Satellites monitor algae toxin levels to ensure drinking water safety

Imagine that your daily routine is disrupted by a sudden ‘do not drink’ advisory for your local tap water because of elevated toxin levels. This scenario became a reality for cities like Toledo, OH in 2014, affecting more than 400,000 residents.

The source? Microcystins — toxins produced by cyanobacteria, commonly referred to as blue-green algae. As climate change and human activities lead to increased eutrophication and dangerous blooms in more lakes, the threat to our drinking water safety has intensified.

Satellite monitoring

A groundbreaking study recently conducted by Prof. Duan Hongtao of the Nanjing Institute of Geography and Limnology introduced a satellite-based method to gauge the risk posed by these toxins. Traditional optical sensors on satellites cannot detect microcystins as they neither scatter nor absorb light.

Prof. Duan Hongtao emphasized that “to effectively monitor microcystins using satellites, it’s crucial to identify an optical water quality parameter that correlates with remote sensing signals.” In this context, they closely correlate with pigments, specifically chlorophyll-a and phycocyanin.

Phycocyanin is especially noteworthy. It is a distinct pigment found in cyanobacteria and reacts to environmental stimuli in a manner akin to microcystins. The presence of this pigment can indirectly indicate the level of toxins in the water.

By leveraging advanced machine learning techniques and the enhanced random forest regression model, researchers successfully estimated microcystin concentrations through space-based monitoring of phycocyanin levels.

Toxic lakes

The study centered on 100 large lakes in the densely populated regions of eastern China. Utilizing Sentinel-3 OLCI satellite data, researchers mapped microcystin risk dynamics from 2016 to 2021. The findings were concerning: 80 of the 100 lakes displayed high toxin levels at least once.

However, there’s a silver lining. The overall frequency of elevated risks hovers around 1% in most aquatic zones. This suggests that while a majority of these lakes remain viable as potential drinking water sources, consistent monitoring is crucial to identify infrequent but perilous toxin bloom events.

Safe water for all

Beyond the immediate health concerns, this study underscores a pivotal role in achieving the United Nations’ Sustainable Development Goal 6.1, which aims for universal access to safe drinking water by 2030. The act of monitoring microcystin levels directly contributes to the provision of safe and affordable drinking water for everyone. The implications of this research extend beyond China.

Given the global reliance on lakes as primary drinking water sources, this satellite-based approach could revolutionize water quality testing, especially in regions with constrained resources. As global temperatures rise and human intervention persists, we can expect challenges like eutrophication and toxic blooms to escalate. However, innovations such as this satellite-based system equip us to better secure the safety of our drinking water. This advancement serves as a testament to the vital role of science and technology in preserving our most indispensable resource: water.

Explore our advanced remote sensing technology, designed to accurately map phycocyanin levels in your water to detect algae toxins.