Ameaças e vulnerabilidade socioambiental associadas à poluição por metais pesados na bacia hidrográfica do Río Quito (Chocó-Colômbia): proposta de uma estrutura sistêmica para a gestão de riscos

Abstract

This research analyzed the factors of hazard and socio-environmental vulnerability associated with heavy metal contamination in the Quito River basin (Chocó, Colombia), recognized as a subject of rights under Constitutional Court Ruling T-622 of 2016. An etymological analysis was conducted, through which the convolution relationship between hazard and vulnerability was established as external and internal components of risk, respectively. Based on cartographic information, the expansion of mining activities in the Quito River basin was evaluated, and contamination levels in sediments were determined, showing concentrations of mercury (5,22 mg/kg), chromium (56,85 mg/kg), and arsenic (20,31 mg/kg) in areas heavily impacted by mining, along with turbidity levels exceeding 250 NTU. A significant morphological alteration of the fluvial system was evidenced, including the accumulation of sand banks with an estimated volume of over 43 million m3, and high population exposure to environmental and health-related risks. In parallel, a systematic literature review of 98 scientific articles was conducted, which enabled the identification of 66 tools (mostly indices) and 58 socio-environmental aspects considered in risk management studies. The analysis of this body of work revealed that the identified tools focus primarily on the quantification of heavy metal concentrations, without integrating relevant social, economic, ecological, and cultural dimensions for a comprehensive risk assessment. Accordingly, with the aim of proposing a systemic structure for the integrated management of socio-environmental risk resulting from heavy metal contamination in the Quito River basin, the 58 aspects were prioritized through expert consultation, and their influence–dependence relationships were analyzed using MICMAC software. This process led to the identification of 21 key variables within the system. Based on the etymological analysis of risk components, a systemic structure was developed in which variables such as water and soil contamination by heavy metals represent the magnitude of the hazard; the expansion of illegal mining is linked to its spatial extent; and climatic factors such as rainfall are associated with the temporal dimension. Regarding vulnerability, exposure is reflected in variables such as the ingestion of contaminated water and food, while sensitivity and adaptive capacity are linked to access to sanitation services and vegetation cover. The conceptual model provides a framework for guiding the formulation of integrated socio-environmental risk management instruments in river basins affected by illegal mining, such as the Quito River.