Environmental impacts of sand mining in the city of Santarem, Amazon region, Northern Brazil

The urban growth in the Amazon countryside region was led by great infrastructure projects, which demanded a major amount of raw material for civil construction such as sand. The sand mining in the Santarem city, Para state, is being developed over siliciclastic rocks from the Alter do Chao Formation. This exploitation lacks technical knowledge and standards, leading to low regard for the environment. The main purposes of this paper are to map the sand exploitation areas in Santarem and to understand their impacts on nearby communities throughout the whole life cycle of the mine. For that a case study was performed in Serra do Indio, where sand mining was an important activity for many years. The volume of withdrawn sand was determined, the environmental impacts were identified and classified, and measures to mitigate the main impacts were proposed. Overall, 21 sand-mining areas were identified in Santarem. Seven of them are legally active, three are irregularly exploited, and eleven are inactive. All of them use mechanical dismantle for the extraction process. This method generates soil compaction and emits air and sound pollution on site and to nearby areas. In Serra do Indio, between 2002 and 2014, around 14,059 m(3) of sand were extracted. As a consequence, laminar flows and ravines, which facilitate gravitational mass movements, caused siltation of nearby rivers. The lack of technical criteria has decreased the mines' lifetime and increased the environmental harm related to the sand exploitation, in Santarem, Amazon countryside region.