CASCADA - Toxin or Treat?

The most sensitive glaciers to climate warming in the 21st century are situated in tropical mountain regions, and thus, serve as valuable sentinels of climate change. Most attention to date has focused on the quantity of meltwater released from these glaciers, because of the impact on global sea level and water security. The concurrent changes in water quality are much more poorly constrained, but have implications for drinking water, agriculture and industry. Peru holds 71% of all tropical glaciers, all of which have undergone high rates of mass loss and retreat in the last two decades. However, certain rivers fed by glacial meltwater are becoming acidic, with concentrations of metals often above World Health Organisation standards. This is thought due to the exposure of metal-rich (sulphidic) rocks in retreating glacier forefields, which release sulphuric acid and metals once oxidised - this acidity can no longer be neutralized by the intense chemical weathering which takes place beneath glaciers.

The overarching hypothesis that CASCADA will test is that glaciated catchments in the Cordillera Blanca are evolving along a trajectory from pristine conditions, where glacial runoff is an important nutrient source for downstream ecosystems ("treat"), to those in which the same runoff is toxic to ecosystems and human health ("toxin"). CASCADA unites Peruvian experts in water resources, glaciology and ecology with UK geochemists, glaciologists and technologists to investigate and generate solutions to the cascading impacts of glacier retreat on water quality in Cordillera Blanca rivers. It employs cutting edge in situ monitoring technologies to capture first time data on the year-round quality of Cordillera Blanca rivers and to develop and test a novel wetland management model to remediate rivers with high metal toxicity. A strong partnership with local water users' committees under a citizen science scheme and the formation of an engagement board with governmental institutions and local communities will ensure capacity building and the transfer of technology for integrated wetland management and water quality reporting. Thus, CASCADA provides the transformative process understanding required to deliver a step jump in our ability to predict water quality evolution in deglaciating terrains and to develop effective solutions to toxic catchments.

Who might benefit from this research?

We anticipate that the outcomes of this research will be of major importance internationally and that, ultimately, a wide range of interest groups would benefit. We have identified three main groups of people who would benefit from this research:

- Policy makers and government bodies managing water resources in Peru and mountain regions more generally: Regional/national policy and decision makers in Peru are in urgent need of concrete information about the status and value of water-regulating ecosystems in the high Andes. This is particularly true of rising water quality issues due to metal toxification. In the study catchments for CASCADA, local communities were able to fish 20 years ago but the same lakes are now acidic and have metal concentrations above World Health Organisation standards. Policy makers need to know 1) which other catchments are vulnerable? and 2) how to remediate the problem?

- Rural communities and local stakeholders. Local communities and their governing structures have a vested interest in remediating river waters (metal removal) because of the high impact of metal toxification upon ecosystems and their services. The novel citizen-science based wetland management tool developed by CASADA will be of direct benefit to these users.

- General public and wider interest groups. This is a topical subject of great interest to the general public; hence our research will be of widespread appeal. Peruvian glaciers in advanced retreat represent the "End Game" for other world mountain glaciers in a warming climate. Metal toxification of CASCADA field sites is highly visual, with orange rust (via iron oxidation) staining the landscape. This presents an opportunity to capture images of high visual appeal suitable for public engagement.

How might they benefit from this research?

- Engagement with policy makers: We will form an external engagement board at the start of the project, comprising key water resource managers at a regional and national level and community stakeholders. This group will meet annually and work with the PIs to maximise the policy relevant outputs from CASCADA in relation to water quality, and to ensure that CASCADA has a legacy beyond its time frame (e.g. generation of simple metrics predicting vulnerability, tools and data products).

- Rural communities and local stakeholders: CASCADA will directly collaborate with local communities and stakeholders using a citizen science based approach, developing a novel wetland management model which can be deployed by local communities (via the mobile app "AquaBioSmart", developed by Loayza-Muro).

- General public and wider interest groups: We will maintain an active presence at key public science engagement events/festivals, e.g. Bristol Festival of Nature (films), Science Alive and Schools visits. We will also capitalise on the highly visual evidence for glacier retreat and its water quality impacts in the Cordillera Blanca via a collaboration with Chouette Films. We will create the first immersive Virtual Reality (3D) film of deglaciation of tropical glaciers, transporting the viewer to the dramatic imagery of this changing landscape. We will collaborate with Chouette to produce 1) a high quality short (3 min) 3D film highlighting water quality impacts of melting tropical glaciers targeted at international film festivals and regional science Festivals such and 2) a web-based exploratory tour of our pristine and toxic study catchments aimed at educators, the general public and school children.