An Integrative Approach to Assess the Environmental Impacts of Gold Mining Contamination in the Amazon

Abstract

As the number of legal and illegal gold mining sites increases in the Andes–Amazonia region, integrative methods to evaluate the effects of mining pollution on freshwater ecosystems are of paramount importance. Here, we sampled water and sediments in 11 sites potentially affected by gold mining activities in the Napo province (Ecuador). The environmental impacts were evaluated using the following lines of evidence (LOEs): water physicochemical parameters, metal exposure concentrations, macroinvertebrate community response (AAMBI), and toxicity by conducting bioassays with Lactuca sativa and Daphnia magna. Dissolved oxygen and total suspended solids were under (<80%) and above (>130 mg/Ls) quality standards 65% of the sites. Ag, Al, As, Cd, Cu, Fe, Mn, Pb, and Zn in water and V, B, and Cr in sediments were detected above quality standards at sampled sites. Nine out of eleven sites were classified as having bad environmental quality based on the AAMBI. L. sativa seed germination in both water (37% to 70%) and sediment (0% to 65%) indicate significant toxicity. In five sites, neonates of D. magna showed a 25% reduction in survival compared to the control. Our integrated LOEs index ranked sites regarding their environmental degradation. We recommend environmental impact monitoring of the mining expansion at the Andes–Amazonia region using multiple LOEs.

Human health risk assessment of metals and metalloids in mining areas of the Northeast Andean foothills of the Ecuadorian Amazon

“…Additionally, given the high contribution of As, Cd, Pb, and Cr to the HI and TCR, local people should be informed and protected from exposure to contaminated water and sediments. Therefore, we advocate the provision of alternative water sources, the incentivizing of information campaigns, the facilitation of medical care, and the monitoring of the food chain supply, because metals can be easily transferred to edible plant parts (Gerson et al, 2021; Romero‐Estévez et al, 2019), to invertebrates (Capparelli et al, 2021), and to fish (Benefice et al, 2010; Lima et al, 2022) along the food chain.…”

“…Data on metal and metalloids concentration in surface water and sediments were obtained from Capparelli et al (2021). The water samples were collected at the center of the stream at mid-depth (according to the possibilities of each stream), and superficial sediment samples were collected at the riverbank at a depth of 15 cm.…”

“…Samples were taken from 11 sites downstream from GM areas located within or right at the limits of the federal mining concessions. From the 44 compounds analyzed in Capparelli et al (2021), we selected 12 (Ag, Al, As, B, Ba, Cd, Cu, Fe, Mn, Pb, V, and Zn) because of their potential toxicity to human health. Nine of these compounds (Ag, Al, As, Cd, Cu, Fe, Mn, Pb, and Zn) exceeded national or international regulatory standards for water and two (B and V) for sediments (Tables 1 and 2).…”

“…This study was motivated by the high levels of metals and metalloids reported in the Napo province by Capparelli et al (2021) and the concern these authors raised for the health of local freshwater ecosystems and Indigenous populations. The study suggests chronic toxicological risks in all sites evaluated and potential carcinogenic risks in most of the sites.…”

“…As a consequence of GM, concentrations of metals and metalloids greater than established environmental thresholds have been detected in rivers of the southern provinces of Sucumbios and Orellana (Carrillo et al, 2021;Escobar-Segovia et al, 2021;Rivera-Parra et al, 2021). In the Napo province, studies carried out in areas affected by GM have also detected metals and metalloids in environmental concentrations exceeding quality standards for both water and sediment (Capparelli et al, 2020(Capparelli et al, , 2021Galarza et al, 2021). Based on the dataset of Capparelli et al (2020), the HHRA made by Jiménez-Oyola et al (2021) suggests that local populations in the Napo province are at risk through contact with multiple exposure routes (i.e., mining, urban pollution, fish farming, and lixiviate from dumping areas).…”