppliers

Environmental exposure to arsenic (As) in terms of public health is receiving increasing attention worldwide following cases of mass contamination in different parts of the world. However, there is a scarcity of data available on As geochemistry in Brazilian territory, despite the known occurrence of As in some of the more severely polluted areas of Brazil. The purpose of this paper is to discuss existing data on As distribution in Brazil based on recent investigations in three contaminated areas as well as results from the literature. To date, integrated studies on environmental and anthropogenic sources of As contamination have been carried out only in three areas in Brazil: (1) the Southeastern region, known as the Iron Quadrangle, where As was released into the drainage systems, soils and atmosphere as a result of gold mining; (2) the Ribeira Valley, where As occurs in Pb-Zn mine wastes and naturally in As-rich rocks and soils; (3) the Amazon region, including the Santana area, where As is associated with manganese ores mined over the last 50 years. Toxicological studies revealed that the populations were not exposed to elevated levels of As, with the As concentrations in surface water in these areas rarely exceeding 10 microg/L. Deep weathering of bedrocks along with formation of Fe/Al-enriched soils and sediments function as a chemical barrier that prevents the release of As into the water. In addition, the tropical climate results in high rates of precipitation in the northern and southeastern regions and, hence, the As contents of drinking water is diluted. Severe cases of human As exposure related to non-point pollution sources have not been reported in Brazil. However, increasing awareness of the adverse health effects of As will eventually lead to a more complete picture of the distribution of As in Brazil.

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This study sought to examine the variations of internal and external load measures in soccer players when performing different types of 4 vs. 4 small-sided games (SSGs). Ten U-23 professional and sub-elite soccer players, eight outfield players (age: 20.1 ± 1.5 years old; height: 1.83 ± 0.04 m; total body mass: 76.1 ± 3.6 kg) and two goalkeepers (GK) (age: 20.5 ± 2.1 years old; height: 1.91 ± 0.04 m; total body mass: 77.0 ± 1.4 kg) participated in the study. Five SSGs were performed with 3 min duration and 3 min rest interval. SSG1, SSG2 and SSG4 aimed for ball possession play, while in SSG3 and SSG5, two GK were added, defending regular-size goals. The pitch size changed from SSG1 (16 × 24 m) to SSG2 and SSG3 (both 20 × 30 m) and SSG4 and SSG5 (both 24 × 36 m). All players were monitored using WIMU Pro device during the tasks. Anova One-Way and the post hoc Tukey honestly significant difference were used for analysis of statistically significant differences (p < 0.05) and effect sizes were determined by calculating partial eta-squared. The framework was associated with relevant but steady state internal load fatigue and induce a considerable external load stimulus. GK participation in SSGs should be carefully considered as it seems to have a greater impact on physical load measures when compared to the pitch size manipulation.

Advances in technologies to enable water reuse in industry have been the objective of many research efforts, mainly due to the need to reduce the use of natural resources and due to factors related to their availability. This paper evaluates the crystallization of salts from petrochemical saline waste to achieve zero water discharge by the recovery of water and dissolved salts as a solid mixture. In line with process symbiosis, the recovered water should be suitable for use as cooling water in heat exchangers. Vacuum evaporative crystallization, at the batch scale, was used to remove the salts present in the concentrated stream from reverse electrodialysis of pretreated wastewater by a biological process. The partition of organic compounds in the feed solution between the condensate and the mother liquor was obtained from measurements of the total organic carbon and total nitrogen in the solutions. The solid phases formed experimentally are compared with those predicted by chemical modelling by PHREEQC. The recovered water presented almost 50 times less total dissolved solids than the feed stream (from 2100 to 44 mg/L). Calcium sulphate hydrate, calcium sulphate and sodium chloride were the majority crystalline phases formed, in accordance with the modelling by PHREEQC.