www.nasa.gov

The Threat of HABsHABs commonly contain the toxin microcystin, posing a threat to human health and wildlife. For humans, microcystin can cause serious liver damage and has been linked to pansteatitis, a condi-tion in which body fat becomes inflamed. Some scientists suggest a link between the presence of microcystin in drinking water and some forms of liver and colorectal cancer. The toxin also can cause mass deaths of fish and harm those who consume them.

Early detection of HABs can minimize threats of toxic drinking water, provide alerts to close recreational areas around the Great Lakes, and decrease the potential for toxic fish to enter the marketplace. Early Detection of HABs: Satellites, Planes, and BoatsCurrent remote sensing technologies used to monitor these events are limited. For example, high-resolution satellite data (i.e., Landsat) provide spatial data but are not capable of providing the spectral resolution needed to differentiate a HAB from a nonharmful algal bloom. Thus, water sampling methods—which are time consuming and expensive—had been prevalent.

The NASA–NOAA collaboration used an innovative hyperspectral imager developed at the NASA Glenn Research Center. Hyperspectral imaging divides the electromagnetic spectrum into a multitude of bands to identify a spectral “signature” for a range of organism types. In particular, hyperspectral imaging was used to detect the pigment “phycocyanin”, an indicator of microcystis, in low concentrations. The red in the hyperspectral image is an indicator that phycocyanin is present, and that the water may be becoming toxic.

The hyperspectral imager mounted in NASA aircraft flew several missions over the Great Lakes, while at the same time the NOAA was collecting in situ water samples for direct comparison. The imager scanned several sites of the central and western basins of Lake Erie between 2007 and 2009, documenting concentrations of the algal pigment phycocyanin.

Hyperspectral Remote Sensing of HABsThe hyperspectral imager detects a broad spectral range of 405 to 867 nm with a spectral resolution of 2 nm. Attitude sensors and a GPS receiver enable physical mapping of the spectral data. It is compact, weighing less than 3 kg with low power consumption, making it ideal for mounting on aircraft for aerial remote sensing.

National Aeronautics andSpace Administration

The National Aeronautics and Space Administration (NASA) Glenn Research Center partnered with the National Oceanic and Atmospheric Administration’s (NOAA’s) Great Lakes Environmental Research Laboratory to address the recurrence of harmful algal bloom (HAB) events in the Great Lakes. Within a 4- to 8-week time period in late summer, HABs—which pose significant threats to humans and wildlife—form, spread, and disappear across the Great Lakes.

Remotely Detecting HABs in the Great Lakes

Northeast Corner of Maumee Bay State Park—August 19, 2014The hyperspectral image on right shows strong indication of microcystis (in red). Microcystis may contain the toxin microcystin, which can be harmful to humans, fish, and wildlife. NASA and NOAA have developed a remote sensing capability to detect the pigment phycocyanin (red), an indicator of microcys-tis, in low concentration as an early indicator of HABs.

NOAA developed a critical algorithm for detection of the microcys-tin toxin. The teams then calibrated the results between the aerial remote sensing and water sample measurements. The close match confirmed the unique hyperspectral signature for HABs, which will allow scientists to identify their formation early and reliably through remote sensing.

A Substantial ImpactThe Great Lakes are the Nation’s most important freshwater resource, with more than 60 million people in the region utilizing it for drinking water, transportation, recreation, food production, and manufacturing. The Great Lakes

• Contain over 80 percent of the U.S. supply of surface freshwater

• Contain 18 percent of the total global supply of freshwater

• Provide more than 500 beaches for recreation

• Supply drinking water to more than 40 million U.S. and Canadian citizens

• Provide 56 billion gallons of water daily for municipal, agricultural, and industrial use

These numbers demonstrate the imperative nature of monitoring the lakes to address toxic conditions and underscore the importance of improved technologies to do so.

Impact on a Global ScaleIn April 2014, NASA Glenn Research Center was appointed to lead the U.S. GEO committee on Global Water Quality Products and Services.

Radi

ance

Wavelength (nm)

The spectral signature at the Toledo water intake on August 28, 2014, has very strong indicators for high concentration microcystis algal bloom. The spectral signature at the Cleveland water intake and that near Avon Lake also show indications of algal content, however, they are much less in comparison to that of Toledo.

Flight track on August 7, 2014.

Toledo water intakeAvon Lake intakeCleveland intake

More Informationwww.nasa.gov/press/2015/april/nasa-joins-forces-to-put-satellite-eyes-on-threat-to-us-freshwater/

ContactPriscilla Diem, NASA Glenn Research Center216–433–2095priscilla.diem@nasa.gov

PS–01560–0415