Pressões minerárias na Bacia do Cassiporé e vulnerabilidades da Zona Costeira do Amapá: uma análise utilizando geotecnologias

Abstract

The formation of the state of Amapá is historically linked to mining, from eighteenth century gold prospecting to industrial operations initiated in the 1950s with ICOMI S/A. This study evaluated the environmental impacts of mining activities in the Cassiporé River Basin, focusing on the Cassiporé and Reginá rivers and their connection to the northern coastal zone of Amapá. The research was conducted in three stages: (i) a literature review and compilation of secondary data on legal and illegal mining operations, including ore type, geological context and documented environmental impacts; (ii) a temporal analysis from 1985 to 2024 using Landsat imagery and MapBiomas data to identify land-use and land-cover changes, particularly vegetation removal and its effects on soil, drainage and aquatic biota; and (iii) geotechnical mapping in a GIS environment (QGIS 3.32) to delineate mining areas, quantify deforestation and identify hydrosedimentary influence zones based on altimetry and digital terrain models. The results show a marked increase in mining-related deforestation, rising from approximately 1,000 ha in 1985 to nearly 4,000 ha in 2024, concentrated in the upper basin around the Lourenço district. This expansion occurs over mineral-rich lithologies of the Guiana Shield, intensifying both industrial and artisanal mining, often lacking adequate waste-containment structures. The combination of elevated headwaters and dense drainage networks suggests high potential for sediment and heavy-metal transport (including mercury, lead and cadmium) toward downstream areas, mangroves and the coastal zone, affecting water quality, ichthyofauna and food security in riverine communities. Overall, mining in the Cassiporé Basin presents significant physical and biological impacts and poses cumulative risks to Amapá’s coastal ecosystems, underscoring the need for continuous monitoring and more effective regulatory measures.