Jon Molinero

Emerging contaminants, particularly pharmaceuticals, enter surface waters through untreated or partially treated wastewater and pose significant risks to human health and the environment due to their persistence in aquatic systems. This study evaluated the presence of diclofenac, acetaminophen, trimethoprim, sulfamethoxazole, and caffeine in surface and drinking water of Esmeraldas, Ecuador. Compounds were extracted using solid-phase extraction and detected by liquid chromatography and mass spectrometry. Caffeine was the most prevalent, detected in 66% of the samples, with significantly higher concentrations in surface waters than in domestic or commercial bottled water. It was also the only pharmaceutical detected in both domestic and commercial bottled water. Diclofenac and acetaminophen were detected less frequently (5% and 13% of samples, respectively), while trimethoprim and sulfamethoxazole were not detected. The maximum observed concentrations were 795 ng L^-1 of caffeine, 895 ng L^-1 of acetaminophen and 37.7 ng L^-1 of diclofenac. This study highlights the importance of monitoring of PHs in surface and drinking waters to safeguard both public health and the environment.

Illegal gold mining is on the rise in the tropical Andes. The Santiago-Cayapas watershed is located in the north of the Pacific basin of Ecuador, in the Chocó biogeographical region. It is recognized for its high biodiversity, as 62 fish species have been described in the area, and because it contains two of the largest protected areas in the Pacific coast of Ecuador: the mangroves of the Cayapas and Mataje Rivers and the Cotacachi-Cayapas Ecological Reserve. Open-pit gold mining has been described in the area since 2006 and most mining fronts operate illegally and lack any environmental control. Heavy-metal concentrations and fish communities were studied in streams that drain active and abandoned mines, in larger rivers located downstream of the mined areas and in control sites without mining activities. Open-pit mining causes a reduction of dissolved oxygen concentrations and an increase of water temperature, turbidity, and concentrations of Al, Cr, Co, Cu, Fe, Mn, and V. Fish abundance decreased in streams that drain active mines, however, metrics of taxonomic diversity remain unchanged among the study sites. The response of fish communities to open-pit gold mining was complex and driven by the pollution tolerance of each species, the presence of specific adaptions to turbid waters, and changes in the fishing pressure as locals avoid fishing activities in mined areas. Finally, streams that drain abandoned mines showed chemical characteristics, metal concentrations, and fish communities that were similar to control sites, but maintained higher water temperatures than control sites.

Universal access to safe water is a major global goal, but these efforts could be at stake because drinking water sources are becoming polluted in many developing countries. Chlorine, major ions, and heavy metals were measured in rivers and drinking water of Esmeraldas because potential pollution sources raise concerns about the quality of the water supply, and because users have developed strategies to cope with water shortages including collecting river water and water distributed by tankers, storing water at home, and consuming commercial bottled water. We sampled water from the water distribution system (WDS) and the Esmeraldas and Teaone rivers including the intake to the potabilization plant, water distributed by tankers, and commercial bottled water. Most of the samples collected from the Esmeraldas and Teaone rivers, the WDS, and tankers complied with drinking water standards, but higher concentration of cadmium and other metals in the eastern part of the city is an indication of corrosion inside the WDS. Commercial bottled and WDS water showed similar heavy metal concentrations, but regular consumption of some brands may lead to higher exposure to arsenic and mineral deficiencies. Chlorine concentrations in the water supplied by the WDS were below the values required for safe disinfection, and in-house chlorination is uncommon in the city. Strengthening pollution control in the Esmeraldas river, monitoring corrosion of the WDS, and promoting point-use chlorination and better water handling practices are required to secure a safer water supply in the long term.