Peruvian Study Opens Doors for Glacial Research

A study published in March of this year by researchers from the University of Quebec presents a new avenue for glacier retreat research. While most water-related glacier studies are concerned with water availability, the research presented in this article is distinctive in that it draws a link between glacier retreat and water quality. This work has important implications for populations in the study area and others living in glacierized regions around the world.

Dissolved pyrite causes red deposit on rocks along a river in the Rio Santa watershed (Source: Alexandre Guittard)

This Peruvian study was conducted in the Rio Santa watershed in Peru, a freshwater source for 1.6 million people in a country currently suffering from water scarcity issues. For communities living within the Rio Santa watershed, its water resources are essential for drinking water, hydroelectricity, irrigation and recreation. However, freshwater in parts of the Rio Santa watershed have been found to be contaminated with trace metals. Water samples collected during this study showed concentrations of arsenic and manganese in the Rio Santa River are greater than the US Environmental Protection Agency drinking water guidelines, signaling potential hazards for water users. In certain doses, arsenic can be toxic and long-term exposure can lead to skin lesions, cancer, and infant mortality.

Researchers measured the debit of the Rio Santa using an ADCP (Source: Alexandre Guittard)

GlacierHub caught up with Michel Baraer, professor at the University of Quebec and co-author of this study. Baraer said their results yielded 2 major surprises. First, the main sources of trace metal contamination in the Rio Santa watershed are from both active and abandoned mines. Precipitation runoff washes traces of metals such as aluminum, arsenic, and zinc from the mines into nearby waterways. Second, the researchers did not see major differences in concentrations of metals with changes in discharge. In other words, there did not seem to be a connection between the amount of water flowing and metal contamination. This finding was unexpected because of the drastic difference between dry and wet seasons in the Rio Santa watershed. Over 80 percent of the yearly precipitation falls between October and April, leaving the summer months severely dry. River flow is determined by precipitation, snow and ice melt, groundwater, etc., elements that vary seasonally.  These results led Baraer and his colleague to conclude that the processes controlling metal concentrations in the Rio Santa watershed were more complex than simple dilution.

Researchers hiking to study the Quilcayanca glacier and its impacts on the hydrology of the valley (Source: Alexandre Guittard)

Baraer says their research found that glacier retreat has an indirect effect on water contamination in the Rio Santa watershed, as it affects different parts of the watershed over time. The researchers found that metal contamination decreased steadily downstream, meaning contaminants have mostly remained upstream and closer to their source. As a result, communities downstream have had a consistent freshwater supply. However, retreating glaciers change the flow pattern of rivers and tributaries, altering the quantity of water flowing downstream. As glaciers first begin to retreat, they increasingly release more water until they reach “peak water,” or the maximum output. The Rio Santa has passed this period of peak water, meaning stream flow is declining.  However, the decline in stream flow will mostly occur during the dry season. The wet season is expected to experience an increase in stream flow, as warmer temperatures cause more precipitation to occur as rain, rather than snow. This increase in discharge during the wet season has the potential to transport contaminants further downstream and closer to more populated areas that have historically had cleaner water. Baraer believes this to be the main takeaway from the article– that glacier retreat does have this indirect effect, and it is a useful case study for researchers in the area and other glaciated regions.

The Pastaruri glacier in the Rio Santa watershed has lost 20% of its size in 30 years (Source: Alexandre Guittard)

Baraer stressed the importance of educating the public about water contamination issues. Although he believes there are engineering projects that could address the contamination, they would be expensive and require substantial funding. Instead, Baraer said, “awareness should be the first priority.” Educating the public about trace metal contamination and the effects it may have on children and pregnant women is critical.

Along the Rio Santa in the city of Huaraz during the dry season (Source: Alexandre Guittard)

Research connecting glacier retreat to water quality is scarce and the impacts of glacier retreat on water quality remain largely unknown. Baraer says this article is just a starting point. Studies like this one are extremely important for communities dependent on these water sources. While discussing water scarcity issues in Peru, Baraer mused, “what if not only we get less water, but what if this water is not as good?” In addition to linking glacier retreat to water quality, the study begins to question who will be most affected, where and at what time. As for continuing this line of research, he has an article under review regarding organic water contamination. Baraer is also a member of the Transdisciplinary Andean Research Network, which conducts research at the intersections of climate change, glacier retreat, hydrological resources, water use, and societal adaptation.

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