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Resumo O Distrito Areeiro de Seropédica-Itaguaí, considerado um dos maiores do Brasil, fornece aproximadamente 70% da areia para a construção civil da Região Metropolitana do Rio de Janeiro. O processo de extração de areia se dá através da retirada das camadas sedimentares superfi ciais, caracterizadas predominantemente por depósitos de areia, fazendo com que a superfície freática do Aquífero Piranema afl ore, preenchendo as cavas resultantes. Os depósitos de areia originaram-se sob condições redutoras, associadas a ambiente deposicional de linhas de costa e mangues, o que proporcionou a formação de sulfetos. Com a exposição dos sedimentos com a lavra, ocorre oxidação dos sulfetos e aumento dos teores de SO 4 na água, que podem alcançar valores superiores a 90 mg.l -1 , o que intensifi ca a solubilização de minerais alumino-silicáticos e consequente aumento das concentrações de Al (> 10 mg.l -1 ) nas águas.Palavras-chave: hidrogeoquímica, acidifi cação, lagoas de cava, água subterrânea. Abstract Impact of sand mining upon the Groundwater Chemistry, Piranema Sand Mining District, Itaguaí and Seropédica region, Rio de Janeiro.The Seropédica-Itaguaí Sand Mining district supplies about 70% of sand for civil construction of Rio de Janeiro Metropolitan Region. The sand extraction process is fact by the remove of the surface sedimentary layers; make water table fi lls the produced hole. The sand extraction activities cause the oxidation of reduced sediments (ancient coast lines lithologies -mangrove environment), providing low pH values (reaching values < 4) and high SO 4 contents (reaching more than 90 mg L -1 ). The relatively high acidity of these waters, similar to ore pit lakes environment and associated acid mine drainage, contributes to accelerated weathering rate, especially the silicates minerals, which produces high concentrations of Al (> 10 mg.L -1 ).

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Economic growth promoted by large investment projects in the city of Seropédica and surrounding areas is not accompanied by a territorial planning that supports future growth scenarios. The challenge of the municipality is to prepare to have its territory fully transformed. This study aimed to establish quantitative data on the interferences that the growth model practiced has caused in its main watercourse called Valão dos Bois. For this, its morphometric characteristics and physicochemical parameters of water quality were measured, and computational simulations of the self-purification processes were performed at various points, as well as the infiltration and precipitation processes, surface flow and leaching in four occupation scenarios of the urbanized areas of the basin, for rains with five different return periods. Journal of Environmental Protection and treatment systems. It is common in the early stages of urban growth, when the city's population is still small, the use of pits and sinks. In later stages, municipal managers are unlikely to invest in sewage collection and treatment systems, forcing the population to discharge their sewage into the rainwater drainage network without any treatment [2]. Currently, in Brazilian cities, river waters, in general, are attributed negative aspects, almost always associated with pollution, diseases, odors, among others.Urban rivers are thought to be responsible for flooding, causing disruption to the population. The Brazilian urbanization model has contributed to this situation in several aspects. Tucci [3] highlights two main flood-generating processes, the first related to the increase of urbanization with unplanned municipal zoning, high soil sealing index and rectification of drainage channels. The constant reduction of soil infiltration makes existing drainage systems unfeasible and makes future networks more expensive according to Giudice and Mendes (2013). Tucci [2] shows that as the urbanization rate increases, the maximum flow increases up to 7 times. The current urbanization model also contributes to flooding by favoring widespread urbanization, pushing residents farther from the old central areas, mostly located near the rivers, impoverishing upstream regions, causing the flow of downstream water (in the central areas) is larger and more concentrated. The second flood-generating process is the natural phenomenon of occupation of the larger riverbeds due to extreme rainfall. It should be noted that floods are natural facts, being a stage present in the common hydrological cycle in regions with or without human occupation [4]. Added to this is the fact that the first process is related to the second, as the more the soil is waterproofed, the greater the volume of water towards the river, which shifts the flood line further, near the occupied areas. These processes occur in the territory because human occupations do not consider the limitations of the environment in which it operates. Disregarding the limitations of the surrounding environment and altering ...

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