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.
A catalytic membrane reactor (CMR) was prepared using a commercial ceramic hollow fibre membrane of corundum and Pd‐loading was done using incipient wetness impregnation. This single Pd‐impregnated catalytic membrane reactor is able to impel different reactions by simply modifying the working parameters. Under very mild conditions, oxidation can be switched to hydrogenation reaction without losing the CMR activity. The catalytic tests were performed in semi‐batch mode at room temperature and 60ºC. The reactor was submerged into a vessel containing model solution of phenol or ibuprofen at concentrations in the range of 30–100 ppm. To one end of the membrane reactor hydrogen is supplied, whilst the other end was kept closed. Reactions were done suppling oxygen, air or no gas in the vessel. Depending on the availability of dissolved oxygen, the reactions followed different pathways leading to the hydrogenated or oxidized products. The oxidation pathway goes through the formation of H2O2 that further oxidize the organic matter, while when no oxygen is supply, the hydrogenation of the organic molecules takes place.
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